Vella A. Silcox

Mycobacterium chelonae Wound Infections after Plastic Surgery Employing Contaminated Gentian Violet Skin-Marking Solution

From April 1 to October 31, 1985, postoperative surgical-wound infections due to rapidly growing mycobacteria developed in eight patients undergoing cosmetic plastic surgery performed by one surgeon. All infections followed either face-lift or augmentation-mammoplasty procedures performed in the surgeons office; no infections occurred after surgical procedures performed at the hospital or after other surgical procedures performed at the office. An epidemiologic investigation implicated a gentian violet skin-marking solution as the source of the infections (P less than 0.001). Among patients exposed to the gentian violet, infection was significantly more likely to develop in those undergoing a face lift or augmentation mammoplasty than in those undergoing blepharoplasty (P less than 0.001). Additional risk factors for infection included the postoperative use of antibiotics and glucocorticoids. Mycobacterium chelonae, subspecies abscessus, was isolated from the gentian violet stock used by the surgeon and from five of the eight patients. Additional studies showed that the same organism was present in the gentian violet stock at the pharmacy that supplied the agent to the surgeon. After a sterile skin-marking agent was substituted for the contaminated agent, no further cases occurred.

Antimicrobial susceptibility of five subgroups of Mycobacterium fortuitum and Mycobacterium chelonae.

Broth microdilution MICs were determined for 258 clinical isolates of Mycobacterium fortuitum (3 biovariants) and M. chelonae (2 subspecies) with amikacin, tobramycin, cefoxitin, doxycycline, erythromycin, and sulfamethoxazole-trimethoprim and with several new beta-lactams and aminoglycosides and ciprofloxacin. Variations in susceptibility by and within species subgroups confirm the need for susceptibility testing against clinically important strains.

Rapidly growing mycobacteria: testing of susceptibility to 34 antimicrobial agents by broth microdilution.

A total of 18 strains of Mycobacterium fortuitum, 15 strains of M. chelonei, and 31 strains of M. chelonei-like organisms were tested by both broth microdilution and agar dilution to determine their susceptibility to 34 antimicrobial agents. All strains grew well enough in cation-supplemented Mueller-Hinton broth for endpoints to be read after 72 h of incubation. Some strains of M. chelonei did not grow on Mueller-Hinton agar. A few discrepancies were noted between the broth and agar procedures. For M. fortuitum, doxycycline, minocycline, amikacin, sulfamethoxazole, and sulfamethoxazole-trimethoprim were the most active agents. For M. chelonei, amikacin, sisomicin, tobramycin, and erythromycin were the most active agents. The M. chelonei-like organisms were most susceptible to ampicillin, doxycycline, minocycline, amikacin, erythromycin, sulfamethoxazole, and sulfamethoxazole-trimethoprim. Broth microdilution appears to be a reliable method for susceptibility testing of rapidly growing mycobacteria, although clinical studies are needed to determine how well in vitro results correlate with therapeutic in vivo outcome.

Sternal wound infections and endocarditis due to organisms of the Mycobacterium fortuitum complex

Excerpt Sternal wound infections after surgery occur in 0.5% to 6% of all patients requiring sternotomy incisions (1-4). Most infections have been due to staphylococci and aerobic gram-negative org...

A nosocomial pseudo-outbreak of Mycobacterium xenopi due to a contaminated potable water supply: lessons in prevention.

OBJECTIVES To determine risk factors for Mycobacterium xenopi isolation in patients following a pseudo-outbreak of infection with the organism. DESIGN Retrospective cohort analysis of mycobacteriology laboratory specimen records and frequency-matched case-control study of hospital patients. SETTING General community hospital. PATIENTS For the case-control study, 13 case patients and 39 randomly selected controls with mycobacterial cultures negative for M xenopi, frequency matched by specimen source, whose specimens were submitted from June 1990 through June 1991. RESULTS Between June 1990 and June 1991, M xenopi was isolated from 13 clinical specimens processed at a midwestern hospital, including sputum (n = 6), bronchial washings (2), urine (4), and stool (1). None of the patients with M xenopi-positive specimens had apparent mycobacterial disease, although five received antituberculosis drug therapy for a range of one to six months. Specimens collected in a nonsterile manner were more likely to grow the organism than those collected aseptically (3.1% versus 0, relative risk = infinity, P = 0.003). M xenopi isolation was attributed to exposure of clinical specimens to tap water, including rinsing of bronchoscopes with tap water after disinfection, irrigation with tap water during colonoscopy, gargling with tap water before sputum collection, and collecting urine in recently rinsed bedpans. M xenopi was isolated from tap water in 20 of 24 patient rooms tested, the endoscopy suite, and the central hot water mixing tank, but not from water in the microbiology laboratory. The pseudo-outbreak occurred following a decrease in the hot water temperature from 130 degrees F to 120 degrees F in 1989. CONCLUSIONS Maintenance of a higher water temperature and improved specimen collection protocols and instrument disinfection procedures probably would have prevented this pseudo-outbreak.

Clinical and Laboratory Features of Mycobacterium porcinum

ABSTRACT Recent molecular studies have shown Mycobacterium porcinum, recovered from cases of lymphadenitis in swine, to have complete 16S rDNA sequence identity and >70% DNA-DNA homology with human isolates within the M. fortuitum third biovariant complex. We identified 67 clinical and two environmental isolates of the M. fortuitum third biovariant sorbitol-negative group, of which 48 (70%) had the same PCR restriction enzyme analysis (PRA) profile as the hsp65 gene of M. porcinum (ATCC 33776T) and were studied in more detail. Most U.S. patient isolates were from Texas (44%), Florida (19%), or other southern coastal states (15%). Clinical infections included wound infections (62%), central catheter infections and/or bacteremia (16%), and possible pneumonitis (18%). Sequencing of the 16S rRNA gene (1,463 bp) showed 100% identity with M. porcinum ATCC 33776T. Sequencing of 441 bp of the hsp65 gene showed four sequevars that differed by 2 to 3 bp from the porcine strains. Clinical isolates were positive for arylsulfatase activity at 3 days, nitrate, iron uptake, d-mannitol, i-myo-inositol, and catalase at 68°C. They were negative for l-rhamnose and d-glucitol (sorbitol). Clinical isolates were susceptible to ciprofloxacin, sulfamethoxazole, and linezolid and susceptible or intermediate to cefoxitin, clarithromycin, imipenem, and amikacin. M. porcinum ATCC 33776T gave similar results except for being nitrate negative. These studies showed almost complete phenotypic and molecular identity between clinical isolates of the M. fortuitum third biovariant d-sorbitol-negative group and porcine strains of M. porcinum and confirmed that they belong to the same species. Identification of M. porcinum presently requires hsp65 gene PRA or 16S rRNA or hsp65 gene sequencing.

DIFFERENTIAL IDENTIFICATION OF MYCOBACTERIA VI. MYCOBACTERIUM TRIVIALE KUBICA SP. NOV.

ABSTRACT A new species of nonphot ochromogen mycobacteria is described. Most of the strains examined have been isolated from man; however, because of their lack of relationship to human disease, the name Mycobacterium triviale Kubica is proposed. The physical and biochemical characteristics, serologic activity, and thin layer chromatographic pattern of this new species serve to distinguish it from other nonphotochromo-genic mycobacteria in Runyons Group III.

Susceptibility of Mycobacteria to Rifampin

The Mycobacterium species M. tuberculosis, M. avium-intracellulare, M. kansasii, M. marinum, M. scrofulaceum, M. fortuitum, M. terrae, and M. gordonae were analyzed for their susceptibility to rifampin. M. tuberculosis, M. kansasii, and M. marinum were susceptible to the antibiotic, and resistant populations developed as a result of the interplay of mutation and selection. The mutation rates (susceptibility → resistance) were calculated to be 4.9 × 10−10 and 1.7 × 10−9 mutations per bacterium per generation in, respectively, M. kansasii and M. marinum. M. fortuitum was found to be naturally resistant to the antibiotic, whereas the nature of resistance in the other species was unclear and is discussed.

Bacteremia Caused by a Previously Unidentified Species of Rapidly Growing Mycobacterium Successfully Treated with Vancomycin

Bacteremia caused by rapidly growing mycobacteria are usually due to Mycobacterium fortuitum or M. chelonei. Other rapidly growing mycobacteria generally are considered to be nonpathogenic. We report the case of a patient with bacteremia due to an unidentified, rapidly growing, scotochromogenic mycobacteria that was detected by a radiometric blood culture system. Results of in-vitro susceptibility testing indicated that the organism was susceptible to vancomycin and other antimicrobial agents, and the patient was successfully treated with vancomycin. We believe that this is the first report of successful use of vancomycin therapy for a mycobacterial infection.

The Use of DNA Probes for Rapidly Identifying Cultures of Mycobacterium

There has been an explosion of new technology for the rapid, specific identification of many microorganisms pathogenic for humans. These new methods have been especially welcomed in the mycobacteriology laboratory, plagued by long bacterial generation times that translated into specific identification periods measured in months. The race to develop these methods and to make them easy to perform and the secrecy surrounding new patent applications for some of the unique procedures employed have spawned such terms as “dipstick- or black box-technology” to describe these welcome additions to diagnostic microbiology.