Rapid identification of carbapenemases by CarbAcineto NP test and the rate of beta-lactamases among Acinetobacter baumannii from a teaching hospital

Morubagal Raghavendra Rao; Tejashree Anantharaj Urs; Vidyavathi B Chitharagi; Sowmya Shivappa; Rashmi Padmanabha Mahale; Ranjitha  Shankare Gowda; Kavya Shree

doi:10.18502/ijm.v14i2.9184

Morubagal Raghavendra Rao Department of Microbiology, JSS Medical College, JSSAHER, Mysore, India
Tejashree Anantharaj Urs Department of Microbiology, JSS Medical College, JSSAHER, Mysore, India
Vidyavathi B Chitharagi Department of Microbiology, JSS Medical College, JSSAHER, Mysore, India
Sowmya Shivappa Department of Microbiology, JSS Medical College, JSSAHER, Mysore, India
Rashmi Padmanabha Mahale Department of Microbiology, JSS Medical College, JSSAHER, Mysore, India
Ranjitha Shankare Gowda Department of Microbiology, JSS Medical College, JSSAHER, Mysore, India
Kavya Shree Department of Microbiology, JSS Medical College, JSSAHER, Mysore, India

DOI: https://doi.org/10.18502/ijm.v14i2.9184

Keywords: AmpC; Beta-lactamase; Carbapenemase; Extended spectrum beta lactamase

Abstract

Background and Objectives: Acinetobacter baumannii has emerged as a major organism accounting for hospital acquired infections particularly in intensive care units. Due to production of different kinds of beta lactamases these bacteria have developed drug resistance rendering the treatment of such infections very difficult and expensive. Rapid identification of A. baumannii producing such beta-lactamases is the need of the hour in reducing morbidity and mortality associated with A. baumannii infections.

Materials and Methods: A. baumannii was isolated from clinical samples like endotracheal aspirates, sputum, urine, exu- dates using standard culture techniques. Identification and drug sensitivity was done using Vitek 2 system. All the isolates were subjected to detection of ESBLs using phenotypic confirmatory test, plasmid mediated AmpC beta- lactamase by AmpC disc test, Carbapenemase production by CarbAcineto NP Test and Modified hodge method.

Results: 149 A. baumannii isolates were analysed for antimicrobial susceptibility and various beta-lactamase production. Results were evaluated for statistical significance using Chi-Square and P value. 81.8% of isolates were from male patients with majority of them above 50 years of age. 88.5% of samples were from ventilator associated pneumonia patients. 83.8% of isolates were sensitive to tigecycline. Only 10% to 12% of isolates were sensitive to carbapenems. 23.4% of isolates were ESBL producers and 46.9% of them were AmpC producers. Modified Hodge test method identified 63.7% of A. baumannii as carbapenemase producers where as CarbAcineto NP test identified 63% and exibiting 94.74% sensitivity, 93.22% specificity when compared to Modified Hodge test.

Conclusion: Multidrug resistant Acinetobacter spp. is on the rise. Present study showed that high percentage of drug resis- tance in A. baumannii could be due to production of ESBLs, AmpC and carbapenemases. Among all beta lactamases car- bapenemase producers are more and quickly raising in A. baumannii. Rapid, cost effective assay which can be adopted in all clinical laboratories is critical to prevent their further transmission particularly in hospital environment.