Mycoplasma, Rickettsias, Chlamydias, Spirochetes, Vibrios Nestor T. Hilvano, M.D., M.P.H.

Learning Objectives 1.Discuss the damage done to respiratory epithelial cells by Mycoplasma pneumoniae. 2.Describe the three species of Rickettsia that are responsible for human infections. 3.Describe the rash and petechiae of Rocky Mountain spotted fever. 4.Describe Chlamydia including the two cellular forms. 5.Explain how non-sexually active children may become infected with C. trachomatis. 6.Describe the cause and symptoms of lymphogranuloma venereum. 7.Describe three diseases associated with Chlamydia pneumoniae. 8.Describe the disease caused by Treponema pallidum. 9.Describe Lyme disease, its vector, and its causative agent. 10. Describe the action of cholera toxin in causing cholera. 11. Name two species of Vibrio transmitted via contaminated shellfish and describe their diseases. 12. Describe gastroenteritis caused by Campylobacter jejuni. 13. Discuss the major change in medical opinion of the cause of peptic ulcers. 14. Describe the effect of Helicobacter pylori of the lining of the human stomach.

Mycoplasma Smallest, free-living (0.1 to 0.8 um) lack cell wall Require growth factors Except M. pneumoniae, all are facultative anaerobes, with fried-egg shaped colonies seen on agar M. genitalium and Ureaplasma urealyticum – cause nongonococcal urethritis M. hominis – cause pyelonephritis, postpartum fever, PID

Mycoplasma pneumonia Primary atypical pneumonia (walking pneumonia)- mild case, does not generally require hospitalization; spread via droplets Attaches to receptors in human respiratory tract; interrupt removal of mucus Common between 5 to 15 yrs. old and adults younger than 40 ; last several weeks Difficult to diagnose – grow slowly in culture, 2 to 6 weeks Rx – erythromycin or tetracycline Prev – personal hygiene, avoid contact with fomites, reduced aerosol dispersion No vaccine

Rickettsias Gm (-), non-motile, aerobic, intracellular parasites R. rickettsii – rocky mountain spotted fever, prevalent in Appalachian mountains, Oklahoma, and southeastern U.S Transmitted by arthropod vectors ticks (genus Dermacentor) to rabbits/rodents (human incidental host); 3-12 days incubation period S/Sx – fever and spotted, non-itchy rash on trunk and limbs; develop petechiae; spread to organs Prev = wear close fitting cloths, use tick repellant, avoid infested areas Rx = chloramphenicol, tetracycline

Rickettsias R. typhi – cause murine typhus - fleas are main vectors; endemic in U.S. - symptoms in 10 days, lasts about 3 weeks, not fatal - fever, chills, headache, muscle pain, nausea, rash in less than half of patients R. prowazeki – cause epidemic typhus (louse-borne typhus) - human are primary host; squirrels and their fleas - dev. recurrence many years later (Brill-Zinsser disease) - occurs in crowded, unsanitary living conditions; endemic in central and south america, africa, and eastern U.S. - fever, physical and mental depression, and rash - attenuated vaccine for high risk populations Dx – S/Sx; serologic tests; fluorescent antibody tests Rx – doxycycline, tetracycline, or chloramphenicol

Clamydias Nonmotile, grow and multiply within vesicles of host cells No cell wall 2 forms = elementary bodies (EB), infective form and can survive outside cells; and reticulate bodies (RB), noninfective intracellular form

Clamydia trachomatis Most common STD in U.S., non-gonococcal urethritis (NGU) Obligate intracellular; um; coccoid Pathogenesis – in man, monkey, and rabbit - via sexual contact, fomites - 7 to 10 days incubation period - painless vesicles on genitals, rupture, heal Sequelae: a. lymphogranuloma venereum (LGV) – enlarge/harden lymph node, form buboes (granulomatous nodules), elephantiasis b. blindness (trachoma) – chlamydia opthalmia in children at birth c. PID – in infected women Dx – find organism, fluorescent (monoclonal) antibody test Rx – tetracycline, or erythromycin; sulfonamides in pregnant women

Spirochetes: Treponema pallidum Gram (-), anaerobe Spirochetes – helical; endoflagellate Epidemic in France, 1495 Duplication time = 30 hours; only in man/monkey Unable to grow in culture; sensitive to drying; killed at 41.5˚C in 1 hr. Pathogenesis: - 1˚ stage = chancre (local response), 10 – 21 days after exposure, remain for 3-6 weeks; hardened and painless - 2˚ stage = systemic response; 4 -8 weeks later; rash on skin, mouth, lips, genitalia; 25% cured, 25% remain latent (carriers), 50% go on to 3˚ stage - 3˚ stage = hyperimmune response; gumma (painful, rubbery lesion in bones, nervous tissue, or skin); can result to dementia, blindness, heart failure, paralysis (tabes dorsalis or neurosyphilis)- dorsal column of s.c. Dx – find organisms; specific antibody test Rx - penicillin

Vibrio cholera Gm (-), curved rod, monotrichous O polysaccharide antigen, Oxidase (+) Strain O1 el Tor causes cholera in areas with poor sewage and water Rx Symptoms dev. 2-3 days after infection Pathogenesis: cholera toxin (exotoxin) activates cAMP conversion, phosphorylates ionic pumps in intestine, moves electrolytes from blood into intestinal lumen, prevent Na+ and K+ absorption, results to osmosis, leading to severe diarrhea Rice watery stool (mucus + epithelial cells) Severe dehydration and electrolyte loss South America, 1 million cases with 10,000 deaths Rx – fluid and electrolyte replacement; tetracycline

Other Vibrios V. parahaemolyticus – cholera-like gastroenteritis after ingestion of contaminated shellfish; self limiting - explosive diarrhea, headache, nausea, vomiting and cramps for 72 hrs. V. vulnificus – septicemia following consumption of contaminated shellfish, and wound infection after washing with contaminated seawater - fatal in half of untreated cases

Campylobacter jejuni Gm (-), microaerophilic, curved Optimum temp. 45˚C (105˚F) Most frequent cause of diarrhea in U.S. (2 million cases per yr.) From contaminated milk/feces of cattle (60% cattle are carriers) 0.1% dev. Guillain Barre syndrome - autoimmune disease, demyelination of facial nerve, usually temporary paralysis of face Usually self-limiting (malaise, fever, bloody diarrhea, may last for 7 – 10 days) Prev – proper food handling and cooking

Helicobacter pylori Slightly helical, motile with sheathed flagella Most are asymptomatic; some develop Peptic Ulcer Penetrate mucous lining, susceptible to damage by gastric acids, can  production of acids Urease (+) to neutralize HCL (urea→ ammonia) Grow at pH 1 to 3 Portal of entry – mouth Dx – Urease test; blood test (antibodies for H. pylori exposure); Upper GI X-ray; Endoscopy Rx – combination of 2- 3 antibiotics with acid inhibitors

Borrelia burgdorferi – cause lyme disease; transmitted to human by deer ticks; skin rash (15 cm), migratory polyarthritis, posible neurological/cardiac abnormalities Borrelia recurrentis – cause epidemic relapsing fever (louse-borne fever); transmitted by human body louse Leptospira interrogans – cause leptospirosis through contact with urine of infected animals or contaminated waterways or soil; S/Sx = fever, pain,liver and kidney dysfunction, usually not fatal; occurs worldwide

Homework 1.Define terms – elementary bodies; reticular bodies; lymphogranuloma venereum; trachoma; gumma; and tabes dorsalis. 2.Discuss rocky mountain spotted fever as to agent, manner of transmission, symptoms, and prevention. 3.Describe the 3 clinical stages of syphilis. 4.Identify the causative microorganisms of the following: walking pneumonia, rocky mountain spotted fever, epidemic typhus, most common STD (non-gonococcal urethritis) in U.S., syphilis, rice watery diarrhea, peptic ulcer, lyme disease, leptospirosis, murine typhus, and louse-borne fever. 5.What is the arthropod vector that transmit disease of Rickettsia rickettsia to human as incidental host?