Impact of the COVID-19 Pandemic on Laboratory Diagnosis of Bacterial Infections in Teaching Hospitals in Ogun State

The COVID-19 pandemic disrupted healthcare systems globally, with significant secondary impacts on the diagnosis and management of bacterial infections due to resource diversion, reduced patient healthcare-seeking behaviour, and laboratory workflow disruptions. This retrospective interrupted time series study examined the impact of the pandemic on the volume and diagnostic outcomes of bacteriological laboratory testing in two teaching hospitals in Ogun State, South West Nigeria. Monthly records of bacteriology test requests, specimen types, culture positivity rates, and antibiogram results were extracted from laboratory information systems for 36 months: 12 months pre-pandemic, 12 months during peak pandemic disruption, and 12 months post-restriction. Subgroup analyses compared blood culture, urine culture, and wound swab culture trends separately. Results showed a 41 percent reduction in total bacteriology test requests during the peak pandemic period compared to the pre-pandemic baseline. Blood culture positivity rates paradoxically increased from 22 to 31 percent during the pandemic, suggesting selective testing of more severely ill patients. Septicemia-associated mortality recorded in clinical records increased by 38 percent during the pandemic period. Antibiogram trend data showed emergence of increased carbapenem resistance during the pandemic, potentially linked to increased broad-spectrum empirical prescribing under diagnostic uncertainty. These findings document significant pandemic-related collateral damage to bacterial infection diagnostics and resistance trends in Ogun State and recommend resilience-focused laboratory strengthening strategies. Keywords: COVID-19 pandemic, bacteriology laboratory, diagnostic disruption, antimicrobial resistance, Ogun State.