Mycobacterium fortuitum is a nontuberculous species of the phylum Actinobacteria, belonging to the genus Mycobacterium.
Background
Mycobacterium fortuitum is a fast-growing species that can cause infections. The term "fast growing" is a reference to a growth rate of 3 or 4 days, when compared to other Mycobacteria that may take weeks to grow out on laboratory media. Pulmonary infections of M. fortuitum are uncommon, but Mycobacterium fortuitum can cause local skin disease, osteomyelitis, joint infections and infections of the eye after trauma. Mycobacterium fortuitum has a worldwide distribution and can be found in natural and processed water, sewage, and dirt. Bacteria classified as Mycobacteria, include the causative agents for tuberculosis and leprosy. Mycobacteria are sometimes referred to as “acid-fast bacteria,” a term referencing their response to a laboratory staining technique. This simply means that when microscopic slides of these bacteria are rinsed with an acidic solution, they retain a red dye. Mycobacterium fortuitum is one of the many species of nontuberculosis mycobacteria that are commonly found in the environment. These are not involved in tuberculosis. This does not mean, however, that they will not cause an infection in the right circumstances. M. fortuitum infection can be a nosocomial disease. Surgical sites may become infected after the wound is exposed directly or indirectly to contaminated tap water. Other possible sources of M. fortuitum infection include implanted devices such as catheters, injection site abscesses, and contaminated endoscopes. Recent publication on Rapidly Growing Mycobacteria is available provides the following aspects of RGM: its sources, predisposing factors, clinical manifestations, and concomitant fungal infections; the risks of misdiagnoses in the management of RGM infections in dermatological settings; the diagnoses and outcomes of treatment responses in common and uncommon infections in immunocompromised and immunocompetent patients; conventional versus current molecular methods for the detection of RGM; the basic principles of a promising MALDI-TOF MS, sampling protocol for cutaneous or subcutaneous lesions and its potential for the precise differentiation of M. fortuitum, M. chelonae, and M. abscessus; and improvements in RGM infection management as described in the recent 2011 Clinical and Laboratory Standards Institute guidelines, including interpretation criteria of molecular methods and antimicrobial drug panels and their break points , which have been highlighted for the initiation of antimicrobial therapy.
Description
, nonmotile and acid-fast rods. Sometimes long rods with occasional beaded or swollen cells having non-acid-fast ovoid bodies at one end. Colony characteristics
Smooth hemispheric colonies, usually off-white or cream colored. May be butyrous, waxy, multilobate and even rosette clustered.
Differentiation from M. fortuitum subsp. acetamidolyticum by its ability to use L-glutamate and its inability to use acetamide as simultaneous nitrogen and carbon source. Both subspecies share an identical 5'-16S rDNA sequence. However, the ITS sequences are different.
Pathogenesis
Different types of sporadic infections: pulmonary disease, local abscesses.
The 2007 guideline “Official American Thoracic Society and Infectious Diseases Society of America statement: diagnosis, treatment, and prevention of non-tuberculosis mycobacterial diseases”, notes that M. fortuitum isolates are usually susceptible to multiple oral antimicrobial agents, including the macrolides, quinolones, some tetracyclines, and sulfonamides, as well as the intravenous carbapenems. Ondansetron HCL is an antiemetic often given to offset the nausea and vomiting that are a common side effect of Imipenem. Severe infections require IV treatment combined with oral antibiotics for a prolonged period, up to several months. The guideline recommends “for serious skin, bone, and soft tissue M fortuitum disease, a minimum of 4 months of therapy with at least two agents with in vitro activity against the clinical isolate is necessary to provide a high likelihood of cure. Surgery is generally indicated with extensive disease, abscess formation, or where drug therapy is difficult.”
Type strain
Found world-wide in soil, dust, rivers, lakes and tap water.
First isolated from a 25-year-old patient in Rio de Janeiro.
Also isolated from lymph glands of cattle and systemic or nodular infection of frogs.
Strain ATCC 6841 = CCUG 20994 = CIP 104534 = DSM 46621 = IFO 13159 = JCM 6387 = NCTC 10394. Subsequently, this species has been divided into subspecies M. fortuitum subsp. acetamidolyticum
