An Approach of Phenotypic Detection of Metallo-Beta Lactamase Producing Pseudomonas aeruginosa: A Study in Madhya Pradesh
Authors: Ramanath K , Sharma Munesh K. , Rajput Madhurendra S. , Navdeep  , Negi Sandeep , Bhate Viraj 
Published: August 2024

ABSTRACT

Introduction:
Antibiotic resistance in the last decade has recorded drastic changes in an increasing manner in nonfermenting bacterial groups of gram-negative bacilli including Ps. aeruginosa is a potent bacterial isolate or opportunistic nosocomial human pathogen. In recent decades, with improvements in antimicrobial therapy and diagnostic procedures have emerged multidrug resistant with beta lactamase to β-lactam antibiotics in presence of carbapenemases group of enzymes as metallo β-lactamases (MBL) are a major cause of concern. Due to its transferable character, it can hydrolyze almost all antibiotics. So, the study has conducted the detection of MBL isolates in hospital.

Materials and Methods:
In the study, 134 nonrepetitive clinical isolates of Pseudomonas spp. from the In Patient Department (IPD) patients attended to hospital from different clinical and isolates were confirmed in the department of microbiology and tested by the Kirby-Bauer disc diffusion method, which were screened for MBL production by disc synergy test as double-disc synergy test (DDST), combined-disc synergy test, and Modified Hodge test (MHT). The test was observed by a zone of inhibition of antibiotic with EDTA discs was ≥7 mm antibiotic disc alone as positive. MHT by the presence of a ‘cloverleaf shaped’ zone of inhibition was considered positive. Data were statistically analyzed and generated the graphs, whereas categorical variables (age and gender) were described in a descriptive way. Prevalence and percentage were used to establish an association of risk factors with carbapenem resistance strains.

Result:
A total of 134 Ps. aeruginosa was obtained from various clinical samples as 56 were found maximum in pus. Thirty nine bacterial isolates were found carbapenem resistant and in which 24 males (61.5%) were higher than 15 females (38.5%) in the 41-50 years age group. Carbapenem-resistant strains screened were for MBL production and found maximum by MHT test showed positive with meropenem (76.92%) and imipenem (71.79%). Isolates were found maximum in inpatients from surgical ward 45 (33.58%). Also, carbapenem-resistant isolates were found maximum from surgery (18). Four patients developed surgical site infections, had ulcerative lesions viz. traumatic, nondiabetic ulcer and from intensive care unit, 2 patients clinically identified as ventilated associated pneumonia (with COPD), 1 was immunocompromised with respiratory failure and COPD died in study.

Discussion:
Carbapenem resistant Ps. aeruginosa was found especially among critically ill patients. Isolates were found predominantly among males in the 41-50 years age group of patients. All 39 isolates were found resistant to meropenem, 32 (82.05%) bacterial isolates were resistant to both meropenem and imipenem where 7 (17.95%) isolates were found resistant to meropenem but sensitive to imipenem. MHT test was used to detect carbapenems activity but it does not give the confirmation of metal dependence of the carbapenems none of the phenotypic tests were optimal due to lower sensitivity or specificity. DDST has less channel of subjective variation, but combined-disc synergy test interprets more. The test between meropenem and meropenem with EDTA disc enhanced by diffusion method demonstrates the better synergy test (also for imipenem) and detection of carbapenem-resistant are not statistically significant [calculated P value is. 12 (P value >.05)]. The Minimum Inhibitory concentration (MIC) antibiotic susceptibility testing by E-test for imipenem and meropenem defines the use for the future. The surgical department found the highest prevalence may be due to the patient being treated by another hospital and was on third-line medication of cephalosporins. This may be due to higher comorbidity, invasive procedures, nonhealing ulcers after surgery, longer stay in the hospital, and excessive use of broad-spectrum antibiotics. The study was observed in economically weaker patients; seasonal trends of patient’s admission and due to rural area tertiary healthcare centers awaiting improvement of the facility which may associate admission avoidance by the patient.

Conclusion:
MBL production was identified as the resistant mechanism of resistance carbapenems group of drugs including another group of antibiotics; prevalence was found similar to other studies but the resistance to another group of antibiotics was found lower. Also, disc diffusion method was reliable for screening with a correlation of DDST or MHT. Our study was focused to improve hospital infection control by the prevalence of organisms and their related risk factors, which may help in care and treatment of patients after admission. Evaluation still needs to conclude a positive association as per our study. E-test–based testing and molecular detection were not done in all isolates.