Hicran GÜLER, Çınar ÖZTÜRK, Burcu CİLO DALYAN, Melda SINIRTAŞ, Cüneyt ÖZAKIN

CLSI’ nin 2008 öncesi ve 2008 kriterlerine göre dokuz yılda izole edilen 643 Streptococcus pneumoniae suşunda penisilin duyarlılığının değerlendirilmesi

İnvaziv pnömokok izolatlarının penisilin sınır değerleri Clinical and Laboratory Standards Institute (CLSI) tarafından 2008 yılında yeniden tanımlanmıştır. Bu çalışmada, dokuz yıllık (2000-2008) periyotta, klinik örneklerden izole edilen 612 (% 95.2) menenjit dışı infeksiyon ve 31 (% 4.8) menenjit etkeni olan toplam 643 Streptococcus pneumoniae suşunun E test yöntemiyle penisiline MİK değerleri belirlenmiş ve sonuçlar önceki ve yeni sınır değerlere göre yorumlanmıştır. Ayrıca CLSI standartlarına uygun olarak disk difüzyon yöntemi ile bazı diğer antibiyotiklere duyarlılık araştırılmıştır. Menenjit dışı örneklerden izole edilen 612 suştan 2008 öncesi sınır değerleri ile 432 (% 70.6) suş penisiline duyarlı bulunurken, 155 (% 25.3) suş orta düzeyde dirençli, 25 (% 4.1) suş yüksek düzeyde dirençli saptanmıştır. Yeniden belirlenen (2008) değerlerle penisiline duyarlı suşlar ile orta düzeyde penisiline dirençli suşların sayısı sırasıyla 601 (% 98.2) ve 11 (% 1.8) olmuş, yüksek düzeyde penisiline dirençli suş saptanmamıştır. Menenjitli hasta izolatlarında 25 (% 80.6) suş iki değerlendirmede de penisiline duyarlı bulunmuştur. Bu izolatlarda önceki sınır değerlerle yüksek düzeyde penisilin direnci olan suş saptanmazken, 2008 sınır değerlerine göre 6 (% 19.4) suş yüksek düzeyde penisilin dirençli olarak değerlendirilmiştir. Tüm suşlar içinde, eritromisine 73 (% 11.4), klindamisine 48 (% 7.5), kotrimoksazole 141 (% 21.9), tetrasikline 76 (% 11.8) ve kloramfenikole 20 (% 3.1) suş dirençli (dirençli veya orta düzeyde duyarlı) bulunmuştur. Rifampisin direncine bir suşta rastlanmıştır. Pnömokok suşlarının 78’inde (% 12.1) çoklu ilaç direnci saptanmıştır. Sonuç olarak yeniden düzenlenen penisilin duyarlılık sınır değerleri menenjit dışı invaziv pnömokok infeksiyonlarında direnç oranlarını aşağı çekmiştir ve tedavide penisilin yine önemli bir seçenek olarak görülmektedir. Bununla beraber önceki yıllarda ODPD izolatları yüksek veya artma eğilimindeki bölgelerde klinisyenlerin daha dikkatli olmaları gereklidir. Menenjit etkeni suşlar için durum ters yöndedir. Pnömokok sürveyans çalışmalarının yapılması ihtiyacı devam etmektedir.

Evaluation of penicillin susceptibility of 643 Streptococcus pneumoniae strains isolated in nine years according to the former and 2008 CLSI breakpoints

Penicillin resistance breakpoints of invasive pneumococcal isolates are redefined by the Clinical and Laboratory Standards Institute (CLSI) in 2008. In this article, the penicillin susceptibilities of 643 Streptococcus pneumoniae strains (612 from nonmeningitis and 31 from meningitis cases) isolated in nine-year period (2000-2008) were determined by E-test method and evaluated according to the former and new breakpoints of CLSI. Also, the susceptibilities of the strains to some other antibiotics were determined by disk diffusion according to CLSI standards. When the former breakpoints of CLSI are considered, 432 (70.6 %) of 612 strains from nonmeningitis cases were found susceptible, 155 (25.3 %) strains intermediate-level resistant and 25 (4.1 %) strains high-level resistant to penicillin. According to new breakpoints 601 (98.2 %) of these strains were found susceptible, 11 (1.8 %) intermediate-level resistant to penicillin. There were no strain with high-level resistance. In strains from meningitis cases, 25 (80.6 %) strains were found penicillin susceptible by both breakpoints. Six (19.4 %) intermediate-level resistant strains with the former breakpoints evaluated as high level resistant according to the 2008 breakpoints. Among all 643 strains, the resistance (resistance and intermediately resistance) to erythromycin was found in 73 (11.4 %), to clindamycin in 48 (7.5 %), to cotrimoxazole in 141 (21.9 %), to tetracycline in 76 (11.8 %) and to chloramphenicol in 20 (3.1 %) strains. Rifampicin resistance was found only in one strain. Multidrug resistance was observed in 78 (12.1 %) strains. In conclusion, the new penicillin susceptiblity breakpoints have decreased the resistance rates in nonmeningitis invasive pneumococcal infections and penicillin continues to be a significant option in treatment. Nonetheless, clinicians in regions where the rate of resistant isolates have been high in previous years or are inclined to raise should be careful. In meningitis cases, the situation is opposite. The need for pneumococcal surveillance studies continues.

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