Non-pigmented rapidly growing mycobacteria smooth and rough colony phenotypes pathogenicity evaluated using in vitro and experimental models.

Non-pigmented rapidly growing mycobacteria (NPRGM) are widely distributed in water, soil and animals. It has been observed an increasing importance of NPRGM related-infections, particularly due to the high antimicrobial resistance. NPRGM have rough and smooth colony phenotypes, and several studies have showed that rough colony variants are more virulent than smooth ones. However, other studies have failed to validate this observation. In this study, we have performed two models, invitro and in vivo, in order to assess the different pathogenicity of these two phenotypes. We used collection and clinical strains of Mycobacteriumabscessus, Mycobacterium fortuitum and Mycobacteriumchelonae. On the invitro model (macrophages), phagocytosis was higher for M. abscessus and M. fortuitum rough colony variant strains when compared to smooth colony variants. However, we did not find differences with colonial variants of M. chelonae. Survival of Galleriamellonella larvae in the experimental model was lower for M. abscessus and M. fortuitum rough colony variants when compared with larvae infected with smooth colony variants. We did not find differences in larvae infected with M. chelonae.Results of our in vivo study correlated well with the experimental model. This fact could have implications on the interpretation of the clinical significance of the NPRGM isolate colonial variants.

Disseminated Mycobacterium chelonae infection in a patient with T-cell lymphoma.

Infections with rapidly growing mycobacteria are rare and most often seen in immunocompromised patients. We herein present the case of a 69-year-old man with a T-cell lymphoma treated by chemotherapy and mogamulizumab with a 6-month history of febrile episodes and subcutaneous nodules in both arms and arthritis of metacarpophalangeal joints. Blood cultures and DNA sequencing results demonstrated the growth of Mycobacterium chelonae. The patient was successfully treated with clarithromycin, moxifloxacin, and tobramycin, but died shortly after due to lymphoma progression.

Nontuberculous mycobacteria pathogenesis and biofilm assembly.

Nontuberculous mycobacteria (NTM) are emergent pathogens whose importance in human health has been gaining relevance after being recognized as etiological agents of opportunist infections in HIV patients. Currently, NTM are recognized as etiological agents of several respiratory and extra-respiratory infections of immune-competent individuals. The environmental nature of NTM together with the ability to assemble biofilms on different surfaces plays a key role on their pathogenesis. In the present work the ability of three fast-growing NTM (Mycobacterium smegmatis, Mycobacterium fortuitum and Mycobacterium chelonae) to persist within a model of human alveolar macrophages was evaluated. Most often human infections with NTM occur by contact with the environment. Biofilms can work as environmental reservoirs. For this reason, it was decided to evaluate the ability of NTM to assemble biofilms on different surfaces. Scanning electron microscopy was used to elucidate the biofilm structure. The ability to assemble biofilms was connected with the ability to spread on solid media known as sliding. Biofilm assembly and intracellular persistence seems to be ruled by different mechanisms.

Catheter related line sepsis resulting from Mycobacterium chelonae infection in an immunocompromised host.

Almost any species of non tuberculosis mycobacterium [NTM], including M. chelonae may be associated with nosocomial infections including catheter related sepsis, pneumonia etc. We present a case of catheter related sepsis due to M. chelonae which was treated with appropriate therapy including removal of the catheter. This case serves as a reminder to include the NTM group in the differential diagnosis of these nosocomial infections.

Mycobacteriosis in zebrafish colonies.

Mycobacteriosis, a chronic bacterial infection, has been associated with severe losses in some zebrafish facilities and low-level mortalities and unknown impacts in others. The occurrence of at least six different described species (Mycobacterium abscessus, M. chelonae, M. fortuitum, M. haemophilum, M. marinum, M. peregrinum) from zebrafish complicates diagnosis and control because each species is unique. As a generalization, mycobacteria are often considered opportunists, but M. haemophilum and M. marinum appear to be more virulent. Background genetics of zebrafish and environmental conditions influence the susceptibility of fish and progression of disease, emphasizing the importance of regular monitoring and good husbandry practices. A combined approach to diagnostics is ultimately the most informative, with histology as a first-level screen, polymerase chain reaction for rapid detection and species identification, and culture for strain differentiation. Occurrence of identical strains of Mycobacterium in both fish and biofilms in zebrafish systems suggests transmission can occur when fish feed on infected tissues or tank detritus containing mycobacteria. Within a facility, good husbandry practices and sentinel programs are essential for minimizing the impacts of mycobacteria. In addition, quarantine and screening of animals coming into a facility is important for eliminating the introduction of the more severe pathogens. Elimination of mycobacteria from an aquatic system is likely not feasible because these species readily establish biofilms on surfaces even in extremely low nutrient conditions. Risks associated with each commonly encountered species need to be identified and informed management plans developed. Basic research on the growth characteristics, disinfection, and pathogenesis of zebrafish mycobacteria is critical moving forward.

Infección Cutánea por Mycobacterium chelonae / Cutaneous infection by Micobacterium chelonae

Mycobacterium chelonae es una micobacteria atípica, de rápido crecimiento, ampliamente distribuida en la naturaleza. Germen oportunista del humano y causante de infecciones de diversa gravedad. Suele ser resistente a los métodos habituales de desinfección y esterilización. Es fundamentalpara su diagnóstico y tratamiento el aislamiento del mismo y la obtención del antibiograma, ya que presenta resistencia a diferentes antibióticos. Se presentan dos casos clínicos de infección cutánea por Mycobacterium chelonae. El primero, un paciente inmunocompetente, con aislamiento de la micobacteria por punción-aspiración de las lesiones; tratado con antibióticos según antibiograma, con curación de las mismas. El segundo, una paciente inmunocomprometida no HIV, quien fue tratada con múltiples esquemas antibióticos, criocirugía, termoterapia y resección quirúrgica de las lesiones, con respuesta parcial. El presente artículo intenta actualizar conceptos sobre esta micobacteria y sus diferentes manifestaciones clínicas según el estado inmune del paciente que infecta.

Infection of total hip prosthesis by Mycobacterium tuberculosis and Mycobacterium chelonae in a patient with rheumatoid arthritis.

Atypical mycobacterial infections of the musculoskeletal system are very rare and are generally associated with predisposing factors, such as trauma, use of corticosteroids, or an immunocompromised state. There have only been three reports of Mycobacterium chelonae prosthetic infection of which two cases were associated with total hip arthroplasty and one with total knee arthroplasty and no reports of both Mycobacterium tuberculosis and M. chelonae occurring in the same joint. We report a case of a patient with rheumatoid arthritis treated with low-dose methotrexate (15 mg/week) who developed infection with both M. tuberculosis and M. chelonae after the revision of a prosthetic hip. Joint infections by mycobacteria are clinically indistinguishable from those caused by more common bacterial pathogens and, therefore, diagnosis is often delayed. Recurrent prosthetic hip infections, particularly in immunosuppressive patients, should alert the physician to consider the possibility of both tuberculous and atypical mycobacterial infections. Obtaining appropriate cultures can be critical in making the diagnosis and directing treatment. With the increasing use of immunosuppressive agents, including TNF alpha inhibitors, it is likely that there will be an increase in the number of mycobacterial infections complicating arthroplasties.

Hypervirulence of a rough variant of the Mycobacterium abscessus type strain.

We isolated a rough variant of Mycobacterium abscessus CIP 104536T during experimental infection of mice. We show that this variant has lost the ability to produce glycopeptidolipids, is hyperlethal for C57BL/6 mice infected intravenously, and induces a strong tumor necrosis factor-alpha response by murine monocyte-derived macrophages.

Hospital outbreak of atypical mycobacterial infection of port sites after laparoscopic surgery.

A series of 145 laparoscopy port site infections due to Mycobacterium chelonae were found in 35 patients following laparoscopy at a single hospital over a six-week period. The contaminating source was ultimately identified as the rinsing water used for washing chemically disinfected instruments. The organism survived and grew within the biofilm at the bottom of disinfectant trays and within the outer sleeves of re-usable laparoscopic instruments. Remedial control measures included changing to ethylene oxide gas sterilization of laparoscopic equipment instead of chemical sterilization, thorough dismantling and manual precleaning of instruments, drying prior to gas sterilization, and random checks of environmental samples within the operating room complex for acid-fast bacilli. No further atypical mycobacterial infective episodes have occurred in the three years since the study. Awareness of this ubiquitous opportunistic organism that is not easily eradicated from the hospital environment, careful surveillance, detailed attention to disinfection methods of medical devices, and appropriate control measures are essential to prevent potential outbreaks.

Hypersensitivity pneumonitis associated with environmental mycobacteria.

A previously healthy man working as a machine operator in an automotive factory developed respiratory symptoms. Medical evaluation showed abnormal pulmonary function tests, a lung biopsy showed hypersensitivity pneumonitis, and his illness was traced to his work environment. His physician asked the employer to remove him from exposure to metalworking fluids. Symptoms reoccurred when he was later reexposed to metalworking fluids, and further permanent decrement in his lung function occurred. Investigation of his workplace showed that five of six large reservoirs of metalworking fluids (cutting oils) grew Mycobacterium chelonae (or Mycobacterium immunogenum), an organism previously associated with outbreaks of hypersensitivity pneumonitis in automaking factories. His lung function remained stable after complete removal from exposure. The employer, metalworking fluid supplier, union, and the National Institute for Occupational Safety and Health were notified of this sentinel health event. No further cases have been documented in this workplace.

Delayed post-operative wound infections due to non-tuberculous Mycobacterium.

BACKGROUND & OBJECTIVE: The non-tuberculous mycobacteria (NTM) have emerged as important opportunistic pathogens of human beings in the recent years. The NTM are rapid growing mycobacteria (RGM), which include Mycobacterium fortuitum and M. chelonae and grouped as M. fortuitum-chelonae complex. Though there are reports on isolation of NTM from various parts of India, information on its occurrence in northeastern India is lacking. We therefore undertook this preliminary investigation to report on the occurrence of NTM-associated with non-healing postoperative wound infections that did not respond to antibiotics used for pyogenic infections and having sterile routine aerobic cultures in patients from northeastern part of India. METHODS: Pus/discharge from 25 patients with delayed onset of post-operative wound infections not responding to antibiotics used for pyogenic infections were collected and examined for isolation and identification of the causative agents. RESULTS: Of the 25 pus/discharge specimens examined, 20 revealed growth of non-tuberculous Mycobacterium spp. All the isolates were identified as M. fortuitum-chelonae complex. Of these only 10 samples revealed acid-fast bacilli (AFB) on direct examination of Ziehl-Neelsen stained smears from the specimens. All cases where direct smear was positive for AFB were also positive for Mycobacterium culture. INTERPRETATION & CONCLUSION: The results of the present study indicated that non-tuberculous mycobacterial post-operative wound infection was fairly common in northeastern India. Thus, mycobacterial infections should be considered in wounds that show delayed healing and do not respond to antibiotics used for acute pyogenic infections. Further, 80 per cent of the specimens yielded the growth of AFB in cultures as against only 40 per cent positive in the ZN stained direct smears. This indicates the possibility of missing a mycobacterial wound infection if only direct smears are taken for diagnosis.

Topical antibacterial therapy for mycobacterial keratitis: potential for surgical prophylaxis and treatment.

BACKGROUND: Mycobacterium chelonae and Mycobacterium fortuitum are the 2 most commonly implicated species of nontuberculous mycobacteria in cases of bacterial keratitis. OBJECTIVES: This article summarizes available data on the in vitro antibacterial activity against M chelonae or M fortuitum of 2 agents-amikacin and clarithromycin-that have been used in the treatment of bacterial keratitis. In addition, the article reviews the in vitro activity of 5 commercially available topical ocular fluoro-quinolones (in order of availability, ciprofloxacin, ofloxacin, levofloxacin, gatifloxacin, and moxifloxacin) that may have potential in the surgical prophylaxis and treatment of keratitis caused by M chelonae or M fortuitum. METHODS: A search of the English-language literature indexed on the MEDLINE, Life Sciences, EMBASE, BIOSIS, and Pharmaprojects databases from 1966 to October 7, 2003, was conducted using the terms Mycobacterium chelonae, Mycobacterium fortuitum, bacterial keratitis, topical antibiotic therapy, ocular infection-mycobacteria, and LASIK infections. Data on the minimum concentrations at which 90% of isolates were inhibited (MIC(90)s) were reviewed and compared. RESULTS: In the literature reviewed, the MIC(90) against M fortuitum was from 1 to 16 microg/mL for amikacin, from /=8 microg/mL for clarithromycin, from 0.1 to 1 microg/mL for ciprofloxacin, from 0.5 to 3.13 microg/mL for ofloxacin, and

Infections with rapidly growing mycobacteria: report of 20 cases.

OBJECTIVES: A series of cases infected with rapidly growing mycobacteria was studied to determine the spectrum of disease, antimicrobial susceptibility, treatment, and outcome. METHODS: The cases identified as infections with rapidly growing mycobacteria in Ramathibodi Hospital from January 1993 to December 1999 were retrospectively studied. RESULTS: Most of the cases had no underlying disease. Only two cases were HIV-infected patients. The presenting clinical features were lymphadenitis (seven cases), skin and/or subcutaneous abscess (seven cases), localized eye infection (four cases), pulmonary infection (one case), and chronic otitis media (one case). Four of seven cases with lymphadenitis had Sweet's syndrome, and one had psoriasis as an associated skin manifestation. Anemia was present in five cases, and improved with treatment of the primary disease. The organisms were Mycobacterium chelonae/abscessus group (17 cases) and Mycobacterium fortuitum group (three cases). Susceptibility patterns of the organisms showed susceptibility to amikacin, netilmicin, and imipenem. M. fortuitum group was susceptible to more antibiotics than M. chelonae/abscessus group. The clinical responses corresponded to the antimicrobial susceptibility. Combinations of two or more drugs were used for the medical treatment. Surgical resection was performed where possible, to reduce the load of the organism, especially in cases with very resistant organisms. CONCLUSIONS: Infections with rapidly growing mycobacteria can occur in apparently normal hosts. The clinical syndrome is variable. The pathology is nonspecific. Clinical responses varied, but seemed to correlate with the in vitro susceptibility result. More studies are needed to enable us to deal with this infection effectively.

Lipomannans, but not lipoarabinomannans, purified from Mycobacterium chelonae and Mycobacterium kansasii induce TNF-alpha and IL-8 secretion by a CD14-toll-like receptor 2-dependent mechanism.

Lipoarabinomannans (LAMs) are glycolipids from the mycobacterial cell wall that exhibit various biological activities, including proinflammatory and anti-inflammatory responses. However, little is known about the properties of lipomannans (LMs), considered to be precursors of LAMs. In this study, we provide evidence that LMs purified from Mycobacterium chelonae and a clinical strain of Mycobacterium kansasii stimulated mRNA expression and secretion of TNF-alpha and IL-8 from human macrophage-like differentiated THP-1 cells. In contrast to LMs, LAMs were not able to induce a significant cytokine-inducing effect. The mechanism of activation by LMs was investigated using various Abs raised against surface receptors for multiple bacterial products. The presence of anti-CD14 or anti-Toll-like receptor 2 (TLR2) Abs profoundly affected production of TNF-alpha and IL-8, suggesting that both CD14 and TLR2 participate in the LM-mediated activation process. Furthermore, stimulation of cells was dependent on the presence of the LPS-binding protein, a plasma protein that transfers glycolipids to CD14. Chemical degradation of the arabinan domain of mannose-capped LAM from M. kansasii, which presented no cytokine-eliciting effect, restored the cytokine-inducing activity at a level similar to those of LMs. These results support the hypothesis that the presence of an arabinan in LAMs prevents the interaction of these glycolipids with TLR2/CD14 receptors. In addition, we found that phosphatidylinositol dimannosides isolated from M. kansasii did not induce cytokine secretion. This study suggests that LMs isolated from different mycobacterial species participate in the immunomodulation of the infected host and that the D-mannan core of this glycolipid is essential for this function.

Mycobacteriosis in Atlantic salmon farmed in British Columbia.

Mycobacterium chelonae was identified as the cause of incidental mortality in Atlantic salmon smolts following introduction to seacages. Source of infection was not confirmed. Polymerase chain reaction was a useful method of detecting and speciating the genus Mycobacterium in infected stocks. Clinical management and public health implications of infection are discussed.

An outbreak of hypersensitivity pneumonitis at a metalworking plant: a longitudinal assessment of intervention effectiveness.

The authors describe a longitudinal assessment of intervention effectiveness in response to an outbreak of hypersensitivity pneumonitis (HP) at a metalworking facility. Thirty-five (29%) of the plant's 120 production workers were given a clinical diagnosis of HP during the two years of the investigation. Although quantitative exposure assessment tools were of limited utility, the investigators successfully used qualitative observations and the patients' return-to-work experiences to iteratively evaluate their exposure control recommendations. Recommended interventions included improving metalworking fluid management practices, enclosing selected metalworking fluid machining operations, eliminating mist cooling, exhausting two additional water-based industrial processes, increasing general dilution ventilation, and worker training. As of November 1999, 26 months into the outbreak, 51 percent (18) of the employees with a clinical diagnosis of hypersensitivity pneumonitis had been able to return to work. The symptom onset of the 35 workers who were given a clinical diagnosis of hypersensitivity pneumonitis during the two-year study period predated the implementation of the interventions. The collaboration of a multidisciplinary team appears to have allowed for successful intervention in this setting. A specific etiological agent(s) associated with the outbreak was not confirmed during the investigation. An acid fast isolate identified as being in the Mycobacterium chelonae group was detected in only one of the submitted metalworking fluid (MWF) sump samples. Longitudinally, there was a statistically significant difference in MWF sump bacteria (X(2) = 286.4, df = 17, p <.0001) and MWF sump fungi (X(2) = 28.1, df = 7, p <.0002). Measured oil mist air levels did not exceed the Occupational Safety and Health Administration's (OSHA's) permissible exposure limit (PEL), and in fact, did not exceed 0.5 mg/m(3).

Large-scale outbreak of infection with Mycobacterium chelonae subsp. abscessus after penicillin injection.

An outbreak of infection with Mycobacterium chelonae subsp. abscessus after the injection of penicillin in 86 patients attending a factory hospital is reported. The bacterium was isolated both from lids and from the soil where the drug was stored. Molecular analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of whole-cell proteins and plasmids revealed a pattern identical to that of the strains isolated from the wounds. The source of the infections was soil contamination of the vial lids and was caused by improper use and sterilization of penicillin vials.