Antibiotic susceptibility patterns among respiratory isolates of Gram-negative bacilli in a Turkish university hospital

BACKGROUND: Gram-negative bacteria cause most nosocomial respiratory infections. At the University of Cumhuriyet, we examined 328 respiratory isolates of Enterobacteriaceae and Acinetobacter baumanii organisms in Sivas, Turkey over 3 years. We used disk diffusion or standardized microdilution to test the isolates against 18 antibiotics. RESULTS: We cultured organisms from sputum (54%), tracheal aspirate (25%), and bronchial lavage fluid (21%). The most common organisms were Klebsiella spp (35%), A. baumanii (27%), and Escherichia coli (15%). Imipenem was the most active agent, inhibiting 90% of Enterobacteriaceae and A. baumanii organisms. We considered approximately 12% of Klebsiella pneumoniae and 21% of E. coli isolates to be possible producers of extended-spectrum beta-lactamase. K. pneumoniae isolates of the extended-spectrum beta-lactamase phenotype were more resistant to imipenem, ciprofloxacin, and tetracycline in our study than they are in other regions of the world. CONCLUSIONS: Our results suggest that imipenem resistance in our region is growing

Retrospective analysis of antibiotic susceptibility patterns of respiratory isolates of Pseudomonas aeruginosa in a Turkish University Hospital

BACKGROUND: Lower respiratory tract infections due to Pseudomonas aeruginosa have a high mortality rate. Antibacterial activity of various antibiotics against P. aeruginosa isolated from each hospital depends on the variety or amount of antibiotics used in each hospital. METHOD: A total of 249 respiratory isolates of Pseudomonas aeruginosa in Sivas (Turkey) were included between January-1999 and January-2002. Isolates were tested against 14 different antibiotics by a disc diffusion method or standardized microdilution technique. RESULTS: Organisms were cultured from the following specimens: sputum (31.3%), transtracheal/endotracheal aspirates (37.8%), and bronchial lavage (30.9%). Isolates in bronchial lavage were highly susceptible to cefoperazone and aminoglycosides. Resistance to ampicillin/sulbactam was 98.8%, ticarcillin 40.1%, ticarcillin/clavulanic acid 11.2%, piperacillin 21.8%, aztreonam 66.6%, cefotaxim 75.4%, ceftriaxone 84.2%, cefoperazone 39.0%, ceftazidime 50.8%, gentamicin 57.5%, tobramycin 58.4%, amikacin 25.4%, ciprofloxacin 16.1%, and imipenem/cilastatin 21.6%. The term multidrug-resistant P. aeruginosa covered resistance to imipenem, ciprofloxacin, ceftazidime, gentamicin, and piperacillin. 1.2% of isolates were multidrug-resistant. CONCLUSIONS: These findings suggest that amikacin resistance increases progressively in Turkey. Piperacillin and ticarcillin/clavulanate were the most active agents against both imipenem- and ciprofloxacin-resistant isolates in our region

Antimicrobial Resistance Patterns of Enterococcus faecalis and Enterococcus faecium Bacteria Isolated from Bloodstream Infections

Introduction: Enterococci have recently become one of the most common causes of nosocomial bloodstream infections. Today, these bacteria account for about 10% of all bacteria. This study aimed to determine the rates of resistance to antibiotics that are commonly used in the treatment of Enterococcus faecalis and Enterococcus faecium strains isolated from nosocomial bloodstream infections. Materials and Methods: The study included the E. faecalis and E. faecium strains isolated from bloodstream infections at the Practice and Research Hospital of the Faculty of Medicine, Cumhuriyet University over a total period of four and a half years between (January 2009 and June 2013). Strain typing and antimicrobial sensitivity testing were performed using an automated system (BD, Phoenix, AZ, USA) according to the guidelines of the Clinical and Laboratory Standards Institute. Nosocomial bloodstream infection diagnosis was based on the diagnostic criteria of the Centers for Diseases Control and Prevention. Results: One hundred and three enterococci strains were isolated from nosocomial bloodstream infections during the study period. 51 (49.5%) of these strains were typed as E. faecalis and 52 (50.5%) as E. faecium. While there were 44 (84.6%) ampicillin-resistant strains among E. faecium isolates, this number was 2 (3.9%) (p= 0.001) among E. faecalis strains. High-level aminoglycoside resistance rate (500 µg/mL) was higher among E. faecium isolates compared with E. faecalis isolates (63.5% vs. 33.3%; p= 0.002). While no linezoid or daptomycin resistance was noted among the strains, only 2 (1.9%) of a total of 103 enterococci strains were found to be resistant to both vancomycin and teicoplanin. Conclusion: Problems caused by the resistance of nosocomial pathogens to antimicrobials are rapidly increasing. Therefore, clinical centers should constantly update and share their available data in relation to drug resistance. We consider that the local findings of this study, conducted at a university hospital, can be used particularly in fighting against nosocomial enterococcal infections to contribute to the formation of successful empirical treatment models

The Prevalence of Extended-Spectrum Beta-Lactamase and Antibiotic Resistance among Escherichia coli and Klebsiella pneumoniae Isolates Responsible for Nosocomial Blood-Stream Infections

Introduction: This study aimed to identify the extended-spectrum beta-lactamase (ESBL) production prevalence of Escherichia coli and Klebsiella pneumoniae strains isolated from nosocomial bloodstream infections as well as their resistance to the antibiotics used. Materials and Methods: This study examined the E. coli and K. pneumoniae strains isolated from blood-stream infections at the Health Care and Research Hospital, Faculty of Medicine, Cumhuriyet University, between 2009 and 2012. Strain description and antimicrobial susceptibility tests were carried out using an automated system (BD, Phoenix, AZ, USA) based on the recommendations of the Clinical and Laboratory Standards Institute (CLSI). Results: This study examined 321 E. coli and 104 K. pneumoniae strains isolated from nosocomial blood-stream infections. ESBL was found in 38.3% of E. coli strains and in 26.9% of K. pneumoniae strains isolated from blood cultures. No resistance was found in any strains to carbapenems. Amikacin was considered to be the second-least resistant antibiotic for these strains. One hundred and thirtyfour of the 425 nosocomial strains were isolated from intensive care units and 291 from other services. Fifty-six percent of strains isolated from intensive care units were found to be E. coli and 44% as K. pneumoniae. ESBL was found in 57.3% of E. coli and 30.5% of K. pneumoniae strains isolated from intensive care units, and this ratio was found to be 32.5% and 22.2%, respectively, for other units. Conclusion: Increasing rates of resistance are being reported worldwide in studies carried out with E. coli and K. pneumoniae strains raising future concerns. Thus, resistance data should be constantly updated. We conclude that the local data gathered in this study can be used in the fight against relevant bacterial nosocomial bloodstream infections and can be effective in creating successful empirical treatment models and preventing the spread of such microorganisms

Vancomycin Resistant Enterococcus Outbreak in a University Hospital: Investigation of Risk Factors

Introduction: In this study, independent risk factors for the acquisition of vancomycin resistant enterococcus (VRE) were investigated prospectively between September 2011 and March 2012 in a nosocomial VRE outbreak at a university hospital. Materials and Methods: After the detection of a VRE strain from wound culture sample of an inpatient in September 2011, a VRE outbreak was assumed in the hospital, and VRE surveillance was performed both at high-risk and VRE detected clinics. For the detection of gastrointestinal system (GIS) VRE colonization, weekly rectal swab specimens were taken from the hospitalized patients and when considering an infection, blood, urine and wound specimens were sent to the microbiology laboratory for each patient. The patients whom rectal swab and/or clinical specimens yielded VRE were accepted as VRE positive. Determining vancomycin resistance genotype among the VRE strains were done with multiplex polymerase chain reaction technique (GenExpert®, USA) by using the special test kits (Xpert®, USA). Results: During the seven-month of VRE outbreak, a total of 74 VRE positive patients, 6 (8.1%) of whom infected by a VRE in seven different clinics were determined. These 74 VRE positive patients and 1136 patients who were accepted as VRE negative (all were hospitalized in the same clinical wards) by the surveillance cultures were divided into two groups for comparing patient characteristics. A multivariate logistic regression analysis showed sulbactam-ampicillin [Odds ratio (OR) 3.18, 95% confi dence interval (95% CI) 1.70-5.97; p< 0.001], vancomycin (OR 5.16, 95% CI 1.92-13.9; p= 0.001), piperacillin/tazobactam (OR 4.09, 95% CI 1.85-9.45; p= 0.001), carbapenems (imipenem, meropenem) (OR 2.43, 95% CI 2.03-10.1; p< 0.001) and amikacin (OR 7.4, 95% CI 2.71-20.19; p< 0.001) use, all were detected as independent risk factors for VRE positivity. Further, diabetes mellitus (OR 2.44, 95% CI 1.31-4.53; p= 0.005), abdominal surgical operation (OR 2.49, 95% CI 1.18-5.29; p= 0.017), and the application of a nasogastric feeding tube (OR 0.31, 95% CI 0.13- 0.75; p= 0.01) were also determined as independent risk factors for VRE-acquisition. Seventy-three out (98.6%) of 74 VRE strains were both vancomycin [minimum inhibitor concantration (MIC) > 16 μg/mL)] and teicoplanin (MIC > 16 μg/mL) resistant (vanA genotype) Enterococcus faecium. Conclusion: The use of parenteral form of broad spectrum antibiotics and underlying diseases like diabetes and nasogastric tube applications, all increase nosocomial VRE risk

Mortality predictors of Staphylococcus aureus bacteremia: a prospective multicenter study

Background: Staphylococcus aureus is one of the causes of both community and healthcare-associated bacteremia. The attributable mortality of S. aureus bacteremia (SAB) is still higher and predictors for mortality and clinical outcomes of this condition are need to be clarified. In this prospective observational study, we aimed to examine the predictive factors for mortality in patients with SAB in eight Turkish tertiary care hospitals

Results of a Multicenter Study Investigating Plasmid Mediated Colistin Resistance Genes (mcr-1 and mcr-2) in Clinical Enterobacteriaceae Isolates from Turkey

Colistin is a polymyxin antibiotic which is considered as one of the last line agents against infections due to multidrug resistant or carbapenem resistant gram-negative pathogens. Colistin resistance is associated with chromosomal alterations which can usually cause mutations in genes coding specific two component regulator systems. The first plasmid-mediated colistin resistance gene, mcr-1 was described in Escherichia coli and Klebsiella pneumoniae isolates in December 2015 and followed by another plasmid-mediated colistin resistance gene mcr-2 in 2016. The rapid and interspecies dissemination of plasmid-mediated resistance mechanisms through horizontal gene transfer, have made these genes considerably threatening. After the first reports, although mcr-1/mcr-2 producing Enterobacteriaceae isolates have been reported from many countries, there have been no reports from Turkey. Thus, the aim of this study was to investigate the presence of mcr-1/mcr-2 in clinical Enterobacteriaceae isolates from different parts of our country. A total of 329 Enterobacteriaceae isolates from 22 laboratories were collected which were isolated between March, 2015 and February, 2016. mcr-1/mcr-2 were investigated by polymerase chain reaction during February-March, 2016. Two hundred and seventeen of Klebsiella pneumoniae (66%), 75 of Salmonella spp. (22.8%), 31 of Esherichia coli (9.4%), 3 of Enterobacter cloacae (0.9%), 2 of Klebsiella oxytoca (0.6%) and 1 of Enterobacter aerogenes (0.3%) isolates were included to the study. Agarose gel electrophoresis results of PCR studies have shown expected band sizes for positive control isolates as 309 bp for mcr-1 and 567 bp for mcr-2. However, the presence of mcr-1/mcr-2 genes was not detected among the tested study isolates of Enterobacteriaceae. Although mcr-1/mcr-2 were not detected in our study isolates, it is highly important to understand the mechanism of resistance dissemination and determine the resistant isolates by considering that colistin is a last-line antibiotic against infections of multidrug or carbapenem resistant gram-negative bacteria. Thus, it is suggested that these mechanisms should be followed-up in both clinical and non-clinical (e.g. isolates from food animals, raw meats and environment) isolates of special populations