Real-world treatment patterns in patients with nontuberculous mycobacterial lung disease in the Netherlands based on medication dispensing data

PURPOSE

Real-world data on antibiotic management of nontuberculous mycobacterial lung disease (NTM-LD) is limited for many countries. This study aimed to evaluate real-world treatment practices of NTM-LD in the Netherlands using medication dispensing data.

METHODS

A retrospective longitudinal real-world study was conducted using IQVIA's Dutch pharmaceutical dispensing database. The data are collected monthly and include approximately 70% of all outpatient prescriptions in the Netherlands. Patients initiated on specific NTM-LD treatment regimens between October 2015 and September 2020 were included. The main areas of investigation were initial treatment regimens, persistence on treatment, treatment switching, treatment compliance in terms of medication possession rate (MPR) and restarts of treatment.

RESULTS

The database included 465 unique patients initiated on triple- or dual-drug regimens for the treatment of NTM-LD. Treatment switches were common and occurred approximately 1.6 per quarter throughout the treatment period. The average MPR of patients initiated on triple-drug therapy was 90%. The median time on therapy for these patients was 119 days; after six months and one year, 47% and 20% of the patients, respectively, were still on antibiotic therapy. Of 187 patients initiated on triple-drug therapy, 33 (18%) patients restarted antibiotic therapy after the initial treatment had been stopped.

CONCLUSION

When on therapy, patients were compliant with the NTM-LD treatment; however, many patients stopped their therapy prematurely, treatment switches often occurred, and part of patients had to restart their therapy after a longer treatment gap. NTM-LD management should be improved through greater guideline adherence and appropriate involvement of expert centers.

International Society of Cardiovascular Infectious Diseases Guidelines for the Diagnosis, Treatment and Prevention of Disseminated Mycobacterium chimaera Infection Following Cardiac Surgery with Cardiopulmonary Bypass

Mycobacterial infection-related morbidity and mortality in patients following cardiopulmonary bypass surgery is high and there is a growing need for a consensus-based expert opinion to provide international guidance for diagnosing, preventing and treating in these patients. In this document the International Society for Cardiovascular Infectious Diseases (ISCVID) covers aspects of prevention (field of hospital epidemiology), clinical management (infectious disease specialists, cardiac surgeons, ophthalmologists, others), laboratory diagnostics (microbiologists, molecular diagnostics), device management (perfusionists, cardiac surgeons) and public health aspects.

Microbiological criteria in non-tuberculous mycobacteria pulmonary disease: a tool for diagnosis and epidemiology

SETTING

The value of microbiological criteria in diagnosing non-tuberculous mycobacteria pulmonary disease (NTM-PD) and monitoring its epidemiology is unknown.

OBJECTIVES

To correlate the rate of NTM-PD based on microbiological criteria (American Thoracic Society/Infectious Diseases Society of America [ATS/IDSA] or stricter microbiological criteria) compared with the full ATS/IDSA criteria, to assess the positive predictive value (PPV) of different microbiological criteria in predicting NTM-PD, and to evaluate the clinical relevance of different NTM species.

DESIGN

Retrospective study of all patients with pulmonary NTM isolates in Croatia during an 8-year period. NTM species were divided into low, intermediate and high clinical relevance groups for additional analyses.

RESULTS

Good correlation between both microbiological and full ATS/IDSA criteria was observed. The PPV of stricter and ATS/IDSA microbiological criteria was respectively 93.3% and 59.8%. The usefulness of microbiological criteria varied between groups. ATS/IDSA microbiological criteria had a PPV of 89.8% in the high relevance group, while in the intermediate relevance group, the PPV of stricter and ATS/IDSA microbiological criteria was respectively 94.3% and 63.4%.

CONCLUSIONS

Microbiological criteria are useful in detecting NTM-PD, allowing laboratory-based monitoring. Stricter criteria should be used for species of low clinical relevance, and less stringent criteria for species of high relevance in the local setting.

How to: identify non-tuberculous Mycobacterium species using MALDI-TOF mass spectrometry

BACKGROUND

The implementation of MALDI-TOF MS for microorganism identification has changed the routine of the microbiology laboratories as we knew it. Most microorganisms can now be reliably identified within minutes using this inexpensive, user-friendly methodology. However, its application in the identification of mycobacteria isolates has been hampered by the structure of their cell wall. Improvements in the sample processing method and in the available database have proved key factors for the rapid and reliable identification of non-tuberculous mycobacteria isolates using MALDI-TOF MS.

AIMS

The main objective is to provide information about the proceedings for the identification of non-tuberculous isolates using MALDI-TOF MS and to review different sample processing methods, available databases, and the interpretation of the results.

SOURCES

Results from relevant studies on the use of the available MALDI-TOF MS instruments, the implementation of innovative sample processing methods, or the implementation of improved databases are discussed.

CONTENT

Insight about the methodology required for reliable identification of non-tuberculous mycobacteria and its implementation in the microbiology laboratory routine is provided.

IMPLICATIONS

Microbiology laboratories where MALDI-TOF MS is available can benefit from its capacity to identify most clinically interesting non-tuberculous mycobacteria in a rapid, reliable, and inexpensive manner.

First case of Mycobacterium heckeshornense cavitary lung disease in the Latin America and Caribbean region

A case of cavitary pulmonary disease caused by Mycobacterium heckeshornense in Uruguay is described. This is the first case reported in the Latin America and Caribbean region, showing that this species is a worldwide opportunistic human pathogen.

Second worldwide proficiency study on variable number of tandem repeats typing of Mycobacterium tuberculosis complex

BACKGROUND

The quality of variable number of tandem repeats (VNTR) typing of Mycobacterium tuberculosis was first investigated in 2009 in 37 laboratories worldwide. The results revealed an inter- and intra-laboratory reproducibility of respectively 60% and 72%. These data spurred an improvement in laboratory-specific assays and global standardisation of VNTR typing.

OBJECTIVE

To measure the effects of the technical improvements and increased standardisation, a test panel consisting of 30 M. tuberculosis complex DNA samples was distributed for VNTR typing in 41 participating laboratories from 36 countries.

RESULTS

The inter- and intra-laboratory reproducibility increased overall to respectively 78% and 88%. The 33 laboratories that participated in both the first and second proficiency studies improved their inter- and intra-laboratory reproducibility from 62% and 72% to respectively 79% and 88%. The largest improvement in reproducibility was detected in 10 laboratories that use an in-house polymerase chain reaction technique and perform amplicon sizing using gel electrophoresis. Detailed error analysis revealed a reduction in the number of systematic errors, sample exchange events and non-amplifiable loci.

CONCLUSION

This second worldwide proficiency study indicates a substantial increase in the reproducibility of VNTR typing of M. tuberculosis. This will contribute to a more meaningful interpretation of molecular epidemiological and phylogenetic studies on the M. tuberculosis complex.

Rapid diagnosis of pyrazinamide-resistant multidrug-resistant tuberculosis using a molecular-based diagnostic algorithm

There is an urgent need for rapid and accurate diagnosis of pyrazinamide-resistant multidrug-resistant tuberculosis (MDR-TB). No diagnostic algorithm has been validated in this population. We hypothesized that pncA sequencing added to rpoB mutation analysis can accurately identify patients with pyrazinamide-resistant MDR-TB. We identified from the Dutch national database (2007-11) patients with a positive Mycobacterium tuberculosis culture containing a mutation in the rpoB gene. In these cases, we prospectively sequenced the pncA gene. Results from the rpoB and pncA mutation analysis (pncA added to rpoB) were compared with phenotypic susceptibility testing results to rifampicin, isoniazid and pyrazinamide (reference standard) using the Mycobacterial Growth Indicator Tube 960 system. We included 83 clinical M. tuberculosis isolates containing rpoB mutations in the primary analysis. Rifampicin resistance was seen in 72 isolates (87%), isoniazid resistance in 73 isolates (88%) and MDR-TB in 65 isolates (78%). Phenotypic reference testing identified pyrazinamide-resistant MDR-TB in 31 isolates (48%). Sensitivity of pncA sequencing added to rpoB mutation analysis for detecting pyrazinamide-resistant MDR-TB was 96.8%, the specificity was 94.2%, the positive predictive value was 90.9%, the negative predictive value was 98.0%, the positive likelihood was 16.8 and the negative likelihood was 0.03. In conclusion, pyrazinamide-resistant MDR-TB can be accurately detected using pncA sequencing added to rpoB mutation analysis. We propose to include pncA sequencing in every isolate with an rpoB mutation, allowing for stratification of MDR-TB treatment according to pyrazinamide susceptibility.

Molecular surveillance of multi- and extensively drug-resistant tuberculosis transmission in the European Union from 2003 to 2011

The European Centre for Disease Prevention and Control (ECDC) initiated a project on the molecular surveillance of multi- and extensively drug-resistant tuberculosis (MDR-/XDR-TB) transmission in the European Union (EU) in the period from 2009 to 2011. In total, 2,092 variable number of tandem repeat (VNTR) patterns of MDR-/XDR-TB Mycobacterium tuberculosis isolates were collected, originating from 24 different countries in the period 2003 to 2011. Of the collected VNTR patterns, 45% (n=941) could be assigned to one of the 79 European multiple-country molecular fingerprint clusters and 50% of those (n=470) belonged to one extremely large cluster caused by Beijing strains of one genotype. We conclude that international transmission of MDR-/XDR-TB plays an important role in the EU, especially in the eastern part, and is significantly related to the spread of one strain or clone of the Beijing genotype. Implementation of international cluster investigation in EU countries should reveal underlying factors of transmission, and show how TB control can be improved regarding case finding, contact tracing, infection control and treatment in order to prevent further spread of MDR-/XDR-TB in the EU.

Early stationary phase culture supernatant accelerates growth of sputum cultures collected after initiation of anti-tuberculosis treatment

We investigated the effect of Mycobacterium tuberculosis culture supernatant added to sputum cultures collected during the first 8 weeks of anti-tuberculosis treatment. With ongoing treatment duration, time to culture positivity decreased significantly in supernatant-enriched cultures, possibly due to stimulation of dormant or slowly metabolizing M. tuberculosis cells.

Geographical distribution and clinical relevance of non-tuberculous mycobacteria in Croatia

SETTING

The clinical relevance of non-tuberculous mycobacteria (NTM) in Croatia is unknown.

OBJECTIVE

To estimate the isolation rate of NTM, record geographical differences and assess the burden of pulmonary NTM disease in Croatia.

DESIGN

Nationwide retrospective cohort study of all Croatian residents with NTM isolated by culture in the period from 2006 to 2010. Microbiological criteria of the American Thoracic Society were used to establish a laboratory-based case definition of possible and probable NTM disease.

RESULTS

Of 1187 individuals with pulmonary NTM isolates, 8.6% met the possible and 5.5% met the probable disease criteria. We estimated an annual incidence of probable pulmonary NTM disease of 0.23 per 100,000 population. This estimated annual incidence was 0.35/100,000 in the coastal region and 0.17/100,000 in the continental region. Species distribution differed between coastal and continental Croatia. NTM isolation frequency increased over the study period.

CONCLUSION

Geography plays an important role in NTM species distribution and possible disease. The overall burden of NTM pulmonary disease in Croatia is still low compared to that of tuberculosis, but it is higher in the coastal region compared to the continental region.

Mycobacterium genavense in the Netherlands: an opportunistic pathogen in HIV and non-HIV immunocompromised patients. An observational study in 14 cases

Mycobacterium genavense is an opportunistic non-tuberculous mycobacterium previously mostly associated with HIV-infected patients with CD4 counts below 100/μL. In this retrospective observational study of medical charts we studied all Dutch patients in whom M. genavense was detected between January 2002 and January 2010. Of the 14 patients identified, 13 (93%) showed clinically relevant M. genavense disease. All patients with M. genavense disease were severely immunocompromised, including HIV-infected patients, solid organ transplant recipients, those with chronic steroid use in combination with other immune modulating drugs, recipients of chemotherapy for non-Hodgkin lymphoma, and those with immunodeficiency syndromes. Two patients had non-disseminated pulmonary M. genavense disease. Of the 12 patients treated, eight (75%) showed a favourable outcome. Four patients died in this study, three despite treatment for M. genavense disease. We conclude that M. genavense is a clinically relevant pathogen in severely immunocompromised patients that causes predominantly disseminated disease with serious morbidity and mortality. M. genavense is increasingly seen among non-HIV immunocompromised patients.

Low-level rifampicin-resistant Mycobacterium tuberculosis strains raise a new therapeutic challenge

In an outbreak of multidrug-resistant tuberculosis, the outbreak strain had an Asp516Tyr rpoB gene mutation. Phenotypically, low-level rifampicin (RMP) resistance (minimum inhibitory concentration [MIC] 1-2 mg/l) was observed. Based on drug susceptibility test results, three patients were treated with 12-15 month rifabutin-based regimens and one with a 12-month RMP-based regimen. We retrospectively performed pharmacokinetic calculations to assess the potential for RMP treatment, from which we conclude that MICs for RMP up to 1 μg/ml may be safely overcome by applying 20 mg/kg RMP doses in treatment regimens.

Xpert MTB/RIF®, a novel automated polymerase chain reaction-based tool for the diagnosis of tuberculosis

There is an urgent need for new point of care tests for tuberculosis (TB). Xpert MTB/RIF® is a real-time polymerase chain reaction-based system that detects Mycobacterium tuberculosis DNA and rifampicin (RMP) resistance modulating mutations directly from clinical samples in 2 h. The sensitivity for detecting M. tuberculosis in culture-positive samples was 93.8% (60/64) and exceeded smear microscopy (40/64, 62.5%). The specificity for detecting M. tuberculosis was 92.0% (23/25) and for RMP resistance it was 100% (8/8). The test is simple to conduct and requires basic sputum handling facilities only. These characteristics render it a promising close-to-patient test for TB in various settings.

Re-analysis of 178 previously unidentifiable Mycobacterium isolates in the Netherlands in 1999-2007

Nontuberculous mycobacteria (NTM) that cannot be identified to the species level by reverse line blot hybridization assays and sequencing of the 16S rRNA gene comprise a challenge for reference laboratories. However, the number of 16S rRNA gene sequences added to online public databases is growing rapidly, as is the number of Mycobacterium species. Therefore, we re-analysed 178 Mycobacterium isolates with 53 previously unmatched 16S rRNA gene sequences, submitted to our national reference laboratory in 1999–2007. All sequences were again compared with the GenBank database sequences and the isolates were re-identified using two commercially available identification kits, targeting separate genetic loci. Ninety-three out of 178 isolates (52%) with 20 different 16S rRNA gene sequences could be assigned to validly published species. The two reverse line blot assays provided false identifications for three recently described species and 22 discrepancies were recorded in the identification results between the two reverse line blot assays. Identification by reverse line blot assays underestimates the genetic heterogeneity among NTM. This heterogeneity can be clinically relevant because particular sub-groupings of species can cause specific disease types. Therefore, sequence-based identification is preferable, at least at the reference laboratory level, although the exact targets needed for clinically useful results remain to be established. The number of NTM species in the environment is probably so high that unidentifiable clinical isolates should be given a separate species status only if this is clinically meaningful.

Multiple strains of Mycobacterium avium subspecies hominissuis infections associated with aborted fetuses and wasting in pigs

A herd of pigs being reared for breeding and fattening, in which there had been incidences of abortion and wasting, reduced growth rates and an increase in mortality for the past year, were tested for Mycobacterium infection by pathological examinations, skin test, serology and Mycobacterium culture. In one placenta, and also in the lung tissues of fetuses, Ziehl-Neelsen staining revealed acid-fast bacilli in combination with infiltrations of neutrophils, macrophages and multinucleated giant cells. Acid-fast bacilli were also found in the mesenteric lymph nodes, liver and/or spleen and jejunum of pigs with wasting and in slaughtered animals. The specimen cultures were identified as Mycobacterium avium subspecies hominissuis using IS1245-specific PCR and IS1245 restriction fragment length polymorphism (RFLP). IS1245 RFLP revealed that the herd was infected with multiple M avium subspecies hominissuis strains belonging to at least two different clades. It is suggested that this infection may have played a more important role in the economic losses of the pig farm than had been assumed previously.

Application of modern microbiological diagnostic methods for tuberculosis in Macha, Zambia

SETTING

Macha, Zambia.

OBJECTIVE

To assess the benefits of auramine-O staining fluorescence microscopy and Mycobacterial Growth Indicator Tube (MGIT) liquid culture with molecular identification in tuberculosis (TB) diagnostics.

DESIGN

One hundred patients suspected of TB were subjected to three sputum sample examinations applying Ziehl-Neelsen (ZN) and auramine-O staining and MGIT culture. Positive cultures were identified using the GenoType CM assay; cultures identified as Mycobacterium tuberculosis complex were the gold standard for a diagnosis of TB.

RESULTS

The 100 patients produced 271 sputum samples; of these, 30 patients had positive cultures. M. tuberculosis complex bacilli were isolated in 17 (56.7%) patients, non-tuberculous mycobacteria (NTM) in 11 (36.7%) and other acid-fast bacilli in two. Forty-eight samples (17.7%) were contaminated. Auramine-O detected 16 (57.1%) patients culture-positive for mycobacteria and 12 patients with culture-proven TB, vs. respectively 8 (28.6%, P = 0.008) and 7 (41.2%, P = 0.044) for ZN. Three of eight auramine-positive/ZN-negative patients were culture-positive for NTM only.

CONCLUSION

The auramine-O method significantly increases sensitivity, although the higher NTM detection rate implies that this does not in itself lead to a more accurate diagnosis of TB. MGIT culture is highly sensitive, although contamination rates were a drawback; the high frequency of NTM isolation warrants a robust identification method.

The changing pattern of clinical Mycobacterium avium isolation in the Netherlands

SETTING

National Mycobacteria Reference Laboratory, The Netherlands.

OBJECTIVE

To assess the role of factors other than laboratory improvements in the increasing frequency of isolation of non-tuberculous mycobacteria (NTM) in the Netherlands; laboratory improvements are often considered key factors in this increase.

DESIGN

Laboratory database study. All clinically isolated NTM referred to the national reference laboratory between January 2000 and January 2007 were retrieved from the laboratory database and categorised by species, patient age group and sample origin. Data were compared with national demographic data.

RESULTS

Clinical Mycobacterium avium isolates accounted for most of the increase in referred NTM. The number of respiratory M. avium samples in patients aged >40 years increased over time. This age group increased in size during the study. In this age group, the prevalence of chronic obstructive pulmonary disease (COPD) increased during the study period. M. avium isolation from lymph nodes in children remained stable, whereas extra-pulmonary M. avium isolation in the middle age group, including human immunodeficiency virus associated bloodstream isolates, decreased.

CONCLUSIONS

The increasing NTM notification in the Netherlands is unlikely to have been a result of laboratory improvements alone: the ageing population with an increasing prevalence of COPD is likely as important. Environmental characteristics may specifically favour M.avium.

Surgical treatment of non-tuberculous mycobacterial lung disease: strike in time

SETTING

The Netherlands.

OBJECTIVE

To describe our experiences with the adjunctive role and benefits of surgery for lung disease due to non-tuberculous mycobacteria (NTM), specifically addressing its indications and timing.

DESIGN

Retrospective medical file review of eight patients who underwent surgical treatment for NTM lung disease in the period January 2000 to January 2009, and review of the available literature.

RESULTS

Therapy-resistant cavitary NTM disease was the most frequent indication for surgery; two patients underwent pneumonectomy for an infected destroyed lung. Mycobacterium avium was the most common causative agent. Surgery resulted in culture conversion in seven patients; one patient died 2 months after pneumonectomy. No relapses have been noted in the other seven after an average of 19 months of follow-up.

CONCLUSIONS

Adjunctive surgical treatment for NTM lung disease yields encouraging results, similar to previously published case series. Careful patient selection, based on extent and type of disease as well as on cardiopulmonary fitness, is important. Potential benefits of surgery should be considered for every individual patient in whom NTM lung disease is diagnosed and re-evaluated after 6 months of treatment. Where possible, surgery should be pursued and conducted in a timely fashion.

Proposal to elevate Mycobacterium avium complex ITS sequevar MAC-Q to Mycobacterium vulneris sp. nov

The Mycobacterium avium complex (MAC) consists of four recognized species, Mycobacterium avium, Mycobacterium colombiense, Mycobacterium intracellulare and Mycobacterium chimaera, and a variety of other strains that may be members of undescribed taxa. We report on two isolates of a scotochromogenic, slowly growing, non-tuberculous Mycobacterium species within the M. avium complex from a lymph node and an infected wound after a dogbite of separate patients in The Netherlands. The extrapulmonary infections in immunocompetent patients suggested a high level of virulence. These isolates were characterized by a unique nucleotide sequence in the 16S rRNA gene, 99% similar to Mycobacterium colombiense, and the MAC-Q 16S-23S internal transcribed spacer (ITS) sequence. Sequence analyses of the hsp65 gene revealed 97% similarity to M. avium. The rpoB gene sequence was 98% similar to M. colombiense. Phenotypically, the scotochromogenicity, positive semi-quantitative catalase and heat-stable catalase tests, negative tellurite reductase and urease tests and susceptibility to hydroxylamine and oleic acid set these isolates apart from related species. High-performance liquid chromatography analysis of cell-wall mycolic acid content revealed a unique pattern, related to that of M. avium and M. colombiense. Together, these findings supported a separate species status within the Mycobacterium avium complex. We propose elevation of scotochromogenic M. avium complex strains sharing this 16S gene and MAC-Q ITS sequence to separate species status, for which the name Mycobacterium vulneris sp. nov. is proposed. The type strain is NLA000700772T (=DSM 45247T=CIP 109859T).

Clinical relevance of non-tuberculous mycobacteria isolated in the Nijmegen-Arnhem region, The Netherlands

BACKGROUND

The frequency of clinical isolation of non-tuberculous mycobacteria (NTM) in the Netherlands is increasing, but its clinical relevance is often uncertain.

OBJECTIVE

To assess the frequency and clinical relevance of isolation of NTM in four associated hospitals in a single region in the Netherlands.

METHODS

Medical files of all patients from whom NTM were isolated between January 1999 and January 2005 were reviewed retrospectively. Diagnostic criteria for non-tuberculous mycobacterial disease published by the American Thoracic Society (ATS) were used to determine clinical relevance.

RESULTS

232 patients were found, from whom NTM were isolated from the respiratory tract in 91% of cases. Patients were mostly white men, with an average age of 60 years and pre-existing pulmonary disease. Fifty-three of 212 patients (25%) with pulmonary isolates met the ATS diagnostic criteria for pulmonary NTM disease; this percentage differed by species. Most patients were treated with rifampicin, ethambutol and clarithromycin. Treatment outcome for pulmonary NTM disease was suboptimal but differed by species: overall, improvement was seen in 67% of treated patients, but in only 50% of those with pulmonary M avium disease. Lymphadenitis was the most common extrapulmonary disease type.

CONCLUSIONS

Twenty-five per cent of all patients with pulmonary NTM isolates met the ATS criteria. Clinical relevance differs by species. NTM isolation increases over time. Species distribution differs from that of neighbouring countries and the M avium complex isolates have traits different from those reported in the USA. Adherence to diagnostic and treatment guidelines can be improved.

Second-line drug resistance in multidrug-resistant tuberculosis cases of various origins in the Netherlands

SETTING

The Netherlands.

OBJECTIVE

To investigate the frequency of resistance to second-line drugs among multidrug-resistant tuberculosis (MDR-TB) cases and its correlation with patients' geographic origin.

DESIGN

Retrospective laboratory database study of multidrug-resistant Mycobacterium tuberculosis complex strains isolated in the Netherlands between January 1993 and October 2007.

RESULTS

We found 153 patients with MDR-TB, of whom 18 (12%) were native Dutch. Complete second-line drug susceptibility testing was performed for 131 MDR-TB patients. Resistance to second-line drugs was noted in primary samples of 28 (21%) MDR-TB patients. Resistance to a single second-line drug was most frequent (24/28 [86%]; 9 to prothionamide [PTH], 6 to para-aminosalicylic acid, 4 to amikacin [AMK], 4 to ciprofloxacin and 1 to cycloserine). Four MDR-TB patients had strains resistant to multiple second-line drugs; two were extensively drug-resistant M. bovis. In MDR-TB patients of European and Central Asian origin, resistance to second-line drugs was most frequent and involved the widest range of drugs. PTH resistance was frequent among African and American MDR-TB patients, while AMK resistance was frequent among South-East Asians.

CONCLUSION

Resistance to second-line drugs is infrequent among MDR-TB patients in the Netherlands. Most second-line drug resistance is recorded among immigrants, with substantial differences in second-line drug resistance in MDR-TB patients originating from different geographical areas.

Mechanisms of heteroresistance to isoniazid and rifampin of Mycobacterium tuberculosis in Tashkent, Uzbekistan

Heteroresistance of Mycobacterium tuberculosis (MTB) is defined as the coexistence of susceptible and resistant organisms to anti-tuberculosis (TB) drugs in the same patient. Heteroresistance of MTB is considered a preliminary stage to full resistance. To date, no mechanism causing heteroresistance of MTB has been proven. Clinical specimens and cultures from 35 TB patients from Tashkent, Uzbekistan, were analysed using the Genotype MTBDR assay (Hain Lifescience, Nehren, Germany), which is designed to detect genetic mutations associated with resistance to rifampin and isoniazid. Cases of heteroresistance were further subjected to genotyping using mycobacterial interspersed repetitive unit-variable-number tandem repeat typing, spoligotyping and IS6110 fingerprinting. Heteroresistance to rifampin and/or isoniazid was found in seven cases (20%). In five of them, heteroresistance was caused by two different strains and in two by a single strain of the Beijing genotype. The latter cases had a history of relapse of their TB. For the first time, two different mechanisms of heteroresistance in tuberculosis have been proven using a stepwise molecular-biological approach: 1) superinfection with two different strains, which is of interest for clinical infection control practitioners; and 2) splitting of a single strain into susceptible and resistant organisms. The latter mechanism is most likely to be related to poor treatment quality and could serve as a quality marker for tuberculosis therapy programmes in the future.

The rising incidence and clinical relevance of Mycobacterium malmoense: a review of the literature

The incidence of Mycobacterium malmoense infections compared to other non-tuberculous mycobacteria (NTM) has increased since 1980, especially in northern Europe. Based on various epidemiological and clinical reports outside northern Europe, there is a wide distribution of these infections. Infections with M. malmoense cause pulmonary disease comparable with tuberculosis (TB). The main extra-pulmonary disease type is paediatric cervical lymphadenitis. M. malmoense isolates are clinically significant in about 70-80% of patients. Like other NTM infections, M. malmoense is often found in patients with chronic obstructive pulmonary disease (COPD) and may cause serious morbidity and mortality when inadequately treated. The best treatment consists of a 2-year regimen with rifampicin and ethambutol. The literature on infections with M. malmoense is reviewed with respect to epidemiology, clinical presentation, treatment and outcome.

[Characteristics and treatment of tuberculosis patients in Dekkerswald, 2000-2005]

OBJECTIVE

To describe the patient population in Dekkerswald, Nijmegen, one of two tuberculosis (TB) centres in The Netherlands.

DESIGN

Descriptive, retrospective study.

METHOD

Examination of medical records for all TB patients hospitalised between 2000 and 2005, including demographic, social, clinical and follow-up data.

RESULTS

Data from 166 patients were analysed. Tertiary referrals accounted for 98% of all hospitalisations. Most patients (68%) were referred for clinical reasons, and 32% were referred for social reasons. Drug resistance was encountered in 23% of patients; 9% had multidrug-resistant TB. Ten percent of patients were seropositive for HIV. Toxicity and side-effects of treatment often led to changes in treatment (40%). Patients had pulmonary TB (59%), extrapulmonary TB (23%) or both (17%). Overall, 141 patients (85%) completed treatment. The TB-related mortality rate was 5%.

CONCLUSION

In Dekkerswald, there is a selected patient population that is characterised by drug-resistance, comorbidity, side-effects, extrapulmonary disease and social issues. Due to the low prevalence of TB in The Netherlands, knowledge and experience regarding complex types of TB are limited. Centralisation of patient care is important to preserve and optimise this expertise.

Patterns of cytokines, plasma endotoxin, plasminogen activator inhibitor, and acute-phase proteins during the treatment of severe sepsis in humans

OBJECTIVE

To study the patterns of plasma concentrations of endotoxin, tumor necrosis factor-alpha (TNF), interleukin-6 (IL-6), plasminogen activator inhibitor-1, C-reactive protein, and serum amyloid A during the treatment of human sepsis.

DESIGN

A prospective case series study.

SETTING

ICU of the Department of Internal Medicine, University Hospital Groningen, The Netherlands.

PATIENTS

Twenty consecutive patients (11 female, 9 male, mean age 67 yrs) with clinically defined sepsis. Eighteen patients were admitted from the outpatient emergency ward; two patients were already inpatients. The control group (n = 7) comprised patients with nonseptic shock.

MEASUREMENTS AND MAIN RESULTS

Ten (50%) septic patients had detectable endotoxemia (greater than 5 (ng/L). TNF concentrations on admission were increased in 94% of the septic patients, whereas IL-6 and plasminogen activator inhibitor plasma concentrations were increased in all septic patients. The septic group showed significantly (p less than .05) higher concentrations of TNF, IL-6, plasminogen activator inhibitor-1, C-reactive protein, and serum amyloid A compared with the nonseptic patients. In the septic group, we found a correlation of both IL-6 and plasminogen activator inhibitor concentrations with severity of illness (r2 = .33, p less than .05; r2 = .22, p less than .05, respectively). After the start of antibiotic treatment, high concentrations of TNF and plasminogen activator inhibitor persisted in the nonsurvivors in contrast to decreasing concentrations in most of the survivors. After an initial increase in seven patients, IL-6 concentrations decreased in all septic patients and also in nonsurvivors.

CONCLUSIONS

This study confirms previous findings that: a) TNF is a major mediator involved in the pathogenesis of septic shock; b) plasminogen activator inhibitor activity is significantly increased in septic patients and might be involved in the pathogenesis of disseminated intravascular coagulation associated with sepsis; and c) IL-6 is involved in the pathophysiology of septic shock, although further studies are needed to determine whether IL-6 is directly involved in mediating the lethal complications of septic shock or whether it should be considered an "alarm hormone" that reflects endothelial cell injury. Our findings also suggest that the concentrations and trends of these mediators during treatment are valuable for monitoring septic patients.

Bone lesions mimicking disseminated malignancy after remission of thoracic sarcoidosis

A case of chronic sarcoidosis is presented with extensive involvement of the central skeleton, mimicking disseminated malignancy. The skeletal lesions occurred several years after spontaneous remission of thoracic sarcoidosis and were not accompanied by recurrence of active thoracic disease. Bone lesions in sarcoidosis are associated with lesions of skin and nasal mucosa.