Non-tuberculous mycobacteria isolated from slaughter pigs in Mubende district, Uganda

Abstract

BackgroundThe importance of infections caused by non-tuberculous mycobacteria (NTM) in animals and humans has gained considerable recognition during the past few years. In the developed world, where pig production is extensively practiced, studies on mycobacterial infections and related control strategies have received increasing attention. The infections are reported to be caused by a wide spectrum of NTM. Unfortunately, these infections have been less recognized in sub-Saharan Africa owing to lack of awareness and systematic studies. In this study we aimed at isolating and identifying species of mycobacteria involved in causing infections in slaughter pigs in Mubende district of Uganda. Furthermore we wanted to identify factors associated with infection prevalence in the study area.MethodsA total of 363 lymph nodes were collected and cultured for the presence of mycobacteria. Isolates were identified by 16S rDNA gene sequencing. A questionnaire survey was administered to identify production related factors associated with infection prevalence. Data were assembled and analysed using descriptive statistics and mixed effects logistic regression analysis.ResultsMycobacteria were detected in 39 % (143/363) of the examined lymph nodes, 63 % (59/93) of lymph nodes with gross lesions typical of mycobacteriosis and 31% (84/270) of lymph nodes with no visible lesions. Nineteen per cent of the isolated mycobacteria were identified as Mycobacterium (M) avium, of these 78% and 22% were M. avium sub sp. Hominissuis and avium respectively. Other mycobacterial species included M. senuense (16%), M. terrae (7%) and M. asiaticum (6%). This study found free range systems (OR = 3.0; P = 0.034) and use of water from valley dams (OR = 2.0; P = 0.049) as factors associated with high prevalence of mycobacteria in slaughter pigs.ConclusionsThis study demonstrated a high prevalence of NTM infections among slaughter pigs in Mubende district of Uganda. M. avium was the most prevalent of all NTM isolated and identified. Free range system of pig management and valley dam water were the most significant factors associated with NTM prevalence in Mubende district. These findings could be of a major public health concern given that it is in a predominantly pork consuming population with 18% HIV/AIDS prevalence. Therefore, stringent post-mortem inspection at the slaughter houses is of paramount importance to reduce human exposure.

Microbiomes of Unreactive and Pathologically Altered Ileocecal Lymph Nodes of Slaughter Pigs

“…It should be kept in mind that Mycobacteria also could be detected in ICLN groups other than granulomatous ICLNs in very low abundance, indicating a risk even if no granulomatous pathology can be observed in ICLNs. A similar observation was recently described in a study where 31% of Mycobacterium-positive lymph nodes of slaughter pigs did not show any visible lesions (56). This is interesting, considering that Mycobacteria are usually diagnosed only during postmortem examination in the slaughter process (57,58).…”

Mycobacterium bovis infections in slaughter pigs in Mubende district, Uganda: a public health concern

“…Routine abattoir meat inspections is the only economically feasible food safety tool that can be used in resource limited settings [10], however routine inspection is reported to have a low sensitivity for detecting tuberculosis lesions [16,17]. A recent study on slaughter pigs in Uganda also revealed that up to 31% of slaughtered pigs without visible lesions were harbouring non-tuberculous mycobacteria [18]. The sensitivity of routine inspection is reported to be affected by the frequency, dispersion and size of the lesions in addition to abattoir-environment factors like lighting and speed of flow system [19].…”

“…Earlier studies have characterised isolates of M. bovis from cattle and humans in the cattle corridor, revealing identical spoligotypes [22,23]. There are reports documenting the prevalence of non-tuberculous mycobacteria from slaughtered pigs in the Mubende district [18,24], but the role of pigs in the epidemiology of M. bovis had not been explored. This study was thus aimed at contributing to the knowledge of the epidemiology of M. bovis infections in Uganda, by investigating the occurrence and molecular characteristics of M. bovis from slaughter pigs, and by comparing these isolates with M. bovis detected from humans and cattle in earlier studies.…”

Draft Genome Sequence of Mycobacterium asiaticum Strain DSM 44297

“…M. asiaticum has been isolated in monkeys (3) and pigs (4). In humans, M. asiaticum isolates have been obtained from respiratory tract specimens (5, 6), lyphadenitis, bursitis, and wound specimens (7), and keratitis samples (8).…”