Pathogenic bacteria spectrum of infectious stones and experience of preventing stone recurrence / 中华泌尿外科杂志

Objective:To investigate the pathogenic bacteria profiles in preoperative urine bacterial cultures of patients with infected kidney stones and use antibacterial drugs to prevent recurrence.Methods:The data of 79 cases with infected kidney stones admitted to the Second Affiliated Hospital of Zhengzhou University from January 2017 to July 2021 were retrospectively analyzed, among whom 29 (36.7%) were male and 50 (63.3%) were female. The age ranged from 17-75 years, with a median age of 49.0 (40, 55) years. Fifteen cases (19.0%) combined hypertension, 13 cases (16.5%) combined diabetes mellitus, and 3 cases (3.8%) combined with cardiovascular disease. Fifty-one cases (64.6%) were diagnosed with cast infectious stones. All patients underwent surgical lithotripsy, and postoperative review of the urological computerized tomography (CT) revealed no residual stones defined as complete lithotripsy, and postoperative oral medication was continued to control infection and prevent stone recurrence. According to post-hospitalization compliance, patients were divided into high and low compliance groups. The high compliance group consisted of patients who returned to the hospital regularly for routine urinalysis and urine bacterial culture after discharge, followed the doctor's prescription for standardized antibacterial drug therapy, and complied with urease inhibitor therapy for ≥6 months. The low compliance group included patients who did not take sensitive antimicrobial drugs regularly and/or were unable to adhere to the medication even after the reduction of vinblastine due to adverse events such as tremor, palpitations, headache, anemia, or gastrointestinal discomfort. The recurrence of stones at 3, 6 and 12 months of follow-up was compared between the two groups.Results:Of the 79 cases in this group, 56(70.9%) were completely clear of stone after surgery. Thirty-three cases (41.8%) presented positive in preoperative urine bacterial culture, and the most common causative organism was Aspergillus oddus in 17 cases (21.5%), followed by Escherichia coli in 8 cases (10.1%) and Klebsiella pneumoniae in 3 cases (3.8%). Among the 17 positive cases of A. oddis, six were positive for ultra broad spectrum β-lactamases (ESBLs), 6/6 were resistant to ampicillin, cefazolin, and cotrimoxazole, 1/6 were resistant to amikacin, cefoxitin, and ticarcillin/stick acid, and none were resistant to imipenem, polymyxin, or aminotrans (0/6 cases). Of the cases, 11 were negative for ESBLs. Ten out of eleven cases were resistant to ampicillin. Furthermore, 8/11 cases were resistant to cefazolin, levofloxacin, ciprofloxacin, and cotrimoxazole and 1/11 were resistant to cefoxitin, cefaclor, furantoin, amikacin, and minocycline, and 0/11 were resistant to imipenem, ticarcillin/stick acid, aminotrans. ESBLs positive strains were resistant to 78.6% of the tested drugs (cefaclor, cefazolin, ceftazidime, furantoin, norfloxacin, levofloxacin, ciprofloxacin, cefoxitin, amoxicillin/rod acid, ticarcillin/rod acid, ampicillin, ceftriaxone, cefotaxime, cefuroxime, cefepime, gentamicin, cotrimoxazole, tobramycin, amikacin, tetracycline, chloramphenicol, and minocycline) at a lower rate of resistance than ESBLs positive strains. Of the eight positive cases of E. coli, seven were ESBLs positive, 7/7 were resistant to ampicillin, cefazolin, cefotaxime, cefuroxime, and cefepime, 1/7 were resistant to cefoxitin and minocycline, and 0/7 were resistant to imipenem, furantoin, or amikacin. One case was ESBLs negative and was resistant to all antimicrobial drugs except for ampicillin. Stone recurrence rates at 3, 6, and 12 months after discharge were 9.1%(4/44) and 31.4%(11/35), 13.6%(6/44), respectively, in the high compliance group, and 60.0%(21/35), 36.4%(16/44), and 71.4% (25/35), respectively, in the low compliance group. All differences were statistically significant.Conclusion:The most common pathogenic bacteria isolated from urine bacterial cultures of patients with infectious stones were A. chimaera, E. coli, and K. pneumoniae. The resistance rate of ESBLs-positive strains to antimicrobial drugs was significantly higher than that of ESBL-negative strains, and the resistance rate of antimicrobial drugs such as β-lactamase inhibitors, cefoxitin, amikacin, and imipenem was low. Combination therapy with standardized sensitive antimicrobial drugs and urease inhibitors significantly reduced the recurrence rate of stones among patients.

Genomic characteristics of a Klebsiella pneumoniae strain coproducing carbapenemases KPC-2 and NDM-5 / 中华微生物学和免疫学杂志

Objective:To analyze the characteristics of drug resistance genes in a Klebsiella pneumoniae strain coproducing carbapenemases KPC-2 and NDM-5. Methods:Klebsiella pneumoniae KPN-hnqyy was separated from the stool specimen of a patient in the Hematology Department of Affiliated Cancer Hospital of Zhengzhou University. The strain was identified with a BD Phenix-M50 automated microbiology system and the minimum inhibitory concentration against the strain was measured as well. The genotypes of the carbapenemases were tested by enzyme immunochromatographic assay and PCR method. The transferability of related plasmids was analyzed by conjugation test. Whole-genome sequencing of the strain was conducted using PacBio and Illumina platforms. The MLST type, resistance gene and plasmid type of the strain were retrieved in BacWGSTdb. The genome and open reading frame sequence of the strain were compared using Easyfig_2.2.3. Visual cycle graphs were generated using BRIG v0.95. Results:Klebsiella pneumoniae KPN-hnqyy was resistant to carbapenem antibiotics. It belonged to ST11 and carried two carbapenemase genes of blaKPC-2 and blaNDM-5. The conjugant only harbored the blaKPC-2 gene. Whole-genome sequencing revealed that the strain contained one chromosome and three plasmids. Its chromosome genome shared more than 99.9% similarity with that of Klebsiella pneumonia KP69 and KP19-2029. Moreover, a similar IncR and IncFⅠ resistance gene fusion region was contained in different types of plasmids carried by them: the blaKPC-2 gene was located in a structure—which evolved from the Tn3-△Tn4401-Tn1721/Tn1722 sequence—inside this fusion region with its ends inserted into the transposase IS26 gene; the blaNDM-5 gene was located on a transposon containing the special plasmids of the insertion fragment in phages, with its ends inserted into the transposase IS26 gene too. Conclusions:The IncR and IncFⅡ resistance gene fusion region of blaKPC-2 carried by Klebsiella pneumoniae ST11 might be widely coexistent with the chromosomal genome. The blaNDM-5 gene carried by special plasmids might be accidentally obtained through gene recombination mediated by transposable element IS26. The wide transmission of Klebsiella pneumoniae ST11 carrying the blaKPC-2 gene in China and its ability to obtain other carbapenemase genes through transposable element IS26 were well worth attention.

Recent developments in the medicinal chemistry of single boron atom-containing compounds

Various boron-containing drugs have been approved for clinical use over the past two decades, and more are currently in clinical trials. The increasing interest in boron-containing compounds is due to their unique binding properties to biological targets; for example, boron substitution can be used to modulate biological activity, pharmacokinetic properties, and drug resistance. In this perspective, we aim to comprehensively review the current status of boron compounds in drug discovery, focusing especially on progress from 2015 to December 2020. We classify these compounds into groups showing anticancer, antibacterial, antiviral, antiparasitic and other activities, and discuss the biological targets associated with each activity, as well as potential future developments.

The distribution of CTX-M drug resistance genotypes in Escherichia coli isolated from urethra in children and the influence of pH changes on its drug resistance / 临床儿科杂志

Objectives To explore the distribution of CTX-M drug resistance genotypes in Escherichia coli isolated from urethra in children and the influence of pH changes on its drug resistance. Methods A total of 113 strains of Escherichia coli isolated from clean midstream urine in children with urinary tract infection were cultured from October 2013 to May 2014. The drug sensitivity of ESBL-producing Escherichia coli was detected and counted. The distribution of CTX-M drug resistance genotypes were analyzed by PCR and gene sequencing. Different pH environment was established in vitro to evaluate the effect of pH on drug resistance of CTX-M resistant Escherichia coli. Results In 113 Escherichia coli strains, there were 68 ESBL-producing strains (60.18％), in which rate of drug resistance to meropenem and imipenem were 1.47％ and 2.94％ respectively. There were 41 strains carried CTX-M drug resistance genotype, which mainly were type CTX-M-14 and type CTX-M-15, 18 strains each. Compared with neutral environment of the pH value at 6 or 6.5, the rate of Escherichia coli resistant to cefuroxime, cefotaxime, ceftazidime and ceftriaxone had no difference (P>0.05), while the resistance to cefepime was significantly increased when pH was 6.0 (P<0.01). With the pH value at 8 or 8.5, the rate of Escherichia coli resistance to ceftazidime and cefepime was significantly decreased, and with the pH value at 8.5 the rate of Escherichia coli resistance to cefotaxime also significantly decreased (P<0.01). Conclusions The rate of ESBL-producing Escherichia coli resistance to carbapenem antibiotic is low. The rate of Escherichia coli carrying CTX-M drug resistance genotype is high with CTX-M-14 and CTX-M-15 being the most prevalent genotypes. Properly alkalization of urine may contribute to the treatment of CTX-M resistant Escherichia coli in children with urinary tract infection.

Prevalence of Fecal Carriage of CTX-M-15 Beta-Lactamase-Producing Escherichia coli in Healthy Children from a Rural Andean Village in Venezuela

OBJECTIVES: Antimicrobial resistant extended-spectrum-β-lactamase-producing Enterobacteriaceae (ESBL-PE) have been shown to be present in healthy communities. This study examined healthy children from the rural Andean village of Llano del Hato, Mérida, Venezuela, who have had little or no antibiotic exposure to determine the prevalence of fecal carriage of ESBL-producing Escherichia coli (ESBL-EC). METHODS: A total of 78 fecal samples were collected in healthy children aged from 1 to 5 years. ESBL-EC were selected in MacConkey agar plates with cefotaxime and further confirmed by the VITEK 2 system. ESBL were phenotypically detected and presence of bla genes and their variants were confirmed by molecular assays. Determination of phylogenetic groups was performed by PCR amplification. Risk factors associated with fecal carriage of ESBL-EC-positive isolates were analyzed using standard statistical methods. RESULTS: Of the 78 children studied, 27 (34.6%) carried ESBL-EC. All strains harbored the bla(CTX-M-15) allele. Of these, 8 were co-producers of bla(TEM-1), bla(TEM-5), bla(SHV-5) or bla(SHV-12). Co-resistance to aminoglycosides and/or fluoroquinolones was observed in 9 strains. 51.9% of ESBL-EC isolates were classified within phylogroup A. A significant, positive correlation was found between age (≥2.5 – ≤5 years), food consumption patterns and ESBL-EC fecal carriage. CONCLUSION: This is the first study describing the high prevalence of fecal carriage of ESBL-EC expressing CTX-M-15- among very young, healthy children from a rural Andean village in Venezuela with scarce antibiotic exposure, underlining the importance of this population as a reservoir.

Forecasting incidence of extended spectrum β-lactamases-producing Escherichia coli by multiple seasonal ARIMA model / 预防医学

Objective To predict monthly incidents of extended spectrum β-Lactamases (ESBLs)-producing Escherichia coli in Zhejiang Hospital by establishing multiple seasonal autoregressive integrated moving average (ARIMA) model, so as to provide scientific evidence for reducing the incidents of nosocomial infection of ESBLs producing Escherichia coli. Methods Multiple seasonal ARIMA model was established by monthly records of ESBLs producing Escherichia coli from 2010 to 2016 in Zhejiang hospital. Monthly incidents of ESBLs producing Escherichia coli from 2017 to February 2018 were used to verify the predicted result. The predictions were evaluated by models of mean absolute percent error (MAPE) and bayesian information criterion (BIC) . Results The optional model for the monthly incidence from 2010 to 2016 was ARIMA (0, 1, 1) (0, 1, 1)12. The MAPE was 14.76, BIC was 2.01, and the Ljung-Box statistics value Q was 16.79 (P=0.40) . These parameters suggested a good model fitting. The average relative error between the predictive value and the actual value of the monthly incidents ESBLs producing Escherichia coli from 2017 to February 2018 was 14.08%.The actual values were within the 95% confidence interval. Conclusion The multiple seasonal ARIMA model of ARIMA (0, 1, 1) (0, 1, 1 )12 fits and can be used for short-term prediction and dynamic analysis of the incidents of ESBLs producing Escherichia coli in Zhejiang Hospital.

Study on the resistance genes of carbapenem-resistant Enterobacteriaceae collected from 5 hospitals in Northeast China / 中华传染病杂志

Objective To investigate the antibiotic resistance and resistance genes of carbapenem-resistant Enterobacteriaceaes (CRE) isolated from 5 hospitals in Northeast China.Methods This study collected 85 CRE isolates during January 2013 to June 2015 from five hospitals in Northeast China.Drug sensitivities of 14 antimicrobial agents were determined by the broth microdilution method.The phenotypes of carbapenemases were screened by modified Hodge test and EDTA test respectively.The genotypes of carbapenemases and other extended spectrum β-lactamases (ESBL) were detected by PCR gene amplification and DNA sequencing method.Using the PCR result as gold standard, the performances of other two carbapenemase detection methods were evaluated.Results Among the 85 CRE strains collected in this study, Klebsiella pneumoniae was the most frequently isolated species (61/85,71.8%).The results of antimicrobial agent sensitivity showed that the 85 CRE strains had resistance rate of cephalosporin and β-lactams/enzyme inhibitor (piperacillin-tazobactam) over 80.0%.The resistance rate of carbapenem was high, with ertapenem 100.0% (85/85), meropenem 65.9% (56/85), imipenem 71.8% (61/85).There were 36 isolates resistant to both meropenem and imipenem.For fluoroquinolones, the resistance rates of levofloxacin and ciprofloxacin were 72.9% (62/85) and 65.9% (56/85), respectively.The resistance rate to fosfomycin and amikacin were 65.0% (55/85) and 54.1% (46/85), respectively.The resistance rate of colistin (21.2%, 18/85) and tigecycline (20.5%, 17/85) were low.Forty-nine strains were modified Hodge test positive and 12 strains were EDTA test positive.By PCR gene amplification and DNA sequencing method, 64 strains carried carbapenemase-encoding genes, of which KPC-2 was the main type (53/85, 62.4%), followed by IMP-4 (10/85, 11.8%), NDM-5 (7/85, 8.2%) and NDM-6 (1/85, 1.2%).At the same time, 85 CRE isolates had the ESBL gene detection and 47 isolates were CTX-M type ESBLs (47/85, 55.3%), with no TEM or SHV type.Conclusions Klebsiella pneumoniae is the majority of CRE strains from 5 large hospitals in Northeastern China.The CRE strains are resistant to most of antimicrobials.Most carbapenemases-producing isolates have the KPC-2 type.Nearly half of the carbapenemase-producing strains also carry ESBL genes, which makes the resistance mechanisms more complicated.

Multidrug Resistance Mechanisms of Carbapenem Resistant Klebsiella pneumoniae Strains Isolated in Chongqing, China

BACKGROUND: Carbapenem-resistant Klebsiella pneumoniae (CRKP) is considered a serious global threat. However, little is known regarding the multidrug resistance (MDR) mechanisms of CRKP. This study investigated the phenotypes and MDR mechanisms of CRKP and identified their clonal characteristics. METHODS: PCR and sequencing were utilized to identify antibiotic resistance determinants. Integron gene cassette arrays were determined by restriction fragment length polymorphism (RFLP) analysis. Multi-locus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE) were used for epidemiological analysis. Plasmids were typed by using a PCR-based replicon typing and analyzed by conjugation and transformation assays. RESULTS: Seventy-eight strains were identified as resistant to at least one carbapenem; these CRKP strains had a high prevalence rate (38.5%, 30/78) of carbapenemase producers. Additionally, most isolates harbored MDR genes, including Extended spectrum β-lactamases (ESBLs), AmpC, and quinolone and aminoglycoside resistance genes. Loss of porin genes was observed, and Class 1 integron was detected in 66.7% of the investigated isolates. PFGE and MLST results excluded the occurrence of clonal dissemination among these isolates. CONCLUSIONS: A high prevalence of NDM-1 genes encoding carbapenem resistance determinants was demonstrated among the K. pneumoniae isolates. Importantly, this is the first report of bla(NDM-1) carriage in a K. pneumoniae ST1383 clone in China and of a MDR CRKP isolate co-harboring bla(NDM-1), bla(KPC-2), bla(CTX-M), bla(SHV), acc(6′)-Ib, rmtB, qnrB, and acc(6′)-Ib-cr.

Epidemiology and risk factors for community-acquired blood stream infection caused by extended spectrum β-lactamases-producing Escherichia coli and Klebsiella pneumonia strains / 中华微生物学和免疫学杂志

Objective To investigate the incidences, risk factors, genotypes and epidemiology of community-acquired blood stream infection caused by extended spectrum β-lactamases (ESBLs)-producing Escherichia coli and Klebsiella pneumonia strains and to analyze the sensitivity of those ESBLs producing strains to commonly used antibiotics. Methods Forty-two patients who were diagnosed with community-ac-quired blood stream infection caused by Escherichia coli or Klebsiella pneumonia strains in Sichuan Provincial People′s Hospital were recruited in this study. Disc diffusion method was used for the phenotypic confirmato-ry test of ESBLs. Agar dilution method was performed to measure the antimicrobial susceptibility of the ESBLs-producing strains to 13 clinically commonly used antibiotics. Genotypes of the ESBLs-producing strains were identified by polymerase chain reaction (PCR). Multilocus sequence typing (MLST) was used to analyze the epidemiology of ESBLs-producing strains. Logistic regression analysis was performed to analyze the risk factors for community-acquired blood stream infection. Results The ESBLs-producing Escherichia coli strains accounted for 56. 3% (18 / 32) and the ESBLs-producing Klebsiella pneumoniae strains accounted for 20% (2 / 10). All of the 20 ESBLs-producing strains were sensitive to imipenem, meropenem, ertapen-em, nitrofurantoin and moxalactam. The ESBLs-producing strains sensitive to amikacin, piperacillin-tazobactam and fosfomycin accounted for 95% , 90% and 85% , respectively. Drug resistance rates of the 20 strains to cefotaxime, levofloxacin, ciprofloxacin and cefepime were relatively high accounting for 100% , 80% , 80% and 75% , respectively. Among the 20 ESBLs-producing strains, 7 strains only carried the CTM gene, while the other 13 strains were all positive for two genotypes of ESBLs, mainly identified as TEM+CTM-M-14 and TEM+CTM-15 genotypes. The 18 Escherichia coli strains were classified into 10 ST types, most of which were ST131 type, followed by ST10 and ST38 types. This study indicated that malignant tumor might be a possible risk factor. Conclusion The prevalence of community-acquired blood stream infection caused by ESBLs-producing Escherichia coli strains was becoming increasingly serious. Malignant tumor might be the risk factor associated with the producing of ESBLs in Escherichia coli and Klebsiella pneumonia strains. TEM+CTX-M-14 was the predominant genotype of ESBLs-producing strains and the prevalent clone was ST131 type. Carbapenems and enzyme inhibitor compounds were ideal drugs for the treatment of commu-nity-acquired blood stream infection caused by ESBLs-producing Escherichia coli and Klebsiella pneumonia strains. This study was limited by the small sample size. Therefore, it is necessary to conduct further resear-ches based on a large number of samples.

ClassⅠ integron and its correlation with genes coding forESBLs in ESBLs-producing Escherichia coli from chil-dren / 临床儿科杂志

ObjectiveTo study the correlation with Genes Coding forESBLs and ClassⅠIntegron in ESBLs-producing Escherichia coli from children.MethodsPCR was used for gene typing detection of 100 strains of ESBLs-producingEsche-richia colistrains. While detection of class I integrase gene in the 100 strains ESBLs-producingEscherichia coli and 100 strains of non-ESBLs producingEscherichia coli were separately performed by PCR. It provides the solid base not only to reveal the relationship between class I integron and drug resistance, but also the relationship between class I integron and ESBLs-producing. ResultsThe most frequently genotyping from ESBLs-producingEscherichia coli in children isCTX-M (84%), followed by TEM-1(63%). The predominant distribution of genotype in ESBL- producing strains isTEM-1 +CTX-M (45%), followed by CTX-M (34%). Class I integrase gene detected in ESBLs- producing and non- ESBLs producing strain were 100 cases (100%) and 25 cases (25%) separately, the difference was statistically signiifcant (P<0.05); drug resistance in class I integron positive strains were signiifcantly higher than in class I integron negative strains, especially in Ciprolfoxacin, Levolfoxacin, and Amino-glycoside (86.4%, 88%, and 80%).ConclusionsThe distribution of Class I integron in ESBLs-producingEscherichia coli is signiifcantly higher than that in non-ESBLs-producing strains, It is rational that Class I integron highly correlate with strong drug resistance in ESBLs-producing strains.

Molecular characterization and in vitro susceptibilities of β-lactamase producing Escherichia coli, Klebsiella species, Acinetobacter baumannii, Pseudomonas aeruginosa and Staphylococcus aureus to CSE1034 and other β-lactams

OBJECTIVE@#To study the prevalence of extended-spectrum β-lactamases (ESBLs) among 663 clinical isolates obtained from various parts of India and to study the occurrence of different variants of ESBLs among these isolates.@*METHODS@#Phenotypic characterization and susceptibility studies were performed according to the methods described in Clinical and Laboratory Standards Institute guidelines. The occurrence of ESBL variants was analyzed with PCR using the previously reported primers.@*RESULTS@#Among the six hundred sixty three isolates, the identified isolates were Acinetobacter baumannii (72), Escherichia coli (218), Klebsiella pneumoniae (30), Klebsiella oxytoca (63), Pseudomonas aeruginosa (264) and Staphylococcus aureus (16). PCR results revealed that approximately 89.0% of Pseudomonas aeruginosa isolates were positive for ESBL followed by Escherichia coli (85.3%), Klebsiella pneumoniae (76.6%), Klebsiella oxytoca (73.0%), Acinetobacter baumannii (72.2%) and Staphylococcus aureus (31.2%). The overall prevalence of ESBL was 82.5%. The presence of TEM type ESBLs were the predominant (in 186 isolates), followed by SHV (138), OXA (92), CTX-M (65), AmpC (33), KPC (28) and blaZ (5). Of the drugs involved in the study, CSE1034 was found to be the most efficacious against all of ESBL positive clinical isolates showing susceptibility approximately 95.7% with minimal inhibitory concentration values between 0.125 and 8.000 μg/mL for all strains tested. The susceptibilities of penems (meropenem and imipenem and cilastatin) ranged between 83% and 93% for all the isolates. The susceptibilities of other drugs like piperacillin and tazobactam, amoxicillin and clavulanic acid, cefoperazone and sulbactam were <45% for all the isolates.@*CONCLUSIONS@#Results of the present study indicated that majority of the isolates was susceptible to CSE1034 and it could be a potent antibacterial agent for the treatment of severe bacterial infections caused by such organisms.

The expression of ESBLs genes in Escherichia coli isolates induced by β-lactam antibiotics and inhibited by histidine kinase inhibitors / 中华微生物学和免疫学杂志

Objective To investigate the genotypes of extended spectrum β-lactamases (ESBLs) and their carrying modes in Escherichia coli (E.coli) isolates,and to analyze the mechanism of protein phosphorylation and ESBLs gene expression induced by β-lactam antibiotics or inhibited by histidine kinase inhibitors.Methods The predominant genotypes of ESBLs (KPC,TEM,SHV and CTX-M) and their carrying modes were identified by PCR and sequencing analysis.E-test and micro-tube dilution method were applied to measure minimal inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs).Immobilized metal ion affinity chromatography,bacterial protein phosphorylation detection kit and real-time fluorescent quantitation RT-PCR were performed to analyze the enhancing effects of 1/4 MIC penicillin or cefotaxime or the inhibitory effects of histidine kinase inhibitors (closantel,bromized or iodized methylimidazol) on protein phosphorylation and the expression of ESBLs at mRNA level in E.coli isolates.Results In 183 β-lactam antibiotics-resistant E.coli isolates,TEM and CTX-M genes (83.1％ and 77.1％) were highly expressed than other two ESBLs genes with a prevalent carrying mode of coexisting (65.0％) (P＜0.05).Penicillin or cefotaxime at 1/4 MIC induced the protein phosphorylation and promoted the expression of TEM,SHV and CTX-M at mRNA level (P＜0.05).Closantel (200 μmol),bromized methylimidazol (2 or 10 μmol) or iodized methylimidazol (20 or 50 μmol) could neither kill E.coli isolates nor inhibit their growth,but could inhibit the protein phosphorylation induced by above mentioned antibiotics and enhance the expression of ESBLs at mRNA level (P＜0.05).Moreover,the susceptibility of antibioticresistant E.coli strains to penicillin and cefotaxime were increased (P＜0.05).Conclusion TEM and CTX-M were the predominant genotypes of ESBLs carried by β-lactam antibiotics-resistant E.coli strains isolated from Zhejiang province,which were mostly found in a TEM plus CTX-M carrying mode.Sublethal dose of β-lactam antibiotics could up-regulate the expression of ESBLs genes in E.coli isolates via TCSS,but it could be inhibited by histidine kinase inhibitors.

Characteristics of clinical Shigella isolates por ducing the extended -spectrum and AmpCβ-lactamases / 中华微生物学和免疫学杂志

Objective To investigate the phenotypes and genotypes of extended -spectrum β-lacta-mases (ESBLs) and AmpC β-lactamases produced by cefoxitin-resistant Shigella strains isolated from Zhe-jiang province and the virulence of those strains .Methods Kirby-Bauer antibiotic testing was performed to screen cefoxitin-resistant strains from 356 Shigella isolates.The serotypes of the cefoxitin-resistant strains were detected .The phenotypes of ESBLs and AmpC β-lactamases from cefoxitin-resistant strains were detec-ted by ESBLs confirmatory test and AmpC-three-dimensional test ,respectively .The genotypes of ESBLs and AmpC β-lactamases were analyzed by PCR and sequence analysis .The virulence genes ( virA, ial, iapH, set1A, set1B and sen) in the cefoxitin-resistant strains were screened by PCR .Results Eight cefoxitin-re-sistant strains were identified from 356 Shigella isolates.Among them,six strains were identified as Shigella flexneri (S.fleaneri) strain (four F2a,one F2b and one F2c),and the rest were identified as Shigella sonnie (S.sonnei) strain.Among all eight cefoxitin-resistant strains,five strains showed positive results for ESBLs confirmatory test and two strains showed positive results for AmpC-three-dimensional test .Seven out of the eight strains harbor ESBLs genes (CTX-M-14,15,57 and/or OXA-30),two of which were positive for AmpC genes (DHA-1 and CMY-2).Five out of the eight cefoxitin-resistant strains carried all of the six tested viru-lence genes,while the other three strains possessed four virulence genes except for set1A and set1B.The two strains producing both ESBLs and AmpC β-lactamases were susceptible only to imipenem .Conclusion ESBLs positive isolates are prevalent strains of cefoxitin-resistant Shigella with potential high virulence .Some of them also produce AmpC β-lactamases ,and the DHA-1 type of AmpCβ-lactamase is identified for the first time in China .

Molecular characterization and in vitro susceptibilities of β-lactamase producing Escherichia coli, Klebsiella species, Acinetobacter baumannii, Pseudomonas aeruginosa and Staphylococcus aureus to CSE1034 and other β-lactams

Objective: To study the prevalence of extended-spectrum β-lactamases (ESBLs) among 663 clinical isolates obtained from various parts of India and to study the occurrence of different variants of ESBLs among these isolates. Methods: Phenotypic characterization and susceptibility studies were performed according to the methods described in Clinical and Laboratory Standards Institute guidelines. The occurrence of ESBL variants was analyzed with PCR using the previously reported primers. Results: Among the six hundred sixty three isolates, the identified isolates were Acinetobacter baumannii (72), Escherichia coli (218), Klebsiella pneumoniae (30), Klebsiella oxytoca (63), Pseudomonas aeruginosa (264) and Staphylococcus aureus (16). PCR results revealed that approximately 89.0% of Pseudomonas aeruginosa isolates were positive for ESBL followed by Escherichia coli (85.3%), Klebsiella pneumoniae (76.6%), Klebsiella oxytoca (73.0%), Acinetobacter baumannii (72.2%) and Staphylococcus aureus (31.2%). The overall prevalence of ESBL was 82.5%. The presence of TEM type ESBLs were the predominant (in 186 isolates), followed by SHV (138), OXA (92), CTX-M (65), AmpC (33), KPC (28) and blaZ (5). Of the drugs involved in the study, CSE1034 was found to be the most efficacious against all of ESBL positive clinical isolates showing susceptibility approximately 95.7% with minimal inhibitory concentration values between 0.125 and 8.000 μg/mL for all strains tested. The susceptibilities of penems (meropenem and imipenem and cilastatin) ranged between 83% and 93% for all the isolates. The susceptibilities of other drugs like piperacillin and tazobactam, amoxicillin and clavulanic acid, cefoperazone and sulbactam were <45% for all the isolates. Conclusions: Results of the present study indicated that majority of the isolates was susceptible to CSE1034 and it could be a potent antibacterial agent for the treatment of severe bacterial infections caused by such organisms.

Reversal of multiple drug resistance in Escherichia coli by blocking CTX-M through antisense phosphothioate oligodeoxynucleotides / 中华微生物学和免疫学杂志

Objective To investigate the effects of antisense phosphothioate oligodeoxynucleotides (AS-ODNs) W086 on drug-resistant gene CTX-M expression in Escherichia coli producing extended-spectrum β-lactamases(ESBLs).Methods AS-ODNs liposome was introduced into the purpose bacteria B052.The total colony forming unit(CFU) was counted.The bacteria growth curve was drawn by microplate reader.The inhibition effects of AS-ODNs on the expressions of drug-resistant gene CTX-M were observed by RT-PCR in B052.The minimal inhibitory concentration(MIC)was determined by fluid dilution method.Results significant growth inhibition of cells treated with W086 was observed as compared with those in cells in control treated bacteria.The number of B052 colonies significantly decreased in all W086 treated groups in a concentration dependent manner (P ＜ 0.05),while CFU of B052 was not influenced in simple liposome group,simple W086 group and controlled chain group.The expression of CTX-M was selectively inhibited.Conclusion Efficiently and specificly blocking expression of CTX-M mRNA,AS-ODNs reverses the multiple drug resistance of B052.It indicates that AS-ODNs provides a new viable strategy to reverse antibiotic resistance problem.

Analysis on the detection and antibiotic resistance of extended-spectrum β-lactamases-producing Klebsiella pneumoniae and Escherichia coliisolated from patients in Intensive Care Unit / 中国综合临床

Objective To analyse the detection rates and antibiotic resistance of extended-spectrum β-lactamases (ESBLs) producing Klebsiella pneumonia and Escherichia coli in Intensive Care Unit (ICU) and to guide the clinical administration of treatment Methods Klebsiella pneumonia and Escherichia coli collected from clinical samples from January 2008 to December 2010 were tested by Phenotypic Confirmatory Test and confirmed by the method advised by NCCLs and drug-sensitivity was tested with K-B. Results Among the isolated 90 samples,49 strains were considered ESBLs-producing bacteria (54.4%) .with 52. 5% (31/59)of Klebsiella pneumonia and 58. 1% (18/31) of Escherichia coli respectively; with the specimens of respiratory system having the highest rate of 75. 5% (37/49). ESBLs producing bacteria were highly resistant to penicillins and cephalosporins, multi drug resistant to aminoglycosides and quinolones; low to piperacillin/tazobactam,cefoperazone/sulbactam,cefoxitin and amikacin; and all sensitive to imipenem. When compared to non-ESBLs producing strains, the rates of antibiotic resistance of the producing ESBLs strains were significantly higher. Conclusion The test results showed that the isolation rates of ESBLs-producing Klebsiella pneumoniae and Escherichia coli in ICU were high,which had high resistance to most antimicrobial agents,and the resistance was multiple. Imipenem could be the best choice to control the infection due to ESBLs-producing organisms. Timely detection of ESBLs producing bacteria and drug resistance is essential to guide clinical antibiotic using in ICU.

Characterization of antibiotic resistance and carbapenemase-producing in carbapenem no-susceptibility Enterobacteriaceae from pediatric patients / 中华微生物学和免疫学杂志

Objective To analyze the antibiotic resistance of the carbapenem no-susceptibility Enterobacteriaceae isolated from pediatric patients and the resistant genes of carbapenemase-producing.Methods In all,46 carbapenem no-susceptibility Enterobacteriaceae strains were isolated from patients at Beijing Children's Hospital between January 2008 and December 2010.Agar dilution method recommended by the Clinical and Laboratory Standards Institute was used to examine the minimum inhibitory concentrations (MICs) of 14 antimicrobial agents.Phenotypic testing for carbapenemase-producing was conducted using Hodge test and double-disk synergy test.PCR was used to detect the expression of the carbapenemase-related genes KPC,GES,IMI/NMC-A,SME,IMP,VIM,GIM,SPM,SIM and OXA.WHONET5.6 was used to perform resistance analysis.Results Among 46 carbapenem no-susceptibility Enterobacteriaceae strains,26 (56.5％) were Klebsiella pneumoniae strains,13(28.3％ ) were Enterobacter cloacae and 7( 15.2％ ) were Escherichia coli.The rates of imipenem and meropenem no-susceptibility Klebsiella pneumoniae were 69.2％ and 80.8％,Enterobacter cloacae were 76.9％ and 100％ and Escherichia coli were 85.7％ and 100％,respectively.40(87.0％ ) strains were positive of Hodge test.41 (89.1％) strains were positive of doubledisk synergy test.38 (82.6％) were positive for the IMP genotype.The carbapenemase-related genes were not found in other 8 strains.Conclusion The prevalence of carbapenem no-susceptibility Enterobacteriaceae strains in Klebsiella pneumoniae isolates is relatively high in children.Resistance to imipenem was lower than that to meropenem from Klebsiella pneumoniae,Enterobacter cloacae and Escherichia coli strains.Many carbapenem no-susceptibility Enterobacteriaceae isolated from pediatric patients carry the blaIMP gene.No the KPC gene was found.

Progress of Moraxella Catarrhalis / 国际儿科学杂志

Moraxella Catarrhalis emerged as the third cause of respiratory tract infection in children.Over 90% of the Moraxella Catarrhalis strains isolated currently produced by β-lactamases positive.Moraxella Catarrhalis resist to Ampicillin because of the β-lactamases,such as the BRO-1 type,BRO-2 type and BRO-3 type.The BRO genes appeared to be located on the chromosome and be coded.Twenty-one new mutations were found in the putative promoter region of the BRO genes.

The mechanism of AmpC β-lactamase change from inducible type to constitutive type / 复旦学报（医学版）

Objective To investigate the influence of plasmid spread and ampD mutation to Enterobacter cloacae that leads to the AmpC β-lactamase change from inducible type to constitutive type. Methods The Enterobacter cloacae were isolated from the patients with nosocomial infection. The inducible type isolations and their constitutive type changers were put into the same group. The plasmid ampC gene and chromatin ampD gene in pairs in each group were amplified, sequenced and compared. Results Of 195 patients infected by Enterobacter cloacae of inducible type, 25 (12.82%) were changed to the ones of constitutive high type. In these 25 changed groups, 10 were caused by plasmid spread, 10 by ampD mutation, 1 by both, and 4 by neither. Twelve changed constitutive type strains had ampD significant mutations, in which 7 were frame-shift mutations and 5 were spot mutations. Conclusions The change ratio of Enterobacter cloacae from inducible type to constitutive type is rather high. Both plasmid spread and ampD mutation are possibly the mechanism of such change. Plasmid mediated AmpC β-lactamase spreads among different species and interregionally. The mutation rate of chromatin ampD gene is also higher than the natural mutation rate. These two mechanisms should be considered in clinical treatment.

Genotype and drug resistance analysis of extended-spectrum beta-lactamases-producing Shigella in pediatric patients / 中华微生物学和免疫学杂志

Objective To investigate the genotype and drug resistance of extended-spectrum beta-lac-tamases(ESBLs) -producing Shigella in pediatric patients.Methods A total of 59 strains of Shigella were isolated from stool specimens of hospitalized children with shigellosis in Beijing Children's Hospital from January 2004 to December 2008.Phenotypic confirmatory test,which is based on Clinical and Laboratory Standards Institute(CLSI),was used to detect the ESBLs-producing strains.Agar dilution method was used to determine the minimal inhibitory concentration (MIC).PCR amplification was performed for ESBLs producers to determine the genotype.PCR product was sequenced and then analyzed to confirm the subtype of ESBLs.Results Of the 59 isolates,21 (35.6%) strains were identified as ESBLs producers.The 21 strains of ESBLs-producing Shigella all carried the genes of CTX-M as shown by PCR,and CTX-M-1,CTX-M-9 accounted for 6,15,respectively.Among the 21 CTX-M producers,there were 4 strains accompanied by TEM-type and 6 strains accompanied by OXA-type.Nucleotide sequence analysis showed that there were CTX-M-3 (n = 1),CTX-M-15 (n = 2),CTX-M-57(n =3) of the 6 CTX-M-1-producing isolates.The subtypes of CTX-M-9,TEM,OXA were all CTX-M-14,TEM-1,OXA-1,respectively.The sensitive drugs to ESBLs producers were imipenem,meropenem,piperacillin/tazobactam,cefoperazone/sulbactam and cefoxitin,with resistance rate all less than 15%.The resistance to ceftazidime was remarkably variable among different CTX-M producers.Conclusion The prevalence of ESBLsproducing Shigella is in a high level in pediatric patients in this area.The genotypes of ESBLs are all CTX-M.Most of them are CTX-M-14,but some are CTX-M-3,CTX-M-15 and CTX-M-57.Most ESBLs-producing strains are multidrug resistant.Carbopenems should be the first choice for ESBLs producers.