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Objectives : To determine the serotype distribution of pneumococcus causing invasive pneumococcal disease (meningitidis, bacteremia and empyema) in children in Turkey, and to observe potential changes in this distribution in time to guide effective vaccine strategies. Methods : We surveyed S. pneumoniae with conventional bacteriological techniques and with real-time polymerase chain reaction (RT-PCR) in samples of cerebrospinal fluid (CSF), blood and pleural fluid. S. pneumoniae strains were isolated from 33 different hospitals in Turkey, which are giving health services to approximately 60% of the Turkish population. Results : A total of 167 cases were diagnosed with invasive pneumococcal disease between 2015 and 2018. We diagnosed 52 (31.1%) patients with meningitis, 104 (62.2%) patients with bacteremia, and 11 (6.6%) patients with empyema. Thirty-three percent of them were less than 2 years old and 56% less than 5 years old. Overall PCV13 serotypes accounted for 56.2% (94/167). The most common serotypes were 19 F (11.9%), 1 (10.7%) and 3 (10.1%). Conclusions : Besides the increasing frequency of non-vaccine serotypes, vaccine serotypes continue to be a problem for Turkey despite routine and high-rate vaccination with PCV13 and significant reduction reported for the incidence of IPD in young children. Since new candidate pneumococcal conjugate vaccines with more serotype antigens are being developed, continuing IPD surveillance is a significant source of information for decision-making processes on pneumococcal vaccination.

Colistin resistant Acinetobacter baumannii strains are of great concern worldwide. However, the role of efflux pumps in colistin resistance needs to be elucidated. We investigated the changes in colistin MICs of 29 colistin resistant A. baumannii isolates in response to resistance-nodulation-division (RND)-type efflux pump inhibitor (EPI) and the alterations in AdeR and AdeS two-component regulatory proteins previously associated with the overproduction of AdeAB. The EPI, 1-(1-naphthylmethyl)-piperazine (NMP), led to significant reductions in colistin MICs. At least one of the following amino acid substitutions was found in AdeS proteins from 18 of the isolates: L172P, A94V, V27I, V32I, G186V, and G164A. Besides, A136V and V120I alterations were identified in AdeR from five isolates. Therefore, EPI-responsive colistin resistance in our isolates is most likely due to the action of an RND-type efflux system. The underlying mechanism of resistance might be the result of certain AdeRS alterations, leading to AdeAB overexpression.

Resistance of Streptococcus pneumoniae (750) to penicillin, erythromycin, chloramphenicol and trimethoprim/sulfamethoxazole isolated in 4 Turkish hospitals between 1996 and 1999 was evaluated according to year of isolation, patients' age groups and specimen. Penicillin susceptibility was determined by E-test strips and the other antibiotics were tested by disk diffusion test following the NCCLS guidelines in each center. Overall high and intermediate resistance to penicillin was 3% and 29%, respectively. There was a significant difference (p<0.001) between the centers with regard to penicillin resistance. However, there was no significant increase in resistance by year. Penicillin resistance varied significantly among children and adults (36% versus 25%) and according to the specimen. Highest rate of penicillin resistance was observed in respiratory specimens (36%) followed by ear exudates (33.5%). In blood isolates, resistance to penicillin was 28.6%. Overall resistance to erythromycin was 8%, to chloramphenicol 5% and to trimethoprim-sulfamethoxazole 47%. Although overall penicillin resistance in these Turkish S. pneumoniae isolates is high, resistance rates vary in each center and have not increased from 1996 to 1999.