Gram Negative Bacilli Flashcards
What are the two gram neg bacilli most responsible for nosocomial infection?
Escherichia Coli
Pseudomonas Aeruginosa
In what environments is Pseudomonas Aeruginosa often found?
Water and soil
What factors contribute to gram negative bacilli being pathogenic?
Able to survive in harsh environments
Grow with minimal nutrition
(can grow in antiseptic solutions)
What does Pseudomonas Aeruginosa release to inhibit growth of competing microbes?
antimicrobial substances
This is similar in Acinetobacter - assoc w/ ICU outbreaks
What host factors increase the propensity of colonization by gram negative bacilli?
General debilitation of pt
Use of invasive procedures that breakdown normal host barriers
Depletion of fibronectin
Antibiotic therapy that eradicates normal flora
What host microbial determinants increase the propensity of colonization by gram negative bacilli?
(enhance attachment to host cells)
Pili or fimbriae
Production of glycocalyx or slime
Production of extracellular enzyme breads down cell barriers and prevent host response
What is the best way to prevent or minimize colonization in hospitalized patients?
Hand washing
Appropriate cleaning and disinfection of med equip
Antimicrobial stewardship
What are the two most common mechanisms of antimicrobial resistance in gram negative bacilli?
Extended Spectrum Beta-Lactamase (ESBL)
Carbapenemase Producing Organisms (CPO)
What are ESBLs?
Enzymes that break down broad spectrum beta lactam antibiotics (e.g. penicillin, cepholosporins)
But don’t break down carbapenems ( meropenem, imipenem)
Can ESBLs be transmitted between bacteria?
Yes, plasmid mediated
Which gram negative bacilli have ESBLs been found in?
E. coli
Klebsiella pneumoniae
citrobacter
enterobacter
These organisms commonly cause UTIs
What are CPOs?
Carbapenemase Producing Organisms
Gram-negative organisms resistant to carbapenems (meropenem, imipenem)
Produce carbapenemase enzymes
these enzymes hydrolyze all beta lactam antibiotics
Which organisms have CPO been found in?
E. coli
Klebsiella pneumoniae
Pseudomonas spp
Can CPO be transmitted between bacteria?
Yes, via plasmids
Which other antibiotics is CPO resistant to?
Generally resistant to almost all classes of antimicrobials
