Isolation and characterisation of Acinetobacter species clinical isolates from Terengganu, Malaysia
Acinetobacter spp. have become one of the top nosocomial pathogens of concern causing a wide spectrum of infections including bloodstream, urinary and respiratory tract. Increasing prevalence of multidrug resistance (MDR-resistance to three or more antimicrobial group) has become a very serious heal...
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| Format: | Thesis Book |
| Language: | English |
| Published: |
2018.
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| Summary: | Acinetobacter spp. have become one of the top nosocomial pathogens of concern causing a wide spectrum of infections including bloodstream, urinary and respiratory tract. Increasing prevalence of multidrug resistance (MDR-resistance to three or more antimicrobial group) has become a very serious health concern among Acinetobacter spp., particularly carbapenem resistance. Acinelobacter spp. is difficult to identify to the species level using standard biochemical and phenotypic tests. Hence, there is a lack of data regarding the prevalence of drug resistance among A. baumannii (which is the main Acinetobacter species causing serious infections) and non-baumannii Acinetobacter species in Malaysia. This study aims to characterize Acinetobacter spp. isolates from Terengganu, Malaysia, particularly their drug resistance profiles and carriage of resistance genes. One hundred and fifty-three Acinetobacter spp. isolates were collected from the microbiology laboratory of Hospital Sultanah Nur Zahirah (HSNZ) in Kuala Terengganu throughout 2015. All isolates were initially differentiated into A. baumannii and non-baumannii Acinetobacter spp. by amplification of 16S ribosomal DNA restriction analysis (ARDRA) with five different restriction enzymes iHha), Alul, Mbol, Rsal, and Mspl). Identification of the non-baumannii acinetobacters at the species level was performed by sequencing of ribosomal polymerase bela subunit (rpoB) andl6S ribosomal ribonucleic acid (/6S rRNA) genes. Antibiotic susceptibility tests were performed with 16 antimicrobial agents by the disc diffusion method. The minimum inhibitory concentration for irnipenern, meropenem, and tigecycline were determined using E-strips. The isolates were also screened for the presence of six main carbapenem-resistance genes (intrinsic blaoXA.51, acquired blaoxs-n, blaoXA.24, blaoxs.s«, blaV1M, and blalMI') by polymerase chain reaction (PCR). The upstream of ISAbal towards blaoXA.51 and blaoXA-23 genes were also investigated by PCR detection. ARDRA revealed that 83.7% (n= 128) of the isolates were Acinetobacter baumannii while the rest were grouped as tvstv-baumannii genospecies. The rate of MDR among all Acinetobacter spp. isolates was 56.2% (n=86) with a vast majority (98%; n=85) being A. baumannii. Overall, the isolates showed moderate resistance rates (between 60%-70%) to amikacin, gentamicin, irnipenern, meropenern, doripenem, ciprofloxacin, piperacillin¬tazobactam, ticarcillin-clavulanate, cefotaxime, cefuroxime, ceftazidime, cefepime, ampicillin-sulbactam, and tetracycline. All isolates were susceptible to polymyxin B, colistin, and tigecycline, considered the drugs of last resort for carbapenern-resistant Acinetobacter infections. Carbapenern resistance rates were higher among A. baumannii (68.8%) as compared to non-baumannii Acinetobacter isolates (8.0%). Screening for carbapenemase-encoding genes by PCR revealed that 98% of the isolates harboured the blaoxs-s, gene, 56.2% harboured btooxs-n, 4.6% with blaoXA. 24, and 2% carried blaoXA-58 gene. A. baumannii isolates harbouring ISAbaJ-blaoXA.23 (70.5%) were significantly associated with resistance towards carbapenems (p<0.00 I), due likely to the ISAbal element providing an external promoter for the increased expression of the blaOXA-23 gene. The acquired blaoXA-23 gene was largely responsible for carbapenem resistance in the clinical A. baumannii isolates from H NZ and warrants continuous surveillance to prevent its further dissemination. The existence of a small number of non-baumannii Acinetobacter clinical isolates should be closely monitored and antimicrobial drug usage in the hospital carefully controlled to prevent the development and spread of MDR strains of both A. baumannii and other distinctive non-baumannii Acinetobacter genospecies. |
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| Physical Description: | xviii, 126 leaves: illustrations (some colour); 30 cm. |
| Bibliography: | Includes bibliographical references (p. 96-112) |