Molecular epidemiology and characterization of resistance mechanisms to various antimicrobial agents in Acinetobacter baumannii isolated in Mérida, Venezuela.
BACKGROUND
A. baumannii outbreaks are difficult to control because of the relative ease with which this microorganism spreads and persists in hospital settings. Successive papers reported increased resistance in clinical isolates of A. baumannii, currently resistant to most antibiotics. The purpose of this study was to characterize the epidemiological relationship and the mechanisms of resistance to several antimicrobial agents of a collection of A. baumannii strains.


METHODS
Twenty A. baumannii isolated from two intensive care units (ICUs) at the Instituto Autónomo Universitario de Los Andes, Mérida, Venezuela, were analyzed by PFGE. Characterization of resistance determinants to various antimicrobial agents was also carried out.


RESULTS
PFGE typing revealed five different patterns. Pattern 1, susceptible to ciprofloxacin and cefepime, was found to be spread among the patients of both ICUs and was also cultured from a humidifier in the neonatal ICU. All the strains were resistant to gentamicin and tetracycline, 90% to amikacin and cefotaxime, and 85% to ciprofloxacin. The resistance of the strains to ceftazidime, cefepime, and imipenem was 40, 50, and 10%, respectively. All the strains showed beta-lactamases with Ips equal to 5.4 (TEM-1) and greater than 9. Furthermore, two of them, both exhibiting resistance to imipenem, presented a beta-lactamase with an Ip of 7.2 (OXA-58). Three of seven amikacin-resistant A. baumannii strains (PFGE-2) carried the gene encoding the APH(3')-Vla enzyme and two strains (PFGE-5) had the TET(B) determinant.


CONCLUSIONS
This study shows the dissemination of A. baumannii clinical isolates, a humidifier being the source of the strain.
Salazar De Vegas
Elsa Zuleima
EZ
Department of Bioanalysis, Bacteriology Laboratory, University of Oriente, Sucre Campus, Venezuela. elsazul2003@cantv.net
Nieves
Beatriz
B
Ruiz
Marc
M
Ruíz
Joaquim
J
Vila
Jordi
J
María
Araque
A
Elsa
Velázco
V
D000151:Acinetobacter Infections / Q000453:epidemiology*; D040981:Acinetobacter baumannii / Q000187:drug effects* / Q000235:genetics; D000328:Adult; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D000077723:Cefepime; D002511:Cephalosporins / Q000494:pharmacology; D002939:Ciprofloxacin / Q000494:pharmacology; D017931:DNA Primers / Q000235:genetics; D004196:Disease Outbreaks; D024901:Drug Resistance, Multiple, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D005798:Genes, Bacterial / Q000235:genetics; D005839:Gentamicins / Q000494:pharmacology; D006801:Humans; D015378:Imipenem / Q000494:pharmacology; D007231:Infant, Newborn; D013754:Tetracyclines / Q000494:pharmacology; D014687:Venezuela / Q000453:epidemiology; D001618:beta-Lactamases / Q000378:metabolism
D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D017931:DNA Primers; D005839:Gentamicins; D013754:Tetracyclines; D002939:Ciprofloxacin; D015378:Imipenem; D000077723:Cefepime; D001618:beta-Lactamases