DUYGU PERÇİN RENDERS, Bülent SÜMERKAN, Demet AYANGİL, MURAT TELLİ

Brucella melitensis suşlarının antibiyotik duyarlılıklarının belirlenmesinde agar dilüsyon ve E-test yöntemlerinin karşılaştırılması

Klinik örneklerden izole edilen 74 B.melitensis suşunun altı farklı antibiyotiğe duyarlılıkları NCCLS agar dilüsyon referans yöntemi ve E-test yöntemi ile araştırılarak sonuçlar karşılaştırılmıştır. Bütün izolatlar seftriakson (MİK $leq$, 1 $mu$g/ml), siprofloksasin (MİK $leq$, 0.5 )$mu$g/ml), doksisikün (MİK $leq$ 0.125 $mu$glml), streptomisin (MİK $leq$ 2 $mu$glml) ve trimetoprim-sulfametoksazole (TMP-SMZ) (MİK $leq$ 0.519.5 $mu$glml) duyarlı iken suşlarının 14'ünün (% 19) NCCLS'in Haemophilus türleri için belirlediği sınır değerler dikkate alındığında rifampisine azalmış duyarlılık gösterdiği belirlenmiştir. İki yöntem arasında iki kat dilüsyon içerisindeki uyum (essential agreement) seftriakson için % 99, siprofloksasin için % 95, doksisiklin için % 98, rifampisin için % 97, streptomisin için % 88 olarak bulunmuştur. En düşük uyum TMP-SMZ'de görülmüştür (% 27). Bu bulgular ışığında E-test yönteminin B.melitensis suşları için alternatif bir duyarlılık test yöntemi olarak kullanımının sınırlı olacağı sonucuna varılmıştır.

Anahtar Kelimeler:

Koloni sayımı, mikrobiyal, Brucella melitensis, Mikrobiyolojik teknikler

Comparison of agar dilution method and E-test in the determination of antibiotic susceptibility of Brucella melitensis strains

The patterns of antimicrobial susceptibility of 74 clinical isolates of Brucella melitensis to six antimicrobial agents were determined by the National Committee for Clinical Laboratory Standards (NCCLS) agar dilution reference method and E-test. The results obtained by the agar dilution method were compared to those generated by the E-test agar gradient diffusion method. All B. melitensis isolates were found to be susceptible to ceftriaxone (MICs $leq$ 1 $mu$g/ml), ciprofloxacin (MICs $leqle$ 0.5 $mu$glml), doxycycline (MICs $leq$ 0.125 $mu$g/ml), streptomycin (MICs $leq$ 2 $mu$glml), and trimetoprim-sulfamethoxazole (TMP-SMX) (MICs $leq$ 0.5/9.5 $mu$g/ml). Of the isolates, 14 (19 %) were intermediately resistant to rifampicin according to the NCCLS breakpoints for Haemophilus spp. The essential agreements between two methods within two-doubling dilution were 99 %for ceftriaxone, 95 %for ciprofloxacin, 98'% for doxycycline, 97 %for rifampicin, and 88 %for streptomycin. The lowest aggrement was seen with TMP-SMX (27 %). In conclusion, discrepancies between the two test methods limits the use of E-test as an alternate susceptibility testing method for B.melitensis.

Keywords:

Colony Count, Microbial, Brucella melitensis, Microbiological Techniques,

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