Molecular Basis of Resistance to First-Line Drugs of Mycobacterium tuberculosis/canettii Strains in Greece

The aim of this study was to determine the rate and the mutations of genes involved to the first-line antituberculous drugs' resistance of M. tuberculosis/canettii isolated in Central Greece from 2010 to 2019. During the study period, the rate of resistance to isoniazid, rifampicin, ethambutol, and pyrazinamide was 5.4%, 0.4%, 1.1%, and 1.1%, respectively. All phenotypically resistant isolates (14 to isoniazid, 3 to ethambutol, 3 to pyrazinamide, and 1 to rifampicin) and 17 susceptible isolates (control group) were tested for the presence of mutations/alterations/polymorphisms by PCR followed by sequencing analysis. The molecular typing of isolates was based on multispacer sequence typing. Despite the phenotypic resistance, mutations were detected in 13 of 21 isolates (11 isoniazid resistant, 1 rifampicin, and 1 pyrazinamide resistant). Four isoniazid-resistant strains carried the most common mutations S315T and C-15T, whereas the remaining seven isolates carried either less known (E399, A162, W477STOP, S94A, G-48A, C-54T, C-17T, L203, A196, S124, and K367) or novel (D74N, G691S, Ains-85, and D171G); none of the susceptible strains was found to be positive for any novel mutation. The two single rifampicin- and pyrazinamide-resistant strains carried the known mutations S450L (also referred as S531L) and L182W, respectively. The presence of uncommon or novel mutations conferring resistance to isoniazid (INH) creates a diagnostic problem in the routine microbiological laboratory, since commercial methods are focused on the detection of the most common mechanisms of resistance (S315T, C-15T, A-16G, T-8C, and T-8A), therefore, fail to detect such strains. The regional differences in the frequencies of mutations associated with resistance to the first-line drugs provide hints for the development of better molecular-based diagnostic tests.

Evaluating a 24-year tuberculosis screening in first-grade elementary schoolers in a low-burden area

AIM

Early diagnosis of tuberculosis infection can significantly contribute to the control of the disease. The aim of the present study was to describe the tuberculin skin test (TST) trends over a 24-year period (1990-2013) and explore the value of universal tuberculosis screening in a low-burden area.

METHODS

All first graders that underwent TST during the 24-year study period (1990-2013) on the island of Crete, Greece, were retrospectively included in the study.

RESULTS

A total of 82 402 children (92.3% of Greek nationality; 51.0% male) underwent TST, of whom 335 (0.41%, 95% CI 0.37-0.46) were found to have positive TST while 0.27% of the study population had a TST between 5 and 9 mm. The tuberculin index declined significantly between 1990-1994 and 2010-2013 (0.67 vs 0.26; RR 2.73, 95% CI 1.82-4.09; p < 0.0001). Positive TST result was significantly higher in the immigrant than the native group (0.66% vs 0.24%; RR 3.76 95%, CI 2.89-4.84; p < 0.0001). In the last study years, 386 children (488 native; 153 immigrant) should be tested for one to be found TST positive.

CONCLUSION

Our findings question the massive tuberculin testing in low-burden areas and point to selective screening of high-risk groups.

A review of eleven cases of tuberculosis presenting as sternal wound abscess after open heart surgery

BACKGROUND

Sternal wound infection with Mycobacterium tuberculosis is an uncommon yet highly challenging disease that can be quite insidious with various presentations. We hereby provide a review of 10 cases in current literature and describe an additional case which illustrates the difficulties associated with diagnosis.

METHODS

We used PubMed and Google search engine to search the literature for all published papers reporting on cases of sternal M. tuberculosis infections post open-heart surgeries.

RESULTS

A total of 11 cases were presented, including a case of our own. The majority were males and were exposed to endemic areas. The average age was 59.6 ± 15.5 years. Coronary artery bypass surgery accounted for 73% of procedures and the average time to symptoms onset was 12.2 ± 16.6 months. Diabetes was the most reported non-cardiac comorbidity. Presenting symptoms varied and only 5 patients had other organs involved. Blood tests and radiographic studies were neither sensitive nor specific. M. tuberculosis culture on debrided tissues was the most sensitive test but often forgotten initially. Diagnostic delay was seen in almost all cases, often leading to unnecessary courses of antibiotics and aggressive surgical interventions. Finally, all patients responded well to anti-tuberculosis treatment, with reported treatment duration ranging from 9 to 12 months.

CONCLUSION

M. tuberculosis infection of the sternum should be suspected in late-onset sternal wound infections post open-heart surgery especially when the course is chronic and indolent.

Combination of commercially available molecular assays and culture based methods in diagnosis of tuberculosis and drug resistant tuberculosis

Early diagnosis of tuberculosis is of major clinical importance. Among 4733 clinical specimens collected from 3363 patients and subjected to Ziehl–Neelsen microscopy, 4109 were inoculated onto Löwenstein–Jensen slants and 3139 in Bactec/9000MB. Polymerase Chain Reaction (PCR) was performed in 3139 specimens, whereas, a genotypic assay was directly applied in 93 Mycobacterium tuberculosis complex PCR-positive for isoniazid and rifampicin resistance detection specimens (GenoType MTBDRplus). Recovered M. tuberculosis isolates (64) as well as, 21 more sent from Regional Hospitals were tested for antimycobacterial resistance with a phenotypic (manual MGIT-SIRE) and a genotypic assay (GenoType MTBDRplus). PCR in the clinical specimens showed excellent specificity (97.4%) and accuracy (96.8%), good sensitivity (70.4%), but low positive predictive value (40.3%). MGIT-SIRE performed to M. tuberculosis did not confer a reliable result in 16 isolates. Of the remaining 69 isolates, 15 were resistant to streptomycin, seven to isoniazid, seven to ethambutol and five to rifampicin. GenoType MTBDRplus correctly detected isoniazid (seven) and rifampicin-resistant M. tuberculosis strains (five), showing an excellent performance overall (100%). Susceptibility results by the molecular assay applied directly to clinical specimens were identical to those obtained from recovered isolates of the corresponding patients. Combining molecular and conventional methods greatly contribute to early diagnosis and accurate susceptibility testing of tuberculosis.

The changing epidemiology of tuberculosis in a Spanish tertiary hospital (1995-2013)

Important epidemiological changes and improvement of new diagnostic approaches, mainly molecular tools, might have impacted the management and outcome of tuberculosis (TB) in the last years in industrialized countries. In order to describe the epidemiological trends, and changes in clinical, diagnostic, and therapeutic aspects in patients with TB, an observational study was performed in a tertiary hospital in Western Europe (Madrid, Spain).All adult patients (>16 years) with a diagnosis of TB in the period 1995 to 2013 were included in the study.TB was diagnosed in 1284 patients, including 304 (24%) foreign-born and 298 (23.2%) human immunodeficiency virus (HIV)-infected patients. The proportion of foreign-born patients increased significantly, from 7.4% (1995) to 40.3% (2013), P < .001, while the proportion of patients with HIV infection decreased (from 41% to 15%, P < .001). Extrapulmonary locations of TB increased (from 23.9% to 37.1%, P < .001), although the miliary forms were less frequent (from 16% to 5.6%, P < .001). Pulmonary involvement remained constant during the period of study (from 50% to 46%, P = .18). The yield of microbiological diagnostic methods in different clinical specimens has remained very similar. Only molecular techniques have improved the diagnosis in respiratory, urinary, and peritoneal samples. The global cure rate was 64.8% and mortality rate was 9.1% (6.5% directly attributable to TB). Mortality has decreased significantly during the years of study (from 11% to 2%, P < .001).There has been a significant decline in the number of patients with TB. Changes in HIV coinfection and immigration have conditioned other epidemiological and clinical aspects of the disease, including the clinical presentation, treatment response, and mortality. Only the use of molecular tests has provided an improvement in the diagnosis of pulmonary and extrapulmonary TB.

The impact of immunosuppressive therapy on QuantiFERON and tuberculin skin test for screening of latent tuberculosis in patients with inflammatory bowel disease scheduled for anti-TNF therapy

OBJECTIVE

Patients with inflammatory bowel disease (IBD) should be routinely screened for latent tuberculosis (LTB) before starting anti-TNF therapy in order to prevent reactivation of LTB. Besides tuberculin skin test (TST), QuantiFERON-TB Gold In-Tube (QFT-G-IT) has gained wide acceptance as a screening strategy for LTB in IBD, although it may be negatively influenced by the prior use of immunomodulators (IMM) such as azathioprine or methotrexate. This study aimed to assess the impact of IMM on the TST and the QFT-G-IT for LTB screening in IBD patients scheduled for anti-TNF therapy.

MATERIAL AND METHODS

This observational, prospective, single-center study included consecutive IBD patients scheduled for anti-TNF therapy undergoing on the same day both TST and QFT-G-IT for screening of LTB, between 2008 and 2010. Patients with a prior history of known or suspicious (L)TB receiving (prophylactic) anti-TB therapy were excluded.

RESULTS

Seventy-five patients were finally included; 28 were treated with thiopurines (IMM group), while 47 (control group) received either 5-aminosalicylic acid (n = 41) or no therapy (newly diagnosed patients, n = 6). Overall, TST and QFT-G-IT were positive in 14 (18.7%) and 16 (21.3%) patients, respectively. There was no statistically significant difference between the two groups regarding the TST (p = 0.761) and QFT-G-IT (0.572) positivity. The overall concordance between the two tests was moderate (kappa = 0.584), being substantial in the IMM group (kappa = 0.700) and moderate in the control group (kappa = 0.498).

CONCLUSION

These preliminary results suggest that IMM may not have a significant impact on either QFT-G-IT or TST, although larger, prospective studies are certainly warranted.

Drug resistance among tuberculosis cases in the European Union and European Economic Area, 2007 to 2012

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Drug-resistant tuberculosis in two children in Greece: report of the first extensively drug-resistant case

Extensively drug-resistant (XDR) tuberculosis (TB) represents a serious and growing problem in both endemic and non-endemic countries. We describe a 2.5-year-old girl with XDR-pulmonary TB and an 18-month-old boy with pre-XDR-central nervous system TB. Patients received individualized treatment with second-line anti-TB agents based on genotypic and phenotypic drug susceptibility testing results. Both children achieved culture conversion 3 months and 1 month after treatment initiation, respectively. The child with XDR-pulmonary TB showed evidence of cure while treatment adverse events were managed without treatment interruption. The child with pre-XDR-central nervous system TB after 6-month hospitalization with multiple infectious complications had a dismal end due to hepatic insufficiency possibly related to anti-TB treatment. This is the first report of children with pre-XDR and XDR TB in Greece, emphasizing the public health dimensions and management complexity of XDR TB.

Evaluation of tuberculosis underreporting in Greece through comparison with anti-tuberculosis drug consumption

Surveillance is an integral part of tuberculosis (TB) control. Greece has a low TB notification rate, but there are doubts about underreporting. Examining anti-TB drug consumption is a way to validate the results of surveillance and estimate TB burden in the country. We used surveillance data from 2004 to 2008 to calculate the average prescribed treatment duration with the first-line anti-TB drugs isoniazid, rifampicin, ethambutol and pyrazinamide. We then obtained the best available data on consumption of these drugs, and calculated the number of treated cases to which these quantities correspond. We thus estimated underreporting at around 80% (77-81%), and annual TB incidence at about 30 cases per 100,000 population, five times over the notification rate. Underreporting was found to be constant over the study period, while incidence followed a decreasing trend. In addition we estimated that one person receives chemoprophylaxis for latent tuberculosis infection (LTBI) for every three TB cases. These results indicate the need for a comprehensive plan to improve TB surveillance and TB contact tracing in Greece, especially in light of the economic crisis affecting the country since 2009.