UNUSUAL BACTERIAL

PATHOGENSNot normally isolateable

Usually gram variable

LEGIONELLA 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

PATHOLOGY 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

BARTONELLA 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

BACILLARY ANGIOMATOSIS 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

GARDNERELLA VAGINALIS 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

MOBILUNCUS 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

STREPTOBACILLUS MONILIFORMIS 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

CALYMATOBACTERIUM 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

Causes Whipples disease, stain with Periodic Acid Schiff Stain ( PAS )