Reduced Chance of Hearing Loss Associated with Therapeutic Drug Monitoring of Aminoglycosides in the Treatment of Multidrug-Resistant Tuberculosis.

Hearing loss and nephrotoxicity are associated with prolonged treatment duration and higher dosage of amikacin and kanamycin. In our tuberculosis center, we used therapeutic drug monitoring (TDM) targeting preset pharmacokinetic/pharmacodynamic (PK/PD) surrogate endpoints in an attempt to maintain efficacy while preventing (oto)toxicity. To evaluate this strategy, we retrospectively evaluated medical charts of tuberculosis (TB) patients treated with amikacin or kanamycin in the period from 2000 to 2012. Patients with culture-confirmed multiresistant or extensively drug-resistant tuberculosis (MDR/XDR-TB) receiving amikacin or kanamycin as part of their TB treatment for at least 3 days were eligible for inclusion in this retrospective study. Clinical data, including maximum concentration (Cmax), Cmin, and audiometry data, were extracted from the patients' medical charts. A total of 80 patients met the inclusion criteria. The mean weighted Cmax/MIC ratios obtained from 57 patients were 31.2 for amikacin and 12.3 for kanamycin. The extent of hearing loss was limited and correlated with the cumulative drug dose per kg of body weight during daily administration. At follow-up, 35 (67.3%) of all patients had successful outcome; there were no relapses. At a median dose of 6.5 mg/kg, a correlation was found between the dose per kg of body weight during daily dosing and the extent of hearing loss in dB at 8,000 Hz. These findings suggest that the efficacy at this lower dosage is maintained with limited toxicity. A randomized controlled trial should provide final proof of the safety and efficacy of TDM-guided use of aminoglycosides in MDR-TB treatment.

Characterization of extensively drug-resistant Mycobacterium tuberculosis isolates circulating in Siberia.

BACKGROUND: The spread of multidrug-resistant (MDR) and extensively drug-resistant (XDR) Mycobacterium tuberculosis compromises effective control of tuberculosis (TB) in Siberia. Early identification of drug-resistant isolates is, therefore, crucial for effective treatment of this disease. The aim of this study was to conduct drug susceptibility testing and identify mutations in drug resistance genes in clinical isolates of M. tuberculosis from some TB patients presenting for treatment in Siberia. METHODS: Thirty randomly selected clinical isolates of M. tuberculosis were obtained from the Novosibirsk Research Institute of Tuberculosis, Russia. Isolates were screened for drug resistance and characterized by variable number of tandem repeats (VNTR)-typing using 15 standard and four additional loci. Deligotyping on multiple large sequences was performed using 10 loci. RESULTS: Twenty-nine of the isolates were assigned XDR status. Twenty-eight isolates belonged to the M. tuberculosis Beijing family, from which 11 isolates were considered the M11 type (39%), two the M2 type (7%), and one the M33 type (3%). Seventeen isolates (60.7%) from this family exhibited unique genetic patterns. The remaining two isolates belonged to the Latino-American Mediterranean family. Gene sequences (rpoB, katG, rrs, rpsL, tlyA, gidB, gyrA, gyrB) were analyzed to identify mutations that confer resistance to rifampicin, isoniazid, amikacin, kanamycin, capreomycin, and ofloxacin. The most common mutations among the XDR isolates were S531L in RpoB, S315T in KatG, various codon 94 mutations in gyrA, A90V in GyrA, K43R in RpsL, and 1401 A → G in rrs; these confer resistance to rifampicin, isoniazid, ofloxacin, streptomycin and kanamycin/capreomycin, respectively. There was high congruence between the two typing methods (VNTR typing and deligotyping) and RD105, RD149, RD152, RD181, and RD207 regions of difference were absent from the 28 Beijing family isolates. CONCLUSIONS: Deligotyping can be used for rapid and reliable screening of M. tuberculosis isolates, followed by more in-depth genotyping. Identification of Beijing family isolates with extensive drug resistance confirms that such strains have epidemiological importance in Siberia. Rapid detection of mutations that lead to drug resistance should facilitate selection of effective drug therapies, and the development of early prevention strategies to combat this infection.

[The changes and the significance of cellular immune function in peripheral blood of patients with multidrug-resistant and extensively drug-resistant pulmonary tuberculosis].

OBJECTIVE: To explore the expressions and the significance of CD(3)(+)CD(16)(+)CD(56)(+) NKT cells, CD(3)(-)CD(16)(+)CD(56)(+) NK cells and T lymphocyte subsets in peripheral blood of patients with multi-drug resistant (MDR-TB) and extensively drug-resistant (XDR-TB) pulmonary tuberculosis. METHODS: The data of 316 patients with pulmonary tuberculosis hospitalized in Shanghai Pulmonary Hospital from January 2008 to June 2009 were retrospectively analyzed, of whom 119 were newly diagnosed, and 197 were retreated patients. There were 204 males and 112 females, aged from 17 - 88 years, mean (44 ± 16) years. According to the results of drug-resistance, these patients were divided into a MDR group, an XDR group and a sensitive group. There were 146 patients in the MDR group, with 102 males and 44 females, aged from 19 - 84 years, mean (42 ± 16) years. There were 77 patients in the XDR group, with 42 males and 35 females, aged from 18 - 88 years, mean (50 ± 16) years. There were 93 patients in the susceptible group, with 60 males and 33 females, aged from 17 - 83 years, mean (43 ± 19) years. According to the distribution of cavitation in lung fields, these patients were also divided into 1 - 2 lung field affected group (n = 132), 3 - 4 lung field affected group (n = 49) and 5 - 6 lung field affected group (n = 9). The frequencies of NKT cells, NK cells and T cells from whole blood were tested by flow cytometry. Rank test (SAS software) was used for statistic analyses. RESULTS: The expression rate of NKT cells and NK cells was the highest in the XDR group [11% (6% - 16%) and 7% (4% - 12%)], as compared to the MDR group [8% (5% - 14%) and 6% (4% - 11%)], and the susceptible group [7% (4% - 11%) and 5% (3% - 9%)], the difference being statistically significant (H = 6.478 - 8.369, P < 0.05). The expression rate of the NKT (14 ± 9)% and NK cells (11 ± 7)% in males of the XDR group was significantly higher than that in females [NKT (9 ± 5)% and NK cell (6 ± 4)%], while CD(4) (38 ± 10)% and CD(4)/CD(8) (1.9 ± 1.3) were significantly lower than those of the females [CD(4) (44 ± 10)% and CD(4)/CD(8)(2.2 ± 0.7)], the difference being statistically significant (z = -2.91 - -2.79, P < 0.05, P < 0.01). The expression rate of CD(4) (42 ± 9)% was the highest, but CD(8) (22 ± 8)% was the lowest in the 1 - 2 lung field group. While in the 5 - 6 lung field group, the expression rate of CD(4) (36 ± 11)% was the lowest, CD(8) (28 ± 12)% was the highest, and CD(4)/CD(8) (1.5 ± 0.8) was the lowest, the difference being statistically significant (H = 8.404 - 16.175, P < 0.01). CONCLUSIONS: With the increasing level of drug resistance, the expression rate of NKT cells and NK cells increased, while the expression of T cell subsets did not change. The value of CD(4) and CD(4)/CD(8) in peripheral blood decreased, but CD(8) increased as the extent of cavitation increased in these patients. The impairment of cellular immune function in XDR-TB was more prominent in male patients.

Blood cultures for the diagnosis of multidrug-resistant and extensively drug-resistant tuberculosis among HIV-infected patients from rural South Africa: a cross-sectional study.

BACKGROUND: The yield of mycobacterial blood cultures for multidrug-resistant (MDR) and extensively drug-resistant tuberculosis (XDR-TB) among drug-resistant TB suspects has not been described. METHODS: We performed a retrospective, cross-sectional analysis to determine the yield of mycobacterial blood cultures for MDR-TB and XDR-TB among patients suspected of drug-resistant TB from rural South Africa. Secondary outcomes included risk factors of Mycobacterium tuberculosis bacteremia and the additive yield of mycobacterial blood cultures compared to sputum culture. RESULTS: From 9/1/2006 to 12/31/2008, 130 patients suspected of drug-resistant TB were evaluated with mycobacterial blood culture. Each patient had a single mycobacterial blood culture with 41 (32%) positive for M. tuberculosis, of which 20 (49%) were XDR-TB and 8 (20%) were MDR-TB. One hundred fourteen (88%) patients were known to be HIV-infected. Patients on antiretroviral therapy were significantly less likely to have a positive blood culture for M. tuberculosis (p = 0.002). The diagnosis of MDR or XDR-TB was made by blood culture alone in 12 patients. CONCLUSIONS: Mycobacterial blood cultures provided an additive yield for diagnosis of drug-resistant TB in patients with HIV from rural South Africa. The use of mycobacterial blood cultures should be considered in all patients suspected of drug-resistant TB in similar settings.

Study on the relationship between changes of immune cells and TNF-α in peripheral blood of patients with multidrug-resistant and extensively drug-resistant tuberculosis.

OBJECTIVE: To investigate the relationship between changes in CD4- and CD8-positive immune cells and TNF-α in the peripheral blood of patients affected by multidrug-resistant and extensively drug-resistant tuberculosis. PATIENTS AND METHODS: 179 patients suffering from tuberculosis treated in the Chest Hospital of Hebei from April 2010 to December 2015 were selected for the study. There were 47 cases affected by drug-resistant tuberculosis and 132 cases affected by non-drug-resistant tuberculosis. The control group included 183 healthy subjects examined during the same period. ELISA was used to compare and analyze serum levels of TNF-α, CD4- and CD8-positive cell levels, and CD4/CD8 ratio in the two groups. RESULTS: CD4- and CD8-positive cell count, CD4/CD8 ratio, and serum TNF-a were significantly higher in patients with drug-resistant tuberculosis compared with healthy controls and the non-drug-resistant tuberculosis patients (p < 0.05). There was a positive correlation between TNF-α level and CD4/CD8 ratio (r=0.892, p < 0.05). Before treatment, the differences in the levels of TNF-a in the different groups of drug-resistant patients were insignificant (p >0.05). After treatment, the levels of TNF-a in the different groups of drug-resistant patients were decreased, except for patients with extensively drug-resistant tuberculosis, whose levels were significantly decreased compared with before treatment (t = 0.648, p>0.05). The differences in the levels of TNF-α in the other groups of patients before and after treatment were statistically significant (t = 8.497, 6.258, 5.346, p < 0.05, fully sensitive tuberculosis single drug-resistant tuberculosis, multidrug-resistant tuberculosis, respectively). CONCLUSIONS: The level of TNF-α plays a critical role in the evaluation of the severity of patients with drug-resistant tuberculosis and it has a clinical value.

Rapid evaluation in whole blood culture of regimens for XDR-TB containing PNU-100480 (sutezolid), TMC207, PA-824, SQ109, and pyrazinamide.

There presently is no rapid method to assess the bactericidal activity of new regimens for tuberculosis. This study examined PNU-100480, TMC207, PA-824, SQ109, and pyrazinamide, singly and in various combinations, against intracellular M. tuberculosis, using whole blood culture (WBA). The addition of 1,25-dihydroxy vitamin D facilitated detection of the activity of TMC207 in the 3-day cultures. Pyrazinamide failed to show significant activity against a PZA-resistant strain (M. bovis BCG), and was not further considered. Low, mid, and high therapeutic concentrations of each remaining drug were tested individually and in a paired checkerboard fashion. Observed bactericidal activity was compared to that predicted by the sum of the effects of individual drugs. Combinations of PNU-100480, TMC207, and SQ109 were fully additive, whereas those including PA-824 were less than additive or antagonistic. The cumulative activities of 2, 3, and 4 drug combinations were predicted based on the observed concentration-activity relationship, published pharmacokinetic data, and, for PNU-100480, published WBA data after oral dosing. The most active regimens, including PNU-100480, TMC207, and SQ109, were predicted to have cumulative activity comparable to standard TB therapy. Further testing of regimens including these compounds is warranted. Measurement of whole blood bactericidal activity can accelerate the development of novel TB regimens.