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Lactose-Fermenting Enteric Bacteria
- Grow pink colonies on MacConkey's agar
- EMB Agar: grow purple/black colonies
- E coli: Green sheen
- "CEEK(S)" (in ceek shyps)
- Citrobacter
- E Coli
- Enterobacter
- Klebsiella
- Serratia
E Coli produces β-galactosidase (breaks lactose into glucose and galactose)
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PCN and Gram Negative Bugs
-GNRs are resistant to penicillin G but my be susceptible to PCN derivatives such as ampicillin and amoxicillin
-GN outer membrane layer inhibits entry of penicillin G and vancomycin
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Neisseria
- Gram (-) diplococci
- -ferment glucose
- -produce IgA proteases
- "MeninGococci ferment Maltose and Glucose
- Gonococci ferment Glucose"
- Types:
- 1. Neisseria gonorrhea
- 2. Neisseria meningitiditis
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Neisseria gonorrhea
- -no polysaccharide capsule
- -no maltose fermentation
- -no vaccine (rapid Ag variation of pilus prots)
- -sexually transmitted
- Causes:-gonorrhea
- -septic arthritis
- -neonatal conjunctivitis
- -PID
- -Fitz-Hugh-Curtis Syndrome (liver capsule inflammation, complication of PID)
- Treatment:
- -ceftriaxzone
- -tx chlamydia coinfection (azithromycin, doxcycycline)
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Neisseria Meningiditis
- -polysaccharide capsule
- -maltose fermentation
- -vaccine (none for type B)
- -transmission: respiratory and oral secretions
- Causes:
- -meningococcemia
- -meningitis
- -Waterhouse-Friderichsen syndrome (hemorrhage into adrenal glands)
- Treatment:
- -ceftriazone or PCN G
- -prophylax close contacts with rifampin, ciprofloxacin or ceftriaxone
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Haemophilus influenzae
- -small Gram (-) coccobacillary rod
- -produces IgA protease
- -culture on chocolate agar, needs factor V (NAD+) and X (hematin) for growth
- *can also be cultured with S. aureus which produces Factor V
- Type B (HiB):
- -capsule
- -causes most invasive disease
- Nontypeable strains:
- -mucosal infections (otitis media, conjunctivitis, bronchitis)
Transmission: aerosol
- Causes:
- -Epiglottitis (Cherry red in children)
- -Meningitis
- -Otitis Media
- -Pneumonia
Does NOT cause "flu"
- Treatment:
- -meningitis with ceftriaxone
- -prophylax close contacts with rifampin
- Vaccine:
- -type B capsular polysaccharide (polyribosylribitol phosphate) conjugated to diphtheria toxin
- -2-18 months old
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Legionella pneumophila
- Gram (-) rod
- -gram stains poorly --> use silver stain
- Culture:
- -charcoal yeast extract with iron and cysteine
- Diagnosis:
- -antigen in urine
- Transmission:
- -aerosol from environmental water source habitat
- -no person-to-person transmission!
- Causes:
- 1. Legionnaire's disease
- -severe pneumonia
- -fever
- -GI and CNS sx
- 2. Pontiac Fever
- -mild flu-like syndrome
- Treatment:
- -macrolide or quinolone
"French legionnaire with his silver helmet, sitting around a campfire (charcoal) with his iron dagger - he is no sissy (cysteine)"
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Pseudomonas aeruginosa
- Gram (-) rod
- -aerobic "Aeruginosa -- aerobic"
- -non-lactose fermenting
- -oxidase positive
- -produces procyanin (blue-green pigment)
- -grape-like odor
- -endotoxin (fever, shock)
- -exotoxin A (inactivates EF-2)
- Transmission:
- -water source
*associated with wound and burn infections
- Causes: "PSEUDOmonas"Pneumonia (esp in CF)
- Sepsis (black lesions on skin)
- External otitis
- UTI
- Drug use and Diabetic Osteomyelitis
- Treatment:
- -aminoglycoside + extended spectrum penicillin (piperacillin, ticarcillin)
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E coli
- Virulence Factors:
- -fimbriae: cystitis, pyelonephritis
- -K capsule: pneumonia, neonatal meningitis
- -LPS endotoxin: septic shock
- Strains:
- -EIEC (invasive)
- -ETEC
- -EPEC
- -EHEC
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EIEC
Invasive; dysentery
- Mechanism:
- -microbes invade intestinal mucosa and cause necrosis and inflammation
- -no toxins produces
- -clinical manifestations similar to Shigella
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ETEC
Traveler's diarrhea, watery
- Labile toxin
- Stabile toxin
No inflammation or invasion
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EPEC
Diarrhea usually in children (Pediatrics)
No toxin produced
Adheres to apical surface, flattens villi, prevents absorption
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EHEC
- Dysentery (toxin alone causes necrosis and inflammation)
- *does not ferment sorbitol (vs other E. coli)
- O157:H7
- -most common serotype
- -produces shiga-like toxin
- -HUS (anemia, thrombocytopenia, acute renal failure)
Endothelium swells and narrows lumen leading to mechanical hemolysis and reduced renal blood flow. Damaged endothelium consumes platelets
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Klebsiella
-intestinal flora
-causes lobar pneumonia in alcoholics and diabetics when aspirated
-very mucoid colonies (caused by abundant polysaccharide capsule)
-red "current jelly" sputum
-also causes nosocomial UTIs
- "4 A's"
- Aspiration pneumonia
- Abscesses in lungs and liver
- Alcoholics
- diAbetics
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Salmonella
- -have flagella ("salmon swim")
- -hematogenous dissemination
- -many animal reservoirs
- -produce H2S
- -invades intestinal mucosa and causes a monocytic response
- -can cause bloody diarrhea
- -non-lactose fermenter
-Tx with Abx may prolong sx
- Salmonella typhi
- -causes typhoid fever
- -found only in humans
- -rose spots on the abdomen, fever, HA, diarrhea
- -can remain in gallbladder and cause carrier state
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Shigella
- -no flagella
- -transmission: cell to cell, NO hematogenous spread
- -only reserviors are humans and primates
- -doesn't produce H2S
- -invades intestinal mucosa and causes PMN infiltration
- -often causes bloody diarrhea
- -non-lactose fermenter
Tx with Abx prolong excretion of organism in feces
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Campylobacter jejuni
- -comma or S-shaped
- -oxidase positive
- -grows at 42C (Campylobacter likes the hot campfire)
- Causes:
- -major cause of bloody diarrhea (esp in children)
- Transmission:
- -F/O through foods (poultry, meat, unpasteurized milk)
**common antecedent to Guillain Barre and reactive arthritis
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Vibrio cholerae
- -Comma shaped
- -oxidase positive
- -grows in alkaline media
-endemic to developing countries
- Causes:
- -diffuse rice water diarrhea
-cholera toxin that permanently activates G s (increased cAMP)
- Treatment:
- -prompt oral rehydration
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Yersinia enterocolitica
- Transmission:
- -pet feces
- -contaminated milk
- -pork
- Causes:
- -mesenteric adenitis that can mimic Crohn's or appendicitis
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Helicobacter pylori
rod - -curved
- -urease positive (urease breath test)
- -creates alkaline environment
- Causes:
- -gastritis
- -up to 90% of duodenal ulcers
Risk factor for peptic ulcer, gastric adenomcarcinoma and lymphoma
- Treatment:
- -triple therapy
- -PPI
- -Clarithromycin
- -amoxicillin or metronidazole
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Spirochetes
-spiral shaped bacteria with axial filaments
- "BLT" B is Big
- Borrellia
- Leptospira
- Treponema
Only borrelia can be visualized using aniline dyes in light microscopy
Treponema visualized by dark-field microscopy
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Leptospira interrogans
-found in water contaminated with animal urine
- Causes Leptospirosis:
- -flu-like sx
- -jaundice
- -photophobia with conjunctivitis
*surfers and in tropics (Hawaii)
- Weil's Disease:
- -icterohemorrhagic leptospirosis
- -severe form with jaundice and azotemia (high levels of nitrogen compounds) from liver and kidney dysfunction
- -fever
- -hemorrhage
- -anemia
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Lyme Disease
- -caused by Borrelia burgdorferi
- -common in NE US
- Transmission:
- -tick Ixodes (also a vector for babesia)
- -natural reservoir is mouse (important in tick life cycle)
- Stage 1:
- -erythema chronicum migrans (target lesion)
- -flu-like sx
- Stage 2:
- -neurologic (facial nerve palsy)
- -cardiac (AV node block)
- Stage 3:
- -musculoskeletal (chronic monoarthritis and migratory polyarthritis)
- -neurologic (encephalopathy and polyneuropathy)
- -cutaneous
- "FAKE an Key Lyme pie"
- Facial nerve palsy (typically bilateral)
- Arthritis
- Kardiac block
- Erythema migrans
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Syphilis
Caused by Treponema pallidum
- Primary Syphilis:
- -localized disease
- -painless chancre
- -screen with VDRL and confirm diagnosis with FTA-ABS
- Secondary Syphilis:
- -disseminated disease
- -constitutional sx
- -maculopapular rash (palms and soles)
- -condylomata lata
- -Screen with VDRL, confirm diagnosis with FTA-ABS
- -"Secondary syphilis = systemic"
- Tertiary Syphilis:
- -gummas (chronic granulomas)
- -aortitis (vasa vasorum destruction)
- -neurosyphilis (tabes dorsalis)
- -argyll roberston pupil
- -test spinal fluid with VDRL
- Signs of Tertiary Syphilis:
- -broad-based ataxia
- -positive Romberg
- -Charcot joint
- -stroke w/o HTN
- Congenital Syphilis:
- -Saber shins
- -saddle nose
- -CNVIII deafness
- -Hutchinson's teeth (smaller, more widely spaced)
- -mulberry molars
- *early prevention! placental transmission usually occurs after first trimester
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Argyll Robertson Pupil
- -constricts with accommodation but is not reactive to light
- -associated with tertiary syphilis
"prostitute's pupil": accommodates but does not react
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VDRL false positives
-detects nonspecific antibody that reacts to beef cardiolipin
-used to dx syphilis
- Many false positives:
- -viral infection (mono, hepatitis)
- -some drugs
- -rheumatic fever
- -SLE
- -leprosy
- "VDRL"
- Viruses
- Drugs
- Rheumatic Fever
- Lupus and Leprosy
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Jarisch-Herxheimer reaction
- -Flu-like syndrome immediately after antibiotics are started
- -due to killed bacteria releasing pyrogens
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Zoonotic Bacteria
-infectious diseases transmitted between animals and humans
- Bartonella
- Borrelia burgdorferi
- Borrelia recurrentis
- Brucella
- Campylobacter
- Chlamydia psittaci
- Coxiella burnetii
- Ehrlichia chaffeensis
- Francisella tularensis
- Mycobacterium leprae
- Pasteurella multocida
- Ricekttsia prowazekii
- Rickettsia rickettsii
- Rickettsia typhi
- Yersinia pestis
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Bartonella
- -zoonosis
- -Cat scratch disease
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Borrelia burgdorferi
-zoonosis
Causes: lyme disease
Transmission: Ixodes tick (live on deer and mice)
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Borrelia recurrentis
-zoonosis
Causes: recurrent fever
Transmission: louse (recurrent b/c of variable surface antigens)
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Brucella
-zoonosis
Causes: Brucellosis/undulant fever
Transmission: unpasteurized dairy
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Campylobacter
-zoonosis
Causes: bloody diarrhea
Transmission: puppies, livestock (F/O, ingestion of undercooked meat)
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Chlamydophila psittaci
-zoonosis
Causes: Psittacosis (Parrot disease)
Transmission: Parrots, other birds
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Coxiella burnetii
-zoonosis
- Q fever
- -no arthropod vector
- -presents as pneumonia
- "Q fever is Queer because it has no rash or vector and its causative organism can survive outside in its endospore form"
Transmission: aerosols of cattle/sheep amniotic fever
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Ehrlichia chaffeensis
-zoonosis
- Ehrliciosis
- -monocytes with morula (berry-like inclusions)
Transmission: Lone star tick
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Francisella tularensis
-zoonosis
Causes: Tularemia
Transmission: Rabbits, ticks, deer fly
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Leptospira
-zoonosis
Causes: Leptospirosis
Transmission: animal urine
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Mycobacterium leprae
-zoonosis
Causes: leprosy
Transmission: armadillos, humans
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Pasteurella multocida
-zoonosis
Causes: cellulitis, osteomyelitis
Transmission: animal bite, cats, dogs
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Ricekttsia prowazekii
-zoonosis
- Epidemic typhus
- -rash starts centrally and spreads out, sparing palms and soles
"Rickettsii on the wRists, Typhus on the Trunk"
Transmission: louse
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Rickettsia rickettsii
- -zoonosis
- -broadly distributed in US
- -obligate intracellular organism (need CoA and NAD+)
Rocky Mountain Spotty Fever- -rash typically starts at wrists and ankles then spreads to trunk, palms and soles
- -Classic triad (HA, fever, rash (vasculitis))
"Rickettsii on the wRists, Typhus on the Trunk"
Transmission: Dermacentor tick bite
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Rickettsia typhi
-zoonosis
Causes: endemic typhus
Transmission: fleas
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Yersinia pestis
-zoonosis
Causes: Plague
Transmission: flea (rats and prairie dogs are reservoirs)
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Gardnerella vaginalis
- Gram variable rod
- -pleomorphic
- Causes:
- -vaginosis
- -gray vaginal discharge, fishy smell
- -non-painful
Associated with sexual activity (not an STD)
- Bacterial Vaginosis:
- -overgrowth of certain bacteria in vagina
- -clue cells (vaginal epithelial cells covered in bacteria)
Treatment: metronidazole
"I don't have a clue why I smell fish in the vagina garden"
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Rickettsial diseases with rash
- Rocky Mountain Spotted Fever
- Typhus (endemic, epidemic)
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Rickettsial diseases without rash
- Ehrlichiosis
- Anaplasmosis
- Q fever
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Palm and Sole Rash
"you drive CARS using your palms and soles"
- Coxsackievirus A (hand, foot and mouth disease)
- Rocky Mountain Spotted Fever
- Secondary Syphilis
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Chlamydiae
- Intracellular: can't make ATP
- Chlamys = cloak (intracellular)
-cell wall lacks muramic acid
Cause mucosal infections
- Two forms:
- 1. Elementary body
- -small, dense
- -"is Enfectious and Enters cell via Endocytosis"'
- 2. Reticulate body
- -Replicates in cell by fission
- -form seen on tissue culture
- Chlamydia trachomatis:
- -reactive arthritis
- -conjunctivitis
- -nongonococcal urethritis
- -PID
- C. pneumoniae and C. psittaci:
- -atypical pneumonia
- -transmitted by aerosol
- Diagnosis:
- -cytplasmic inclusions on Giemsa or fluorescent antibody-stained smear
- Treatment:
- -azithromycin (one time tx)
- -OR doxycyclin
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Chlamydia trachomatis serotypes
- A,B and C:
- -chronic infection
- -cause blindness due to follicular conjuntivitis in Africa
- -"ABC = Africa/Blindness/Chronic infection"
- D-K:
- -urethritis/PID
- -ectopic pregnancy
- -neonatal pneumonia (staccato cough)
- -neonatal conjunctivitis
- L1, L2 and L3:
- -lymphogranuloma venereum
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Mycoplasma pneumoniae
- -no cell wall (not seen on Gram stain)
- -membrane contains sterols for stability
- -grown on Eaton's agar
- Causes:
- -atypical "walking" pneumonia (pts <30, military recruits, prisons)
- -insidious onset
- -HA
- -nonproductive cough
- -diffuse interstitial infiltrate
- *Xray looks worse than patient
- High titer of cold agglutinins (IgM)
- -can agglutinate or lyse RBCs
- Treatment:
- -macrolide
- -OR fluoroquinolone
*PCN ineffective since mycoplasma lack cell wall
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