Emerging Antimicrobial Resistance.

The burden of emerging antimicrobial resistance (AMR) in the United States is significant and even greater worldwide. Mitigation efforts have decreased the incidence and deaths from antimicrobial-resistant organisms in the United States. Yet more than 2.8 million antimicrobial-resistant infections occur every year and more than 35,000 patients die as a result. Infection prevention and control, data tracking, antimicrobial stewardship, vaccines, therapeutics, diagnostics, and sanitation are all required to decrease AMR threats. In 2019, in the second version of the Centers for Disease Control and Prevention (CDC) report on antibiotic-resistant threats, the agency categorized AMR threats as urgent, serious, concerning, or to be watched. This review will discuss the following aspects of each bacterium in the CDC report: estimated numbers of cases and deaths, identify the better known and impactful mechanisms of resistance, diagnostic testing and its limitations, and current and possible future therapies. This review also presents anatomical pathology case examples that highlight the altered morphology of antibiotic partially treated bacteria in tissues.

Variants associated with Bedaquiline (BDQ) resistance identified in Rv0678 and efflux pump genes in Mycobacterium tuberculosis isolates from BDQ naïve TB patients in Pakistan.

BACKGROUND: Mutations in the Rv0678, pepQ and atpE genes of Mycobacterium tuberculosis (MTB) have been reported to be associated with reduced antimycobacterial susceptibility to bedaquiline (BDQ). Resistance conferring mutations in treatment naïve MTB strains is likely to have implications for BDQ based new drug regimen that aim to shorten treatment duration. We therefore investigated the genetic basis of resistance to BDQ in MTB clinical isolates from BDQ naïve TB patients from Pakistan. In addition, mutations in genes associated with efflux pumps were investigated as an alternate mechanism of resistance. METHODS: Based on convenience sampling, we studied 48 MTB clinical isolates from BDQ naïve TB patients. These isolates (from our strain bank) included 38 MDR/pre-XDR/XDR (10 BDQ resistant, 8 BDQ intermediate and 20 BDQ susceptible) and 10 pan drug susceptible MTB isolates. All strains were subjected to whole genome sequencing and genomes were analysed to identify variants in Rv0678, pepQ, atpE, Rv1979c, mmpLS and mmpL5 and drug resistance associated efflux pump genes. RESULTS: Of the BDQ resistant and intermediate strains 44% (8/18) had variants in Rv0678 including; two reported mutations S63R/G, six previously unreported variants; L40F, R50Q and R107C and three frameshift mutations; G25fs, D64fs and D109fs. Variants in efflux pumps; Rv1273c (G462K), Rv0507c (R426H) and Rv1634c (E198R) were found to be present in drug resistant isolates including BDQ resistant and intermediate isolates. E198R in efflux pump gene Rv1634c was the most frequently occurring variant in BDQ resistant and intermediate isolates (n = 10). CONCLUSION: We found RAVs in Rv0678 to be commonly associated with BDQ resistance. Further confirmation of the role of variants in efflux pump genes in resistance is required so that they may be incorporated in genome-based diagnostics for drug resistant MTB.

Part I Antimicrobial resistance: Bacterial pathogens of dermatologic significance and implications of rising resistance.

Although the COVID-19 pandemic has been the defining global health crisis of our time, public health officials have been sounding the alarm of another ominous threat for years: an impending antimicrobial resistance crisis. In dermatology, antibiotics are often used for prolonged courses in the treatment of skin and soft tissue infections and common inflammatory skin conditions, increasing the risk of microbiome alteration and antibiotic-related adverse effects, all while exerting consequential selective pressures on both pathogenic and bystander bacteria. In this review, we hope to raise awareness of the crisis of antimicrobial resistance and review resistance concerns related to dermatology-relevant bacterial pathogens.

[Influence of surgical sanation of patients with destructive tuberculosis on the prevalence of tuberculosis and mortality]. / Vliianie khirurgicheskoi sanatsii kontingentov bol'nykh destruktivnym tuberkulezom na osnovnye pokazateli rasprostranennosti i smertnosti ot tuberkuleza.

OBJECTIVE: To analyze the influence of surgical sanation of patients with destructive tuberculosis on the prevalence of tuberculosis and mortality. MATERIAL AND METHODS: The strategy of treatment for new cases of destructive pulmonary tuberculosis was developed in the Perelman Department of Phthisiopulmonology and Thoracic Surgery of the Sechenov First Moscow State Medical University. This strategy was applied in the tuberculosis surgical department of the Tambov Regional Dispensary in 2013-2017. A register of patients with pulmonary destruction and bacterial excretion was developed and personal treatment plans were applied. Patients were divided into 3 groups depending on the treatment mode. The main group A consisted of patients who underwent surgical treatment. Surgery was not performed due to failure or discontinuation of treatment in the comparison group B. Group C included patients without indications or with contraindications for surgical treatment. RESULTS: Treatment efficacy considering destruction cavities closure and abacillation was 97.2% in group A, 41.4% in group B and 39.8% in group C. Surgical approach for patients with destructive tuberculosis reduced the number of patients in the register by 3.3 times (from 516 to 158) within 4 years. A significant reduction of the bacillary core allows breaking the infection chain, that affects the main epidemiological indicators. Reduced incidence of tuberculosis is observed in short-term period, but even greater impact of this factor should be expected in long-term follow-up. CONCLUSION: Surgical approach in complex treatment of destructive pulmonary tuberculosis is valuable to improve efficacy of management of these patients and reduce mortality rate.

[Impact of surgical sanation of patients with destructive tuberculosis on the prevalence of tuberculosis and mortality of these patients]. / Vliyanie khirurgicheskoi sanatsii kontingentov bol'nykh destruktivnym tuberkulezom na osnovnye pokazateli rasprostranennosti i smertnosti ot tuberkuleza.

OBJECTIVE: To analyze the impact of surgical sanation of patients with destructive tuberculosis on the prevalence of tuberculosis and mortality of these patients. MATERIAL AND METHODS: Treatment strategy for destructive pulmonary tuberculosis de novo was developed in the Sechenov First Moscow State Medical University. This strategy was applied at the Surgical Department of the Regional Tambov Tuberculosis Dispensary in 2013-2017. We formed a register of patients with pulmonary destruction and bacterial excretion and developed a personal treatment plan. All patients were divided into 3 groups (group A - surgical treatment, group B - no surgery due to refusal or discontinuation of treatment, group C - patients with contraindications or no indications for surgical treatment). RESULTS: Treatment efficacy considering closure of destruction cavities and abacillation was maximal in group A - 97.2%, 41.4% in group B and 39.8% in group C. The number of patients with pulmonary destruction and bacterial excretion has decreased by 3.3 times (from 516 to 158) or 69.8% for 4 years of extensive application of surgical treatment protocol. A significant reduction of 'bacillary core' interrupted infection chain and affected the main epidemiological characteristics. Short-term reduction of the incidence of tuberculosis may be expected. However, even more significant impact of this factor should be expected in the long-term period. CONCLUSION: Surgical treatment of destructive pulmonary tuberculosis improves efficacy of the management of these patients and reduces mortality rate.

Automated real-time detection of drug-resistant Mycobacterium tuberculosis on a lab-on-a-disc by Recombinase Polymerase Amplification.

With the emergence of multi- and extensive-drug (MDR/XDR) resistant Mycobacterium tuberculosis (M. tb), tuberculosis (TB) persists as one of the world's leading causes of death. Recently, isothermal DNA amplification methods received much attention due to their ease of translation onto portable point-of-care (POC) devices for TB diagnosis. In this study, we aimed to devise a simple yet robust detection method for M. tb. Amongst the numerous up-and-coming isothermal techniques, Recombinase Polymerase Amplification (RPA) was chosen for a real-time detection of TB with or without MDR. In our platform, real-time RPA (RT-RPA) was integrated on a lab-on-a-disc (LOAD) with on-board power to maintain temperature for DNA amplification. Sputa collected from healthy volunteers were spiked with respective target M. tb samples for testing. A limit of detection of 102 colony-forming unit per millilitre in 15 min was achieved, making early detection and differentiation of M. tb strains highly feasible in extreme POC settings. Our RT-RPA LOAD platform has also been successfully applied in the differentiation of MDR-TB from H37Ra, an attenuated TB strain. In summary, a quantitative RT-RPA on LOAD assay with a high level of sensitivity was developed as a foundation for further developments in medical bedside and POC diagnostics.

Antibacterial and anticancer activity of a series of novel peptides incorporating cyclic tetra-substituted C(α) amino acids.

Eleven antimicrobial peptides (AMP) based on the incorporation of cyclic tetra substituted C(α) amino acids, as well as other unnatural amino acids were designed, synthesized and screened for in vitro activity against 18 strains of bacteria as well as 12 cancer cell lines. The AMPs discussed herein are derived from the following peptide sequence: Ac-GF(X)G(X)B(X)G(X)F(X)G(X)GB(X)BBBB-amide, X=any one of the following residues, A5c, A6c, Tic or Oic and B=any one of the following residues, Arg, Lys, Orn, Dpr or Dab. A diversity of in vitro inhibitory activity was observed for these AMPs. Several analogs exhibited single digit µM activity against drug resistant bacteria including; multiple drug resistant Mycobacterium tuberculosis, extremely drug resistant Mycobacterium tuberculosis and MRSA. The physicochemical properties of the basic amino acid residues incorporated into these AMPs seem to play a major role in defining antibacterial activity. Overall hydrophobicity seems to play a limited role in defining antibacterial activity. The ESKAPE pathogens were used to compare the activity of these AMPs to another family of synthetic AMPs incorporating the unnatural amino acids Tic and Oic. In most cases similarly substituted members of both families exhibited similar inhibitory activity against the ESKAPE pathogens. In specific cases differences in activity as high as 15 fold were observed between analogs. In addition four of these AMPs exhibited promising IC50 (<7.5µM) values against 12 different and diverse cancer cell lines. Five other AMPs exhibited promising IC50 (<7.5µM) values against selected cancer cell lines.

Highly Sensitive Detection of Complicated Mutations of Drug Resistance in Mycobacterium tuberculosis Using a Simple, Accurate, Rapid, and Low-Cost Tailored-Design Competitive Wild-Type Blocking Assay.

Establishing simple, rapid, and highly sensitive molecular assays is crucial for timely diagnosis and effective treatment of drug-resistant tuberculosis. However, current genotypic drug susceptibility testing (DST) still encounters enormous challenges including lower sensitivity than phenotypic DST and insufficient accuracy. Herein, a simple, low-cost, multiplex real-time polymerase chain reaction-based assay is established to achieve highly sensitive detection of low-abundant mutants through competitive wild-type blocking (COWTB). Analytical performance of the COWTB assay can achieve 1% or even 0.1% mutants under background of 10 000 wild-type genomes/test. Furthermore, clinical practice feasibility is evaluated to identify resistance to rifampicin (RIF), isoniazid (INH), and streptomycin (SM) on 92 actual clinical samples, its sensitivity is 93.8% for RIF and 100% for INH and SM, and specificity is 100% each for RIF, INH, and SM when using DNA sequencing as the reference standard. In comparison, the sensitivity of reverse dot blotting assay commonly used in clinics is 93.8%, 90.0%, and 84.6%, and the specificity is 96.1%, 98.6%, and 100% for RIF, INH, and SM, respectively. Importantly, the COWTB assay can also be applicable for other drug-resistant mutations and pave a promising detection strategy to fill the gap between phenotypic and genotypic DST for detecting low-abundant drug-resistant M. tuberculosis.

One-pot synthesis of α-Linolenic acid nanoemulsion-templated drug-loaded silica mesocomposites as efficient bactericide against drug-resistant Mycobacterium tuberculosis.

Nowadays, pathogenic infection has posed a severe threat to the public health and environmental sanitation, urging a continuous search of efficacious and safe bactericidal agents of various formulated forms. Here, a facile one-pot hydrothermal preparation of mesoporous silica nanoparticles using ultrasonication-assisted nanoemulsion of α-Linolenic acid (α-LA) as template was developed. The formed silica mesocomposite at water/fatty-acid surface provides an easy yet green synthesis route, which can be generalized for the further encapsulation of hydrophobic drugs such as antimycobacterial Rifampicin (RIF). The obtained α-LA nanoemulsion-templated silica nanoparticles (LNS NPs), with a weight content of ∼17% α-LA in the composite, showed apparent antibacterial effect against Staphylococcus aureus (S. aureus). By comparison, the removal of α-LA from the silica nanoparticles (LNS-1 NPs) resulted in the composite of enlarged pore size with negligible bactericidal activities. Notably, the Isoniazide (INH) and Rifampicin (RIF)-encapsulated LNS NPs exhibited outstanding antimycobacterial activity against both drug-sensitive and drug-resistant Mycobacterium tuberculosis (M. tuberculosis). The obtained highly biocompatible, biosafe and low-energy consumptive α-LA-contained mesostructured silica-based bactericide holds promising therapeutic potentials to tackle the emerging drug-resistant infectious microbes.

Antibiotic Resistance to Mycobacterium tuberculosis and Potential Use of Natural and Biological Products as Alternative Anti-Mycobacterial Agents.

BACKGROUND: Tuberculosis (TB) is an infectious disease caused by the bacillus Mycobacterium tuberculosis (Mtb). TB treatment is based on the administration of three major antibiotics: isoniazid, rifampicin, and pyrazinamide. However, multi-drug resistant (MDR) Mtb strains are increasing around the world, thus, allowing TB to spread around the world. The stringent response is demonstrated by Mtb strains in order to survive under hostile circumstances, even including exposure to antibiotics. The stringent response is mediated by alarmones, which regulate bacterial replication, transcription and translation. Moreover, the Mtb cell wall contributes to the mechanism of antibiotic resistance along with efflux pump activation and biofilm formation. Immunity over the course of TB is managed by M1-macrophages and M2-macrophages, which regulate the immune response against Mtb infection, with the former exerting inflammatory reactions and the latter promoting an anti-inflammatory profile. T helper 1 cells via secretion of interferon (IFN)-gamma, play a protective role in the course of TB, while T regulatory cells secreting interleukin 10, are anti-inflammatory. Alternative therapeutic options against TB require further discussion. In view of the increasing number of MDR Mtb strains, attempts to replace antibiotics with natural and biological products have been object of intensive investigation. Therefore, in this review the anti-Mtb effects exerted by probiotics, polyphenols, antimicrobial peptides and IFN-gamma will be discussed. All the above cited compounds are endowed either with direct antibacterial activity or with anti-inflammatory and immunomodulating characteristics.

Redefining MDR-TB: Comparison of Mycobacterium tuberculosis clinical isolates from Russia and Taiwan.

Multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis are global challenges due to the limited number of effective drugs for treatment. Treatment with less than 4-5 effective drugs might lead to the further emergence of drug resistance and poor clinical outcomes. For better prediction of treatment outcomes, we compared drug-resistance profiles of consecutive clinical MDR Mycobacterium tuberculosis isolates from high- and low-burden settings. This was a retrospective cohort study. We analysed 225 and 229 MDR isolates from Moscow (Russia) and Taiwan, respectively, obtained between 2014 and 2015. Drug susceptibility testing was performed by the Bactec MGIT 960 automated system and the agar proportion method. Detection of resistance-associated mutations in the M. tuberculosis genome was carried out by an array and/or sequencing of selected loci. The principal differences between resistance profiles of MDR isolates in the two countries were the percentages of pre-XDR (40.9% vs. 14.8%) and XDR (34.7% vs. 1.7%) isolates, both of which were significantly higher in Moscow isolates. Forty-eight (33%) of 147 MDR and pre-XDR Russian isolates fall into a group with less than four effective drugs, which accounts for 40% (N = 120) of these isolates. The other 60% in this group were XDR strains (N = 72). Consequently, the average number of effective anti-tuberculosis drugs for MDR-TB treatment was lower for Russian isolates (3 vs. 7). Furthermore, a notable percentage (9%) of isolates resistant to kanamycin harboured mutations in the whiB7 locus, which was not detected by molecular tests targeting common mutations in the rrs and eis loci. We found that 98.2% and 45.9% of MDR isolates from Moscow and Taiwan, respectively, were resistant to streptomycin. Molecular tests for detecting resistance to drugs other than rifampicin, isoniazid, fluoroquinolones, and second-line injectable drugs are needed for individualized therapy. The conventional MDR treatment schemes most probably fail in these cases due to the limited number of effective drugs.

Synthesis and biological evaluation of moxifloxacin-acetyl-1,2,3-1H-triazole-methylene-isatin hybrids as potential anti-tubercular agents against both drug-susceptible and drug-resistant Mycobacterium tuberculosis strains.

Herein, synthesis and biological evaluation of fourteen moxifloxacin-acetyl-1,2,3-1H-triazole-methylene-isatin hybrids as potential anti-tubercular agents against both drug-susceptible (MTB H37Rv), rifampicin-resistant and multidrug-resistant Mycobacterium tuberculosis strains were reported, and cytotoxicity towards VERO cells as well as inhibitory activity against MTB DNA gyrase were also discussed in this paper. The structure-activity relationship and structure-cytotoxicity relationship demonstrated that substituents on the C-3 and C-5/C-7 positions of isatin framework were closely related with the anti-mycobacterial activity and cytotoxicity. The most active hybrids 8h and 8l (MIC: 0.12-0.5 µg/mL) showed excellent activity which was no inferior to the parent moxifloxacin against the tested drug-susceptible, rifampicin-resistant and multidrug-resistant Mycobacterium tuberculosis strains, demonstrating their potential application as novel anti-tubercular candidates.

Benzofuran-isatin hybrids and their in vitro anti-mycobacterial activities against multi-drug resistant Mycobacterium tuberculosis.

A series of benzofuran-isatin hybrids 6a-n and 7a-g linked by alkyl linkers were designed and synthesized. Among them, hybrids 6a-l and 7a-g were assessed for their in vitro anti-mycobacterial activities against two multi-drug resistant Mycobacterium tuberculosis (MDR-MTB) strains and the cytotoxicity towards CHO cells. The preliminary results indicated that all hybrids (MIC: 0.125-16 µg/mL) showed excellent activity against the tested MDR-MTB strains, and low cytotoxicity (CC50: 64->512 µg/mL) towards CHO cells. Among them, hybrid 7e (MIC: 0.125 and 0.25 µg/mL) was highly active against the tested two MDR-MTB strains, which was 8-16 folds better than ciprofloxacin (MIC: 1 and 4 µg/mL), ≥512 folds more potent than rifampicin (MIC: 64 and > 128 µg/mL) and isoniazid (MIC: >128 µg/mL), but it was less active than TAM16 (MIC: <0.06 µg/mL). Moreover, the hybrid 7e (CC50: 128 µg/mL) also showed low cytotoxicity towards CHO cells, and high selectivity index (1,024). However, the metabolic stability and in vivo pharmacokinetic profiles of hybrid 7e were inferior to TAM16, so it still needs to be modified so as to get the optimized hybrid for potential use in mycobacterial treatment.

Clinical Management of Drug-resistant Mycobacterium tuberculosis Strains: Pathogen-targeted Versus Host-directed Treatment Approaches.

BACKGROUND: Despite exerted efforts to control and treat Mycobacterium tuberculosis (MTB) strains, Tuberculosis (TB) remains a public health menace. The emergence of complex drug-resistant profiles, such as multi-drug resistant and extensively drug-resistant MTB strains, emphasizes the need for early diagnosis of resistant cases, shorter treatment options, and effective medical interventions. OBJECTIVE: Solutions for better clinical management of drug-resistant cases are either pathogencentered (novel chemotherapy agents) or host-directed approaches (modulating host immune response to prevent MTB invasion and pathogenesis). RESULTS: Despite the overall potentiality of several chemotherapy agents, it is feared that their effectiveness could be challenged by sequential pathogen adaptation tactics. On the contrary, host-directed therapy options might offer a long-term conceivable solution. CONCLUSION: This review discusses the main suggestions proposed so far to resolve the clinical challenges associated with drug resistance, in the context of TB. These suggestions include novel drug delivery approaches that could optimize treatment outcome and increase patients' compliance to the treatment.

Bedaquiline susceptibility test for totally drug-resistant tuberculosis Mycobacterium tuberculosis.

This study aimed to provide information that bedaquilline is significantly effective for treatment of totally drug resistant (TDR) Mycobacterium tuberculosis that shows resistant to all first- and second-line drugs-using an innovative disc agarose channel (DAC) system. Time-lapse images of single bacterial cells under culture conditions with different concentrations of bedaquiline were analysed by image processing software to determine minimum inhibitory concentrations (MICs). Bedaquiline inhibited the growth of TDR M. tuberculosis strains, with MIC values ranging from 0.125 to 0.5 mg/L. The results of the present study demonstrate that bedaquiline, newly approved by the United States Food and Drug Administration (FDA), may offer therapeutic solutions for TDR-TB.

Disinfectant-susceptibility of multi-drug-resistant Mycobacterium tuberculosis isolated in Japan.

BACKGROUND: Multi-drug-resistant Mycobacterium tuberculosis has been an important problem in public health around the world. However, limited information about disinfectant-susceptibility of multi-drug-resistant strain of M. tuberculosis was available. FINDINGS: We studied susceptibility of several Japanese isolates of multi-drug-resistant M. tuberculosis against disinfectants, which are commonly used in clinical and research laboratories. We selected a laboratory reference strain (H37Rv) and eight Japanese isolates, containing five drug-susceptible strains and three multi-drug-resistant strains, and determined profiles of susceptibility against eight disinfectants. The M. tuberculosis strains were distinguished into two groups by the susceptibility profile. There was no relationship between multi-drug-resistance and disinfectant-susceptibility in the M. tuberculosis strains. Cresol soap and oxydol were effective against all strains we tested, regardless of drug resistance. CONCLUSIONS: Disinfectant-resistance is independent from multi-drug-resistance in M. tuberculosis. Cresol soap and oxydol were effective against all strains we tested, regardless of drug resistance.