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Yayın Beyin tümörlü hastadan izole edilen corynebacterium pseudodiphtheriticum: olgu sunumu(Maltepe Üniversitesi, 2010) Balıkçı, Ahmet; Uraz, Mahmure; Şimşek, Selçuk; Belas, Zeliha; Topkaya, Aynur ErenCorynebacterium pseudodiphtheriticum insan deri ve üst solunum yollarının flora üyesidir. Nadiren pnömoni etkeni olarak bildirilmektedir. Beyin tümörü nedeniyle tedavi edilen hastanın trakeal aspiratında C. pseudodiphtheriticum üretilmiştir. Sonuç olarak, bu olgu ile, hem immunsuprese hem de immunkompetan hastalarda, flora üyesi bakterilerin de etken olabileceğine ve Klinik Mikrobiyoloji laboratuvarı nda kültürler değerlendirirken flora üyesi bakterilerin doğru yorumlanması gerektiğine dikkat çekilmek istendi.Yayın Blood Culture Positivity: Is It Pathogen or Contaminant?(ANKARA MICROBIOLOGY SOC, 2013) Balikci, Ahmet; Belas, Zeliha; Eren Topkaya, AynurBlood culture is the gold standard for diagnosis of bloodstream infections. Many studies have shown that rapid isolation and identification of the microorganisms in blood culture and initiation of early antimicrobial therapy are critically important to reduce the mortality rate. It was found that the rate of contamination in blood cultures is increasing with automated systems developed to facilitate the growth of microorganism and tracking positivity. It is more difficult to interpret a positive blood culture result especially in the case of having only one sample bottle. In this study the effect of growth time observed in the automated blood culture systems was evaluated in terms of interpretation of blood culture results as being pathogens or contaminants. A total of 1201 blood cultures tested in BACTEC 9120 (Becton Dickinson, USA) system in Maltepe University Hospital Medical Microbiology Laboratory, Istanbul, Turkey during one-year period were included in the study and growth times were recorded for positive bottles. The decision about the growth as being a pathogen or contamination was made by considering the clinical condition of the patient, the number of positive blood cultures and the results of inflammation markers (white blood cell counts, procalsitonin and CRP levels). Of the blood cultures 290 (24%) yielded positive results and 73% (212/290) of them were evaluated as pathogens, while 27% (78/290) were identified as contaminants. The mean detection time for clinically significant isolates was 17.87 hours and for contaminants was 40.56 hours. The difference between the growth time of pathogens and contaminants was found statistically significant (p< 0.0001). With regard to all positive results, it was detected that 66% of the bacteria grew within the first 24 hours. While 29.6% of the pathogens grew within 12 hours, none of the contaminants grew during that time. The evaluation of growth time among staphylococci in terms of methicillin resistance revealed that methicillin- resistant staphylococci grew later (26 hours) than the susceptible ones (11 hours) both in the pathogen group and the contaminant group (p< 0.01). The data of our study emphasized that, the growth time detected in blood culture systems had a critical role in estimating whether the isolated microorganism is a pathogen or a contaminant, especially in case of lack of more than one blood samples. It was concluded that, the bacterial growth detected within the first 24 hours most probably indicated the microorganism as pathogen, while blood culture positivity detected after 48 hours strongly pointed out that it was contaminant. However, it should be considered that methicillin-resistant staphylococci needed much longer time than 24 hour for growth, both as pathogens or contaminants.Yayın A Frequently Overlooked Bacteria in Clinical Microbiology Laboratories: Arcanobacterium haemolyticum(ANKARA MICROBIOLOGY SOC, 2011) Balikci, Ahmet; Topkaya, Aynur E.; Belas, ZelihaArcanobacterium haemolyticum, previously known as Corynebacterium haemolyticum, is a facultative anaerobic, gram-positive bacillus with negative catalase and positive CAMP inhibition test results. It may be the causative agent of about 0.5-3% of acute bacterial pharyngitis especially in children and young adults. Since growth of A.haemolyticum is usually inhibited by flora members and since it slowly develops hemolysis in sheep blood agar and its colony morphology resembles beta-hemolytic streptococci, it is frequently overlooked in the evaluation of throat cultures. The aims of this study were to investigate the isolation frequency of A.haemolyticum from the throat cultures of pediatric patients by using both sheep and human blood agar media, and to evaluate the performances of those media for the identification of A.haemolyticum. A total of 355 patients (median age: 7 years) who were admitted to pediatric outpatient clinics with the symptoms of tonsillopharyngitis between March-July 2010 period, were included in the study. Swab samples obtained from tonsils and posterior oropharynx were inoculated into a divided plate which contained 5% sheep blood agar in one half and 5% human blood agar in the other half. After incubation in 5% CO(2) at 37 degrees C, the beta-hemolytic colonies with a microscopic morphology of gram-positive bacilli were further evaluated on 24, 48 and 72(th) hours. Identification of A.haemolyticum was based on negative catalase test, positive reverse CAMP test and biochemical characteristics obtained by API-Coryne (bioMerieux, France) identification system. In our study, beta-hemolytic colonies were detected in the throat cultures of 56 (16%) patients, of which 14% (49/355) were identified as beta-hemolytic streptococci (46 group A, 2 group G, 1 group C), and 2% (7/355) were identified as A.haemolyticum. All of the A.haemolyticum isolates were characterized by the production of beta-hemolysis in human blood agar at 24 hours, while the beta-hemolysis generation time in sheep blood agar was 48 hours for four isolates and 72 hours for three isolates. A.haemolyticum was identified in 2% of children with tonsillopharyngitis during the five months study period in spring/summer. All of the strains were isolated at human blood agar in 24 hours. Thus, in order to isolate A.haemolyticum in routine throat cultures, sheep blood agar plates together with human blood agar plates should be used in clinical microbiology laboratories.
