Mycobacterium marinum
| Characteristics | |
|---|---|
| Morphology | Mycobacterium marinum (M. marinum) is a non-tuberculous photochromogenic mycobacterium. Gram positive, non-motile, acid-fast, rod-shaped (slightly curved or straight rods) aerobic bacteria with high genomic DNA GC content. First isolated from saltwater fish in the 1920s and identified as a human pathogen in the 1950s. Sizes range from 1.0 to 10 μm, they are non-pigmented if grown in darkness but bright yellow if grown in light with either smooth to rough colonies (growth media dependent) |
| Growth Conditions | Growth on Löwenstein–Jensen (LJ) medium, oleic acidalbumin agar, or 7H9 medium at 30°C within 7 or more days |
| Health Hazards | |
|---|---|
| Host Range | Humans, domestic and wild animals |
| Modes of Transmission | M. marinum infection usually occurs following contact with an infected animal or handling of contaminated aquariums or water. It can also occur as an opportunistic infection, primarily in immune-deficient patients, such as those with human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS). |
| Signs and Symptoms | Overall there are 3 stages of M. marinum infections that have been characterized. They are the initial stage (type I), in which there are single or multiple skin papules or nodules; advanced stage (type II), in which there are granulomas (“fish tank granuloma” or “swimming pool granuloma”); and severe stage (type III), in which immunosuppressed patients experience tenosynovitis, arthritis, or osteomyelitis. |
| Infectious Dose | M. marinum infectious dose is estimated to be ~35 bacilli in most individuals |
| Incubation Period | Infection with M. marinum has an incubation period of about 2-3 weeks |
| Medical Precautions/Treatment | |
|---|---|
| Prophylaxis | The use of rifabutin for preventing and delaying the onset of bacteremia caused by M. avium complex infection in HIV infected patients has been recommended |
| Vaccines | None publically available |
| Treatment | Antibiotic treatment is available, a combination of several antibiotics over long periods of time is recommended for treatment. Surgery may be useful in removing debridement in soft tissue diseases |
| Surveillance | Monitor for symptoms. Diagnosis of infection can be done via culture of clinical specimens and identification using phenotypic characteristics (growth rate, colony pigmentation and biochemical tests) |
| GWU Requirements | Report all incidents to the Office of Risk Management as well as the Office of Research Safety (ORS) IMMEDIATELY FOLLOWING THE OCCURRENCE. |
| Containment | |
|---|---|
| BSL-2 | Risk Group 2 classification is applied to M. marinum. BSL-2 practices, containment equipment, and facilities are recommended for activities with clinical materials and cultures of M. marinum. Special caution is recommended in handling M. marinum to avoid skin exposure. |
| ABSL-2 | ABSL-2 practices, containment equipment, and facilities are recommended for animal studies. Selection of an appropriate tuberculocidal disinfectant is an important consideration for laboratories working with mycobacteria. |
| Spill Procedures | |
|---|---|
| Small Spills (<1 liter) | If the spill occurred inside a biological safety cabinet, close the sash and allow the cabinet to operate for 15 minutes before continuing with the spill cleanup.
M. marinum is not known to easily be aerosolized, but caution should be taken during a spill outside of a BSC. Leave the room immediately and allow the aerosols to dissipate for 15 minutes. Notify others working in the lab. Don appropriate PPE. Cover area of the spill with paper towels or any absorbent material and apply an EPA registered disinfectant effective against the bacteria (bleach, peroxyacetic acid, cavicide, ethanol), working from the perimeter towards the center. Allow 30 minutes of contact time before disposal and cleanup of spill materials. |
| Large Spills | Alert lab personnel in the laboratory to the spill and keep people out of the area to prevent spread of the contamination. Check if you have been contaminated or if any of your PPE has been breached. If so follow exposure procedures. Remove any contaminated clothing and place it the biohazard waste. Wash your hands and post a sign on the door. Notify your supervisor of the incident and call ORS (4-8258) for assistance. If the situation involves an imminently life-threatening injury or has catastrophic potential, call 911. |
| Exposure Procedures | |
|---|---|
| Mucus Membrane | Flush eyes, mouth or nose for 15 minutes at eyewash station. |
| Other Exposure | For an area not protected by skin, wash with soap and water for 15 minutes (open wounds, sores, etc.) |
| Reporting | Report ALL injuries to the PI immediately and reported to the Office of Risk Management at [email protected] IMMEDIATELY FOLLOWING THE OCCURRENCE. Exposures that involve a bloodborne-pathogen or recombinant DNA also need to be reported to the Office of Research Safety at [email protected]. If the injury requires immediate medical attention, call GWPD at 202-994-6111 or call 911. |
| Medical Monitoring | Seek immediate medical evaluation, treatment, and post exposure follow-up at the Employee Health Office at GWU Hospital (900 23rd St., NW, Suite G-1090, Phone: 202-715-4275). Students should go to the Students Health Office at Marvin Center. After hours treatment can be received at the GWU hospital emergency room. |
| Stability | |
|---|---|
| Disinfection | Mycobacteria are more resistant to disinfectants than vegetative bacteria. Atypical mycobacteria are generally susceptible to sodium hydroxide, chlorine dioxide, ethylene oxide, 0.35% peracetic acid, and orthophthalaldehyde. 70% ethanol can be used for surface disinfection |
| Inactivation | Mycobacteria are easily inactivated by heat (> 65 °C for at least 30 min) and by UV light but not by freezing or desiccation |
| Survival Outside Host | Mycobacteria are able to survive for weeks to months on inanimate objects if protected from sunlight. They are widely distributed in nature and have been found in natural water, tap water, soil, water used in showers and surgical solutions. |
| Personal Protective Equipment (PPE) | |
|---|---|
| Minimum PPE Requirements | At minimum, personnel are required to don gloves, closed toed shoes, lab coat, and appropriate face and eye protection prior to working with M. marinum. Additional PPE may be required depending on lab specific SOPs. |
| Additional Precautions | Additional protection may be worn over laboratory clothing when infectious materials are directly handled, such as solid-front gowns with tight fitting wrists, gloves, and respiratory protection. Wash hands with soap and water after removing gloves. |
| References | |
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References | |