Genomic characterization of antibiotic resistance-encoding genes in clinical isolates of Vibrio cholerae non-O1/non-O139 strains from Kolkata,India: generation of novel types of genomic islands containing plural antibiotic resistance genes

Non-O1/non-O139 nontoxigenic Vibrio cholerae associated with cholera-like diarrhea has been reported in Kolkata, India. However, the property involved in the pathogenicity of these strains has remained unclear. The character of 25 non-O1/non-O139 nontoxigenic V. cholerae isolated during 8 years from 2007 to 2014 in Kolkata was examined. Determination of the serogroup showed that the serogroups O6, O10, O35, O36, O39, and O70 were represented by two strains in each serogroup, and the remaining isolates belonged to different serogroups. To clarify the character of antibiotic resistance of these isolates, an antibiotic resistance test and the gene analysis were performed. According to antimicrobial drug susceptibility testing, 13 strains were classified as drug resistant. Among them, 10 strains were quinolone resistant and 6 of the 13 strains were resistant to more than three antibiotics. To define the genetic background of the antibiotic character of these strains, whole-genome sequences of these strains were determined. From the analysis of these sequences, it becomes clear that all quinolone resistance isolates have mutations in quinolone resistance-determining regions. Further research on the genome sequence showed that four strains possess Class 1 integrons in their genomes, and that three of the four integrons are found to be located in their genomic islands. These genomic islands are novel types. This indicates that various integrons containing drug resistance genes are spreading among V. cholerae non-O1/non-O139 strains through the action of newly generated genomic islands.     

Case report of clinical salmonellosis by Salmonella Typhimurium that occurred in Portuguese children

Aims: Aim of this study is to characterize clinical isolates of Salmonella Typhimurium that occurred in Portuguese children on the basis of their virulence and antimicrobial resistance profiles and pulsed‐field gel electrophoresis typing and to analyse possible strain relatedness. Methods and Results: Different Salmonella serotypes were isolated from clinical cases of salmonellosis that had occurred in two Portuguese hospitals (a total of 259 isolates). All Salm. Typhimurium strains, with the age of the patients known, (total of 26 isolates) were selected for this study. These isolates were characterized for their virulence gene profiles (agfA, iroB, slyA, hin/H2, spv), antimicrobial resistance profiles and investigated for the occurrence of multidrug‐resistant Salm. Typhimurium DT 104 by PCR. Salmonella isolates showed high rates of resistance to four or more antibiotics, 100% resistance to sulfadiazine and a high percentage of strains with the resistance profile of Salm. Typhimurium DT 104, two of them with this phage type (determined by PCR). A relationship between some clusters and their resistance and virulence profiles was detected, each cluster having the same profile. Conclusions: This study showed high‐antibiotic resistance of the Salmonella strains investigated, and the presence of multidrug‐resistant Salm. Typhimurium DT104 in infections of Portuguese children. Significance and Impact of the Study: Study is based on regarding the increase in antibiotic resistance by Salmonella strains isolated from infections in Portuguese children and on the presence of Salm. Typhimurium DT 104 circulating in Portugal.     

Prevalence and antimicrobial resistance in Salmonella enterica isolated from broiler chickens,pigs and meat products in Thailand–Cambodia border provinces

This study aimed to examine the prevalence and antimicrobial resistance (AMR) of Salmonella isolates from broiler chickens, pigs and their associated meat products in the Thailand–Cambodia border provinces. A total of 941 samples were collected from pigs and broiler chickens at slaughter houses and from carcasses at local fresh markets in Sa Kaeo, Thailand (n = 554) and Banteay Meanchey, Cambodia (n = 387) in 2014 and 2015. From these samples, 345 Salmonella isolates were collected from Sa Keao (n = 145; 23%) and Banteay Meanchey (n = 200; 47%) and assayed for antimicrobial susceptibility, class 1 integrons and extended‐spectrum β‐lactamase (ESBL) genes. Serovars Typhimurium (29%) and Rissen (29%) were the most common serotypes found in Thai and Cambodian isolates, respectively. Multidrug resistance was detected in 34% and 52% of isolates from Sa Keao and Banteay Meanchey, respectively. The majority of the Thai isolates were resistant to ampicillin (72.4%), whereas most Cambodian isolates were resistant to sulfamethoxazole (71%). Eleven isolates from Sa Keao and 44 from Banteay Meanchey carried class 1 integrons comprising resistance gene cassettes. The most common gene cassette array was dfrA12‐aadA2 (61.1%). Six isolates were ESBL producers. The β‐lactamase genes found included bla_TEM‐1, bla_CTX‐M‐55 and bla_CMY‐2. Some of these class 1 integrons and ESBL genes were located on conjugative plasmid. In conclusion, multidrug‐resistant Salmonella are common in pigs, chickens and their products in the Thailand–Cambodia border provinces. Our findings indicate that class 1 integrons play a role in spread of AMR in the strains in this study.     

Molecular characterization of antimicrobial resistance in Salmonella isolated from animals in Japan

Aims:  To investigate the prevalence of integrons and antimicrobial resistance genes in Salmonella recovered from animals in Japan.
Methods and Results:  Forty-eight out of ninety-four (51·1%) Salmonella isolates showed multidrug resistance phenotypes and harboured at least one antimicrobial resistance gene. Twenty-two out of forty-seven (46·8%) Salmonella enterica serovar Typhimurium that were multidrug-resistant were of definitive phage type DT104. Class 1 integrons were identified in 34/94 isolates (36·2%): 21 isolates containing two gene cassettes, aadA2 and bla _PSE–1, and 13 containing one gene cassette, aadA1 , aadA2 or bla _PSE–1. Class 2 integrons containing estX - sat2 - aadA1 gene cassettes were only identified in Salmonella Enteritidis. The β-lactamase-encoding gene, bla _TEM, was only detected in S. Typhimurium. The plasmid-mediated quinolone resistance gene, qnrS1 , was identified in S. Typhimurium and Salmonella Thompson.
Conclusions:  Our results characterized integrons and antimicrobial resistance genes in Salmonella of animal origin. To the best of our knowledge, this is the first report of qnrS in Salmonella from Japan and also the first report of qnrS in S . Thompson.
Significance and Impact of the Study:  Little is known about the molecular basis of antimicrobial resistance in Salmonella isolated from animals. This study provides useful data on the incidence of integrons and resistance genes in Salmonella of animal origin.     

Phenotypic and genotypic analysis of bacteria isolated from three municipal wastewater treatment plants on tetracycline‐amended and ciprofloxacin‐amended growth media

Aims: The goal of this study was to determine the antimicrobial susceptibility of bacteria isolated from three municipal wastewater treatment plants. Methods and Results: Numerous bacterial strains were isolated from three municipal wastewater treatment facilities on tetracycline‐ (n = 164) and ciprofloxacin‐amended (n = 65) growth media. These bacteria were then characterized with respect to their resistance to as many as 10 different antimicrobials, the presence of 14 common genes that encode resistance to tetracycline, the presence of integrons and/or the ability to transfer resistance via conjugation. All of the characterized strains exhibited some degree of multiple antimicrobial resistance, with nearly 50% demonstrating resistance to every antimicrobial that was tested. Genes encoding resistance to tetracycline were commonly detected among these strains, although intriguingly the frequency of detection was slightly higher for the bacteria isolated on ciprofloxacin‐amended growth media (62%) compared to the bacteria isolated on tetracycline‐amended growth media (53%). Class 1 integrons were also detected in 100% of the queried tetracycline‐resistant bacteria and almost half of the ciprofloxacin‐resistant strains. Conjugation experiments demonstrated that at least one of the tetracycline‐resistant bacteria was capable of lateral gene transfer. Conclusions: Our results demonstrate that multiple antimicrobial resistance is a common trait among tetracycline‐resistant and ciprofloxacin‐resistant bacteria in municipal wastewater. Significance and Impact of the Study: These organisms are potentially important in the proliferation of antimicrobial resistance because they appear to have acquired multiple genetic determinants that confer resistance and because they have the potential to laterally transfer these genetic determinants to strains of clinical importance.     

Salmonella enterica isolates from pasture‐raised poultry exhibit antimicrobial resistance and class I integrons

Aims: While considerable foodborne pathogen research has been conducted on conventionally produced broilers and turkeys, few studies have focused on free‐range (organic) or pastured poultry. The current surveillance study was designed to isolate, identify and genetically characterize Salmonella from pastured poultry farm environment and from retail samples. Methods and Results: In this study, 59 isolates were collected from two pastured poultry farms (n = 164; pens, feed, water and insect traps) and retail carcasses (n = 36) from a local natural foods store and a local processing plant. All isolates were serotyped and analysed phenotypically (antimicrobial resistance profiles) and genotypically (DNA fingerprints, plasmid profiles and integron analysis). Salmonella enterica was detected using standard microbiological methods. Salmonella Kentucky was the most prevalent serotype detected from the sampled sources (53%), followed by Salmonella Enteritidis (24%), Bareilly (10%), Mbandaka (7%), Montevideo (5%) or Newport (2%). All isolates were resistant to sulfisoxazole and novobiocin, and the majority (40/59) possessed class I integrons shown by PCR detection. Each Salmonella serotype elicited a distinct pulsed‐field gel electrophoresis fingerprint profile, and unique differences were observed among the serotypes. Conclusions: The findings of this study show that Salmonella serotypes isolated from pasture‐raised poultry exhibit antimicrobial resistance and class I integrons. Significance and Impact of the Study: This study demonstrates that despite the cessation of antibiotic usage in poultry production, antibiotic resistant Salmonella may still be recovered from the environment and poultry products.     

Occurrence and molecular characteristics of antimicrobial resistance of Escherichia coli from broilers,pigs and meat products in Thailand and Cambodia provinces

Nine hundred and forty‐one samples were collected in Sa Keao, Thailand (n = 554) and Banteay Meanchey, Cambodia (n = 387) from July 2014 to January 2015. A total of 667 Escherichia coli isolates (381 isolates from Sa Keao and 286 isolates from Banteay Meanchey) were obtained and examined for antimicrobial susceptibility, class 1 integrons, ESBL genes and horizontal transfer of resistance determinants. Prevalence of E. coli in pig and broiler carcass samples from slaughterhouses and fresh markets was 36–85% in Sa Keao and 11–69% in Banteay Meanchey. The majority of these isolates were multidrug resistant (75.3%). Class 1 integrons were common in both Thai (47%) and Cambodian (62%) isolates, of which four resistance gene cassette arrays including aadA1, dfrA1‐aadA1, dfrA12‐aadA2 and aadA2‐linF were identified. Class 1 integrons in two broiler isolates from Sa Keao (dfrA12‐aadA2) and one broiler isolate from Banteay Meanchey (dfrA1‐aadA1) were horizontally transferable. Sixteen isolates were confirmed to be ESBL‐producing strains with ESBL gene bla_CTX‐M‐15, broad spectrum β‐lactamase gene bla_TEM‐1 and the AmpC gene bla_CMY‐2 being detected. The bla_TEM‐1 gene was most prevalent and located on a conjugative plasmid.     

WQ-3810 exerts high inhibitory effect on quinolone-resistant DNA gyrase of Salmonella Typhimurium

ABSTRACT

The inhibitory effect of WQ-3810 on DNA gyrase was assayed to evaluate the potential of WQ-3810 as a candidate drug for the treatment of quinolone resistant Salmonella Typhymurium infection. The inhibitory effect of WQ-3810, ciprofloxacin and nalidixic acid was compared by accessing the drug concentration that halves the enzyme activity (IC₅₀) of purified S. Typhimurium wildtype and mutant DNA gyrase with amino acid substitution at position 83 or/and 87 in subunit A (GyrA) causing quinolone resistance. As a result, WQ-3810 reduced the enzyme activity of both wildtype and mutant DNA gyrase at a lower concentration than ciprofloxacin and nalidixic acid. Remarkably, WQ-3810 showed a higher inhibitory effect on DNA gyrase with amino acid substitutions at position 87 than with that at position 83 in GyrA. This study revealed that WQ-3810 could be an effective therapeutic agent, especially against quinolone resistant Salmonella enterica having amino acid substitution at position 87.     

Phenotypic and genetic characterization of multidrug-resistant <Emphasis Type="Italic">Salmonella</Emphasis> Infantis strains isolated from broiler chicken meats in Turkey

Twenty Salmonella Infantis strains resistant against kanamycin, tetracycline, neomycin, spectinomycin, sulphonamide, nalidixic acid and trimethoprim were selected for this study out of 103 Salmonella strains isolated from broiler samples collected from several markets in the Bolu and Ankara regions of Turkey. The resistance genes aadA1, aphA1, sul1, tet(A), dfrA5/dfrA14 and gyrA were determined for these multidrug-resistant S. Infantis strains. S. Infantis strains contained a mega plasmid with the molecular size of 206 kb. The strains were divided into three groups according to the pulsed field gel electrophoresis patterns of XbaI digested chromosomal DNA. A Ser83→Tyr83 point mutation was found in the gyrA gene of all quinolone-resistant isolates. Filter mating experiments showed that 206 kb plasmid transferred nalidixic acid resistance associated with class I integrons.     

Antibiotic-resistant Salmonella and Escherichia coli isolates with integrons and extended-spectrum beta-lactamases in surface water and sympatric black-headed gulls

Aim: To examine surface water from a pond in the northeastern part of the Czech Republic and young black‐headed gulls (Larus ridibundus) nesting on the same pond for the presence of antibiotic‐resistant Salmonella and Escherichia coli. Methods and Results: A total of 16% (n = 87) of water and 24% (n = 216) of gull samples yielded Salmonella. Salmonella Enteritidis PT8 and PT4 were the most prevalent. Antibiotic resistance was found in 12% (n = 14) of water and 28% (n = 51) of gull salmonellae. Escherichia coli were found in 83 (95%) and 213 (99%) of pond water and gull samples, respectively. Totals of 18% (n = 83) of water and 28% (n = 213) of gull E. coli isolates were resistant to antimicrobial agents tested. Class 1 integrons were found in 21% (n = 14) of water and 15% (n = 60) of gull antibiotic‐resistant E. coli isolates. Class 2 integrons and extended‐spectrum beta‐lactamase‐producing E. coli isolates (with bla_CTX‐M‐1, bla_CTX‐M‐15‐like, bla_SHV‐2 and bla_SHV‐12) were found in 13% (eight positive, n = 60 gull‐resistant E. coli isolates) and 3% (seven positive, n = 216 gull E. coli isolates) of gull isolates, respectively. Antibiotic‐resistant E. coli isolates with identical pulsed field gel electrophoresis (PFGE) patterns were found in either gulls or water, but not both. Salmonellae of the same serotype and PFGE profile were found in both gulls and water. Conclusion: A high prevalence of antibiotic‐resistant salmonellae and E. coli were found in both pond water and in sympatric black‐headed gulls. Significance and Impact of the Study: Intensive contamination of pond surface water by antibiotic‐resistant E. coli and salmonellae was documented. Black‐headed gulls were identified as important reservoirs of antibiotic‐resistant salmonellae and E. coli, including extended‐spectrum beta‐lactamase‐producing isolates.     

Occurrence and transmission of class 1 and 2 integrons among phenotypic highly ampicillin-resistant avian <Emphasis Type="Italic">Escherichia coli</Emphasis> isolates from Pakistan

Thirty four avian Escherichia coli isolates were collected from different cities of Punjab province, Pakistan during 2008–2009. Twenty five phenotypic highly ampicillin-resistant (MICs ≥ 256 μg/ml) avian E. coli strains were selected for the investigation of occurrence and transmission of class 1, 2 and 3 integrons and β-lactamase genes. Amoxicillin, sulfonamide, trimethoprim, enrofloxacin, pefloxacin and tetracycline were the most common phenotypic resistant among ampicillin-resistant avian E. coli strains. Integrons and β-lactamase were found 60 and 72% respectively. Class 1 and 2 integrons were found 52 and 8%, while class 3 integrons were not found in all strains. All class 1 positive strains had variable fragments associated with gene cassettes dfrA7, dfrA1-aadA1, aadA1, aadA22 and dfrA12-orfF-aadA2 respectively, which confer resistance to trimethoprim and streptomycin. Class 2-positive strains had similar gene cassettes array dfrA1-sat1-aadA1 conferring resistance to trimethoprim, streptothricin and spectinomicin/streptomycin. Integrons are frequently found in β-lactamase positive isolates and widely disseminate multidrug resistance genes but they do not play role in the spreading of β-lactamase genes. Class 1 integrons gene cassette aadA22 is reported for the first time in avian E. coli. Findings of this study may provide important and useful information reflecting specific antibiotic selective pressure in Punjab province, Pakistan.     

Prevalence and diversity of class 1 integrons and resistance genes in antimicrobial-resistant Escherichia coli originating from beef cattle administered subtherapeutic antimicrobials

Aims: To characterize class 1 integrons and resistance genes in tetracycline‐resistant Escherichia coli originating from beef cattle subtherapeutically administered chlortetracycline (A44), chlortetracycline and sulfamethazine (AS700), or no antimicrobials (control). Methods and Results: Tetracycline‐resistant E. coli (control, n = 111; AS700, n = 53; A44, n = 40) were studied. Class 1 integrons, inserted gene cassettes and the presence of other antimicrobial resistance genes, as well as phylogenetic analysis, were performed by PCR, restriction enzyme analysis and sequencing. Susceptibilities to 11 antimicrobials were conducted on all isolates. Prevalence of class 1 integrase was higher (P < 0·001) in isolates from AS700 (33%) and A44 (28%) steers as compared to control (7%). Most integron gene cassettes belonged to the aad or dfr families. Correlations were found between the tet(A) gene and the genetic elements sul1 (r = 0·44), aadA1 (r = 0·61), cat (r = 0·58) and intI1(r = 0·37). Both closely and distantly related isolates harboured integrons with identical gene cassette arrays. Conclusions: Subtherapeutic administration of chlorotetracycline alone or in combination with sulfamethazine may select for class 1 integrons in bovine tetracycline‐resistant E. coli isolates. Vertical spread and horizontal transfer are responsible for the dissemination of a particular type of class 1 integron, but this study could not differentiate if this phenomenon occurred within or outside of the feedlot. Tetracycline‐resistant E. coli strains with sul1 and tet(A) genes were more likely to harbour class 1 integrons. Significance and Impact of the Study: Subtherapeutic use of chlortetracycline and sulfamethazine may promote the presence of class 1 integrons in tetracycline‐resistant E. coli isolated from feedlot cattle.     

Application of variable number of tandem repeat analysis to track Salmonella enterica ssp. enterica serovar Typhimurium infection of pigs reared on three British farms through the production cycle to the abattoir

Aims: This study investigated the diversity and persistence of Salmonella strains through the pork finishing cycle, from the farm into the abattoir. Methods and Results: Isolates from four batches of finishers, from farm to abattoir, were used. Salmonella Typhimurium isolates were subjected to molecular typing using pulsed‐field gel electrophoresis and variable number of tandem repeat analysis. The results demonstrated that infection was transferred from the farm to the abattoir. Within the abattoir, infection from individual pigs contaminated the exterior of the carcass and pigs exposed to Salmonella in the lairage were infected. Conclusions: Salmonella can be introduced at various points in the pig production and slaughter process. Carcass contamination may arise from infection on farm and exposure in the lairage and abattoir environment. Pigs could be contaminated by previous batches of pigs while in lairage or during the dressing process. Salmonella infection on farms is dynamic with multiple serovars present from different sources. Significance and Impact of the Study: Molecular typing methods facilitated the tracing of Salm. Typhimurium through the production cycle and differentiated some farm‐acquired from abattoir‐acquired strains. The findings emphasize the importance of integrated control strategies along the pork food chain.     

Typhoidal Salmonella: Distinctive virulence factors and pathogenesis

Although nontyphoidal Salmonella (NTS; including Salmonella Typhimurium) mainly cause gastroenteritis, typhoidal serovars (Salmonella Typhi and Salmonella Paratyphi A) cause typhoid fever, the treatment of which is threatened by increasing drug resistance. Our understanding of S. Typhi infection in human remains poorly understood, likely due to the host restriction of typhoidal strains and the subsequent popularity of the S. Typhimurium mouse typhoid model. However, translating findings with S. Typhimurium across to S. Typhi has some limitations. Notably, S. Typhi has specific virulence factors, including typhoid toxin and Vi antigen, involved in symptom development and immune evasion, respectively. In addition to unique virulence factors, both typhoidal and NTS rely on two pathogenicity‐island encoded type III secretion systems (T3SS), the SPI‐1 and SPI‐2 T3SS, for invasion and intracellular replication. Marked differences have been observed in terms of T3SS regulation in response to bile, oxygen, and fever‐like temperatures. Moreover, approximately half of effectors found in S. Typhimurium are either absent or pseudogenes in S. Typhi, with most of the remaining exhibiting sequence variation. Typhoidal‐specific T3SS effectors have also been described. This review discusses what is known about the pathogenesis of typhoidal Salmonella with emphasis on unique behaviours and key differences when compared with S. Typhimurium.     

Genetic diversity analyses of class 1 integrons and their associated antimicrobial resistance genes in Enterobacteriaceae strains recovered from aquatic habitats in China

Aims: To characterize the molecular diversity of class 1 integrons and antibiotic resistance (AR) genes of Enterobacteriaceae strains recovered from aquatic habitats in Jinan, Shandong Province, China. Methods and Results: Six hundred and thirty‐eight antimicrobial‐resistant Enterobacteriaceae isolated from wastewater were examined for class 1 integron. Of these, 293 were positive for the class 1 integrase gene intI1; among these, 34 gene cassettes and 29 AR genes were detected. Twenty‐nine distinct gene cassette arrays were identified by restriction fragment length polymorphism (RFLP). Seven strains harboring novel gene cassette arrays were subjected to further study, in which antimicrobial susceptibility profiles were determined, and the presence of other AR genes outside of the integrons was assayed. Several of the resistance determinants were found to be transferable by conjugation or transformation. Conclusions: This study established the assessment of class 1 integron and antimicrobial resistance gene patterns among environmental Enterobacteriaceae. Also, a restriction enzyme EcoRII was employed to develop a rapid and simple method for characterizing gene cassette arrays by RFLP analysis, which facilitated further study of novel gene cassette arrays. Significance and Impact of Study: These data not only illustrated the diversity of class 1 integron gene cassettes but also provided direct evidence that integrons mobilized gene cassettes, generating new linkages of resistance genes, and they could be integrated in gene transfer units such as conjugative plasmids to contribute to the dissemination of AR genes by horizontal gene transfer (HGT) in aquatic environments.     

Class 1 and class 2 integrons and plasmid-mediated antibiotic resistance in coliforms isolated from ten rivers in northern Turkey

We aimed to determine the molecular mechanisms of antibiotic resistance in coliforms isolated from ten rivers in northern region of Turkey. A total of 183 isolates were tested for antimicrobial susceptibility by disk diffusion and agar dilution methods. Resistance to ampicillin, streptomycin, trimethoprim, tetracycline, and chloramphenicol was detected in 58%, 51.9%, 24%, 28.4%, and 12.5%, respectively. Twelve (6.5%) phylogenetically distant organisms were detected to harbor self-transmissible plasmids ranging 52 to >147 kb in sizes. Resistances to ampicillin, tetracycline, trimethoprim, streptomycin, and nalidixic acid were commonly transferable traits. Transferable nalidixic acid-resistant strains harbored qnrS gene, which was the first report of plasmid-mediated quinolone resistance in bacteria of environmental origin in Turkey. Fourteen and five coliforms harbored class 1 and class 2 integrons, respectively, and some of them were located on transferable plasmids. Sequence analyses of variable regions of the class 1 and 2 integrons harbored various gene cassettes, dfrA1, dfr2d, dfrA7, dfrA16, dfrA17, aadA1, aadA5, bla _oxA-30, and sat1. A gene cassette array, dfrA16 has been demonstrated for the first time in a Citrobacter koseri isolate. Class 1 and class 2-bearing strains were clustered in different groups by BOX-PCR fingerprinting. Rivers in the northern Turkey may act as receptacle for the multi-drug resistant enterobacteria and can serve as reservoirs of the antimicrobial resistance determinants in the environment. The actual risk to public health is the transfer of resistance genes from the environmental bacteria to human pathogens. This study was presented in part at the 2^nd World Conference on Magic Bullets, held October 3–5, 2008 in Nurnberg, Germany.     

Characterisation of integrons and antibiotic resistance genes in Danish multiresistant Salmonella enterica Typhimurium DT104

The presence and genetic content of integrons was investigated in eight Salmonella enterica Typhimurium DT104 isolates from different pig herds in Denmark. Two different integrons were identified using PCR and sequencing. Each of the integrons carried a single resistance cassette in addition to the sul1 and qacEΔ1 genes characteristic of integrons. The first integron encoded the ant (3″)-Ia gene that specified resistance to spectinomycin and streptomycin. The second contained the pse-1 β-lactamase gene. All the multiresistant strains contained both integrons. The presence of these two integrons did not account for the total phenotypic resistance of all the isolates and does not exclude the presence of other mobile DNA elements.     

Antimicrobial susceptibility profile of Acinetobacter species isolated from blood cultures in two Japanese university hospitals

Carbapenem‐resistant Acinetobacter baumannii has rapidly spread worldwide. This study investigated antibiotic susceptibility and genotypic resistance of 123 consecutive blood culture isolates of Acinetobacter species collected between 2003 and 2011 in two Japanese hospitals. The isolates were assigned to 13 species. Carbapenem resistance was detected in four isolates. Only one A. baumannii isolate had bla_OXA‐23 together with ISAba1; the remaining three isolates had IMP‐1 metallo‐β‐lactamase. Quinolone resistance was detected in five isolates that had point mutations in the quinolone resistance‐determining region. The predominance of various non‐A. baumannii species and low prevalence of carbapenem resistance among blood culture isolates of Acinetobacter species in two Japanese hospitals were confirmed.