Micro 120

• Mucus to trap microbes
• Ciliary movement to move mucus to noseand mouth for elimination
• Streptococci, lactobacilli and Moraxellacatarrhalis in upper respiratory tract
• Lower respiratory tract and sinuses aresterile
• Alveolar macrophages
• IgA in secretions

• Upper respiratory infection
• Symptoms:– Sneezing– Nasal congestion– Excess nasal mucus (rhinorrhea)– Sometimes: sore throat, fever, headache• Cause: Rhinovirus, coronavirus– Picornavirus– ~100 different Rhinovirus serotypes– Coronavirus: glycoprotein spikes on surface• Transmission:– hand-to-hand-to-nose– fomites
• Occurrence:– October-April in northern hemisphere: coldtemperatures– Infect all populations (only humans)• Host defense:– IgA antibodies in nasal mucosa– Interferon• Prevention & Treatment:– Hand washing– Decontaminate fomites– Interferon

• Transmission– Aerosolized droplets from mouth and nose
• Occurrence:– epidemics and pandemics– Bird and swine reservoirs– Human virus and bird virus mix in swine
• Host defense:– Antibodies against HA & NA– Antigenic drift and antigenic drift: reinfection• Diagnosis– In the clinic by symptoms– For epidemiological monitoring: Culturing virus or identifying viralantigens•
Prevention & Treatment– Annual vaccination (cultured in egg: egg
allergens)– Antivirals administered early in infection or before
infection– New vaccine in development:• cultured in monkey cells• Protective against multiple strains
• Lower respiratory tract infection• Symptoms:– Fever– Headache– Muscle ache– Cough• Cause– Influenza virus– Strains A, B, & C, RNA virus

• H1N1 and H3N2 caused infections• H3N2 and Strain B did not match vaccinestrain

Vaccine includes H1N1, H3N2 and strain B

• Lower respiratory tract infection• Symptoms:– Wheezing in infants– Mild form in children & adults
• Cause– Respiratory syncytial virus (RSV)– Causes formation of large cells with multiple nuclei inrespiratory tissue• Transmission– Hand contact– Respiratory droplets• Occurrence:–
Late winter and early spring– All ages– In the US, RSV causes about
90,000 hospitalizationsand 4,500 deaths per year in children under 5 yr.• Host defense– No lasting immunity• Prevention & Treatment– Hand washing– Supportive care and oxygen to aid breathing

• Upper respiratory tract infection
• Symptoms– Swollen throat– Toxin damages cells, cells produce apseudomembrane of dead cells– Sudden death by suffocation
• Cause– Corynebacterium diphtheriae– Gram positive, rod– Diphtheria toxin
• Gene carried on a bacteriophage
• AB toxin
• A subunit enters host cell and disrupts protein synthesis

• Transmission– Humans are only host– Respiratory droplets from carriers and patients
• Occurrence– Among unvaccinated children
• Host defense– Antibodies that bind toxin
• Prevention & Treatment– Vaccine; requires a booster every 10 years– Antitoxin soon after infection

• Upper respiratory tract infection• Symptoms– Sore throat, fever, chills, headache– Inflamed pharynx, White exudate on tonsils– Swollen lymph nodes in neck
• Cause– Streptococcus pyogenes– Gram positive cocci found in chains– Group A, beta-hemolytic on blood agar
• Transmission– Person to person by respiratory droplets– Contaminated food– Unpasteurized milk

• Occurrence– School age children humans are the only host
• Diagnosis– Culturing organism in the lab followed by diagnostic tests– Rapid latex agglutination kits
• Prevention & Treatment– Antibiotics

• Complications– Scarlet fever:
• Caused by strains that secrete an erythrogenictoxin that kills cells
• Toxin on prophage
• Causes Intense inflammation
• Rash and fever– Rheumatic fever
• Inflammation in multiple organs: joints, skin, brain
• Damage to heart valves
• Leading cause of heart disease in children
• Prevented by using antibiotics
• Recurrence can be fatal, maintenance antibiotics

– Acute poststreptococcal glomerulonephritis
• Sudden kidney failure
• Urine becomes scant & dark
• Body swells from retained fluids

• Cause– Streptococcus pneumoniae– Gram positive cocci, occur in pairs– Have a thick capsule
• Transmission– Respiratory droplets
• Lower respiratory tract infection• Symptoms– High fever– Chest pain– Fluid in alveoli• Occurrence– All ages, especially elderly and children– Recovery confers immunity• Host defense– Inflammatory response which caused symptoms– Phagocytes ineffective because of capsule– Antibodies• Prevention & Treatment– Antibiotics– Vaccination

• Lower respiratory tract infection• Symptoms– Slow onset headache– Mild symptoms fever– Atypical/ walking pneumoniacough• Cause– Mycoplasma pneumoniae– Grows in trachea
• Transmission– Respiratory droplets
• Occurrence– Alls ages especially school age children, teenagers
• Host defense
• Prevention & Treatment– Tetracyclines and erythromycins

• Lower respiratory tract infection– July 1976, 182 people took ill and 26 died during a American Legionconvention in Philadelphia
• Symptoms– Weakness Chills– Headache Cough– High fever

• Cause– Legionella pneumophila– Small, aerobic, rod– Fastidious, grown in fertilized eggs and guinea pigs
• Transmission– Grows in standing water– Survives heat & chlorination: becomes aerosolized– Grows in cooling towers
• Occurrence– Any age– Elderly and smokers are more susceptible• Diagnosis– ELISA, RIA– Antibody staining of clinical specimens– Culturing in the lab• Prevention & Treatment– Antibiotics: erythromycin because of resistance to
others

• Lower respiratory tract infection
• Symptoms– Sore throat– Tiredness– Cough progressing to choking cough & suffocation
• Cause– Bordetella pertussis– Small Gram negative coccobacillus– Exotoxin: pertussis toxin causes symptoms– Cytotoxin: kills cells of trachea

• Transmission– Respiratory droplets– Humans are sole hosts
• Occurrence– Infants and young children– Unimmunized people– Older adults– Highly contagious and fatal
• Diagnosis– PCR of bacterial DNA– Antibody titers in ELISA
• Prevention & Treatment– Vaccination (DPT, DTaP), booster required– Supportive & erythromycin

• Lower respiratory tract infection– Leading cause of infectious disease death worldwide
• Symptoms-none
• Cause– Mycobacterium tuberculosis– Rod shaped, obligate aerobe– Waxy coat:
• Slow growth (20 hr generation time)
• Does not stain well (Acid fast stain)

• Occurrence– Anyone exposed to the bacterium
• Host defense– Cellular immunity (T cells producelymphokines)
• Prevention & Treatment– Bacille Calmette-Guerin (BCG) vaccine– Tuberculin skin test to monitor infections(delayed hypersensitivity reaction)– Isoniazid or multidrug– Emergence of multidrug resistant TB

• Lower respiratory tract infection
• Symptoms– Flu-like illness: fever, chills, cough, shortness of breath– Immunocompromised people develop chronicrespiratory illness or disseminated infection
– Occurs in three forms:
• Acute Histoplasmosis• Chronic Histoplasmosis
• Disseminated Histoplasmosis

• Cause– Histoplasma capsulatum– Grows as single cells (yeast) and mycelia in soil– Found in soil rich in bat & bird droppings
• Transmission– Inhalation of spores

• Occurrence– People exposed tocontaminated soil– Exploring caves, barns etc where bats & birds dwell
• Prevention & Treatment– Amphotericin B orKetoconazole for people withnormal immune system

• Lower respiratory tract infection
• Symptoms– Fluid accumulation– Tissue scaring– Respiration compromised– Low blood oxygen
• Cause– Pneumocystis carinii– Opportunistic pathogen

• Transmission– Found in the lungs of most peoplefrom an early age
*Occurrence– Disease in immunocompromised people
• Host defense– Cytotoxic T cells, Interferon gamma
• Prevention & Treatment– Nothing much, treatments not tolerated byAIDS patients

• Seamless epithelial layer
• Peristalsis movement
• Bacteriocidal chemicals– Lysozyme in saliva– Bile– Hydrochloric acid in stomach
• Secretory IgA
• Esophagus, stomach & upper smallintestine have no resident microbes
• Exchange of genetic material betweenbacteria in intestine

Streptococcus salivarius, Staphylococcusepidermidis, Moraxella catarrhalis, Lactobacillus,Candida albicans

Anaerobes: BacteroidesBifidobacterium,Fusobacterium, ClostridiumFacultative anaerobes: E. coli, Proteus spp.,Klebsiella spp., S. aureus, Lactobacillus spp.,

• Symptoms– Swelling of salivary glands– Fever, headache, tiredness
• Complications– Meningitis– Inflammation of testicles (orchitis)– Inflammation of ovaries and breasts– Spontaneous abortion– Permanent deafness
• Cause– Mumps virus– Helical, enveloped, single stranded RNA virus• Transmission– Respiratory droplets– Fomites– Person is infectious 3 days before to 9 days after symptoms appear

• Occurrence– Unvaccinated population
• Host Defense– Interferon– T & B cell response– Life long immunity
• Diagnosis– Clinical symptoms– Lab detection of viral antigens & antibodies
• Prevention & Treatment– MMR vaccine (live attenuated virus)– No treatment

• Symptoms– Diarrhea - Dehydration– Vomiting– Abdominal discomfort– Fever
• Cause– Rotavirus– Damages the epithelial cells of the intestine

• Transmission– Fecal oral– Very infectious: epidemics– Fomites
• Occurrence– Young children, 2.7 m cases per year in US among <5yr– Day care settings– Winter

• Host Defense– IgA– Breast feeding protects infants
• Diagnosis– Symptoms– ELISA if needed

• Prevention & Treatment– Rehydration and supportive care– Good hygiene– Live attenuated oral vaccine with 5 strains of rotavirus (RotaTeq)Withdrawn– New vaccine approved Feb 2008: live oral (Rotarix)

• Symptoms– Diarrhea - Headache– Vomiting - Abdominal cramps– Tiredness - Low fever
• Cause– Norwalk virus/ norovirus– Non-enveloped, RNA virus
• Transmission– Fecal oral– Contaminated food and water, uncooked food– Aerosolization of vomit

• Occurrence– Older children and adults– Highly infectious– Cruise ships/ schools
• Host Defense– Antibodies are not protective– Repeated infection by same anddifferent strains

• Diagnosis– Symptomatic– RT-PCR, ELISA
• Prevention & Treatment– Supportive– Good hygiene– Safe water and food handling– Virus is resistant to freezing, hightemperature (60°C), chlorine (10 ppm)

• Symptoms– Diarrhea - Nausea & vomiting– Jaundice from liver impairment– Fatigue - Loss of taste and smell– Not a chronic infection
• Cause– Hepatitis A– Small, non-enveloped RNA virus– Picornavirus, enterovirus

• Transmission– Fecal oral– Oral-anal sexual contact– Excreted in feces
• Occurrence– All ages– Children often asymptomatic
• Host Defense– Antibodies to HA– Protective (no reinfection)

• Diagnosis– Symptoms– Anti-HA titer
• Prevention & Treatment– Vaccine– Good hygiene, Proper sanitation– Avoid risky behavior

• Symptoms– Jaundice - abdominal pain– Fatigue - Nausea & vomiting– Liver cirrhosis, liver cancer
• Cause– Hepatitis B virus– DNA virus, hepadnavirus family,– HBsAg, HBcAg, HBeAg found in serum– Dane particles: empty

• Transmission– Blood & bodily fluids - Sharing needles– Sexual– Mother to baby during birth
• Occurrence• Host Defense– T & B cell
• Diagnosis Detecting HBsAg and antibodies to it

• Prevention & Treatment– Hepatitis B vaccine (rHBsAg protein)– Antivirals for chronic infection– Don’t share needles– Engage in safe sex, monogamy

• Symptoms– Asymptomatic at initial infection– Chronic hepatitis years (>20 years) later– Liver cirrhosis and cancer in a small percentage
• Cause– HCV virus– Enveloped RNA virus

• Transmission– Transfusion with contaminated blood– Sharing needles with an infected person– Organ transplants from infected person
• Occurrence– >3.2 million chronic infections in the US (CDC, 2006)
• Host Defense– Ineffective immune response because the virus constantlychanges

• Diagnosis–Serology to detect anti-HCV antibodies• Less sensitive, delay for antibody development– PCR to detect viral RNA
• Prevention & Treatment– Limit exposure to blood– Don’t share needles– Treated with multidrug combination that cures– No vaccine

• Symptoms– Diarrhea and Dysentery– Abdominal pain & cramps– Fever, vomiting
• Cause– Shigella sonnei, S. flexneri, S. boydii– 9-15 bacteria can cause disease– Produce Shiga or shiga-like toxin, all are AB toxins
• Transmission– Fecal oral route– Humans are only host (and primates)– Contaminated food and water

• Occurrence– In places with poor sewage or water treatment– Daycare facilities, families
• Host Defense– Non-specific and specific responses– Antibodies to LPS, proteins, toxins
• Diagnosis– Shigella in fecal sample– Blood and neutrophils in stool– Symptoms
• Prevention & Treatment– Antibiotics– Good hygiene

• Symptoms– High fever– Headache, tiredness– Diarrhea
• CauseSalmonella typhimuriumcauses salmonellosis– Salmonella typhi– Bacteria shed by patients and carriers
• Transmission– Fecal oral– Contaminated food and water

• Occurrence– Imported cases in the US– Relatively common in developing countries
• Host Defense– Humoral antibodies, protective
• Diagnosis– Stool tested for S. typhi
• Prevention & Treatment– Antibiotics– Vaccine for travelers, S. typhi Ty21A– Avoid potentially contaminated food & water

Symptoms– Profuse ‘rice water’ diarrhea– Loss of skin elasticity
• Cause– Vibrio cholerae– Gram negative curved rod– Grows in brackish water– Shell fish contaminated with Vibrio– Cholera toxin (AB toxin)
• Transmission– Fecal-oral– Contaminated water & food

• Occurrence– In endemic areas: children– Everyone during epidemics– 1991 American epidemic
• Host Defense– Antibodies to surface antigens
• Diagnosis– Symptomatic
• Prevention & Treatment– Good hygiene, sewage treatment– Clean water,– Rehydration– Oral vaccine for travelers,

• Diseases– Enterotoxigenic (ETEC)
• Watery diarrhea, similar to cholera
• Caused by toxins
• Occurs in children & travelers
• Antibiotics shorten duration, rehydration– Enteropathogenic (EPEC)
• Diarrhea in infants
• Virulence factor is an adhesin on the outer membrane
• Destroys the microvilli of small intestine– Enteroinvasive (EIEC)
• Dysentery, inflammation, fever
• Bacteria invade the cells of the intestinal wall
• Toxin genes similar to Shigella toxins and found on plasmid

– Enteroaggregative (EAEC)
• Chronic watery diarrhea in infants– Enterohemorrhagic (EHEC) O157:H7
• Bloody diarrhea, Hemolytic uremic syndrome (HUS)
• Caused by Vero toxin (toxin acquired from Shigella)
• Antibiotics early, supportive
• Transmission– Fecal oral– Contaminated food or water
• Diagnosis– Symptomatic
• Prevention & Treatment– Good hygiene - Hand washing– Supportive (rehydration) - Antibiotics for high risk populations

• Symptoms– Chronic gastritis– 15-20% develop ulcers– Gastric carcinoma
• Cause– Discovered by Marshall & Warren, Nobel 2005– Lives only in humans, stomach & duodenum– Virulence factors• Adhesin to attach to stomach epithelium• Enzyme urease: splits Urea into CO2 &ammonia that increases pH
• Transmission– Unknown, presumed fecal-oral, mouth tomouth– Found in feces and mouth

• Occurrence– Present worldwide in most people– H. felis (cats) & H. helmanii (dogs) can infect humans
• Host Defense– Cellular and humoral immune response
• Diagnosis– Labeled urea converted to CO2 by H. pylori breath test– Serological tests
• Prevention & Treatment– Combination therapy:• Antibiotics to kill bacteria• Chemicals to reduce acid• Compounds to protect the stomach lining

• Symptoms– Diarrhea– Abdominal pain– Colitis (inflammation of the colon)– Pseudomembranous colitis
• Cause– Clostridium difficile– Gram positive, endospore former– Exotoxins A (enterotoxin) causes fluid secretion– Exotoxin B (cytopathic) causes inflammation
• Transmission– Contact with feces or feces contaminated fomites

• Occurrence– Following prolonged antibiotic use– In hospitals– Elderly• Host defense– No immunity– Normal flora
• Diagnosis– Symptoms following antibiotic use– Serology for exotoxin
• Treatment and prevention– Stop antibiotics– Rehydration– Antibiotics to target anaerobic bacteria– Restore normal flora in severe cases

• Symptoms– Gingivitis: red swollen bleeding gums– Tissue and bone loss– Loss of teeth
• Cause– Bacterial plaque with Porphyromonas gingivalis• Transmission– Mouth-mouth
• Occurrence– Usually adults– Smokers more susceptible– Diabetes, certain medications, stress (weakimmune system)

• Diagnosis– Clinical presentation
• Prevention & Treatment– Brush and floss teeth– Antibiotics– Pocket reduction, grafts, dental implants

• Symptoms– Appear 2 weeks after infection– Explosive, foul smelling watery diarrhea– Bloated stomach, foul smelling gas– Long term: Abdominal pain, nausea,occasional diarrhea
• Cause– Giardia lamblia– Protozoan
• Transmission– Water contaminated with cysts– Person-person contact– Oral-anal sex

• Occurrence– Campers who ingests contaminated water– Cities if water supply is contaminated
• Host Defense– IgA– Inflammation at site of attachment• Diagnosis– Cysts in stool sample (infected & carriers)– ELISA for G. lamblia antigens
• Prevention & Treatment– Boiling or filtering water– Chlorination does not kill cysts– Hand washing & personal hygiene– Avoid risky sexual behavior– Metronidazole

• Symptoms– Intense itching around the anus– Disturbed sleep– Irritability– Vaginal irritation if worm enters vagina– (Loss of appetite and weight)
• Cause– Enterobius vermicularis– Small white worm, mates in the intestines,females lay eggs near the anus
• Transmission– Fecal oral– Eggs can survive for up to two weeks onclothes

• Occurrence– School age children– Preschoolers and their caregivers• Host Defense– Unknown
• Diagnosis– Scotch tape test in the morning– Worms on skin or bedclothes
• Prevention & Treatment– Changing undergarments everyday– Wash hands– Wash all clothes during and after treatment– Mebendazole; Two doses separated by two weeks

• Symptoms– Itchy migrating skin lesion at site ofinfection– Mild diarrhea or cramps– Anemia, tiredness, weight loss– Severe cases:• Stunted development• Difficulty breathing• Enlarged heart
• Cause– Ancylostoma duodenale– Necator americanus
• Transmission– Larvae in soil borrow into bare skin– Eggs voided in feces

• Occurrence– Humans and other mammals– People who work with soil– Children playing in contaminated soil• Diagnosis– Eggs in feces
• Host defense– IgE
• Prevention & Treatment– Don’t walk barefooted in contaminated soil or work with barehands– Treated with two doses Mebendazole– Iron supplements for anemia

• Bladder and kidneys are normally free ofmicroorganisms
• Vagina is colonized by Lactobacilli (maintain low pH),aerobic Streptococci & Staphylococci, anaerobicBacteroides & Clostridium, fungi Candida albicans
•Urine washes microbes out of the bladder.
• Microbes usually enter the urinary system throughthe urethra.
• Microbes usually enter the reproductive systemthrough the vagina (in females) or urethra (in males).

• Symptoms:– Frequent urination fever & pain near kidneys– Pain while urinating
• Types of infections– Any or all parts of urinary tract are infected– Cystitis: common bladder inflammation
• E. coli--most common
– Urethritis: infection of urethra
– Pyelonephritis: infection of kidneys
• E. coli 75%
• P-fimbriae

• Occurrence– Females more than males– Pregnant women– Catheters– Anatomical abnormalities or obstructions
• Diagnosis– Symptoms– Bacteria in urine– Urine culture
• Treatment/ prevention– Antibiotics– Good hygiene– Drink plenty of fluids

• Cause– Neisseria gonorrhoeae– Infects the urethra
• Epidemiology– 300,000 cases/yr; 60% age 15-24– Males:
• 80% show symptoms
– Females:
• Often asymptomatic• leads to pelvic inflammatorydisease
– infants:• ophthalmia neonatorum

• Transmission– Sexually transmitted disease– From mother to infant at birth
• Symptoms
– Men:• burning sensation when urinating• a white, yellow, or green dischargefrom the penis• Sometimes painful or swollentesticles
– Women:• painful or burning sensation whenurinating• increased vaginal discharge• vaginal bleeding between periods.

• Occurrence– Sexually active people of all ages
• Treatment & Prevention– Antibiotics: patient and all sexual partners– Condoms
• Complications– potential for systemic infection• gonorrheal endocarditis• gonorrheal meningitis• gonorrheal arthritis

• Cause:– Treponema pallidum– Spirochete
• Congenital STD– Transmission from mother to fetus– Latent stage: Neurological damage– Primary/ secondary stage: stillbirth
• Diagnosis– Microscopic examination of exudate forTreponema.– Serological tests for antibodies
• Treatment & prevention– Antibiotics: Benzathine penicillin (effective for 2weeks)

• Primary stage: several weeks– Hard based chancre– Infectious serous exudate– Bacteria enter blood and lymph
• Secondary stage: 6-8 weeks– Disseminated skin rash– loss of hair– malaise, mild fever– Spirochete in lesions
• Latent period
• Tertiary phase: years later– <50% of untreated cases– T-cell immunity--gummus (rubbery mass)

• Cause– Usually follows gonorrhea– Also caused by Chlamydia trachomatis– Any organism that causes urinary or genital infections
• Symptoms– Inflammation of the infected organs– Severe pain in the lower abdomen
• Infection beyond vagina– Uterus– fallopian tubes– ovaries
• Increased risk if untreated– Infertility– ectopic pregnancy

• Cause– Chlamydia trachomatis
• Occurrence– coinfection with N. gonorrhoeae– most prevalent STD– many cases go untreated– Transmitted to infants at birth• Neonatal eye infection– leading cause
• Infertility• ectopic pregnancy

• Caused by
– Herpes simplex virus
– HSV-2: normally genital tract
– HSV-1: normally mouth and face• cold sores, fever blisters– latency• moves from nerve ending to nerve ganglion• reactivates to epithelial tissue
– Neonatal herpes• Fetus or newborn• brain and internal organs• lifelong disabilities– No cure--controlled with acyclovir

• Human Papilloma virus (HPV)– Over 65 types--based on DNA
• Diseases– benign wart– cervical carcinoma
• Replication– proliferation of cells– basal layer of epithelium• no progeny virus in these cells– cells differentiate• virus replicates in later cells--shed from surface
• Prevention– Vaccine

• Disease– Acquired immunodeficiencysyndrome (AIDS)
• Epidemiology– Crossed from animals to man1930– US since 1970s, first case 1980s
• Cause– Human immunodeficiency virus(HIV)– Infects and replicates in CD4 Tcells– Spreads through out the bodyvia blood

• Stages of HIV infection
– Acute:• Fever fatigue rash headache
– Chronic:• CD8 T cells kill virus infected cells, not symptomatic,• CD4 count decreases
– AIDS:• CD4 <200 per cc, viral load increases• opportunistic infections, death