Department: Applied Microbiology And Brewing
Ahuocha, Pauline Amaka
Anyamene, C. O.
Cutaneous mycoses caused by dermatophytic and non-dermatophytic fungi are highly contagious and represent significant public health problem in Nigeria and the world at large. The infection among rice farmers had not received much attention, hence, the prevalence of cutaneous mycoses among rice farmers in Parts of Ebonyi State and antifungal activity patterns of locally used herbs were studied. A total of 2130 rice farmers were randomly selected and screened for cutaneous mycoses. Hair fragments, skin and nail scrapings were collected from 182 rice farmers that presented with lesions suggestive of the infection using sterile scissors and scalpels. The samples were examined by direct microscopy using 5% KOH and cultured on Sabouraud dextrose agar supplemented with 0.05mg/ml chloramphenicol and 0.5mg/ml cycloheximide and incubated at 27oC for 4 weeks. The fungal isolates were identified by macroscopic and microscopic methods, and confirmed by molecular analysis. The ability of the isolates to secrete extracellular virulence enzymes was screened on solid media. Phytochemical screening of five medicinal plants: Azadirachta indica, Cymbopogon citratus, Emilia sonchifolia, Senna alata and Senna occidentalis; used by the farmers to treat the infection was carried out. The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of the plant extracts were evaluated using broth microdilution method and spread plate methods respectively. Terbinafine (125 mg) oral granules were used in the study as quality control antifungal agent. Demographic data and factors influencing the infection were obtained through questionnaires and analyzed using analysis of variance (ANOVA) at p<0.05 significant level with SPSS version 22. A total of 197 fungal isolates were recovered and comprised of 54 (27.41%) dermatophytes and 143 (72.59%) non-dermatophytes. Dermatophytes isolated included Trichophyton tonsurans 23 (11.68%), T. mentagrophytes 14 (7.11%), T. rubrum 7 (3.55%), T. soudanense 5 (2.54%), Microsporum gypseum 3 (1.52%) and M. canis 2 (1.01%) while non-dermatophyte species isolated included Aspergillus flavus 64 (32.49%), A. tamarii 41 (20.81%), A. nomius 30 (15.23%) and Candida albicans 8 (4.06%). The overall prevalence rate of the infection among the rice farmers was 182 (8.54%). Age, gender, educational status and family size of the farmers and their interactions with domestic animals/pets influenced the distribution of the fungal species. Out of 182 rice farmers screened, the age-group 16-26 years were most infected with the infection 71 (39.01%), followed by 39 (21.43%) between the age-group 27-37 years and a decline between the age-group 49-59 years 15 (8.24%). The females were more infected 144 (79.12%) than the males 38 (20.88%). The infection among the females was found to be significant (P<0.05). Among the skin infections observed in the study areas, tinea capitis 76 (3.57%) was the most predominant type of infection followed by tinea ungium (onychomycosis) 59 (2.77%) and tinea corporis 47 (2.20%). Highest keratinase (23 mm), protease (24 mm), lipase (22 mm) and collagenase (17 mm) activities were observed in T. rubrum while the highest xylanase (17 mm) and cellulase (22 mm) activities were observed in T. tonsurans and T. mentagrophytes respectively. Phytochemical screening of the medicinal plants used in this study showed that they contained some metabolites like flavonoids, alkaloids, saponins, tannins, phenols, glycosides, terpenoids and steroids. The range of MIC for n-hexane, chloroform, petroleum ether and hot water extracts of the medicinal plants against the fungal isolates tested was 2 - 15 µg/ml, 8 - 32 µg/ml, 4 - 18 µg/ml and 10 - 32 µg/ml respectively. Both dermatophytes and non-dermatophytes species isolated were susceptible to the plant extracts used in the study. The dermatophyte species were less susceptible to hot water extract. Minimum fungicidal concentration (MFC) values ranged from 4 - 32 µg/ml. The most significant MFC (4 µg/ml) was observed in n-hexane extracts of C. citratus and S. alata. The comparative results of antifungal susceptibility patterns of the various isolates to examined plant extracts indicated that the sensitivity to terbinafine (2 µg/ml) by the different species was higher than the plant extracts (4 µg/ml) with significant difference (P<0.05). These plant materials should be harnessed as they hold promising potential source of new drugs for the management and treatment of cutaneous mycoses.