Evaluation of Tigecycline Susceptibility by Disk Diffusion, E-test and Broth Microdilution Methods in 30 Multidrug Resistant or Extreme Drug Resistant Acinetobacter Isolates

Abstract

Acinetobacter spp. are primarily associated with nosocomial infections and these isolates resistant to most antimicrobial agents. The present study was conducted to evaluate the in vitro susceptibility of tigecyline in multi-drug-resistant (MDR) and extreme-drug resistance (XDR) Acinetobacter strains by three different methods. MDR Acinetobacter isolates described in the study were resistant to at least three of the following antibiotics: imipenem, meropenem, ceftazidime, cefepime, aztreonam, piperacillin tazobactam, ciprofloxacin, tetracycline, ampicillin-sulbactam, trimethoprim-sulfamethoxazole, amikacin, gentamicin and tobramycin. XDR was defined as resistance to all above antibiotics excluding colistin and tigecyline. Identification of Acinetobacter spp. were made conventional methods. Antibiotic susceptibility tests were performed according to the criteria of Clinical and Laboratory Standards Institute (CLSI). All of the isolates were found resistant to carbapenem. Disk diffusion, E-test and broth microdilution methods were used to evaluate the in vitro susceptibility of tigecyline. No tigecycline interpretative criteria universally accepted for Acinetobacter spp, therefore the Food and Drug Administration approved breakpoints for members of the family Enterobacteriaceae have been used. A total of 30 (five strains were MDR and 25 strains were XDR) Acinetobacter strains were isolated from various clinical specimens (8 paracentesis fluid, 8 blood, 7 tracheal aspirates, 5 wound, 2 urine, 2 catheter, 1 sputum) of hospitalized patients in Turgut Ozal Medical Center in 2008 year. All of the MDR and XDR strains were susceptible to tigecyline by broth microdilution method. Against Acinetobacter spp, an MIC range between 0.03 and 0.5 μg/ml was observed by broth microdilution and MIC50 and MIC90 values were determined as 0.12 μg/ml and 0.25 μg/ml, respectively. Twenty five strains (83%) were found susceptible to tigecyline when the disk diffusion brekpoints were considered as ≥16mm susceptible and ≤12mm resistant. Against Acinetobacter spp, an MIC range between 1 and 8 μg/ml was observed by E test. MICs of tigecycline determined by E test were 8 to 64 times higher and 30% (9/30) of the isolates were resistant to tigecycline by E test (MIC breakpoint 2 μg/ml ). Broth microdilution method must to use in the resistant Acinetobacter spp, by E test and disk diffusion method. Key words: Acinetobacter spp; Multi-Drug-Resistance; Tigecycline; E Test; Broth Microdilution.

Keywords

• Acinetobacter spp; Multi-Drug-Resistance; Tigecycline; E Test; Broth Microdilution.

Çoğul Direnç veya Ekstrem İlaç Direnci Olan 30 Acinetobacter Suşunda in Vitro Tigesiklin Duyarlılığının Disk Difüzyon, E-test ve Buyyon Mikrodilüsyon Yöntemleri ile Değerlendirilmesi

Abstract

Acinetobacter türleri sıklıkla nozokomiyal enfeksiyonlara neden olurlar ve çoğu antimikrobiyal ajana dirençlidirler. Bu çalışmada çoğul dirençli (MDR) veya extreme-reziztans (XDR) olarak tanımlanmış Acinetobacter izolatlarında tigesiklin duyarlılığı üç ayrı yöntem ile değerlendirilmiştir. Üçten fazla ilaca (imipenem, meropenem, seftazidime, sefepime, aztreonam, piperasilin-tazobaktam, siprofloksasin, tetrasiklin, ampisilin-sulbaktam, trimetoprim-sülfametoksazol, amikasin, gentamisin ve tobramisin) dirençli olanlar MDR ve tigesiklin ile kolistin dışındaki tüm antibiyotiklere dirençli olanlar XDR olarak alınmıştır. Turgut Özal Tıp Merkezinde 2008 yılında yatan hastalara ait 8 parasentez sıvısı, 8 kan, 7 trakeal aspirat, 5 yara, 2 idrar, 2 katater ve 1 balgamdan izole edilen 30 (beşi MDR ve 25'i XDR) Acinetobacter suşu çalışmaya alınmıştır. Acinetobacter izolatları konvansiyonel yöntemler ile tanımlanmış, antibiyotik duyarlılık testleri Clinical and Laboratory Standards Institute (CLSI) standartlarına göre yapılmıştır. İzolatların tümü karbapenem dirençli olarak değerlendirilmiştir. Tigesiklin duyarlılığı için disk difüzyon, E test (AB BIODISK, Solna, Sweden) ve buyyon mikrodilüsyon yöntemleri kullanılmıştır. Acinetobacter suşlarında tigesiklin için onaylanmış MİK sınır değerleri bulunmadığından, buyyon mikrodilüsyon ve E test sonuçları Enterobacteriaceae ailesi için United States Food and Drug Administration'ın (U.S. FDA) onayladığı tigesiklin MİK sınır değerine (≤ 2 µg/ml duyarlı) göre yorumlanmıştır. MDR ve XDR izolatlarının tümü buyyon mikrodilüsyon testi ile tigesikline duyarlı bulunmuştur. Buyyon mikrodilüsyon çalışılan 30 suşun MİK değerleri 0.03-0.5 μg/ml değerleri arasında olup, MİK50 değeri 0.12 μg/ml, MİK90 değeri 0.25 μg/ml olarak saptanmıştır. Tigesiklin disk difüzyon testinde ≥16mm duyarlı ve ≤12mm dirençli inhibisyon zon çapları kullanılarak 25 suş (% 83) duyarlı bulunmuştur. E test çalışılan 30 suşun MİK değerleri 1-8 μg/ml arasında saptanmıştır. E test ile elde edilen MİK değerleri gerçek MİK değerlerinden 8-64 kat fazla olup, çalışılan Acinetobacter suşlarının %30 (9/30)'u hatalı olarak dirençli bulunmuştur (2 μg/ml MİK kırılma noktasına göre). Sonuç olarak disk difüzyon yöntemi ve E test ile tigesikline dirençli bulunan Acinetobacter suşları için direnci doğrulamada buyyon mikrodilüsyon yöntemi çalışılmalıdır. Anahtar kelimeler: Acinetobacter spp; Çoğul İlaç Direnci; Tigesiklin; E Test; Buyyon Mikrodilüsyon.

Keywords

• Acinetobacter spp; Çoğul İlaç Direnci; Tigesiklin; E Test; Buyyon Mikrodilüsyon.

References

1. Karageorgopoulos DE, Kelesidis T, Kelesidis I, Falagas ME. Tigecycline for the treatment of multidrug-resistant(including carbapenem-resistant) Acinetobacter infections: A review of the scientific evidence. J Antimicrob Chemother 2008; 62: 45-55.
2. Akıncı E, Mumcuoğlu İ, Öngürü P, et al. In vitro activity of Tigecyline against Acinetobacter baumannii strains isolated from nosocomial infections. Turk J Med Sci 2008; 38(6): 583-6.
3. Peleg AY, Seifert H, Paterson DL. Acinetobacter baumannii: Emergence of a successful pathogen. Clin Microbiol Rev 2008; 21(3): 538-82.
4. Perez F, Hujer AM, Hujer KM, et al. Global challenge of multidrug-resistant Acinetobacter baumanni. Antimicrob Agents Chemother 2007; 51(10): 3471-84.
5. Giske CG, Monnet DL, Cars O, Carmeli Y. Clinical and economic impact of common multidrug-resistant gram-negative bacilli. Antimicrob Agents Chemother 2008; 52(3): 813-21.
6. Falagas ME, Bliziotis IA, Kasiakou SK, Samonis G. Outcome of infections due to pandrug-resistance gram-negative bacteria. BMC Infect Disease 2005; 5: 24.
7. Falagas ME, Koletsi PK, Bliziotis IA. The diversity of definitions of multidrug-resistant (MDR) and pandrug-resistant (PDR) Acinetobacter baumannii and Pseudomonas aeruginosa. J Med Microbiol 2006; 55: 1619-29.
8. Livermore DM. Tigecycline what is it, and where should it be used? J Antimicrob Chemother 2005; 56: 611-4.

9. Souli M, Kontopidou FV, Koratzanis E, et al. In vitro activity of tigecycline against multiple-drug-resistant, including pan-resistant, gram-negative and gram-positive clinical isolates from Greek hospitals. Antimicrob Agents Chemother 2006; 50(9): 3166-9.
10. Clinical and Laboratory Standards Institute. Performance Standards for Antimicrobial Susceptibility Testing, M100-S18, 18th informational supplement. CLSI 2008; Wayne, PA.
11. Clinical and Laboratory Standards Institute. Methods for dilution antimicrobial susceptibility tests for bacteria that grow aerobically; approved standard M7-A6. 6th.ed. CLSI, 2006, Wayne, PA.
12. Jones RN, Ferraro MJ, Reler LB, et al. Multicenter studies of tigecycline disk diffusion susceptibility results for Acinetobacter spp. J Clin Microbiol 2007; 45(1): 227-30.
13. Berezin EB, Towner KJ. Acinetobacter spp. as nosocomial pathogens: Microbial, clinical and epidemiological features. Clin Microbial Rev 1996; 9(2): 148–65.
14. Fournier PE, Richet H. The epidemiology and control of Acinetobacter baumannii in health care facilities. Clin Infect Dis 2006; 42: 692-9.
15. Garmendia G, Ortiz-Leyba JLC, Montero GJ, et al. Risk factors for Acinetobacter baumannii nosocomial bacteremia in critically ill patients: a cohort study. Clin Infect Dis 2001; 33: 939-46.
16. Greer ND. Tigecycline (Tygacil): the first in the glycylcycline class of antibiotics. Proc (Bayl Univ Med Cent) 2006; 19: 155-61.
17. Noskin GA. Tigecycline: A new glycylcycline for treatment of serious infections. Clin Infect Dis 2005; 41(Suppl 5): 303-14.
18. Hawkey P, Finch R. Tigecycline: in-vitro performance as a predictor of clinical efficacy. Clin Microbiol Infect 2007; 13: 354- 62
19. Kahlmeter G, Brown DFJ, Canton R, et al. EUCAST technical note on tigecycline. Clin Microbiol Infect 2006; 12: 1147-9.
20. Scheetz MH, Qi C, Warren JR, et al. In vitro activities of various antimicrobials alone and in combination with tigecycline against carbapenem intermediate or resistant Acinetobacter baumannii. Antimicrob Agents Chemother 2007; 51(5): 1621-6.
21. Mezzatesta ML, Trovato G, Gona F, et al. In vitro activity of tigecyline and comparators against carbapenem-susceptible and resistant Acinetobacter baumannii clinical isolates in Italy. Ann Clin Microbiol Antimicrob 2008; 7: 4.
22. Hoban DJ, Bouchillon SK, Dowzicky MJ. Antimicrobial susceptibility of extended-spectrum β-lactamase producers and multidrug-resistant Acinetobacter baumannii throughout the United States and comparative in vitro activity of tigecycline, a new glycylccycline antimicrobial. Diagn Microbiol Infect Dis 2007; 57: 423-8.
23. Song JY, Kee SY, Hwang IS, et al. In vitro activities of carbapenem/sulbactam combination, colistin, colistin/rifampicin combination and tigecycline against carbapenem-resistant Acinetobacter baumannii. J Antimicrob Chemother 2007; 60: 317-22.
24. Mansur A, Kuzucu Ç, Ersoy, Yetkin F. İnönü Üniversitesi Turgut Özal Tıp Merkezinde 2008 yılında yatan hastalardan izole edilen Acinetobacter suşlarının antibiyotik duyarlılıkları. ANKEM 2009; 23(4): 177-81.
25. Zer Y, Akın Özgür FE, Namıduru M. Acinetobacter baumannii suşlarında tigesiklin etkinliğinin araştırılması. İnfeksiyon Dergisi 2007; 21(4): 193-6.
26. Bogaerts P, Naas T, Wybo I, et al. Outbreak of infection by carbapenem-resistant Acinetobacter baumannii producing the carbapenemase OXA-58 in Belgium. J Clin Microbiol 2006; 44(11): 4189-92.
27. Ratnam I, Franklin C, Spelman W. In vitro activities of new and conventional antibiotics against multi-drug resistant gram negative bacteria from patients in the intensive care unit. Pathology 2007; 39(6): 586-8.
28. Pillar M, Draghi DC, Dowzicky MJ, Sahm DF. In vitro activity of tigecycline against gram-positive and gram-negative pathogens as evaluated by broth microdilution and E test, J Clin Microbiol 2008; 46(9): 2862-7.
29. Thamlikitkul V, Tiengrim S, Tribuddharat C. Comment on: High tigecycline resistance in multidrug-resistant Acinetobacter baumannii. J Antimicrob Chemother 2007; 60: 177-8.
30. Akın Özgür FE, Bayram A, Balcı İ. Çoğul dirençli Acinetobacter baumannii izolatlarında kolitsin, polimiksin B ve tigesiklin direncinin saptanmasında disk difüzyon, E test ve buyyon mikrodilüsyon yöntemlerinin karşılaştırılması. Mikrobiyol Bul 2010; 44: 203-10.
31. Petersen PJ, Bradford PA. Effect of medium age and supplementation with the biocatalytic oxygen-reducing reagent oxyrase on in vitro activities of tigecycline against recent clinical isolates. Antimicrob Agents Chemother 2005; 49(9): 3910-8.
32. Hope R, Warner M, Mushtaq S, Ward ME, Parsons T, Livermore DM. Effect of medium type, age and aeration on the MICs of tigecycline and classical tetracyclines. J Antimicrob Chemother 2005; 56: 1042-6.
33. Mazarrasa CF, Mazarrasa O, Calvo J, Arco A, Martínez LM. High concentrations of manganese in Mueller–Hinton agar increase MICs of tigecycline determined by E-test.. J Clin Microbiol 2009; 47(3): 827-9.
34. Thamlikitkul V, Tiengrim S. Effect of different Mueller–Hinton agars on tigecycline disc diffusion susceptibility for Acinetobacter spp. J Antimicrob Chemother 2008; 62: 847-8.