Identification, Characterization and Antibiotic Susceptibility of Indoor Airborne Bacteria in Selected Wards of Hawassa University Teaching and Referral Hospital, South Ethiopia

Atmospheric pollution is one of the most pressing problems of our age. This pollution has now reached advanced level that poses a potential threat to the health and wellbeing of the population. Nosocomial infection (NI) is an infection occurring in a patient in a hospital or other health care facility in whom the infection was not present or incubating at the time of admission. One of the risk factors for such infection is bacterial contamination of hospital wards indoor air by bacteria. In view of this, the microbiological quality of air can be considered as a mirror of the hygienic condition for hospital wards. A cross sectional study was conducted from May to August 2011 in central triage, emergency, surgical outpatient, medical outpatient, gynecology and obstetrics, pediatrics, surgical inpatient and medical inpatient wards of Hawassa Teaching Referral Hospital to assess the bacteriological quality of indoor air and to determine the antibiotic susceptibility of the isolates. Air samples of the selected wards were collected using Settle Plate Method in the morning and in the afternoons and cultured aerobically. Of the 128 indoor air samples collected from the hospital rooms 124 (96.9%) were culture positive resulting in 153 isolate of nine spp/genera of bacteria. Gram negative and Gram positive bacteria accounted for 56.9 and 43.1% of the isolates respectively. The bacteria isolated were S. aureus (25.4%), Klebsiella spp. (24.8%), Proteus spp. (11.8%), coagulase negative streptococci (CNS) (10.5%), Serratia spp. (9.2%), Streptococci spp. (7.2%), E. coli (4.6%), Citrobacter (4.0%) and Enterobacter spp. (2.6%). No difference was observed in type and frequency of bacterial isolates among the different wards and between samples collected in the morning and in the afternoon (P >0.05). High level of antimicrobial resistance was observed among the isolates obtained in this study; 86.9% were resistant to 1 or more antimicrobials and 73.8% were multidrug resistant. Resistance was especially high against amoxicillin (64.9%) and penicillin (58.4%). Hospital management was advised to reduce foot trafficking and to periodically assess the quality of indoor air to identify and minimize/eliminate sources of microbial contamination.