Delayed recognition of a pseudo-outbreak of Mycobacterium terrae

Methodological and Clinical Aspects of the Molecular Epidemiology of Mycobacterium tuberculosis and Other Mycobacteria

Molecular typing has revolutionized epidemiological studies of infectious diseases, including those of a mycobacterial etiology. With the advent of fingerprinting techniques, many traditional concepts regarding transmission, infectivity, or pathogenicity of mycobacterial bacilli have been revisited, and their conventional interpretations have been challenged. Since the mid-1990s, when the first typing methods were introduced, a plethora of other modalities have been proposed. So-called molecular epidemiology has become an essential subdiscipline of modern mycobacteriology. It serves as a resource for understanding the key issues in the epidemiology of tuberculosis and other mycobacterial diseases. Among these issues are disclosing sources of infection, quantifying recent transmission, identifying transmission links, discerning reinfection from relapse, tracking the geographic distribution and clonal expansion of specific strains, and exploring the genetic mechanisms underlying specific phenotypic traits, including virulence, organ tropism, transmissibility, or drug resistance. Since genotyping continues to unravel the biology of mycobacteria, it offers enormous promise in the fight against and prevention of the diseases caused by these pathogens. In this review, molecular typing methods for Mycobacterium tuberculosis and nontuberculous mycobacteria elaborated over the last 2 decades are summarized. The relevance of these methods to the epidemiological investigation, diagnosis, evolution, and control of mycobacterial diseases is discussed.

Successful treatment of Mycobacterium terrae complex infection of the knee

Mycobacterium terrae is an unusual, ubiquitous organism that can cause clinical disease in both immunocompetent and immunocompromised hosts and can be difficult to diagnose and treat. We report a case of a 61-year-old man with a septic knee whose arthroscopy cultures grew M. terrae. The patient was successfully treated using a 6-month regimen of clarithromycin and sulfamethoxazole. Mycobacterium terrae should be considered in the differential diagnoses for monoarticular swelling and pain of unknown etiology, especially in the setting of initially negative routine microbiological cultures.

Plumbing of hospital premises is a reservoir for opportunistically pathogenic microorganisms: a review

Several bacterial species that are natural inhabitants of potable water distribution system biofilms are opportunistic pathogens important to sensitive patients in healthcare facilities. Waterborne healthcare-associated infections (HAI) may occur during the many uses of potable water in the healthcare environment. Prevention of infection is made more challenging by lack of data on infection rate and gaps in understanding of the ecology, virulence, and infectious dose of these opportunistic pathogens. Some healthcare facilities have been successful in reducing infections by following current water safety guidelines. This review describes several infections, and remediation steps that have been implemented to reduce waterborne HAIs.

Point-of-use membrane filtration and hyperchlorination to prevent patient exposure to rapidly growing mycobacteria in the potable water supply of a skilled nursing facility

BACKGROUND

Healthcare-associated outbreaks and pseudo-outbreaks of rapidly growing mycobacteria (RGM) are frequently associated with contaminated tap water. A pseudo-outbreak of Mycobacterium chelonae-M. abscessus in patients undergoing bronchoscopy was identified by 2 acute care hospitals. RGM was identified in bronchoscopy specimens of 28 patients, 25 of whom resided in the same skilled nursing facility (SNF). An investigation ruled out bronchoscopy procedures, specimen collection, and scope reprocessing at the hospitals as sources of transmission.

OBJECTIVE

To identify the reservoir for RGM within the SNF and evaluate 2 water system treatments, hyperchlorination and point-of-use (POU) membrane filters, to reduce RGM.

DESIGN

A comparative in situ study of 2 water system treatments to prevent RGM transmission.

SETTING

An SNF specializing in care of patients requiring ventilator support.

METHODS

RGM and heterotrophic plate count (HPC) bacteria were examined in facility water before and after hyperchlorination and in a subsequent 24-week assessment of filtered water by colony enumeration on Middlebrook and R2A media.

RESULTS

Mycobacterium chelonae was consistently isolated from the SNF water supply. Hyperchlorination reduced RGM by 1.5 log(10) initially, but the population returned to original levels within 90 days. Concentration of HPC bacteria also decreased temporarily. RGM were reduced below detection level in filtered water, a 3-log(10) reduction. HPC bacteria were not recovered from newly installed filters, although low quantities were found in water from 2-week-old filters.

CONCLUSION

POU membrane filters may be a feasible prevention measure for healthcare facilities to limit exposure of sensitive individuals to RGM in potable water systems.

Infectious arthritis of the knee caused by Mycobacterium terrae: a case report

Mycobacterium terrae is ubiquitous in our environment. M terrae infections most commonly involve tendon sheaths, bones, bursae, and joints. We report a case of infectious arthritis of the knee caused by M terrae in a 21-year-old man who had non-specific chronic synovitis. No organism was seen on microscopy or isolated from cultures until months later. Initially the M terrae culture was considered a contaminant and specific anti-mycobacterial treatment was not advised. The patient was commenced on suppressive therapy for persistent effusion and discomfort. Eventually, the M terrae infection was confirmed and he was commenced on clarithromycin, ciprofloxacin, and ethambutol. The triple antibiotic regimen was continued for 2 years. The knee improved but never completely settled. The patient chose to cease all antibiotic medication. The knee remained swollen and irritable, with little chance of eradicating the organism.