Acinetobacter baumannii is a major pathogen in hospital-acquired infections notorious for its strong acquired resistance and complex drug resistance mechanisms. Owing to the lack of effective drugs, the mortality rate of extensively drug-resistant A. baumannii pneumonia can reach as high as 65%. This article analyzes a case where a combination of cefoperazone-sulbactam, polymyxin B, and minocycline with rifampicin successfully treated XDR-AB pulmonary infection. Combination therapy is effective and has a particular clinical value.

This study assessed the presence of the genotoxic impurity 1-methyl-4-nitrosopiperazine (MNP) in 27 batches of rifampicin capsules obtained from 11 manufacturers in China. While they were below the temporary limit of 5 ppm set by the US Food and Drug Administration, the observed levels (0.33-2.36 ppm) exceeded the acceptable threshold of 0.16 ppm. Building upon preliminary findings and degradation experiments, we concluded that MNP is a by-product of the oxidative degradation of rifampicin or is introduced via oxidation or nitrosation during the synthesis process involving 1-methyl-4-aminopiperazine. The pathways of MNP formation were confirmed in this study. Furthermore, we observed that the addition of antioxidants, sealed storage, and selection of dominant crystal forms can aid in controlling MNP levels.

Persister cells are transiently tolerant to antibiotics and are associated with recalcitrant chronic infections due to recolonization of host cells after antibiotic removal. Brucella spp. are facultative pathogens that establish intracellular infection cycles in host cells which results in chronic persistent infections. Brucella abortus forms multi-drug persister cells which are promoted by the (p)ppGpp synthetase Rsh during rifampicin exposure. Here, we confirmed that Rsh promoted persister cells formation in B. abortus stationary phase treated with rifampicin and enrofloxacin. Deletion of the gene for Rsh decreased persister cells level in the presence of these drugs in different growth phases. However, persister cells formation by deletion strain varied in different growth phases in the presence of other antibiotics. Rsh also was involved in persister cells formation during rifampicin treatment under certain stress conditions, including acidic conditions, exposure to PBS, and heat stress. Moreover, Rsh impacted persister cell levels during rifampicin or enrofloxacin treatment in RAW264.7 macrophages. Certain typeIItoxin-antitoxin modules were upregulated under various stress conditions in B. abortus. We established that Rsh positively regulated the type II toxin-antitoxin mbcTA. Moreover, rifampicin-tolerant persister cells formation was elevated and ATP levels were decreased when mbcTA promoter was overexpressed in Rsh deletion background in stationary phase. Our results establish that (p)ppGpp synthetase Rsh plays a key role in B. abortus persistence and may serve as a potent novel target in combination with rifampicin in the development of new therapeutic approaches and prevention strategies to treat chronic infections of Brucella.

BACKGROUND: Tuberculosis (TB), one of the deadliest infectious diseases globally, is increasingly exacerbated in China by the emergence of resistant Mycobacterium tuberculosis (MTB) strains. Drug-resistant TB, including mono-drug resistant TB, multidrug-resistant TB (MDR-TB), and extensively drug-resistant TB (XDR-TB), presents significant public health challenges.
METHODS: We conducted a systematic literature review from January 2010 to February 2024 using databases such as PubMed, Embase, Web of Science, and Google Scholar. Our focus was on empirical data related to drug resistance patterns in newly diagnosed TB cases. Non-empirical studies were excluded through meticulous filtering. For meta-analysis, we used Review Manager (RevMan) 5.2 and assessed evidence quality using the Newcastle-Ottawa Scale (NOS).
RESULTS: Our search strategy identified 40 studies that met the inclusion criteria, encompassing a total sample size of 87,667 participants. Among new TB cases, the estimated prevalence of MDR-TB in China was 6.9% (95% CI: 5.6-8.1%). Prevalence rates for mono-drug resistance to first-line anti-TB medications were as follows: isoniazid at 18.2% (95% CI: 16.4-20.6%), rifampicin at 10.5% (95% CI: 8.6-12.8%), and ethambutol at 5.7% (95% CI: 4.1-7.3%). The prevalence of streptomycin resistance, a former first-line anti-TB drug, was 17.1% (95% CI: 14.6-19.1%). The prevalence of other types of mono-drug resistance was 15.2% (95% CI: 13.9-17.3%), and for XDR-TB, it was 0.9% (95% CI: 0.6-1.4%).
CONCLUSIONS: The high prevalence of drug-resistant TB in China poses a significant public health challenge. There is an urgent need for targeted interventions and continued surveillance to combat the spread of drug-resistant TB.

OBJECTIVE: Currently, body weight-based dosing of rifampicin is recommended. But lately, fat-free mass (FFM) was reported to be superior to body weight (BW). The present evaluation aimed to assess the influence of body mass-related covariates on rifampicin\'s pharmacokinetics (PK) parameters in more detail using non-linear mixed effects modeling (NLMEM).
METHODS: Twenty-four healthy Caucasian volunteers were enrolled in a bioequivalence study, each receiving a test and a reference tablet of 600 mg of rifampicin separated by a wash-out period of at least 9 days. Monolix version 2023R1 was used for NLMEM. Monte Carlo simulations (MCS) were performed to visualize the relationship of body size descriptors to the exposure to rifampicin.
RESULTS: A one-compartment model with nonlinear (Michaelis-Menten) elimination and zero-order absorption kinetics with a lag time best described the data. The covariate model including fat-free mass (FFM) on volume of distribution (V/F) and on maximum elimination rate (Vmax/F) lowered the objective function value (OFV) by 56.4. The second-best covariate model of sex on V/F and Vmax/F and BW on V/F reduced the OFV by 51.2. The decrease in unexplained inter-individual variability on Vmax/F in both covariate models was similar. For a given dose, MCS showed lower exposure to rifampicin with higher FFM and accordingly in males compared to females with the same BW and body height.
CONCLUSIONS: Our results indicate that beyond BW, body composition as reflected by FFM could also be relevant for optimized dosing of rifampicin. This assumption needs to be studied further in patients treated with rifampicin.

Trends in and risk factors for drug resistance in Mycobacterium tuberculosis (M. tuberculosis) in human immunodeficiency virus (HIV)-infected patients with active tuberculosis were analyzed. The clinical data of M. tuberculosis and HIV-coinfected patients treated at the Shanghai Public Health Clinical Center between 2010 and 2022 were collected. The diagnosis of tuberculosis was confirmed by solid or liquid culture. The phenotypic drug susceptibility test was carried out via the proportional method, and the resistance to first-line and second-line drugs was analyzed. Logistic regression analysis was performed to identify associated risk factors for drug resistance in M. tuberculosis. Of the 304 patients with a M. tuberculosis-positive culture and first-line drug susceptibility test results, 114 (37.5%) were resistant to at least one first-line anti-tuberculosis drug. Of the 93 patients with first-line and second-line drug susceptibility test results, 40 (43%) were resistant to at least one anti-tuberculosis drug, and 20 (21.5%), 27 (29.0%), 19 (20.4%), 16 (17.2%), and 14 (15.1%) were resistant to rifampicin, streptomycin, ofloxacin, levofloxacin, and moxifloxacin, respectively; 17 patients (18.3%) had multidrug-resistant tuberculosis (MDR-TB). Between 2010 and 2021, the rate of resistance to streptomycin and rifampicin ranged from 14.3% to 40.0% and from 8.0% to 26.3%, respectively, showing an increasing trend year by year. From 2016 to 2021, the rate of resistance to quinolones fluctuated between 7.7% and 27.8%, exhibiting an overall upward trend. Logistic regression analysis showed that being aged <60 years old was a risk factor for streptomycin resistance, mono-drug resistance, and any-drug resistance (RR 4.139, p = 0.023; RR 7.734, p = 0.047; RR 3.733, p = 0.009). Retreatment tuberculosis was a risk factor for resistance to rifampicin, ofloxacin, of levofloxacin (RR 2.984, p = 0.047; RR 4.517, p = 0.038; RR 6.277, p = 0.014). The drug resistance rates of M. tuberculosis to rifampicin and to quinolones in HIV/AIDS patients were high and have been increasing year by year. Age and a history of previous anti-tuberculosis treatment were the main factors associated with the development of drug resistance in HIV/AIDS patients with tuberculosis.

Myzus persicae is an important pest that has developed resistance to nearly all currently used insecticidal products. The employment of insecticide synergists is one of the effective strategies that need to be developed for the management of this resistance. Our study showed that treatment with a combination of the antibiotic, rifampicin, with imidacloprid, cyantraniliprole, or clothianidin significantly increased their toxicities against M. persicae, by 2.72, 3.59, and 2.41 folds, respectively. Rifampicin treatment led to a noteworthy reduction in the activities of multifunctional oxidases (by 32.64%) and esterases (by 23.80%), along with a decrease in the expression of the CYP6CY3 gene (by 58.57%) in M. persicae. It also negatively impacted the fitness of the aphids, including weight, life span, number of offspring, and elongation of developmental duration. In addition, bioassays showed that the combination of rifampicin and a detoxification enzyme inhibitor, piperonyl butoxide, or dsRNA of CYP6CY3 further significantly improved the toxicity of imidacloprid against M. persicae, by 6.19- and 7.55-fold, respectively. The present study suggests that development of active ingredients such as rifampicin as candidate synergists, show promise to overcome metabolic resistance to insecticides in aphids.

Rifampicin is the most powerful first-line antibiotic for tuberculosis, which is caused by Mycobacterium tuberculosis. Although accumulating evidence from sequencing data of clinical M. tuberculosis isolates suggested that mutations in the rifampicin-resistance-determining region (RRDR) are strongly associated with rifampicin resistance, the comprehensive characterisation of RRDR polymorphisms that confer this resistance remains challenging. By incorporating I-SceI sites for I-SceI-based integrant removal and utilizing an L5 swap strategy, we efficiently replaced the integrated plasmid with alternative alleles, making mass allelic exchange feasible in mycobacteria. Using this method to establish a fitness-related gain-of function screen, we generated a mutant library that included all single-amino-acid mutations in the RRDR, and identified the important positions corresponding to some well-known rifampicin-resistance mutations (Q513, D516, S522, H525, R529, S531). We also detected a novel two-point mutation located in the RRDR confers a fitness advantage to M. smegmatis in the presence or absence of rifampicin. Our method provides a comprehensive insight into the growth phenotypes of RRDR mutants and should facilitate the development of anti-tuberculosis drugs.

Rifampicin (RIF) is a broad-spectrum antimicrobial agent that is also a first-line drug for treating tuberculosis (TB). Based on the naphthyl ring structure of RIF this study synthesized 16 narrow-spectrum antimicrobial molecules that were specifically anti-Mycobacterium tuberculosis (Mtb). The most potent candidate was 2-((6-hydroxynaphthalen-2-yl) methylene) hydrazine-1-carbothioamide (compound 3c) with minimum inhibitory concentration (MIC) of 1 μg/mL against Mtb. Synergistic anti-Mtb test indicated that none of the combinations of 3c with the major anti-TB drugs are antagonistic. Consistent with RIF, compound 3c induced large amounts of reactive oxygen radicals (ROS) in the cells of Mtb. The killing kinetics of compound 3c and RIF are very similar. Furthermore, molecular docking showed that compound 3c was able to access the RIF binding pocket of the β subunit of Mtb RNA polymerase (RNAP). Experiments in mice showed that compound 3c increased the variety of intestinal flora in mice, while RIF significantly decreased the diversity of intestinal flora in mice. In addition, compound 3c is non-toxic to animal cells with a selection index (SI) much more than 10. The evidence from this study suggests that the further development of 3c could contribute to the development of novel drug for TB treatment.

OBJECTIVE: To develop a semi-mechanistic hepatic compartmental model to predict the effects of rifampicin, a known inducer of CYP3A4 enzyme, on the metabolism of five drugs, in the hope of informing dose adjustments to avoid potential drug-drug interactions.
METHODS: A search was conducted for DDI studies on the interactions between rifampicin and CYP substrates that met specific criteria, including the availability of plasma concentration-time profiles, physical and absorption parameters, pharmacokinetic parameters, and the use of healthy subjects at therapeutic doses. The semi-mechanistic model utilized in this study was improved from its predecessors, incorporating additional parameters such as population data (specifically for Chinese and Caucasians), virtual individuals, gender distribution, age range, dosing time points, and coefficients of variation.
RESULTS: Optimal parameters were identified for our semi-mechanistic model by validating it with clinical data, resulting in a maximum difference of approximately 2-fold between simulated and observed values. PK data of healthy subjects were used for most CYP3A4 substrates, except for gilteritinib, which showed no significant difference between patients and healthy subjects. Dose adjustment of gilteritinib co-administered with rifampicin required a 3-fold increase of the initial dose, while other substrates were further tuned to achieve the desired drug exposure.
CONCLUSIONS: The pharmacokinetic parameters AUCR and CmaxR of drugs metabolized by CYP3A4, when influenced by Rifampicin, were predicted by the semi-mechanistic model to be approximately twice the empirically observed values, which suggests that the semi-mechanistic model was able to reasonably simulate the effect. The doses of four drugs adjusted via simulation to reduce rifampicin interaction.