Isolation Frequency of Fluconazole-Resistant Candida Species From Cockroaches: A Cross-Sectional Study From a National Hospital in Dar es Salaam, Tanzania

Background: Cockroaches are common pests in homes and hospitals. They cause allergic reactions in some individuals and are potential vectors for various infectious pathogens. The study investigated the extent to which hospital cockroaches act as vectors and reservoirs of medically important fungal pathogens on their external surfaces. Methods: Cockroaches were captured from the selected hospital locations including the burn unit, adult surgical wards, pediatric oncology wards, intern hostel kitchen, and the central kitchen of a national referral teaching hospital in Tanzania. Normal saline washings from the external surface of cockroaches were cultured on standard mycological media to facilitate isolation and identification of medically important molds and yeasts. The susceptibility of Candida species isolates to fluconazole was tested using the Clinical and Laboratory Standards Institute (CLSI) M27-A3 microdilution method. Results: A total of 69 cockroaches were captured from various hospital sites between February and April 2017. All cockroaches captured were shown to carry medically important fungi. A total of 956 medically important fungi were isolated; 554 (57.9%) were of Candida species, 222 (23.2%) were of Aspergillus species, 30 (3.1%) were of Cladosporium species, 17 (1.8%) were of Rhizopus species, 11 (1.2%) were of Geotrichum species, nine (0.9%) were of Penicillium species, seven (0.7%) were of Alternaria species, six (0.6%) were of Fusarium species, three (0.3%) were of Mucor species, and 97 (10.1%) were of other species. Of the Aspergillus species, Aspergillus fumigatus (111, 50.0%) was the most commonly isolated, followed by Aspergillus niger (35, 15.8%) among the Aspergillus isolates. Out of the 103 selected isolates, 18 (17.5%) of the Candida isolates normally not intrinsically resistant to fluconazole demonstrated resistance to this drug. Resistance was most frequently found in Candida parapsilosis (3, 30%), Candida pseudotropicalis (10, 23.8%), and Candida glabrata (2, 18.2%). The isolates with the least proportion of resistance to fluconazole were Candida albicans (2, 6.3%). Conclusion: Cockroaches from this hospital may act as reservoirs of medically important opportunistic fungi exhibiting resistance to fluconazole.