Title : Temporal shifts in antibacterial susceptibility during the phased expansion of a tertiary care centre
Abstract:
Background: Antimicrobial resistance (AMR) is recognised as one of the top ten global public health threat by World health organisation. Inappropriate and misuse of antibiotics play a major role in the emergence of multidrug resistant organisms which ultimately leads to treatment failure, prolonged hospital stays, increased healthcare cost and higher morbidity and mortality. Documentation of antimicrobial resistance in the early stages of hospital establishment gives a unique opportunity to generate a baseline antibiogram to guide empirical therapy.
Methods: This retrospective observational study was conducted in the Department of Microbiology at All India Institute of Medical Sciences (AIIMS), Jammu, India, over a period of 18 months. This study period was divided into three phases: Phase I, (outpatient services ) Phase II, (introduction of inpatient services) ; and Phase III, full hospitals services. All clinically significant culture-positive bacterial isolates from different samples like blood, respiratory samples, urine, and sterile body fluids during the above-mentioned period were included in the study. Identification of bacteria was done using an automated identification system (VITEK® 2, bioMérieux), and antibacterial susceptibility testing (AST) was performed and interpreted as per CLSI guidelines, M34, 100th Edition. Trends in the susceptibility of different organisms were compared across the three phases.
Results: Of 14,966 samples received during the entire study period, 2681 (17.9%) samples were culture positive. A total of 330 isolates recovered during Phase I, 933 isolates in Phase II, and 1,418 isolates in Phase III. Gram negative organisms (80.9%) were predominantly isolated during the entire study period, with Escherichia coli and Klebsiella pneumoniae being the most frequently isolated, followed by Pseudomonas aeruginosa and Acinetobacter baumannii. Reduced susceptibility to third-generation cephalosporins, fluoroquinolones, and β-lactam–β-lactamase inhibitor combinations were observed in Phase II and III compared to Phase I. With respect to carbapenems, an overall 23.2% of all the isolates were resistant to either meropenem or imipenem with a rising trend from 17.5% during Phase Ito 25.3 in Phase III. In Gram positive organisms, the incidence of methicillin-resistant Staphylococcus aureus (MRSA) increased from 66.7 in Phase I to 80.4% in Phase III. These changes in the susceptibility pattern corresponded with the expansion of hospital services.
Conclusion: The phased expansion of hospital services was associated with a significant increase in the incidence of carbapenem-resistant Enterobacterales (CRE) and MRSA. Early microbiological surveillance provides the essential baseline data of antimicrobial resistance to guide empirical therapy and to strengthen antimicrobial stewardship strategies.
