Are we missing the silver lining of COVID-19 pandemic: An analytical study to determine effects of three COVID-19 peaks on antimicrobial susceptibility of Staphylococcus aureus isolates.

Background: Given the evolving nature of COVID-19, for better understanding of its effect on antimicrobial resistance of Staphylococcus aureus (S. aureus), it becomes crucial that we follow the resistance patterns across different surges of COVID-19 cases. Methods: This prospective surveillance study extended over two years from January 2020-March 2022 and was conducted in a healthcare center of North India. Susceptibility patterns of Staphylococcus aureus during January-March 2020 were considered as prepandemic patterns. Processing of clinical specimens, identification of S. aureus, and in-vitro antibiotic susceptibility testing were performed in accordance with standard microbiological testing procedures and Clinical Laboratory Standard Institute guidelines. Results: Lowest prevalence (38.9%) of Methicillinresistant S. aureus was reported during January-March 2021 and July-September 2021. More than 50% S. aureus isolates were susceptible to linezolid, cotrimoxazole, tetracycline, and gentamicin in January-March 2020. In January-March 2021, ≥50% of S. aureus isolates from clinical specimens were additionally susceptible to clindamycin and erythromycin. Antibiotic agents of linezolid, tetracycline, clindamycin, and cotrimoxazole were susceptible in ≥50% of S. aureus isolates in January-March 2022. Conclusions: This study reveals a sharp decline in overall resistance to commonly prescribed antibiotic agents for S. aureus isolates after first peak of COVID-19 cases. However, same trend was not observed in subsequent peaks and probably we are approaching the same resistance levels that were seen prior to COVID-19 pandemic.

Colistin Susceptibility Testing by Colistin Broth Disk Elution MIC Method among Carbapenem-resistant Gram-negative Blood Culture Clinical Isolates in a Tertiary Care Setting, East Delhi, India.

Background: Antibiotic resistance is a growing concern for bloodstream infections (BSIs), especially with the emergence of multidrug-resistant (MDR) gram-negative bacteria. In this study, we aimed to assess the pattern of colistin susceptibility using the colistin broth disc elution (CBDE) method among carbapenem-resistant gram-negative clinical isolates from blood cultures in a high burden tertiary healthcare setting in East Delhi. Methods: A total of 106 carbapenem-resistant gram-negative clinical isolates were tested. The most common isolates were Klebsiella pneumoniae, Escherichia coli, Enterobacter species, and Klebsiella oxytoca by CBDE method. Result: All the carbapenem resistant gram-negative bacterial blood culture isolates showed intermediate colistin susceptibility. This was statistically significant by chi-square test (p<0.5). Conclusion: This study highlights the need to monitor colistin resistance trends in the face of increasing antimicrobial resistance. Accurate surveillance of emerging colistin resistance is crucial for effective management of BSIs caused by carbapenem-resistant gram-negative bacteria.