Chinese consensus guidelines for therapeutic drug monitoring of polymyxin B, endorsed by the Infection and Chemotherapy Committee of the Shanghai Medical Association and the Therapeutic Drug Monitoring Committee of the Chinese Pharmacological Society / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

Polymyxin B, which is a last-line antibiotic for extensively drug-resistant Gram-negative bacterial infections, became available in China in Dec. 2017. As dose adjustments are based solely on clinical experience of risk toxicity, treatment failure, and emergence of resistance, there is an urgent clinical need to perform therapeutic drug monitoring (TDM) to optimize the use of polymyxin B. It is thus necessary to standardize operating procedures to ensure the accuracy of TDM and provide evidence for their rational use. We report a consensus on TDM guidelines for polymyxin B, as endorsed by the Infection and Chemotherapy Committee of the Shanghai Medical Association and the Therapeutic Drug Monitoring Committee of the Chinese Pharmacological Society. The consensus panel was composed of clinicians, pharmacists, and microbiologists from different provinces in China and Australia who made recommendations regarding target concentrations, sample collection, reporting, and explanation of TDM results. The guidelines provide the first-ever consensus on conducting TDM of polymyxin B, and are intended to guide optimal clinical use.

Antimicrobial resistance changes of carbapenem-resistant Enterobacteriaceae strains isolated from children / 中华儿科杂志

Objective@#To investigate the prevalence and resistance changes of carbapenem-resistant Enterobacteriaceae (CRE) strains isolated from children patients of Chinese Bacterial Resistance Surveillance Network (CHINET) from 2005 to 2017.@*Methods@#Antimicrobial susceptibility testing was carried out by disk diffusion method (KB method) and automated systems. Results were analyzed according to the Clinical and Laboratory Standards Institute (CLSI) 2017 edition standards.@*Results@#Among the 4 481 CRE clinical strains, the overall prevalence of CRE in children was 6.4%, including 8.8% in neonatal period, 7.3% in infancy, 3.8% in early childhood, 4.0% in preschool, 4.7% at school age and 7.4% of puberty. The CRE prevalence of citrobacter spp. remained stable in 2005-2017, whereas other bacteria showed an upward trend, which was higher than that of the adult group (P<0.01). Among the 4 481 CRE strains, there were 2 905 strains of Klebsiella spp. (64.8%), 813 strains of Escherichia coli (18.1%), 549 strains of Enterobacter spp.(12.3%), and 65 strains of Citrobacter spp.(1.5%). Among the 4 481 CRE strains, 20.7%, 13.3%, and 11.8% were from the intensive care unit (ICU), neonatal department and internal medicine wards, respectively. Specimens were distributed as respiratory (42.8%), urine (26.3%), and blood (14.9%). The results of antimicrobial susceptibility testing exhibited that the CRE strains were highly resistant to most commonly used antimicrobial agents in clinical practice, such as imipenem, meropenem and ertapenem, as well as penicillins and cephalosporins, etc.@*Conclusion@#The prevalence of CRE strains in children is increasing year by year, and their antimicrobial resistance to common antibacterial agents in clinical practice is extremely serious, to which serious attention needs to be paid. According to the results of antimicrobial susceptibility testings, the antibacterial agents should be rationally selected to effectively control the spread of CRE.

Fluoroquinolone resistance profile of Klebsiella pneumoniae isolates and the mechanisms conferring antibiotic resistance in ST494 strains / 中国感染与化疗杂志

Objective To investigate the resistance profile of Klebsiella pneumoniae isolates in Huashan Hospital, Fudan University. Methods The MICs of fluoroquinolones were determined by agar dilution method against 112 clinical strains of K. pneumoniae. Multilocus sequence typing (MLST) were applied to 48 K. pneumoniae strains. The characteristic sequence type (ST) associated with antibiotic resistance was identified by PCR. Results Lower percentage (＜40％) of K. pneumoniae strains were susceptible to fluoroquinolones. Majority (86.2％) of ciprofloxacin non-susceptible K. pneumoniae strains belonged to CC1 (ST11), ST494 or CC4 (ST15 and ST655), indicating the potential of clonal dissemination. ST494 (18.8％) was the second commonest sequence type, next only to ST11. ST494 strains harbored the genes encoding beta-lactamases, oqxAB, qnrD, aac-(6')-lb-cr and armA and had a single point mutation in gyrA. Therefore, ST494 strains were highly resistant to cephalosporins, fluoroquinolones and aminoglycosides and 22％ of the strains were resistant to carbapenems. However, all the ST494 strains were susceptible to tigecycline and tetracycline. Conclusions ST11 and ST494 are the commonest STs of K. pneumoniae conferring multidrug resistance in this hospital. These STs may contribute to the high resistance rates of K. pneumoniae to fluoroquinolones. The susceptibility of ST494 strains to tigecycline and tetracycline allows us to consider the promising potential of such drugs in managing K. pneumoniae infections.

Antimicrobial resistance profile of clinical isolates in hospitals across China: report from the CHINET Surveillance Program, 2017 / 中国感染与化疗杂志

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.

CHINET surveillance of bacterial resistance across China: report of the results in 2016 / 中国感染与化疗杂志

Objective To investigate the susceptibility profile of clinical isolates collected from hospitals across China.Methods Twenty-six general hospitals and four 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 2016 breakpoints.Results A total of 153 059 clinical isolates were collected from Junuary to December 2016,of which gram-negative organisms and gram-positive cocci accounted for 71.6％ and 28.4％,respectively.The overall prevalence of methicillin-resistant strains was 38.4％ in S.aureus (MRSA) and 77.6％ in coagulase negative staphylococcus (MRCNS),respectively.The resistance rates of methicillin-resistant strains to most of other antimicrobial agents were much higher than those of methicillin-susceptible strains.However,92.3％ of the MRSA strains were still sensitive to trimethoprim-sulfamethoxazole,while 86.5％ of the MRCNS strains were susceptible to rifampin.No staphylococcal strains were found resistant to vancomycin or teicoplanin.The resistance rates of E.faecalis strains to most drugs tested (except chloramphenicol) were much lower than those of E.faecium.A few strains of both species were resistant to vancomycin.Vancomycin resistant E.faecalis and E.faecium strains were mainly VanA,VanB or VanM type based on their phenotype or genotype.Regarding the non-meningitis S.pneumoniae strains,the prevalence of PSSP or PISP strains isolated from children was higher than that isolated in 2015,but the prevalence of PRSP strains decreased.However,the prevalence of PISP and PRSP strains isolated from adults was lower than that isolated in 2015.The prevalence of ESBLs-producing strains was 45.2％ in E.coli,25.2％ 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 rate.The strains of Enterobacteriaceae were still highly susceptible to carbapenems.Overall,less than 10％ of these strains were resistant to carbapenems.About 68.6％ and 71.4％ ofAcinetobacter spp.(A.baumannii accounts for 90.6％) strains were resistant to imipenem and meropenem,respectively.The prevalence of extensively-drug resistant strains in P.aeruginosa was higher than that in 2015.Conclusions Bacterial resistance to commonly used antibiotics is still on the rise.It is necessary to strengthen hospital infection control and management of clinical use of antimicrobial agents,and maintain good practice in surveillance of bacterial resistance.

Susceptibility and prevalence of blaKPC gene in carbapenem-resistant Klebsiella pneumoniae / 中国感染与化疗杂志

Objective To examine the antimicrobial susceptibility and prevalence of blaKPC gene in carbapenem-resistant Klebsiella pneumoniae (CRKP) strains isolated in Huashan Hospital,Fudan University.Methods The CRKP strains isolated in Huashan Hospital from January to December of 2014 were included in this study.The MICs of antibiotics were determined using CLSI broth dilution method.The blaKPC gene was amplified by polymerase chain reaction (PCR).Results A total of 205 CRKP strains were isolated,mainly from respiratory tract (76.1％,156/205) and urine specimens (18.5％,38/205).Antimicrobial susceptibility test indicated that CRKP isolates had higher resistance rates (85％-100％) to the antimicrobial agents except colistin (1.5％),tigecycline (0.5％),trimethoprim-sulfamethoxazole (51.0％) and amikacin (74.9％).Most (87.8％,180/205) of the CRKP strains were positive for blaKPC gene.Conclusions CRKP are mostly isolated from patients with lower respiratory tract infection and/or urinary tract infection in Huashan Hospital.The strains were highly resistant to the antibacterial agents tested except colistin and tigecycline.Production of KPC-type carbapenemase is the common mechanism of carbapenem resistance in these K.pneumoniae isolates.

Characterization and genomic analysis of bacteriophage SH-Kp152234 infecting extensively drug-resistant Klebsiella pneumonia / 上海交通大学学报（医学版）

Objective · To identify broad-spectrum bacteriophages against extensively drug-resistant Klebsiella pneumonia and analyze their characteristics by biological and genomic methods. Methods · Multi-drug resistant Klebsiella pneumonia strains collected from a hospital were used as host bacteria to isolate and purify broad-spectrum phages in the wastewater at the same hospital area. The size and shape of phages were observed by transmission electron microscope. Titer, host range, pH stability and thermal stability were measured. Moreover, the DNA extracted from the phage SH-Kp152234 was sequenced and analyzed. Results · One strain of bacteriophage against Klebsiella pneumonia was isolated and named as SH-Kp152234. The electron microscope revealed it belongs to Podoviridae family. Moreover, genome of SH-Kp152234 showed to be a linear double-stranded DNA of 40578 bp with the GC content of 52.85%. It was predicted to have 49 open reading frames with related known functions.Conclusion · SH-Kp152234, with a broad host range and a short latent period, which could exert its activity in a wide range of temperature and pH, is a promising candidate to be exploited in the treatment of multiple drug-resistant Klebsiella pneumonia.

In vitro antimicrobial susceptibility and virulence genes of the Staphylococcus aureus strains isolated from blood and sterile body fluids / 中国感染与化疗杂志

Objective To investigate the antimicrobial susceptibility and associated virulence genes of the Staphylococcus aureus?strains?isolated?from?blood,?cerebrospinal?fluid?and?other?sterile?body?fluids?in?Huashan?Hospital?from?year?1999?to?2014.?Methods MIC values of vancomycin and other antibiotics against S. aureus were measured by agar dilution method. Resistant genes mecA and mecC and virulence genes PVL and sasX were detected by PCR in the S. aureus strains. Results The overall prevalence of MRSA in S. aureus was 54.3 % (140 / 258) and 45.7 % (118 / 258) for MSSA. Resistance rates of MRSA to most antimicrobial agents were higher than MSSA. MSSA strains were still sensitive to all the antibiotics tested, resistance rate not higher than 11% except penicillin. MIC90?values?of?β-lactam?antibiotics?(except?penicillin)?to?MSSA?were?lower?than?1?mg?/?L.?No? staphylococcal strains were found resistant to vancomycin, teicoplanin or linezolid. The mecA gene was present in all the 90 MRSA strains, and sasX gene in 46.7% of the strains. The prevalence?of?MRSA?isolated?from?blood,?cerebrospinal?fluid?and?other?sterile?body?fluids?decreased?year?by?year.?No?mecC gene?or?PVL?gene?was?identified?in?these?MRSA?strains.?Both?sasX-positive MRSA and sasX-negative MRSA were resistant to?β-lactam?antibiotics,?fosfomycin?and?levofloxacin.?The?sasX-positive MRSA strains showed higher resistance rates to amikacin and trimethoprim-sulfamethoxazole than sasX-negative MRSA. Conclusions? The?MRSA?strains?isolated?from?blood,?cerebrospinal?fluid?and?other?sterile?body?fluids?in?Huashan?Hospital?were?resistant to most commonly used anbiotics. MRSA surveillance is critical for rational use of antimicrobial agents.

Surveillance of antibiotic resistance among the bacterial strains isolated from hospitals in Shanghai: results of 2016 / 中国感染与化疗杂志

Objective To investigate the resistance profile of clinical bacterial isolates to antibiotics in Shanghai during 2016.Methods Antimicobial susceptibility testing was carried out for the clinical isolates collected from 47 hospitals according to a unified protocol using Kirby-Bauer method or automated systems.The participating hospitals included 28 tertiary hospitals and 19 secondary hospitals across Shanghai.Results were analyzed according to CLSI 2016 breakpoints.Results A total of 122 548 clinical isolates were collected,including 35 522 (29.0％) strains of gram positive cocci and 87 026 (71.0％) strains of gram negative bacilli.Overall,28.9％ of the isolates were from secondary hospitals and 71.1％ from tertiary hospitals.Gram positive and gram negative isolates accounted for 25.8％ and 74.2％ in secondary hospitals,30.3％ and 69.7％ in tertiary hospitals,respectively.The overall prevalence of MRSA in Staphylococcus aureus was 48.7％ and 77.2％ of MRCNS in coagulase-negative Staphylococcus.The average prevalence of MRSA and MRCNS was 55.9％ and 73.3％ in secondary hospitals,45.9％ and 78.6％ in tertiary hospitals.No strains were found resistant to vancomycin in Staphylococcus.About 77.4％ of the 1 111 strains of non-meningitis S.pneumoniae isolated from children were penicillin-susceptible (PSSP),13.2％ were penicillin-intermediate (PISP) and 9.4％ were penicillinresistant (PRSP).The prevalence of PSSP,PISE and PRSP was 97.8％,2.2％,and 0 in secondary hospitals,76.5％,13.7％,and 9.8％ in tertiary hospitals.Of the 285 strains isolated from adults,94.0％,4.2％ and 1.8％ were PSSP,P1SP and PRSP,respectively.The prevalence of PSSP,PISP and PRSP among the isolates from adults was 93.7％,5.3％,and 1.0％ in secondary hospitals,94.2％,3.7％,and 2.1％ in tertiary hospitals.Overall,37 strains of vacomycin-resistant E.feacium (14 from secondary hospitals and 23 from tertiary hospitals) and 25 strains of vacomycin-resistant E.feacalis (all from tertiary hospitals) were identified.PCR and sequencing analysis indicated that most of these resistant strains were vanA type.The overall prevalence of ESBLs-producing srains was 52.2％ in E.coli,30.9％ in Klebsiella pneumoniae and 29.8％ in Proteus mirabilis.Specifically,the corresponding prevalence of such strains was 55.1％,33.6％ and 34.0％ in secondary hospitals,51.0％,29.7％ and 28.0％ in tertiary hospitals,respectively.Enterobacteriaceae strains were still highly susceptible to carbapenem antibiotics.Overall,8.9％ and 9.1％ of the Enterobacteriaceae strains were resistant to imipenem and meropenem,respectively.The figure was 6.6％ and 7.1％ in secondary hospitals,9.9％ and 10.0％ in tertiary hospitals.Extensively drug-resistant strains were identified in A.baumannii,K.pneumoniae,P.aeruginosa,and E.coli,specifically,223,63,10,and 4 strains in secondary hospitals;224,201,22,and 9 strains in tertiary hospitals.Conclusions Antibicotic resistance is still very serious in the common clinical strains,which poses a critical threat to healthcare facilities.This issue should be taken seriously and effective infection control measures must be put in place.

In vitro activity of tigecycline and minocycline against Van M-type vancomycin-resistantEnterococcus faecium / 中国感染与化疗杂志

Objective To investigate thein vitro activity of tigecycline and minocycline against VanM-type vancomycin-resistant Enterococcusfaecium.Methods A total of 45 strains of VanM-type vancomycin-resistantE. faecium were obtained from hospitals in Shanghai between 2006 and 2014. Species and vancomycin resistance genotype were identiifed by PCR and sequencing analysis. Minimal inhibitory concentrations (MICs) of ten antimicrobial agents against these strains were determined.Results All the 45 isolates were VanM-type vancomycin-resistantE. faecium, and resistant to vancomycin (MIC: 128 to >256 mg/L). And 71.1%of the strains were resistant to teicoplanin. Almost all isolates showed resistance to levolfoxacin (100%) and ampicillin (97.8%). About 15.6%, 64.4% and 82.2% of the strains were resistant to minocycline, gentamicin and rifampicin, respectively.Conclusion Tigecycline and minocycline exhibit excellentin vitro activity against these VanM-type vancomycin-resistantE. faecium isolates.

Changing susceptibility ofKlebsiella strains in hospitals across China：data from the CHINET Antimicrobial Resistance Surveillance Program, 2005-2014 / 中国感染与化疗杂志

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.

Changing resistance proifle ofProteus, Serratia, Citrobacter, Morganella andProvidencia isolates in hospitals across China：data from CHINET Antimicrobial Resistance Surveillance Program 2005-2014 / 中国感染与化疗杂志

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.

Antibiotic resistance profile of the bacterial strains isolated from geriatric patients in hospitals across China：data from CHINET Antimicrobial Resistance Surveillance Program 2005-2014 / 中国感染与化疗杂志

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.

Analysis of polymyxin susceptibility in Enterobacteriaceae / 中国感染与化疗杂志

Objective To investigate the distribution and antimicrobial susceptibility of clinical strains ofEnterobacteriaceae isolated from Huashan Hospital in 2014.MethodsEnterobacteriaceae were isolated from January to August 2014. Antimicrobial susceptibility testing was performed by agar dilution method. TheblaKPC gene was screened by PCR and DNA sequencing. Results were analyzed by WHONET 5.6 software.Results A total of 719 strains ofEnterobacteriaceae were collected, of whichKlebsiella spp., andE .coli accounted for 43.8% (315/719) and 30.4% (219/719), respectively. Resistance rates ofKlebsiella spp.,E. coli, andCitrobacter spp., to polymyxin B and polymyxin E were low (<3%). The percentage of theEnterobacter strains resistant to polymyxin B and polymyxin E was 10.9% and 11.1%, respectively. About 47.5% and 44.7% of theSerratia strains were resistant to polymyxin B and polymyxin E, respectively. More than 90% of theMorganella andProteus isolates were resistant to polymyxin B or polymyxin E. The carbapenem-resistantEnterobacteriaceae strains were mainly identiifed inKlebsiella isolates, more than 40% of which were resistant to meropenem and ertapenem, but only 2.9% and 2.6% were resistant to polymyxin B and polymyxin E, respectively. Ertapenem resistance was identified in 27.8% of theCitrobacter isolates and 17.9% of theSerratia isolates. Less than 10% of the otherEnterobacteriaceae strains were resistant to carbapenem. Overall, 20.7% (149/719) of the isolates wereblaKPC positive, mainly inK. pneumoniae (129/315, 41.0%). Seven strains ofSerratia marcescens and 2 strains ofK. Pneumoniae were resistant to both carbapenems and polymyxin.Conclusions The clinical isolates ofKlebsiella, E. coli, Enterobacter andCitrobacter in 2014 were still highly susceptible to polymyxin antibiotics.

Fosfomycin resistance and f os gene detection in clinical St ap hy lococcus aureus strains / 中国感染与化疗杂志

Objective To understand fosfomycin resistance and prevalence of fos gene in clinical Staphylococcus aureus strains . Methods A total of 109 clinical strains of S .aureus were isolated from the patients in Huashan Hospital from January to March in 2014 .Antimicrobial susceptibility testing was performed by agar dilution method .The genes related to fosfomycin resistance including fosA ,fosB and fosC were detected by PCR .The flanking sequences of fos gene were determined by primer walking sequencing .The multilocus sequence typing (MLST) was carried out for fos gene positive strains .Results Forty‐four strains were resistant to fosfomycin (MIC> 32 mg/L) ,including 13 positive for fosB gene .Thirteen of the 109 (11 .9% ) strains carried fosB gene .However ,no fosA or fosC gene was identified .ST1 was a dominant MLST type in the strains carrying fosB gene .The three strains positive for fosB gene and associated with high level fosfomycin resistance (MIC> 512 mg/L) belonged to three different ST types . Walking sequencing showed that the fosB gene located on a transferable element containing a transposase gene .Conclusions High prevalence of f osB gene in fosfomycin‐resistant S . aureus strains indicates that f osB gene may mediate or contribute to fosfomycin resistance .

CHINET 2014 surveillance of bacterial resistance in China / 中国感染与化疗杂志

Objective To investigate the susceptibility and resistance of clinical isolates from hospitals in several regions of China .Methods Fifteen 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 2014 breakpoints .Results A total of 78 955 clinical isolates were collected from January to December 2014 ,of which gram negative organisms and gram positive cocci accounted for 72 .6% and 27 .4% ,respectively . Methicillin‐resistant strains in S .aureus(MRSA)and coagulase negative Staphylococcus(MRCNS)accounted for an average of 44 .6% and 83 .0 % ,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 .0% of MRSA strains were still susceptible to trimethoprim‐sulfamethoxazole ,while 85 .6% 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 V anA ,V anB or V anM type based on their phenotype or genotype .Regarding non‐meningitis S .pneumoniae strains ,the prevalence of penicillin‐susceptible S .pneumoniae strains isolated from both adults and children were higher than those isolated in 2013 ,but the prevalence of penicillin‐intermediate S . pneumoniae or penicillin‐resistant S . pneumoniae strains decreased . The prevalence of ESBLs producingstrainswas55.8% in E.coliand29.9% in Klebsiellaspp.(K.pneumoniaeand K.oxytoca)and24.0% 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 10 % of these strains were resistant to carbapenems . About 62 .4% and 66 .7% of Acinetobacter spp .(A .baumannii accounts for 93 .0 % ) strains were resistant to imipenem and meropenem ,respectively . Compared with the data of year 2013 ,extensively‐drug resistant strains in K . pneumoniae and A .baumannii increased . Conclusions The antibiotic resistance of clinical bacterial isolates is growing .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 .

CHINET 2011 surveillance of antibiotic resistance in Stenotrophomonas malto-philia in China / 中国感染与化疗杂志

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.

CHINET 2013 surveillance of bacterial resistance in China / 中国感染与化疗杂志

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 .

CHINET surveillance of distribution and susceptibility of carbapenem-resistant Enterobacteriaceae isolates in 2012 / 中国感染与化疗杂志

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 .

CHINET 2012 surveillance of antibiotic resistance in Enterobacter spp .in China / 中国感染与化疗杂志

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 .