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Extensively drug-resistant Acinetobacter baumannii (XDR-AB) is a major threat to public health worldwide. A retrospective study for 27 XDR-AB isolates from four tertiary hospitals in Thailand was conducted. Beta-lactamase and virulence genes were characterized by PCR. The bla ADC , bla OXA-51 , and bla OXA-23 were detected in all isolates, whereas bla PER-1 and bla NDM-1 genes were present in 7.4% and 3.7% of isolates. All isolates had virulence genes, including genes in iron acquisition system, biofilm formation and secretion systems. The plasmids in XDR-AB belonged to GR2 (100%), GR6 (40.7%), and GR1 (7.4%). Multilocus sequence typing sequence types (STs) were further investigated. The data demonstrated that XDR-AB isolates had nine STs: ST195 ( n  = 4), ST208 ( n  = 4), ST368 ( n  = 1), ST451 ( n  = 5), ST457 ( n  = 2), ST1947 ( n  = 1), ST1166 ( n  = 7), including two novel STs namely ST1682 ( n  = 2) and ST1684 ( n  = 1). We observed that the majority ST1166 (25.9%) was associated with the prevalence of GR2 and GR6 plasmids and tr a U virulence gene. Genome-based single nucleotide polymorphism phylogenetic analysis of the isolates with two novel ST types indicated that the two isolates belonged to the international clone II (IC2) within the same cluster. In conclusion, our data showed the dissemination of XDR-AB isolates harbored virulence genes and antibiotic resistance genes among four hospitals in Thailand. The results highlighted the difficulty posed for the empirical treatment of the patients with the A. baumannii infection.

Dissemination of mcr-1 encoding colistin resistance in Gram-negative bacteria has created critical situation in poultry, livestock farming, and public health. In Nepal, for the first time, we initiated surveillance of colistin-resistant Escherichia coli in broilers from seven different chicken farms. A total of 324 cloacal swabs were collected and 118 E. coli were isolated, of which 27 (22.8%) were colistin resistance all harboring mcr-1 gene, but lacking IS ApI1 . Colistin-resistant isolates were characterized by antibiotic susceptibility testing, detecting antibiotic resistance genes, phylogenetic analysis, and plasmid replicon typing. These isolates belonged to the phylo-group A (70.37%) and phylo-group D (29.63%). In addition, most isolates (>80%) were resistant to ciprofloxacin, tetracycline, and sulfamethoxazole-trimethoprim. As much as 3 of the 27 mcr-1 encoding isolates were confirmed as extended-spectrum β-lactamase (ESBL) producer, all 3 isolates carrying bla CTX-M gene. We performed the conjugation experiment to check transferability of mcr-1 , tet , and bla CTX-M genes, and only two donors were found to have transferred resistance to ticarcillin. The transfer of colistin and tetracycline resistance was not detected, which suggests the chromosomal location of mcr-1 and tet genes. The prevalence of Inc K/B and Inc I1 was 96.3% and 81.48%, respectively. This study shows the co-existence of mcr-1 with tet , sul , qnr , dfr , and bla CTX-M genes and dissemination of these resistant isolates in Nepalese chicken farms, which may pose huge threat to the livestock, especially chickens, and public health in Nepal.

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 IMP , bla VIM , and bla NDM-1 genes, using PCR and sequencing methods. We found that 300 (88.5%) isolates carried acquired class D carbapenemase genes, including bla OXA-23 (82.6%), bla OXA-24 (0.3%), and bla OXA-58 (6.5%). The genes bla IMP and bla VIM were not detected in any isolates. The bla NDM-1 was detected in 31 isolates from two hospitals (9.1%). All of the bla NDM-1 -positive A. baumannii (NDM-AB) had ISAba125 sequences upstream of the bla NDM-1 gene. A coexistence of three resistance genes-bla OXA-23 -bla OXA-58 -bla NDM-1 -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.