Antibiotic susceptibility and genotyping of Mycobacterium avium strains that cause pulmonary and disseminated infection [PublishAheadOfPrint]

Mycobacterium avium subsp. hominissuis (MAH) causes mainly disseminated infection in immunocompromised hosts, such as individuals with human immunodeficiency virus (HIV) infection, and pulmonary infection in immunocompetent hosts. However, many aspects of the different types of MAH infection remain unclear. We examined antibiotic susceptibility and genotype in MAH isolates from different hosts by performing drug susceptibility testing using eight antibiotics (clarithromycin, rifampicin, ethambutol, streptomycin, kanamycin, amikacin, ethionamide, and levofloxacin) and variable number tandem repeats (VNTR) typing analysis for 46 isolates from the sputa of HIV-negative patients with pulmonary MAH disease without previous antibiotic treatment and 30 isolates from blood of HIV-positive patients with disseminated MAH disease. Interestingly, isolates from pulmonary MAH disease patients were more resistant to seven drugs except for rifampicin compared with isolates from HIV-positive patients. Moreover, VNTR typing analysis showed that the strains examined in this study were roughly classified into three clusters, and the genetic distance from a reference strain 104 in isolates from pulmonary MAH disease patients was statistically different from that in isolates from HIV-positive patients (p = 0.0018), suggesting that MAH strains that cause pulmonary and disseminated disease have genetically distinct features. Significant differences were noted in susceptibility for seven drugs except for ethambutol among the three clusters. Collectively, these results suggest that an association between types of MAH infection, drug susceptibility, and VNTR genotypes and the properties of MAH strains associated with the development of pulmonary disease are involved in higher antibiotic resistance.

http://ift.tt/2EmzJFL