Cutaneous Mycobacterial Infections.

Humans encounter mycobacterial species due to their ubiquity in different environmental niches. In many individuals, pathogenic mycobacterial species may breach our first-line barrier defenses of the innate immune system and modulate the activation of phagocytes to cause disease of the respiratory tract or the skin and soft tissues, sometimes resulting in disseminated infection. Cutaneous mycobacterial infections may cause a wide range of clinical manifestations, which are divided into four main disease categories: (i) cutaneous manifestations of Mycobacterium tuberculosis infection, (ii) Buruli ulcer caused by Mycobacterium ulcerans and other related slowly growing mycobacteria, (iii) leprosy caused by Mycobacterium leprae and Mycobacterium lepromatosis, and (iv) cutaneous infections caused by rapidly growing mycobacteria. Clinically, cutaneous mycobacterial infections present with widely different clinical presentations, including cellulitis, nonhealing ulcers, subacute or chronic nodular lesions, abscesses, superficial lymphadenitis, verrucous lesions, and other types of findings. Mycobacterial infections of the skin and subcutaneous tissue are associated with important stigma, deformity, and disability. Geography-based environmental exposures influence the epidemiology of cutaneous mycobacterial infections. Cutaneous tuberculosis exhibits different clinical phenotypes acquired through different routes, including via extrinsic inoculation of the tuberculous bacilli and dissemination to the skin from other sites, or represents hypersensitivity reactions to M. tuberculosis infection. In many settings, leprosy remains an important cause of neurological impairment, deformity, limb loss, and stigma. Mycobacterium lepromatosis, a mycobacterial species related to M. leprae, is linked to diffuse lepromatous leprosy of Lucio and Latapí. Mycobacterium ulcerans produces a mycolactone toxin that leads to subcutaneous tissue destruction and immunosuppression, resulting in deep ulcerations that often produce substantial disfigurement and disability. Mycobacterium marinum, a close relative of M. ulcerans, is an important cause of cutaneous sporotrichoid nodular lymphangitic lesions. Among patients with advanced immunosuppression, Mycobacterium kansasii, the Mycobacterium avium-intracellulare complex, and Mycobacterium haemophilum may cause cutaneous or disseminated disease. Rapidly growing mycobacteria, including the Mycobacterium abscessus group, Mycobacterium chelonei, and Mycobacterium fortuitum, are increasingly recognized pathogens in cutaneous infections associated particularly with plastic surgery and cosmetic procedures. Skin biopsies of cutaneous lesions to identify acid-fast staining bacilli and cultures represent the cornerstone of diagnosis. Additionally, histopathological evaluation of skin biopsy specimens may be useful in identifying leprosy, Buruli ulcer, and cutaneous tuberculosis. Molecular assays are useful in some cases. The treatment for cutaneous mycobacterial infections depends on the specific pathogen and therefore requires a careful consideration of antimicrobial choices based on official treatment guidelines.

Extended spectrum of antibiotic susceptibility for tuberculosis, Djibouti.

In the Horn of Africa, there is a high prevalence of tuberculosis that is reported to be partly driven by multidrug-resistant (MDR) Mycobacterium tuberculosis strictu sensu strains. We conducted a prospective study to investigate M. tuberculosis complex species causing tuberculosis in Djibouti, and their in vitro susceptibility to standard anti-tuberculous antibiotics in addition to clofazimine, minocycline, chloramphenicol and sulfadiazine. Among the 118 mycobacteria isolates from 118 successive patients with suspected pulmonary tuberculosis, 111 strains of M. tuberculosis, five Mycobacterium canettii, one 'Mycobacterium simulans' and one Mycobacterium kansasii were identified. Drug-susceptibility tests performed on the first 78 isolates yielded nine MDR M. tuberculosis isolates. All isolates were fully susceptible to clofazimine, minocycline and chloramphenicol, and 75 of 78 isolates were susceptible to sulfadiazine. In the Horn of Africa, patients with confirmed pulmonary tuberculosis caused by an in vitro susceptible strain may benefit from anti-leprosy drugs, sulfamides and phenicol antibiotics.

Micobacteriosis pulmonar por Mycobacterium kansasii / Micobacteriosis pulmonar por Mycobacterium kansasii

Micobacterias no tuberculosas (MNT) es una designación utilizada para referirse a un gran número de especies de micobacterias ambientales potencialmente patógenas y no patógenas, distintas de la Mycobacterium tuberculosis y Mycobacterium leprae. Mycobacterium kansasii (M. Kansasii) es una MNT oportunista causante de infecciones pulmonares, cutáneas, entre otras, cuya tasa de incidencia ha ido incrementando en los últimos años a nivel mundial. A través de presentar el siguiente caso se pretende aportar al conocimiento con respecto al abordaje de pacientes con infección por MNT a nivel pulmonar, dirigido a médicos que trabajan en atención primaria de salud (APS). Se trata del caso de una paciente de 46 años de edad que acude al Hospital Provincial General Docente de Riobamba (HPGDR) con infección por MNT a nivel pulmonar. En el examen microscópico se detectaron Bacilos­Ácido­Alcohol­Resistentes (BAAR) mientras en el cultivo de esputo más antibiograma se aisló M. kansasii resistente a los antibióticos utilizados para la terapia convencional de tuberculosis. Se trata de un caso raro en la práctica clínica. Es crucial saber cómo manejar una infección con M. kansasii debido a su implicación para la salud del paciente y el sistema de salud nacional. El médico de APS debe reconocer su papel fundamental y la importancia que tiene un diagnóstico oportuno y tratamiento adecuado.

Non­tuberculous mycobacteria (NTM) is a designation for a large number of mycobacterial species potentially pathogenous and non­pathogenous, different than Mycobacterium tuberculosis and Mycobacterium leprae. Mycobacterium kansasii (M. kansasii) is an opportunistic NTM that causes among other things, pulmonary and cutaneous infections, whose incidence is increasing worldwide. Trough the following case report we seek to provide a guide to physicians working on primary health care (PHC) on the management of patients with pulmonary infection caused by NTM. We report the case of a 46­year­old female patient who came to the Hospital Provincial General Docente de Riobamba (HPGDR) with a pulmonary infection caused by NTM. In the microscopic examination it was identified Acid­Fast Bacilli (AFB), meanwhile the microbiological culture and antibiogram it was isolated M. kansasii resistant to common antibiotics used for conventional tuberculosis therapy. It is a rare case in the clinical practice. It is crucial to know how to manage an infection with M. Kansasii due to its implication on the health of affected subjects and the national health system. A physician working on PHC has to know his/her fundamental role and the importance of an early diagnosis and adequate treatment.

Consensus numbering system for the rifampicin resistance-associated rpoB gene mutations in pathogenic mycobacteria.

The rpoB gene codes for the RNA polymerase ß subunit, which is the target of rifampicin, an essential drug in the treatment of tuberculosis and other mycobacterial infections. This gene is present in all bacteria, but its length and nucleotide sequence vary between bacterial species, including mycobacteria. Mutations in the rpoB gene alter the structure of this protein and cause drug resistance. To describe the resistance-associated mutations, the scientific and medical communities have been using, since 1993, a numbering system based on the Escherichia coli sequence annotation. Using E. coli reference for describing mutations in mycobacteria leads to misunderstandings, particularly with the increasing use of whole genome sequencing, which brought an alternative numbering system based on the Mycobacterium tuberculosis rpoB sequence. We propose using a consensus numbering system for the reporting of resistance mutations based on the reference genomes from the species interrogated (such as strain H37Rv for M. tuberculosis). This manuscript provides the necessary figures and tables allowing researchers, microbiologists and clinicians to easily convert other annotation systems into one common language.