Isolation and Characterization of Haemophilus Ducreyi Strains from Children with Cutaneous Lesions in Yaws Endemic Regions, Ghana

Abstract

Recent discovery of cutaneous H. ducreyi has complicated the epidemiology of Yaws in endemic countries. Yaws and H. ducreyi ulcers are clinically indistinguishable from each other and some other causes of skin ulcerations. The aim of the study was to isolate and characterize H. ducreyi strains from lesions of children in yaws-endemic areas. Symptomatic patients were first screened with Dual Path Platform (DPP-RDT) Syphilis Screen & Confirm test kit (Chembio, Medford, New York) for yaws. Lesion exudates were tested by culture for H. ducreyi and real-time multiplex PCR assays were used to identify T.p subsp. pertenue DNA and H. ducreyi DNA. Azithromycin (AZT) resistance markers were screened for in T.p subsp. pertenue PCR positives. Bacterial 16S rRNA gene was amplified and sequenced to detect the presence of other pathogenic bacteria. Patient data showed 84 of 115 more males than females, mean aged 10 years. Eighty-seven percent had a clinically apparent skin lesion with few having skin conditions clinically consistent with yaws. Dual DPP-RDT positives were 64 while dual DPP-RDT negatives were 51. Of 60 bacteria culture positives obtained from symptomatic patients, 7 yielded a definitive diagnosis of H. ducreyi. Isolated cutaneous H. ducreyi strains by their appearance in colony morphology and colour differed compared to genital H. ducreyi strain, HD 35000. Out of 112 samples, 32 were H. ducreyi PCR positive, 11 were T.p subsp. pertenue PCR positive, while 1 had both pathogens. An A2058G point mutation in the 23S rRNA gene of T.p subsp. pertenue indicates resistance to AZT. A total of 69 of 112 samples with unknown aetiology could possibly be any of these bacterial species; Fusobacterium necrophorum subsp. funduliforme, Catonella morbi and Staphylococcus capitis subsp. capitis amongst others. This study suggest the need to isolate bacterial species associated with cutaneous lesions to screen for other antibiotics to be used as a combination therapy with AZT during mass drug administration (MDA) activities.