Molecular characterization of carbapenemase and cephalosporinase genes among clinical isolates of Acinetobacter baumannii in a tertiary medical centre in Malaysia.
Antimicrobial resistance in Acinetobacter baumannii is a growing public health concern and an important pathogen in nosocomial infections. We investigated the genes involved in resistance to carbapenems and cephalosporins in clinical A. baumannii isolates from a tertiary medical centre in Malaysia. A. baumannii was isolated from 167 clinical specimens and identified by sequencing of the 16S rRNA and rpoB genes. The MIC for imipenem, meropenem, ceftazidime and cefepime were determined by the E-test method. The presence of carbapenemase and cephalosporinase genes was investigated by PCR. The isolates were predominantly nonsusceptible to carbapenems and cephalosporins (>70 %) with high MIC values. ISAba1 was detected in all carbapenem-nonsusceptible A. baumannii harbouring the blaOXA-23-like gene. The presence of blaOXA-51-like and ISAba1 upstream of blaOXA-51 was not associated with nonsusceptibility to carbapenems. A. baumannii isolates harbouring ISAba1-blaADC (85.8 %) were significantly associated with nonsusceptibility to cephalosporins (P<0.0001). However, ISAba1-blaADC was not detected in a minority (<10 %) of the isolates which were nonsusceptible to cephalosporins. The acquired OXA-23 enzymes were responsible for nonsusceptibility to carbapenems in our clinical A. baumannii isolates and warrant continuous surveillance to prevent further dissemination of this antibiotic resistance gene. The presence of ISAba1 upstream of the blaADC was a determinant for cephalosporin resistance. However, the absence of this ISAba1-blaADC in some of the isolates may suggest other resistance mechanisms and need further investigation.
Department of Medical Microbiology and Immunology, Universiti Kebangsaan Malaysia Medical Centre, Jalan Yaacob Latif, Bandar Tun Razak, 56000 Cheras, Kuala Lumpur, Malaysia.
Shirin
S
Biglari
Department of Medical Microbiology and Immunology, Universiti Kebangsaan Malaysia Medical Centre, Jalan Yaacob Latif, Bandar Tun Razak, 56000 Cheras, Kuala Lumpur, Malaysia.
Hanafiah
H
Alfizah
Department of Medical Microbiology and Immunology, Universiti Kebangsaan Malaysia Medical Centre, Jalan Yaacob Latif, Bandar Tun Razak, 56000 Cheras, Kuala Lumpur, Malaysia.
Ramli
R
Ramliza
Department of Medical Microbiology and Immunology, Universiti Kebangsaan Malaysia Medical Centre, Jalan Yaacob Latif, Bandar Tun Razak, 56000 Cheras, Kuala Lumpur, Malaysia.
Md Mostafizur
MM
Rahman
D000151:Acinetobacter Infections / Q000382:microbiology*; D040981:Acinetobacter baumannii / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001426:Bacterial Proteins / Q000235:genetics*; D015780:Carbapenems / Q000494:pharmacology; D002510:Cephalosporinase / Q000235:genetics*; D002511:Cephalosporins / Q000494:pharmacology; D002648:Child; D002675:Child, Preschool; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D012321:DNA-Directed RNA Polymerases / Q000235:genetics; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008296:Malaysia; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D062606:Tertiary Care Centers; D055815:Young Adult; D001618:beta-Lactamases / Q000235:genetics*
D001426:Bacterial Proteins; D015780:Carbapenems; D002511:Cephalosporins; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S; D012321:DNA-Directed RNA Polymerases; C105078:RNA polymerase beta subunit; D002510:Cephalosporinase; D001618:beta-Lactamases; C063912:carbapenemase