Aylin Üsküdar Güçlü

Comparison of Culture and PCR Methods in Detection of Haemophilus influenzae, Streptococcus pneumoniae and Moraxella catarrhalis in Children with Otitis Media with Effusion

Objective: The etiology and pathogenesis of otitis media with effusion (OME) is still unclear despite many studies within the last four decades. Polymerase chain reaction (PCR) based procedures are suggested for detection of the causative bacteria supposed to inflict multiple infections. In the current study, culture and PCR based approaches were used to detect the frequency of Haemophilus influenzae, Streptococcus pneumoniae and Moraxella catarrhalis, which have been known as common pathogens in middle ear effusions (MEE) of patients with otitis media. Material and Methods: The DNAs of these three bacteria were detected by standard and multiplex PCR techniques in MEE specimens and their diagnostic values were evaluated in comparison to the conventional culture method. Results: Samples from 67 OME suspected children were analysed retrospectively. Two H. influenzae and two M. catarrhalis isolates were recovered by conventional culture method (6.0%; 4/67). Out of the 67 samples, seven S. pneumoniae, nine H. influenzae, and eleven M. catarrhalis isolates were detected vith PCR. In five samples, two concurrent bacteria were detected in following combinations: two S. pneumoniae and H. influenzae, two S. pneumoniae and M. catarrhalis, and one H. influenzae and M. catarrhalis. Sensitivity, specificity, positive predictive value and negative predictive value rates of the PCR technique were 100.0%, 71.4%, 18.2% and 100.0%, respectively. The difference between culture and PCR was statistically significant (p<0.001). Conclusion: Although the specificity and positive predictive values are low, PCR, which allows rapid screening is feasible for detecting the most common fastidious bacteria that lead to OME.

Evaluation of microorganisms isolated from blood cultures and their susceptibility to antibiotics in two year period.

Bloodstream infections (BSIs) are a major cause of healthcare-associated morbidity and mortality. Analyses of the frequency of microorganisms isolated from blood cultures and antibiotic susceptibility can provide clinicians with relevant information for the empirical treatment of patients. The purpose of the study was to investigate to frequency of microorganisms isolated from blood cultures and their sensitivity to antimicrobial agents between January 2009 and December 2010 at the Training Hospital of Gulhane Military Medical Faculty. Blood cultures were processed by automatized BACTEC/9050 (Becton Dickinson, Maryland, USA). The observed growth of microorganisms in culture media was identified by conventional methods and PhoenixTM 100 automatized systems (BD Phoenix System, Beckton Dickinson, USA).Antimicrobial susceptibility tests were performed by Kirby-Bauer disc diffusion method and automatized systems (BD Phoenix System, Beckton Dickinson, USA) in accordance with the recommendations of Clinical and Laboratory Standarts Institute (CLSI). In the study period among the 6823 blood culture samples, 957 (14%) yielded positive results. Results of 600 (8.7%) blood culture samples evaluated as contamination. Of the 957 isolated microorganisms, 61.0% were Gram negative, 31.1% were Gram positive and 7.8% were yeast. E.coli was the most frequently isolated species (15.9%), followed by Klebsiella spp (15.4%) and Coagulase Negative Staphylococcus (CNS) (13.2%). Twenty eight percent% of S. aureus and 89% of CNS isolates were resistant to methicillin. Only one isolate (1.73%) was resistant to glycopeptides among Enterococcus spp. ESBL (Extended-spectrum beta lactamase) was detected in 36.8% of E.coli and 51.3% of Klebsiella spp. isolates.