[Interpretative reading of the non-fermenting gram-negative bacilli antibiogram].
Among non-fermenting Gram-negative rods, the most clinically important species are Pseudomonas aeruginosa, Acinetobacter baumannii, and Stenotrophomonas maltophilia, which are frequently multiresistant. P. aeruginosa resistance to beta-lactams depends on the production of chromosomal and plasmid-mediated beta-lactamases, altered permeability (loss of OprD porin is related to carbapenem-resistance) and active efflux pumps, particularly MexAB-OprM. In aminoglycoside-resistant strains the main mechanism of resistance is the production of inactivating enzymes; the efflux pump MexXY-OprM is also involved. Quinolone-resistance in P. aeruginosa is related to changes in topoisomerases, altered permeability and efflux pumps. The mechanisms of resistance of A. baumannii have not been well characterized, which makes interpretative reading of the antibiogram in this organism difficult. Resistance to beta-lactams is associated with the production of beta-lactamases and altered penicillin-binding proteins. Resistance to aminoglycosides has been related to modifying enzymes and resistance to quinolones to altered targets. S. maltophilia is resistant to carbapenems and other beta-lactams because of the production of two beta-lactamases (L-1 and L-2). Aminoglycoside-modifying enzymes have also been described in this species. In contrast to what is observed in other organisms, S. maltophilia resistance to quinolones has been mainly related to active efflux, rather than to target alterations.
Vila
Jordi
J
Servicio de Microbiología, Institut d'Infeccions i Immunologia, Hospital Clínic i Provincial, Barcelona, España. jvilaestape@yahoo.com
Marco
Francesc
F
D000150:Acinetobacter / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D000617:Aminoglycosides; D000900:Anti-Bacterial Agents / Q000378:metabolism / Q000494:pharmacology; D000890:Anti-Infective Agents / Q000378:metabolism / Q000494:pharmacology; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000502:physiology; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology; D001693:Biological Transport, Active / Q000235:genetics; D015780:Carbapenems / Q000378:metabolism / Q000494:pharmacology; D002352:Carrier Proteins / Q000235:genetics / Q000502:physiology; D024881:Drug Resistance, Bacterial / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D005285:Fermentation; D024841:Fluoroquinolones; D008826:Microbial Sensitivity Tests; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D020615:Stenotrophomonas maltophilia / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D001618:beta-Lactamases / Q000235:genetics / Q000502:physiology
D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D015780:Carbapenems; D002352:Carrier Proteins; D024841:Fluoroquinolones; D001618:beta-Lactamases