Otoscope and Stethoscope: A Vehicle for Microbial Colonization, at Tikur Anbessa Specialized Referral Hospital, Addis Ababa, Ethiopia.

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Addis Ababa University


Background: Nosocomial infections (NIs) remain a significant cause of morbidity and mortality both in developed and developing countries. NIs is caused by the microorganisms that are commonly found around the hospitals. In the hospital environment, medical equipment's carried by HCWs such as otoscopes and stethoscopes may serve as the reservoir for microorganisms. Objectives: This study was undertaken to determine microbial colonization of otoscopes and stethoscopes used by HCWs at Tikur Anbessa Specialized Referral Hospitals, Addis Ababa, Ethiopia, between November 2011 and April 2012. Materials and Methods: 130 stethoscopes and 6 otoscopes were sampled from different health personnel of five wards. Cleaning trends of stethoscopes and otoscopes by HCWs were assessed through the prepared questionnaire. Swab sample was taken by rubbing the diaphragm and bells of stethoscopes as well as handles and tips of otoscopes with sterile cotton tip applicator moistened in sterile saline. The swabbed sample was inoculated immediately on blood agar and Sabouraud dextrose agar for bacterial and fungal growth respectively. Identification of bacteria were done using gram staining, colony morphology, biochemical tests include catalase and coagulase tests (for gram positive bacteria), oxidase test and API 20E (for gram negative bacteria). Germ tube test, LPCB staining, gram staining and thermo tolerant growth test were done for identification of fungal species. For bacterial isolates, antibiotic susceptibility test were done by disc diffusion method according to the preset criteria and the result were interpreted as susceptible, intermediate and resistance by measuring the growth inhibition zone. Results: From the total of 136 medical devices (6 otoscopes and 130 stethoscopes) sampled, 82(60.3%) were colonized with different species of bacteria (n=99) and fungi (n=12). From the total of bacterial colonization, gram positive bacteria accounted for 94(94.9%) where as gram negative bacteria accounted for 5(5.1%) and fungi accounted for 12(10.8%). Among the bacteria isolates, CoNS were dominated and of fungi, Candida albicans were dominated. Of the 130 stethoscopes sampled, 70(53.8%) showed bacterial colonization and 9(6.9%) were showed fungal colonization. Among different HCWs, 31(70.5%) of stethoscopes from resident medical doctors and also among the five wards, 25(71.4%) of stethoscopes from ICU were showed high rates of microbial colonization. Five (45.5%) and 74(62.2%) of stethoscopes that cleaned and not cleaned between patients examination respectively were showed microbial colonization. And also 60 (57.1%) and 19(76.0%) of stethoscopes that cleaned with disinfectant and not cleaned with any disinfectants respectively were showed microbial colonization. S.aureus and CoNS isolates were showed low level of resistance (<60%) for Oxacillin, Erythromycin, Penicillin G, Trimethoprim-sulphamethoxazole, Ampicillin, Chloramphenicol, and Ceftriaxone antibiotics. For Clindamycin and Vancomycin, S.aureus was showed 100% susceptible but CoNS were showed low level of resistance. Isolates of gram negative bacteria were showed intermediate level of resistance (60-80%) for Ampicillin, Erythromycin and Trimethoprim-sulfamethoxazole, and low level of resistance (<60%) for Chloramphenicol, Ceftriaxone, Ciprofloxacin and Nalidixic Acid, but 100% susceptible for Gentamicin. Conclusion: Otoscopes and stethoscopes might be a vehicle for both pathogenic and nonpathogenic microorganisms. Microbial colonization rate was reduced by regular cleaning of Otoscopes and stethoscopes. Clindamycin and Vancomycin antibiotics were effective against gram positive where as Gentamicin was effective against gram negative bacteria isolate from otoscopes and stethoscopes. Recommendations: Efforts should be directed towards standard cleaning strategy and continued re-evaluation of the microbial profile and their resistant patterns. In addition, health care workers should be informed that these devices might be act as a vehicle for microbial colonization.



Otoscope, Stethoscope, Microbial Colonization, Tikur Anbessa Specialized Referral Hospital, Ethiopia.