Transition from CLSI to EUCAST: How our antibiotic susceptibility tests will be affected

Objective: Two standard guidelines are commonly used worldwide. In our country CLSI guidelines have been used up to recent years, but currently, a transition to EUCAST standards has begun in many centers. In this study the effect of transition from CLSI guideline to EUCAST guideline on antibiotic susceptibility test (AST) reports in a high prevalence region for antibiotic resistance was investigated. Methods: Non-duplicated 5003 isolates (1902 Enterobacteriaceae, 1261 Acinetobacter baumannii, 697 Pseudomonas aeruginosa, 424 Staphylococcus aureus, 336 Enterococcus faecalis, 257 Enterococcus faecium, and 126 Stenotrophomonas maltophilia) isolated from the samples sent from intensive care units (ICUs) were included in the study. The identifications of the microorganisms were performed with Bruker Microflex MS (Bruker Daltonics, Bremen, Germany) system, and their AST were evaluated with Phoenix automated system (BD, Sparks, MD, USA). The MIC values were interpreted according to the breakpoints indicated in CLSI and EUCAST guidelines. Results: The highest resistance increase among Enterobacteriacea was seen to beta lactam/ betalactamase inhibitor combinations, followed by cephalosporins, quinolones and aminoglycosides. ESBL positive Enterobacteriaceae isolates were found more resistant to cephalosporins. The resistance rates of A. baumannii and P. aeruginosa seemed increased for quinolones, aminoglycosides and cephalosporins, however colistin resistance remained unchanged. All Gram-negative bacilli included in the study had decreased resistance rates for imipenem and meropenem. Similarly, S. maltophilia isolates had a decreased resistance rate for trimethoprim-sulfamethoxazole. While methicillin resistance rate did not change for S. aureus, minor changes were encountered for other antibiotic groups. There is no categorical changes observed at the susceptibility of enterococci to ampicillin, vancomycin, teicoplanin and linezolid. Conclusion: Transition to EUCAST guideline in our hospital did not affect AST results of Gram- positive bacteria isolated from the patients in ICU. However, higher resistance rates were observed for all antibiotic groups except carbapenems in Gram- negative bacteria. As a result, following the current epidemiological data according to the standard used is of great importance in terms of determining the appropriate treatment.

CLSI’den EUCAST’a geçiş: Antibiyotik duyarlılık testlerimiz nasıl etkilenecek

Amaç: Antibiyotik duyarlılık testlerinde iki standart kılavuz tüm dünyada yaygın olarak kullanılmaktadır. Ülkemizde son yıllara kadar CLSI kılavuzu kullanılmakta iken, günümüzde birçok merkezde EUCAST kılavuzuna geçildi. Bu çalışmada, antibiyotik direnci açısından yüksek prevalanslı bir merkezde CLSI kılavuzundan EUCAST kılavuzuna geçişin antibiyotik duyarlılık test (AST) raporlarına etkisi araştırıldı. Yöntem: Yoğun bakım ünitesinden gönderilen örneklerden izole edilen tekrar içermeyen 5.003 izolat (1.902 Enterobacteriaceae, 1.261 Acinetobacter baumannii, 697 Pseudomonas aeruginosa, 424 Staphylococcus aureus, 336 Enterococcus faecalis, 257 Enterococcus faecium ve 126 Stenotrophomonas maltophilia) çalışmaya dahil edildi. Suşların tanımlanmasında Bruker Microflex MS (Bruker Daltonics, Bremen, Germany) sistemi kullanıldı. Antibiyotik duyarlılık sonuçları için Phoenix otomatize sistemi (BD, Sparks, MD, USA) ile elde edilen MİK değerleri, CLSI ve EUCAST kılavuzlarında belirtilen direnç sınır değerlerine göre yorumlandı. Bulgular: Enterobacteriacea’da en yüksek direnç artışının beta laktam / beta-laktamaz inhibitör kombinasyonlarında, ardından sefalosporinler, kinolonlar ve aminoglikozitlerde olduğu görüldü. ESBL pozitif Enterobacteriaceae izolatlarının sefalosporinlere karşı daha dirençli olduğu bulundu. A. baumannii ve P. aeruginosa’nın direnç oranları kinolonlar, aminoglikozidler ve sefalosporinler için artmış görünse de kolistin için direnç değişmedi. Çalışmaya dahil edilen tüm gram-negatif basillerde, imipenem ve meropenem için direnç oranları azaldı. Benzer şekilde, S. maltophilia izolatları trimetoprimsülfametoksazol için düşük direnç oranına sahipti. Metisilin direnç oranı S. aureus için değişmezken, diğer antibiyotik gruplarında minör değişikliklerle karşılaşıldı. Enterokokların ampisilin, vankomisin, teikoplanin ve linezolide duyarlılığında kategorik bir değişiklik gözlenmedi. Sonuç: Hastanemizde YBÜ hastalarından izole edilen gram pozitif bakterilerin ADT sonuçlarını EUCAST kılavuzuna geçiş etkilemedi. Ancak, gram-negatif bakterilerdeki karbapenemler hariç tüm antibiyotik grupları için daha yüksek direnç oranları gözlendi. Sonuç olarak, kullanılan standarda göre güncel epidemiyolojik verilerin takip edilmesi, uygun tedavinin belirlenmesi açısından büyük önem arz etmektedir.

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