[Investigation of extensive drug resistance in multidrug resistance tuberculosis isolates]. / Çok Ilaca Dirençli Tüberküloz Izolatlarinda Yaygin Ilaç Direncinin Arastirilmasi

Increasing number of drug resistant tuberculosis (TB) cases, observed in recent years, is an important public health problem. Extensively drug resistant TB (XDR-TB) is the development of resistance against any fluoroquinolones and at least one of the injectable second line anti-TB drugs in addition to resistance against isoniazide and rifampicin which are the first line anti-TB drugs [definition of multidrug resistant TB (MDR-TB)]. Anti-TB therapy failed with first-line anti-TB drugs due to MDR-TB cases is being planned according to second-line anti-TB drug susceptibility test results if available and if not, standart treatment protocols are used. Although it is recommended that individual anti-TB therapy should be designed according to the isolate's susceptibility test results, standart therapeutic protocols are always needed since second-line anti-TB drug susceptibility testing generally could not be performed in developing countries like Turkey. For this reason, nationwide and regional surveillance studies to determine the resistance patterns are always needed to make decisions about the standard therapy algorithms. In this study, it was aimed to investigate the presence of extensive drug resistance among 81 MDR-TB isolates obtained from various health care facilities from Istanbul, Izmir and Manisa and to determine the XDR-TB incidence in Marmara and Aegean regions. Furthermore, we aimed to provide epidemiological data to clinicians to support their choice of second-line anti-TB drugs for MDR-TB infections. Susceptibility testing of isolates for the first and the second-line anti-TB drugs were performed by using modified Middlebrook 7H9 broth in fluorometric BACTEC MGIT 960 system (Becton Dickinson, USA). Eighty-one MDR-TB isolates included in this study were isolated from 43 (53.1%) patients residing in Istanbul, 26 (32.1%) in Izmir and 12 (14.8%) in Manisa provinces. We could not find any isolate consistent with XDR-TB definition in this study. Second-line drug resistance rates of MDR-TB isolates to amikacin and kanamycin were 1.2%, ofloxacin and levofloxacin were 2.5%, capreomycin was 14.8%, ethionamide was 37% whereas linezolid resistance was not detected. Statistically significant correlation was detected between resistance rates of these antibiotic pairs; levofloxacin-ofloxacin (p< 0.01), amikacin-kanamycin (p= 0.01) and streptomycin-ethionamide (p= 0.04). In our study, extensive drug resistance was not encountered in any MDR-TB isolates while high resistance rates was observed against ethionamide and capreomycin. It can be concluded that parenteral aminoglycosides amikasin and kanamycin, fluoroquinolones and linezolid seemed to be reliable anti-TB agents in MDR-TB treatment, however, further larger scale studies are needed.

Demographic and microbial characteristics and drug resistance of childhood tuberculosis in Istanbul: analysis of 1,541 cases.

INTRODUCTION: Although tuberculosis (TB) is frequently seen in Turkey, there are limited studies on childhood TB. We aimed to describe clinical and laboratory findings, including drug resistance, of children with TB in Istanbul, Turkey. METHODOLOGY: The study included all children aged 0-14 years who were registered in public dispensaries between 2006 and 2010. RESULTS: The study included 1,541 cases. Forty-four percent (n = 763) of the patients were male with a mean age of 8.86 ± 4.19 years. Fifty-five percent of the patients had pulmonary TB, 39% had extrapulmonary TB, and 6% had both pulmonary and extrapulmonary TB. The most common extrapulmonary involvement sites were the pleura (n = 193), lymph nodes (n = 247), and central nervous system (n = 41). Forty-one percent of the patients were evaluated microbiologically and 35% of them were positive. For the total study group, 14% of them were positive. A drug susceptibility test was performed on 108 patients. Drug resistance to at least one drug was detected in 16% (n = 17), to isoniazid in 15% (n = 16), streptomycin in 12% (n = 12), rifampicin in 9% (n = 10), ethambutol in 7% (n = 8), and multi-drug resistance in 8% (n = 9) of patients. CONCLUSIONS: This is the largest analysis on demographic features and drug resistance of childhood TB in Turkey. In Turkey, the rate of microbiological diagnosis is low, similar to rates worldwide. More microbiological studies and drug resistance tests should be done and annual changes should be followed with multi-center studies.

Low prevalence of hepatitis C virus infection in hemodialysis units: effect of isolation?

Hepatitis C virus (HCV) infection has recently become the major cause of chronic liver disease among patients on chronic hemodialysis. The use of erythropoietin for treatment of anemia has reduced the number of blood transfusions, but the frequency of HCV infection has not declined in hemodialysis units. The exact mode of transmission of HCV within dialysis units is as yet incompletely defined, but there is evidence to support nosocomial transmission by sharing dialysis machines in the hemodialysis unit. We performed a study to estimate the prevalence of HCV infection in our hemodialysis unit and to evaluate the effect of patient isolation and use of devoted dialysis machines for HCV-positive patients on the spread of HCV infection. A total of 168 patients on chronic hemodialysis (92 males and 76 females; mean age 54 +/- 12) were screened for HCV-antibodies (HCV-Ab) before their admission to the dialysis unit. Seropositive patients were isolated and confined to dedicated dialysis machines. Aminotransferases were measured monthly and HCV-Ab screening was performed second or third generation ELISA test every two months. Seropositive patients were tested by the PCR for the detection of HCV-RNA. Between March 1992 and August 2000, eight of 168 patients showed seroconversion. Seropositive patients were also found HCV-RNA positive. Four of these patients have become seropositive after they had undergone hemodialysis in other dialysis centers on holiday, two patients had received blood transfusions within the six months preceding seroconversion. The prevalence of HCV positivity in our hemodialysis unit is 4.7%. The low prevalence of HCV infection of our unit suggests that patient isolation and use of dedicated dialysis machines for seropositive patients decrease the transmission of HCV infection in hemodialysis units.