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Objective To study the distribution and homology of foodborne-associated extended-spectrumβ-lacta-mases (ESBLs)-producing Escherichiacoli (E. coli).Methods ESBLs-producing E. coli were isolated from differ-ent food specimens in Shaoguan from 2014 to 2015,strains were typed with pulsed-field gel electrophoresis (PFGE) and BioNumerics software.Results 1 1 strains of diarrhea-causing E. coli and 29 strains of ESBLs-producing E. co-li were isolated from 347 different sources of food specimens. PFGE analysis showed that 29 strains could be divided into 21 cluster groups,group A was predominant pattern,which included 7 strains(J2,J3,J4,J7,J9,B4,S3), group B included 2 strains (J6,J8),the other strains were sporadic clones. Similarity coefficient (SC)of 3 strains (J2,J7,J9)from health practitioners was 100% ,SC of strains from drinking water and patients with diarrhea (B4) was 97. 1% ,SC of S3 strain and 4 strains (J2,J3,J7,J9 )from health practitioners were all>90. 0% . Conclusion Foodborne-associated ESBLs-producing E. coli are widely distributed in food,water,animal,and pop-ulations,and can be transmitted through food chain,surveillance should enhanced to avoid further spread.
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Objective To investigate antimicrobial resistance and ceftriaxone resistance mechanisms in clinically isolated nontyphoidal Salmonella(NTS),and provide evidence for the prevention and control of NTS infection and rational use of antimicrobial agents.Methods 108 NTS isolates were isolated from stool specimens of outpatients with acute diarrhea in the Second Hospital of Tianjin Medical University and Tianjin Medical University General Hospital from May to October of 2014,NTS were performed antimicrobial susceptibility testing;non-ceftriaxone-susceptible isolates were typed by serological,multilocus sequence (MLST),and pulsed-field gel electrophoresis (PFGE)methods,extended-spectrumβ-lactamase (ESBL)detection and AmpC genes were detection.Results Among 108 NTS isolates,mono-drug resistance rate to 11 antimicrobial agents was 49.07% (n= 53),multidrug resistance rate was17.59% . Susceptibility rates to nalidixic acid,levofloxacin,ciprofloxacin,ceftriaxone,and ertapenem were 61.11% ,66.67% ,68.52% ,97.22% ,and 100.00% respectively. Three non-ceftriaxone-susceptible NTS isolates were detected,2 were ST11 Salmonellaenterica serotype (Sa8709,Sa8771),1 was ST34 Salmonellatyphimurium serotype(Sa8763). Cluster analysis of PFGE revealed that Sa8709 was highly similar to Sa8771 strains(91 .70% ), but the similarity to Sa8763 was low(55.80% );Sa8709 strain carried CTX-M gene,Sa8771 strain carried CTX-M and TEM genes,Sa8763 strain carried OXA gene. Conclusion Clinically isolated NTS in this area are low resistant to fluoroquinolones,multidrug resistant strains carrying ESBLs have emerged.
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ObjectiveTo screen the colonization of multidrug resistant organisms (MDROs) and determine their risk factors in intensive care unit (ICU), so as to provide the basis of prophylaxis and treatment of MDROs colonization.Methods A prospective single-center study was conducted in ICU of China-Japan Friendship Hospital from June 2008 to December 2014. The nostril and anal swabs for each patient who stayed in ICU over 24 hours were collected. Each specimen was cultured and tested for drug sensitivity. Clinical findings and relative risk factors were collected. The risk factors of MDROs colonization were analyzed with univariate analysis. The independent risk factor was selected from the risk factors withP 9 days (OR = 1.766, 95%CI = 1.235 - 3.986,P = 0.021) were independent risk factors of MDROs colonization on admission to ICU.ConclusionsHigh prevalence of MDROs colonization in ICU patients was found in our hospital, and ESBL enterobacteria was the predominant bacteria. ICU acquired MDROs colonization is also worth considering, especially for MDR-AB. Identification of risk factors for MDROs colonization may help identify and screen patients with high risk, and it is also instructive in prophylaxis of MDROs colonization/infection and restriction of the use of broad spectrum antibiotics.
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Objective To evaluate the capabilities of disc diffusion and Vitek2-compact GN13 methods for testing antimicrobial susceptibility of screening ESBLs ( extended-spectrumβ-lactamase) in En-terobacteriaceae clinical isolates.Methods A total of 93 Enterobacteriaceae strains were isolated from pa-tients with intra-abdominal infections in 21 hospitals during 2011 to 2012.The in vitro minimum inhibition concentration ( MIC ) values of ampicillin-sulbactam, piperacillin-tazobactam, ertapenem, ceftazidime, ceftriaxone, cefepime, imipenem, amikacin, ciprofloxacin and levofloxacin were determined by disc diffu-sion, Vitek2-compact GN13 and broth microdilution methods, respectively.Categorical agreement ( CA ) rates of disc diffusion and Vitek2-compact GN13 methods were determined by using broth microdilution meth-od as the reference method.The genes encoding ESBLs were screened in Escherichia coli (E.coli), Kleb-siella pneumoniae (K.pneumonia), Klebsiella oxytoca (K.oxytoca) and Proteus mirabilis (P.mirabilis) strains by using PCR analysis and gene sequencing.Disc diffusion and Vitek2-compact GN13 methods were used for the phenotypic confirmatory test of ESBLs and the sensitivity, specificity, positive predictive value and negative predictive value of the two tests were evaluated.Results The CA values of disc diffusion and Vitek2-compact GN13 methods for the 10 antibiotics were all >90% as compared with broth microdilution method.The major error (ME) rate for ertapenem was 3.2%and the very major error (VME) rates for am- picillin-sulbactam, ceftazidime and cefepime tests were all 2.2% by using Vitek2-compact GN13 method. The sensitivity, specificity, positive predictive value and negative predictive value of disc diffusion and Vitek2-compact GN13 methods in the phenotypic confirmatory test of ESBLs were 96.7%(29/30), 100%(20/20), 100%(30/30) and 95%(19/20), respectively.Conclusion Both disc diffusion and Vitek2-compact GN13 methods could be used for testing the antimicrobial susceptibility and the detection of ESBLs in Enterobacteriaceae clinical isolates with the advantage of accuarcy.Attention should be paid to the posibil-lity of oaurance of ME and VME when testing ertapenem, ampicillin-sulbactam, ceftazidime and cefepime by using Vitek2-compact GN13 method.
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Objective To develop a multiplex touchdown PCR for simultaneous detection of extended-spectrum β-lactamases (ESBLs )-producing Enterobacteriaceae and methicillin-resistant Staphylococcus aureus (MRSA ). Methods Blood culture positive specimens from 102 hospitalized patients were collected between March 2013 and September 2014,four pairs of specific primers were designed based on SHV,TEM,and OXA genes of ESBLs-pro-ducing Enterobacteriaceae and MecA gene of MRSA,drug-resistant genes were amplified with single touchdown PCR and multiplex touchdown PCR, the results were compared with Kirby-Bauer disk diffusion method. Results Each single PCR amplified a specific band,four drug-resistant genes were also detected by multiplex touchdown PCR;the lower detection limits of multiplex touchdown PCR for DNA of MecA,SHV,TEM,and OXA were 4.37 ng,2.19 ng,4.53 ng,and 3.59 ng,respectively.Compared with Kirby-Bauer disk diffusion method, the overall sensitivity and specificity of multiplex touchdown PCR were 100.00% and 88.24% respectively,for ES-BLs were 100.00% and 87.23% respectively,for MRSA were both 100.00%.Conclusion A higher sensitivity and specificity multiple touchdown PCR assay has been developed,and it can be used in the rapid diagnosis and epidemi-ology investigation of bloodstream infection caused by ESBLs-producing Enterobacteriaceae and MRSA,and is help-ful for guiding antimicrobial use in clinic.
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Objective To investigate colonization of multidrug-resistant organisms (MDROs)in neonatal intensive care unit (NICU)newborns on admission.Methods From April to November 2013,293 newborns who admitted to NICU of a hospital were screened for methicillin-resistant Staphylococcus aureus (MRSA)by nasal and throat swabs and for extended-spectrumβ-lactamases (ESBLs)bacteria and vancomycin-resistant Enterococcus (VRE)by anal swabs.Results Of 293 newborns,61 were detected MDROs (20.82%).The positive rate of MDROs screening in newborns aged 3 days,and appropriate isolation measures should be taken for positive screening patients to prevent the transmission of MDROs.