Clinical Medicine Infectious Diseases

  1. Plague: Black Death
    3 forms: bubonic and septic (acquired by flea bite), and pneumonic (transmitted person-person)
  2. Smallpox
    Eliminated 80% of Native American population.
  3. Spanish Flu Pandemic 1918
    • 500M infected
    • 20-40M died
    • 3 waves
    • Unusual pattern of morbidity/mortality: mortality rate 2% vs 0.1%, young and healthy were dying
  4. Cholera
    • Originated in India and spread via trade routes.
    • Thought to be caused by “Miasma” (bad air)
    • John Snow traced cause and considered father of modern epidemiology.
  5. History of Infectious Diseases
    • Van Leeuwenhoek: discovered microbes
    • Jenner: cowpox virus to make smallpox vaccine
    • Semmelweiss: proposed etiology of puerperal fever
    • Koch and Pasteur: advance germ theory
    • Lister: initiated antiseptic principles
  6. Koch’s Postulates
    • Bacteria is present in all cases of the disease.
    • Bacteria can be isolated and grown in culture.
    • Disease can be reproduced by inoculation with bacteria.
    • The same bacteria will be isolated from the experimental host.
    • Limitations: some cannot grow in vitro, absence of animal model, diseases have multiple etiologies, diseases caused by normal flora, silent or subclinical infection,
  7. Future of ID
    • Aging infrastructure: infections related to contaminated water
    • Influenza: next pandemic
    • Bioterrorism: (Category A agents) Anthrax (Bacillus anthracis), Plague (Yersinia pestis), Tularemia (Francisella tularensis), Botulism (Clostridium botulinum), Smallpox
  8. ID Major Cause of Morbidity and Mortality
    • US: pneumonia, sepsis, meningitis, Hep C
    • World: malaria, infectious diarrhea, HIV/AIDS
    • 25% of outpatient visits to PCP; URIs, STIs, UTIs
    • Infections can result in chronic disease, malignancies; cervical, liver and gastric cancers, PUD, atherosclerosis
  9. Infection and Inflammation
    • Classic signs: rubor (erythema), calor (warmth), tumor (pain & swelling), functio laesa
    • Infection can be peripheral or systemic
  10. Systemic Signs of Infection
    • Fever
    • Chills or Rigors (visible chills, involuntary muscle contractions associated with sepsis and bacteremias)
    • Myalgias
    • Headache
    • Anorexia
    • Hypotension (shock)
  11. Systemic Inflammatory Response Syndrome (SIRS)
    • Inflammation due to infection that overwhelms the host.
    • Diagnosis requires 2 or more of the following: Temp > 38°C (100.4°F) or < 36°C (96.8°F), Heart rate > 90, Respiratory rate > 20, WBC > 12k or > 10% bands
    • Sepsis: SIRS + documented infection
    • Severe Sepsis: Sepsis + organ dysfunction (hypoperfusion)
    • Septic Shock: Sepsis – induced hypotension (SBP < 90)
  12. Inflammation Effects
    • Changes in vascular function & permeability
    • Leukocyte mobilization
    • Release of acute phase reactants
    • Release of biologically active mediators; cytokines, prostaglandins, bradykinins
  13. Fever
    • Core body temp average 37.5°C (98.6°F).
    • Thermoregulatory center in the anterior hypothalamus.
    • Hyperthermia is the uncontrolled increase in body temp due to dysfunction of the thermoregulatory center; heat stroke syndromes, adverse pharmacologic rxns, certain metabolic disorders.
    • Fever varies over course of day; max oral temp 37.2°C (98.9°F) at 6am and max oral temp 37.7°C (99.9°F) at 4pm. White count also fluctuates.
    • Low grade fevers may be significant in infants and elderly.
    • Subnormal temp, especially in elderly and immunocompromised, can indicate severe infection.
  14. Causes of Fever
    • Infection; acute or chronic
    • Connective tissue disease
    • Malignancy
    • Drug rxn
    • Hyperthermia
    • Fever of unknown origin (FUO)
  15. Fever Categories
    • Fever + Localizing Symptoms
    • Fever Only; no localizing symptoms
    • Fever + Rash
    • Fever + Lymphadenopathy
  16. Fever Only
    • Viruses: EBV, CMV, enteroviruses, various respiratory viruses
    • Bacteria: no animal exposure (S. Typhi, Paratyphi, Listeria, S. aureus), animal exposure (Coxiella, Leptospira, Brucella, Ehrlichia), M. tuberculosis, H. capsulatum
  17. Fever + Rash
    • Viruses
    • Maculopapular rash: EBV, CMV, HIV, measles, mumps, rubella, roseola, parvovirus B19
    • Vesicular rash: Coxsackie A, HSV, VZV
    • Bacteria: S. typhi, T. pallidum, GABHS (scarlet fever, TSS), S. aureus (TSS), N. meningitidis, N. gonorrhoeae, Borrelia, rickettsial diseases
  18. Fever + Lymphadenopathy
    • Generalized or Regional lymphadenopathy
    • Viruses (generalized): EBV, CMV, HIV
    • Bacteria (regional): tuberculosis, cat-scratch disease, tularemia, plague
    • Protozoa: toxoplasmosis
  19. Fever in Special Populations
    • Neonates
    • Hospitalized patients; nosocomial, post-operative
    • Immunocompromised; HIV pts, neutropenic pts, pts on immunosuppressive therapy, elderly, pregnant women
    • Travelers
  20. Fever of Unknown Origin (FUO)
    • Documented fever ≥ 38.3°C (101°F) for a minimum of 3 wks with no clear diagnosis after 1 wk of work-up.
    • Categories: classic (most commonly due to infection, malignancies, inflammatory disorders or drugs), nosocomial, neutropenic, HIV associated (usually due to CMV or indwelling lines)
    • Differential diagnosis: neoplastic diseases (leukemia, Hodgkin and non-Hodgkin lymphoma, solid tumors), collagen vascular diseases, drug fevers, granulomatous disease (Sarcoid probably most common).
  21. Infections Likely to Present as FUOs
    • Tuberculosis (especially disseminated disease)
    • Abscesses (abdominal, pelvic, dental, tuboovarian)
    • Endocarditis
    • Sinusitis
    • Osteomyelitis
    • Viral infections (EBV, CMV, HIV)
  22. FUO Work-up
    • Meticulous history and physical exam (repeated)
    • Always offer HIV testing
    • Biopsy any suspicious lesions
    • Consider bone marrow biopsy
    • Rule out factitious disorder
    • Some diseases have along incubation period.
  23. Silent Infections
    • Tuberculosis
    • STDs (chlamydia in females, HPV types 16 and 18, syphilis)
    • Hep B
    • Hep C
    • Helicobacter pylori gastritis
  24. Infectious Disease HPI
    • Onset, duration, characterization of current symptoms
    • Medication use
    • Occupational exposures, hobbies
    • Sick contacts
    • ETOH/drug use
    • Travel
    • Sexual activities
  25. Infectious Disease PE
    • Focused and guided by history and symptoms
    • Examine skin and lymph, especially axilla and groin.
    • Consider systemic febrile syndromes.
    • Consider silent infections.
  26. Infectious Disease Lab
    • Problem focused; ex. UA, rapid strep
    • CBC diff
    • Urine culture
    • Routine chemistries
    • Blood cultures
    • ESR erythrocyte sedimentation rate
    • CSF exam
    • Joint fluid exam (N. gonorrhoeae)
    • Serologic studies (IgM)
    • Radiologic exam (ex CXR)
  27. Guidelines for Empiric Therapy
    • Select therapy to cover microbes most likely to be causing patient’s infections.
    • Order appropriate tests and cultures (based on PMH and PE) before initiating therapy.
    • If causative organism is isolated, specific therapy should replace empiric therapy.
  28. ID Primary Care Screening Tool
    • Prevention; immunization history, risky behavior modification
    • Identification of silent infections; treatment, prevention of complications, prevention of transmission.
    • Risk counseling.
  29. Viral & Bacterial Infections
    • HEENT: conjunctivitis, otitis externa, OM, rhinitis, sinusitis, pharyngitis
    • Lungs: bronchitis, pneumonia
    • Heart: pericarditis, endocarditis
    • Abdomen: appendicitis, peritonitis, intra-abdominal abscesses, gastritis, gastroenteritis/ infectious diarrhea
    • Skin: folliculitis, abscesses, furuncles, carbuncles, cellulitis, erysipelas, herpes labialis, genital herpes, chicken pox (varicella)/ shingles, necrotizing fasciitis, viral exanthems
    • CNS: meningitis, encephalitis, meningoencephalitis
    • Musculoskeletal: septic bursitis, septic arthritis, osteomyelitis
    • GU: cystitis, pyelonephritis, STIs
  30. Eye Infections
    • Conjunctivitis
    • Dacryocystitis
    • Blepharitis
    • Sty (hordeolum)
    • Keratitis
  31. Conjunctivitis
    • Most common eye infection
    • Viral or bacterial, both self-limiting, topical antibiotics often used.
    • Viral Conjunctivitis: usually adenovirus
    • Bacterial Conjunctivitis: S. pneumoniae, Haemophilus spp, Moraxella spp, Pseudomonas; infants add: N. gonorrhoeae, C. trachomatis
  32. Dacryocystitis
    Infection of lacrimal sac 2° to obstruction
  33. Blepharitis
    Infection of eyelid margins
  34. Sty (hordeolum)
    • Staphylococcal abscess of eyelid.
    • Treat with warm compresses, may add antibiotics.
  35. Keratitis
    • Infection of the cornea, can be viral, bacterial, fungal or parasitic (amoebic).
    • Viral Keratitis: usually Herpes simplex
    • Tx: avoidance of steroids is critical
    • Bacterial Keratitis: (very aggressive course), P. aeruginosa, S. pneumoniae, Moraxella spp., staphylococci
    • Tx: ↑ use of topical quinolones
    • Contact lens use and corneal trauma are risk factors.
    • Always ask if patient wears contact lenses!
    • Must return if not better in 48 hrs.
  36. Ear Infections
    • Otitis Externa
    • Otitis Media
  37. Otitis Externa
    • Swimmer’s ear
    • Infection of external auditory canal
    • S/S: severe pain, itching, ± discharge, ↓ hearing (secondary to inflammation of EAC)
    • Risk factors: any activity that leaves water in ear or mild mechanical trauma
    • Etiologies: P. aeruginosa, Proteus, S. aureus
    • Tx: topical antibiotics + hydrocortisone
  38. Acute Otitis Media
    • Infection of the middle ear.
    • More common in children but can occur in adults
    • Usually secondary to viral upper respiratory infection
    • S/S: pain, occasionally purulent otorrhea
    • Etiologies: H. influenza (primary), M. catarrhalis, S. pneumoniae, S. aureus, group A streptococci; occasionally viruses
    • Tx: amoxicillin, macrolides (PCN allergic) (Azithromycin/Zithromax, Clarithromycin/Biaxin), amoxicillin + clavulanic acid (Augmentin), 2nd/3rd generation cephalosporin, IM ceftriaxone (long T½)
  39. Nose/Sinus Infections
    • Rhinitis
    • Acute Rhinosinusitis
  40. Rhinitis
    • Viral: common cold
    • Large number of rhinovirus and coronavirus serotypes assure lifelong susceptibility
    • Sx: headache, nasal congestion, sore throat
    • Tx: symptomatic/supportive, topical decongestants, oral decongestants, mucolytics
    • Antibiotics have no role; won’t prevent 2° bacterial infections
  41. Acute Rhinosinusitis
    • Very common
    • Usually follows viral upper respiratory infections.
    • Most reliable sign is duration of symptoms: Nasocongestion that doesn’t improve after 7 days or nasocongestion + fever.
    • Sx: headache, localized sinus pain/pressure, ± nasal discharge, fever
    • Atypical symptoms in children
    • Etiologies: S. pneumoniae, M. catarrhalis, H. influenzae, S. aureus
    • Tx: amoxicillin, SMZ/TMP, cephalosporins, macrolides, quinolones (Levaquin, Avelox; last resort)
  42. Oropharynx Infections
  43. Pharyngitis
    • Rapid test only or add culture? Culture is gold standard.
    • Clinical Dx: Centor criteria; fever > 38°C, tender anterior cervical nodes (mono has tender posterior cervical nodes), lack of other respiratory symptoms, presence of an exudate
    • Other S/S: smells bad, maculopapular rash (scarlet fever), beefy red appearance, ↑ WBC with ↑ neutrophils (mono has ↑ lymphocytes)
    • Etiologies other than GABHS: Group C streptococci, N. gonorrhoeae, C. trachomatis, Mycoplasma spp., viruses including EBV, C. diphtheria, C. haemolyticum, anaerobic streptococci
    • Tx: penicillin is drug of choice (DOC), single IM injection, cephalosporin (shorter course), erythromycin/azithromycin for PCN allergy, clindamycin for recurrence
  44. Lower Respiratory Infections
    • Bronchitis
    • Bronchiolitis
    • Pneumonia
    • Common: mild to fatal
    • Etiology related to age of patient, RSV, Human metapneumovirus, Influenza A & B
    • CAP vs nosocomial
    • Preceding viral infection can lead to bacterial 2° infection.
    • Viral pneumonias common in young and old.
  45. Pneumonia
    • Classically a bacterial infection but consider other etiologies
    • Etiology: S. pneumoniae, M. pneumoniae, C. pneumoniae, Legionella spp., rare S. aureus
    • S/S: pleuritic chest pain, productive cough, fever, rales on physical exam
    • Dx: CXR (radiologic findings lag behind clinical findings), CBC with ↑ WBC with ↑ neutrophil, Gram stain & culture of sputum
    • Tx: initiate empirically, tailor as indicated, 3rd generation cephalosporin (differ in ability to cover strep pneumo!), azithromycin/clarithromycin, amoxicillin + clavulanic acid, respiratory quinolones
  46. Acute infectious Arthritis (aka septic arthritis)
    • Etiologies: bacteria most common; also viruses and fungi
    • S. aureus most common cause of all three
    • Sexually active adolescents & young adults: N. gonorrhoeae, usually unilateral knee infection
    • IVDU: P. aeruginosa
    • Tx: joint aspiration is critical, penicillinase-resistant penicillin or vancomycin, ceftriaxone for Gram negative rods
  47. Polyarthritis
    • Rarely infectious in etiology.
    • Can be sequelae of infection with bacteria or viruses.
    • GABHS
    • Chlamydia
    • Enteric bacteria
    • Hepatitis B, Hepatitis C
    • Rubella
    • Parvovirus B19
  48. Septic Bursitis
    • Most cases caused by S. aureus
    • Preceded by trauma, skin infection
  49. Osteomyelitis
    • Usually an infection of the long bones
    • Usually result of hematogenous spread from infected site
    • Trauma an important factor
    • Etiologies: S. aureus, P. aeruginosa, P. multocida
    • Ulcers: polymicrobial; anaerobes
    • Dx: x-rays, blood cultures important
  50. Folliculitis
    • Superficial infection of hair follicle
    • Usually bacterial (S. aureus)
    • Can be viral (HSV) or fungal
    • Hot tub: P. aeruginosa
    • S/S: isolated papules, hair-bearing sites
    • Tx: topical or systemic therapy, mupirocin or retapamulin, cephalexin or dicloxacillin; azithromycin for PCN allergy
  51. Localized Superficial Cutaneous Lesions
    • Abscesses
    • Furuncle
    • Carbuncles
    • Etiology: almost exclusively S. aureus; consider MRSA
    • Tx: incise & drain, systemic antibiotics
  52. Impetigo
    • Etiology: GABHS or S. aureus
    • S/S: lesions may or may not be pruritic
    • Tx: topical mupirocin or retapamulin, oral cephalexin, macrolide if PCN allergic
  53. Herpes Labialis
    • Cold sores
    • Most common manifestation of HSV-1 infection
    • Prodrome of dysesthesia (tingling, burning) precedes development of lesions.
    • Lesions: papule → vesicle → erosion → scab
    • Triggers: stress, sun exposure
    • Tx: topical penciclovir, oral valacyclovir, acyclovir
    • Dx: cutaneous HSV, whitlow, gladiatorum
  54. Human Herpesviruses 1 & 2
    • Triggers: stress, fever / infection, antibiotics and sun exposure
    • Other clinical manifestations: vertical transmission, encephalitis / meningitis, Bell’s palsy (suggested possible link), esophagitis, keratitis, folliculitis
  55. Cellulitis
    • Bacterial infection of deeper layers of skin
    • Etiology: almost always GABHS, also Gram – bacteria in immunocompromised patients
    • S/S: poorly defined borders, more common on lower extremities, very painful, warm
    • Risk: anything that causes break in intact skin, abrasions, lacerations, insect bites, fissuring
    • Tx: cephalexin, amoxicillin + clavulanic acid, expanded spectrum quinolones, macrolides
  56. Erysipelas
    • Cellulitis-like infection of skin, superficial only, face, legs
    • Common in children, older adults
    • Clue: raised borders
    • Etiology: GABHS
    • Tx: same as cellulitis, cephalexin, amoxicillin + clavulanic acid, expanded spectrum quinolones, macrolides
  57. Necrotizing Soft Tissue Infections
    • Necrotizing cellulitis
    • Necrotizing fasciitis (hallmark sign is pain out of proportion to physical findings)
    • Myonecrosis
    • Trauma & surgery increase risk but some cases idiopathic
    • NF of perineum = Fournier’s gangrene; high mortality rate
    • Etiology: GABHS ± S. aureus: anaerobes often involved also, often polymicrobial
    • Tx: debridement, multiple antibiotic regimens
  58. Gastrointestinal Infections
    • Intra-abdominal abscesses
    • Solid organ abscesses
    • Extra-visceral abscesses
    • Peritonitis (primary, secondary)
    • Gastritis
    • Appendicitis
    • Diverticulitis
    • Gastroenteritis / infectious diarrhea
  59. Intra-Abdominal Abscesses
    • Liver most commonly involved
    • Usually 2° to infection at other GI site, trauma or prior transplantation
    • Spleen (2° SCD) or pancreas can also be affected
    • Etiology: usually mixed infection, aerobic and anaerobic Gram negative rods, enterococci, usually polymicrobial
    • Tx: drainage critical, regimen of multiple antibiotics
  60. Peritonitis
    • Primary: aka spontaneous, almost exclusively in patients with ascites
    • Etiology: mostly E. coli, other Gram – rods, enterococci
    • Secondary: to anything that causes bowel leakage, trauma, surgery, high mortality rate, can also develop secondary to peritoneal dialysis
    • Etiology: skin flora
  61. Gastroenteritis / Infectious Diarrhea
    • Epidemiology/ pathogenesis: many microbes (except fungi) are capable of causing diarrhea/ gastroenteritis, history/ exposure very important in determining etiology
    • Travelers are at increased risk
    • Viral: most acute diarrhea
    • Bacterial: blood, fever
    • Need stool workup if diarrhea not improving in 3 days.
  62. Dysentery
    • Invasive diarrheal disease
    • Symptoms result from inflammatory response in colon
    • Etiologies: Salmonella, Shigella. Campylobacter, C. difficile, Yersinia, V. parahaemolyticus, EHEC
    • Tx: antibiotic therapy indicated for Shigella (SMZ/TMP or quinolone) and C. difficile (metronidazole), also severe cases of Campylobacter and Salmonella
    • Consider non-infectious causes of inflammatory colitis.
    • Don’t treat Salmonella (creates carrier state).
    • Shigella usually transmitted person-person, fecal oral route.
  63. Non-Invasive Diarrheas
    • Bacterial: primarily organisms colonize but do not invade small bowel
    • Toxin-mediated: enterotoxins → hypersecretion of isotonic fluid → watery diarrhea
    • Etiologies: ETEC, V. cholerae
    • Viral: produce same clinical picture but do so by invading gut epithelial cells
    • Etiologies: rotavirus, noroviruses
  64. Food Intoxication
    • Results from ingestion of pre-formed toxins
    • Etiologies: S. aureus, B. cereus, C. perfringens
    • Sx: symptoms develop quickly after eating, clinically less diarrhea, more vomiting
  65. CNS Infections
    • Meningitis
    • Encephalitis
    • Meningoencephalitis
  66. Meningitis
    Viral, bacterial, fungal or parasitic (protozoan) in etiology
  67. Encephalitis
    • can be rapidly fatal
    • S/S: altered mental status (AMS), unusual behaviors, ↓ level of consciousness, seizures
    • Patients can present acutely or sub-acutely
    • Acute presentation: fever, HA, neck stiffness, lethargy
    • Sub-acute presentation: HA, focal neurological signs over days-months
  68. Bacterial Meningitis
    • Majority of cases have acute presentation
    • TB meningitis is exception
    • Children, adolescents < 15yrs = ¾ of all cases
    • Etiology age dependent.
    • Neonates: Group B strep, E. coli, Listeria
    • 0-5yo, 14-21yo: N. meningitidis; sporadic outbreaks among these groups in closed settings
    • >5 yrs: S. pneumoniae (#1 cause)
    • Listeria accounts for 10-15% of cases
    • ~¼ of patients have abrupt, fulminating presentation
    • Mortality rate high in this group
    • Remainder have slower onset
    • Dx: lumbar puncture essential
    • CSF: 500-10,000 neutrophils/mcL; ↓glucose, protein,
    • Gram stain positive for causative bacteria in 85% of cases
    • Tx: IV penicillin or 3rd generation cephalosporin, ± vancomycin, prophylax contacts of patients with meningococcal meningitis
  69. Aseptic Meningitis
    • Usually implies viral etiology
    • CSF (direct exam and culture) negative
    • Etiology: enteroviruses (95%): Coxsackie virus, ECHO, mumps, HSV, HIV
    • Like bacterial meningitis more common in younger patients, Seasonal; summer and early fall.
    • S/S: severe HA, fever, photophobia, development of focal neurologic signs worrisome for encephalitis or meningoencephalitis
    • Dx: CSF has significantly lower WBCs, early neutrophils, later monocytes, normal glucose; normal to slightly increased protein
    • Tx: (symptomatic) infection is benign, self-limiting, acyclovir, valacyclovir for HSV infections
  70. Sub-Acute / Chronic Meningitis
    • Signs/symptoms develop over weeks-months
    • Bacterial or viral: HIV, M. tuberculosis, T. pallidum, B. burgdorferi (Stage 3 Lyme disease)
    • Fungi and parasites also have role in chronic CNS infections
  71. Encephalitis
    • Almost always viral
    • Seasonal infection: this provides diagnostic clue
    • Arthropod borne
    • West Nile Virus: important emerging cause
    • HSV: most common cause of viral encephalitis, no seasonal incidence, often preceded by upper respiratory prodrome
    • CSF: lymphocytes, normal glucose, ↑ protein
    • Nucleic acid amplification tests available for diagnosis.
  72. Genitourinary Infections
    • Cystitis
    • Pyelonephritis
    • Prostatitis
    • Epididymitis
    • STDs
  73. Cystitis / Pyelonephritis
    • More frequent in women than men
    • Incidence: increases with age, instrumentation (catheters), pregnancy, anatomic abnormalities of GU tract
    • Ascending infections: endogenously acquired
    • Etiology: E. coli accounts for majority of UTIs (80%)
    • S/S Cystitis: frequency, urgency & dysuria; no back pain
    • Older patients: no or unusual symptoms (AMS), can get urosepsis very quickly
    • S/S Pyelonephritis: fever + CVA tenderness diagnostic
    • Dx: WBCs, bacteria ± RBCs on urinalysis, WBC in pyelonephritis; culture, >105 bacteria = clinically significant
    • Tx: minimum of 3 days for cystitis (7-14 days for pregnant women and children), 7-14 days for pyelonephritis, SMZ/TMP (monitor E. coli resistance), quinolone (Cipro), nitrofurantoin (Macrobid) 7 days, cephalexin (pregnancy)
  74. HEENT
    • Keratitis
    • Acanthamoeba keratitis
    • Otitis Externa
    • Acute Invasive Rhinosinusitis (mucormycosis)
    • Chronic Non-Invasive Rhinosinusitis
    • Allergic Fungal Rhinosinusitis
  75. Lower Respiratory Infections
    • Fungal pneumonias
    • Endemic mycoses
  76. Systemic Mycoses
    • Histoplasmosis
    • Coccidioidomycosis
    • Blastomycosis
  77. Musculoskeletal
    • Fungal arthritis
    • Osteomyelitis
  78. Cutaneous Fungal Infections: Candidiasis
    • Intertrigo
    • Occluded skin
    • Onychia / Paronychia
  79. Risk Factors for Fungal Infection
    • General
    • immunosuppression of any sort/ from any cause: solid organ, bone marrow and stem cell transplantation, extremes of age, immunosuppressive therapy (steroids, immunomodulating drugs: TNF inhibitors, etc), patients with AIDS, increased number of patients having major surgical procedures
    • Keratitis risks: corneal injury involving plant material, pts with chronic disease of ocular surface, contact lens use
    • Cutaneous Candidiasis Risks: occlusion/maceration
    • Superficial Mucosal Candidiasis Risks: mild to moderate immunosuppression
    • Deep Mucosal Candidiasis Risks: severe immunosuppression
    • Dermatophytosis risks: occlusion, atopy, occupational exposure
    • Tinea versicolor risk factors: high humidity, high rate of sebum production, application of “greasy” cosmetics
    • Cryptococcosis Risks: HIV infection, pregnancy, long-term steroid therapy
  80. Keratitis (fungal)
    • risks: corneal injury involving plant material, pts with chronic disease of ocular surface, contact lens use
    • etiologies: Fusarium (↑↑ incidence; US incidence 25-65%), Aspergillus, Candida
    • signs/symptoms: eye pain, foreign body sensation
    • diagnosis: culture of corneal scrapings
    • treatment: antifungal ophthalmic drops, natamycin for Fusarium; polyenes, oral azoles
  81. Acanthamoeba keratitis
    • significant cause of suppurative keratitis in contact lens wearers
    • Infection acquired secondary to improper handling of lenses or swimming, showering or hot tub use while wearing lenses
    • symptoms: similar to fungal keratitis
    • etiology: ~8 species of Acanthamoeba implicated in human disease
    • treatment: difficult secondary to organism’s ability to encyst within cornea, chlorhexidine; polyhexamethyl biguanide, oral & topical azoles
  82. otitis externa
    • Etiology: Aspergillus species most commonly involved (>90% of fungal otitis externa), Candida species second most commonly involved
    • Fungal OE can be acute or chronic; often results from overuse of topical antibiotics, fungal debris often visible in EAC
    • treatment: topical acetic acid preparations; topical azoles, systemic therapy for severe cases
  83. Rhinosinusitis
    • 3 categories of disease
    • Acute invasive: (aka mucormycosis)
    • Etiology: caused by the Zygomycetes (Mucor, Absidia, Rhizopus), rapid, fulminant course in immunocompromised patients
    • Chronic non-invasive: common in immunocompetent patients
    • Etiologic agents: Aspergillus, Penicillium, many dematiaceous fungi: Alternaria, Cladosporium, Bipolaris
    • Allergic fungal: enhanced response to environmental fungi, underlying allergic rhinitis common
  84. Fungal pneumonias
    Etiologic agents: Zygomycetes, hyaline Hyphomycetes, dematiaceous Hyphomycetes, endemic mycoses (only pneumonias likely to occur in immunocompetent patients; exception: allergic, non-invasive pulmonary aspergillosis), yeasts (including Pneumocystis pneumonia),
  85. Endemic mycoses
    • Dimorphic fungi
    • Most likely to present as CAP (community- acquired pneumonia) are Histoplasma, Blastomyces and Coccidioides
    • Transmission: infections are acquired by inhalation; most go unrecognized as only small fraction of patients become symptomatic
    • Natural course is spontaneous resolution unless: inoculum is very large, host is immunocompromised
  86. Systemic Mycoses
    • endemic mycoses causing systemic problems
    • Histoplasmosis
    • Coccidiomycosis
    • Blastomycosis
  87. Histoplasmosis
    • Etiology: Histoplasma capsulatum
    • Endemic in Ohio/Mississippi River Valleys and associated with bird droppings (bat, chicken, starling)
    • Clinical Presentation: ~5% of primary infections present as acute pneumonias, disseminated disease occurs mostly in immunocompromised patients, patients with chronic pulmonary disease may have persistent disease confined to lungs
    • Tx: po itraconazole or IV amphotericin
  88. Coccidioidomycosis
    • Etiology: Coccidioides immitis/posadasii
    • geographically limited to North, South & Central Americas (US: California, Texas and Arizona)
    • S/S: primary infection when it develops, = fever, cough, pleuritic pain ± arthralgias
    • Disseminated disease: rare and can involve any organ. pregnancy increases risk of disseminated disease. African-Americans, Filipinos also at increased risk
  89. Blastomycosis
    • Etiology: Blastomyces dermatitidis
    • organism is related to Histoplasma
    • geographically limited to North America and parts of Africa. Endemic in Ohio/Mississippi River Valleys. Epidemics in NC, MN, IL, WS and VA common
    • Clinical Presentation: primary pulmonary disease" resolution, chronic lung disease OR disseminated disease
    • Disseminated disease: predilection for bones, skin, GU system
    • Tx: itraconazole for 3 months
  90. Musculoskeletal
    • Fungal arthritis & osteomyelitis quite rare
    • Likelihood increased with immunosuppression
    • Etiologic agents in immunocompetent patients: Candida species; often acquired secondary to trauma or surgery. Complication of steroid joint injections, endemic mycoses
    • Dematiaceous fungi: post-traumatic
    • Etiologic agents in immunocompromised patients: Candida species, Aspergillus species
  91. Epidemiology of fungal & parasitic CNS infections.
    • Less common than viral & bacterial CNS infections
    • Fungi: meningitis
    • Parasites: focal abscesses
  92. Fungi: Cryptococcosis
    • Immunocompetent hosts
    • Etiologic agent: Cryptococcus neoformans, From pigeon droppings
    • Risks: HIV infection, pregnancy, long-term steroid therapy
    • 1° infection is pulmonary and usually asymptomatic; disseminated disease may involve any organ but high predilection for CNS
    • Sx: severe headache, AMS; meningeal signs less prominent, skin lesions resemble bacterial cellulitis
    • Dx: LP, CSF culture; capsular antigen detection
    • CSF: increased protein; decreased glucose
    • Tx: fluconazole po x 3 months; for more severe cases IV amphotericin B ± 5-flucytosine
    • endemic mycoses, esp Histoplasma and Coccidioides
  93. Parasites
    • Immunocompetent hosts
    • Etiology: cysticercosis (Taenia solium)
    • Amebic meningoencephalitis
    • Etiologic agents: Naegleria species, Acanthamoeba species, Balamuthia mandrillaris
    • Obtained from contaminated water
    • Naegleria: organism invades CNS via cribriform plate; rapidly fatal infection in children and young adults
    • Tx: amphotericin B ± rifampin
    • Acanthamoeba: acquired via contaminated water; clinical disease = granulomatous encephalitis
    • B. mandrillaris: Subacute meningoencephalitis
    • Immunosuppression increases spectrum
  94. General Superficial and Cutaneous Infections
    • Tinea versicolor
    • Dermatophytic infections
    • Muco-cutaneous candidiasis
    • Onychomycosis
  95. Candidiasis Cutaneous disease
    • Occlusion/maceration are risks
    • Intertrigo (skin opposing skin): axillae, groin, intergluteal, inframammary, webspaces of digits
    • Occluded skin: under bandages/casts, on backs of bed-ridden patients
    • Onychia/paronychia
    • Paronychia: occupational exposure to water, finger nails and toe nails
    • Fingernails: secondary to frequent hand-washing
    • Toenails: secondary to occlusion
    • Tx: nystatin, topical or oral triazoles
  96. Candidiasis Mucosal disease
    • Superficial: mild to moderate immunosuppression is a risk, oropharynx, vagina and angles of mouth (cheilitis)
    • Deep: severe immunosuppression is risk, esophagus, tracheobronchial tree, bladder
    • AIDS-defining illness
    • Once deep mucosa is invaded Candida can become invasive
    • Tx: nystatin, topical or oral triazoles
    • New agents: echinocandins, caspofungin is prototype
  97. Dermatophytosis
    • Superficial mycosis
    • Infect skin, hair & nails
    • Clinical manifestations referred to as tinea
    • Infections transmitted person-to-person via fomites, animal-to-humans directly or via soil
    • Risks: occlusion, atopy, occupational exposure
    • Epidemiology: 3 genera responsible for disease; Epidermophyton, Trichosporon, Microsporum
    • Dx: clinical or KOH scrape
    • Tx: topical or oral azoles; allylamines
  98. Tinea versicolor
    • Superficial mycosis
    • Etiology: Malassezia furfur, lipophilic yeast
    • Normal skin flora
    • Risk factors: high humidity, high rate of sebum production, application of “greasy” cosmetics
    • Clinical manifestations: hypo- (or hyper) pigmented lesions on face, trunk and upper extremities
    • Dx: clinical or KOH preparation
    • Tx: topical or oral azoles; selenium sulfide
  99. Enterobiasis
    • “Pinworms”
    • Etiology: Enterobiasis vermicularis
    • Most common parasitic intestinal infection
    • Ingested eggs hatch in duodenum; migrate to cecum where they live
    • At night females crawl out to perineum where they lay eggs
    • Transmission: fecal-oral, inhalation
    • Sx: severe rectal itching
    • Dx: tape test; but often clinical
    • Tx: albendazole (Vermox)
  100. Giardiasis
    • Etiologic agent: Giardia lamblia
    • Most common parasitic enteric pathogen
    • Disease has 4 forms: asymptomatic infection (~60%), acute diarrhea , chronic diarrhea, malabsorption
    • Transmission: fecal-oral, person-to-person or ingestion of contaminated food, water
    • Dx: direct exam of stool. Immunoassay
    • Tx: metronidazole, tinidazole, nitazoxanide
  101. Cryptosporidiosis
    • After giardiasis most common parasitic enteric pathogen
    • Etiology: > 10 species of Cryptosporidium implicated in disease
    • Transmission: identical to Giardia, fecal-oral, person-to-person or ingestion of contaminated food, water
    • Both immunocompetent & immunocompromised at risk
    • S/S: range from mild diarrhea to severe enteritis, biliary complications not unusual in severe disease
    • Dx: immunoassays; nucleic acid amplification
    • Tx: usually none, nitazoxanide for more severe cases
    • Isosporiasis (Isospora belli) & cyclosporiasis (Cyclospora cayetanensis) have similar epidemiology
  102. Amebiasis
    • Etiologic agent: Entamoeba histolytica
    • E. dispar, E. moshkovskii non-pathogenic species
    • Infection rare in US; in developing world is second leading cause of deaths due to protozoal disease
    • Suspect in immigrants, travelers back and forth to endemic areas
    • S/S: disease range from asymptomatic carriage(most common) to severe dysentery
    • Extra-intestinal disease: hepatic abscesses
    • Dx: stool exam; antigen detection assays
    • Tx: metronidazole is DOC
  103. Strongyloidiasis
    • Etiologic agent: Strongyloides stercoralis
    • Endemic in southern US; increased incidence in Appalachia and in Puerto Rico
    • Autoinfection plays important role in maintaining infection for years
    • Sx: mild to severe, waxing/waning GI symptoms; persistent eosinophilia
    • Dx: immunoassay; stool exam difficult
    • Tx: ivermectin, thiabendazole, albendazole
  104. Malaria
    • Blood and tissue protozoa
    • Etiology: Plasmodium spp
    • one of the most devastating infectious diseases worldwide (> 3 million deaths/year)
    • 4 species of Plasmodium; each has different geographic distribution & treatment regimens
    • ~1,000 “imported” cases in US each year
    • Organism initially develops in liver then parasitizes RBCs
    • Complex life cycle involving two hosts: female Anopheles mosquito and humans
    • Travelers to endemic areas must be carefully advised
    • Dx: thick and thin blood films
    • Tx: determined by species/ areas of resistance
  105. Invasive fungal infections
    • Etiologic agents: molds are most common cause of invasive disease in stem cell/ solid organ transplant patients
    • especially implicated: non-fumigatus species of Aspergillus, Zygomycetes, non-albicans species of Candida and hyaline septated fungi (hyalohyphomycoses)
    • Important hyalohyphomycoses: Fusarium, Scedosporium, Acremonium, Paecilomyces
  106. Candida
    • Fungemia: may be self-limiting
    • disseminated disease (organism isolated from 2nd site): retina, CNS, myocardium, liver/spleen
    • Endocarditis frequent complication of fungemia
    • Tx: long-term systemic anti-fungals
  107. Pneumocystis jiroveci (carinii) pneumonia
    • Opportunistic infection that causes disease in a wide variety of immunocompromised patients
    • Worldwide distribution
    • Transmission: 1° acquired via inhalation
    • S/S: SOB; interstitial pneumonia follows accompanied by significant hypoxia
    • Dx: CXR— diffuse patchy infiltrates
    • Tx: SMZ/TMP (Bactrim), Pentamidine, atovaquone ± steroids
  108. Toxoplasmosis
    • Etiology: Toxoplasma gondii
    • Organism develops in intestinal cells of cat (but many animals are hosts); cysts mature in excreted feces
    • Transmission: infection results from ingestion of infected oocytes or contaminated meat
    • Most infections are asymptomatic
    • Clinical manifestations of symptomatic disease:
    • Acute disease: flu-like symptoms
    • Congenital infection
    • Reactive disease in immunocompromised patients; brain, eye and lung most common targets
  109. Fungal & Parasitic Infections Drug Info
    • Be very careful with application of steroids on: axilla, face, and groin
    • Don’t use Lamisil for Candida infections; only works on dermatophytes. Topical azoles work on BOTH Candida and dermatophytes
  110. Public Health Prevention Efforts
    • Sanitation: Maintenance of drinking water supply, removal of refuse and sewage.
    • Vector control: insecticides, pesticides
    • Education
    • Responding to public threats from IDs
    • Screening for asymptomatic IDs: tuberculosis
    • Reportable infections: varies by state
    • Vaccinations
  111. Decrease Transmission of ID by respiratory droplets, fomites, insects, and animals
    • Vaccinate animals
    • Stay away!
    • Post bite prophylaxis
    • Insecticides/pesticides
    • Proper clothing
    • Inspection
    • Personal Protective Measures: Hand washing, Cover nose/mouth, Gloves, Eye protection, Gowns, Proper clothing, Insect repellants, safer sexual practices
  112. Immunocompromised Hosts
    • Individuals who have 1 or more defects in body’s normal defense mechanisms-increased risk for infection.
    • The key here is for the provider to think about different organisms than you would in the normal population.
    • Risks: HIV, Congenital immunodeficiency, Corticosteroid therapy, Biological response modifiers, Hematologic malignancy, Chemotherapy, Asplenia , DM, Renal failure, Organ transplant
    • Prevention: Thorough history and physical, Vaccines (Recommended vs. contraindicated; In general, killed vaccines can be given to all patients; live vaccines are contraindicated in patients with severe immunosuppression), Special populations (i.e. asplenia increases risk of encapsulated organisms), Close contacts and health care workers, Reducing exposures (Avoid tap water, raw/undercooked meat/eggs/seafood, fresh flowers, hand-washing, pet care), Prophylactic medications
  113. Decrease Transmission of STIs
    • Safer sexual practices: Barrier methods
    • Decreasing high risk behaviors
    • Screening
    • Treatment of contacts
    • Reportable infections
    • Vaccines (Hep B, HPV)
  114. USPSTF recommendations:
    • Grade A and B recommendations: discuss with eligible patients and offer as priority
    • Grade C recommendations: need not be provided unless individual circumstances warrant
    • Grade D recommendations: negative recommendations (“don’t”); discourage use of services
    • Grade I recommendations: discuss with patients the uncertainty surrounding these; evidence of their use has thus far failed to show a benefit
  115. Behavioral Counseling
    • High-intensity behavioral counseling to prevent sexually transmitted infections (STIs) for all sexually active adolescents and for adults and increased risk for STIs. Grade: B
    • Current evidence is insufficient to assess the balance of benefits and harms of behavioral counseling to prevent STIs in non-sexually-active adolescents and in adults not at increased risk for STIs. Grade: I
  116. HIV Screening
    • High risk adolescents and adults: Grade A (men having sex with men after 1975, Unprotected sex with multiple partners, Past or present IVDU, Those who exchange sex for money, Other STDs, Sex with HIV infected, bisexual or IVDU, Blood transfusion between 1978-1985)
    • Pregnant women: Grade A
    • Others: Grade C (CDC has different recommendation)
  117. Chlamydia
    • Sexually active women < 25/high risk: Grade A
    • Pregnant women ≤ 24 (older if high risk): Grade B
    • Low-risk women ≥ 25: Grade C
    • Asymptomatic Men: Grade I
  118. Gonorrhea
    • Sexually active women with increased risk: Grade B
    • Pregnant women not at increased risk: Grade I
    • Men at increased risk: Grade I
    • Men/women without increased risk: Grade D
  119. Hepatitis B
    • Pregnant women: Grade A
    • General population: Grade D
  120. Hepatitis C
    • General population: Grade D
    • High-risk population: Grade I
  121. Syphilis
    • Increased risk: Grade A (men who have sex with men and engage in high-risk sexual behavior, commercial sex workers, persons who exchange sex for drugs, those in adult correctional facilities)
    • Pregnant: Grade A
    • General population: Grade D
  122. Live (attenuated) Vaccines
    • Weakened wild virus/bacteria
    • Replicate in host → elicit immune response
    • Uncontrolled replication. Because they work by replicating in the body we don’t give them to people in which replication may proceed uncontrolled.
    • 1-2 doses for long term immunity
    • Immunity equal to that caused by disease
    • If cause disease then adverse reaction
    • Theoretical risk of infection of fetus (only happened with small pox) so don’t give to pregnant women.
    • Anything that would destroy the organism (heat, light) or prohibit replication in the body (circulating antibodies-from blood products or IV immunoglobulins) will make the vaccine ineffective.
  123. Inactivated Vaccines
    • Culture grown organism is inactivated
    • Do NOT replicate in the host
    • Can NOT cause disease
    • Require multiple doses (humoral immunity)
    • NOT affected by circulating antibodies
    • Can give to immunosuppressed
    • Little cellular immunity conferred
  124. Immunoglobulin
    • Passive immunity
    • Babies receive passive immunity from their mothers.
    • Short term
  125. Difference b/w vaccines and immunoglobulin
    • Vaccination: leads to active immunity which is long-term or lifetime
    • Immunoglobulin: passive immunity in which antibodies (human or animal) are injected and provide temporary protection
  126. Tetanus-diphtheria (Td)
    • Tetanus is only vaccine preventable disease that is infectious but not contagious
    • 1° series completed by age 6: Other forms DT or DTaP available for kids <7, contain same amount of tetanus toxoid but more diphtheria.
    • Adults without prior immunization: Td x 2 (4 weeks apart), followed by another in 6-12 months
    • Adults with some prior immunization: Need total of 3
    • Booster every 10 years: not generally recommended more frequently, Increased risk of local reactions
    • Acute “dirty” injuries: TIG (Tetanus Immune Globulin)
    • Adverse reactions: local, Arthus-like, ?Guillain-Barré Syndrome (GBS), Arthus-like reactions are exaggerated local reactions that occur from 2-8 hours after injection. GBS rare.
    • If “allergy” and not life-threatening symptoms need allergy testing
  127. Measles (MMR)
    • Adults born prior to 1957: considered immune*
    • Adults born after 1957: one dose
    • Adults born between 1963-1967: need one dose of current vaccine
    • Students entering college, health care workers, traveling outside US: 2 doses, Separated by 4 weeks
    • Do NOT vaccinate: Pregnant, Immunocompromised (except asymptomatic HIV with CD4 count ≥ 200)
  128. Mumps
    • Adults born prior to 1957: immune
    • Adults born after 1957: one dose
    • 2nd dose: post secondary education, work in health care facility, international travelers
    • Use MMR if need to revaccinate for measles
    • ? Lifetime immunity
    • Do not vaccinate: pregnant women (theoretical risk), immunocompromised
  129. Hepatitis A
    • Hep A is most frequently reported type of hepatitis in U.S.
    • 2 shot series: 6-18 months apart
    • Advised for: travelers to endemic areas and other high risk individuals, IV drug users (IVDU), men having sex with men, occupational risk, chronic liver disease, persons who receive clotting factor concentrates, parents of international adoptees
    • Duration of immunity: ? Lifelong
    • Immune globulin to exposed, unprotected patients
    • Combination Hepatitis A and B vaccine is available for persons 18 and older: 3 injection series (0,1,6-12)
  130. Hepatitis B
    • 3 shot series: 0,1,6-12 months
    • Recommendation: Men who have sex with men, IVDU, multiple sex partners (>1 in previous 6 months), diagnosed with other STI, commercial sex workers, HCWs, public safety workers, inmates
    • end-stage renal disease, chronic liver disease
    • others*
    • HBIG (immune globulin) with vaccine for susceptible exposures
    • Smokers, pts > 50, obese, and those with HIV may not develop immunity after 1st series
  131. Rubella (MMR)
    • Adults born prior to 1957: immune, except if woman who is likely to become pregnant
    • Recommended for: all women of child-bearing age w/o evidence of immunity and health care workers (HCW) exposed to patients that might be pregnant
    • CRS (Congenital rubella syndrome)
    • Do NOT vaccinate: immunocompromised (may give if HIV+ and CD4 count ≥ 200).
    • Anaphylactic reaction to neomycin is a contraindication
  132. Pneumococcal pneumonia (PPSV)
    • Recommendation: Adults 65 and over, Residents of long-term care facilities, Adults of any age with chronic disease, asplenia, sickle cell disease, cochlear implant, alcoholism, and immunocompromised
    • Revaccination: Single revaccination 5 or more years after the first, Immunocompromised, asplenia, chronic renal failure, >65, if first vaccination occurred before the age of 65 and at least 5 years earlier
  133. Varicella
    • All individuals > 13 yo without evidence of immunity
    • 2 dose series: 4 weeks apart
    • Live attenuated virus
    • Do NOT give: to pregnant women or immunocompromised (can give to HIV+ with CD4 count ≥ 200)
    • Contraindicated with neomycin allergy (anaphylaxis)
  134. Herpes Zoster Vaccine
    • FDA approved 2006, ≥ 60 years old
    • ± prior episode of zoster
    • not for immunosuppressed
  135. Influenza
    • Annual vaccine: best if precedes exposure by no more than 2-4 months
    • 2 types: Inactivated (TIV), Live (nasal spray-FluMist)*
    • Recommendation: Adults > 50, Pregnant women, Chronic Diseases (cardiopulmonary, metabolic, renal, hemoglobinopathy, immunosuppression), Health care workers, employees of assisted living facilities, Caregivers of children < 5 years
    • Live vaccine for healthy, non-pregnant people < 50
    • Live attenuated virus replicates in mucosa of UR tract, therefore may cause “cold” symptoms but not influenza. However, may transmit virus to susceptible people therefore should not be used in caregivers of severely immunocompromised
    • Severe egg allergy is a contraindication
  136. Pertussis (Tdap)
    • Adacel licensed in June 2005
    • Tetanus, diphtheria, and pertussis protection
    • Approved for ages 11-64 as single dose for those completing Dtap series
    • All adults should receive one Tdap, replacing usual Td, if last Td 10 years previous
    • May give before 10 years if high risk
    • Postpartum, close contact with infants <12 months, HCW with direct patient contact
    • If > 2 yrs since last Td
    • If starting initial series for tetanus, diphtheria, and pertussis, one dose should be Tdap
  137. Human Papilloma Virus
    • Most common STD
    • Gardasil (HPV4): first vaccine to prevent cervical cancer (June 2006)
    • Recommend routine vaccination of girls age 11-12
    • Women aged 13-26 not vaccinated
    • 3 doses, 2nd given 2 months after first, and 3rd given 6 months after first
    • 2009: recommendation for males ages 9-26 years
    • Cervarix (HPV2): approved this year in US
    • Recommended for females ages 10-25 years
  138. Meningococcus (MCV4 or MPSV4)
    • Meningococcal conjugate vaccine: Menactra® (MCV4)
    • Recommended for college freshman living in dorms and persons 11-55 at increased risk
    • Microbiologists working with N. meningitidis, military recruits, travelers to countries where epidemic, asplenia
    • Adverse event: Guillain-Barré Syndrome
    • Meningococcal polysaccharide vaccine (MPSV4)
    • Preferred vaccine for persons ≥ 56 years old
    • Revaccination with MCV4 is recommended after 5 years for adults who remain at increased risk
    • MMR
    • Varicella
  140. Medications: Antibiotic/Antiviral prophylaxis
    • Meningitis-bacterial
    • ciprofloxicin 500mg po x 1 or
    • ceftriaxone 250 mg IM x 1 or
    • rifampin 600 mg po q12hX4 doses
    • Influenza
    • oseltamivir (Tamiflu) 75mg daily
    • zanamivir (Relenza) 2 inhalations daily
    • 10 days if household contact
    • 28 days if community outbreak
    • Vaccine
    • Treatment of asymptomatic illness
    • Latent TB
Card Set
Clinical Medicine Infectious Diseases
Clinical Medicine Infectious Disease