19 Opportunistic Gram Negatives Flashcards
T/F- Almost any pathogen that can grow at 37 degrees can cause an opportunistic infection
True
Characteristics of Klebsellia?
- Opportunistic enterobacteriacea
- Gram negative non-motile rod
- Prominent mucoid capsule enhances virulence
- Lactose positive
What are the two most common species of Klebsiella isolated from medical patients?
K. pneumoniae
K. oxytoca
T/F- Antibiotic resistance is not a significant problem in Klebsiella
False. Select Klebsiellas produce extended spectrum beta lactamases (ESBLs) and are resistant to many antibiotics. Choose antibiotic treatment based on local susceptibility patterns.
Symptoms of Klebsiella infection?
fever
productive cough (often blood tinged)
May cause community acquired or hospital acquired pneumonia
T/F- Klebsiella has a low mortality rate
False. A high mortality rate (over 50% even with Antibiotic treatment) is observed, likely due to the underlying concomitant medical conditions
Characteristics of Proteus species?
- gram neg. rod
- swarming motility
- lactose negative
- urease positive
Which species of proteus causes 90% of all proteus infections?
P. mirabilis
What are the typical infections caused by proteus?
UTI wound septicemia pneumonia (These mostly occur in hospitalized patients)
What organism causes urinary stones (struvite)? And how?
Proteus produces high levels of urease=>hydrolyzes urea to ammonia=>increased alkalinity=>precipitates Mg and Ca
Characteristics of Pseudomonas aeruginosa?
- Gram negative aerobic motile rod
- oxidase positive
- non fermenting (unlike enterobacteriacieae)
- mucoid exopolysaccharide (slime layer)
- grape-like odor
- blue-green pus
Does pseudomonas aeruginosa produce any pigments? If so, which ones?
Yes -pyocyanin: blue pigment -pyoverdin: yellow pigment (siderophore) -pyorubrum: red pigment. REMEMBER P. cepacia (Burkholderia cepacia) does not produce pigments!
Where is pseudomonas found?
soil, water, plants
What groups of patients are especially at risk for pseudomonas opportunistic infection? What are common infections?
- Burn patients (can’t bring plants into burn unit), cystic fibrosis
- swimmer’s ear (otitis externa), septicemia, pneumonia.
T/F- Lungs of most children w/ cystic fibrosis become colonized with P. aeruginosa before the age of 10
True
T/F- Pseudomonas bacteria have not yet acquired many antibiotic resistant genes
False
Pseudomonas tend to form biofilms, how does this protect the bacteria?
Increased adhesion, immune evasion, and interferes with antibiotic treatment. They express new genes when biofilm forms!
Burkholderia cepacia is related to P. aeruginosa. What type of infection is it associated with?
lung infections in CF patients
What type of people are associated with Stenotrophomonas maltophila (p. maltophila) infections?
Hospital patients
HIV patients
immunocompromised patients
Characteristics of Acinetobacter baumannii?
- Gram negative, non-motile rod
- Oxidase negative
- Strict aerobe
- Utilizes organic compounds other than sugars as a carbon source
T/F- A rapidly increasing problem in hospitals and soldiers coming home from iraq/afghanistan wars is infection with multiply-resistant strains of acinetobacter baumanni?
True
T/F- Gram negative rods (enterobacteria and others) are most frequently associated with infections of compromised hosts and cause a variety of infections (UTI, RTI, sepsis, device infections)?
True
T/F Gram negative rods (enterobacteria and others) can be difficult to treat due to antibiotic resistance?
True
T/F Gram negative rods (enterobacteria and others) are not frequently found in the environment?
False
Do gram positive bacteria grow on MacConkey agar?
No
T/F- enterobacteriaceae are oxidase positive?
False, they are all oxidase negative
