Treatment of Biopsy and Culture Negative Mycobacterium Marinum: Diagnostic and Therapeutic Considerations
February 2014 | Volume 13 | Issue 2 | Case Reports | 204 | Copyright © February 2014
Patrick Tenbrick,a Michael Beer,b and Kenneth Beer MD PAa
aKenneth Beer MD PA Surgical, Cosmetic and General Dermatology, West Palm Beach, FL
bUniversity of Toledo Medical School, Toledo, OH
Mycobacterium marinum () infections are frequently linked to aquatic environments. Cutaneous infections with these organisms cause
superficial nodules, ulcerations, and pustules on the skin. Involvement of the deeper tissue may occur when diagnosis and treatment
are delayed, allowing the organisms to spread. The diagnostic criteria for infections rely on a detailed patient history, a typical clinical
presentation, positive cultures, characteristic organism smear, and if available CR-RFLP analysis and sequencing of 65 kD hsp gene.
However, when the pathology is not diagnostic for and the cultures and smears are negative, treatment may be delayed despite clinical
suspicion. The accuracy of bacterial cultures and smears for infections has been shown to be variable with ranges between 10% -
60%, leaving many infections unconfirmed.16,17,18
Despite the difficulty in diagnosis, early suspicion of is critical because of the dangers
imposed by delayed treatment. Prior reports have documented invasive surgical debridement and amputation due to delayed diagnosis
This case study demonstrates the need for clinical suspicion and accurate patient history for the correct treatment of.
The patient reported presented with classic signs and symptoms as well as a strong history of frequent contact with aquariums and
with fish obtained during frequent fishing trips but did not have positive stains or a positive culture for The approach to patients such
as this one is critical to avoidance of complications and prolonged infections, which can have dire consequences.
J Drugs Dermatol.
Atypical Mycobacterium, also known as nontuberculous
mycobacterium, are small, rod-shaped bacilli that cause
infections via environmental interactions, with the most
common type being Mycobacterium marinum (M marinum).1,2
M. marinum is a saltwater and freshwater environmental bacterium
that is a photochromogen classified in Runyon group 1.3,4
M. marinum infections are seen after abrasions or following the
introduction of open wounds into wet environments containing
the bacteria. These environments are most commonly aquariums,
salt-water environments, or direct marine animal contact.1,5
The typical clinical presentation of M. marinum includes superficial
nodules, ulcerations, and pustules on the skin. Lesions are
usually localized to the extremities, originating around the site
of injury and spreading in a linear, sporotrichoid pattern following
superficial lymph flow.6,7,8 M. marinum can also cause more
severe complications such as tenosynovitis, bursitis, septic arthritis,
and osteomyelitis if left untreated.9,10,6,8 The longer the
infection is undiagnosed or untreated, the higher the risk of significant
morbidities (8). The diagnosis of M. marinum is based
on a detailed patient history, physical examination and histological
patterns along with positive staining for organisms. Cultures,
and CR-RFLP analysis and sequencing of 65 kD heat shock protein
are also important for the diagnosis of infection.11,6,12,13 While
culture and histological identification are considered critical
in the diagnosis of M. marinum, not all cases will be positive.
Delayed or inaccurate diagnoses can lead to inappropriate and
costly treatments that can potentially harm and extend the M. marinum infection14 as well as protracted infections from lack of treatment. Infections in humans are not common, an estimated
0.27 cases per 100,000 adult patients.10 However, they are important
to recognize and to treat in order to prevent long-term
infections with the morbidity associated with this. The case presented
here is representative of patients that do not have classic
histology, staining or positive cultures. The question of how to
manage such a patient in the absence of PCR availability is one
that is relevant for clinicians presented with this situation.
A 68-year-old man presented to the dermatology clinic complaining
of nodules on his hands. He stated that the nodules had
first appeared on the dorsum of his dominant (right) hand approximately
two months prior to his visit. Since that time, they
had spread proximally and he noted swelling of his olecranon
bursa. He stated that the lesions were not painful and he denied
fever or chills. His social history revealed that he had significant
exposure to marine life both as an avid fisherman as well as a
salt-water fish hobbyist with tanks that were thousands of gallons.
Upon further questioning, he recalled a particular incident
when he was stabbed by the dorsal fin of a fish and he believed
that the nodules appeared a few weeks after this.
Examination revealed scattered 1- 2cm rock hard nodules on
the dorsum of his hand as well as on the dorsal arm (Figure 1).
There was diffuse edema and swelling surrounding his elbow.
No lymphadenopathy was appreciated in either his axilla or