Acinetobacter baumannii isolates in a tertiary care hospital: Antimicrobial resistance and clinical significance

Journal of Microbiology and Infectious Jaggi Diseases N et al./ Acinetobacter baumannii isolates 2012; 2 (2): 57-63 57 JMID doi: 10.5799/ahinjs.02.2012.02.0043 ORIGINAL ARTICLE Acinetobacter baumannii isolates in a tertiary care hospital: Antimicrobial resistance and clinical significance Namita Jaggi1, Pushpa Sissodia2, Lalit Sharma3 Microbiology, Director, Labs & Infection Control, Gurgaon, Haryana-122001, India Microbiology, Executive Microbiologist, Laboratory Services, Gurgaon, Haryana-122001, India 3 Microbiology, Senior Microbiology Technician, Laboratory Services, Gurgaon, Haryana-122001, India 1 2 ABSTRACT Objectives: To carry out a retrospective study on Acinetobacter baumannii isolates from various clinical samples in a tertiary care hospital in India and analyze its epidemiology, antibiotic susceptibility patterns, pathogenic potential and nosocomial status. Materials and methods: The clinical specimens over a period of 14 months from December 2008 to January 2010 were analyzed and the A.baumannii isolates obtained by an automated identification system (Vitek 2 Compact) were segregated for further study. Their antibiograms were studied and a clinical correlation was made to assess their pathogenic status and mode of acquisition. Further, the nosocomial infections acquired during this period were studied and the contribution made by A.baumannii was calculated to assess its nosocomial status. Results: A.baumannii was isolated in 155 samples out of 1632 gram negative isolates (9.4% prevalence) from the entire hospital. Maximum isolates were from respiratory secretions (57.4%) followed by blood (23.8%). Prevalence of A.baumannii rose to 22.7% (119 out of 525) in intensive care unit (ICU) and 65 isolates (54.6%) proved to be pathogenic. A.baumannii contributed to 30.4% ventilator associated pneumonia, 35.2% Catheter Associated Blood Stream Infections, 12.5% Surgical Site Infections and 2.94% Catheter Associated Urinary Tract Infections. Overall resistance of A.baumannii towards carbapenems was 90% from all hospital isolates. ICU isolates showed higher resistance (93.2%) as compared to Inpatient Department (82.7%) and Out-patient Department (57.1%). Conclusion: In this study, A.baumannii isolates showed a pathogenic potential of around 54.6% and a majority were found to be carbapenem resistant. We must be cognizant of the fact that all A.baumannii isolations doesn’t necessarily mean infection and antibiotics should only be given in clinically proven infections. J Microbiol Infect Dis 2012; 2(2): 57-63 Key words: A.baumannii; prevalence; resistance patterns; clinical correlation; nosocomial status Üçüncü basamak bir hastanede Acinetobacter baumannii izolatları: Antimikrobiyal direnç ve klinik önemi ÖZET Amaç: Retrospektif bir çalışma ile değişik klinik örneklerden izole edilen Acinetobacter baumannii suşlarının değerlendirmesi yapılarak epidemiyolojileri, antibiyotik duyarlılık paternleri, patojen potansiyelleri ve hastane kaynaklı oluşları analiz edildi. Gereç ve yöntem: Aralık 2008’den Ocak 2010’a kadar 14 ay süreyle klinik örnekler incelendi ve otomatik tanı sisteminin (Vitek 2 Compact) tanımladığı A.baumannii suşları alınarak ileri çalışmalar için ayrıştırıldı. Bu suşların antibiyogramları çalışıldı, patojenlik durumlarına alındıkları kaynaklarla klini uyumları karşılaştırılarak karar verildi. Ayrıca bu dönemde nozokomiyal enfeksiyonları hesaplanarak A.baumannii’nin bunlara katkısı değerlendirildi. Bulgular: Toplam olarak izole edilen 1632 gram negatif suşun 155’i (% 9,4) A.baumannii idi. En fazla suş solunum salgılarından (% 57,4) ve kandan (% 54,6) elde edildi. A.baumannii prevalansı yoğun bakım ünitesinde (YBÜ) % 22,7’ye çıkarken (525’de 119) bunların 65’i (% 54,6) patojen olarak teyit edildi. A.baumannii ventilator ilişkili pnömonilerin % 30,4’üne, kateter ilişkili kan dolaşımı enfeksiyonlarının % 35,2’sine, cerrahi alan enfeksiyonlarının % 12,5’ine ve kateter ilişkili üriner sistem enfeksiyonlarının % 2,94’ünde etken olarak bulundu. Tüm hastane izolatlarında toplam olarak A.baumannii suşlarının karbapenemlere direnci % 90 idi. YBÜ suşları karbapenemlere karşı Yatan Hasta Departmanı suşlarına ve Ayaktan Takip Departmanı suşlarına göre daha yüksek bir direnç göstermekteydiler (sırasıyla, % 93,2, % 82,7 ve % 57,1). Sonuç: Bu çalışmada A.baumannii suşları % 54,6 civarında bir patojen potansiyeli gösterdiler ve ekseriyeti karbapenemlere dirençli idi. Tüm A.baumannii izolasyonlarının enfeksiyon anlamına gelmediği ve antibiyotiklerin sadece klinik olarak teyit edlien enfeksiyonlarda kullanılması gerektiği gerçeğinin farkında olmalıyız. Anahtar kelimeler: A.baumannii, prevalans, direnç paternleri, klinik uyum, nozokomiyal Correspondence: Namita Jaggi, M.D. Artemis Health Institute, Sector 51, Gurgaon, Haryana-122001, India Email: Received: 11 January, 2012, Accepted: 20 April, 2012 and Infectious Diseases 2012, All rights reserved J Microbiol Infect DisCopyright © Journal of Microbiology www.jmidonline.org Vol 2, No 2, June 2012 58 Jaggi N et al. Acinetobacter baumannii isolates INTRODUCTION Members of the genus Acinetobacter have emerged from organisms of questionable pathogenicity to pan resistant nosocomial pathogens worldwide in the past two or three decades, especially since 2005-2006.1 There are more than 30 genomic types of Acinetobacter identified so far, of which more than two third of Acinetobacter infections are due to Acinetobacter baumannii. A.baumannii colonizes healthy humans transiently at a low density on the warm and moist skin of axilla, groin, between toes, throat, nares and intestinal tract but it generally does not cause infection.2 In the hospital environment, A.baumannii can colonize the respiratory, urinary, gastrointestinal tract and wounds of the patients and can cause infections in burn, trauma, mechanically ventilated and immunocompromised patients. It shows a special predilection for the ICU.3 The epidemiological, clinical, prognostic, and therapeutic characteristics of A.baumannii isolated from infected patients have been studied widely in the last decade.4 The most alarming problems encountered during this period are the organism’s ability to accumulate diverse mechanisms of resistance and the emergence of strains that are resistant to all commercially available antibiotics coupled with the lack of new antimicrobial agents in the pipeline.5 This has resulted in a limited choice of antibiotics for treatment of multidrug resistant isolates of A.baumannii. The most active agents in vitro against the multidrug resistant A.baumannii are the polymixins- polymixin B and polymixin E (Colistin) and tigecycline.6 In our study undertaken over a period of 14 months (Dec 2008-Jan 2010) at a tertiary care super speciality hospital, we report the prevalence of A.baumannii isolates, their antibiograms and their clinical significance. Their contribution as causative agents of nosocomial infections has also been evaluated. MATERIALS AND (...truncated)