Gul Durmaz

Optimum Detection Times for Bacteria and Yeast Species with the BACTEC 9120 Aerobic Blood Culture System: Evaluation for a 5-Year Period in a Turkish University Hospital

ABSTRACT We tracked and documented the time of positivity of blood cultures by using the BACTEC 9120 (Becton Dickinson Diagnostic Instrument Systems) blood culture system over a 5-year study period. A 7-day protocol of the incubation period was selected, and a total of 11,156 blood cultures were evaluated. The clinically significant microorganisms (32.95%) were isolated in 3,676 specimens. Gram-positive and -negative bacterial isolation rates were found to be 41.07 and 44.88%, respectively. Yeasts were found in 14.03% of all pathogens. Both the false-positivity and -negativity rates were very low (0.1 and 0.3%, respectively). The mean detection times for all of the pathogens were determined to be 19.45 h. Yeasts, nonfermentative gram-negative bacteria, and Brucella melitensis strains were isolated within 5 days. By taking these data into account, we decided to establish a 5-day-incubation protocol in our laboratory instead of the 7 days that are commonly used.

Tigecycline treatment of multi-drug-resistant Corynebacterium jeikeium infection in a child with relapsing and refractory acute lymphoblastic leukemia.

Corynebacterium jeikeium has been recognized as an important cause of infection, particularly among neutropenic patients who have central venous catheter (CVC). Routine use of tigecycline in children is not yet approved. Here in we present a child with relapsed‐refractory lymphoblastic leukemia who was successfully treated with tigecyline due to multi‐drug‐resistant C. jeikeium sepsis without removal of CVC. Our case highlights the use of tigecycline where there are no alternatives. Further studies regarding the efficacy and safety of tigecycline in pediatric patients are needed. Pediatr Blood Cancer. 2010;55:349–351.

In vitro activity of ertapenem and other carbapenems against extended-spectrum beta-lactamase producing Escherichia coli and Klebsiella pneumoniae clinical isolates in a tertiary care center in Turkey.

Objective: To evaluate the in vitro effect of ertapenem, imipenem and meropenem in clinical isolates of extended-spectrum β-lactamase (ESBL)-producing strains of Escherichia coli and Klebsiella pneumoniae. Design/methods: We studied 82 consecutive clinical isolates of ESBL-producing E. coli (n = 49) and K. pneumonia (n = 33) between February 2006 and September 2007. The minimum inhibitory concentration for each carbapenem was determined using the agar dilution method. Results: Eighty two consecutive microorganisms from sterile sites were evaluated. A total of 48.8% of patients had a history of surgical intervention, 78.0% needed urinary catheterization, 57.3% required vascular access and 40.3% mechanical ventilation; and 70.7% had a history of ICU stay. High resistance rates were shown for both E. coli and K. pneumoniae against cefepime (81.7%), ciprofloxacin (50.9%), tetracycline (75.0%), co-trimoxazole (47.4%), and gentamicin (48.7%). In addition, most K. pneumoniae and E. coli isolates were susceptible to amikacin (78.3%) and piperacilline-tazobactam (91.5%). Meropenem and imipenem showed activity against 100% of the isolates. Ertapenem showed activity against 100% of K. pneumoniae isolates, against 95.9% of E. coli isolates and against 97.5% of the 82 ESBL-producing microorganisms. Two E. coli isolates showed ertapenem resistance. Conclusion: In recent literature, carbapenems were the most active antimicrobial agents against ESBL-producing Enterobacteriaceae, as in our study. This is the first study on the in vitro activity of ertapenem against ESBL-producing E. coli and K. pneumoniae conducted in Turkey. In view of the serious infections caused by ESBL-producing microorganisms, therapeutic interventions are still problematic in serious clinical conditions. Ertapenem may be a good choice for treatment, with the additional advantage of being a once a day regimen.

Methicillin-resistant S. aureus colonization in intensive care unit patients: Early identification and molecular typing

INTRODUCTION Early detection of methicillin-resistant Staphylococcus aureus (MRSA) in colonized patients is very important for infection control procedures to prevent MRSA spread. We aimed to monitor MRSA carriage in intensive care unit (ICU) patients and to evaluate the speed and efficiency of conventional culture, immunological, chromogenic, and molecular methods together with genotyping. METHODOLOGY Nasal and axillar swab specimens were obtained from patients in the ICUs of the general surgery and neurosurgery wards in a tertiary hospital once a week over four weeks between December 2009 and July 2010. Oxacillin and cefoxitin disk diffusion tests, oxacillin agar screening test, latex agglutination test, chromogenic agar, and real-time polymerase chain reaction (PCR) tests were used for isolation and identification of MRSA. MRSA isolates were typed using ribotyping and pulsed-field gel electrophoresis (PFGE) typing. RESULTS MRSA colonization was detected in 48 of 306 patients by real-time PCR. The MRSA colonization rate was 6.2%, 15.5%, and 38.5% at admission and in the first and second weeks, respectively. Sensitivity, specificity, positive and negative predictive values for all phenotypic tests were 98%, 99.6%, 98%, and 99.6%, respectively. The shortest handle time was observed in PCR. A total of three banding patterns were obtained from MRSA isolates by ribotyping, and PFGE analyses revealed 17 different pulsotypes varying from 11 to 18 distinct bands, showing high genetic diversity among the samples. CONCLUSION Phenotypic MRSA screening tests in our study exhibited similar performances. The superiority of real-time PCR is its short turnaround time.

Evaluation of an automated system for the detection of carbapenem resistant Acinetobacter baumannii and assessment of metallo-β-lactamase production using two different phenotyping methods

We tested 200 clinical Acinetobacter baumannii isolates against imipenem and meropenem using the methods of broth microdilution, disk diffusion, agar dilution, MicroScan/WalkAway automated system. Very major errors were mostly obtained between MicroScan/WA system and disk diffusion test. MicroScan/WA system generated unacceptable errors. Combined disk and modified Hodge tests used for detection of metallo-β-lactamase production were practical and useful.

Comparison of Methods Used For The Diagnosis of Epstein-Barr Virus Infections in Children

The accurate diagnosis of Epstein-Barr virus (EBV) infections is important, as many other infectious agents or diseases can cause similar symptoms. In this study, sera of pediatric patients who were suspected to have an EBV infection, were sent to Eskisehir Osmangazi University Faculty of Medicine, Department of Clinical Microbiology, and investigated by IFA, ELISA, immunoblotting and Real-time PCR. The performances of these tests were compared with IFA. The rates of agreement between ELISA and IFA were found as 100% for seronegative, 100% for acute primary infection, 22.2% for late primary infection, 92.1% for past infection. The rates of agreement between immunoblotting and IFA were found as 80.8% for seronegative, 68.8% for acute primary infection, 55.6% for late primary infection, 86.6% for past infection. The sensitivity of immunoblotting for anti-VCA IgM was identical with ELISA, and higher for anti-VCA IgG, anti-EBNA IgG, anti-EA antibodies, while the specificity of immunoblotting for these antibodies were found to be lower. The sensitivity and specificity of Real-time PCR for detection of viremia in acute primary infection were found as 56.25% (9/16) and 97.89% (139/142), respectively. The diagnostic methods should be chosen by evaluating the demographic characteristics of patients and laboratory conditions together.