Mycobacterium marinum Susceptibility
Determine the susceptibility of Mycobacterium marinum isolates to a profile of antimycobacterial agents. Routine susceptibility testing of M marinum isolates is generally not recommended.1,2 Agents that have successfully been used as single agents for therapy include rifampin, doxycycline, minocycline, sulfamethoxazole-trimethoprim, and clarithromycin. Since isolates of M marinum have a very narrow range of MICs for each of these agents, and because disease due to M marinum is generally localized and the number of organisms is low (95% of tissue biopsies are AFB smear negative), single drug therapy is widely used and acquired mutational resistance is rare. Susceptibility testing should, however, be considered for patients that remain culture positive after more than three months of therapy.3
Few comparative studies have been performed relating clinical outcome with in vitro susceptibility testing. Ciprofloxacin is not recommended for therapy because some strains are resistant and with monotherapy, the risk of mutational resistance increases.
Mycobacterium marinum isolated from a primary clinical specimen, on a submitted AFB conventional solid medium, or an AFB broth medium
Pure culture isolate on an AFB conventional solid medium or a minimum of 1 mL of AFB broth medium
Conventional or broth medium, tightly sealed, in etiologic agent packaging
Maintain specimen at room temperature.
EDTA or citrate plasma specimen