Proficiency testing of clinical microbiology laboratories using modified decontamination procedures for detection of nontuberculous mycobacteria in sputum samples from cystic fibrosis patients. The Nontuberculous Mycobacteria in Cystic Fibrosis Study Group

Culture independent markers of nontuberculous mycobacterial (NTM) lung infection and disease in the cystic fibrosis airway

Nontuberculous mycobacteria (NTM) are opportunistic pathogens that affect a relatively small but significant portion of the people with cystic fibrosis (CF), and may cause increased morbidity and mortality in this population. Cultures from the airway are the only test currently in clinical use for detecting NTM. Culture techniques used in clinical laboratories are insensitive and poorly suited for population screening or to follow progression of disease or treatment response. The lack of sensitive and quantitative markers of NTM in the airway impedes patient care and clinical trial design, and has limited our understanding of patterns of acquisition, latency and pathogenesis of disease. Culture-independent markers of NTM infection have the potential to overcome many of the limitations of standard NTM cultures, especially the very slow growth, inability to quantitate bacterial burden, and low sensitivity due to required decontamination procedures. A range of markers have been identified in sputum, saliva, breath, blood, urine, as well as radiographic studies. Proposed markers to detect presence of NTM or transition to NTM disease include bacterial cell wall products and DNA, as well as markers of host immune response such as immunoglobulins and the gene expression of circulating leukocytes. In all cases the sensitivity of culture-independent markers is greater than standard cultures; however, most do not discriminate between various NTM species. Thus, each marker may be best suited for a specific clinical application, or combined with other markers and traditional cultures to improve diagnosis and monitoring of treatment response.

Nontuberculous Mycobacterial Infections in Cystic Fibrosis

Nontuberculous mycobacteria (NTM) are important pathogens, with a longitudinal prevalence of up to 20% within the cystic fibrosis (CF) population. Diagnosis of NTM pulmonary disease in people with CF (pwCF) is challenging, as a majority have NTM infection that is transient or indolent, without evidence of clinical consequence. In addition, the radiographic and clinical manifestations of chronic coinfections with typical CF pathogens can overlap those of NTM, making diagnosis difficult. Comprehensive care of pwCF must be optimized to assess the true clinical impact of NTM and to improve response to treatment. Treatment requires prolonged, multidrug therapy that varies depending on NTM species, resistance pattern, and extent of disease. With a widespread use of highly effective modulator therapy (HEMT), clinical signs and symptoms of NTM disease may be less apparent, and sensitivity of sputum cultures further reduced. The development of a disease-specific approach to the diagnosis and treatment of NTM infection in pwCF is a research priority, as a lifelong strategy is needed for this high-risk population.

Host and pathogen response to bacteriophage engineered against Mycobacterium abscessus lung infection

Two mycobacteriophages were administered intravenously to a male with treatment-refractory Mycobacterium abscessus pulmonary infection and severe cystic fibrosis lung disease. The phages were engineered to enhance their capacity to lyse M. abscessus and were selected specifically as the most effective against the subject's bacterial isolate. In the setting of compassionate use, the evidence of phage-induced lysis was observed using molecular and metabolic assays combined with clinical assessments. M. abscessus isolates pre and post-phage treatment demonstrated genetic stability, with a general decline in diversity and no increased resistance to phage or antibiotics. The anti-phage neutralizing antibody titers to one phage increased with time but did not prevent clinical improvement throughout the course of treatment. The subject received lung transplantation on day 379, and systematic culturing of the explanted lung did not detect M. abscessus. This study describes the course and associated markers of a successful phage treatment of M. abscessus in advanced lung disease.

Breath biomarkers associated withnontuberculosis mycobacteriadisease status in persons with cystic fibrosis: a pilot study

Pulmonary infections caused by mycobacteria cause significant mortality and morbidity in the human population. Diagnosing mycobacterial infections is challenging. An infection can lead to active disease or remain indolent with little clinical consequence. In patients with pulmonarynontuberculosis mycobacteria(PNTM) identification of infection and diagnosis of disease can take months to years. Our previous studies showed the potential diagnostic power of volatile molecules in the exhaled breath samples to detect active pulmonaryM. tuberculosisinfection. Herein, we demonstrate the ability to detect the disease status of PNTM in the breath of persons with cystic fibrosis (PwCF). We putatively identified 17 volatile molecules that could discriminate between active-NTM disease (n= 6), indolent patients (n= 3), and those patients who have never cultured an NTM (n= 2). The results suggest that further confirmation of the breath biomarkers as a non-invasive and culture-independent tool for diagnosis of NTM disease in a larger cohort of PwCF is warranted.

ATS Core Curriculum 2021. Pediatric Pulmonary Medicine: Pulmonary Infections

The following is a concise review of the Pediatric Pulmonary Medicine Core reviewing pediatric pulmonary infections, diagnostic assays, and imaging techniques presented at the 2021 American Thoracic Society Core Curriculum. Molecular methods have revolutionized microbiology. We highlight the need to collect appropriate samples for detection of specific pathogens or for panels and understand the limitations of the assays. Considerable progress has been made in imaging modalities for detecting pediatric pulmonary infections. Specifically, lung ultrasound and lung magnetic resonance imaging are promising radiation-free diagnostic tools, with results comparable with their radiation-exposing counterparts, for the evaluation and management of pulmonary infections. Clinicians caring for children with pulmonary disease should ensure that patients at risk for nontuberculous mycobacteria disease are identified and receive appropriate nontuberculous mycobacteria screening, monitoring, and treatment. Children with coronavirus disease (COVID-19) typically present with mild symptoms, but some may develop severe disease. Treatment is mainly supportive care, and most patients make a full recovery. Anticipatory guidance and appropriate counseling from pediatricians on social distancing and diagnostic testing remain vital to curbing the pandemic. The pediatric immunocompromised patient is at risk for invasive and opportunistic pulmonary infections. Prompt recognition of predisposing risk factors, combined with knowledge of clinical characteristics of microbial pathogens, can assist in the diagnosis and treatment of specific bacterial, viral, or fungal diseases.

Prevalence of rifampicin resistance tuberculosis among HIV/TB coinfected patients in Benue State, Nigeria

Introduction

the emergence of HIV/TB co-infection has changed the global health landscape globally, particularly in sub-Saharan Africa and Asia with a high prevalence rate. It has further worsened and compound patient diagnosis, treatment/management approach and infection control. Rifampicin resistance TB (RR-TB) is a good indicator of treatment failure and infection control in the community. This study determines the prevalence of RR-TB among HIV/TB coinfected patients in Benue State, Nigeria.

Methods

the case-control study was carried out at Federal Medical Centre, Makurdi and General Hospital, Otupko, between January 2017 and February 2018. One thousand and ten suspected tuberculosis and HIV patients were enrolled in the study, diagnosed according to WHO guidelines. Sputum samples were collected and then analyzed by acid-fast bacilli smear test and GeneXpert MTB/RIF assay.

Results

overall prevalence of tuberculosis by acid-fast test was 74 (7.3%), 171 (16.93%) by GeneXpert assay and 2.18% by RR-TB test respectively. Significant difference was observed between the detection technique and demographic variables, high prevalence among urban patient compared to rural (8.85%vs 5.40%; X²= 4.38; P = 0.036) and ethnic background of the patients (X²= 23.21; P = 0.000) by acid fast test. With GeneXpert, high prevalence recorded among patient within age-group15-45years (X²= 8.01; P = 0.046) and ethnic group (X²= 6.30; P = 0.044). The occurrence of HIV/TB co-infection was less associated with Idoma ethnic group (COR; 0.440; 95% C.I; 0.246 - 0.786).

Conclusion

the relatively high prevalence of HIV/TB co-infection and RR-TB is a tremendous public health threat, considering society's attendant implication. Further surveillance studies are needed to evaluate the situation in Benue State better.

Culturing Mycobacteria

Building upon the foundational research of Robert Koch, who demonstrated the ability to grow Mycobacterium tuberculosis for the first time in 1882 using media made of coagulated bovine serum, microbiologists have continued to develop new and more efficient ways to grow mycobacteria. Presently, all known mycobacterial species can be grown in the laboratory using either axenic culture techniques or in vivo passage in laboratory animals. This chapter provides conventional protocols to grow mycobacteria for diagnostic purposes directly from clinical specimens, as well as in research laboratories for scientific purposes. Detailed protocols used for production of M. tuberculosis in large scale (under normoxic and hypoxic conditions) in bioreactors and for production of obligate intracellular pathogens such as Mycobacterium leprae and "Mycobacterium lepromatosis" using athymic nude mice and armadillos are provided.

Clinical relevance and diagnosis of nontuberculous mycobacterial pulmonary disease in populations at risk

The lungs are the most common disease site of nontuberculous mycobacteria (NTM). However, the isolation of NTM in a respiratory specimen does not indicate lung disease (LD). Differentiation between NTM colonization and NTM-LD remains challenging. In this brief review, we summarize the clinical impact of NTM-LD on morbidity and mortality in high-risk populations. The diagnosis criteria for NTM-LD-including clinical features, radiological presentations, and microbiological evidence-are also reviewed, according to the latest American Thoracic Society (ATS)/Infectious Disease Society of America (IDSA) guideline and the British Thoracic Society (BTS) guideline. However, the diagnosis of NTM-LD does not necessitate the initiation of anti-NTM treatment. Both environmental, host, and bacterial factors should be considered to identify patients that require NTM-LD treatment.

Bacterial Infections and the Respiratory Microbiome

Cystic fibrosis (CF) is a genetic, multisystem disease due to defects in the cystic fibrosis transmembrane conductance regulator (CFTR) protein, an anion channel responsible for chloride and bicarbonate trafficking. Although this channel is expressed in many tissues, its impaired function in airway epithelial cells leads to hyperviscous mucous secretions impeding effective mucociliary clearance. Impaired clearance of inhaled microorganisms results in the establishment of chronic infection, triggering an overexaggerated inflammatory response. The resulting release of inflammatory cytokines and enzymes causes pulmonary damage in the form of bronchiectasis, further impairing mucociliary action, forming a vicious cycle. Subsequent respiratory failure remains the leading cause of death in individuals with CF.

Disease caused by non-tuberculous mycobacteria in children with cystic fibrosis

Non-tuberculous mycobacterial (NTM) (especially M. abscessus complex) infections pose a considerable challenge in the management of lung disease in patients with cystic fibrosis (CF). The apparent increase in prevalence is likely multifactorial. Emergent evidence of patient-to-patient transmission and isolation of highly resistant strains is a concern for all CF centers around the world. Treatment is often long and burdensome with multiple agents. Treatment side effects are frequent and can cause significant morbidity. Although consensus guidelines provide some direction, many units are faced with the challenges of: finding drug combinations for highly resistant strains; dealing with interruptions of treatment; discussing additional facilitating procedures in the form of gastrostomy and long-term vascular access devices; as well as supporting families emotionally and psychologically through the process.

Nontuberculous Mycobacterial Infections in Cystic Fibrosis

Nontuberculous mycobacteria (NTM) are important emerging cystic fibrosis (CF) pathogens, with estimates of prevalence ranging from 6% to 13%. Diagnosis of NTM disease in patients with CF is challenging, as the infection may remain indolent in some, without evidence of clinical consequence, whereas other patients suffer significant morbidity and mortality. Treatment requires prolonged periods of multiple drugs and varies depending on NTM species, resistance pattern, and extent of disease. The development of a disease-specific approach to the diagnosis and treatment of NTM infection in CF patients is a research priority, as a lifelong strategy is needed for this high-risk population.

Surgery in nontuberculous mycobacteria pulmonary disease

Medical treatment of pulmonary nontuberculous mycobacteria (NTM) disease has highly variable outcomes. Despite the use of multiple antibiotics, sputum clearance is often difficult to achieve, especially in cases with macrolide resistant NTM infection. Immunocompromised patients and those with structural lung disease are at increased risk, although occurrence in immunocompetent patients without structural lung disease is well recognised. Most pulmonary NTM disease involves Mycobacterium avium complex (MAC), but with enhanced identification multiple species have now been recognised as opportunistic pathogens. The observed increase in NTM disease, especially infection with multidrug-resistant Mycobacterium abscessus complex, is probably multifactorial. Surgery has been used as adjuvant treatment in patients with 1) focal disease that can be removed or 2) bothersome symptoms despite medical treatment that can be ameliorated. Early post-surgical mortality is low, but long-term morbidity and mortality are highly dependent on the degree of lung involvement and the residual lung function, the potency of medical treatment and the type of surgical intervention. In conjunction with antibiotic therapy, reported post-surgical sputum clearance was excellent, although publication bias should be considered. Bronchopleural fistulae were problematic, especially in pneumonectomy cases. Study results support the use of minimal resection surgery, in a carefully selected subgroup of patients with focal disease or persistent symptoms.

Educational aims

To critically review the literature describing the use of surgery in the treatment of pulmonary disease caused by nontuberculous mycobacteria (NTM).To assess the outcomes and complications observed with different surgical approaches used in the treatment of pulmonary NTM disease.

US Cystic Fibrosis Foundation and European Cystic Fibrosis Society consensus recommendations for the management of non-tuberculous mycobacteria in individuals with cystic fibrosis

Non-tuberculous mycobacteria (NTM) are ubiquitous environmental organisms that can cause chronic pulmonary infection, particularly in individuals with pre-existing inflammatory lung disease such as cystic fibrosis (CF). Pulmonary disease caused by NTM has emerged as a major threat to the health of individuals with CF but remains difficult to diagnose and problematic to treat. In response to this challenge, the US Cystic Fibrosis Foundation (CFF) and the European Cystic Fibrosis Society (ECFS) convened an expert panel of specialists to develop consensus recommendations for the screening, investigation, diagnosis and management of NTM pulmonary disease in individuals with CF. Nineteen experts were invited to participate in the recommendation development process. Population, Intervention, Comparison, Outcome (PICO) methodology and systematic literature reviews were employed to inform draft recommendations. An anonymous voting process was used by the committee to reach consensus. All committee members were asked to rate each statement on a scale of: 0, completely disagree, to 9, completely agree; with 80% or more of scores between 7 and 9 being considered ‘good’ agreement. Additionally, the committee solicited feedback from the CF communities in the USA and Europe and considered the feedback in the development of the final recommendation statements. Three rounds of voting were conducted to achieve 80% consensus for each recommendation statement. Through this process, we have generated a series of pragmatic, evidence-based recommendations for the screening, investigation, diagnosis and treatment of NTM infection in individuals with CF as an initial step in optimising management for this challenging condition.

Nontuberculous Mycobacterial Infections in Cystic Fibrosis

Nontuberculous mycobacteria (NTM) are important emerging cystic fibrosis (CF) pathogens, with estimates of prevalence ranging from 6% to 13%. Diagnosis of NTM disease in patients with CF is challenging, as the infection may remain indolent in some, without evidence of clinical consequence, whereas other patients suffer significant morbidity and mortality. Treatment requires prolonged periods of multiple drugs and varies depending on NTM species, resistance pattern, and extent of disease. The development of a disease-specific approach to the diagnosis and treatment of NTM infection in CF patients is a research priority, as a lifelong strategy is needed for this high-risk population.

Rapid detection and immune characterization of Mycobacterium abscessus infection in cystic fibrosis patients

Cystic fibrosis patients are highly susceptible to infections with non-tuberculous mycobacteria. Especially Mycobacterium abscessus infections are common but reliable diagnosis is hampered by non-specific clinical symptoms and insensitive mycobacterial culture. In the present study we established novel methods for rapid detection and immune characterization of Mycobacterium abscessus infection in cystic fibrosis patients. We performed Mycobacterium abscessus specific DNA-strip- and quantitative PCR-based analyses of non-cultured sputum samples to detect and characterize Mycobacterium abscessus infections. Concomitantly in vitro T-cell reactivation with purified protein derivatives (PPDs) from different mycobacterial species was used to determine Mycobacterium abscessus specific T-cell cytokine expression of infected cystic fibrosis patients. Four of 35 cystic fibrosis patients (11.4%) were Mycobacterium abscessus culture positive and showed concordant DNA-strip-test results. Quantitative PCR revealed marked differences of mycobacterial burden between cystic fibrosis patients and during disease course. Tandem-repeat analysis classified distinct Mycobacterium abscessus strains of infected cystic fibrosis patients and excluded patient-to-patient transmission. Mycobacterium abscessus specific T-cells were detected in the blood of cystic fibrosis patients with confirmed chronic infection and a subgroup of patients without evidence of Mycobacterium abscessus infection. Comparison of cytokine expression and phenotypic markers revealed increased proportions of CD40L positive T-cells that lack Interleukin-2 expression as a marker for chronic Mycobacterium abscessus infections in cystic fibrosis patients. Direct sputum examination enabled rapid diagnosis and quantification of Mycobacterium abscessus in cystic fibrosis patients. T-cell in vitro reactivation and cytokine expression analyses may contribute to diagnosis of chronic Mycobacterium abscessus infection.

Microbiological diagnosis of nontuberculous mycobacterial pulmonary disease

Pulmonary disease is by far the most frequent disease caused by nontuberculous mycobacteria (NTM). To diagnose NTM pulmonary disease (NTM-PD), patients should have symptoms and radiologic signs suggestive of NTM-PD, and cultures of multiple respiratory tract samples must grow the same NTM species. Thus, the microbiological laboratory has a central role in the diagnosis of NTM-PD. This review summarizes currently available data on techniques involved in the microbiological diagnosis of NTM-PD, and aims to provide a framework for optimal microbiological diagnosis.

Non-tuberculous mycobacterial infections of veterinary relevance

Mycobacteria play an important role in human and animal health fields. We here examine the place of non tuberculous mycobacteria (NTM) infections in the veterinary context. Relevant aspects of a reference laboratory experience and a literature review are presented in this article. Importance is given both to productivity and to economic losses due to misdiagnosis with bovine tuberculosis and paratuberculosis. The impact NTM may have is relative to geographical location, ecology, husbandry, extent of surveillance programs and bovine tuberculosis and paratuberculosis prevalence. The role of the most relevant NTM in animal disease is summarized with a special focus on Mycobacterium avium subsp. paratuberculosis, given its role as causative agent of paratuberculosis, a disease with huge economic consequences for ruminant livestock.

Prevalence and drug resistance of mycobacteria in Turkish cystic fibrosis patients

BACKGROUND

Isolation of mycobacteria in cystic fibrosis (CF) patients is increasingly being reported. Because of having long term antimicrobial treatment, CF patients are at risk of pulmonary infection with especially resistant nontuberculous mycobacteria (NTM) strains. The aim of the present study is to determine the prevalence of mycobacterium spp. and antimicrobial susceptibility in Turkish CF patients.

METHODS

During a 5.5 year study period, 376 sputa from 130 CF patients were analyzed. Antimycobacterial susceptibility testing was performed by the Bactec 460 TB System and the E test method.

RESULTS

Totaly 28 (7.44%) Mycobacterium spp. were isolated from eight (6.15%) CF patients. Five isolates (17.9%) were identified as Mycobacterium tuberculosis complex (MTBC), 14 (50%) as Mycobacterium abscessus and nine (32.1%) as Mycobacterium lentiflavum. All MTBC isolates were found to be susceptible to streptomycin, isoniazid, rifampicin, and ethambutol. Resistance to some antibiotics was detected in some NTM strains. These are the first data about the prevalence of mycobacteria in CF patients from Turkey.

CONCLUSIONS

In pediatric CF patients, specific mycobacterial analysis of sputum specimens and susceptibility testing should be performed for allowing early detection, identification and the possibility of eradication of these bacteria.

Culture-based diagnostic microbiology in cystic fibrosis: can we simplify the complexity?

Cystic fibrosis (CF) diagnostic microbiology has evolved from a focus on Staphylococcus aureus as primary pathogen to identification of the contribution of Pseudomonas aeruginosa and other non-fermenting gram negatives; studies of the lung microbiome have added new complexity. This review summarizes state-of-the art culture methods and makes recommendations for addition of non-culture based methods in the diagnostic laboratory. Plating on selective media is recommended, with organism identification by matrix assisted laser desorption-time of flight mass spectroscopy and real-time polymerase chain reaction (PCR) supplanting both biochemical identification and other less accurate and more time-consuming molecular methods. Conventional antibiotic susceptibility testing, possibly at less frequent intervals, remains the standard but more CF-relevant methods may arise in the future. There is a role for direct identification of organisms in clinical samples using quantitative real-time PCR, next generation sequencing, and metagenomic studies for the re-examination of samples that do not yield traditional CF pathogens.

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.

Detection of rapidly growing mycobacteria in routine cultures of samples from patients with cystic fibrosis

Rapidly growing mycobacteria (RGM) are respiratory pathogens in patients with cystic fibrosis (CF), but detection generally requires specialized cultures for acid-fast bacilli (AFB; AFB cultures). We determined that RGM could be recovered from routine cultures of samples from patients with CF by extending incubation of the Burkholderia cepacia selective agar (BCSA) from 5 to 14 days. To explore the impact of this modification, we compared results from routine and AFB cultures of samples from CF patients for 2 years before (4,212 samples by routine culture, 1,810 samples by AFB culture, 670 patients) and 2 years after (4,720 samples by routine culture, 2,179 samples by AFB culture, 695 patients) the change. Clinical relevance was assessed with samples from a subgroup of 340 patients followed regularly throughout both periods. Extending incubation of BCSA enhanced RGM recovery from routine cultures (0.7% before, 2.8% after; P < 0.001); recovery from AFB cultures was unchanged (5.5% before, 5.7% after). Estimates of RGM detection sensitivity by culture or patient-based methods ranged from ∼65 to 75% for routine cultures (nonsignificantly lower than the ∼80 to 85% for AFB cultures) and were adversely affected by coculture with mold or nonpseudomonal, nonfermenting Gram-negative rods. In the after period, 16 CF patients met the criteria for RGM infection by routine culture, including 4 who did not meet the criteria for RGM infection by AFB culture. We conclude that a simple methodological change enhanced recovery of RGM from routine cultures. The modified culture method could be utilized to improve screening for RGM in CF patients or as a simpler method to follow patients with known RGM infection. However, this method should be used cautiously in patients with certain coinfections.

Chronic Mycobacterium abscessus infection and lung function decline in cystic fibrosis

BACKGROUND

Although nontuberculous mycobacteria (NTM) are recognized pathogens in cystic fibrosis (CF), associations with clinical outcomes remain unclear.

METHODS

Microbiological data was obtained from 1216 CF patients over 8years (481+/-55patients/year). Relationships to clinical outcomes were examined in the subset (n=271, 203+/-23 patients/year) with longitudinal data.

RESULTS

Five hundred thirty-six of 4862 (11%) acid-fast bacilli (AFB) cultures grew NTM, with Mycobacterium abscessus (n=298, 55.6%) and Mycobacterium avium complex (n=190, 35.4%) most common. Associated bacterial cultures grew Stenotrophomonas or Aspergillus species more often when NTM were isolated (18.2% vs. 8.4% and 13.9% vs. 7.2%, respectively, p<0.01). After controlling for confounders, patients with chronic M. abscessus infection had greater rates of lung function decline than those with no NTM infection (-2.52 vs. -1.64% predicted FEV(1)/year, p<0.05).

CONCLUSIONS

NTM infection is common in CF and associated with particular pathogens. Chronic M. abscessus infection is associated with increased lung function decline.

Molecular epidemiology of Mycobacterium abscessus, with focus on cystic fibrosis

Mycobacterium abscessus has been isolated increasingly often from the respiratory tracts of cystic fibrosis (CF) patients. It is not known whether these organisms are transmitted from person to person or acquired from environmental sources. Here, colony morphology and pulsed-field gel electrophoresis (PFGE) pattern were examined for 71 isolates of M. abscessus derived from 14 CF patients, three non-CF patients with chronic respiratory M. abscessus infection or colonization, one patient with mastoiditis, and four patients with infected wounds, as well as for six isolates identified as environmental contaminants in various clinical specimens. Contaminants and wound isolates mainly exhibited smooth colony morphology, while a rough colony phenotype was significantly associated with chronic airway colonization (P=0.014). Rough strains may exhibit increased airway-colonizing capacity, the cause of which remains to be determined. Examination by PFGE of consecutive isolates from the same patient showed that they all represented a single strain, even in cases where both smooth and rough isolates were present. When PFGE patterns were compared, it was shown that 24 patients had unique strains, while four patients harbored strains indistinguishable by PFGE. Two of these were siblings with CF. The other two patients, one of whom had CF, had not had contact with each other or with the siblings. Our results show that most patients colonized by M. abscessus in the airways have unique strains, indicating that these strains derive from the environment and that patient-to-patient transmission rarely occurs.

Value of the chlorhexidine decontamination method for recovery of nontuberculous mycobacteria from sputum samples of patients with cystic fibrosis

The chlorhexidine method was compared to the N-acetyl-l-cysteine-NaOH-oxalic acid decontamination method currently recommended for the recovery of nontuberculous mycobacteria (NTM) from patients with cystic fibrosis. Sputum samples (n = 827) treated with chlorhexidine yielded twice as many NTM-positive cultures as those treated by the reference method (54 [6.50%] versus 27 [3.25%]; P < 0.0001) despite a higher contamination rate (20% versus 14.2%; P = 0.0017).

Non-tuberculous mycobacteria in end stage cystic fibrosis: implications for lung transplantation

BACKGROUND

WC and NS contributed equally. Non-tuberculous mycobacteria (NTM) frequently colonise patients with end stage cystic fibrosis (CF), but its impact on the course of the disease following lung transplantation is unknown.

METHODS

Lung transplant recipients with CF who underwent lung transplantation at our institution between January 1990 and May 2003 (n=146) and CF patients awaiting lung transplantation in May 2003 (n=31) were studied retrospectively.

RESULTS

The prevalence rate of NTM isolated from respiratory cultures in patients with end stage CF referred for lung transplantation was 19.7%, compared with a prevalence rate of 13.7% for NTM isolates in CF lung transplant recipients. The overall prevalence of invasive NTM disease after lung transplantation was low (3.4%) and was predicted most strongly by pre-transplant NTM isolation (p=0.001, Fisher's exact test, odds ratio (OR) 6.13, 95% CI 3.2 to 11.4). This association was restricted to Mycobacterium abscessus (p = 0.005, Fisher's exact test, OR 7.45, 95% CI 2.9 to 16.9). While NTM disease caused significant morbidity in a small number of patients after transplantation, it was successfully treated and did not influence the post-transplant course of the disease.

CONCLUSION

The isolation of NTM before transplantation in CF patients should not be an exclusion criterion for lung transplantation, but it may alert the clinician to patients at risk of recurrence following transplantation.

Age-related prevalence and distribution of nontuberculous mycobacterial species among patients with cystic fibrosis

We studied the prevalence and species distribution of nontuberculous mycobacteria (NTM) in relation to age in 385 patients with cystic fibrosis (CF) (mean age +/- standard deviation [range], 12.0 +/- 6.1 [1 to 24] years; sex ratio, 0.53) attending three Parisian centers. The overall prevalence of NTM in sputum was 8.1% (31 out of 385). The following NTM were isolated (n = 33): Mycobacterium abscessus (n = 13, 39.4%), Mycobacterium avium complex (MAC) (n = 7, 21.2%), Mycobacterium gordonae (n = 6, 18.2%), and other (n = 7, 21.2%). Sixteen patients met the American Thoracic Society microbiological criteria for NTM infection, including 11 patients positive for M. abscessus, 4 for MAC, and 1 for MAC and Mycobacterium kansasii. The overall prevalence of NTM was significantly lower in patients under 15 years old than for patients equal to or more than 15 years old (4.8 versus 14.9%, respectively; P = 0.001). M. abscessus was isolated at all ages, while MAC was not recovered before 15 years (prevalence of 0.0 and 5.2% in patients aged 1 to 14 and 15 to 24, respectively; P = 0.001).

Mycobactéries atypiques et mucoviscidose

Patients with cystic fibrosis are particularly at risk of infection with non-tuberculous mycobacteria (NTM). Prevalence of these infections increases with age to around 15 %. The main species involved are M. abscessus and M. avium, the latter not found in children under 15. Diagnosis relies on clinical, radiological and above all bacteriological criteria defined by the ATS. Identification of the causal species of NTM is essential and requires genetic techniques, some of which are currently evaluated. Treatment depends on the mycobacterial species. For M. avium, combined therapy with rifampicin, clarithromycin and ethambutol must be extended 12 months after negativation. M. abscessus infection is particularly resistant to therapy. Usual treatment is a one month course of intravenous imipenem or cefoxitin plus amikacin followed by oral clarithromycin plus ethambutol for at least 12 months after negativation. In case of local lesions, surgery is an option.

Mycobacterium abscessus and other nontuberculous mycobacteria: evolving respiratory pathogens in cystic fibrosis: a case report and review

Cystic fibrosis (CF) is a risk factor for the development of nontuberculous mycobacteria (NTM) infection. Prevalence of these organisms varies from center to center with the predominance of affected patients being in the adult population. The difficulty in diagnosing NTM infection in CF involves the overlap between signs and symptoms of underlying CF lung disease with its variable pathogens and the signs and symptoms attributable to pulmonary disease caused by NTM. Bacterial overgrowth, especially with Pseudomonas aeruginosa, is problematic, leading to the difficulty in recovering mycobacteria from sputum. There is varying opinion whether the presence of NTM in pulmonary secretions of patients with CF indicates infection or colonization from an environmental organism. This report describes a 14-year-old asymptomatic female patient with CF with minimal bronchiectasis on high-resolution computed tomography scan of the chest who clinically deteriorated over the next 29 months after acquiring Mycobacterium abscessus to the point of being listed for lung transplantation. As more is discovered about NTM, the pathogenicity and virulence of these organisms should be considered in the setting of CF and treated.

Measurement of Immunoglobulin G against Mycobacterial Antigen A60 in Patients with Cystic Fibrosis and Lung Infection Due to Mycobacterium abscessus

BACKGROUND

The diagnosis and prognosis of lung infections due to the emerging nontuberculous mycobacterium (NTM) Mycobacterium abscessus are difficult to establish in children with cystic fibrosis.

METHODS

We evaluated the usefulness of an enzyme-linked immunosorbent assay for detecting serum IgG antibodies against the ubiquitous mycobacterial antigen A60.

RESULTS

A total of 186 patients with cystic fibrosis (mean age+/-SD, 12.0+/-5.0 years) were studied, including 15 M. abscessus-positive patients who fulfilled American Thoracic Society (ATS) criteria for NTM infection (M. abscessus-infected patients), 7 M. abscessus-positive patients who did not fulfill ATS criteria, 20 patients positive for various other NTM who did not fulfill ATS criteria, and 144 NTM-negative control patients; mean IgG titers (+/-SD) for these 4 groups were 718+/-342 U, 193+/-113 U, 129+/-49 U, and 121+/-53 U, respectively (M. abscessus-infected patients vs. each of the other groups, P<.005). The A60 IgG test was both sensitive (approximately 87%) and specific (approximately 95%) if adapted cutoff values were used (150 U and 250 U for patients aged <or=10 years and patients aged >10 years, respectively) and correlated well with results of acid-fast bacilli smears.

CONCLUSION

Measurement of anti-A60 IgG may be useful for both the diagnosis and assessment of activity of M. abscessus lung infection in persons with cystic fibrosis.

The natural history of nontuberculous mycobacteria in patients with cystic fibrosis

With the increasing lifespan of persons with cystic fibrosis (CF), the emergence of a variety of previously seldom seen pathogens, including the nontuberculous mycobacteria (NTM), has been seen. Determining the impact of these indolent organisms on the natural history of cystic fibrosis lung disease has been difficult. We initiated a two-stage study in 1993 to assess the prevalence and clinical impact of these organisms among persons with CF in US CF Centers. These organisms were frequently recovered from older patients with relatively mild disease. While over the short, 15-month course of follow-up no significant differences in the rate of decline of lung function attributable to NTM were seen, concerning changes and progression of high-resolution computed tomography findings were seen in patients from whom these organisms were repeatedly recovered.

Mycobacterium abscessus and children with cystic fibrosis

We prospectively studied 298 patients with cystic fibrosis (mean age 11.3 years; range 2 months to 32 years; sex ratio, 0.47) for nontuberculous mycobacteria in respiratory samples from January 1, 1996, to December 31, 1999. Mycobacterium abscessus was by far the most prevalent nontuberculous mycobacterium: 15 patients (6 male, 9 female; mean age 11.9 years; range 2.5–22 years) had at least one positive sample for this microorganism (versus 6 patients positive for M. avium complex), including 10 with >3 positive samples (versus 3 patients for M. avium complex). The M. abscessus isolates from 14 patients were typed by pulsed-field gel electrophoresis: each of the 14 patients harbored a unique strain, ruling out a common environmental reservoir or person-to-person transmission. Water samples collected in the cystic fibrosis center were negative for M. abscessus. This major mycobacterial pathogen in children and teenagers with cystic fibrosis does not appear to be acquired nosocomially.

Infection control recommendations for patients with cystic fibrosis: microbiology, important pathogens, and infection control practices to prevent patient-to-patient transmission

Infection Control Recommendations for Patients With Cystic Fibrosis: Microbiology, Important Pathogens, and Infection Control Practices to Prevent Patient-to-Patient Transmissionupdates, expands, and replaces the consensus statement,Microbiology and Infectious Disease in Cystic Fibrosispublished in 1994. This consensus document presents background data and evidence-based recommendations for practices that are intended to decrease the risk of transmission of respiratory pathogens among CF patients from contaminated respiratory therapy equipment or the contaminated environment and thereby reduce the burden of respiratory illness. Included are recommendations applicable in the acute care hospital, ambulatory, home care, and selected non-healthcare settings. The target audience includes all healthcare workers who provide care to CF patients. Antimicrobial management is beyond the scope of this document.

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.

Nontuberculous mycobacteria. I: multicenter prevalence study in cystic fibrosis

Nontuberculous mycobacteria (NTM) are potential respiratory pathogens in cystic fibrosis (CF). To assess the species-specific prevalence and risk factors for acquisition, we conducted a prospective, cross-sectional study of the prevalence of NTM and clinical features of patients at 21 U.S. centers. Almost 10% of patients with CF who were 10 years or older were included (n = 986). The overall prevalence of NTM in sputum was 13.0% (range by center, 7-24%). Mycobacterium avium complex (72%) and Mycobacterium abscessus (16%) were the most common species. When compared with patients with CF without NTM, culture-positive subjects were older (26 vs. 22 years, p < 0.001), had a higher FEV1 (60 vs. 54%, p < 0.01), higher frequency of Staphylococcus aureus (43 vs. 31%, p < 0.01), and lower frequency of Pseudomonas aeruginosa (71 vs. 82%, p < 0.01). Molecular typing revealed that almost all patients within each center had unique NTM strains. In summary, NTM are common in patients with CF, but neither person-to-person nor nosocomial acquisition explained the high prevalence. Older age was the most significant predictor for isolation of NTM. The clinical significance of NTM in CF is incompletely defined, but patients with these organisms should be monitored with repeat cultures.

Laboratory diagnosis of nontuberculous mycobacteria

In conclusion, it is important to realize that there is no "stand alone" assay for the identification of NTM. Many new species may not be recognized in all assays. Newer molecular tests are more accurate for identification than phenotypic tests and have significantly improved turnaround time. Clinical significance of an isolate should be determined, however, before committing resources for the identification of a mycobacterial isolate to the species level. In addition, there are significant differences in the range and quality of services provided by different laboratories. Today, techniques and equipment are increasingly complex and costly, making it more difficult to upgrade every local laboratory to perform these assays. But because specimen delivery and communication of results can be rapidly and easily achieved, utilization of reference laboratories for rarely performed sophisticated tests is a more practical approach.

Nontuberculous mycobacteria in the setting of cystic fibrosis

Nontuberculous mycobacterial pulmonary infections are increasingly recognized in patients with CF. This may reflect the increasing longevity of this population with increased environmental exposure time, a higher clinical index of suspicion, and/or some as yet unidentified predisposing factor(s). The most common species of NTM in CF is MAC, followed by M abscessus. We recommend that adult patients with CF be screened for the presence of nontuberculous mycobacteria in pulmonary secretions on a regular basis, and that consideration be given to this diagnosis if a patient has an escalating pattern of exacerbations or admissions. Positive cultures are likely to indicate disease if they are multiple or if a patient has clinical evidence of pulmonary disease exacerbation (increased cough, increased purulence of secretions, systemic manifestations such as fever, weight loss) that is not responding to conventional antibiotic therapy. Cystic fibrosis patients who do not respond to treatment for the usual organisms should be carefully re-evaluated for the presence of NTM and treated with a macrolide-containing multidrug regimen directed against the identified NTM if diagnostic criteria are met. Novel treatments with cytokines and intermittent dosing of antibiotics are currently under investigation in non-CF populations and may have applicability to CF in the future.

Nontuberculous mycobacteria in cystic fibrosis

The incidence of NTM pulmonary infections increasingly is recognized in patients with CF. This may reflect the increasing longevity of this population with increased environmental exposure time, a high index of suspicion, and/or some as of yet unidentified predisposing factor(s). The most common species of NTM in CF is MAC, followed by M. abscessus. The authors recommend that adult patients with CF be screened for the presence of NTM pulmonary secretions on a regular basis. Positive cultures are likely to indicate disease if they are multiple or if a patient has clinical evidence of pulmonary disease exacerbation (increased cough, increased purulence of secretions, or systemic manifestations such as fever and weight loss) that is not responding to conventional antibiotic therapy. CF patients who do not respond to treatment for the usual organisms should be re-evaluated for the presence of NTM and treated with a macrolide-containing regimen directed against the identified NTM if diagnostic criteria are met. Novel treatments with cytokines and intermittent dosing of antibiotics are currently under investigation.

Fatal pulmonary infection due to multidrug-resistant Mycobacterium abscessus in a patient with cystic fibrosis

We report a case of fatal pulmonary infection caused by Mycobacterium abscessus in a young patient with cystic fibrosis, who underwent bipulmonary transplantation after a 1-year history of severe lung disease. Fifteen days after surgery he developed septic fever with progressive deterioration in lung function. M. abscessus, initially isolated from a pleural fluid specimen, was then recovered from repeated blood samples, suggesting a disseminated nature of the mycobacterial disease. Drug susceptibility testing assay, performed on two sequential isolates of the microorganism, showed a pattern of multidrug resistance. Despite aggressive therapy with several antimycobacterial drugs, including clarithromycin, the infection persisted, and the patient died.

Recovery of mycobacteria from patients with cystic fibrosis

Despite decontamination, overgrowth by pseudomonads renders cultural isolation of mycobacteria from respiratory specimens of patients with cystic fibrosis (CF) difficult or impossible. We performed a prospective study by comparing levels of reduction of overgrowth and recovery of mycobacteria using either pretreatment with N-acetyl-L-cysteine (NALC)-NaOH alone or pretreatment with NALC-NaOH and then with oxalic acid. From 406 specimens of 148 CF patients, 11 specimens were positive for mycobacteria, 5 of which grew mycobacteria after decontamination by either procedure. Three specimens grew mycobacteria only after decontamination with NALC-NaOH, whereas three specimens grew mycobacteria only after treatment with NALC-NaOH followed by oxalic acid but were overgrown after decontamination with NALC-NaOH. Thus, inactivation of mycobacteria by the more aggressive oxalic acid treatment offsets its beneficial effect of reducing the proportion of cultures overgrown with microorganisms other than mycobacteria.