Microbiological assessment of indoor air quality at different sites of a tertiary hospital in South‑South Nigeria

Abstract

Background: The risk of nosocomial infection is increasing due to the increasing number of patients with immune depression. Good ventilation is one of the methods used to reduce the ambient air levels of the causative agents, but this is rarely observed in Nigeria as hospital designs used to shut out the inclement weather in temperate countries are copied without many modifications, and without adequate provisions to constantly power the mechanical ventilation mechanisms. This study tested the microbiological air quality at different areas of the University of Port Harcourt Teaching Hospital to ascertain the levels of airborne bacteria and fungi in the ambient air.

Methods: The study was carried out in July 2015 in randomly selected inpatient wards, outpatient clinics, and clinical laboratories of the hospital. The assessment was carried out by exposing Petri dishes containing the appropriate culture media for about 30 min at a convenient place in each of the nine study sites. Thereafter, the plates were covered and immediately transferred to the laboratory for incubation at 37°C, for 24–48 h, for bacteria; and at room temperature, for 5–7 days, for fungi. The number and types of bacteria and fungi in the cultures were determined at the end of the incubation period.

Results: There were detectable bacteria and fungi in the ambient air of all the study sites. The mean bacterial count ranged from 9.5 colony forming unit per cubic meter (CFU/m3) in the urology ward to 199.33 in the HIV clinic, with a mean of 80.0 CFU/m3, while the mean fungal count ranged from 10.5 CFU/m3 in the surgery outpatient clinic (SOC) to 23.5 in the Anatomical Pathology Laboratory (APL), with a mean of 16.9 CFU/m3. Staphylococcus and  Streptococcus were  the most common bacteria in the SOC; Klebsiella  was  predominant in the immunization clinic; Escherichia coli were the most common in the APL, while bacillus was most frequently isolated in the gynecology ward. The fungi cultured from the study sites include Aspergillus, Penicillium, Fusarium, Trichophyton, Candida, and Rhizopus. Unlike the bacteria count, the fungal count increased in all the study sites at the end of the working day.

Conclusion: The number and types of bacteria and fungi cultured from the study sites have the potential to cause ill health. Corrective actions are therefore needed.