Emergence of novel variants of gyrA, parC, qnrS genes in multi-drug resistant Klebsiella caused pneumonia / 中华流行病学杂志

Objective To investigate the resistant mechanism of quinolones on multi-drug resistant Klebsiella caused pneumonia(MDR-KPN).Methods From August 2008 to May 2010,47 strains of MDR-KPN were collected from 6 hospitals in Hangzhou and Huzhou in Zhejiang province in China.Drug target genes to quinolones (gyrA,parC) and quinolone-resistance genes mediated by mobile genetic elements [qnrA,qnrB,qnrS,aac (6')-Ⅰ b-cr,qepA] were analyzed by PCR and verified by DNA sequencing.Results Positive results were found in 47 strains of MDR-KPN,43 strains (91.5％) of gyrA mutation,40 strains(85.1％) ofparC mutation,3 strains (6.4％) of qnrB2,1 strain (2.1％) ofqnrB 4,8 strains (17.0％) ofqnrS 1,5 strains (10.6％) of qnrS 4,2 strains (4.3％)of aac (6')-Ⅰ b-cr respectively.Moreover,5 novel variants of gyrA (GenBank accession number:JN811952,JN811953,JN811954,JN811955,JN811956),5 novel variants of parC (GenBank accession number:JN817432,JN817433,JN817434,JN817435,JN817436)were also identified.In addition,qnrS4 (GenBank accession number:JN836269) appeared to be the novel variants of qnrS.Conclusion Quinolone-resistance-determining region played a key role on the resistance to quinolones in this group of MDR-KPN,and quinolone-resistance genes mediated by mobile genetic elements [qnrB2,qnrB4,qnrS1,qnrS4,aac (6')-Ⅰ b-cr] showed positive in some parts of the strains.This was the first report on emergence of qnrS4 in the world.

Coagulase-negative staphylococcus and enterococcus as predominant pathogens in liver transplant recipients with Gram-positive coccal bacteremia / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Gram-positive bacteria such as Staphylococcus aureus have been a common cause of infection among liver transplant (LT) recipients in recent decades. The understanding of local epidemiology and its evolving trends with regard to pathogenic spectra and antibiotic susceptibility is beneficial to prophylactic and empiric treatment for LT recipients. This study aimed to investigate etiology, timing, antibiotic susceptibility and risk factors for multidrug resistant (MDR) Gram-positive coccal bacteremia after LT.</p><p><b>METHODS</b>A cohort analysis of prospectively recorded data was performed to investigate etiologies, timing, antibiotic susceptibility and risk factors for MDR Gram-positive coccal bacteremia in 475 LT recipients.</p><p><b>RESULTS</b>In 475 LT recipients in the first six months after LT, there were a total of 98 episodes of bacteremia caused by Gram-positive cocci in 82 (17%) patients. Seventy-five (77%) bacteremic episodes occurred in the first post-LT month. The most frequent Gram-positive cocci were methicillin-resistant coagulase-negative staphylococcus (CoNS, 46 isolates), methicillin-resistant Staphylococcus aureus (MRSA, 13) and enterococcus (34, E. faecium 30, E. faecalis 4). In all Gram-positive bacteremic isolates, 59 of 98 (60%) were MDR. Gram-positive coccal bacteremia and MDR Gram-positive coccal bacteremia predominantly occurred in patients with acute severe exacerbation of chronic hepatitis B and with fulminant/subfulminant hepatitis. Four independent risk factors for development of bacteremia caused by MDR Gram-positive coccus were: LT candidates with encephalopathy grades II - IV (P = 0.013, OR: 16.253, 95%CI: 1.822 - 144.995), pre-LT use of empirical antibiotics (P = 0.018, OR: 1.029, 95%CI: 1.002 - 1.057), post-LT urinary tract infections (P < 0.001, OR: 20.340, 95%CI: 4.135 - 100.048) and abdominal infection (P = 0.004, OR: 2.820, 95%CI: 1.122 - 10.114). The main infectious manifestations were coinfections due to gram-positive cocci and gram-negative bacilli.</p><p><b>CONCLUSIONS</b>Methicillin-resistant CoNS and enterococci are predominant pathogens among LT recipients with Gram-positive coccal bacteremia. Occurrences of Gram-positive coccal bacteremia may be associated with the severity of illness in the perioperative stage.</p>

Evaluation of aminoglycoside resistance phenotypes and genotyping of acetyltransferase in Escherichia coli / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To investigate the prevalence of aminoglycoside resistance and genotyping of acetyltransferase in Escherichia coli.</p><p><b>METHODS</b>Resistance phenotypes to 12 antibiotics of 44 Escherichia coli isolates were analyzed using agar dilution method and 3 aminoglycoside resistance genes aac(3)-I, II and aac(6')-I were determined by PCR method.</p><p><b>RESULTS</b>In 44 clinical isolates, the occurrence of ESBLs was 45.45%, resistance rates were discrepant for amikacin (18.18%), gentamicin (56.82%) and tobramycin (61.36%), the prevalence of phenotype TG (tobramycin and gentamicin) indicative of aac(3)-II production and TGA (tobramycin, gentamicin and amikacin) indicative of aac(6')-I production were 36.36% and 18.18%, respectively. The most common aminoglycoside resistance genotype of acetyltransferase was aac(3)-II (52.27%) and aac(6')-I was lower (29.55%), but no aac(3)-I was detected.</p><p><b>CONCLUSION</b>At least 2 acetyltransferase genes exist in this area i.e. aac(3)-II and aac(6')-I.</p>

A case-control study on risk factors for nosocomial infection by extended-spectrum beta-lactamases-producing bacteria / 中华预防医学杂志

<p><b>OBJECTIVE</b>To explore the risk factors for nosocomial infection caused by extended-spectrum beta-lactamases (ESBLs)-producing bacteria in hospitals of Zhejiang province.</p><p><b>METHODS</b>One hundred and eighty-five cases with nosocomial infection (108 men and 77 women, with an average age of 55 +/- 17 years) caused by positive-ESBLs bacteria, including 59 cases of respiratory infection, 71 with urinary infection, ten with blood infection, 30 with wound infection and 59 with other infection, and 77 controls with nosocomial infection (54 men and 23 women, with an average age of 54 +/- 20 years) caused by negative-ESBLs bacteria, including 38 cases of respiratory infection, 20 with urinary infection, six with blood infection, eight with wound infection and five with other infection, from six hospitals in Zhejiang Province were studied during May 1999 to May 2000. Data were analyzed with unconditional logistic regression and principal component analysis (PCA).</p><p><b>RESULTS</b>Multivariate unconditional logistic regression analysis showed that the independent risk factors for nosocomial infection were use of the third generation cephalosporins for more than three days (odds ratio, OR 4.52, 95% confidence interval of OR 2.30 - 8.89), combined use of antibiotics (OR 2.86, 95% CI 1.51 - 5.43), use of quinolones for more than three days (OR 2.44, 95% CI 1.18 - 5.04), use of adrenal cortical hormone (OR 2.16, 95% CI 1.08 - 4.31) and oxygen inhalation (OR 2.56, 95% CI 1.14 - 5.72). Five principal components were extracted from the 14 risk factors for nosocomial infection with ESBLs-producing bacteria by principal component analysis, with a contribution of cumulative variance of 60.2%, and arranged in an order as follows, use of ventilator, tracheal intubation or tracheotomy, oxygen inhalation, retaining needle in vein, indwelling urethral catheter, use of the third generation cephalosporins over three days, hospitalization over ten days, use of quinolones over three days, combined use of antibiotics, use of aminoglycosides antibiotic over a week, use of adrenal cortical hormone, catheterized examination and prophylactic use of antibiotics.</p><p><b>CONCLUSIONS</b>Nosocomial infection with ESBLs-producing bacteria could attribute to multiple factors, mainly to invasive manipulation and use of antibiotics.</p>