Cytomegalovirus: the monster in the closet?

Prevalence and predictors of NTM in presumed/confirmed drug-resistant TB

INTRODUCTION

Non-tuberculous mycobacteria (NTM) are increasingly isolated in individuals with presumed/confirmed pulmonary TB. We aimed to estimate the prevalence and species distribution of NTM among presumed/confirmed drug-resistant TB (DR-TB) individuals and determine NTM isolation predictors.

METHODS

Sputum samples collected for DR-TB diagnosis and follow-up from 2012 to 2021 in Ghana were retrospectively analysed. Samples were subjected to sputum smear microscopy (SSM) and mycobacterial culture. The MPT64 assay was performed on positive cultures to distinguish between Mycobacterium tuberculosis complex MTBc and NTM. NTM isolates were re-cultured for species identification using GenoType® Mycobacterium CM/AS line-probe assay, polymerase chain reaction, and Sanger sequencing targeting 16S rRNA and rpoB genes. MTBc isolates identified by GenoType underwent spoligotyping. A logistic regression model was used to identify the predictors of NTM isolation.

RESULTS

Of the 2,492 samples, 839 (33.7%) tested culture-positive for mycobacteria, with 257 (30.6%) presumed to be NTM. Of these, 53 (23.6%) were identified at the species level, with a predominance of M. intracellulare (66.0%). MPT64 testing missed 18 (3%) MTBc isolates. Logistic regression showed increased odds of NTM isolation in follow-up samples (aOR 2.41, 95% CI 1.46-3.99). NTM species were isolated from 46 patients, with four classified as NTM pulmonary disease.

CONCLUSION

Enhancing our understanding of local NTM epidemiology and improving local diagnostic capabilities can optimise patient management strategies and outcomes.

Evaluation of Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry for Identification of Mycobacterium abscessus Subspecies According to Whole-Genome Sequencing

This study was undertaken to evaluate the utility of matrix-assisted laser desorption ionization-time of flight mass spectrometry with the Vitek MS Plus system for identifying Mycobacterium abscessus subspecies in order to facilitate more rapid and appropriate therapy. A total of 175 clinical M. abscessus strains were identified by whole-genome sequencing analysis: 139 Mycobacterium abscessus subsp. abscessus and 36 Mycobacterium abscessus subsp. massiliense The research-use-only (RUO) Saramis Knowledge Base database v.4.12 was modified accordingly by adding 40 M. abscessus subsp. abscessus and 19 M. abscessus subsp. massiliense reference spectra to construct subspecies SuperSpectra. A blind test, used to validate the remaining 116 isolates, yielded 99.1% (n = 115) reliability and only 0.9% (n = 1) error for subspecies identification. Among the two subspecies SuperSpectra, two specific peaks were found for M. abscessus subsp. abscessus and four specific peaks were found for M. abscessus subsp. massiliense Our study is the first to report differential peaks 3,354.4 m/z and 6,711.1 m/z, which were specific for M. abscessus subsp. massiliense Our research demonstrates the capacity of the Vitek MS RUO Saramis Knowledge Base database to identify M. abscessus at the subspecies level. Moreover, it validates the potential ease and accuracy with which it can be incorporated into the IVD system for the identification of M. abscessus subspecies.

Pathogen profiles and molecular epidemiology of respiratory viruses in Japanese inpatients with community-acquired pneumonia

Background

The etiological profile of viruses among adult patients with community-acquired pneumonia (CAP) has not been characterized yet. The aim of this study was twofold: first, investigate the pathogen profiles and the molecular epidemiology of respiratory viruses among Japanese CAP patients; and second, explore the clinical significance of viral infections.

Methods

A cross-sectional observational study was conducted at Kyorin University Hospital. To identify respiratory pathogens, hospitalized CAP patients were enrolled, and reverse transcriptase–polymerase chain reaction technology was applied alongside conventional microbiological methods. Phylogenetic and pairwise distance analyses of 10 viruses were performed. CAP patients were divided into four etiological groups (virus alone, bacteria alone, co-detection of virus and bacteria, and not detected) and the clinical findings were compared.

Results

Seventy-six patients were enrolled. Bacteria alone were detected in 39.5% (n=30) of CAP patients. Virus alone or co-detection were found in 10.5% (n=8) and 11.8% (n=9) of cases, respectively. Streptococcus pneumoniae and human metapneumovirus were the most frequently detected bacterium and virus, respectively. Phylogenetic analyses of human metapneumovirus, human rhinovirus, and human respiratory syncytial virus showed that different subgroups and genotypes might be associated with CAP. Respiratory failure was more common when a virus was detected (both virus alone and co-detection groups; n=17, 100%, p<0.05) than when a bacteria alone was detected (n=17, 56.7%).

Conclusion

Prevalence of respiratory virus infection in CAP inpatients was 22.3%. The detected viruses display high genetic divergence and correlate with increased respiratory failure.

Intermittent antibiotic therapy for nodular bronchiectatic Mycobacterium avium complex lung disease

RATIONALE

Although intermittent, three-times-weekly therapy is recommended for the initial treatment of noncavitary nodular bronchiectatic Mycobacterium avium complex (MAC) lung disease, supporting data are limited.

OBJECTIVES

To evaluate the clinical efficacy of intermittent therapy compared with daily therapy for nodular bronchiectatic MAC lung disease.

METHODS

A retrospective cohort study of 217 patients with treatment-naive noncavitary nodular bronchiectatic MAC lung disease. All patients received either daily (n = 99) or intermittent therapy (n = 118) that included clarithromycin or azithromycin, rifampin, and ethambutol.

MEASUREMENTS AND MAIN RESULTS

Modification of the initial antibiotic therapy occurred more frequently in the daily therapy group than in the intermittent therapy group (46 vs. 21%; P < 0.001); in particular, ethambutol was more frequently discontinued in the daily therapy group than in the intermittent therapy group (24 vs. 1%; P ≤ 0.001). However, the rates of symptomatic improvement, radiographic improvement, and sputum culture conversion were not different between the two groups (daily therapy vs. intermittent therapy: 75 vs. 82%, P = 0.181; 68 vs. 73%, P = 0.402; 76 vs. 67%, P = 0.154, respectively). In addition, the adjusted proportion of sputum culture conversion was similar between the daily therapy (71.3%; 95% confidence interval, 59.1-81.1%) and the intermittent therapy groups (73.6%; 95% confidence interval, 62.9-82.2%; P = 0.785).

CONCLUSIONS

These results suggest that intermittent three-times-weekly therapy with a macrolide, rifampin, and ethambutol is a reasonable initial treatment regimen for patients with noncavitary nodular bronchiectatic MAC lung disease. Clinical trial registered with www.clinicaltrials.gov (NCT 00970801).

Clinical review: Respiratory failure in HIV-infected patients--a changing picture

Respiratory failure in HIV-infected patients is a relatively common presentation to ICU. The debate on ICU treatment of HIV-infected patients goes on despite an overall decline in mortality amongst these patients since the AIDS epidemic. Many intensive care physicians feel that ICU treatment of critically ill HIV patients is likely to be futile. This is mainly due to the unfavourable outcome of HIV patients with Pneumocystis jirovecii pneumonia who need mechanical ventilation. However, the changing spectrum of respiratory illness in HIV-infected patients and improved outcome from critical illness remain under-recognised. Also, the awareness of certain factors that can affect their outcome remains low. As there are important ethical and practical implications for intensive care clinicians while making decisions to provide ICU support to HIV-infected patients, a review of literature was undertaken. It is notable that the respiratory illnesses that are not directly related to underlying HIV disease are now commonly encountered in the highly active antiretroviral therapy (HAART) era. The overall incidence of P. jirovecii as a cause of respiratory failure has declined since the AIDS epidemic and sepsis including bacterial pneumonia has emerged as a frequent cause of hospital and ICU admission amongst HIV patients. The improved overall outcome of HIV patients needing ICU admission is related to advancement in general ICU care, including adoption of improved ventilation strategies. An awareness of respiratory illnesses in HIV-infected patients along with an appropriate diagnostic and treatment strategy may obviate the need for invasive ventilation and improve outcome further. HIV-infected patients presenting with respiratory failure will benefit from early admission to critical care for treatment and support. There is evidence to suggest that continuing or starting HAART in critically ill HIV patients is beneficial and hence should be considered after multidisciplinary discussion. As a very high percentage (up to 40%) of HIV patients are not known to be HIV infected at the time of ICU admission, the clinicians should keep a low threshold for requesting HIV testing for patients with recurrent pneumonia.

CT findings of pulmonary non-tuberculous mycobacterial infection in non-AIDS immunocompromised patients: a case-controlled comparison with immunocompetent patients

OBJECTIVE

To describe CT findings of non-tuberculous mycobacteria (NTM) pulmonary infection in non-AIDS immunocompromised patients (ICPs) and to compare these findings with those in immunocompetent patients.

METHODS

From July 2000 to August 2007, 369 patients (mean age 58.3 years; 169 males and 200 females) with pulmonary NTM infection were retrospectively reviewed. Of these 369 patients, 24 ICPs (mean age 64.8 years; 15 males and 9 females) were identified. 16 patients had diabetes mellitus, and 6 patients had received long-term steroid therapy. One had received solid organ transplantation and one had received high-dose chemotherapy for haematological disease. 24 age- and sex-matched immunocompetent patients (mean age 64.6 years; 15 males and 9 females) were selected as the control group from the same registry. CT images were reviewed in consensus by three chest radiologists, who were blinded to immune status. Each lung lobe was evaluated in terms of extent of the lesion, bronchiectasis, parenchymal opacity and the presence of ancillary findings. results: A total of 287 lobes were evaluated in ICPs and the control group. The ICPs showed a higher prevalence of ill-defined nodules, with cavities and large opacity >2 cm with/without cavity (p=0.03, 0.04 and 0.02, respectively). Regardless of the immune status, the most common CT findings were bronchiectasis and ill-defined nodules without cavity.

CONCLUSION

The most common CT findings of pulmonary NTM infection in ICPs were bronchiectasis and ill-defined nodules, similar to those in the control group. Ill-defined nodules with cavity and large opacity >2 cm with/without cavity were more frequently found in ICPs.

ADVANCES IN KNOWLEDGE

In patients affected by NTM infection, large opacities and cavitation in pulmonary nodules are more frequent in ICPs than in immunocompetent patients.

[Identification of Nontuberculous Mycobacteria by Sequence Analysis of the 16S Ribosomal RNA, the Heat-shock Protein 65 and the RNA Polymerase beta-Subunit Genes.]

BACKGROUND

The diagnosis of diseases caused by nontuberculous mycobacteria (NTM) is difficult, because NTM are prevalent in the environment such as soil and water, and because they have fastidious properties. In this study we investigated clinical isolates of NTM for their distribution pattern and accurate species identification.

METHODS

We selected presumptive NTM isolates negative for probe hybridization for M. tuberculosis complex, cultured in a third referral hospital from 21 January 2003 to 20 January 2004. Ninety seven-isolates were identified to the species level by direct sequencing of fragments of 16S rRNA, hsp65 and rpoB genes. A total of 120 isolates were studied for the distribution analysis.

RESULTS

Frequently identified NTM species were M. avium (30.8%), M. intracellulare (23.3%) and M. abscessus (18.3%). Others were M. gordonae, M. senegalense, M. fortuitum, M. peregrinum, M. kansasii, M. terrae complex, M. lentiflavum, M. chelonae, and M. szulgai. Three M. tuberculosis complex (2.5%) were also identified among the presumptive NTM isolates. The identification rate by sequencing of 16S rRNA, rpoB, and hsp65 were 65%, 82% and 87%, respectively. The hsp65 or rpoB gene was more efficient than 16S rRNA for the identification of NTM by sequencing.

CONCLUSIONS

Some NTM are increasingly considered to be the causative organisms in clinical diseases. Thus, direct sequencing could be adapted to routine work of clinical laboratories for accurate identification of NTM to the species level.

History of antibiotics. From salvarsan to cephalosporins

Infections have represented for a long time the leading cause of death in humans. During the 19th century, pneumonia, tuberculosis, diarrhea and diphtheria were considered the main causes of death in children and adults. Only in the late 19th century did it become possible to correlate the existence of microscopic pathogens with the development of various diseases. Within a few years the introduction of antiseptic procedures had begun to reduce mortality due to postsurgical infections. Sanitation and hygiene played a significant role in the reduction of the mortality due to several infectious diseases. The introduction of the first compounds with antimicrobial activity succeeded in conquering many diseases. In this review we analyzed, from a historical perspective, the development of antibiotics and the circumstances that led to their discovery. The first compound with antimicrobial activity was introduced in 1911 by Erlich. He focused his research activity on the discovery of a "magic bullet" to treat syphilis. Afterwards, Foley and colleagues brought penicillin to the forefront. Streptomycin represents the first drug discovered for the treatment of tuberculosis, and its development included the first use of clinical trials. Finally, with the development of cephalosporins, the introduction of new antimicrobial compounds with broad activity against gram-positive and also some gram-negative bacteria began.

Clinical significance and antibiotic susceptibilities of nontuberculous mycobacteria from patients in Crete, Greece

AIM

To describe the clinical significance and antibiotic susceptibilities of nontuberculous mycobacteria (NTM) isolated from patients in Crete, Greece between January 2000 and December 2009.

PATIENTS & METHODS

NTM identification was performed using conventional bacteriological methods and confirmed by molecular characterization with commercially available assays. Rare and novel species were identified by sequencing of the 16SrRNA and of the hsp65 genes. Antibiotic susceptibility testing was performed by E-test. Rapidly growing (RGM) and slowly growing (SGM) NTM were tested against 14 antimicrobials, including nine common ones, except for Mycobacterium avium and Mycobacterium intracellulare (MAC) complex isolates that were tested only against azithromycin, clarithromycin, linezolid and moxifloxacin.

RESULTS

During the study period, 290 positive samples for NTM were recovered from 207 patients. Among the positive samples, 150 were identified as SGM and 57 as RGM. Overall, 50 patients met American Thoracic Society criteria for disease due to NTM, 42 by SGM and eight by RGM. Risk factors in patients with NTM disease were underlying lung diseases, mainly chronic obstructive pulmonary disease and asthma, smoking, rheumatoid arthritis, AIDS, alcohol or drug abuse, malignancies and bronchiectasis. The most common disease-causing species were the MAC complex (n = 25) followed by Mycobacterium kansasii (n = 10). Amikacin was the most active drug for RGM with 100% susceptibility. Macrolides were very active against isolates of the MAC complex, while tigecycline had excellent activity in vitro against RGM. M. kansasii was the most susceptible NTM species in vitro.

CONCLUSION

Our study is the first to describe the clinical significance, risk factors and susceptibility patterns of NTM isolates in a Greek population.

Targeted delivery of amikacin into granuloma

RATIONALE

Nontuberculous mycobacterial (NTM) infection is a growing problem in the United States and remains underrecognized in the developing world. The management of NTM infections is further complicated by several factors, including the need to use high systemic doses of toxic agents, the length of therapy, and the development of drug resistance.

OBJECTIVES

We have evaluated the use of monocyte-derived dendritic cells (DCs) as a delivery vehicle for a luminescent derivative of amikacin prepared by conjugation to fluorescein isothiocyanate (FITC) (amikacin-FITC) into granulomas formed in the tissues of mice infected with Mycobacterium avium.

METHODS

Amikacin-FITC was prepared and quantitative fluorescence was used to track the intracellular uptake of this modified antibiotic. The antibiotic activity of amikacin-FITC was also determined to be comparable to unmodified amikacin against M. avium. Amikacin-FITC-loaded DCs were first primed with M. avium, and then the cells were injected into the tail vein of infected mice. After 24 hours, the mice were sacrificed and the tissues were analyzed under fluorescence microscope.

MEASUREMENTS AND MAIN RESULTS

We found that we were able to deliver amikacin into granulomas in a mouse model of disseminated mycobacterial infection. No increase in levels of monocyte chemoattractant protein-1 and its CCR2 as markers of inflammation were found when DCs were treated with amikacin-FITC.

CONCLUSIONS

DC-based drug delivery may be an adjunct and useful method of delivering high local concentrations of antibiotics into mycobacterial granulomas.

Standardized combination antibiotic treatment of Mycobacterium avium complex lung disease

PURPOSE

The optimal treatment regimen for Mycobacterium avium complex (MAC) lung disease has not yet been fully established. We evaluated the efficacy of standardized combination antibiotic therapy and the factors that might affect unfavorable microbiologic responses in patients with MAC pulmonary disease.

MATERIALS AND METHODS

This retrospective study reviewed data from 96 patients (56 females; median age 59 years) treated with newly diagnosed MAC lung disease between January 2003 and December 2006.

RESULTS

All patients received standardized combination antibiotic therapy, consisting of clarithromycin, rifampicin, and ethambutol. Streptomycin was additionally given in 72 patients (75%) for a median duration of 4.5 months. The overall favorable microbiologic response rate was 79% (76/96); 20 patients (21%) had unfavorable microbiologic responses, including failure to sputum conversion (n = 13), relapse (n = 3), and MAC-related death (n = 4). A positive sputum acid-fast bacillus smear at the start of treatment was an independent predictor of an unfavorable microbiologic response.

CONCLUSION

Standardized combination antibiotic therapy consisting of clarithromycin, rifampicin, and ethambutol with or without initial use of streptomycin is effective in treating patients with newly diagnosed MAC lung disease.

Viral pneumonias in immunocompromised adult hosts

Viral infections have always been considered pediatric diseases. However, viral pneumonia has become an important cause of morbidity and mortality in immuncompromised adults. Improved diagnostic techniques, such as the introduction of highly sensitive nucleic acid amplification tests, have not only allowed us to discover new viruses but also to determine the etiology of viral pneumonia in immunocompromised adult hosts. Unfortunately, only a few antiviral agents are available. Thus, early diagnosis and treatment are crucial to patient outcome. In this article, we review the most common viruses that have been implicated as etiologic agents of viral pneumonia in immunocompromised adults. We discuss the epidemiologic characteristics and clinical presentation of these viral infections and the most appropriate diagnostic approaches and therapies when available.

Clinical significance of differentiation of Mycobacterium massiliense from Mycobacterium abscessus

RATIONALE

Mycobacterium massiliense has been recognized as a separate species from Mycobacterium abscessus; however, little is known regarding the clinical impact of this differentiation.

OBJECTIVES

To compare clinical features and treatment outcomes between patients with M. abscessus lung disease and those with M. massiliense lung disease.

METHODS

We performed molecular identification of stored clinical isolates of M. abscessus complex and compared clinical characteristics and treatment outcomes between 64 patients with M. abscessus lung disease and 81 patients with M. massiliense lung disease.

MEASUREMENTS AND MAIN RESULTS

The clinical and radiographic manifestations of disease caused by each species were similar. Standardized combination antibiotic therapy, including a clarithromycin-containing regimen in combination with an initial 4-week course of cefoxitin and amikacin, was given to 57 patients (24 with M. abscessus and 33 with M. massiliense) for more than 12 months. The proportion of patients with sputum conversion and maintenance of negative sputum cultures was higher in patients with M. massiliense infection (88%) than in those with M. abscessus infection (25%; P < 0.001). Inducible resistance to clarithromycin (minimal inhibitory concentrations ≥ 32 μg/ml) was found in all tested M. abscessus isolates (n = 19), but in none of the M. massiliense isolates (n = 28).

CONCLUSIONS

Treatment response rates to combination antibiotic therapy including clarithromycin were much higher in patients with M. massiliense lung disease than in those with M. abscessus lung disease. The inducible resistance to clarithromycin could explain the lack of efficacy of clarithromycin-containing antibiotic therapy against M. abscessus lung disease.

Consolidations in nodular bronchiectatic Mycobacterium avium complex lung disease: Mycobacterium avium complex or other infection?

PURPOSE

The objective of this study is to define the clinical implications of consolidations in nodular bronchiectatic type Mycobacterium avium complex (NBMAC) infection.

MATERIALS AND METHODS

A total of 69 patients (M : F = 17 : 52; mean age, 64 years; age range, 41-85 years) with MAC isolated in the sputum culture and nodular bronchiectasis on the initial and follow-up CT scans were included. We retrospectively reviewed the incidence of consolidation and analyzed its clinical course by using radiographic changes with or without anti-MAC drug therapy.

RESULTS

In 44 of the 69 cases (64%), focal consolidations were seen on the initial and follow-up CT images. In 35 of the 44 (80%) cases, consolidations completely regressed, and in 3 cases (7%), consolidations partially regressed within 2 months with only antibiotics. In 2 cases (5%), the consolidations remained stable for over 2 months without anti-MAC drug therapy. Only in 4 cases (9%) did the consolidations improve after anti-MAC drug therapy. In 11 of the 38 cases (29%) with responsiveness to antibiotics, non-mycobacterial micro-organisms were identified in sputum, including pseudomonas, hemophilus, staphylococcus, and others.

CONCLUSION

In NB-MAC, consolidations are commonly present on CT. In these conditions, most of consolidations result from pneumonia other than MAC.

Exhaled 8-isoprostane in sarcoidosis: relation to superoxide anion production by bronchoalveolar lavage cells

Objective

This study was designed to examine the mutual relationship between 8-isoprostane in exhaled breath condensate (EBC) and superoxide anion generation by bronchoalveolar lavage fluid (BALF) cells in patients with sarcoidosis.

Design

About 29 patients with sarcoidosis, 34 healthy never smokers (control group for EBC) and 15 healthy never smokers (control group for BAL) were examined. EBC was collected directly before bronchoscopy. 8-Isoprostane was measured by ELISA, and superoxide anion by colorimetry.

Results

Exhaled breath condensate 8-isoprostane is increased in sarcoidosis (median, 25–75 percentile): 2.50; 2.50–3.90 versus 6.20; 2.50–16.95 pg/ml, p ≤ 0.05). Spontaneous superoxide anion release from BALF cells was significantly elevated only in patients with a high percentage of lymphocytes in BALF (6.42 ± 1.24 vs. 23.52 ± 4.30 nmol/10⁶ cells, p ≤ 0.01). There were no correlations between 8-isoprostane and spontaneous or stimulated superoxide anion release.

Conclusions

We confirmed higher concentrations of EBC 8-isoprostane in sarcoidosis and higher spontaneous release of superoxide anion from BALF cells in patients with sarcoidosis. The increase of EBC 8-isoprostane is not directly related to superoxide anion released from BALF cells.

Bone marrow infection caused by Mycobacterium avium complex in a patient with systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a disease with wide range of signs and symptoms. SLE patients have increased infective diathesis, and infections are a very important cause of death in these patients. Infections can sometimes mimic the signs and symptoms of SLE. Thus, it is important to recognize that infection can induce a lupus flare-up or can be difficult to distinguish from a lupus flare-up. We describe a 36-year-old female patient with SLE, who presented with skin lesions and pancytopenia, and clinical manifestations similar to a flare-up of SLE. Bone marrow examination revealed infection with Mycobacterium avium complex (MAC). The patient had no history or clinical evidence of pulmonary involvement. This patient is the first case of invasive bone marrow MAC infection in SLE. With this unique case, we would like to emphasize that SLE patients can also be infected by non-tuberculous mycobacteria, and that bone marrow examination for tuberculosis as well as for non-tuberculosis mycobacteria should be considered in SLE patients with refractory pancytopenia.

Multicenter study of prevalence of nontuberculous mycobacteria in patients with cystic fibrosis in france

We performed a multicenter prevalence study of nontuberculous mycobacteria (NTM) involving 1,582 patients (mean age, 18.9 years; male/female ratio, 1.06) with cystic fibrosis in France. The overall NTM prevalence (percentage of patients with at least one positive culture) was 6.6% (104/1,582 patients), with prevalences ranging from 3.7% (in the east of France) to 9.6% (in the greater Paris area). Mycobacterium abscessus complex (MABSC; 50 patients) and Mycobacterium avium complex (MAC; 23 patients) species were the most common NTM, and the only ones associated with fulfillment of the American Thoracic Society bacteriological criteria for NTM lung disease. The "new" species, Mycobacterium bolletii and Mycobacterium massiliense, accounted for 40% of MABSC isolates. MABSC species were isolated at all ages, with a prevalence peak between 11 and 15 years of age (5.8%), while MAC species reached their highest prevalence value among patients over 25 years of age (2.2%).

Antibiotic treatment of Mycobacterium abscessus lung disease: a retrospective analysis of 65 patients

RATIONALE

The optimal therapeutic regimen and duration of treatment for Mycobacterium abscessus lung disease is not well established.

OBJECTIVES

To assess the efficacy of a standardized combination antibiotic therapy for the treatment of M. abscessus lung disease.

METHODS

Sixty-five patients (11 males, 55 females, median age 55 yr) with M. abscessus lung disease were treated with clarithromycin, ciprofloxacin, and doxycycline, together with an initial regimen of amikacin and cefoxitin for the first 4 weeks of hospitalization.

MEASUREMENTS AND MAIN RESULTS

Treatment response rates were 83% for symptoms and 74% for high-resolution computed tomography. Sputum conversion and maintenance of negative sputum cultures for more than 12 months was achieved in 38 (58%) patients. These rates were significantly lower in patients whose isolates were resistant to clarithromycin (17%, 2/12) compared with those whose isolates were susceptible or intermediate to clarithromycin (64%, 21/33; P = 0.007). Neutropenia and thrombocytopenia associated with cefoxitin developed in 33 (51%) and 4 (6%) patients, respectively. Drug-induced hepatotoxicity occurred in 10 (15%) patients. Because of these adverse reactions, cefoxitin was discontinued in 39 (60%) patients after treatment for a median of 22 days.

CONCLUSIONS

Standardized combination antibiotic therapy was moderately effective in treating M. abscessus lung disease. However, frequent adverse reactions and the potential for long-duration hospitalization are important problems that remain to be solved.

Non-tuberculous mycobacterial infections

Non-tuberculous mycobacteria (NTM) are ubiquitous environmental organisms in contrast to those belonging to the M. tuberculosi complex (MTB). NTM infects and causes disease only in hosts with local or general predisposing factors. Lung infection following inhalation of NTM is the most common NTM disease but soft tissue infections may occur in connection with contaminated trauma or surgery. Microbiological diagnosis is obtained by microscopy for acid-fast bacteria (AFB) on secretions or biopsies, and by culture on special media. With the high specificity of MTB- polymerase chain reaction (PCR), a positive AFB smear combined with negative MTB-PCR denotes infection with NTM. Sophisticated species diagnosis of cultured NTM is attained by various molecular methods, where 16S rDNA-sequencing remains the gold standard. The panorama of infection with different rapidly growing (RGM) or slowly growing mycobacteria (SGM) in Sweden is described. Sensitivity testing in vitro to antimycobacterial drugs against NTM does not always preclude the in vivo efficacy. Standard antimycobacterial treatment regimens have been defined for infection with several NTM species. Sensitivity testing should be performed in selected cases only, as in case of relapse or suspected development of resistance of the NTM strain. The spectrum of disease caused by NTM species that display a very low pathogenic potential is likely to widen over time as severe immunosuppression will continue to be prevalent in several patient categories.

Comparison of clinical and radiographic characteristics between nodular bronchiectatic form of nontuberculous mycobacterial lung disease and diffuse panbronchiolitis

The nodular bronchiectatic form of nontuberculous mycobacterial (NTM) lung disease and diffuse panbronchiolits (DPB) show similar clinical and radiographic findings. The present study was performed to clarify the clinicoradiographic similarities as well as the differences between NTM lung disease and DPB. The initial clinicoradiographic features of 78 patients with the nodular bronchiectatic form of NTM lung disease (41 patients with Mycobacterium avium complex infection and 37 patients with Mycobacterium abscessus infection) were compared with those of 35 patients with DPB. Old age, female sex, a history of tuberculosis treatment, and hemoptysis were related to NTM lung disease while exertional dyspnea, coarse crackles, history of sinusitis, obstructive abnormalities in pulmonary function tests, and hypoxemia were related to DPB. The number of lobes involved with bronchiolitis and bronchiectasis on chest computed tomography were more numerous in DPB patients. There is considerable overlap in the clinical and radiographic appearances of the nodular bronchiectatic form of NTM lung disease and DPB, although some clinicoradiographic features differ between two diseases. The correct diagnosis, including aggressive microbiologic evaluation, should be made for the appropriate management of patients presenting with bilateral bronchiectasis and bronchiolitis.

Clarithromycin susceptibility testing of Mycobacterium avium complex using 2,3-diphenyl-5-thienyl-(2)-tetrazolium chloride microplate assay with Middlebrook 7H9 broth

A series of 119 Mycobacterium avium complex isolates were subjected to clarithromycin susceptibility testing using microplates containing 2,3-diphenyl-5-thienyl-(2)-tetrazolium chloride (STC). Among 119 isolates, 114 (95.8%) were susceptible to clarithromycin and 5 were resistant according to the new and the standard method. STC counts the low cost and reduces the number of procedures needed for susceptibility testing.

Nontuberculous mycobacterial infections among patients suspected of pulmonary tuberculosis

The purpose of this study was to present a retrospective analysis of the frequency of nontuberculous mycobacteria (NTM)-related pulmonary infections among the AFB-positive and/or culture-positive patients in the Warsaw region who were suspected of tuberculosis (TB) and hospitalized in the university hospital between 1999 and 2005. All the AFB-positive pulmonary samples were examined with a molecular method using the Amplicor MTB test (Roche) for detection of Mycobacterium tuberculosis complex, and all mycobacterial isolates were speciated by high performance liquid chromatography (HPLC) analysis of mycolic acids. Patients who met clinical, radiological, and bacteriological criteria of mycobacteriosis were classified according to the American Thoracic Society (ATS) guidelines for diagnosis of NTM related disease. Among the 445 smear-positive or/and culture-positive patients, 142 subjects (31.9%) were found to be infected with M. tuberculosis. Among 303 non-TB patients, mycobacteriosis was found in 27 (8.9%) subjects. The frequency of NTM-related lung disease as compared to the bacteriologically-confirmed lung TB was estimated at 1:5. The rapid, precise methods of NTM speciation are necessary for progress in diagnostics of NTM related diseases.

Evaluation of an immunochromatographic assay kit for rapid identification of Mycobacterium tuberculosis complex in clinical isolates

We evaluated a new immunochromatographic assay (ICA) using mouse monoclonal anti-MPT64 antibody for rapid discrimination between Mycobacterium tuberculosis and nontuberculous mycobacteria in clinical isolates. A study with mycobacteria and other organisms showed excellent sensitivity (approximately equal 99%) and specificity (100%) and an appropriate detection limit (10(5) CFU/ml) when tested with M. tuberculosis H37Rv. This ICA can simplify the identification of M. tuberculosis in clinical laboratories.

Mykobakterien, nichttuberkulöse (NTM)

Atypische, ubiquitäre, Umwelt-Mykobakterien, „Mycobacteria other than Mycobacterium tuberculosis“ MOTT

[Identification of mycobacteria species by HPLC and species distribution during five years at Ulsan university hospital]

BACKGROUND

Infections caused by mycobacteria have been significantly increasing. Due to the difficulty of making a decision about the pathogenicity of mycobacteria, species-level identification is very important for patients' diagnosis and treatment. The purpose of this study was to identify mycobacteria species using a high performance liquid chromatography (HPLC) method and to provide an initial database for the distribution of mycobacteria in Korea.

METHODS

Acid fast bacteria isolated from 3,107 clinical specimens were identified by mycolic acid analysis using HPLC. The HPLC patterns were compared with those of standard mycobacteria species.

RESULTS

The HPLC patterns were divided into single, double, and triple cluster groups, each group comprising 9, 20, and 4 species, respectively. Mycobacteria and non-tuberculous mycobacteria (NTM) were identifies by HPLC at the rates of 99.5% and 95.6%, respectively. NTM was isolated in 12.4% of the mycobacteria positive specimens. This study also found that there were 20 different NTM species with the distribution of each species ranging from 0.3% to 15.9% of the total NTM. While the rate of NTM has been increasing in Korea, M. avium-intracellulare, M. fortuitum, and M. chelonae are relatively decreasing, and M. kansasii and M. gordonae are relatively increasing.

CONCLUSIONS

HPLC method was highly discriminative for the identification of NTM in clinical specimens.

First case of Mycobacterium heckeshornense lymphadenitis

Mycobacterium heckeshornense is a slow-growing nontuberculous mycobacterium first characterized in 2000. It is reported to cause lung disease and tenosynovitis. We report a case of isolated massive axillary lymphadenopathy in an elderly woman, where histology showed necrotizing granulomata and M. heckeshornense was isolated as the causative organism.

Spondylodiscitis caused by Mycobacterium xenopi

The infection with non-tuberculous mycobacterium correlates highly with immunodeficiency. Mycobacterium xenopi (M. xenopi) is most commonly isolated in the respiratory tract, as a cause of endogenous spondylodiscitis it occurs but rarely. Only seven such cases have been reported in literature. In this paper, we present the case of an about 28-year-old HIV-positive patient with a long history of back pain. MRI of the spinal column and Positron Emission Tomography with (18)F-fluorodeoxyglucose as a tracer (F18-FDG-PET) confirmed the suspected spondylodiscitis. After performing a CT-controlled abscess drainage the patient's condition improved. Because of the severe destruction of the spinal segment concerned and because of the epidural abscess formation a vertebrectomy of T10 and surgical debridement of the paravertebral soft tissue via thoracotomy became urgently necessary. The spine was stabilized by interposing a cage and an anterolateral monobar system. M. xenopi could be proven by PCR out of the intraoperative specimen. After operation and antituberculotic therapy there was a fast convalescence. Diagnostics, therapy, and clinical outcome are discussed.

An association between Mycobacterium malmoense and coal workers' pneumoconiosis

An association between Mycobacterium malmoense and underlying lung disease has been described. The purpose of this study was to further explore this relationship and in particular to identify any relationship between Coal Workers' Pneumoconiosis (CWP) and M. malmoense infection. Patient charts were reviewed of all patients who had a positive sputum or bronchoalveolar lavage for M. malmoense from 1999 to 2006 in a large district general hospital in South Yorkshire, UK. We also performed a literature review in search of this association; one case report was found. Four patients had positive sputum cultures for M. malmoense but only three of these fulfilled the ATS 1997 criteria for diagnosis of disease. Of these three patients, all had clinical and radiologic evidence of CWP. This study strengthens the evidence of a link between nontuberculous mycobacteria and underlying lung disease but more importantly highlights an association between M. malmoense and CWP which has been rarely reported and is poorly understood.

Proportions of Mycobacterium massiliense and Mycobacterium bolletii strains among Korean Mycobacterium chelonae-Mycobacterium abscessus group isolates

Korean isolates of the Mycobacterium chelonae-Mycobacterium abscessus group, which had been isolated from two different hospitals in South Korea, were identified by PCR restriction analysis (PRA) and comparative sequence analysis of 16S rRNA genes, rpoB, and hsp65 to evaluate the proportion of four closely related species (M. chelonae, M. abscessus, M. massiliense, and M. bolletii). Of the 144 rapidly growing mycobacterial strains tested, 127 strains (88.2%) belonged to the M. chelonae-M. abscessus group. In this group, M. chelonae, M. abscessus, M. massiliense, and M. bolletii accounted for 0.8% (n = 1), 51.2% (n = 65), 46.5% (n = 59), and 1.6% (n = 2), respectively. Two isolates which showed discordant results, M. massiliense by rpoB sequence analysis and M. abscessus by hsp65 sequence analysis, were finally identified as M. massiliense based on the additional analysis of sodA and the 16S-23S internal transcribed spacer. M. abscessus group I isolates previously identified by hsp65 PRA were all found to be M. abscessus, whereas group II isolates were further identified as M. massiliense or M. bolletii by sequencing of rpoB and hsp65. Smooth, rough, or mixed colonies of both M. abscessus and M. massiliense isolates were observed. M. massiliense strains that were highly resistant to clarithromycin had a point mutation at the adenine at position 2058 (A(2058)) or 2059 (A(2059)) in the peptidyltransferase region of the 23S rRNA gene.

In-vitro antimycobacterial drug susceptibility testing of non-tubercular mycobacteria by tetrazolium microplate assay

BACKGROUND

Non-tubercular mycobacteria (NTM) has not been given due attention till the recent epidemic of HIV. This has led to increasing interest of health care workers in their biology, epidemiology and drug resistance. However, timely detection and drug susceptibility profiling of NTM isolates are always difficult in resource poor settings like India. Furthermore, no standardized methodology or guidelines are available to reproduce the results with clinical concordance.

OBJECTIVE

To find an alternative and rapid method for performing the drug susceptibility assay in a resource limited settings like India, we intended to evaluate the utility of Tetrazolium microplate assay (TEMA) in comparison with proportion method for reporting the drug resistance in clinical isolates of NTM.

METHODS

A total of fifty-five NTM isolates were tested for susceptibility against Streptomycin, Rifampicin, Ethambutol, Ciprofloxacin, Ofloxacin, Azithromycin, and Clarithromycin by TEMA and the results were compared with agar proportion method (APM).

RESULTS

Of the 55 isolates, 23 (41.8%) were sensitive to all the drugs and the remaining 32 (58.2%) were resistant to at least one drug. TEMA had very good concordance with APM except with minor discrepancies. Susceptibility results were obtained in the median of 5 to 9 days by TEMA. The NTM isolates were highly sensitive against Ofloxacin (98.18% sensitive) and Ciprofloxacin (90.09% sensitive). M. mucogenicum was sensitive only to Clarithromycin and resistant to all the other drugs tested. The concordance between TEMA and APM ranged between 96.4 - 100%.

CONCLUSION

Tetrazolium Microplate Assay is a rapid and highly reproducible method. However, it must be performed only in tertiary level Mycobacteriology laboratories with proper bio-safety conditions.

Association between 16S-23S internal transcribed spacer sequence groups of Mycobacterium avium complex and pulmonary disease

Organisms within the Mycobacterium avium complex (MAC) may have differential virulence. We compared 33 subjects with MAC pulmonary disease to 75 subjects with a single positive culture without disease. M. avium isolates were significantly more likely to be associated with MAC pulmonary disease (odds ratio = 5.14, 95% confidence interval = 1.25 to 22.73) than M. intracellulare.

Surgical treatment of pulmonary diseases due to nontuberculous mycobacteria

Although the treatment of pulmonary diseases due to nontuberculous mycobacteria (NTM) requires the long-term use of antibiotics in combination, the treatment success rates are unsatisfactory. We evaluated the clinical characteristics and surgical outcomes of 23 patients with NTM lung diseases who had underwent pulmonary resection. The median age of the patients was 45 yr. Of the 23 patients, 10 had Mycobacterium avium-intracellulare complex infection, 12 had M. abscessus infection, and one had M. xenopi infection. The indications for surgery were antibiotic therapy failure (n=11), remnant cavitary lesion with high probability of relapse (n=8), and massive hemoptysis (n=4). The most common procedure was lobectomy (48%). Postoperative complications occurred in eight patients (35%), including postoperative pneumonia (n=3) and late bronchopleural fistula (n=2). Negative sputum culture conversion was achieved and maintained in all except two mortalities. Although it is associated with a relatively high complication rate, patients with NTM lung disease whose disease is localized to one lung and who can tolerate resectional surgery might be considered for surgery, if there has been poor response to drug therapy or if the patients develop significant disease-related complications such as hemoptysis.