Mycobacterium africanumCases, California

Abstract

Five Mycobacterium tuberculosis complex isolates in California were identified as M. africanum by spoligotyping, single nucleotide polymorphisms, a deletion mutation, and phenotypic traits, confirming it as a cause of tuberculosis in the United States. Three of the five patients from whom M. africanum was isolated had lived in Africa.M ycobacterium africanum is a member of the M. tuberculosis complex, which has been isolated from humans in equatorial Africa. The disease produced by M. africanum is similar to that caused by M. tuberculosis or M. bovis, and like M. tuberculosis, this organism is likely spread by aerosol transmission (1). Human tuberculosis caused by M. africanum has been reported in Europe (2,3). However, we are unaware of previous reports of disease caused by M. africanum in the United States. The StudyM. africanum may be identified by spoligotyping (4), by specific deletion mutations (5), DNA fingerprinting by IS6110 restriction fragment length polymorphisms (RFLP) (4), or a combination of these methods. Isolates were initially identified as M. tuberculosis complex by using the AccuProbe system (Gen-Probe; San Diego, CA). The isolates then underwent IS6110-based RFLP fingerprinting. The RFLP analyses were performed according to the method of van Embden et al. (6). In addition to providing genotyping results, RFLP fingerprinting confirmed the identification obtained with Accuprobe.All strain typing was performed in-house at the Microbial Diseases Laboratory, California Department of Health Services. This laboratory has compiled a database (Genomic Solutions BioImage) of approximately 7,000 DNA fingerprints, typed by IS6110 RFLP (6,7) from throughout California; most are from the San Francisco Bay area. Three isolates (from patients A, B, and C) were initially suspected of being M. africanum because of an epidemiologic association with Africa. These isolates were fingerprinted by IS6110 RFLP and by spoligotyping (8).All three were found to have the "signature" spoligotype described by Viana-Niero et al. as being characteristic of M. africanum (4), namely, they were missing spacers 8, 9, and 39 but had spacers 40-43. Using BioImage software, we searched the laboratory's database for IS6110 fingerprints that matched those of the three cases with an African connection. This search yielded an additional two matches, cases D and E. Isolates from cases D and E were then genotyped by using spoligotyping and found to have the M. africanum signature spoligotype.The five M. africanum isolates were further characterized by performing standard biochemical identification tests and testing for susceptibility to pyrazinamide (PZA). Niacin production and nitrate reduction were detected as described by Kent and Kubica (9). Susceptibility to PZA was determined by using the BACTEC radiometric assay performed according to the method of Salfinger et al. (10). The M. africanum isolates were then examined to determine whether they had the RD9 deletion and specific oxyR and katG sequence mutations.Brosch et al. had repor...

Multiplex Real-Time PCR Assay for Rapid Identification ofMycobacterium tuberculosisComplex Members to the Species Level

“…To further characterize the assay, we analyzed an additional 15 clinical isolates representing 15 distinct spoligotypes commonly associated with strains of M. bovis, as well as 5 clinical isolates of M. africanum (14). Whereas all 5 of the M. africanum isolates had the expected RD pattern, surprisingly, we found that our assay identified 13% (2/15) of these putative M. bovis isolates as MTC members other than classical M. bovis.…”

The Genome of Mycobacterium Africanum West African 2 Reveals a Lineage-Specific Locus and Genome Erosion Common to the M. tuberculosis Complex

“…Today, M. africanum is rarely isolated outside of West Africa, typically in first degree immigrants [62]. In a study in Ghana, host polymorphisms were identified with differential protection against M. tuberculosis versus M. africanum in both directions [63], [64], although the degree of selective advantage conferred by these polymorphisms is unclear.…”

Use of Spoligotyping and Large Sequence Polymorphisms To Study the Population Structure of the Mycobacterium tuberculosis Complex in a Cohort Study of Consecutive Smear-Positive Tuberculosis Cases in The Gambia

“…DNA from both M. africanum and M. tuberculosis sensu stricto was recovered from Egyptian mummies (28), yet today M. africanum isolates are rarely encountered outside of West Africa, except among first-generation immigrants (8). This lack of spread of M. africanum, despite large migrations, such as through the slave trade to the New World, (6).…”