Nyirenda, T. | Search bioRxiv

bioRxiv2026

Assessing Bacterial contaminants on hospital devices at Zomba Central Hospital Intensive care Unit (ICU) and Theatre.

Hospital devices in intensive care unit (ICU) and theatre settings are prone to bacterial contamination, posing a major risk to patient safety. No previous study has been conducted at Zomba Central Hospital (ZCH) to assess such contamination. This study aimed to determine the prevalence and types of bacteria contaminating ICU and theatre devices, evaluate the effectiveness of cleaning protocols, and assess healthcare workers knowledge on infection control. A cross-sectional study involving 25 hospital devices and 30 healthcare workers was conducted. A self-administered questionnaire assessed staff knowledge and perceptions, while swabs were collected from devices before and after cleaning for culture and antimicrobial susceptibility testing. Of the 25 swabs collected, 72.0% were contaminated before cleaning, decreasing significantly to 36.0% after cleaning (p = 0.049). Gram-positive bacteria predominated (69.0%), with ventilators being the most contaminated devices. Multidrug resistance was detected in Extended Spectrum Beta Lactamase (ESBL) producing Klebsiella pneumoniae, Enterobacter spp., and carbapenem-resistant Serratia marcescens. Although most staff acknowledged the importance of infection prevention (93.3%), knowledge of bacterial contaminants (73.3% low) and recommended cleaning methods (90.0% low) was poor. Lower cadre roles (OR = 0.30, p = 0.020) and lower education levels (OR = 4.87, p = 0.032) were significantly associated with reduced knowledge. The study concludes that ICU and theatre devices at ZCH are contaminated with diverse bacterial species, including multidrug-resistant strains. While existing cleaning protocols significantly reduce contamination, enhanced staff training and standardized cleaning procedures are essential to ensure aseptic hospital environments. Keywords: ICU, Theatre, Bacterial contamination, Infection prevention, Multidrug resistance, Zomba Central Hospital.

microbiology↗

bioRxiv2019

African Salmonella Typhimurium sequence type 313 lineage 2 evades MAIT cell recognition by overexpressing RibB

Mucosal-associated invariant T (MAIT) cells are a subset of innate T lymphocytes activated by bacteria that produce vitamin B2 metabolites. Mouse models of infection have demonstrated a role for MAIT cells in antimicrobial defence. However, proposed protective roles of MAIT cells in human infections remain unproven and clinical conditions associated with a selective absence of MAIT cells have not been identified. We report that typhoidal and non-typhoidal S. enterica strains generally activate MAIT cells. However, African invasive disease-associated multidrug-resistant S. Typhimurium sequence type 313 lineage 2 strains escape MAIT cell recognition through overexpression of ribB, a bacterial gene that encodes the 4-dihydroxy-2-butanone 4-phosphate synthase enzyme of the riboflavin biosynthetic pathway. This MAIT cell-specific phenotype did not extend to other innate lymphocytes. We propose that ribB overexpression is an evolved trait that facilitates evasion from immune recognition by MAIT cells and contributes to the invasive pathogenesis of S. Typhimurium sequence type 313 lineage 2 in vivo.

immunology↗