Mycobacterium haemophilum infection with prominent facial manifestation mimicking leprosy

Mycobacterium haemophilum infection with cutaneous involvement: two case reports and an updated literature review: Mycobacterium haemophilum skin infection

Mycobacterium haemophilum (MH) is a slow-growing, non-tuberculous Mycobacterium that most commonly causes infections in immunocompromised patients. The skin is the most prevalent site of infection and can be an isolated presentation or part of a disseminated disease. Herein, we reported a case of isolated MH infection of the hand and a case of disseminated MH infection with multiple skin lesions. In addition, other MH cases with cutaneous involvement over the last 10 years, from 2011-2022, were reviewed and analyzed. Among the 79 included cases, the common skin findings in MH infections included nodules, ulcers, abscesses, swelling, and pustules. Middle-aged patients with iatrogenic immunosuppression from glucocorticoids, mycophenolate mofetil, cyclosporine, and cyclophosphamide are the most susceptible to MH infection, with a higher risk of dissemination to internal organs. Disseminated MH infections commonly present as tenosynovitis, arthritis/arthralgia, or osteomyelitis. There is a lack of strong evidence for treatment; however, triple therapy of quinolone, macrolides, and rifampicin is most often used in clinical practice. The overall prognosis is good. The presence of iatrogenic immunocompromised diseases, lesions involving the proximal limbs, and dissemination of MH infections are associated with worse clinical outcomes.

Hautbeteiligung bei Infektionen mit Mycobacterium haemophilum: Zwei Fallberichte und eine aktualisierte Literaturübersicht: Mycobacterium haemophilum infection with cutaneous involvement: Two case reports and an updated literature review

Mycobacterium haemophilum (MH) ist ein langsam wachsendes, nicht‐tuberkulöses Mykobakterium. Infektionen treten am häufigsten bei Patienten mit beeinträchtigtem Immunsystem auf; sie manifestieren sich meist an der Haut und kommen isoliert oder bei disseminierten Infektionen vor. Wir berichten hier über einen Fall mit isolierter MH‐Infektion an der Hand sowie über einen weiteren Fall von disseminierter MH‐Infektion mit multiplen Hautläsionen. Zusätzlich haben wir weitere Fallberichte über MH‐Infektionen mit kutaner Beteiligung aus den letzten zehn Jahren (2011–2022) ausgewertet. Die am häufigsten beobachteten Hautmanifestationen der insgesamt 79 Fälle waren Knötchen, Ulzera, Abszesse, Schwellungen und Pusteln. Patienten mittleren Alters mit iatrogener Immunsuppression durch Glucocorticoide, Mycophenolat‐Mofetil, Ciclosporin und Cyclophosphamid scheinen besonders anfällig für MH‐Infektionen zu sein und haben auch ein höheres Risiko für eine Dissemination in die inneren Organe. Disseminierte MH‐Infektionen manifestieren sich gewöhnlich als Tenosynovitis, Arthritis/Arthralgie oder Osteomyelitis. Derzeit gibt es keine starke Evidenz für bestimmte Therapeutika; in der Praxis wird am häufigsten eine Dreifachkombination aus Chinolon, Makroliden und Rifampicin eingesetzt. Die Prognose ist allgemein gut. Iatrogene Immunsuppression, Läsionen im proximalen Bereich der Extremitäten sowie disseminierte Manifestation sind mit schlechteren klinischen Verläufen assoziiert.

Disseminated cutaneous Mycobacterium haemophilum infection in a patient on infliximab for rheumatoid arthritis

Mycobacterium haemophilum is a rarely encountered pathogen that is difficult to identify given its unique growth requirements. It is most often seen in adult patients who are immunosuppressed due to advanced HIV or haematological malignancy. Our case highlights a typical presentation of an atypical pathogen in a patient with rheumatoid arthritis receiving anti-tumour necrosis factor therapy. This case represents an important patient population in whom this previously rare infection is increasingly common.

Other Slow-Growing Nontuberculous Mycobacteria

The list of clinically important slow-growing nontuberculous mycobacteria (NTM) continues to expand as new species are identified and older ones are found to be pathogenic. Based on pigment production, the strains may be classified as photochromogenic, scotochromogenic, or unpigmented. Some of these organisms are not newly discovered but have heretofore been considered virtually nonpathogenic. Previously, many were regarded as contaminants when isolated from clinical specimens. Ubiquitous in nature, many NTM have been isolated from groundwater or tap water, soil, house dust, domestic and wild animals, and birds. Most infections result from inhalation or direct inoculation from environmental sources. They are not spread from person to person. The infections may be localized or disseminated. In most cases, the optimal regimen or duration of therapy has not been firmly established. The results of in vitro susceptibility testing may be used to select a therapeutic regimen. Many experts recommend clarithromycin with companion drugs such as rifampin and ethambutol for most, but not all, slowly growing species. Aminoglycosides, clofazimine, fluoroquinolones, linezolid, pyrazinamide, or trimethoprim-sulfamethoxazole also may be effective against some strains. Immunocompetent patients with clinically significant infections with NTM usually should receive 18 to 24 months of therapy. Infected immunocompromised patients, particularly those with disseminated infection, probably should receive therapy as long as their immune systems remain impaired. Some of the species discussed include Mycobacterium alsiense, M. celatum, M. gordonae, M. haemophilum, M. kyorinense, M. malmoense, M. simiae complex, M. szulgai, M. terrae complex, M. ulcerans, and M. xenopi.

Leprosy with ulnar nerve abscess: ultrasound findings in a child

We report the ultrasound findings of a typical case of nerve abscess due to leprosy in an 11-year-old boy. The patient had previously undergone pediatric multibacillary leprosy multidrug therapy (MDT) in accordance with World Health Organization guidelines. He presented to our service with bilateral ulnar neuritis with no response to prednisone (1 mg/kg). Right ulnar nerve ultrasound revealed nerve hypoechogenicity, fascicular pattern disorganization, marked fusiform thickening, and a round anechoic area suggestive of intraneural abscess. Intense intraneural power Doppler signal was detected, indicating active neuritis. Intravenous methylprednisolone had a poor response and the patient was submitted to ulnar nerve decompression, which confirmed nerve abscess with purulent discharge during surgery. As the patient weighed more than 40 kg, treatment with a pediatric dose was considered insufficient and adult-dose MDT was prescribed, with improvement of nerve pain and function. Although leprosy is rare in developed countries, it still exists in the USA and it is endemic in many developing countries. Leprosy neuropathy is responsible for the most serious complications of the disease, which can lead to irreversible impairments and deformities. Nerve abscess is an uncommon complication of leprosy and ultrasound can efficiently demonstrate this condition, allowing for prompt treatment. There is scant literature about the imaging findings of nerve abscess in leprosy patients. Radiologists should suspect leprosy in patients with no other known causes of neuropathy when detecting asymmetric nerve enlargement and nerve abscess on ultrasound.

Disseminated Mycobacterium haemophilum infection in a renal transplant recipient

Opportunistic infections are a major concern in renal and transplant medicine. We present the case of a renal transplant recipient with a generalised Mycobacterium haemophilum infection after an increase in immunosuppressive therapy and treatment with a tumour necrosis factor-α (TNF-α) inhibitor. Infection involved skin and soft tissue, joints and bones, as well as the renal transplant with an interstitial nephritis. Rapid diagnosis using PCR and DNA sequencing allowed early appropriate treatment. Triple antibiotic therapy and reduction in immunosuppression resulted in a slow but sustained recovery. Immunosuppression causes severe opportunistic infections. TNF-α inhibitors are very effective and well tolerated but have an increased susceptibility to infections with mycobacteria. Mycobacterial infections represent a significant clinical risk to transplant recipients because of their aggressive clinical course and the need for complex toxic antibiotic treatments. In these patients, M. haemophilum is a cause of skin infections.

Mycobacterium haemophilum infection in a juvenile leatherback sea turtle (Dermochelys coriacea)

Mycobacteriosis is infrequently reported in free-ranging sea turtles. Nontuberculous Mycobacterium haemophilum was identified as the causative agent of disseminated mycobacteriosis in a juvenile leatherback turtle (Dermochelys coriacea) that was found stranded on the Atlantic coast of Florida. Disseminated granulomatous inflammation was identified histologically, most notably affecting the nervous system. Identification of mycobacterial infection was based on cytologic, molecular, histologic, and microbiologic methods. Among stranded sea turtles received for diagnostic evaluation from the Atlantic and Gulf of Mexico coasts of the United States between 2004 and 2015, the diagnosis of mycobacteriosis was overrepresented in stranded oceanic-phase juveniles compared with larger size classes, which suggests potential differences in susceptibility or exposure among different life phases in this region. We describe M. haemophilum in a sea turtle, which contributes to the knowledge of diseases of small juvenile sea turtles, an especially cryptic life phase of the leatherback turtle.

The Complete Genome Sequence of the Emerging Pathogen Mycobacterium haemophilum Explains Its Unique Culture Requirements

Mycobacterium haemophilum is an emerging pathogen associated with a variety of clinical syndromes, most commonly skin infections in immunocompromised individuals. M. haemophilum exhibits a unique requirement for iron supplementation to support its growth in culture, but the basis for this property and how it may shape pathogenesis is unclear. Using a combination of Illumina, PacBio, and Sanger sequencing, the complete genome sequence of M. haemophilum was determined. Guided by this sequence, experiments were performed to define the basis for the unique growth requirements of M. haemophilum. We found that M. haemophilum, unlike many other mycobacteria, is unable to synthesize iron-binding siderophores known as mycobactins or to utilize ferri-mycobactins to support growth. These differences correlate with the absence of genes associated with mycobactin synthesis, secretion, and uptake. In agreement with the ability of heme to promote growth, we identified genes encoding heme uptake machinery. Consistent with its propensity to infect the skin, we show at the whole-genome level the genetic closeness of M. haemophilum with Mycobacterium leprae, an organism which cannot be cultivated in vitro, and we identify genes uniquely shared by these organisms. Finally, we identify means to express foreign genes in M. haemophilum. These data explain the unique culture requirements for this important pathogen, provide a foundation upon which the genome sequence can be exploited to improve diagnostics and therapeutics, and suggest use of M. haemophilum as a tool to elucidate functions of genes shared with M. leprae.

IMPORTANCE

Mycobacterium haemophilum is an emerging pathogen with an unknown natural reservoir that exhibits unique requirements for iron supplementation to grow in vitro. Understanding the basis for this iron requirement is important because it is fundamental to isolation of the organism from clinical samples and environmental sources. Defining the molecular basis for M. haemophilium's growth requirements will also shed new light on mycobacterial strategies to acquire iron and can be exploited to define how differences in such strategies influence pathogenesis. Here, through a combination of sequencing and experimental approaches, we explain the basis for the iron requirement. We further demonstrate the genetic closeness of M. haemophilum and Mycobacterium leprae, the causative agent of leprosy which cannot be cultured in vitro, and we demonstrate methods to genetically manipulate M. haemophilum. These findings pave the way for the use of M. haemophilum as a model to elucidate functions of genes shared with M. leprae.