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Antimicrobial Resistance and Cytotoxicity of Citrobacter spp. in Maanshan Anhui Province, China.

ABSTRACT: Objectives:Citrobacter spp. especially Citrobacter freundii, is frequently causing nosocomial infections, and increasingly becoming multi-drug resistant (MDR). In this study, we aimed to determine the genetic diversity and relationships of Citrobacter spp. from diarrheal patients and food sources, their antimicrobial resistance profiles and in vitro virulence properties. Methods: Sixty two Citrobacter isolates, including 13 C. freundii, 41 C. youngae and eight C. braakii isolates, were obtained from human diarrheal patients and food sources. Multilocus Sequence Typing (MLST) of seven housekeeping genes and antimicrobial susceptibility testing using the broth microdilution method according to CLSI recommendations were carried out. Adhesion and cytotoxicity to HEp-2 cells were performed. PCR and sequencing were used to identify blaCTX-M, blaSHV, blaTEM and qnr genes. Results: The 62 isolates were divided into 53 sequence types (STs) with all STs being novel, displaying high genetic diversity. ST39 was a predominant ST shared by 5 C. youngae strains isolated from four foods and a diarrheal patient. All isolates were resistant to cefoxitin, and sensitive to imipenem, meropenem and amikacin. The majority of Citrobacter isolates (61.3%) were MDR of three or more antibiotics out of the 22 antibiotics tested. Two C. freundii isolates each carried the blaTEM-1 gene and a variant of qnrB77. Three Citrobacter isolates each carried qnrS1 and aac(6')-Ib-cr genes. Seven isolates that showed strong cytotoxicity to HEp-2 cells were MDR. Conclusions:Citrobacter spp. from human and food sources are diverse with variation in virulence properties and antibiotic resistance profiles. Food may be an important source of Citrobacter species in transmission to humans. C. freundii and C. youngae are potential foodborne pathogens.

SUBMITTER: Liu L

PROVIDER: S-EPMC5518651 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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Antimicrobial Resistance and Cytotoxicity of Citrobacter spp. in Maanshan Anhui Province, China.

Liu Liyun L Lan Ruiting R Liu Liqin L Wang Yonglu Y Zhang Yushi Y Wang Yiting Y Xu Jianguo J

Frontiers in microbiology 20170720

Objectives:Citrobacter spp. especially Citrobacter freundii, is frequently causing nosocomial infections, and increasingly becoming multi-drug resistant (MDR). In this study, we aimed to determine the genetic diversity and relationships of Citrobacter spp. from diarrheal patients and food sources, their antimicrobial resistance profiles and in vitro virulence properties. Methods: Sixty two Citrobacter isolates, including 13 C. freundii, 41 ...[more]

PMID: 28775715

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Project description:BackgroundShigella spp., facultative anaerobic bacilli of the family Enterobacteriaceae, are one of the most common causes of diarrheal diseases in human worldwide which have become a significant public health burden. So, we aimed to analyze the antimicrobial phenotypes and to elucidate the molecular mechanisms underlying resistance to cephalosporins and fluoroquinolones in Shigella isolates from patients with diarrhea in Shanxi Province.ResultsDuring 2006-2016, we isolated a total of 474 Shigella strains (including 337 S. flexneri and 137 S. sonnei). The isolates showed high rates of resistance to traditional antimicrobials, and 26, 18.1 and 3.0% of them exhibited resistance to cephalosporins, fluoroquinolones and co-resistance to cephalosporins and fluoroquinolones, respectively. Notably, 91.1% of these isolates, including 22 isolates that showed an ACTSuT profile, exhibited multidrug resistance (MDR). The resistance rates to cephalosporins in S. sonnei isolates were higher than those in S. flexneri. Conversely, the resistance rates to fluoroquinolones were considerably higher in S. flexneri isolates. Among the 123 cephalosporins-resistant isolates, the most common extended-spectrum beta-lactamase gene was blaTEM-1, followed by blaCTX-M, blaOXA-1, and blaSHV-12. Six subtypes of blaCTX-M were identified, blaCTX-M-14 (n = 36) and blaCTX-M-55 (n = 26) were found to be dominant. Of all the 86 isolates with resistance to fluoroquinolones and having at least one mutation (Ser83Leu, His211Tyr, or Asp87Gly) in the the quinolone resistance-determining regions of gyrA, 79 also had mutation of parC (Ser80Ile), whereas 7 contained plasmid-mediated quinolone resistance genes including qnrA, qnrB, qnrS, and aac(60)-Ib-cr. Furthermore, pulsed-field gel electrophoresis analysis (PFGE) showed a considerable genetic diversity in S. flexneri isolates. However, the S. sonnei isolates had a high genetic similarity.ConclusionsCoexistence of diverse resistance genes causing the emergence and transmission of MDR might render the treatment of shigellosis difficult. Therefore, continuous surveillance might be needed to understand the actual disease burden and provide guidance for shigellosis.

Project description:BackgroundAnhui Province in China is facing a severe HIV epidemic with an increasing number of newly diagnosed cases.MethodsIn this study, HIV genetic characteristics in the province were investigated. Newly reported HIV-positive individuals from 15 districts of Anhui Province were enrolled and interviewed. Total viral RNA was extracted from plasma isolated from blood samples. We amplified and sequenced an HIV pol fragment of the 1062 bp. The sequences were used for determination of HIV subtypes and the presence of drug resistance mutations. Transmission networks were constructed to explore possible relationships. And all of assembled partial pol genes were submitted to the Stanford HIV Drug Resistance Database website to find the transmitted drug resistance.ResultsPartial pol gene sequences were obtained from 486 cases. The results showed that MSM was the most dominant transmission route (253, 52.06%), followed by heterosexual transmission (210, 43.21%) and blood-borne transmission (1, 0.21%). Many subtypes were identified, including CRF01_AE (226, 46.50%), CRF07_BC (151, 31.07%), subtype B (28, 5.76%), CRF08_BC (20, 4.12%), CRF55_01B (15, 3.09%), CRF68_01B (7, 1.44%), CRF67_01B (3, 0.62%), CRF57_BC (2, 0.41%), CRF59_01B (2, 0.41%), CRF79_0107 (2, 0.41%), subtype C (2, 0.41%), CRF64_BC (1, 0.21%), and circulating recombinant forms (URFs) (27, 5.55%). Four transmission subnetworks containing high transmission risk individuals (with degree ≥4) were identified based on CRF01_AE and CRF07_BC sequences, including two CRF01_AE transmission subnetworks constituted by elderly people with average ages of 67.9 and 61.5 years. Infection occurred most likely through heterosexual transmission, while the other two CRF07_BC transmission subnetworks consist mainly of MSMs with average ages of 31.73 and 34.15. The level of HIV-transmitted drug resistance is 3.09%.ConclusionsThe simultaneous spread of multiple HIV subtypes in Anhui province underscores that close surveillance of the local HIV epidemic is necessary. Furthermore, the elderly people were frequently involved, arguing for behaviour intervention in this specific population besides the MSM risk group.

Project description:Shigella represents one of the major diarrhea-inducing pathogens threatening public health, but its prevalence and antimicrobial resistance profile in Xinjiang Uygur Autonomous region, China, remains unclear. We conducted comprehensive investigation of Shigella serotype distribution and antimicrobial resistance pattern in Xinjiang, identifying 458 Shigella isolates between 2008 to 2014. Shigella flexneri was identified as predominant species, and several S. flexneri serotypes were isolated, including atypical serotypes 1c, 2c, and 4s. Dominant S. flexneri serotypes were 2a, 1b, 2b, and Xv, different from those generally dominant in China. A hybrid serotype pattern was observed, which included the major Chinese serotypes (2a, Xv) and those predominant in Pakistan (1b, 2b). Shigella sonnei was shown to have a lower frequency compared with that generally observed in China, but an increasing trend of infections associated with this pathogen was observed. Furthermore, a high frequency of drug resistance and different Shigella antimicrobial resistance patterns were demonstrated as well, including very severe resistance phenotypes, such as multidrug resistance and resistance to frontline antibiotics. Seventy-five cephalosporin-resistant Shigella isolates were frequently identified with the resistance determinants that can undergo horizontal transfer, such as blaOXA, blaTEM, blaCTX-M, and integrons, facilitating the development of cephalosporin resistance among Shigella subtypes. Additionally, genetic analyses demonstrated that all 86 quinolone-resistant S. flexneri isolates possess 3-4 mutation sites in quinolone resistance-determining regions, primarily contributing to their resistance to quinolone. However, S. sonnei isolates were not shown to be quinolone resistant. Co-resistance to cephalosporins and quinolones was detected in 17 S. flexneri isolates, and these isolates were additionally multidrug resistant and carried ?-lactamase genes and quinolone-resistance determinants. As is demonstrated in this study, dominant serotypes of Shigella were distributed in unique trend with dangerous drug resistance patterns. Novel strategies are urgently required to prevent the development of drug resistance among diarrhea-inducing pathogens.

Dataset Information

Antimicrobial Resistance and Cytotoxicity of Citrobacter spp. in Maanshan Anhui Province, China.

Publications

Antimicrobial Resistance and Cytotoxicity of <i>Citrobacter</i> spp. in Maanshan Anhui Province, China.

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