[Evaluation of penicillin-binding protein genotypes in penicillin susceptible and resistant Streptococcus pneumoniae isolates]. / Penisiline Duyarli ve Dirençli Streptococcus pneumoniae Izolatlarinda Penisilin Baglayan Protein Genotiplerinin Degerlendirilmesi.

Penicillin-binding proteins (PBPs) are the natural targets of beta-lactam antibiotics and mutations in pbp1a, pbp2b, and pbp2x genes, which encode PBPs, are responsible for resistance to beta-lactams in Streptococcus pneumoniae. In the present study, we intended to determine how often the common mutation patterns occurred within the pbp1a, pbp2b, and pbp2x PBP gene regions and evaluate the PBP genotype mutations which were associated with penicillin resistance in several penicillin-susceptible and - resistant S.pneumoniae isolates in Mersin, Turkey. A total of 62 S.pneumoniae strains isolated from different clinical specimens (32 nasopharyngeal swab, 16 sputum, 3 blood, 3 wound, 2 cerebrospinal fluids and one of each urine, abscess, bronchoalveolar lavage, conjunctival swab, tracheal aspirate, middle ear effusion) were included in the study. Penicillin susceptibilities of the isolates were searched by disc diffusion and E-test methods, and 23 of them were identified as susceptible, 31 were intermediate susceptible, and eight were resistant to penicillin. A rapid DNA extraction procedure was performed for the isolation of nucleic acids from the strains. Distribution of PBP gene mutations in pbp1a, pbp2b, and pbp2x gene regions related to penicillin resistance was determined by using a wild-type specific polymerase chain reaction (PCR) based technique. PBP gene alterations of those isolates were also evaluated in relation to penicillin susceptibility and resistance patterns. Twenty two (95.7%) of 23 penicillin-susceptible S.pneumoniae isolates exhibited no mutation in the three PBP genes (pbp1a, pbp2x, and pbp 2b), while 1 (4.3%) of these harbored mutations in all of the three PBP genes. The penicillin-intermediate susceptible S.pneumoniae isolates exhibited various combinations of mutations. One (3.2%) of 31 penicillin-intermediate susceptible isolates exhibited no mutation in the three PBP genes, while 22 (71%) of them yielded mutations in all of the three PBP genes. The remaining 8 (25.8%) isolates harbored mutations for dual PBP genes (in five strains pbp1a and pbp2b; in two strains pbp2x and pbp2b; in one strain pbp1a and pbp2x). Seven (87.5%) out of eight penicillin-resistant S.pneumoniae isolates (MIC ≥ 2 µg/ml) revealed mutations in all of the three PBP genes and the other penicillin-resistant isolates exhibited no mutation in the PBP genes. The present study supplied important data on the frequency of different patterns of mutations occurring at various regions of PBP genes related to penicillin resistance in S.pneumoniae isolates in our restricted region. The results supported the notion that penicillin resistance in S.pneumoniae was mainly attributed to alterations in pbp1a, pbp2x, and pbp2b gene regions and wild-type sequence specific PCR could be applied to characterize genotypic background of penicillin resistance in S.pneumoniae strains.

[Isolation and identification of Mycobacterium bovis and non-tuberculous mycobacteria in raw milk samples in Mersin province]. / Mersin Ilinde Çig Sütlerden Mycobacterium bovis ve Tüberküloz Disi Mikobakterilerin Izolasyonu ve Tanimlanmasi

This study was aimed to isolate and identify Mycobacterium bovis and non-tuberculous mycobacteria (NTM) species in raw milk samples from cattles and to compare the diagnostic performance of the methods used for that purpose. A total of 145 raw milk samples from cattles were collected from five villages in Mersin province (located on Mediterrenean region of Turkey) between April and June 2008. Presence of mycobacteria was investigated by Ehrlich Ziehl Neelsen (EZN) staining method, culture in Löwenstein- Jensen (LJ) medium and polymerase chain reaction (PCR). Only 1 (0.7%, 1/145) raw milk sample was found to be acid fast bacilli (AFB) positive with EZN staining. Eleven (7.6%) samples were positive by culture and mycobacterial DNA was detected in 6 (4.1%) samples by PCR. Mycobacterium was isolated from both creamy and pellet layer of a culture positive sample. Identification was carried out with conventional biochemical tests, PCR-Restriction Fragment Length Polymorphisms (PCR-RFLP) and spoligotyping (spacer oligonucleotide typing) methods. One isolate was identified as Mycobacterium tuberculosis complex (MTC) and 11 isolates were identified as NTM out of 12 isolates those were isolated from culture. According to PCR-RFLP analysis of these 11 NTM isolates, 6 (54.5%) were Mycobacterium genavense, 2 (18.2%) were Mycobacterium simiae, 2 (18.2%) were Mycobacterium szulgai and 1 (9.1%) was Mycobacterium fortuitum. MTC isolate was identified as M.bovis by spoligotyping. According to the results of our study, both pellet and creamy layers from raw milk samples should be cultured to selective LJ medium (without glycerol, with 0.4% sodium pyruvate) to improve the chance of isolation and must be incubated for up to eight weeks. In our region, NTM were isolated in 6.9% and M.bovis in 0.7% of the raw milk samples from cattles and this emphasized the risk of transmission of mycobacteria to man via direct contact or ingestion of unpasteurized milk products.