Pseudomonas & Gram - Organisms

Pseudomonas general characteristics

ubiqutous, very resistant = common contaminant, Gram - rod, motile, catalase +, oxidase +, many make pigments, do not ferment, some use sugars oxidatively (closed vs open tube)

Pseudomonas aeruginosa epidemiology

common in soil/water, intestinal resident, very resistant (common HAI), opportunisitc (don’t normally cross healthy barriers)

Pseudomonas aeruginosa virulence

capsule (adhesin, avoids phagocytosis), LPS (endotoxin), pyocanin (pigment, inhibits cilia in respiratory), exotoxin A (inhibits protein synthesis), exotoxin S (inhibits protein synthesis), cytotoxin, extracellular enzymes (elastase, alkaline protease, phospholipase C, rhamnolipid), antibiotic resistance

Pseudomonas aeruginosa clinical disease

pulmonary infection (common in immunocompromised, mucus binds in lungs and makes breeding grounds, broad spectrum antibiotics/respiratory equipment S), HAI (burn infections, UTI), infections in healthy individuals (hot tube dermatitis, UTI, skin rash, external ear infection, corneal ulcers in contacts)

Pseudomonas aeruginosa lab identification

oxidase +, Gram - rod, characteristic grape odor, green pigment (pyocyanin in burns blue under UV), other tests like IMViC to diff from enterobacteria

Pseudomonas aeruginosa treatment

sensitivity testing very important, combinational therapy most effective - aminoglycoside + beta lactam antibiotic

Brucella general characteristics

tiny gram - coccobacillary, strict aerobe, non fermenter

Brucella epidemiology

common veterinary pathogen, contaminated meat/infected animal, enters through damaged skin/mucus, tissues rich in erythritol (breast, utereus, etc)

Brucella virulence

intracellular pathogen (resists phagocytosis/clearance)

Brucella clinical disease

brucellosis (undulant fever): fluctuating fever, flu like symptoms, can last awhile b/c intracellular, not fatal

Brucella lab identification

patient history (work w/ animals), serological test, genetic tests being developed

Brucella treatment & prevention

combo of doxycycline + rifampin 6 weeks, sulfa in pregnant women; test and eliminate infected animals/quarantine infected animals/pasteurization/animal vaccines available

Bordetella general characteristics

very very tiny, coccobacillary, capsule, strict aerobe, non fermenter

Bordetella epidemiology

reservoir is healthy carriers, primary source is children w/ disease, transmission from droplets/aerosol inhalation

Bordetella virulence

enhance pulmonary disease, filamentous hemaggluitin & pertactin (P69, bind ciliated cells), fimbriae (bind mammalian cells), pertussis toxin & adenylate cyclase toxin (suppresses host, increases cAMP), tracheal cytotoxin (kills ciliated respiratory cells), LPS (endotoxin)

Bordetella clinical disease

Pertussis (whooping cough): three stages catarrhal (1-2 weeks, cold like), paroxysmal stage (1-6 weeks, worst stage, persistent violent cough, 40-50 fits a day, can cause exhaustion/vomitting), convalescent stage (symptoms diminish, secondary complications can occur from ciliated damage); caused by B. pertussis, B. parapertussis causes less form

Bordetella lab identification

culture in vivo requires prolonged incubation on charcoal media, PCR tests sensitive/specific, detection of IgG or IgA for conformation

Bordetella treatment & prevention

erythromycin, DTaP vaccine (doesn’t give long term immunity)

Francisella tularensis general characterisitcs

tiny gram - coccobacillary, strict aerobe, non fermenter

Francisella tularensis epidemiology

zoonotic disease (wild rabbits), endemic to north, transmission from animal bite/direct contact through cut, one of most infectious (10-50 cell) why its on biohazard (pulmonary possible)

Francisella tularensis virulence

antiphagocytic capsule, capable of intracellular growth

Francisella tularensis clinical disease

tularemia (rabbit fever): skin lesions then move to more systemic symptoms

Francisella tularensis treatment

gentamicin (intracellular acting) for a long time, vaccine available but rarely used

Legionella general characteristic

Weakly gram -, motile, pleomorphic in life cycle, very fastidious

legionella epidemiology

specific resevoir unknown, widely distributed in water, outbreaks sporadic, warm temps allow growth

Legionella virulence

capable of intracellular growth

Legionella clinical disease

Legionellosis (Legionnaire’s disease): initial flu like, diarrhea, leads to pneumonia, becomes systemic quickly

Pontiac fever: same but no pneumonia

Legionella lab identification

diagnosis through patient history/symptomology, fluorescent antibody staining, DNA probes, growth on charcoal yeast agar

Legionella treatment

Azithromycin, clarithromycin, quinolones