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.

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.

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.

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.

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.

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.

Extended-spectrum β-lactamase and AmpC β-lactamase Production among Gram-negative Bacilli Isolates Obtained from Urinary Tract Infections and Wound Infections.

Extended-spectrum β-lactamases (ESBLs) and AmpC β-lactamases continue to be a major problem in healthcare settings. Due to the scarcity of information regarding the antibiotic susceptibility patterns particularly from urinary tract infections (UTIs) and wound infections, the current study was carried out to assist the clinicians to prescribe appropriate antibiotics against gram-negative clinical isolates. In the current study, urine (n = 620) and pus (n = 228) samples were collected from different sites (at various clinical departments) and subjected to direct microscopic examination, culture and antibiotic susceptibility testing (AST). In the AST testings, the isolates that exhibited reduced zone of inhibition to one or more of the antibiotics such as cefotaxime (≤27 mm), ceftriaxone (≤25 mm), ceftazidime (≤22 mm), cefpodoxime (≤17 mm) and aztreonam (≤27 mm) were considered as potential ESBL producers and the ESBL production was confirmed using phenotypic screening test (doubledisk synergy test) and phenotypic confirmatory test (combined-disk test). However, isolates showing resistance or decreased sensitivity to cefoxitin, cefotaxime, ceftriaxone, ceftazidime, cefpodoxime or aztreonam and sensitive to cefepime were considered as a screen positive AmpC producer and subjected to AmpC disk tests. The current study concluded that 72.41% and 21.76% of ESBL and AmpC producers were detected, respectively in our hospital. It was also observed that the double-disk synergy and combined-disk tests were equally effective for ESBL detection. Further, AmpC disk test is simple, easy to perform and interpret, requiring less expertise for the rapid detection of AmpC isolates.

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.

Incidence of neonatal sepsis in tertiary care hospital: An overview.

Background: Neonatal sepsis is one of the commonest causes of neonatal mortality in the developing world. Aims & Objective: To determine the bacteriological profile of neonatal septicaemia, their antibacterial susceptibility pattern (AST) and production of extended spectrun β-lactamase (ESBL) by gram negative bacteria. Material and Methods: Blood culture specimens were collected from 238 neonates. Identification of organisms, their AST, methicillin resistant Staphylococcus aureus (MRSA) and ESBL detection was done. Results: Gram negative bacteria were more frequently isolated than gram positive bacteria. The gram positive bacteria were highly resistant to penicillin. Vancomycin and amoxyclav exhibited good activity against both Staphylococcus aureus and coagulase negative Staphylococcus. Gram negative bacteria also exhibited high resistance to the commonly prescribed group of drugs such as penicillins, cephalosporins and aminoglycosides. Out of the total 16 isolates of S. aureus, 31.25% were MRSA. ESBL production was seen in 52.9% of Escherichia coli and 50% of Klebsiella pneumoniae. Conclusion: E. coli and S. aureus were the most common bacteria associated with neonatal sepsis. Gram negative bacteria were isolated predominantly and many of them were resistant to several groups of drugs. Also high resistance was seen to third generation cephalosporins in case of E. coli and K. pneumoniae due to ESBL production.

Incidence of blaNDM-1 gene in Escherichia coli isolates at a tertiary care referral hospital in Northeast India.

Purpose: Increasing reports on New Delhi metallo-β-lactamase-1 (NDM-1) producing Escherichia coli constitute a serious threat to global health since it is found to be highly resistant to most of the currently available antibiotics including carbapenems. This study has been performed to find out the incidence blaNDM-1 in E. coli isolates recovered from the various clinical samples at a tertiary care referral hospital in Northeast India. Materials and Methods: A total of 270 non-duplicated E. coli isolates were recovered from the various clinical samples at a tertiary care referral hospital in Northeast India. All isolates with reduced susceptibility to meropenem or ertapenem (diameter of zones of inhibition, ≤21 mm) were further phenotypically confirmed for carbapenemase production by modified Hodge test. All screened isolates were also subjected to the polymerase chain reaction detection of blaNDM-1 gene and additional bla genes coding for transmission electron microscopy, SHV, CTX-M, and AmpC. Results: Out of 270 E. coli isolates, 14 were screened for carbapenemase production on the basis of their reduced susceptibility to meropenem or ertapenem. All screened isolates were found to be positive for blaNDM-1 . Each of the blaNDM-1 possessing isolate was also positive for two or more additional bla genes, such as blaTEM , blaCTX-M and blaAmpC . Phylogenetic analysis showed very less variation in blaNDM-1 gene with respect to blaNDM-1 possessing E. coli isolates from other parts of India and abroad. Conclusions: Our findings highlight the incidence of blaNDM-1 in E. coli isolates with a reduced susceptibility to meropenem or ertapenem.

Detection of extended spectrum β-lactamase among gram negative clinical isolates from a tertiary care hospital in South India.

Background: The β lactamase enzymes produced by the organisms break down the structural beta-lactam ring of β lactam antibiotics. Many genera of gram negative bacteria possess a naturally occurring, chromosomally mediated β lactamase and also some are plasmid mediated β lactamases. The objective of the study was to detect extended spectrum β lactamases among gram negative clinical isolates. Methods: 200 clinical were subjected to routine disc diffusion technique and zone diameter of ≤27mm for Cefotaxime and ≤22mm for Ceftazidime or ≤25mm for Ceftriaxone were included in this study. The strains are subjected to double disc synergy test. Results: Of 200 samples, 174 yielded organisms belonging to enterobacteriaceae and 26 yielded growth of nonfermenters. Out of 174 members of enterobacteriaceae family, 122 were E. coli, 36 Klebsiella spp, 8 Proteus spp, 5 Enterobacter spp and 3 Citrobacter spp. Out of 26 nonfermenters, 18 were Pseudomonas spp and 8 were Acinetobacter. Conclusions: In the present study prevalence of ESBL was 23.3%, the high prevalence may be due to irrational use of third generation cephalosporins in both the hospital and community.

Detection of plasmid-mediated AmpC β-lactamase in Escherichia coli and Klebsiella pneumoniae.

Background: Detecting plasmid-mediated AmpC (pAmpC) β-lactamase-producing organism is important for optimal infection control and providing accurate and effective treatment option for physicians. Objectives: The aim of this study was to investigate the prevalence of pAmpC β-lactamase and compare the results of boronic acid (BA) disk test with other phenotypic tests detecting AmpC positive isolates. Materials and Methods: A total of 273 clinical isolates of Klebsiella pneumoniae (n: 82) and Escherichia coli (n: 191) were analysed. The presence of pAmpC β-lactamase was determined by BA disk test, cefoxitin (FOX) screening test, modified three dimensional test (M3DT), and multiplex polymerase chain reaction (PCR). Pulsed-field gel electrophoresis was performed to evaluate the genetic similarities between isolates. To detect extended spectrum β-lactamases (ESBL) in the presence of AmpC β-lactamase, ESBL confirmation test was carried out with and without BA solution. Results: Of the 273 strains tested, 127 strains were found FOX resistant, 114 were positive by M3DT, 108 were positive in BA disk test, and the multiplex PCR detected 24 pAmpC β-lactamase-positive isolate. The prevalence of AmpC-producing strains was 10.9% in E. coli and 3.6% in K. pneumoniae in the tested population by PCR. CIT and MOX group genes were predominant type in these strains. Conclusion: These results emphasize that clinical laboratories should consider testing the presence of pAmpC enzymes particularly in FOX-resistant isolates, and BA disk test will improve detection of this emerging resistance phenotype.

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.

First detection of TEM-116 extended-spectrum β-lactamase in a Providencia stuartii isolate from a Tunisian hospital.

Purpose: To study the resistance to third-generation cephalosporins in Providencia stuartii strain isolated from hospitalized patient in Tunisia and to identify the responsible genes Materials and Methods: This strain was analysed by PCR and sequencing to identify the genes responsible for the β-lactamase resistance phenotypes. The transferability of the phenotypes was tested by conjugation to Escherichia coli J53. The isoelectric point was determinate by isoelectrofocalisation. Results: This resistance was carried by a 60 kb plasmid that encoded a β-lactamase with a pI of 5.4. This β-lactamase revealed identity with the blaTEM-1 gene encoding the TEM-1 β-lactamase, except for a replacement of the Val residue at position 84 by Ile, and the Ala residue at position 184 by Val. These two mutations were encountered in TEM-116 β-lactamase. Conclusion: This study demonstrates the first description of TEM-116 in the P. stuartii species in the world and the first one in a Tunisian hospital.

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.