Miscellaneous Gram Neg Rods Flashcards
GNRs predominately cause what type of infections?
opportunistic infections in a debilitated host.
What do GNRs grow on?
BAP and CHOC and therefore will be detected on routine bacterial culture. (growth on Mac is variable)
How are these organisms identified?
- glucose utilization: O, or inert, inactive, asacharolytic
- Oxidase: most are positive
- Ability to grow on Mac: variable
- nonfermenters
Are they easy to treat?
They can be very difficult to treat and they develop resistance quickly. they can also take a long time to ID
What is the most commonly isolated non fermenting GNR?
psuedomonas
Does psuedomonas require special places to live?
NO! it can grow just about anywhere. soap, sink, treatment pools, mechanical ventilators, dialysis equipment. and it is aerobic, it requires o2 for growth.
What makes someone susceptible to pseudomonas aeruginosa?
1 treatment with broad spectrums that decrease normal flora 2. use of mechanical ventilation equipment.
Where can colonization of P. aeruginosa occur?
Upper resp tract, skin, GI tract.
What are some features of P. aeruginosa that make it hard to kill?
It has many virulence factors, and it secretes many enzymes and toxins that destroy tissue. It is also resistant to many antibiotics.
What antibiotics is P. aeruginosa resistant to?
PCN, amp/amox, ceph:1 and 2 gen. resistance can develop quickly among beta-lactams
Who do we see P. aeruginosa infections in most commonly?
CF patietns, immunosuppressed, burn wounds, osteomyelitis, UTI, septicemia, corneal ulcers, swimmer’s ear, folliculitis.
What is the unique smell of P. aeruginosa infections?
grape smell.
What are the interim results you might get while wating for the psuedomonas culture to come back (growth takes 18-24 hours)
non-lactose fermenting GNR, oxidase positive
What GNR can survive for months on fomites, and is NF in the skin and vaginal tract?
Acinetobacter sp.
Where does Acinteobacter sp live?
in the soil, water…it can survive for months on fomites.
Where is Acinteobacter sp NF?
skin and vaginal tract.
What Acinteobacter sp is very resistant to antibiotics and was seen in wound infections of personnel from Iraq?
Acinteobacter baumannii
What is the DOC for tx of Acinteobacter baumannii
carbapenams: resistance increasing, or colistin and polymixin B: resistance documented.
What are the interim results you might get while wating for the acinetobacter culture to come back (growth takes 24-72 hours
gram stain: plump gnr in pairs
interim report: non-lactose fermenting gnr, oxidase negative.
grows on Mac
What is the 3rd most common GNR non fermenter isolated in the lab?
Stentotrophomonas maltophilia
Where can Stentotrophomonas maltophilia be found?
ubiquitous in nature, water sources. usually not considered normal flora, but patients become colonized in the hospital. noscomial infections. opportunistic.
Stentotrophomonas maltophilia has (high/low) virulence factors?
low
what infections does Stentotrophomonas maltophilia most often cause?
bacteremia and pnuemonia
What is Stentotrophomonas maltophilia most resistant to?
cephalosporins, aminoglycosides, carbapenams
Who are patients at risk of a Stentotrophomonas maltophilia infection?
broad spectrum abx tx, catheters, mechanical ventilators, CF patients
what would the interim report for Stentotrophomonas maltophilia say?
growth normally occurs in 24-48 hours on routine media.
Interim report: non lactose fermenting GNR, oxidase neg.
What are the DOC for Stentotrophomonas maltophilia
SXT, ticarcillin-clauvanate, Ticarbillin-clauvanate + aztreonam
