Fatal pulmonary infection with Mycobacterium fortuitum in cystic fibrosis

High rates of Mycobacterium fortuitum isolation in respiratory samples from Iranian patients with suspected tuberculosis: is it clinically important?

PURPOSE

Although Mycobacterium fortuitum (M. fortuitum) is not an organism rarely isolated from respiratory samples, its clinical importance is still not fully understood, which therefore prompted our current study.

METHODOLOGY

We evaluated respiratory samples from 6800 patients with suspected tuberculosis from May 2014 to May 2016, for the detection of M. fortuitum using phenotypic and genotyping methods.Results/Key findings. Of the 40 patients with M. fortuitum lung disease, 35 had two or more positive culture results. The mean age of these 35 patients was 50.7±18.4 years, and 20 (57.1 %) were men. Sputum (68.6 %), haemoptysis (51.4 %), cough (45.7 %) and gastroesophageal disease (22.9 %) were the major presenting symptoms. Cystic fibrosis, other bacterial lung diseases and lung cancer were the main underlying pulmonary diseases. Five patients (12.5 %) were human immunodeficiency virus (HIV) positive. The most common chest X-ray findings were reticulonodular opacities (53.3 %). Multivariate logistic regression analysis revealed that cigarette smoking history (OR 0.334, 95 % CI 0.125-0.843, P=0.048) and underlying lung disease (OR 0.393, 95 % CI 0.216-0.588, P=0.023) were significant predictors for positive M. fortuitum infection.

CONCLUSION

These results demonstrated the high frequency of M. fortuitum in respiratory samples and that this bacterium causes transient infection or colonization in patients with underlying pulmonary conditions, such as cystic fibrosis and cigarette smoking-induced. Additionally, it appears that infection with M. fortuitum is particularly common and may be important in patients with HIV.

Nontuberculous mycobacteria: the changing epidemiology and treatment challenges in cystic fibrosis

PURPOSE OF REVIEW

Although patients with cystic fibrosis (CF) face numerous infectious pathogens over the course of their lifespan, increasing attention has recently been paid to nontuberculous mycobacteria (NTM). As reported prevalence rates rise across many countries such as the United States, the ability to recognize disease caused by NTM and subsequently treat such disease has become increasingly important. This review summarizes new observations on the epidemiology of NTM in CF as well as key elements to consider during the treatment phase.

RECENT FINDINGS

Although overall rates of NTM isolation appear to be increasing, particular concern has focused on the emerging predominance of Mycobacterium abscessus. New data suggest that chronic macrolide therapy now part of routine CF care has contributed to this rise; however, these have yet to be confirmed prospectively. Transmission of M. abscessus between CF patients has also now been described through the use of genome sequencing. Although the greater virulence of M. abscessus makes it a challenging species to treat, identification of the subspecies type can now determine the presence of inducible macrolide resistance, thereby helping to guide treatment.

SUMMARY

Given increasing prevalence rates, clinicians should maintain a high level of suspicion for NTM as disease-causing organisms in CF, particularly for M. abscessus. New knowledge regarding this species, however, can help to tailor appropriate therapy.

Nontuberculous Mycobacterial Pulmonary Infection in Patients with Cystic Fibrosis

The prevalence of nontuberculous mycobacteria (NTM) recovered from patients with cystic fibrosis (CF) appears to be increasing, probably related to improved surveillance and microbiological procedures and an increase in the life expectancy of patients with CF. The distinction between active lung infection and colonization is often difficult to assess in patients with CF because of the marked overlap in the clinical and radiological presentation of CF lung disease and lung disease caused by NTM infection. The possibility of active NTM lung infection should be considered in those patients with compatible radiographic changes and/or progressive deterioration in lung function who do not improve with specific antibiotic therapy and who have repeatedly positive sputum cultures and smears for NTM. Patients with repeatedly positive results of acid-fast smears are more likely to be infected than colonized. Pseudomonas overgrowth may confuse the results of sputum and bronchoalveolar lavage fluid cultures. Decontamination of respiratory samples from patients with CF with 5% oxalic acid results in improved bacteriological recovery of NTM. Skin tests are of limited value as a screening tool for NTM. Since the course of NTM lung infection is often slow, careful follow-up with repeated sputum cultures, chest radiographs and computed tomography (CT) scans may be needed. Treatment of NTM lung disease in patients with CF presents great difficulties because of abnormal gastrointestinal drug absorption and pharmacokinetics in this patient population. Treatment varies according to the mycobacterial species isolated. Long-term multidrug regimens including rifampin (rifampicin) and ethambutol are usually required. Monitoring serum drug levels is a useful indicator of correct dosage in order to prevent adverse effects due to potential drug interactions and altered pharmacokinetics in patients with CF.

Trends of mycobacterial clinical isolates in Taiwan

Non-tuberculous mycobacteria (NTM) can cause chronic pulmonary infection, however, NTM infection is generally overlooked. This retrospective study analyzed the frequencies of Mycobacterium tuberculosis complex (MTBC) and NTM clinical isolates from 99 200 specimens of patients suspected with pulmonary mycobacterial infection in Taiwan from 2002-2007. A total of 8024 mycobacterial isolates, including 5349 MTBC and 2675 NTM, were obtained from the 99 200 specimens in the study period. The overall mycobacterial isolation rate was 8.09% (8024/99 200), and the overall MTBC and NTM isolation rate was 5.39% (5349/99 200) and 2.7% (2675/99 200), respectively. Notably, the prevalence of NTM isolates among the identified mycobacteria strains was increased 2.6 fold from 2002 (17.54%, 147/838) to 2007 (45.80%, 659/1439). The frequencies of MTBC and NTM isolates showed a reciprocal trend: the NTM isolation rates were steadily increasing while the overall mycobacterial isolation rates remained stable over the study period. Our results suggest that the diagnosis, identification and susceptibility tests for NTM should be standardized and integrated in clinical routines, for providing the information of NTM infection and prescribing clinical treatment in a more precise and efficient way to reduce the increasing NTM in the studied area.

Clinical significance of microbial infection and adaptation in cystic fibrosis

A select group of microorganisms inhabit the airways of individuals with cystic fibrosis. Once established within the pulmonary environment in these patients, many of these microbes adapt by altering aspects of their structure and physiology. Some of these microbes and adaptations are associated with more rapid deterioration in lung function and overall clinical status, whereas others appear to have little effect. Here we review current evidence supporting or refuting a role for the different microbes and their adaptations in contributing to poor clinical outcomes in cystic fibrosis.

Atypical mycobacterial infection in patients with cystic fibrosis: update on clinical microbiology methods

While patients with cystic fibrosis (CF) have had dramatic improvement in their survival rates, this has been accompanied by the emergence of more virulent pathogens such as Pseudomonas aeruginosa and Burkholderia cepacia complex organisms. In addition, there has been emergence of organisms of increasing clinical significance such as the nontuberculous mycobacterial (NTM). Although TB infection in patients with CF is extremely uncommon, there is growing concern with regard to atypical Mycobacterium spp, in particular Mycobacterium abscessus. Many methods of decontamination of sputum, which have been adapted from TB methodologies, are ineffective; as shown by the overgrowth of P. aeruginosa, it is essential that decontamination methods are optimized to overcome this. Establishing optimal methods of isolation and determining accurate levels of prevalence is of importance as, although NTM may be isolated relatively infrequently in CF populations, their clinical status in pulmonary disease is now beginning to emerge.

Clinical significance of Mycobacterium fortuitum isolated from respiratory specimens

BACKGROUND

Although Mycobacterium fortuitum is not an uncommon organism among the non-tuberculous mycobacteria isolated from respiratory specimens, its clinical significance had not been well studied.

METHODS

We identified all patients whose respiratory specimens were positive for M. fortuitum between January 2003 and December 2005. Among 182 patients whose specimens were positive for M. fortuitum, 26 were positive at least twice. We retrospectively reviewed their characteristics, and clinical courses.

RESULTS

Of the 26 patients, 15 had two positive culture results for M. fortuitum; the other 11 had three or more. Sixteen patients were male and the median age was 61.5 years. Major presenting symptoms were cough (65%) and sputum (58%). Most patients had known underlying lung diseases, including prior tuberculosis (54%), lung cancer (15%), idiopathic pulmonary fibrosis (15%), and other mycobacterial lung disease (15%). The most common CT findings were bronchiectasis (80%). Only one patient received specific prolonged antibiotic therapy against M. fortuitum infection; the other 25 did not. No patients showed clinical aggravation during the follow-up period, although in five patients their underlying lung diseases continued to progress. The median follow-up duration was 12.5 months and none of the patients whose sputum specimens were available had persistent positive cultures for M. fortuitum.

CONCLUSION

M. fortuitum usually causes colonization or transient infection in patients with underlying lung disease, such as prior tuberculosis or bronchiectasis. The majority of patients may not need to receive prolonged antibiotic therapy for M. fortuitum isolates.

Nontuberculous mycobacteria. II: nested-cohort study of impact on cystic fibrosis lung disease

The prevalence of nontuberculous mycobacteria (NTM) is high (approximately 13%) in sputum of patients with cystic fibrosis (CF), but the impact on lung disease is unknown. We followed 60 incident NTM-positive and 99 culture-negative patients with CF for 15 months and assessed clinical impact of NTM by FEV1 and high-resolution computed tomography (HRCT) of the chest. Mycobacterium avium complex was seen in 75% of NTM-positive subjects. The annual rate of decline in FEV1 was not different among control versus NTM-positive subjects who did not, or did, meet American Thoracic Society microbiologic criteria for NTM disease (3 +/- 1, 3 +/- 2, and 5 +/- 2%, respectively). More subjects with three or more positive cultures for NTM had two or more characteristic findings on entry HRCT (60%, 9/15) as compared with subjects with two positive cultures or less (32%) or negative cultures (19%; p < 0.02). All subjects with three or more positive cultures and exit HRCTs (n = 6) showed progression of HRCT findings, whereas only 17% of subjects with two positive cultures or less had progression (p = 0.0006). In summary, no significant short-term effect on FEV1 was detected in patients with multiple positive NTM cultures, but an abnormal HRCT was predictive of progression. Patients with CF and multiple positive NTM cultures, characteristic HRCT findings, and progression of HRCT changes should be monitored closely and considered for antimycobacterial therapy.

Clinical and taxonomic status of pathogenic nonpigmented or late-pigmenting rapidly growing mycobacteria

The history, taxonomy, geographic distribution, clinical disease, and therapy of the pathogenic nonpigmented or late-pigmenting rapidly growing mycobacteria (RGM) are reviewed. Community-acquired disease and health care-associated disease are highlighted for each species. The latter grouping includes health care-associated outbreaks and pseudo-outbreaks as well as sporadic disease cases. Treatment recommendations for each species and type of disease are also described. Special emphasis is on the Mycobacterium fortuitum group, including M. fortuitum, M. peregrinum, and the unnamed third biovariant complex with its recent taxonomic changes and newly recognized species (including M. septicum, M. mageritense, and proposed species M. houstonense and M. bonickei). The clinical and taxonomic status of M. chelonae, M. abscessus, and M. mucogenicum is also detailed, along with that of the closely related new species, M. immunogenum. Additionally, newly recognized species, M. wolinskyi and M. goodii, as well as M. smegmatis sensu stricto, are included in a discussion of the M. smegmatis group. Laboratory diagnosis of RGM using phenotypic methods such as biochemical testing and high-performance liquid chromatography and molecular methods of diagnosis are also discussed. The latter includes PCR-restriction fragment length polymorphism analysis, hybridization, ribotyping, and sequence analysis. Susceptibility testing and antibiotic susceptibility patterns of the RGM are also annotated, along with the current recommendations from the National Committee for Clinical Laboratory Standards (NCCLS) for mycobacterial susceptibility testing.

Imaging of Non-tuberculous (Atypical) Mycobacterial Pulmonary Infection

Pulmonary infections due to mycobacterial organisms are increasing in incidence. Non-tuberculous (atypical) mycobacteria (NTM) represent a significant proportion of mycobacterial infections and may prove difficult to diagnose due to their non-specific clinical and radiographic presentations. An increasing volume of radiological data is now available for the more common non-tuberculous mycobacterial infections, and we have summarized the imaging features found in such cases, identifying radiographic features that would favour the diagnosis of a non-tuberculous mycobacterium and that, in some cases, suggest a specific organism.

Non-tuberculous mycobacterial pulmonary infections

Pulmonary disease due to EM occurs worldwide, and its prevalence has increased as a consequence of the HIV pandemic. It is not often detected in the tropics owing to a lack of laboratory facilities, but when sought it has been found. In addition to HIV infection certain occupations such as mining render the work force more susceptible to disease and calls for a revision of working conditions. Resolution by therapy can be achieved in many cases. As the prevalence of TB diminishes worldwide--and hopefully it will in the wake of the resurgence of interest and the widespread application of the World Health Organization's Directly Observed Therapy Short Course (DOTS) strategy--disease due to EM will become relatively more important and will necessitate revised strategies in clinical, microbiological, and public health approaches to mycobacterial disease.

Mycobacterium abscessus infection in cystic fibrosis. Colonization or infection?

We present a case of a patient with cystic fibrosis who was thought to be colonized with Mycobacterium abscessus for 13 yr prior to developing clinically apparent mycobacterial infection. However, histologic evidence indicated that invasive mycobacterial disease was present from the onset. While accepting that chronic endobronchial colonization with atypical mycobacteria may occur in patients with cystic fibrosis, the repeated isolation of mycobacteria from the sputum of these patients should alert the clinician to the possibility of indolent disease. Early consideration of treatment for this infection should occur in any patient with cystic fibrosis in whom there is an unexplained deterioration in lung function. The recent introduction of high dose ibuprofen raises concerns about its possible contribution to the progression of the infection.

Mycobacterial lung disease in cystic fibrosis: a prospective study

BACKGROUND

Patients with cystic fibrosis (CF) may be predisposed to airway infections with unusual organisms, such as mycobacteria. The aim of the study was to determine the incidence and clinical picture of mycobacterial infection in CF children.

METHODS

At least 2 acid-fast bacillus (AFB) smears and mycobacterial cultures were performed on a prospective basis on 682 sputum specimens from 106 patients during a 1-year period.

RESULTS

Thirty-three percent of the cultures were contaminated with other bacteria. Seven children had at least one sputum culture positive for one mycobacterium. Five children had only one positive AFB culture. Their clinical status and lung function remained stable during follow-up. Two teenagers with severe lung disease had several positive AFB smears and cultures for Mycobacterium chelonae and Mycobacterium abscessus. The isolation of M. chelonae and M. abscessus was associated with a clinical and functional decline. Clarithromycin treatment resulted in temporary improvement with the disappearance of the mycobacteria after 6 months of treatment. This prospective study shows an incidence of 2.3% for positive cultures. The prevalence was 6.6% for mycobacterial colonization but only 1.9% for mycobacterial lung disease in our pediatric population.

CONCLUSIONS

We recommend performing AFB smears and cultures in CF children with severe lung disease and/or during a lung exacerbation. In these patients persistence of M. chelonae or M. abscessus in sputum should lead to consideration of treatment with clarithromycin.

Fatal pulmonary infection due to Mycobacterium fortuitum

Environmental (atypical, opportunist, other) mycobacteria were first isolated nearly a century ago. The classification of these "other than Mycobacterium tuberculosis" organisms was initially chaotic until Runyon proposed a scheme of four groups in 1959. Mycobacterium fortuitum is a member of group IV: Rapid growers. These ubiquitous terrestrial and aquatic forms contaminate water supplies, reagents, and clinical samples. They may colonise the respiratory systems of patients whose local defence mechanisms have been impaired or those with congenital and acquired immune defects. They can also cause disease in immunocompetent individuals. There have been fewer than 20 published cases of pulmonary infection caused by M fortuitum. A further case is reported of fatal pulmonary infection in an elderly patient with long standing chronic obstructive airways disease (COAD). He had left upper zone shadowing on chest radiography and lung abscesses at post mortem examination yielded only M fortuitum.

Nontuberculous mycobacteria in adult patients with cystic fibrosis

Because patients with cystic fibrosis (CF) may be predisposed to airway infections with unusual microorganisms, we screened the sputum of adult CF patients for mycobacterial organisms. Acid-fast bacilli (AFB) smears and mycobacterial culture were performed on 297 sputum specimens from 87 patients. Cultures for mycobacteria were frequently overgrown with other bacteria; 22.6 percent of cultures were contaminated. Despite this limitation of mycobacterial culture, 17 patients had at least one positive culture for a Mycobacterium other than tuberculosis (MOTT). Eleven patients were positive for Mycobacterium avium-intracellulare (MAI), two for MAI and M chelonei, three for M chelonei, and one for M fortuitum. None was positive for M tuberculosis. Patients with CF with MOTT were similar to patients with CF without MOTT; only a slightly different (older) age distribution was recognized. The clinical significance of MOTT was difficult to determine in any individual patient, but patients with positive AFB smears appeared more likely to suffer pathogenic effects. We conclude that MOTT is frequently recovered from adult CF patients in the southeastern United States. A specific risk factor for colonization and/or pathogenic infection in this patient group was not evident. The general prevalence and clinical pathogenesis in CF patients in the United States remains to be determined.

Prospective study of mycobacterial infections in patients with cystic fibrosis

Fifty four patients with cystic fibrosis, aged 3-67 years, were studied prospectively for pulmonary mycobacterial infection. Sputum smears and cultures were carried out and intradermal skin tests performed. Mycobacteria were cultured from six patients in association with clinical deterioration; four patients had positive direct smears. Mycobacterium tuberculosis, M aviumintracellulare, M kansasii, and M gordonae were isolated. There were no deaths and all improved with chemotherapy. A third of the other 48 patients had positive skin test responses (greater than 6 mm) to purified protein derivative (PPD) tuberculin and 21 to one or more antigens prepared from non-tuberculous mycobacteria. Sensitisation increased with age; before the age of 11 only one patient had a positive response to PPD tuberculin and none to any other antigen. This was less than in healthy control subjects of similar age. After age 11 the reactions in sensitised patients were stronger than in positive healthy control subjects. Our study indicates that it is important to consider mycobacterial infection in patients with cystic fibrosis who deteriorate without obvious cause.

Fatal infection with Mycobacterium fortuitum associated with oesophageal achalasia

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