Dissemination ofbla_OXA-23,bla_OXA-24,bla_OXA-58, andbla_NDM-1Genes ofAcinetobacter baumanniiIsolates from Four Tertiary Hospitals in Thailand

Abstract

Acinetobacter baumannii is a major threat to public health due to the emergence and dissemination of antibiotic-resistant strains. The purpose of this study was to determine the molecular epidemiology of antibiotic-resistant A. baumannii isolates collected from four tertiary hospitals in Thailand during the period November 2013-February 2015. We screened 339 A. baumannii, nonrepetitive clinical isolates to determine drug susceptibility. Among all isolates, we found that 7.9% was nondrug-resistant A. baumannii (NR-AB). Carbapenem-resistant A. baumannii (CR-AB) strains accounted for 84.9% of the total isolates, with extensively drug-resistant A. baumannii (XDR-AB) accounting for 7.9% of the total isolates. We further investigated class D carbapenemase genes using multiplex-PCR amplification and class B metallo-β-lactamase genes, including bla, bla, and bla genes, using PCR and sequencing methods. We found that 300 (88.5%) isolates carried acquired class D carbapenemase genes, including bla (82.6%), bla (0.3%), and bla (6.5%). The genes bla and bla were not detected in any isolates. The bla was detected in 31 isolates from two hospitals (9.1%). All of the bla-positive A. baumannii (NDM-AB) had ISAba125 sequences upstream of the bla gene. A coexistence of three resistance genes-bla-bla-bla-was found in one isolate. A repetitive element palindromic-PCR (REP-PCR) revealed that all A. baumannii isolates were genetically diverse and could be divided into 33 genotypes. Only three genotypes were found to be predominant in all hospitals. Data from our study indicate the widespread emergence of multiple resistance determinants in A. baumannii isolates in Thailand, suggesting the need for more stringent infection control measures.

Overproduction of efflux pumps caused reduced susceptibility to carbapenem under consecutive imipenem-selected stress in <em>Acinetobacter baumannii</em>

“…According to Ambler’s classification for β -lactamases, the main carbapenemases, bla NDM-1 (B group), bla OXA-23-like , bla OXA-24-like , bla OXA-51-like , and bla OXA-58-like (D group) genes were detected according to previously established polymerase chain reaction (PCR) reaction mixture and thermal conditions. 10 , 27 The detection of ISA ba1 / bla OXA-51-like gene combination was made referring to the method of Turton et al 8 A. baumannii reference strain ATCC 17978 and three A. baumannii isolates (ab606, ab608, and ab609 [carrying bla OXA-58-like , bla OXA-23-like , and bla OXA-24-like genes, respectively]) were used as the quality control strains for the detection of carbapenemases.…”

The Current Burden of Carbapenemases: Review of Significant Properties and Dissemination among Gram-Negative Bacteria

“…OXA-24 was subsequently named OXA-40, and additional members of the group, namely OXA-25, OXA-26, OXA-72, and OXA-160 were subsequently discovered [125]. While the OXA-24 group is documented in A. baumannii in reports from certain countries like Taiwan [138], Thailand [139], Bulgaria [140], and Lebanon [141], it was also detected in P. aeruginosa [142] in one French study. It was previously thought that bla OXA-24-like genes are mainly located on chromosomes and no mobile elements are associated.…”

Investigating Bacteriophages Targeting the Opportunistic Pathogen Acinetobacter baumannii

“…Bacteriophages, previously isolated from wastewater at Buddhachinaraj and Bang Rakam hospitals, were screened against multidrug resistant (MDR) A. baumannii strains [22] from five tertiary hospitals (HA-HE, see methods) (where MDR-AB is defined as strains resistant to at least three classes from penicillins/cephalosporins, fluroquinolones, and aminoglycosides [23,24]). The five of these bacteriophages with the highest host range were carried forward for further investigation in this study (Table 1 and Figure 1).…”

“…These bacteriophages are now called vB_AbaM_PhT2, vB_AbaM_PhT4, vB_AbaP_PhT29, vB_AbaP_PhT39, and vB_AbaM_PhT44 (previously ØAB02, ØAB04, ØAB29, ØAB39 and ØAB44), but for the purposes of the flow of the text in this paper, these names have also been abbreviated to vPhT2, vPhT4, vPhT29, vPhT39, and vPhT44 respectively [30]. Bacteriophages, previously isolated from wastewater at Buddhachinaraj and Bang Rakam hospitals, were screened against multidrug resistant (MDR) A. baumannii strains [22] from five tertiary hospitals (HA-HE, see methods) (where MDR-AB is defined as strains resistant to at least three classes from penicillins/cephalosporins, fluroquinolones, and aminoglycosides [23,24]). The five of these bacteriophages with the highest host range were carried forward for further investigation in this study (Table 1 and Figure 1).…”

“…Seventeen bacteriophages were isolated from wastewater at Buddhachinaraj and Bang Rakam hospitals in Phitsanulok province, Thailand in 2010 and were screened against 150 MDR A. baumannii strains collected from five hospitals [11,22,27,29] using a spot test method as described previously [27]. For additional information on the chosen bacteriophages and MDR-AB, please refer to the supplement file: 'Selected-MDRAB-150-isolates'.…”