Introduction: Microbial biofilms are important virulence factors contributing not only to the severity of the disease process but also to the antibiotic resistance. Acinetobacter species, particularly Acinetobacter baumannii is an important pathogen causing nosocomial outbreaks of infection in healthcare settings. Herein, we evaluated the biofilm forming ability of Carbapenem resistant Acinetobacter isolated from various clinical specimens.

Methods: A total of 109 phenotypically identified Acinetobacter isolates from different clinical specimens were studied, in which, Carbapenem resistance was determined as per the CLSI guidelines. Those isolates were then quantitatively assessed for their biofilm forming ability using the Microtitre Plate Assay.

Results: Of the 109 Acinetobacter isolates studied, 64.2% were Carbapenem resistant. Among them, 77.1% were biofilm formers. There was significant association seen between Carbapenem resistance and biofilm formation (p = 0.024). Odds ratio calculated was 2.6.

Conclusion: Our study showed that among the Carbapenem resistant strains of Acinetobacter, a significant number were biofilm producers. Further genetic analysis may provide a better understanding of the virulence, multidrug resistance and survival of the bacteria in the hospital environment.

Keywords: Acinetobacter, Carbapenem resistant, Modified Hodge Test, Combined Disc Test, Microtitre Plate Assay, Biofilm.

1. Doughari HJ, Ndakidemi PA, Human IS, Benade S. The ecology, biology and pathogenesis of Acinetobacter spp.: an overview. Microbes Environ 2011; 26(2):101–112
2. Mindolli PB, Salmani MP, Vishwanath G, Hanumanthapa AR. Identification and speciation of Acinetobacter and their antimimicrobial susceptibility testing. Al Ameen J Med Sci. 2010; 3:3459.
3. Perez F, Hujer AM, Hujer KM, Decker BK, Rather PN, et al. Global Challenge of Multidrug-Resistant Acinetobacter baumannii Antimicrob Agents Chemother. 2007; 51(10): 3471–84.
4. Bergogne-Berezin E, Friedman H, Bendinelli M, editors. Acinetobacter Biology and Pathogenesis: Springer; New York 2008.
5. Towner KJ. Clinical importance and antibiotic resistance of Acinetobacter spp. Proceedings of symposium held on 4-5 November 1996 at Eilat. Israel J Med Microbiol 1997; 46: 721-46.
6. European Centre for Disease Prevention and Control. Rapid risk assessment: Carbapenem- resistant Enterobacteriaceae. ECDC: 2016. Available from: http://ecdc.europa.eu/en/publications/Publications/carbapenem-resistant-enterobacteriaceae-risk-assessment-april-2016.pdf
7. Rodriguez-Bano J, Marti S, Soto S, Fernandez-Cuenca F, Cisneros JM, Pachon J, et al. Biofilm formation in Acinetobacter baumannii: Associated features and clinical implications. Clin Microbiol Infect 2008; 14:276-8.
8. Rao RS, Karthika RU, Singh SP, Shashikala P, Kanungo R, Jayachandran S, et al. Correlation between biofilm production and multiple drug resistance in imipenem resistant clinical isolates of Acinetobacter baumannii. Indian J Med Microbiol 2008; 26:333-7.
9. 2015. Performance standards for antimicrobial susceptibility testing; twenty second informational supplements. CLSI document M100-S25. Wayne PA: Clinical and Laboratory Standards Institute.
10. Sivasankari S, Senthamarai , Anitha C, Sastry A, Bhatt S, Kumudhavathi M S, et al. Phenotypic detection of carbapenem resistance in clinical isolates of Acinetobacter baumanii in Kanchipuram. Int J Appl Biol Pharm Technol 2014; 5(1): 50-53.
11. Modified Hodge Test for carbapenemase detection in Enterobacteriaceae. cdc.gov/HAI/pdfs/labSettings/HodgeTest_Carbapenemase_Enterobacteriaceae
12. Agrawal R, Sumana MN, Kishore A, Kulkarni M. Simple Method for Detection of Metallo – β–Lactamase Among Gram Negative Isolates. Online J Health Allied Scs. 2015; 14(3):6.
13. Badave, G. K. & Kulkarni, D. Biofilm producing multidrug resistant Acineto-bacter baumannii: an emerging challenge. J. Clin. Diagn. Res. 2015; 9: 8–10.
14. Raina D, Sharma N, Mahawal BS, Khanduri A, Pandita A. Speciation and antibiotic resistance pattern of Acinetobacter species in a tertiary care hospital in Uttarakhand. International Journal of Medical Research & Health Sciences 2016; 5(4): 89-96.
15. Singla P, Sikka R, Deep A, Seema, Chaudhary U. Pattern of antimicrobial resistance in clinical isolates of Acinetobacter species at a tertiary level health care facility in northern India. Journal of Evolution of Medical and Dental Sciences 2013; 2(2):159-165.
16. Shareek PS, Sureshkumar D, Ramgopala-krishnan, Ramasubramanian V, Ghafur K, Thirunarayanan MA.Antibiotic Sensitivity Pattern of Blood Isolates of Acinetobacter species in a Tertiary Care Hospital: A Retrospective Analysis. Am. J. Infect. Dis. 2012; 8 (1): 65-69.
17. Amudhan SM, Sekar U, Arunagiri K, Sekar B. OXA Beta-lactamase-mediated carbapenem resistance in Acinetobacter baumannii. Indian J Med Microbiol. 2011; 29(3):269–74.
18. Shivaprasad A, Antony B, Shenoy P. Comparative evaluation of four phenotypic tests for detection of metallo-beta-lactamase and carbapenemase production in Acinetobacter baumannii. J Clin Diagn Res. 2014; 8(5):DC05–DC08.
19. Manchanda V, Sanchaita S and Singh NP. Multidrug Resistant Acinetobacter. J Glob Infect Dis. 2010; 2(3):291–304
20. Bala M, Gupte S, Aggarwal P, Kaur M, Manhas A. Biofilm producing multidrug resistant Acinetobacter species from a tertiary care hospital : a therapeutic challenge. 2016; 4(7):3024–6.
21. Rodriguez-Bano J, Marti S, Soto S, Fernandez-Cuenca F, Cisneros JM, Pachon J, et al. Spanish Group for the Study of Nosocomial Infections (GEIH). Biofilm formation in Acinetobacter baumannii: Associated features snd clinical implications. Clin Microbiol Infect2008; 14:276-8.
22. Abdi-Ali A, Hendiani S, Mohammadi P, Gharavi S. Assessment of biofilm formation and resistance to imipenem and ciprofloxacin among clinical isolates of Acinetobacter baumannii in Tehran. Jundishapur J Microbiol 2014; 7(1): e8606.
23. Rong D, Chun G, Dan H, Ting-ting X, Yan Q. The correlation study on antimicrobial resistance and biofilm related genes in the clinical isolates of Acinetobacter baumannii. Chin Crit Care Med 2013; 25(8): 493-94.
24. Wroblewska MM, Sawicka-Grzelak A, Marchel H, Luczak M, Sivan A (2008) Biofilm production by clinical strains of Acinetobacter baumannii isolated from patients hospitalized in two tertiary care hospitals. FEMS Immunol Med Microbiol 53: 140–144.
25. Gurung J, Khyriem AB, Banik A, Lyngdoh WV, Choudhury B, Bhattacharyya P. Association of biofi lm production with multidrug resistance among clinical isolates of Acinetobacter baumannii and Pseudomonas aeruginosa from intensive care unit. Indian J Crit Care Med 2013; 17:214-8.

Banashankari G.S

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