Module 8b unusual bacterial pathogens
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Legionella pneumophila is a fastidious, aerobic bacterium that stains poorly and requires special staining techniques. It can cause pneumonia by growing in warm, moist environments like air conditioning systems and shower heads. It is susceptible to erythromycin and other drugs. Several other Bartonella species can cause diseases in humans transmitted via insect bites like trench fever. Bacterial vaginosis is associated with Gardnerella vaginalis, which is detected in wet smears as it covers vaginal cells. It has a fishy odor and high pH. Metronidazole is used to treat it.
Module 8b unusual bacterial pathogens
- 1. Not normally isolateable Usually gram variable
- 2. L. pneumophila is the prototype bacterium of this group Fastidious, aerobic and stains poorly with gram stain Basic fuchsin must be used as a counterstain Can be grown in buffered charcoal-yeast extract (BCYE), pH 6.9, 35 degrees & 90% humidity Catalase positive & oxidase positive
- 3. Ubiquitous in warm and moist environment Can multiply in free living amoebas and coexist with them in biofilms Contamination from inhalation from airconditioning systems, shower heads Causes pneumonia and lesions within phagocytic cells Susceptible to erythromycin and other drugs such as Rifampin
- 4. B. bacilliformis – causes Oroya fever B. quintana – causes trench fever B. henselae – Cat scratch fever Pleaomorphic and slow growing, difficult to isolate in the laboratory Can be seen in infected tissues stained with Warthin-Starry silver impregnation stain
- 5. Caused by Bartonella, is a disease predominantly of immunosuppressed individuals, particularly AIDS patients Present as an enlarging red ( cranberry like ) papule, often with surrounding scale and erythma Clinical appearance similar with Kaposi’s sarcoma, form of the disease is called peliosis hepatis
- 6. Serologically distinct organism isolated in the female genitourinary tract and associated with vaginosis ( no inflammatory cells ) In wet smears, the bacterial vaginosis yields clue cells ( vaginal epithelial cells covered with many gram variable bacilli Vaginal discharge often have a strange fishy odor with pH over 4.5 Drug of choice is oral metronidazole
- 7. Motile, curved, gram variable, anaerobic rods isolated from “bacterial vaginosis” Possibly part of the vaginal normal anaerobic flora The organisms are most commonly detected but grow with difficulty in aerobic cultures
- 8. Aerobic, highly pleomorphic organism that forms irregular chains of bacilli interspersed with fusiform enlargements and large round bodies Mesophilic, in media with serum, protein, egg yolk, starch & ceases to grow at 22 C Normal inhabitants of rat throats, and humans can be infected with rat bites characterized by septic fever, petechial rashes, and a very painful polyarthritis
- 9. C. granulomatis, related to Klebsiella and causes granuloma inguinale, an uncommon STD characterized by genital ulcers. Hard to culture even with media enriched with egg yolk Effective treatment with ampicillin and tetracycline CausesWhipples disease, stain with Periodic Acid Schiff Stain ( PAS )