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Antimicrobial resistance is a serious problem for anti-infective treatment. Molecular technology can quickly, sensitively and accurately detect the mechanism of drug resistance of bacteria, improving the efficacy of anti-infection treatment and the level of infection control. The construction of quality assurance system is a guarantee for the effective application of molecular diagnostic technology in the detection of bacterial resistance. However, due to the complex mechanism of drug resistance, coupled with genetic mutations and other factors, there are problems such as false negatives, false positives, and inconsistency between mechanisms and phenotypes, there are certain restrictions on the application of molecular detection technology. With the development of molecular technology and deepening of people′s understanding of the drug resistance mechanism, the application of molecular diagnostic technology in the detection of bacterial resistance will be more widespread.
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Objective To evaluate the performance of Xpert C. difficile multiplex real-time PCR assay for diagnosis of Clostridium difficile infections in Chinese hospital settings. Methods This study was performed in Huashan Hospital, Ruijin Hospital, Beijing Hospital, Nanfang Hospital and Sir Run Run Shaw Hospital using a standard study protocol. Unique unformed stools from patients with acute hospital-acquired diarrhea were simultaneously analyzed by toxigenic anaerobic cultures and the Xpert C. difficile assay. All specimens displaying discordant results between the Xpert assay and toxigenic culture were sent for Sanger tcdB gene sequencing. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), total concordance rate, and 95％ confidence interval (CI) were calculated before and after resolution of discordant results using SAS 9.3. Results A total of 745 stool specimens were collected and 46 were excluded due to failure of C. difficile recovery. The remaining 699 specimens were included. Compared to the results of toxigenic culture, the sensitivity, specificity, PPV, and NPV of Xpert C. difficile assay were 94.1％ (144/153)(95％CI:89.1％-97.3％), 93.2％ (509/546)(95％CI:96.7％-99.2％), 79.6％ (144/181)(95％CI:72.9％-85.2％)and 98.3％ (509 / 518) (95％CI: 96.7％-99.2％), respectively. Both methods had a Kappa of 0.819. Xpert C. difficile assay showed sensitivity of 98.4％(62/63) (95％ CI: 90.3％-99.9％) and specificity of 93.2％(509/546) (95％ CI: 90.8％-95.2％) for toxin A-negative toxin B-positive strains. After the discordant results resolved by tcdB gene sequencing, PCR assay provided better performance with high sensitivity, specificity, positive predictive value, and negative predictive value [98.8％ (171 / 173), 98.1％ (516 / 526), 94.5％ (171/181) and 99.6％ (516/518), respectively]. Conclusions Compared to the results of toxigenic culture, the sensitivity, specificity and NPV of Xpert C. difficile assay were 94.1％ (144/153) and 93.2％(509/546), respectively. With the results available within 1 h, Xpert C. difficile assay provides prompt and precise laboratory diagnosis in Chinese clinical settings.
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Objective To investigate the antimicrobial resistance profile of the clinical isolates collected from selected hospitals across China. Methods Twenty-nine general hospitals and five children's hospitals were involved in this program. Antimicrobial susceptibility testing was carried out according to a unified protocol using Kirby-Bauer method or automated systems. Results were interpreted according to CLSI 2017 breakpoints. Results A total of 190 610 clinical isolates were collected from January to December 2017, of which gram negative organisms accounted for 70.8％ (134 951/190 610) and gram positive cocci 29.2％ (55 649/190 610). The prevalence of methicillin-resistant strains was 35.3％ in S. aureus (MRSA) and 80.3％ in coagulase negative Staphylococcus (MRCNS) on average. MR strains showed much higher resistance rates to most of the other antimicrobial agents than MS strains. However, 91.6％ of MRSA strains were still susceptible to trimethoprim-sulfamethoxazole, while 86.2％ of MRCNS strains were susceptible to rifampin. No staphylococcal strains were found resistant to vancomycin. E. faecalis strains showed much lower resistance rates to most of the drugs tested (except chloramphenicol) than E. faecium. Vancomycin-resistant Enterococcus (VRE) was identified in both E. faecalis and E. faecium. The identified VRE strains were mainly vanA, vanB or vanM type based on phenotype or genotype. The proportion of PSSP or PRSP strains in the non-meningitis S.pneumoniae strains isolated from children decreased but the proportion of PISP strains increased when compared to the data of 2016. Enterobacteriaceae strains were still highly susceptible to carbapenems. Overall, less than 10％ of these strains (excluding Klebsiella spp.) were resistant to carbapenems. The prevalence of imipenem-resistant K. pneumoniae increased from 3.0％ in 2005 to 20.9％ in 2017, and meropenem-resistant K. pneumoniae increased from 2.9％ in 2005 to 24.0％ in 2017, more than 8-fold increase. About 66.7％ and 69.3％ of Acinetobacter (A. baumannii accounts for 91.5％) strains were resistant to imipenem and meropenem, respectively. Compared with the data of year 2016, P. aeruginosa strains showed decreasing resistance rate to carbapenems. Conclusions Bacterial resistance is still on the rise. It is necessary to strengthen hospital infection control and stewardship of antimicrobial agents. The communication between laboratorians and clinicians should be further improved in addition to surveillance of bacterial resistance.
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Objective To evaluate the changing pattern of antibiotic resistance inKlebsiella strains isolated from the patients in 19 hospitals across China based on the data from CHINET Antimicrobial Resistance Surveillance Program during the period from 2005 through 2014.Methods Kirby-Bauer disk diffusion and automated susceptibility testing methods were used to test the susceptibility ofKlebsiella isolates to the commonly used antibiotics. The results were interpreted according to the criteria of the Clinical and Laboratory Standards Institute (CLSI) Performance Standards for Antimicrobial Susceptibility Testing (CLSI-2014).Results A total of 61 406Klebsiella strains were identified between 2005 and 2014, includingK. pneumoniae (56 281 strains), K. oxytoca(4 779),Klebsiella pneumoniae subsp.Ozaenae (300) and otherKlebsiella species (46). Most (89.0%, 54 664/61 406) of theKlebsiella strains were isolated from inpatients, and 60.0% (36 835/61 406) were from respiratory tract speciems. About 16.7% (10 248/61 406) of the strains were isolated from pediatric patients aged 0-17 years and 83.3% (51 158/61 406) from adult patients. The prevalence ofKlebsiella spp. increased with time from 10.1% in 2005 to 14.3% in 2014. Based on the surveillance data during the 10-year period, we found a marked increase of resistance to imipenem (2.9% to 10.5%) and meropenem (2.8% to 13.4%) inKlebsiella spp. The prevalence of ESBLs-producing isolates inK. pneumoniae andK. oxytoca decreased from 39.0% in 2005 to 30.1% in 2014. The resistance to amikacin, ceftazidime, ciprolfoxacin, pipracillin-tazobactam and cefoperazone-sulbactam was on decline. The resistance rate to cefotaxime remained high about 49.5%. Carbapenem resistantance was identiifed in 5 796 (9.4%) of the isolates, including 5 492 strains ofK. pneumoniae and 280 strains ofK. oxytoca. Overall, 4 740 (7.8%) strains were identiifed as extensively-drug resistant (XDR), including 4 520 strains ofK. pneumoniae and 202 strains ofK. oxytoca. The carbapenem-resistant strains showed high (>60%) resistance rate to majority of the antimicrobial agents tested, but relatively low resistance to tigecycline (16.8%), amikacin (54.4%), and trimethoprim-sulfamethoxazole (55.5%).Conclusions During the 10-year period from 2005 through 2014, carbapenem resistance amongKlebsiella isolates has increased dramatically in the hospitals across China. The level of resistance to other antibiotics remains stable.
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Objective To investigate the distribution and antibiotic resistance proifle of clinicalEnterobacter isolates using the data from CHINET during the period from 2005 through 2014.Methods A total of 20 558 clinical strains ofEnterobacter spp. were collected from 2005 to 2014 in CHINET Antimicrobial Resistance Surveillance Program. Antimicrobial susceptibility testing was performed with Kirby-Bauer or minimum inhibitory concentration method. The results were analyzed according to CLSI 2014 breakpoints.ResultsEnterobacter cloacae andEnterobacter aerogenes accounted for 71.1% (14 617/20558) and 20.1% (4 129/20 558) of all theEnterobacterisolates, respectively. The proportion ofEnterobacter spp. increased with time from 3.5% in 2005 to 4.3% in 2014. The main source of the isolates was respiratory tract, accounting for 55.2% (11 358/20 558). More than 90% of theEnterobacterisolates were resistant to cefazolin and cefoxitin, but less than 30% of the strains were resistant to cefepime, piperacillin-tazobactam, cefoperazone-sulbactam, amikacin, gentamicin, ciprolfoxacin, meropenem, imipenem and ertapenem. TheEnterobacterisolates showed a trend of declining resistance to most antibiotics except ertapenem and meropenem. The resistance proifle ofEnterobacterisolates varied with departments where they were isolated. The strains from ICU and Department of Surgery were relatively more resistant to antibiotics. The prevalence of multi-drug resistant (MDR) strains was decreasing, but the prevalence of carbapenem-resistantEnterobacter (CRE, resistant to any of imipenem, meropenem or ertapenem) was increasing. The MDR and CRE strains were primarily isolated from ICU and Department of Surgery. At least 30% of the MDREnterobacter strains were resistant to any of the antimicrobial agents tested except meropenem, imipenem and ertapenem and at least 35% of the CRE strains were resistant to any of the antimicrobial agents tested except amikacin and ciprolfoxacin.Conclusions TheEnterobacter isolates in CHINET Antimicrobial Resistance Surveillance Program showed decreasing resistance to most of the antimicrobial agents tested since 2011, but the prevalence of CRE strains increased progressively. Effective measures should be carried out to prevent the spread of CRE strains in hospitals.
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Objective To understand the changing resistance proifle ofProteus,Serratia,Citrobacter,Morganella andProvidencia in hospitals across China according to the data from CHINET Antimicrobial Resistance Surveillance Program 2005-2014.Methods Antimicrobial susceptibility was tested by using Kirby-Bauer method or automatic minimum inhibitory concentration determination according to a uniifed protocol.Results A total of 21 663 clinical isolates were collected from January 2005 to December 2014. The proportion ofProteus andSerratia isolates increased with time from 1.41% in 2005 to 2.09% in 2014, and from 0.99% in 2005 to 1.28% in 2014 among all the isolates. No change was found for the proportion ofCitrobacter,Morganella, orProvidencia. Less than 10% of theProteus isolates were resistant to cefoperazone-sulbactam, piperacillin-tazobactam, ceftazidime, cefoxitin, amikacin and tigecycline. Less than 10% of theSerratia isolates were resistant to cefoperazone-sulbactam, piperacillin-tazobactam, amikacin and tigecycline. Less than 20% of theCitrobacter isolates were resistant to cefoperazone-sulbactam, piperacillin-tazobactam, cefepime, amikacin and tigecycline. Less than 10% of theMorganella isolates were resistant to cefoperazone-sulbactam, piperacillin-tazobactam, cefepime, amikacin and tigecycline. Less than 20% of theProvidencia isolates were resistant to cefoperazone-sulbactam, piperacillin-tazobactam, cefepime, cefoxitin and tigecycline.Conclusions The antibiotic resistance ofProteus,Serratia, Citrobacter,Morganella andProvidencia isolates in hospitals across China is growing during the period from 2005 to 2014. Strengthening infection control and rational antibiotic use are effective to slow the growth of drug resistance.
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Objective To investigate the distribution and changing resistance proifle ofSalmonella isolates in hospitals across China during the period from January 2005 to December 2014.Methods Seventeen general hospitals and two children’s hospitals were involved in this program. Antimicrobial susceptibility testing was carried out by means of a unified protocol using Kirby-Bauer method or MIC determination. The results were analyzed according to CLSI 2014 breakpoints.Results The proportion ofSalmonella isolates increased with time from 0.2% in 2005 to 0.7% in 2014. A total of 3 478Salmonella strains were collected from 19 hospitals. The proportion ofSalmonella typhimurium andSalmonella enteritidis was 27.4% and 24.4%, respectively. During the 10-year period, theSalmonella strains showed highest resistance rate to ampicillin (33.3%-64.8%), but low resistance to cefoperazone-sulbactam (0-5.3%) and ciprofloxacin (2.4%-14.3%).S. typhimurium showed higher resistance rate thanS. typhi,S. paratyphi andS. enteritidis. About 76.8% and 50.5% ofS. typhimurium were resistant to ampicillin and trimethoprim-sulfamethoxazole. The average prevalence of multi-drug resistantSalmonellawas 3.9% in the ten-year period, the highest (7.5%) was in 2005, the lowest (1.5%) in 2013.Conclusions During the period from 2004 to 2015, majority of theSalmonella isolates in hospitals across China wasS. typhimurium andS. enteritidis. Ampicillin and trimethoprim-sulfamethoxazole are no longer appropriate for empirical treatment ofS. typhimurium infection due to high resistance rate.Salmonella isolates are relatively more susceptible to third-generation cephalosporins and quinolones. Ongoing monitoring is necessary to identify multi-drug resistant strains ofSalmonella.
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Objective To analyze the resistance proifle of bacterial strains isolated from geriatric patients in 17 hospitals across China from 2005 to 2014.Methods A total of 17 representative general hospitals were involved in this program. Bacterial susceptibility testing was carried out by means of a uniifed protocol using Kirby-Bauer method and MIC determination. The results were analyzed according to CLSI 2014 breakpoints.Results The proportion of the strains isolated from geriatric patients among all the clinical isolates increased with time from 30.0% in 2005 to 32.7% in 2014. A total of 159 888 clinical isolates were collected from geriatric patient during the period from 2005 to 2014, about 33.1% of the whole patient population. Gram negative organisms and gram positive cocci accounted for 77.1% (123 229/159 888) and 22.9% (36 659/159 888), respectively. Majority (92.8%, 148 376/159 888) of the isolates were from inpatients and more than half (55.2%, 88 201/159 888) of the isolates were from sputum or other respiratory tract specimens. Methicillin-resistant strains inS. aureus (MRSA) and coagulase negativeStaphylococcus (MRCNS) accounted for an average of 67.1% and 75.9%, respectively. The resistance rates of methicillin-resistant strains to β-lactams and other antimicrobial agents were much higher than those of methicillin-susceptible strains. No staphylococcal strains were found resistant to vancomycin, teicoplanin or linezolid. Some strains ofE. faecalis (0.4%) andE. faecium (4.6%) were resistant to vancomycin, which was higher than average national level (0.3%, 3.2%). Vancomycin-resistant strains ofE. faecalisandE. faecium were mainly VanA type and VanB type based on their phenotype. The prevalence of penicillin-susceptibleS. pneumoniae strains was 78.2%, slightly lower than the 95.0% in Chinese adults in year 2014. The prevalence of ESBLs-producing strains was 67.5% inE. coli, 40.4% inKlebsiella (K. pneumoniae andK. oxytoca) and 34.3% inProteus mirabilis isolates on average. The strains ofEnterobacteriaceae were still highly susceptible to carbapenems (<10% resistant), followed by amikacin and the beta-lactam and beta-lactamase inhibitor combinations. Overall, 35.9% and 33.0% of theP. aeruginosa strains were resistant to imipenem and meropenem. More than 50% of theA. baumannii strains were resistant to imipenem and meropenem. The prevalence of extensively drug-resistant (XDR)P. aeruginosa (4.0%-1.8%) was higher than the average national level (2.1%-1.6%). The prevalence of XDR A. baumannii (19.2%-15.5%) and XDREnterobacteriaceae (0.1%-1.0%) was lower than the average national level (21.4%-19.7% and 0.3%-3.2%).Conclusions The proportion of clinical isolates from geriatric patients is different from average national level at the same period. The isolates from geriatric patients are more likely from inpatients, respiratory tract specimens and more likely non-fermentative gram-negative bacilli compared to average national level. The proportion of fastidious bacteria andEnterobacteriaceae species is generally lower than average national level. MRSA, VRE, ESBLs-producing strains and XDRP. aeruginosa are more prevalent in geriatric patients than in general Chinese patient population. This study suggests that surveillance of antimicrobial resistance for the clinical isolates from geriatric patients is very important for rational antimicrobial therapy.
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Objective Toinvestigateantimicrobialresistanceamonggram-positivecocciinChinain 2013.Methods Retrospectivestudy.FromJune2013toDecember2013,1663consecutiveandnon-repetitive gram-positive cocci were collected from 15 teaching hospitals. The minimal inhibitory concentration ( MIC) of antibacterial agents was determined by agar dilution method. A retrospective study was conducted on rates of resistance to antimicrobial agents. The prevalence of penicillin-resistant Streptococcus pneumoniae ( PRSP) between children and adult patients and the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) between elder group and younger adult patients were compared using chi-square test. Results The prevalence of PRSP in children below 3 years old ( 72. 9%, 51/70 ) was higher than adult patients (55. 2%, 106/192) (χ2 =6. 653,P<0. 05). About 94. 9%(261/275) and (92. 7%,255/275) of S. pneumonia were resistant to erythromycin and clindamycin. All S. pneumoniae strains were susceptible to teicoplanin, vancomycin, linezolid, tigecycline and daptomycin. Penicillin still showed very high activity against Streptococcus spp. β-Hemolytic group. More than 60% of Streptococcus spp.β-Hemolytic group were resistant to erythromycin, clindamycin and tetracyclines. The prevalence of MRSA and methicillin-resistant coagulase-negative Staphylococci(MRCoNS) was 39. 7%(229/576) and 80. 6%(224/278), respectively. The MRSA prevalence ranged from 24. 2% to 70. 0% in different regions. About 52. 6%( 100/190 ) of Staphylococcus aureus from respiratory tract specimens, 38. 5%(40/104)of Staphylococcus aureus from blood samples, and 29. 7%(58/195) of Staphylococcus aureus from wound and pus were resistant to methicillin. The prevalence of MRSA in elder group ( 48. 6%, 84/173 ) was higher than that in younger adult patients (35. 7%, 144/403)(χ2 =8. 322,P <0. 05). The susceptibility rates of MRSA to chloramphenicol and trimethoprim/sulfamethoxazole were 86. 4% ( 244/228 ) and 94. 7% ( 237/228 ) , respectively. Susceptibility rates to gentamycin, erythromycin, clindamycin, tetracyclines, rifampicin and quinolones were ranged from 15. 8% to 59. 6%. All Staphylococci isolates were susceptible to teicoplanin, vancomycin, linezolid, daptomycin and tigecycline. All Enterococcus isolates were susceptible to daptomycin and tigecycline. All E. faecalis ( 158/158 ) and 96. 4% ( 133/138 ) of E. faecium were susceptible to teicoplanin. About 98. 0% ( 150/153 ) of E. faecalis and 97. 1% ( 145/138 ) of E. faecium were susceptible to linezoild. About 45. 8% (70/153) of E. faecalis and 60. 9% (84/138) of E. faecium were resistant to gentamycin with a high concentration. The susceptibility of E. faecalis to all the antibiotics tested exceptchloramphenicolandtetracyclinewashigherthanthatofE.faecium.Conclusions Basedon different age groups and regions, the resistance rates of Gram-positive cocci are different. Teicoplanin, vancomycin, tigecycline, daptomycin, linezolid and tedizolid showed very high activity against Gram-positive cocci. (Chin J Lab Med,2015,38:373-381)
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Objective To assess the risk factors of multidrug-resistant organism(MDRO)healthcare-associated pneumonia(HCAP).Methods The case-control study was conducted in patients admitted to 22 hospitals in 4 cities between April 1 ,2013 and December 31 ,2013,patients with HCAP caused by MDRO (MRSA,MDRPA,MDRAB, ESBL KP,ESBL E.coli)(drug-resistant group )and drug-sensitive organisms (MSSA,PA,AB,KP,E.coli)(drug-sensitive group )were surveyed .Univariate and multivariate statistical analysis methods were used to evaluate the risk factors for MDRO HCAP.The prognosis,cost and length of hospital stay between drug-resistant group and drug-sensitive group were compared .Results A total of 1 656 patients were included in the study ,including 43 pa-tients (2.60%)with mixed infection caused by both drug-resistant and drug-sensitive organisms ;there were 927 ca-ses (55.98%)in drug-resistant group and 772 cases(46.62%)in drug-sensitive group .Logistic regression model re-vealed that admission to ICUs (OR 95%CI :1 .55[1 .14-2.11]),mechanical ventilation (OR 95%CI :1 .45[1 .15-1 .84]),arteriovenous catheterization (OR 95%CI :1 .29 [1 .02 - 1 .63 ]),fiberbronchoscopy (OR 95%CI :1 .46 [1 .02-2.09]),antimicrobial use(OR 95%CI :1 .63[1 .20-2.22]),chronic lung diseases (OR 95%CI :1 .54[1 .13-2.10]),and chronic cardiovascular and cerebrovascular diseases (OR 95%CI :1 .42[1 .15-1 .74])were independ-ent risk factors for MDRO HCAP .Compared with drug-sensitive group ,drug-resistant group prolonged length of hospital stay by an average of 5.89 days,increased hospitalization and antimicrobial expense by ￥40 739.30 and￥2 805.80 respectively;prognoses was worse,risk factor was 1 .66-fold of drug-sensitive group(OR 95%CI :1 .16-2.35).Conclusion Admission to ICUs,invasive operations,antimicrobial use,chronic lung diseases and chronic cardiovascular and cerebrovascular diseases can increase the risk of MDRO HCAP .
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Objective To investigate the susceptibility and resistance of clinical isolates collected from hospitals in several regions of China . Methods Fourteen general hospitals and two children ’ s hospitals were involved in this program . Antimicrobial susceptibility testing was carried out according to a unified protocol using Kirby-Bauer method or automated Systems .Results were analyzed according to CLSI 2013 breakpoints .Results A total of 84 572 clinical isolates were collected from January to December 2013 ,of which gram negative organisms and gram positive cocci accounted for 73 .0% and 27 .0%respectively .Methicillin-resistant strains in S .aureus (MRSA) and coagulase negative Staphylococcus (MRCNS) accounted for an average of 45 .2% and 73 .5% respectively .The resistance rates of methicillin-resistant strains to β-lactams and other antimicrobial agents were much higher than those of methicillin-susceptible strains .However ,92 .2% of MRSA strains were still susceptible to trimethoprim-sulfamethoxazole while 87 .4% of MRCNS strains were susceptible to rifampin . No staphylococcal strains were found resistant to vancomycin ,teicoplanin or linezolid .In Enterococcus spp .,the resistance rates of E . f aecalis strains to most tested drugs (except chloramphenicol) were much lower than those of E . f aecium .Some strains of both species were resistant to vancomycin .Vancomycin-resistant strains of E . f aecalis and E . f aecium were mainly VanA type based on their phenotype .Regarding non-meningitis S . pneumoniae strains ,the prevalence of penicillin-susceptible S . pneumoniae and penicillin-intermediate S . pneumoniae strains isolated from both adults and children were lower than those isolated in 2012 ,but the prevalence of penicillin-resistant S .pneumoniae strains increased .The prevalence of ESBLs producing strains was 54 .0% in E .coli ,31 .8% in Klebsiella spp .(K .pneumoniae and K .oxytoca) and 16 .5% in Proteus mirabilis isolates on average . ESBLs-producing Enterobacteriaceae strains were more resistant than non-ESBLs-producing strains in terms of antibiotic resistance rates .The strains of Enterobacteriaceae were still highly susceptible to carbapenems .Overall less than 7 .0% of these strains were resistant to carbapenems .About 62 .8% and 59 .4% of Acinetobacter spp .(A .baumannii accounts for 89 .2% ) strains were resistant to imipenem and meropenem ,respectively .Compared with the data of year 2012 , extensively-drug resistant strains in K . pneumoniae and A . baumannii decreased .Conclusions The antibiotic resistance of clinical bacterial isolates is growing in 2013 .The disseminated multi-drug or pan-drug resistant strains in a special region poses a serious threat to clinical practice and implies the importance of strengthening infection control .
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Objective To investigate the distribution and susceptibility of carbapenem-resistant Enterobacteriaceae (CRE) isolates in 2012 from CHINET surveillance .Methods Antimicrobial susceptibility testing was carried out according to a unified protocol using Kirby-Bauer method or automated Systems .Results were analyzed according to the breakpoints of CLSI 2012 M100-S22 .Results A total of 1 499 CRE isolates were collected from January to December 2012 ,of which K lebsiella spp .,Enterobacter spp .and E .coli accounted for 63 .5% ,15 .1% and 13 .7% ,respectively .Of the 1 499 isolates , 48 .2% and 29 .3% were from respiratory tract and ICU , respectively . The results of antimicrobial susceptibility testing showed that the resistance rate of CRE isolates to most antimicrobial agents was 70 .0%-100% except amikacin (46 .9% ) and trimethoprim-sulfamethoxazole (49 .8% ) .CRE isolates from adults were more resistant to ciprofloxacin ,aminoglycosides and trimethoprim-sulfamethoxazole than those from children .Conclusions The antibiotic resistance of CRE isolates is very high . The spread of CRE strains in a specific region such as ICU and neurosurgery ward poses a serious threat to clinical practice and implies the importance of strengthening infection control .
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Objective To investigate the distribution and antibiotic resistance of clinical Enterobacter isolates .Methods A total of 3 031 clinical strains of Enterobacter were collected from 15 hospitals from January 1 through December 31 , 2012 . Antimicrobial susceptibility testing was performed with Kirby-Bauer or minimum inhibitory concentration method .The results were analyzed according to CLSI 2012 breakpoints .Results Enterobacter cloacae and Enterobacter aerogenes accounted for 73 .0% (2 212/3 031) and 23 .9% (725/3 031) of all the Enterobacter strains .The isolates of other Enterobacter species accounted for 3 .1% (94/3 031 ) . The main source of the isolates was respiratory tract specimen , accounting for 53 .2% (1 612/3 031) .Most (> 89% ) of the Enterobacter strains were resistant to cefazolin and cefoxitin . Generally ,54 .4% ,47 .5% and 34 .3% of the strains were resistant to cefuroxime ,cefotaxime and cefazidime ,respectively . About 6 .6% to 26 .3% of the strains were resistant to amikacin ,gentamicin ,piperacillin-tazobactam ,cefepime ,cefoperazone-sulbactam ,ciprofloxacin and trimethoprim-sulfamethoxazole .Imipenem ,meropenem and ertapenem showed the highest activity , to which only 3 .5% ,3 .7% and 10 .3% of the strains were resistant ,respectively .About 8 .9% (269/3 031) of the strains were resistant to at least imipenem ,meropenem or ertapenem .Four Enterobacter strains were extensive-drug resistant (XDR) .Conclusions The prevalence of antibiotic resistance in Enterobacter isolates decreased slightly in 2012 compared to the data in 2011 ,but the situation is still very serious .We should continue to take effective measures to control the resistant strains .
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Objective To investigate the antimicrobial resistance in the A cinetobacter baumannii strains in different parts of China during 2012 .Methods A total of 8 739 clinical isolates of Acinetobacter were collected from 13 general hospitals and two children’s hospitals ,of which most were A . baumannii (89 .6% , 7 827/8 739 ) . Antimicrobial susceptibility testing was carried out by means of Kirby-Bauer method according to the unified protocol . The susceptibility testing data were analyzed by WHONET 5 .6 software according to CLSI 2013 breakpoints .Results Majority (85 .4% ) of the Acinetobacter strains were isolated from inpatients .The remaining 14 .6% were from outpatients and emergency room patients .Of the 7 827 strains of A .baumannii , 10 .9% ,35 .2% ,35 .7% and 43 .4% were resistant to tigecycline ,minocycline ,cefoperazone-sulbactam and amikacin , respectively .The percentage of A .baumannii resistant to imipenem and meropenem was 63 .5% and 68 .2% ,respectively . The antimicrobial resistant pattern varied in different hospitals . The resistance of A . baumannii varied between different clinical departments .A number of pandrug resistant (PDR) (20 .0% ,1 567/7 827) and multidrug-resistant (MDR) (45 .0% , 3 521/7 827 ) A . baumannii were identified . Conclusions A . baumannii is the most popular pathogenic bacteria among Acinetobacter .The antibiotic resistance of A .baumannii is still increasing .Cefoperazone-sulbactam and minocycline has good in vitro antibacterial activity against A .baumannii .The antibiotic resistance of A .baumannii varies greatly with hospital and department .
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Objective To investigate the antimicrobial resistance of clinical strains of K lebsiella spp .isolated from 15 hospitals in China CHINET during 2012 .Methods Kirby-Bauer method and automatic microbiology analysis system were employed to study the antimicrobial resistance . WHONET 5 .6 software was applied for data analysis according to Clinical and Laboratory Standards Institute (CLSI) 2012 breakpoints .Results A total of 9 621 clinical K lebsiella isolates were analyzed ,including 8 772 strains of K . pneumoniae and 804 strains of K . oxytoca . About 54 .9% (5 285/9 621) of the K lebsiella strains were isolated from sputum ,and 16 .3% (1 564/9 621) were isolated from pediatric patients .Antimicrobial susceptibility testing showed that about 8 .9% ,10 .8% and 12 .9% of the strains were resistant to imipenem ,meropenem and ertapenem ,respectively .About 14 .1% and 17 .0% of the strains were resistant to piperacillin-tazobactam and cefoperazone-sulbactam , respectively . Carbapenem-resistant K lebsiella strains were identified from all the 15 hospitals ,including 945 strains of K .pneumoniae and 45 strains of K .oxytoca ,which were resistant to either imipenem ,meropenem or ertapenem .Conclusions The Klebsiella isolates collected from 15 hospitals in China during 2012 are relatively sensitive to carbapenems ,cefoperazone-sulbactam and piperacillin-tazobactam .The prevalence of carbapenem-resistant strains is still increasing in China ,about 10 .3% in 2012 ,and relatively higher in Eastern China .More efforts should be made to control the superbug .
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Objective To investigate the species and drug resistance of pathogens causing bloodstream infections in hospitalized patients,and provide scientific evidence for antimicrobial use and control of healthcare-associated blood-stream infection.Methods From January 1 to December 31,2012,16 428 blood specimens were performed blood culture,pathogens were isolated and performed antimicrobial susceptibility testing.Results Of 16 428 blood speci-mens from 5 546 patients,384 (6.92%)were positive for blood culture,398 pathogenic isolates were detected,of which gram-positive bacteria,gram-negative bacteria,and fungi accounted for 23.62% (n=94),68.34% (n=272),and 8.04% (n=32)respectively,positive rate of blood culture were highest in 61-80 age group(8.26%), the top five departments of positive rate of blood culture were departments of burn,traditional Chinese medicine, cardiac intensive care unit,transplantation and traumatology;gram-positive cocci were highly susceptible to vanco-mycin,teicoplanin and linezolid,one Enterococcus faecium strain was found to be resistant to vancomycin;Among gram-negative bacilli,Enterobacteriaceae were highly susceptible to amikacin and carbapenems;drug resistance rates of Acinetobacterbaumannii and Pseudomonasaeruginosa to carbapenems was 70.97% and 35.90% respective-ly.Conclusion Gram-negative bacteria are the major pathogens causing bloodstream infection,positive rate of blood culture of elderly people is high.It is necessary to conduct regular surveillance on distribution and drug resistance of pathogens.
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Objective To investigate the resistance of clinical Stenotrophomonas maltophilia isolates from 15 hospitals in several regions of China during 2011.Methods Fifteen repre-sentative general hospitals were involved in this program. Bacterial susceptibility testing was carried out by means of a unified protocol using Kirby-Bauer method and MIC determi-nation.Results were analyzed according to CLSI 2011 break-points.Results Majority (93.3%) of the 1 889 clinical strains of S.maltophilia were isolated from inpatients.On-ly 6.7% of the isolates were from outpatients.About 62.9% of these S .maltophilia strains were isolated from old patients whose age was 60 years or older.Only 8.2% of the strains were from the patients younger than 18 years old.Sputum and re-spiratory tract secretion were the most common specimen source,accounting for 82.6%.Another 4.2% isolates were from blood,abdominal fluid and other sterile body fluids.The percentage of the S .maltophilia strain resistant to trimethoprim-sul-famethoxazole,levofloxacin and minocycline was 16.6%,10.0% and 1.8%,respectively.The strains resistant to cefopera-zone-sulbactam accounted for 19.0%.About 37.1% of the strains isolated from blood or sterile body fluids were resistant to trimethoprim-sulfamethoxazole,significantly higher than the strains from urine or wound specimens (P < 0.01).Conclusions S.maltophilia strains are mainly isolated from inpatients.The most common source is sputum and other respiratory speci-mens.Most of the patients with S.maltophilia isolate are 60 years of age or older.The S.maltophilia strains are constitu-tively resistant to several antibacterial agents,but showed relatively lower resistance to trimethoprim-sulfamethoxazole,levo-floxacin and minocycline.Cefoperazone-sulbactam is still active against these strains.The antimicrobial therapy targeting S. maltophilia infections should be selected cautiously according to the results of antimicrobial resistance surveillance.
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Objective To investigate the prevalence and main genotypes of carbapenemases in carbepenem‐resistant Enterobacteriaceae (CRE) .Methods A total of 114 strains of CRE were isolated in Shanghai Ruijin Hospital from May 2011 to June 2013 .The diameter of inhibition zone of imipemen or meropenem for these strains was not larger than 22 mm .PCR method was used to screen for the main carbapenemase genes (blaKPC ,blaIMP ,blaVIM ,blaOXA‐48 and blaNDM ) with previously described primers followed by nucleotide sequencing analysis . Conjugation experiments were performed to examine the transferability of plasmids .Pulsed‐field gel electrophoresis (PFGE) was used to show the relatedness of KPC‐2‐producing Enterobacteriaceae .Results Most of the 114 isolates were K lebsiella pneumoniae and Escherichia coli .Of the 114 isolates ,98 was positive for carbapenemases ,specifically ,78 blaKPC‐2‐positive ,15 blaIMP‐4‐positive ,2 blaIMP‐8‐positive ,1 positive for both blaKPC‐2 and blaIMP‐4 and 4 blaNDM‐1‐positive .None of the strains was positive for blaOXA‐48 or blaVIM .About 21 .4% (21/98) of the isolates were conjugated successfully .The 49 blaKPC‐2‐positive K .pneumoniae isolates were grouped into 12 types according to PFGE patterns .Majority (34/49) of these isolates belonged to the same type A .Conclusions BlaKPC‐2 was the primary epidemic genotype of Enterobacteriaceae in Ruijin Hospital ,followed by blaIMP‐4 .NDM‐1 carbapenemase was produced in 4 strains of CRE . Meanwhile , clonal spread of KPC‐2‐producing K . pneumoniae was observed in some departments of our hospital , such as surgical ICU , respiratory medicine and thoracic surgery . Appropriate measures should be taken timely and effectively to prevent the in‐hospital spread of resistant genes .
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Objective To investigate the relationship between antibiotic use and antimicrobial resistance in Acinetobacter bau-mannii for rational use of antibiotics.Methods Antibiotic use density (AUD)of common antibiotics in hospitalized patients were collected in a tertiary hospital between 2006 and 2010.Clinical isolates of A.baumannii from those patients were collect-ed.The resistance to common antimicrobial agents were tested by disk diffusion method according to Clinical and Laboratory Standards Institute (CLSI,2012)guidelines.Relationship between antibiotic use and antimicrobial resistance in A.baumannii was analysed by SPSS 16.0.Results The resistant rates of A.baumannii isolated from inpatients were high.Consumption of cephalosporins and quinolones were large.There was a positive correlation between the resistant rate of A.baumannii to imi-penem and AUD of carbapenems (r=0.975,P <0.05).The resistant rate of A.baumannii to meropenem showed significantly positive relation to AUD of carbapenems (r= 0.975,P <0.05).Resistant rates of aminoglycosides,quinolones,cephalospo-rins and beta-lactamase inhibitors was not correlated to AUD of those antibiotics.Conclusions We should pay more attention to the high prevalence of resistant A.baumannnii strains.Application of imipenem and meropenem should be strictly controlled.Amikacin and beta-lactamase inhibitors are better choice for empirical antibiotic therapy in the treatment of infections caused by A. baumannii.
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Objective To evaluate the practicability of CHROMagar orientation medium combined with simple biochemical tests for identification of common oxidase-negtive gram-negative bacilli.Methods The CHROMagar orientation medium was used together with biochemical tests including indole test , ornithine decarboxylase test and lysine decarboxylase test for identification of common oxidase -negtive gram-negative bacilli.The sensitivity, specificity, likelihood ratio, Youden index and Kappa value of the diagnostic assays were evaluated .McNemar test was performed to evaluate facticity, accuracy and cost of the method in com-parison with the Vitek-2 system as reference method .Results The identification of oxidase-negtive gram-negative bacilli from 318 bacterial strains showed that the sensitivities and specificities of CHROMagar orien-tation mediumm in combination with simple biochemical tests to Serratia marcescens, Stenotrophomonas mal-tophilia and Acinetobacter baumannii reached 100%, and for Escherichia coli, Enterobacter aerogenes and Klebsiella pneumoiae were above 90%.The specificities for identification of Enterobacter cloacae, Klebsiella oxytoca, Citrobacter freundii and Proteus mirabilis were all above 90%, but the sensitivities were around 75%-90%.Kappa values of the assays were above 0.85, howerer, which was only 0.5947 for Citrobacter freundii.McNemar test showed that all P values were above 0.05, and cost of the assays was reduced by 90%.Conclusion CHROMagar orientation medium in combination with simple biochemical tests is a cost-effective assay for identification of common oxidase-negtive gram-negative bacilli .