Prevalence of cases of amebic liver abscess in a tertiary care centre in India: A study on risk factors, associated microflora and strain variation of Entamoeba histolytica

Amebiasis, caused by Entamoeba histolytica (E. histolytica), is a significant cause of morbidity and mortality in developing countries. Mortality due to amebiasis is mostly by extra intestinal infections, amebic liver abscess being the most common one. This study was conducted to determine the current epidemiological status, risk factors, associated microflora and strain variation of E. histolytica causing liver abscesses. A total of 115 liver abscess cases comprising of 107 (93%) males and 8 (6.9%) females were included in the study. Microscopic examination of pus samples from the abscesses and species discrimination using nested multiplex PCR showed the presence of E. histolytica in 101 (87.5%) cases. Data collected by face to face interviews using a pre tested questionnaire suggested intake of untreated drinking water (ORs: 6.4, p = 0.002), habit of alcohol consumption (ORs: 4.0, p = 0.019) and lack of urban services (ORs: 0.08, p = 0.017) to be major risk factors associated with E. histolytica infections. The study of associated bacterial flora through aerobic culture of liver aspirates and conventional PCR for detection of anaerobes revealed the presence of Fusobacterium (19, 25.5%), Peptococcus (19, 25.5%), Prevotella (18, 24.3%), Bacteroides (8, 10.8%), Staphylococcus aureus (3, 4%), Escherichia coli (2, 2.7%), Peptostreptococcus (2, 2.7%), Clostridium (2, 2.7%) and Klebsiella pneumoniae (1, 1.3%). Further to study the clonality, genotyping of E. histolytica targeting six tRNA-linked polymorphic STR loci (A-L, D-A, N-K, R-R, STGA -D and S-Q) was carried out which showed the presence of 89 different genotypes in the liver aspirate samples. The findings highlight the high prevalence of genetically diverse E. histolytica from the liver abscess cases in this geographical region. Low socio-economic status and habit of alcohol consumption were important predictors of amebic liver abscess.