Diagnostic Characterisation of Various Phenotypic Methods for Class-A Extended Spectrum of β-Lactamase among Multidrug Resistant Pseudomonas Aeruginosa Isolated from Diabetic Patients

Abstract

Introduction: Pseudomonas aeruginosa often causes nosocomial infection, especially in high risk group patients like diabetics. It shows a high degree of resistance to broad spectrum of antibiotics due to its high adaptabtibility in hospital settings, so their infections are difficult to treat. Extended Spectrum β-Lactamase (ESBL) enzymes confer resistance to most of the β-lactam antibiotics, including penicillin, cephalosporins and monobactams. Aim: To identify ESBL producing strains among Multidrug Resistant (MDR) Pseudomonas aeruginosa isolated from diabetes patients using various phenotypic methods with their performance characteristics. Materials and Methods: An observational descriptive crosssectional study was conducted in the Department of Microbiology at Sawai Man Singh Medical College, Jaipur, Rajasthan, India, from April 2017 to March 2019. Various clinical samples received from diabetic patients were cultured and P. aeruginosa were identified as per standard protocol. Antimicrobial susceptibility testing was done according to Clinical and Laboratory Standards Institute (CLSI) guidelines. ESBL producing MDR P. aeruginosa was detected by using standard Epsilometer test (E test), Phenotypic Confirmatory Disc Diffusion Test (PCDDT) and Double Disc Synergy Test (DDST). Test characteristics sensitivity, specificity, Positive Predictive Value (PPV), Negative Predictive Value (NPV) and accuracy were calculated. Kappa coefficient was used to show diagnostic agreement between the tests. Results: A total 430 clinical samples were received from diabetic patients, out of 430, 72 (16.7%) P. aeruginosa were recovered. Multidrug resistance was exhibited by 34 isolates out of 72 P. aeruginosa strains. Out of 34 MDR strains, 10 (29.4%) were found ESBL producers by PCDDT, 9 (26.47%) by DDST while 10 (29.4%) were found positive by E test. Sensitivity, specificity and accuracy for PCDDT was found 90%, 95.8% and 94.1% respectively and ‘almost perfect agreement’ was observed with E test. Conclusion: Magnitude of multidrug resistant strains was found 47.22% among P. aeruginosa isolated from diabetic patients which is an alarming sign. The ESBLs were found in 29.4% isolates. So, screening of ESBLs with the use of simple test like PCDDT in Pseudomonas aeruginosa will direct us for treatment option of suitable antibiotic regimens in diabetic patients and to prevent the spread of drug resistant organisms in hospitals.