Hospital-related factors associated with multidrug resistant organism acquisition : a cross-control study

Date of Award


Document Type


Degree Name

Master of Science in Epidemiology & Biostatistics (MSc Epidemiology & Biostats)


Community Health Sciences


Antimicrobial resistance was recently declared a major global problem by World Health Organization. Such alarming rates of prevalence and transmission pose a public health problem as there are extreme limitations in the choice of antibiotics for treating patients with these infections. Association of modifiable hospital-related factors such as average ward/unit length of stay, understaffing and bed occupancy rates to multidrug-resistant organism acquisition remains unexplored. We aimed to determine the association of hospital-related factors with multidrug-resistant organism acquisition in a tertiary-care hospital in Karachi, Pakistan. Methods: We conducted a case-control study at Aga Khan University Hospital, Karachi, Pakistan between January 2016 and December 2016. Cases included patients with culture-proven multidrug-resistant organism after more than three days of hospitalization, while controls did not have a multidrug-resistant organism in any culture specimen. Data was collected on a structured proforma from hospital records for patient demographics and clinical data including admission diagnosis, type of infection, exposure to invasive devices and use of antibiotics. Ward/unit length of stay was the main hospital factor, defined as number of patient days per monthly number of patients in ward unit. Other hospital ward related risk factors included bed occupancy rate, 24 hour nurse to patient ratios and hand hygiene compliance rates. Multilevel logistic regression was performed to assess the individual and joint effects of patientand hospital-related variables. Results: 154 cases and 302 controls were included in the analysis. The odds of acquiring multidrug-resistant organism increased with the length of stay (OR 1.50, 95%CI 1.04-2.17) controlling for other factors. Among the patient related factors, MDRO acquisition was associated with presence of nasogastric tube, (OR 4.31, 95%CI 2.44-7.91), use of (OR 10.07, 95%CI 5.19-19.53), use of glycopeptide (OR 3.06, 95%CI 1.61-5.83), use of beta lactam/beta lactam inhibitor (OR 2.60, 95%CI 1.46-4.63) and central nervous system disease on admission (OR 3.75, 95%CI 1.65-8.51). MDRO acquisition decreased with increased hand hygiene compliance rate (OR 0.96, 95%CI 0.92 — 0.99). The intra class correlation was 0.94. Conclusion: Our study demonstrates that average length of stay in an individual ward may be a modifiable hospital-related risk factor for multidrug-resistant organism acquisition. MDRO acquisition is associated with empiric use of broad spectrum antibiotics (Carbapenem, Glycopeptide and Beta-lactam/beta lactamase inhibitor) whereas hygiene compliance is protective against MDRO acquisition. We recommend reducing average length of stay in wards and promoting antimicrobial stewardship and hand hygiene compliance in hospitals.

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