Rifampin monoresistant tuberculosis and HIV comorbidity in California, 1993-2008: a retrospective cohort study

Rifampin Mono-Resistant Tuberculosis in New York City, 2010-2021: A Retrospective Case Series

Background

Although relatively rare, rifampin mono-resistant tuberculosis (RMR TB) poses important challenges to effective TB treatment and control. Information on the burden of RMR TB and treatment outcomes is needed to inform diagnosis and management.

Methods

Standardized variables were collected from the New York City (NYC) tuberculosis surveillance system for patients treated for RMR TB in NYC during 2010-2021.

Results

Of 7097 TB cases reported in 2010-2021, 31 (<1%) were treated clinically as RMR TB. Five (16%) of these patients had HIV. Seventeen patients (55%) had TB that was rifampin-resistant by both molecular and phenotypic drug susceptibility testing; 2 (6%) had rifampin resistance by phenotypic tests, and molecular tests were not done; and 12 (39%) were identified based only on molecular tests. Among these 12, 7 were rifampin-sensitive by phenotypic tests, and phenotypic testing could not be done for the other 5. Ten of the 31 (32%) were diagnosed in 2010-2015; the other 21 (including 10/12 diagnosed by molecular tests alone) were diagnosed in 2016-2021. Of the 31 patients, 21 (68%) completed treatment (median treatment duration of 18 months). Although the interval between tuberculosis treatment initiation and change to a non-rifamycin-containing regimen decreased significantly during the study period, the overall duration of treatment did not decrease significantly between 2010 and 2021.

Conclusions

Molecular drug susceptibility tests identified cases of RMR TB that were not detected by phenotypic testing and helped enable timely adjustment of tuberculosis treatment regimens. Short-course regimens are needed to reduce duration of treatment for RMR TB.

Patterns of Presentation of Drug-Resistant Tuberculosis in Nigeria: A Retrospective File Review

Background: An understanding of the patterns of drug-resistant tuberculosis (DR-TB) is needed to develop the best diagnostic tools and decide on optimal treatment combination therapies for the management of DR-TB in Nigeria. Objective: We aimed to investigate patterns of DR-TB for the five first-line anti-TB drugs over a period of seven years (2010–2016) and the associated clinical and socio-demographic factors. Methods: A retrospective study recruited 2555 DR-TB patients between 2010 and 2016 across the six geopolitical treatment zones in Nigeria. We determined DR-TB patterns based on standard case definition and their association with demographic and clinical information. Data were analyzed using Statistical Package for Social Sciences (SPSS) software. Independent predictors of DR-TB patterns/types were determined using bivariate and multivariate analyses with a statistical significance of p < 0.05 and a 95% confidence interval. Results: The majority of the participants were males, 66.93% (1710), 31–40 years old, 35.19% (899), previously treated, 77.10% (1909), had received at least two treatments, 411 (49.94%) and were multi-drug resistant, 61.41% (1165). The Southwest zone had the highest number of DR-TB cases, 36.92%. We found an upward trend in the prevalence of DR-TB from 2010 to 2016. Participants who had received one previous treatment showed statistically significant higher rifampicin resistance (59.68%), those with two previous treatments reported a statistically significant higher polydrug resistance (78.57%), and those with three or more previous treatments had a statistically significant higher multidrug resistance (19.83%) (χ2 = 36.39; p = 0.001). Mono-drug resistance and rifampicin resistance were statistically significantly higher in the southwest zone (29.48% and 34.12% respectively), polydrug resistance in the northcentral (20.69%) and south-south zones (20.69%), and multidrug resistance in the southwest (30.03%) and northcentral zones (19.18%) (χ2 = 98.26; p = 0.001). Conclusions: We present patterns of DR-TB across the six geopolitical zones in Nigeria. Clinicians should weigh in on these patterns while deciding on the best first-line drug combinations to optimize treatment outcomes for DR-TB patients. A national scale-up plan for DST services should focus on patients with previous multiple exposures to anti-TB treatments and on those in the Northeastern zone of the country.

Are all antibiotic persisters created equal?

Antibiotic persisters are a sub-population of bacteria able to survive in the presence of bactericidal antibiotic despite the lack of heritable drug resistance mechanisms. This phenomenon exists across many bacterial species and is observed for many different antibiotics. Though these bacteria are often described as “multidrug persisters” very few experiments have been carried out to determine the homogeneity of a persister population to different drugs. Further, there is much debate in the field as to the origins of a persister cell. Is it formed spontaneously? Does it form in response to stress? These questions are particularly pressing in the field of Mycobacterium tuberculosis, where persisters may play a crucial role in the required length of treatment and the development of multidrug resistant organisms. Here we aim to interpret the known mechanisms of antibiotic persistence and how they may relate to improving treatments for M. tuberculosis, exposing the gaps in knowledge that prevent us from answering the question: Are all antibiotic persisters created equal?

Rifampicin Mono-Resistant Tuberculosis-A Review of an Uncommon But Growing Challenge for Global Tuberculosis Control

Tuberculosis (TB) remains the leading cause of death by an infectious pathogen worldwide, and drug-resistant TB is a critical and rising obstacle to global control efforts. Most scientific studies and global TB efforts have focused on multidrug-resistant TB (MDR-TB), meaning isolates resistant to both isoniazid (INH) and rifampicin (RIF). Newer diagnostic tests are resulting in an increasing awareness of RIF-resistant TB in addition to MDR disease. To date, RIF resistance has been assumed to be synonymous with MDR-TB, but this approach may expose TB patients with RIF mono-resistance disease to unnecessarily long and toxic treatment regimens. We review what is currently known about RIF mono-resistant TB, its history and epidemiology, mechanisms of RIF resistance, available diagnostic techniques, treatment outcomes reported globally, and future directions for combatting this disease.

Rifampin-resistant Tuberculosis in the United States, 1998-2014

BACKGROUND

Monoresistance to rifamycins necessitates longer and more toxic regimens for tuberculosis (TB). We examined characteristics and mortality associated with rifampin-monoresistant (RMR) TB in the United States.

METHODS

We analyzed Mycobacterium tuberculosis culture-positive cases reported to the National TB Surveillance System (excluding California) between 1998 and 2014. We defined RMR TB found on initial drug susceptibility testing and possible acquired rifampin-resistant (ARR) TB. We assessed temporal trends in RMR TB. For both classifications of rifampin resistance, we calculated adjusted risk ratios (adjRRs) and 95% confidence intervals (CIs) for characteristics associated with mortality when compared with drug-susceptible TB in multivariable models using backward selection.

RESULTS

Of 180 329 TB cases, 126 431 (70%) were eligible for analysis, with 359 (0.28%) of eligible cases reported as RMR. The percentage of RMR TB cases with HIV declined 4% annually between 1998 and 2014. Persons with HIV and prior TB were more likely to have RMR TB (adjRR, 25.9; 95% CI, 17.6-38.1), as were persons with HIV and no prior TB (adjRR, 3.1; 95% CI, 2.4-4.1) vs those without either characteristic, controlling for other statistically significant variables. RMR cases had greater mortality (adjRR, 1.4; 95% CI, 1.04-1.8), controlling for HIV and other variables. Persons with HIV had greater risk of ARR than persons without HIV (adjRR, 9.6; 95% CI, 6.9-13.3), and ARR was also associated with increased mortality, controlling for HIV and other variables.

CONCLUSIONS

All forms of rifampin resistance were positively associated with HIV infection and increased mortality.

Longitudinal Analysis of Prevalence and Risk Factors of Rifampicin-Resistant Tuberculosis in Zhejiang, China

Objectives

To investigate the factors associated with rifampicin-resistant tuberculosis among drug resistant tuberculosis patients and to determine the correlation of rifampicin-resistant TB with MDR-TB in a high MDR-TB burden province of china.

Methods

A retrospective longitudinal analysis on four surveys of anti-TB drug resistance done in 1998, 2003, 2008, and 2013 in Zhejiang province, China. 4289 sputum-smear microscopy positive suspected tuberculosis patients were eligible at 30 investigation points, chosen by stratified random sampling at survey sites from all over the province. Culturing samples in L-J medium and the drug-susceptibility testing for the 4 first-line anti-TB drugs were performed to all patients. Multivariate logistic regression was carried out to determine the factors associated with the rifampicin-resistance in the study population.

Results

Overall, there were 3832 patients with positive mycobacterial cultures, and 2813 of the isolates (73.4%) were susceptible to all 4 first-line drugs. Analysis of rifampin monoresistant (RMR) TB indicated the prevalence was 1.1% in new cases and 3.4% in previously treated cases. Among the 359 rifampicin resistant TB (RR-TB) cases, 279 (77.7%) were also resistant to isoniazid, indicating MDR-TB. From 1998 to 2013, the proportion of MDR-TB among rifampicin-resistant TB cases varied between 80.0% and 87.5% (P for trend: 0.768) among previously treated cases and varied from 68.6% to 79.5% (P for trend: 0.403) among new cases. Among previously treated patients, those who received treatment for less than 6 months were less likely to have drug resistant TB (OR: 0.40, 95% CI: 0.16–0.97) or MDR-TB (OR: 0.24, 95% CI: 0.07–0.81). Patients who received anti-TB treatment in a general hospital were less likely to develop MDR-TB than those treated in a TB clinic (OR: 0.08, 95% CI: 0.01–0.72).

Conclusion

This study highlights a high proportion of RMR-TB among new RR-TB cases in Zhejiang, China. The management of treatment with rapid and accurate diagnosis of MDR-TB other than only relying on RIF susceptibility testing is crucial for improving adherence and outcomes in patients with drug-resistant TB.

Caracterización clínica y terapéutica de pacientes con tuberculosis pulmonar en Cali

Objetivo: Establecer las características clínicas, sociodemográficas y farmacológicas de pacientes con tuberculosis pulmonar.Metodología: Se realizó un estudio descriptivo, retrospectivo y de corte transversal con una muestra de 157 pacientes. La información se recolectó de la base de datos de la Secretaría de Salud Pública Municipal de la ciudad de Cali durante el año 2013. La asociación entre las variables se estableció mediante la prueba de chi cuadrado empleando el paquete estadístico SPSS Vs 22.0.Resultados: El 62,4% de los pacientes objeto de estudio eran hombres jóvenes y el 72% de estratos socioeconómicos bajos. El 9,2% de los pacientes presentaron tuberculosis pulmonar farmacorresistente (p = 0,0231). La resistencia a la isoniazida fue de 94,2%; a la rifampicina, de 78,8%; a la pirazinamida, de 21,2%; al etambutol, de 25%; y a la estreptomicina, de 48,1%. Los pacientes desnutridos y adictos a las drogas o al alcohol revelaron mayor resistencia a la terapia antituberculosa. Los pacientes con tuberculosis pulmonar farmacorresistente y adictos a sustancias psicoactivas o al alcohol representaron el 19,2%, con diabetes el 15,4% y los coinfectados con el virus de la inmunodeficiencia humana (VIH), el 13,4%.Conclusiones. La alta proporción de hombres con tuberculosis puede estar condicionada a una mayor exposición al agente por ser el grupo más activo laboralmente. Se evidenció una mayor prevalencia de cepas multirresistentes a fármacos de primera línea en pacientes de estratos socioeconómicamente bajos, de grupos marginados y con factores de riesgo como desnutrición y abuso de alcohol y de sustancias psicoactivas.

Drug resistance and Mycobacterium tuberculosis strain diversity in TB/HIV co-infected patients in Ho Chi Minh city, Vietnam

BACKGROUND

Mycobacterium tuberculosis strain diversity and drug resistance among people living with human immunodeficiency virus (HIV) in Vietnam have not been described previously.

METHODS

We examined M. tuberculosis isolates from TB/HIV co-infected patients in Ho Chi Minh City, Vietnam. Drug susceptibility testing (DST), spoligotyping and 24-locus Mycobacterial Interspersed Repetitive Unit (MIRU-24 typing) were performed, and the rpoB, katG, inhA and inhA promoter, rpsL, rrs and embB genes were sequenced in all drug resistant isolates identified.

RESULTS

In total, 84/200 (42.0%) strains demonstrated "any drug resistance"; 17 (8.5%) were multi-drug resistant (MDR). Streptomycin resistance was present in 80 (40.0%) isolates; 95.2% (80/84) with "any drug resistance" and 100% with MDR. No rifampicin monoresistance was detected. Of the rifampicin resistant strains 16/18 (88.9%) had mutations in the 81-bp Rifampicin Resistance Defining Region (RRDR) of the rpoB gene. Isoniazid resistance was mostly associated with Ser315Thr mutations in the katG gene (15/17; 88.2%). Beijing (49.0%) and East African Indian (EAI) lineage strains (35.0%; 56/70 EAI-5) were most common.

CONCLUSION

TB/HIV co-infection in Vietnam was associated with high rates of TB drug resistance, although we were unable to differentiate new from retreatment cases.