Association of doripenem resistance with OXA-type carbapenemases in Acinetobacter baumannii isolates.

OBJECTIVES: To evaluate the in vitro activity of doripenem in Acinetobacter baumannii (A. baumannii) clinical isolates that possess different OXA-type carbapenemases, and to evaluate the roles of these enzymes in the development of carbapenem resistance. METHODS: This retrospective study was conducted with 25 A. baumannii isolates at Sakarya University Training and Research Hospital, Sakarya, Turkey from June to October 2014. Antibiotic susceptibility testing was carried out using the Vitek-2 automated system (bioMérieux, Marcy l'Etoile, France). Minimum inhibitory concentrations (MICs) were determined using Etest strips (bioMérieux, Marcy l'Etoile, France). Quantitative polymerase chain reaction was performed in a Fluorion Instrument (Iontek, Istanbul, Turkey).  RESULTS: Isolates were divided into 5 groups based on their susceptibility profiles and OXA-type carbapenemase positivity. Group 2 isolates whose MIC of both meropenem and doripenem are in the range of 4-32 µg/mL were negative for both blaOXA-23 and blaOXA-58. Group 3 isolates whose MIC of meropenem and doripenem is in the range of 4-32 µg/mL, blaOXA-23 is positive, and blaOXA-58 is negative. Group 5 isolates whose MIC of meropenem is more than 32 µg/mL, and that of doripenem is in the range of 16-32 µg/mL were positive for both blaOXA-23 and blaOXA-58.  CONCLUSION: The blaOXA-23 and blaOXA-58 gene combinations may confer resistance with a much greater MIC of both meropenem and doripenem. But the blaOXA-58 presence alone was not correlated with doripenem resistance.

[Changes in antibiotic resistance of Pseudomonas aeruginosa isolates over the past 11 years in Turkey: a meta-analysis]. / Meta-analiz: Türkiye'de Pseudomonas aeruginosa izolatlarinin son 11 yildaki antibiyotik direnç degisimi.

The increased antibiotic resistance and diversity of resistance mechanisms in clinical isolates of Pseudomonas aeruginosa lead to serious problems in treatment. Bacterial resistance against antibiotics can be influenced by patient characteristics, antibiotic usage policy depending on the country, region, hospital, clinics and even may vary during treatment. In this meta-analysis study, we aimed to evaluate the trends in P.aeruginosa antibiotic resistance over the past 11 years. The study was planned and conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and the literature search method, criteria for inclusion and exclusion, evaluation of publications, data collection, and statistical analysis were performed. To identify relevant publications, two national databases (ULAKBIM and TURK MEDLINE) and one international database (PubMed) were searched. Published manuscripts were evaluated for exclusion criteria, after the study data were collected, and statistical analyses were performed. The data obtained from the literature were assessed under a common unit. The calculations made in the 95% confidence interval value of p≤0.05 was considered statistically significant. As a result of exclusion criteria, meta-analysis was performed for 48 studies published between 2003 and 2013. For the evaluation of the changes in antibiotic resistance of P.aeruginosa isolates over time, studies were divided into three groups according to the year of publication. The number of publications was relatively consistent over the course of the study period with 17 studies published in 2003-2006; 14 in 2007-2009, and 17 in 2010-2013. There were significant changes in antibiotic resistance results within years however, none of these differences were statistically significant (p>0.05). Carbapenem resistance, especially imipenem resistance, increased between 2007 and 2009, however, the changes were not statistically significant for either imipenem or meropenem (p=0.254, p=0.499, respectively). Through the 11-year period, the resistance rates for imipenem and meropenem were 29.4% and 32.1%, respectively. In the last 4 years of the study period, notable decrease were reported in antibiotic groups except for cefepime from cephalosporins and monobactam; the resistance rates for cephalosporins remained unchanged during this time period. The reported resistance rates for cefepime and ceftazidime were 41.4% and 43.9%, respectively. Similar decreases in resistance to aminoglycoside antibiotics, including amikacin, gentamicin, netilmicin, and tobramycin, were also seen, however, these changes were not statistically significant (p>0.05). The current data suggested that antibiotic resistance in P.aeruginosa has a tendency to decrease in our country. Though being at the bottom of the ladder, it can be expressed that rational and restricted use of antibiotics policy, contributed to the strength of the decrease; however for the decline of resistance to a reasonable level, new and sustainable policy is necessary to be implemented.

[Antibiotic resistance patterns of Escherichia coli strains isolated from urine cultures in Turkey: a meta-analysis]. / Türkiye'de Idrar Kültürlerinden Izole Edilen Escherichia coli Suslarinin Antibiyotiklere Direnç Durumu: Bir Meta-Analiz.

Escherichia coli is the most frequently isolated microorganism from both community-acquired and nosocomial urinary tract infections in Turkey. A large number of studies concerning antibiotic susceptibility of E.coli have been published from different centers throughout the country. The aim of this study was to evaluate the antibiotic resistance patterns of E.coli strains isolated from urine cultures by a meta-analysis in published medical literature between the years of 1996-2012 in Turkey. The study was planned and conducted in accordance with the declaration of PRISMA and describes the methods of literature search, the determining criteria for inclusion and evaluation of articles, data collection and statistical analysis. To find the published series Google Scholar and PubMed international databases were used to access published manuscripts evaluated according to the determined criteria for acceptance and rejection. For each study, general data and antibiotic resistance rates were collected as a common unit. Publications considered as lacking in appropriate content was eliminated from the study. Statistical analysis of the data obtained were 95% confidence intervals, and p≤ 0.05 value was considered as significant difference. A total of 228 articles were found to be published during 1996-2012 period, while 101 of them were included in the meta-analysis according to the eligibility criteria. The analyses indicated that nitrofurantoin and piperacillin resistance rates have been decreased, whereas ciprofloxacin, cefepime, co-trimoxazole and extended-spectrum beta-lactamase (ESBL) positivity rates have been increased during the study period. The increases in the rates of ciprofloxacin and cefepime resistance and and ESBL production were statistically-significant (p< 0.05). A significant reduction in resistance rates for ampicilin, amoxicillin-clavulanate, and amikacin was noted in pediatric patients between 2002-2012. Ceftriaxone, imipenem, gentamicin and amikacin resistance were not homogenous between the geographical regions, and statistically significant differences were observed for amoxicillin-clavulanate, cefuroxime and ciprofloxacin resistance rates (p< 0.05). Antibiotic resistance rates, except for imipenem, in bacterial strains, isolated from hospitalized patients were found significantly higher in strains obtained from outpatients. The differences between those groups were significant in terms of ampicilin, amoxicillin-clavulanate, cefuroxime, ceftriaxone, trimethoprim-sulfamethoxazole, gentamicin, ciprofloxacin, amikacin and cefepime resistances (p< 0.05). It has been noted that antibiotic resistance patterns of E.coli strains isolated from urine cultures between 1996-2012 demonstrated significant variability, and many studies were based only on laboratory data. The results of this meta-analysis demonstrated that the resistance rates in commonly-used antibiotics for empirical therapy were high. In conclusion, information obtained by systematic evaluation of national data will be valuable for the determination of optimal antibiotic regimens and in prevention of unnecessary antibiotic use.

[Investigation of the Presence of Disinfectant Resistance Genes qacA/B in Nosocomial Methicillin-Resistant Staphylococcus aureus Isolates and Evaluation of Their In Vitro Disinfectant Susceptibilities]. / Hastane Enfeksiyonu Etkeni Olan Metisiline Dirençli Staphylococcus aureus Suslarinda qacA/B Dezenfektan Direnç Genlerinin Varligi ve Dezenfektanlara In Vitro Duyarliliklarinin Arastirilmasi

Development of resistance to disinfectant substances in nosocomial microorganisms is an important problem encountered during disinfectant practices. Methicillin-resistant Staphylococcus aureus (MRSA) remains a significant cause of hospital-acquired infections. Besides being resistant to several antimicrobial agents, MRSA strains can also become resistant to some disinfectant substances. Resistance to disinfectant substances may develop due to the misuse of disinfectants. This may either be due to the frequent use of disinfectant substances or use in lower concentrations than recommended. MRSA strains may harbour the qacA/B disinfectant resistance genes that may cause resistance to quarternary ammonium compounds and some cationic disinfectants. These resistance genes are found in plasmids and are responsible for decreased susceptibility or resistance. In this study, a total of 69 nosocomial MRSA strains isolated from clinical specimens in our hospital were tested for disinfectant activity and the presence of qacA/B disinfectant resistance genes in these isolates was investigated by polymerase chain reaction. We determined whether the presence of these genes caused phenotypic resistance to chlorhexidine and benzalkonium chloride by the use of bactericidal and bacteriostatic tests. For this purpose, the minimum inhibitory concentration (MIC) values of these disinfectants against MRSA isolates were detected by microdilution method with the proposals of CLSI, and bactericidal effects of these disinfectants were also detected by using quantitative suspension test according to EN13727:2003 European Standard. It has been found that 11.6% (8/69) of the isolates harbored qacA/B resistance genes. MIC values for chlorhexidine and benzalkonium chloride were found in the range of 2-8 µg/ml. Although it was observed that MIC values were higher in five of the qacA/B gene positive isolates, statistically significant difference was not found between gene positive and gene negative groups. Both 1% chlorhexidine and 1% benzalkonium chloride were found bactericidal against the isolates including the ones carrying the qacA/B resistance genes. It was concluded that the presence of the qacA/B disinfectant resistance genes did not lead to resistance to the disinfectant substances at the concentrations used in clinical practices. Furthermore, tested disinfectants still exhibited bactericidal activity even with high MIC values.