Mycobacterium abscessus empyema in a lung transplant recipient

Nontuberculous mycobacteria infections of the pleura: A systematic review

BACKGROUND

Nontuberculous mycobacterial (NTM) pleuritis is an uncommon manifestation of NTM infection. Case reports and small case series have shown a variable clinical course and high mortality rates.

OBJECTIVE

To describe patients' characteristics, clinical presentation and outcomes of NTM pleural infections.

METHODS

A systematic review of cases of NTM pleural infections published in PubMed-indexed journals from 1980 to 2021.

RESULTS

A total of 206 cases of NTM pleural infections were found and analyzed. Fifty-eight percent of cases were males. The mean age was 57.5 yrs (range 9-87 yrs). Forty-three percent of patients were immunosuppressed, and 43% had a chronic lung disease; thirty-two percent had neither risk factor. In addition to the pleural infection, 67% of cases had a concurrent pulmonary NTM infection, and in 18 cases there was another extrapulmonary site of NTM infection. In 29% of cases the pleural infection was the sole manifestation of NTM disease. The most common isolated mycobacterium was Mycobacterium avium complex (65%). Fifty-three percent and 26% of patients required pleural effusion drainage and a surgical intervention, respectively, to treat the infection, in addition to anti-NTM chemotherapy. Forty percent of patients developed pneumothorax, 16% suffered from empyema, and 16.5% had broncho-pleural fistula. The reported mortality rate was 24%.

CONCLUSION

NTM pleural infections may arise in immunocompetent and immunosuppressed patients, with or without chronic lung disease or concurrent NTM pulmonary infection. These infections carry a poor prognosis and a high risk of complications requiring surgical interventions in addition to anti-NTM chemotherapy.

Bacterial infections in lung transplantation

Lung transplantation has lower survival rates compared to other than other solid organ transplants (SOT) due to higher rates of infection and rejection-related complications, and bacterial infections (BI) are the most frequent infectious complications. Excess morbidity and mortality are not only a direct consequence of these BI, but so are subsequent loss of allograft tolerance, rejection, and chronic lung allograft dysfunction due to bronchiolitis obliterans syndrome (BOS). A wide variety of pathogens can cause infections in lung transplant recipients (LTRs), including a number of nosocomial pathogens and other multidrug-resistant (MDR) pathogens. Although pneumonia and intrathoracic infections predominate, LTRs are at risk of a number of types of infections. Risk factors include altered anatomy and function of airways, impaired immunity, the microbial flora of the donor and recipient, underlying medical conditions, and genetic factors. Further work on immune monitoring has the potential to improve outcomes. The infecting agents can be derived from the donor lung, pre-existing recipient flora, or acquired from the environment over time. Certain infections may preclude lung transplantation, but this varies from center to center, and more recent studies suggest fewer patients should be disqualified. New molecular methods allow microbiome studies of the lung, gut, and other sites that may further our knowledge of how airway colonization can result in infection and allograft loss. Surveillance, early diagnosis, and aggressive antimicrobial therapy of BI is critical in LTRs. Antibiotic resistance is a major barrier to successful management of these infections. The availability of new agents for MDR Gram-negatives may improve outcomes. Other new therapies, such as bacteriophage therapy, show promise for the future. Finally, it is important to prevent infections through peri-transplant prophylaxis, vaccination, and infection control measures.

Life-threatening Mycobacterium intracellulare pleuritis in an immunocompetent host: Case reports

RATIONALE

Nontuberculous mycobacteria (NTM)-associated pleuritis is a very rare disease. Here, we describe 2 cases of life-threatening Mycobacterium intracellulare-associated pleuritis in immunocompetent hosts.

PATIENT CONCERNS

A 78-year-old man with sudden onset-onset dyspnea (case 1) and an 80-year-old man with cough, sputum and fever (case 2) presented to our emergency room.

DIAGNOSES

Both the patients were diagnosed with Mycobacterium intracellulare-associated pleuritis.

INTERVENTION

In case 1, the patient underwent intubation with mechanical ventilation due to hypoxemic respiratory failure. Daily azithromycin, rifampin and ethambutol, and intravenous amikacin 3 times a week was administered. In case 2, the patient received daily azithromycin, rifampin and ethambutol, and intravenous amikacin 3 times a week.

OUTCOMES

In case 1, after receiving NTM treatment for 14 months, NTM-associated pleuritis was cured, with radiologic improvement. In case 2, however, bronchopleural fistula was developed. Despite tube drainage, air leak continued. The patient refused surgical management and eventually died of respiratory failure.

LESSONS

Pleural effusion arising from NTM lung disease located in the subpleural area should be considered a possible cause of NTM-associated pleuritis. Drainage and a multidrug regimen are required to treat NTM, and surgical treatment should be considered when complications occur.

Outcomes of nontuberculous mycobacteria isolation among lung transplant recipients: A matched case-control with retrospective cohort study

DISCLAIMER

In an effort to expedite the publication of articles , AJHP is posting manuscripts online as soon as possible after acceptance. Accepted manuscripts have been peer-reviewed and copyedited, but are posted online before technical formatting and author proofing. These manuscripts are not the final version of record and will be replaced with the final article (formatted per AJHP style and proofed by the authors) at a later time.

PURPOSE

Lung transplant recipients are at increased risk for acquiring nontuberculous mycobacteria (NTM), but the clinical significance of NTM isolation, particularly among patients not meeting guideline-endorsed diagnostic criteria for NTM pulmonary disease, is unclear.

METHODS

A case-control study of lung transplant recipients with culture-positive NTM infections treated at a large transplant center during a 7-year period (2013-2019) was performed.

RESULTS

Twenty-nine cases were matched 1:2 to non-NTM controls. The median time to NTM isolation was 10.7 months post transplant. Only 34.5% of all cases, and half of treated cases, met diagnostic criteria for NTM pulmonary infection. All-cause mortality at 12 months was numerically higher among NTM cases versus controls (20.7% vs 8.6%, P = 0.169); however, no deaths were attributed to NTM. No increase in the 12-month rate of acute rejection was observed (27.6% vs 36.2%, P = 0.477). Recent augmented immunosuppression was associated with increased odds of NTM isolation, while azithromycin prophylaxis was associated with reduced odds of isolation and was not associated with macrolide resistance. Both adverse events and actual or potential drug-drug interactions occurred in more than 90% of treated cases; these events included ocular toxicity, hearing loss, and supratherapeutic calcineurin inhibitor concentrations. Eight of the 14 treated cases (57.1%) required early antibiotic discontinuation due to adverse events or drug-drug interactions.

CONCLUSION

Among lung transplant recipients, most patients with NTM isolation did not meet guideline criteria for infection and had outcomes similar to non‒NTM-infected patients, which may reflect transient lung colonization by NTM rather than true disease. As adverse events are common with NTM therapy, limiting unnecessary antibiotic treatment represents an area for future antimicrobial stewardship efforts.

Mycobacterium abscessus subsp. abscessus empyema complicated with subcutaneous abscess

There have been no case reports of thoracic subcutaneous abscess after surgery for Mycobacterium abscessus complex associated empyema. We herein report a case of Mycobacterium abscessus subsp. abscessus (M. abscessus subsp. abscessus) induced subcutaneous abscesses following surgical treatment for concurrent M. abscessus subsp. abscessus -associated empyema and pneumothorax. A 75-year-old woman had M. abscessus subsp. abscessus -associated empyema and pneumothorax. She underwent surgical treatment of decortication and fistulectomy and suffered from M. abscessus subsp. abscessus -associated subcutaneous abscesses after thoracentesis/drainage. A multidisciplinary approach combined with surgical care, thermal therapy, and multidrug chemotherapy contributed to a successful result. An early multidisciplinary approach is believed to be important in cases of M. abscessus subsp. abscessus -associated empyema and subcutaneous abscess.

Nontuberculous mycobacterial infection after lung transplantation: a report of four cases

Background

Nontuberculous mycobacterium (NTM) infection in a patient in an immunosuppressed state caused by increased use of immunosuppressive or biological agents is a serious clinical problem. Mycobacterium avium complex is the most common involved pathogen, followed by Mycobacterium abscessus (MABSC), while Mycobacterium kansasii is not a major concern. The rate of infection rate in lung transplant recipients is reported to range from 1.5–22.4%.

Case presentation

We report here four cases of NTM pulmonary infection and disease among 63 patients who underwent lung or heart-lung transplantation at our hospital. Those four occurred following living-donor transplantation in two patients, one with pulmonary arterial hypertension and one with bronchiectasia, and deceased donor lung transplantation in two patients, lymphangioleiomyomatosis and interstitial pneumonia, respectively. NTM was not detected in any of the patients prior to transplantation. The involved pathogens were Mycobacterium gordonae in one, MAC in one, and MABSC in two of these patients, which were isolated from broncho-alveolar lavage (BAL) in two and sputum in two. The one case of MAC and two of MABSC were symptomatic with consolidation shown in chest CT images indicating possible pneumonia, while the one with M. gordonae had no symptoms and was detected by surveillance BAL. Onset time from detection of NTM was greater than 3 years in the three with MABSC and M. gordonae and less than 3 years in the one with MAC. Each patient required a decrease in immunosuppressive agents according to their condition, while antibiotics therapy was performed in the three who were symptomatic. Sputum culture findings became negative after several months and were maintained thereafter in all.

Conclusion

An NTM infection leading to pulmonary disease can occur at any time following lung transplantation. Treatment should be considered depending on the involved pathogens, individual status, and disease severity.

Infections in Heart, Lung, and Heart-Lung Transplantation

Half a century has passed since the first orthotopic heart transplant took place. Surgical innovations allowed for heart, lung, and heart-lung transplantation to save lives of patients with incurable chronic cardiopulmonary conditions. The complexity of the surgical interventions, chronic host health conditions, and antirejection immunosuppressive medications makes infectious complications common. Infections have remained one of the main barriers for successful transplantation and a source of significant morbidity and mortality. Recognition of infections and its management in this setting require outstanding clinical skills since transplant recipients may not exhibit classic signs or symptoms of disease, and laboratory work has some pitfalls. The prevention, identification, and management of infectious diseases complications in this population are a priority to undertake to improve the medical outcomes of transplantation. Herein, we reviewed the historical aspects, epidemiology, and prophylaxis of infections in heart, lung, and heart-lung transplantation. We also discuss the most prevalent organisms affecting the host and the organ systems involved.

Pleurisy Caused by Mycobacterium abscessus in a Young Patient with Dermatomyositis: A Case Report and Brief Review of the Literature

M. abscessus is a rapidly growing mycobacteria (RGM) and is the most common cause of pulmonary RGM infection. M. abscessus pleurisy is extremely rare. We herein report the case of a young patient with M. abscessus pleurisy without any lung lesions. A laboratory analysis of the pleural effusion revealed lymphocyte predominance and increased adenosine deaminase, similar to the findings observed in tuberculous pleurisy. The patient was initially treated for tuberculous pleurisy, which resulted in the partial improvement of the patient's symptoms and pleural effusion. M. abscessus pleurisy should be considered, especially in immunocompromised individuals, even in the absence of pulmonary involvement.

Mycobacterium abscessus disease in lung transplant recipients: Diagnosis and management

Mycobacterium abscessus complex (MAbsC) disease in lung transplant recipients is increasingly being recognized as an important cause of graft function decline and suboptimal outcomes. Lung transplant recipients appear to be at the highest risk of MAbsC among solid organ transplant recipients, as they have more intense immunosuppression, and the organisms preferentially inhabit the lungs. MAbsC is the most resistant species of rapidly growing mycobacteria and difficult to treat, causing considerable mortality and morbidity in immunocompetent and immunosuppressed patients. Herein we describe the risk factors, epidemiology, clinical features, diagnostics, and treatment strategies of MAbsC in lung transplant candidates and recipients.

Pulmonary tuberculous and tuberculous pericardial tamponade post lung transplant

Pulmonary tuberculosis (TB) associated with tuberculous pericarditis after lung transplantation is a very rare entity. Here we report a unique case of cardiac tamponade due to tuberculous pericarditis, in a patient 4 months after single right lung transplantation, the patient underwent a subxyphoid pericardial window. The pericardial effusion analysis showed exudate effusion with high level of lymphocyte concentration. Both patient and donor didn't have history of TB or TB Exposure.

Tuberculous Empyema Post Bilateral Lung Transplant

Tuberculous empyema in lung transplantation recipients is a rare entity, with only a handful of cases reported in the English-language literature. We are reporting a case of tuberculous empyema 3 months after uncomplicated bilateral lung transplantation. The recipient underwent video-assisted thoracic surgery for diagnosis and decortication. Both the recipient and donor lacked a history of tuberculosis or tuberculosis exposure.

Analysis of pulmonary non-tuberculous mycobacterial infections after lung transplantation

PURPOSE

Non-tuberculous mycobacteria (NTM) are important pathogens in lung transplant recipients. This study describes the spectrum of NTM respiratory tract infections and examines the association of NTM infections with lung transplant complications.

METHODS

Data from 208 recipients transplanted from November 1990 to November 2005 were analyzed. Follow-up data were available to November 2010. Lung infection was defined by bronchoalveolar lavage, sputum, or blood cultures in the appropriate clinical setting. All identified NTM respiratory tract infections were tabulated. The cohort of patients with NTM lung infections (NTM+) were compared to the cohort without infection (NTM-). Univariate and multivariate analysis was performed to determine characteristics associated with NTM infection. Survival analyses for overall survival and development of bronchiolitis obliterans syndrome (BOS) were also performed.

RESULTS

In total, 52 isolates of NTM lung infection were identified in 30 patients. The isolates included Mycobacterium abscessus (46%), Mycobacterium avium complex (MAC) (36%), Mycobacterium gordonae (9%), Mycobacterium chelonae (7%), and Mycobacterium fortuitum (2%), with multiple NTM isolates seen on 3 different occasions. The overall incidence was 14%, whereas cumulative incidences at 1, 3, and 5 years after lung transplantation were 11%, 15%, and 20%, respectively. Comparisons between the NTM+ and NTM- cohorts revealed that NTM+ patients were more likely to be African-American and have cytomegalovirus mismatch. Although no difference was seen in survival, the NTM+ cohort was more likely to develop BOS (80% vs. 58%, P = 0.02). NTM+ infection, however, was not independently associated with development of BOS by multivariate analysis.

CONCLUSION

With nearly 20 years of follow-up, 14% of lung recipients develop NTM respiratory tract infections, with M. abscessus and MAC more commonly identified. M. gordonae was considered responsible for nearly 10% of NTM infections. Although survival of patients with NTM infections is similar, a striking difference in BOS rates is present in the NTM+ and NTM- groups.

Non-tuberculous mycobacterial infections in solid organ transplant recipients: An update

Non-tuberculous mycobacteria are ubiquitous environmental organisms that are now increasingly recognized as important causes of clinical disease in solid organ transplant recipients. Risk factors of non-tuberculous mycobacteria infection are severe immunologic defects and structural abnormalities. Lung transplant recipients are at higher risk for non-tuberculous mycobacterial disease compared to recipients of other solid organs. The clinical presentation could be skin and soft tissue infection, osteoarticular disease, pleuropulmonary infection, bloodstream (including catheter-associated) infection, lymphadenitis, and disseminated or multi-organ disease. Management of non-tuberculous mycobacteria infection is complex due to the prolonged treatment course with multi-drug regimens that are anticipated to interact with immunosuppressive medications. This review article provides an update on infections due to non-tuberculous mycobacteria after solid organ transplantation, and discusses the epidemiology, risk factors, clinical presentation, and management.

Early onset of nontuberculous mycobacterial pulmonary disease contributes to the lethal outcome in lung transplant recipients: report of two cases and review of the literature

Lung transplant (LuTx) recipients represent a population at risk of nontuberculous mycobacterial pulmonary disease (NTM-PD). Yet the risk factors, the timing of NTM-PD after transplantation, and the association with allograft dysfunction all remain poorly defined. We report 2 cases of early-onset NTM-PD and review the literature, focusing on NTM-PD in LuTx recipients not colonized with NTM prior to transplantation. In addition, we summarize the main characteristics and differences between early- and late-onset disease.

Lung transplantation for cystic fibrosis: results, indications, complications, and controversies

Survival in patients with cystic fibrosis (CF) has improved dramatically over the past 30 to 40 years, with mean survival now approximately 40 years. Nonetheless, progressive respiratory insufficiency remains the major cause of mortality in CF patients, and lung transplantation (LT) is eventually required. Timing of listing for LT is critical, because up to 25 to 41% of CF patients have died while awaiting LT. Globally, approximately 16.4% of lung transplants are performed in adults with CF. Survival rates for LT recipients with CF are superior to other indications, yet LT is associated with substantial morbidity and mortality (∼50% at 5-year survival rates). Myriad complications of LT include allograft failure (acute or chronic), opportunistic infections, and complications of chronic immunosuppressive medications (including malignancy). Determining which patients are candidates for LT is difficult, and survival benefit remains uncertain. In this review, we discuss when LT should be considered, criteria for identifying candidates, contraindications to LT, results post-LT, and specific complications that may be associated with LT. Infectious complications that may complicate CF (particularly Burkholderia cepacia spp., opportunistic fungi, and nontuberculous mycobacteria) are discussed.

Diseases caused by nontuberculous mycobacteria in Asia

 The isolation rate of nontuberculous mycobacteria (NTM) species and the prevalence of NTM-associated diseases are on the rise in Asian, as well as in Western countries; however, the species distribution of NTM isolates and the types of diseases caused by NTM species vary from region to region. In this review, we present an update on the epidemiology of NTM in Asia. We demonstrate that the distribution of NTM species varies within Asia and differs from that in North America and Europe. In addition, the clinical manifestations of NTM diseases include respiratory tract infections, disseminated infections, skin and soft tissue infections, lymphadenitis, empyema, ocular infections, CNS infections and genitourinary infections. Finally, the rate of adaptive resistance of anti-NTM antimicrobial agents remains high and may be associated with a poor outcome for patients with NTM diseases.

Tuberculosis and hematopoietic stem cell transplant: Review of a difficult and often underestimated problem

Recipients of solid organ transplants (SOT) and stem cell transplants (SCT) constitute a group of patients at risk for tuberculosis (TB) development. The prevalence of active TB in patients undergoing SOT is higher than in patients undergoing SCT, probably due to the shorter period of immunosuppression in the latter. We reviewed the importance of SCT in individuals with hematological malignancies. Most TB cases occur in transplant patients by reactivation of latent infection after immunosuppression, most often within the first year after transplant, leading to graft loss and in some cases, death. Relevant variables to assess the risk of TB infection in a transplant recipient include the donor’s and recipient’s medical histories, imaging results, microbiology and tuberculin skin test (TST) and interferon-gamma release assays (IGRA). TST is routinely performed in the donor and recipient before transplantation. If TST is > 5 mm in the recipient or > 10 mm in the donor, it is necessary to exclude active TB (pulmonary and renal). Chemoprophylaxis is recommended in TST (+) recipients and in recipients with recent seroconversion, in donors with a history of untreated TB or in contact with an individual with active TB, if radiological images are suspicious and the IGRA is (+). The drug of choice is isoniazid. These topics are herewith reviewed.

Clinical significance of respiratory isolates for Mycobacterium abscessus complex from pediatric patients

Mycobacterium abscessus complex is the most virulent of rapidly growing mycobacteria causing invasive lung disease. To better delineate clinical pediatric experience and outcomes with M. abscessus complex, we retrospectively gathered 5-year data on M. abscessus complex infection and outcomes in a large, hospital-based pediatric pulmonary center. Patients were selected from the database of the microbiology department at Miller Children's Hospital in Long Beach, CA. Patients had at least one positive pulmonary isolate for M. abscessus complex from February 2006 to May 2011. Treatment modality data were collected and successful therapy of disease was determined as clearance of M. abscessus complex infection after antibiotics proven by culture negative respiratory isolate within at least 12 months of therapy initiation. Two cystic fibrosis patients with M. abscessus complex were identified, one with failed therapy and the other with stable pulmonary status despite persistent isolation. One primary ciliary dyskinesia patient had successful clearance of M. abscessus complex, however is now growing M. avium intracellulare. A patient with no prior medical history was successfully treated with antimycobacterial therapy. Eleven patients with neuromuscular disorders had tracheal aspirates positive for M. abscessus complex. None were treated due to stable lung status and all but two had spontaneous clearance of the mycobacteria. The two remaining persist with sporadic isolation of M. abscessus complex without clinical significance. We concluded that patients with tracheostomy associated M. abscessus complex infections do not appear to require treatment and often have spontaneous resolution. Cystic fibrosis or primary ciliary dyskinesia patients may have clinical disease warranting treatment, but current antimycobacterial therapy has not proven to be completely successful. As M. abscessus complex gains prevalence, standardized guidelines for diagnosis and therapy are needed in the pediatric population. Multicenter cohort analysis is necessary to achieve such guidelines.

A case of empyema necessitatis caused by Mycobacterium abscessus

Non-tuberculosis mycobacteria (NTM) have emerged as an important pathogen in lung infection. NTM infection is rarely accompanied by pleural involvement, and empyema necessitatis caused by NTM is very uncommon. We report a very rare case of Mycobacterium abscessus pulmonary disease with empyema accompanied by empyema necessitatis. The patient was successfully treated by percutaneous tube drainage of the empyema and empyema necessitatis with aggressive antibiotics treatment and surgical resection.

Non-tuberculous mycobacterium infection after lung transplantation is associated with increased mortality

BACKGROUND

Pulmonary non-tuberculous mycobacterial (NTM) infection is relatively common after lung transplantation, but the effect on mortality remains undetermined. Herein we describe our experience with pulmonary NTM infection after lung transplantation and hypothesized that non-tuberculous mycobacterial infection after lung transplantation would be associated with increased mortality.

METHODS

We retrospectively evaluated 201 primary lung transplant recipients transplanted between January 2000 and August 2006. Serial bronchoscopies with bronchoalveolar lavage and transbronchial biopsy were performed according to a surveillance protocol and when clinically indicated. The diagnosis NTM infection was established by a positive NTM culture in a bronchoalveolar lavage sample or in at least two separate expectorated sputum samples. NTM infections were further classified as "disease" or "colonization," based on whether or not NTM infection patients developed symptoms and characteristic radiographic findings.

RESULTS

Thirty-six (18%) recipients were diagnosed with pulmonary NTM infection at a median of 97 days post-transplantation: 9 were classified as NTM disease and the remaining 27 as NTM colonization cases. Single lung transplant was a significant risk factor for NTM infection (HR 2.25, p = 0.02). NTM colonization was a risk factor for NTM disease (HR 8.39, p = 0.003). NTM infection significantly increased the risk of death after lung transplantation (HR 2.61, p = 0.001) and persisted in multivariate models controlling for single lung transplant and bronchiolitis obliterans syndrome. The increased risk was seen for both NTM colonization and NTM disease. Among the patients who died, non-NTM infection was a more common contributing factor in the cause of death for the NTM infection group (44% vs 12%, p = 0.04).

CONCLUSIONS

Non-tuberculous mycobacterial infection is common after lung transplantation. NTM colonization and treated acute rejection are risk factors for NTM disease. NTM infection is associated with increased risk of mortality independent of bronchiolitis obliterans syndrome.

Transplantation and tropical infectious diseases

The number of transplant recipients with tropical infectious diseases is growing due to increasing international travel and the rising number of transplants taking place in the tropics and subtropics. With increases in population migration, the prevalence of individuals infected with geographically restricted organisms also rises. There are three potential categories of tropical infections in transplant patients: (1) donor-related infections transmitted by the graft or through transfusion of blood products; (2) reactivation or recrudescence of latent infections in the donor recipient; and (3) de novo acquisition of infection in the post-transplant period through the traditional route of infection. We present an overall discussion of the association of parasitic (protozoa and helminths) and non-parasitic (viral, bacterial, and fungal) tropical infectious diseases and solid-organ and hematopoietic transplantation. We also suggest potential screening guidelines for some of these tropical infections.

Mycobacterium chelonae empyema in an immunocompetent patient

Thoracic empyema caused by rapidly growing mycobacteria (RGM) and complicated with bronchopleural fistula is rarely reported, especially in immunocompetent patients. A 53-year-old healthy woman presented initially with a productive cough and intermittent fever. The patient received a complete treatment course following an initial diagnosis of pulmonary tuberculosis. After the anti-tuberculosis agents were discontinued, a right thoracic empyema with bronchopleural fistula occurred, and the pathogens from both pus and sputum were identified as Mycobacterium chelonae. Thoracotomy with decortication and wedge resection of the right middle lung was performed, followed by clarithromycin plus ciprofloxacin therapy for 36 months. This patient has not suffered a relapse in the last 3 years. In addition to the experience of successful treatment, this case indicates that RGM such as M. chelonae can emerge as causative pathogens of thoracic empyema, even in healthy persons.

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.

Critical care perspective on immunotherapy in lung transplantation

Lung transplantation is now a viable therapeutic option in the care of patients with advanced pulmonary parenchymal or pulmonary vascular disease. Lung transplantation, however, with chronic posttransplant immunosuppression, creates a uniquely vulnerable population of patients likely to experience significant life-threatening complications requiring intensive care. The introduction of several novel immunosuppressive agents, such as sirolimus and mycophenolate mofetil, in conjunction with more established agents such as cyclosporine and tacrolimus, has greatly increased treatment options for lung transplant recipients and likely contributed to improved short-term transplant outcomes. Modern transplant immunosuppression, however, is associated with a host of complications such as opportunistic infections, renal failure, and thrombotic thrombocytopenic purpura. The main focus of this review is to provide a comprehensive summary of modern immunotherapy in lung transplantation and to increase awareness of the serious and potentially life-threatening complications of these medications.

Mycobacterium abscessus chest wall and pulmonary infection in a cystic fibrosis lung transplant recipient

Mycobacterial infections are increasingly recognized in cystic fibrosis (CF) patients before transplant; however, knowledge about the clinical significance or spectrum of infections observed with mycobacterial infections in lung transplant recipients is still evolving. Herein, we report a case of infection with Mycobacterium abscessus in a CF lung transplant recipient. Despite aggressive treatment before and peri-operatively with anti-mycobacterial therapy, the patient developed skin and soft tissue infection of the incision and of bilateral breast implants, eventually leading to disseminated pulmonary infection and death. This report highlights the potential for M abscessus to cause post-transplant disease in CF patients undergoing lung transplant, despite peri-operative anti-mycobacterial therapy. Thus, pre-transplant colonization with M abscessus should be viewed as a strong relative, if not absolute, contraindication to lung transplantation. The combination of the virulent pre-transplant pathogen M abscessus and foreign bodies in the chest likely acted synergistically to contribute to the unfortunate outcome in this patient.

Mycobacterium abscessus: an emerging rapid-growing potential pathogen. Review article

Mycobacterium abscessus is the most pathogenic and chemotherapy-resistant rapid-growing mycobacterium. It is commonly associated with contaminated traumatic skin wounds and with post-surgical soft tissue infections. It is also one of the mycobacteria that are most often isolated from cystic fibrosis patients. It is essential to differentiate this species from the formerly indistinct "M. chelonae-complex", as chemotherapy is especially difficult in M. abscessussenso strictu. Clarithromycin or azithromycin are the only regular oral antimycobacterial agents with an effect on M. abscessus, and should preferably be supplemented with other drugs since long-term monotherapy may cause resistance. Amikacin is a major parenteral drug against M. abscessus that should also be given in combination with another drug. The recently introduced drug tigecycline may prove to be an important addition to chemotherapy, but has yet to be fully clinically evaluated as an antimycobacterial agent. Surgery can be curative, or at least helpful, in the healing of M. abscessus infection, and if conducted, it should include the removal of all foreign or necrotic material. There is increasing awareness of M. abscessus as an emerging pathogen.

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.

Pneumonia due to Mycobacterium abscessus in two domestic ferrets (Mustelo putorius furo)

Two ferrets were diagnosed with pneumonia due to Mycobacterium abscessus. Both cases were treated successfully using clarithromycin after positive cultures were obtained via unguided bronchoalveolar lavage. This is the first time M abscessus has been isolated in our laboratory and the first report of this organism causing disease in companion animals in Australia. Underlying respiratory tract disease was thought to be an important factor in the development of the infections. Thorough investigation of chronic lower respiratory tract disease in ferrets is recommended as this species appears predisposed to atypical infections.

Human Metapneumovirus Infection in Lung Transplant Recipients: Clinical Presentation and Epidemiology

BACKGROUND

In immunocompromised patients, respiratory viruses are likely to lead to lower respiratory tract infections that cause severe morbidity and mortality. We conducted a prospective study from September 2003 to March 2004 to investigate the epidemiology and impact of human metapneumovirus (hMPV) on lung transplant recipients.

METHODS

We collected 265 nasopharyngeal aspirates and bronchoalveolar lavages: 51 samples originated from immunocompromised adults, 49 from lung transplant recipients, and 2 from a bone marrow recipient. Additionally, 209 samples from hospitalized non-immunocompromised children and 5 samples from immunocompromised children were analyzed for replicating hMPV by a combined cell culture and reverse transcriptase polymerase chain reaction method that includes DNA sequencing of selected isolates.

RESULTS

Twelve samples from lung transplant recipients (25%), 29 from non-immunocompromised children (14%), and 2 from a child with a renal transplant were positive for hMPV. Most of the cases clustered within 2 outbreaks in October/November and March. In immunocompromised patients, hMPV was isolated throughout the entire observation period. The same viral strains circulated in hospitalized children and in lung transplant recipients. A different strain was isolated during the interepidemic period, suggesting that hMPV infections may be transmitted among lung transplant recipients independently from the community outbreak situation. Clinical signs and symptoms varied from no symptoms to severe pneumonia or acute graft rejection. Significantly, the only deaths occurred in the hMPV-positive group. Of interest, identification of replicating hMPV significantly correlated with rejection symptoms present at the time point of sample collection.

CONCLUSIONS

Results of the study suggest that hMPV may be added to the list of pathogens that are possibly associated with episodes of allograft rejection.

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.

Nontuberculous mycobacterial infection in hematopoietic stem cell and solid organ transplant recipients

Nontuberculous mycobacteria (NTM) are ubiquitous environmental organisms. In immunocompetent hosts, they are a rare cause of disease. In immunocompromised hosts, disease due to NTM is well documented. Reports of NTM disease have increased in hematopoietic stem cell transplant (HSCT) and solid organ transplant (SOT) recipients. This increase may reflect increased numbers of transplants, intensification of immune suppressive regimens, prolonged survival of transplant recipients, and/or improved diagnostic techniques. The difficulty of diagnosis and the impact associated with infections due to NTM in HSCT and SOT recipients necessitates that, to ensure prompt diagnosis and early initiation of therapy, a high level of suspicion for NTM disease be maintained. The most common manifestations of NTM infection in SOT recipients include cutaneous and pleuropulmonary disease, and, in HSCT recipients, catheter-related infection. Skin and pulmonary lesions should be biopsied for histologic examination, special staining, and microbiologic cultures, including cultures for bacteria, Nocardia species, fungi, and mycobacteria. Mycobacterial infections associated with catheters may be documented by tunnel or blood (isolator) cultures. Susceptibility testing of mycobacterial isolates is an essential component of optimal care. The frequent isolation of NTM other than Mycobacterium avium complex (MAC) from transplant recipients limits the extrapolation of therapeutic data from human immunodeficiency virus-infected individuals to the population of transplant recipients. Issues involved in the management of NTM disease in transplant recipients are characterized by a case of disseminated infection due to Mycobacterium avium complex in a lung transplant recipient, with a review of the relevant literature.

Pulmonary disease caused by rapidly growing mycobacteria

The rapidly growing mycobacteria (RGM) differ from slow-growing mycobacteria such as Mycobacterium tuberculosis by virtue of their more rapid growth in culture media and their in vitro resistance to standard antituberculosis drugs. The RGM can produce numerous infections including chronic lung disease. The most common causes of pulmonary disease are Mycobacterium abscessus and Mycobacterium fortuitum. This article reviews the management of patients with lung disease caused by RGM.