Hande ARSLAN, Funda ERGİN, Kuru Emine İNCİ, Göknur YAPAR, Özlem Kurt AZAP

In vitro activity of colistin against nonfermentative gram-negative bacilli

Giriş: Çoklu ilaç direnci olan gram-negatif bakterilerdeki direnç problemi, yoğun bakım ünitelerinde hemen her gün karşılaşılan önemli bir sorundur. Kolistin, gram-negatif bakterilerin tedavisinde kullanılmış ancak nefrotoksisite nedeniyle kullanımdan kaldırılmıştır. Gram-negatif basillerde kolistin duyarlılığı saptanarak, kolistin duyarlılığı için bir sınır değer belirlenmesi amaçlandı.Gereç ve yöntem: Yüz otuz iki çoklu ilaç direnci olan gram negatif bakteri test edildi. Minimum inhibitör konsantrasyon değerleri agar dilüsyon yöntemi ile belirlendi.Bulgular: Duyarlılık sınırı ≤ 4 mg/L olarak kabul edildiğinde 55 P. aeruginosa suşunun 52’si (%94.1), 48 A. baumanii suşunun 46’sı (%95.8), 21 S. maltophilia suşunun 15’i (%71.4) ve 8 B. cepacia suşunun 1’i (%8.4) kolisitine duyarlı bulundu. Duyarlılık sınırı ≤ 2 mg/L olarak alındığında ise 55 P. aeruginosa suşunun 33’ü (%60), 48 A. baumanii suşunun 41’i (%85.4) kolistine duyarlı bulunurken, S. maltophilia ve B. cepacia suşlarında duyarlılık saptanmadı.Sonuç: Duyarlılık sınırı ≤ 4 mg/L olarak kabul edildiğinde kolistin in vitro koşullarda P. aeruginosa ve A. baumanii suşlarına etkilidir. Kolistinin gram-negatif bakteriler için duyarlılık sınır değerinin belirlenebilmesi, daha çok sayıda klinik çalışma ile sağlanabilecektir.

Kolistinin non-fermentatif gram-negatif bakterilere in-vitro etkinliğinin değerlendirilmesi

Aim: Multidrug-resistant gram-negative isolates have become a problem in everyday clinical practice in intensive care units. Colistin was once used for treatment of gram-negative bacteria, but its systemic use has been completely abandoned due to nephrotoxicity. It was aimed to assess the in-vitro susceptibility of several gram-negative isolates to determine a standardized breakpoint for colistin. Methods: One hundred thirty-two multidrug-resistant nonfermentative gram-negative isolates were tested. Minimum inhibitory concentrations were determined using an agar dilution technique. Results: Fifty-two of 55 P. aeruginosa isolates (94.1%), 46 of 48 A. baumannii isolates (95.8%), 15 of 21 S. maltophilia isolates (71.4%), and 1 of 8 B. cepacia isolates (8.4%) were susceptible to colistin at a breakpoint of ≤ 4 mg/L. The number of susceptible strains dropped at a susceptibility breakpoint of ≤ 2 mg/L: 33 of 55 P. aeruginosa isolates (60%), and 41 of 48 A. baumannii isolates (85.4%) were susceptible; none of the S. maltophilia or B. cepacia isolates was susceptible at this breakpoint. Conclusion: Colistin maintains effectiveinvitroactivityagainst P. aeruginosa and A. baumannii when used at a breakpoint of ≤ 4 mg/L. Further clinical trials are needed to determine which susceptibility criterion is more suitable for clinical practice (≤ 4 mg/L or ≤ 2 mg/L), and to determine a standard breakpoint for all gram-negative bacteria.

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