Measurement and prediction of antimicrobial resistance in bloodstream infections by ESKAPE pathogens and Escherichia coli

Current trends in antimicrobial resistance of ESKAPEEc pathogens from bloodstream infections - Experience of a tertiary care centre in North India

INTRODUCTION

Bloodstream infections (BSI) due to ESKAPEEc pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumanni, Pseudomonas aeruginosa, Enterobacter spp. and Escherichia coli), cause significant mobility and mortality worldwide and are among the most common healthcare associated infections. Rising rates of antimicrobial resistance (AMR) in India are alarming, because of the high infection rates and poor control of antibiotic use. This single-centre, retrospective study was undertaken to identify the patterns of distribution and antimicrobial resistance of ESKAPEEc pathogens in bloodstream infections.

METHODOLOGY

Blood samples from patients with suspected BSI were cultured and antimicrobial susceptibility testing was performed on automated systems (BD Bactec Fx/BactAlert 3D and Vitek2). The microbiological data on bacterial BSI was retrieved from the laboratory records and antimicrobial resistance profiles were analysed.

RESULTS

10.7% of the blood culture samples showed bacterial growth during the study period (adult > paediatric and intensive care unit (ICU) > ward > outpatient department (OPD)). E. coli (24%) and K. pneumoniae (20.5%) were the predominant species isolated, followed by S. aureus (9.5%) and A. baumanni (9%). High rates of resistance to third generation cephalosporins, β-lactam-β-lactamase inhibitor combinations (BL-BLI) and carbapenems was observed, in Gram-negative isolates, especially from ICU patients. Methicillin-resistant S. aureus (MRSA) isolates increased from 67% to 88% over the five-year period. Vancomycin-resistance among Enterococcus isolates also escalated to 40% in 2022 with 11% linezolid resistance.

CONCLUSION

The study revealed that more than 77% of bloodstream infections were caused by ESKAPEEc pathogens, with high rates of resistance to most antimicrobials. This reinforces the importance of monitoring the frequency of bacteria and antibiograms in individual treatment and hospital infection control programs.

The "COVID effect" in culture-based clinical microbiology: Changes induced by COVID-19 pandemic in a Hungarian tertiary care center

BACKGROUND

The presence of bacterial and fungal coinfections plays an important role in the mortality of patients with coronavirus 2019 (COVID-19). We compared data from the 3 years before and 3 years after the COVID-19 pandemic outbreak to evaluate its effect on the traits of bacterial and fungal diseases.

METHODS

We retrospectively collected and analyzed data on positive respiratory tract samples (n = 13,133 samples from 7717 patients) and blood cultures (n = 23,652 from 9653 patients) between 2017 and 2022 from the Clinical Center of the University of Szeged, Hungary. We also evaluated antimicrobial susceptibility test results derived from 169,020 respiratory samples and 549,729 blood cultures to gain insight into changes in antimicrobial resistance.

RESULTS

The most common respiratory pathogen in the pre-COVID era was Pseudomonas aeruginosa, whereas Candida albicans was the most frequent during the pandemic. The number of respiratory isolates of Acinetobacter baumannii was also markedly increased. In blood cultures, Staphylococcus epidermidis, Escherichia coli, and S. aureus were dominant during the study period, and A. baumannii was widespread in blood cultures during the pandemic years. Resistance to ofloxacin, penicillin, piperacillin-tazobactam, ceftazidime, cefepime, imipenem, ceftolozane-tazobactam, and itraconazole increased significantly in the COVID era.

CONCLUSIONS

During the COVID-19 pandemic, there were changes in the prevalence of respiratory and blood culture pathogens at the Clinical Center of the University of Szeged. C. albicans became the predominant respiratory pathogen, and the number of A. baumannii isolates increased dramatically. Additionally, antimicrobial resistance notably increased during this period.

When it rains it pours: An increased prevalence of intestinal carriage of vancomycin-resistant Enterococcus faecium related to higher use of oral vancomycin in a tertiary care Hungarian clinical centre during the years of the COVID-19 pandemic

OBJECTIVES

This study aims to investigate the association between oral vancomycin consumption and intestinal vancomycin-resistant Enterococcus carriage in the pre- and COVID era in the clinical centre of the University of Szeged, Hungary.

METHODS

This retrospective microbiological examination was carried out using electronically collected data, corresponding to the period between 1 January 2018 and 31 December 2022, at the Department of Medical Microbiology. Data included isolated species and the according antimicrobial susceptibility patterns. Annual consumption data for oral vancomycin consumption were exported from the database of the central pharmacy of the clinical centre. As a strain typing procedure, Fourier transform infrared spectroscopy analysis was used.

RESULTS

There was a significant increase in the number of faecal vancomycin-resistant Enterococcus isolates throughout the study. The prevalence increased significantly during the years of the pandemic. The use of orally administered vancomycin in the clinical centre increased significantly. A strong positive correlation existed between the two phenomena. Several strains with different resistance patterns spread in the clinical centre. Two of these occurred in greater numbers, differing in their high-level aminoglycoside resistance. However, the overall resistance of these strains was stagnating. FTIR analysis revealed that 59 of the 62 strains were also divided into 2 large clusters differing partially in their high-level aminoglycoside resistance.

CONCLUSIONS

During the pandemic, intestinal VRE carriage among clinical centre patients increased significantly, linked to increased oral vancomycin use. Different strains spread, with aminoglycoside resistance being the primary distinction. This highlights the negative impact of the pandemic on VRE carriage.

Dispersion of antimicrobial resistant bacteria in pig farms and in the surrounding environment

BACKGROUND

Antimicrobial resistance has been identified as a major threat to global health. The pig food chain is considered an important source of antimicrobial resistance genes (ARGs). However, there is still a lack of knowledge on the dispersion of ARGs in pig production system, including the external environment.

RESULTS

In the present study, we longitudinally followed one swine farm located in Italy from the weaning phase to the slaughterhouse to comprehensively assess the diversity of ARGs, their diffusion, and the bacteria associated with them. We obtained shotgun metagenomic sequences from 294 samples, including pig feces, farm environment, soil around the farm, wastewater, and slaughterhouse environment. We identified a total of 530 species-level genome bins (SGBs), which allowed us to assess the dispersion of microorganisms and their associated ARGs in the farm system. We identified 309 SGBs being shared between the animals gut microbiome, the internal and external farm environments. Specifically, these SGBs were characterized by a diverse and complex resistome, with ARGs active against 18 different classes of antibiotic compounds, well matching antibiotic use in the pig food chain in Europe.

CONCLUSIONS

Collectively, our results highlight the urgency to implement more effective countermeasures to limit the dispersion of ARGs in the pig food systems and the relevance of metagenomics-based approaches to monitor the spread of ARGs for the safety of the farm working environment and the surrounding ecosystems.

Laboratory automation, informatics, and artificial intelligence: current and future perspectives in clinical microbiology

Clinical diagnostic laboratories produce one product-information-and for this to be valuable, the information must be clinically relevant, accurate, and timely. Although diagnostic information can clearly improve patient outcomes and decrease healthcare costs, technological challenges and laboratory workflow practices affect the timeliness and clinical value of diagnostics. This article will examine how prioritizing laboratory practices in a patient-oriented approach can be used to optimize technology advances for improved patient care.

Artemisia herba-alba sesquiterpenes: in silico inhibition in the ATP-binding pocket

To identify antimicrobial leads for medical applications, metabolites from the aerial part of Artemisia herba-alba were extracted and chromatographically purified. Two new sesquiterpenes, 1β,8α-dihydroxyeudesm-4-en-6β,7α,11βH-12,6-olide (1) and 1β,6α,8α-trihydroxy, 11α-methyl-eudesma-4(15)-en-13-propanoate (2) along with a known eudesmanolide 11-epi-artapshin (3) were identified. Structures were determined by spectroscopic methods including 1D- and 2D-NMR as well as mass spectroscopy. Compound 3 inhibited Gram-positive bacteria Bacillus subtilis, Lactobacillus cereus and Staphylococcus aureus and exhibited antifungal activity against the pathogenic fungus F. solani. The mode-of-action of these antimicrobial sesquiterpenes as bacterial type II DNA topoisomerase and/or DNA gyrase B inhibitors were examined via in silico studies. Such molecular-docking studies were also employed to examine antifungal activity against an N-myristoyl transferase (NMT) target. Compound 3 had the greatest gyrase B binding affinity in the ATP-binding pocket and was found to possess an inhibitory action against non-invasive micro-test technology (NMT).

Prescription of Rifampicin for Staphylococcus aureus Infections Increased the Incidence of Corynebacterium striatum with Decreased Susceptibility to Rifampicin in a Hungarian Clinical Center

Several reports have suggested a role for Corynebacterium striatum as an opportunistic pathogen. The authors have conducted a retrospective study at the Clinical Center of the University of Szeged, Hungary, between 2012 and 2021 that revealed significantly increased rifampicin resistance in this species. This work aimed to investigate the reasons behind this phenomenon. The data were collected corresponding to the period between 1 January 2012 and 31 December 2021 at the Department of Medical Microbiology, University of Szeged. To characterize the resistance trends, the antibiotic resistance index was calculated for each antibiotic in use. Fourteen strains with different resistance patterns were further analyzed with Fourier-transform infrared spectroscopy using the IR Biotyper^®. The decline in C. striatum sensitivity to rifampicin seen during the COVID-19 pandemic may have been attributable to the use of Rifadin^® to treat concomitant Staphylococcus aureus infections. The fact that the IR Biotyper^® typing method revealed that the rifampicin-resistant C. striatum strains were closely related supports this hypothesis. The IR Biotyper^® infrared spectroscopy proved to be a modern and fast method to support effective antimicrobial stewardship programs.

Multi-drug resistant ESKAPE pathogens and the uses of plants as their antimicrobial agents

Infections by ESKAPE (Enterococcus sp., Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.) pathogens cause major concern due to their multi-drug resistance (MDR). The ESKAPE pathogens are frequently linked to greater mortality, diseases, and economic burden in healthcare worldwide. Therefore, the use of plants as a natural source of antimicrobial agents provide a solution as they are easily available and safe to use. These natural drugs can also be enhanced by incorporating silver nanoparticles and combining them with existing antibiotics. By focussing the attention on the ESKAPE organisms, the MDR issue can be addressed much better.

Bacterial infections epidemiology and factors associated with multidrug resistance in the northern region of Ghana

Bacterial infections caused by multidrug resistant organisms are a major global threat. There is still a knowledge gap on this situation in the Northern Region of Ghana. This study determined the prevalence and resistance profile of bacterial infections. It also identified factors associated with multidrug resistance in the study area. This was a retrospective cross-sectional design and it analyzed data from the samples received at the Tamale Zonal Public Health Reference Laboratory from June 2018 to May 2022. The data were analyzed using the R software version 4.2.0. Univariate and multivariable binary logistic regression analyses were used to determine the factors associated with multidrug resistance. The samples included all specimen types possible. The specimens were collected for the purpose of clinical bacteriology diagnostics. Overall a total of 1222 isolates were obtained. The three (3) main bacteria responsible for infections were: Klebsiella spp. (27%), Moraxella spp. (22%), Escherichia spp. (16%). High resistance levels were found against the tested antibiotics and about 41.60% of the bacterial strains isolated were multidrug resistant. Hospitalization was associated with multidrug resistance in univariate (COR 1.96; 95% CI 1.43-2.71; P-value < 0.001) and multivariable analyses (AOR 1.78; 95% CI 1.28-2.49; P-value < 0.001). There is the need for further research on the molecular epidemiology of antibiotic resistance genes in the study area to effectively control the spread of multidrug resistant pathogens. In addition, efforts to build the capacity of health professionals on infection prevention and control as well as diagnostic and antimicrobial stewardship needs urgent attention.

Synthesis of silver nanoparticles using Emilia sonchifolia plant for treatment of bloodstream diseases caused by Escherichia coli

OBJECTIVES

Among infectious diseases, bloodstream infection (BSI) caused by gram-negative bacteria (E. coli) is the leading cause of death worldwide. However, the bacteria have produced resistance to many of these antibiotics. Thus, the present study aimed to develop silver nanoparticles (AgNPs) loaded with Emilia sonchifolia (ES) extract (ES-AgNPs) to treat BSI efficiently.

METHODS

AgNPs were synthesized by reduction of silver nitrate (AgNO₃) solution by ES extract. Furthermore, these ES-AgNPs were characterized for particle size and zeta potential, crystallinity by powder X-ray diffraction (P-XRD) technique, in vitro antibacterial activity, time-kill assay, film bio adhesion, and fluorescence assay.

RESULTS

Surface plasmon resonance (SPR) has been used to confirm the formation of AgNPs by seeing a shift in colour to dark-brown. The ES-AgNPs displayed a mean particle size of 137±3nm (PDI of 0.168±0.02) and zeta potential of 18.2±0.8mV. Furthermore, according to P-XRD results, the developed AgNPs are highly crystalline. The ES-AgNPs showed effective antibacterial action against E. coli with minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) of 0.4±0.02μg/mL and 0.8±0.03μg/mL, respectively. In addition, ES-AgNPs inhibited biofilm formation and bacterial adhesion in a dose-dependent manner with 100% inhibition obtained in 48h at MBC.

CONCLUSIONS

Present research work revealed that the ES-AgNPs obtained by green synthesis holds a prominent antibacterial activity in the treatment of BSIs caused by E. coli and they may be used as a competent substitute for current treatments. However, further, in vivo antibacterial studies are required to establish its efficacy in the treatment of BSIs.

Les misérables: a Parallel Between Antimicrobial Resistance and COVID-19 in Underdeveloped and Developing Countries

Purpose of Review

The COVID-19 pandemic has been responsible for more than 6.3 million deaths worldwide. During the pandemic, the indiscriminate use of antibiotics has increased, contributing to the spread of multidrug-resistant bacteria. In this review, we aim to determine the spread and impact of antibiotic treatments in patients with COVID-19, focusing on underdeveloped and developing countries.

Recent Findings

Meta-analysis revealed that bacterial co-infections and secondary infections are relatively rare in COVID-19 patients, corresponding to less than 20% of hospitalized patients. Even so, most of these patients have received antibiotic treatments.

Summary

This review discusses how the COVID-19 pandemic could increase the emergence of multidrug-resistant strains to currently available antibiotics. Initially, we discussed the spread and impact of multidrug resistance of ESKAPE pathogens associated with nosocomial infections and analyzed their risk of secondary infections in patients with COVID-19. Then we highlight three factors related to the spread of resistant bacteria during the current pandemic: overprescription of antibiotics followed by self-medication. Finally, we discussed the lack of availability of diagnostic tests to discriminate the etiologic agent of a disease. All these factors lead to inappropriate use of antibiotics and, therefore, to an increase in the prevalence of resistance, which can have devastating consequences shortly. The data compiled in this study underscore the importance of epidemiological surveillance of hospital isolates to provide new strategies for preventing and controlling infections caused by multidrug-resistant bacteria. In addition, the bibliographic research also highlights the need for an improvement in antibiotic prescribing in the health system.

Corynebacterium striatum-Got Worse by a Pandemic?

The role of Corynebacterium striatum has been demonstrated in different nosocomial infections. An increasing number of publications have demonstrated its virulence in the respiratory tract, especially in the immunosuppressed patient population. The number of these patients has increased significantly during the COVID-19 pandemic. For this reason, we aimed to investigate the prevalence and antimicrobial resistance pattern of this species between 2012 and 2021 at the Clinical Center of the University of Szeged, Hungary. Altogether, 498 positive samples were included from 312 patients during the study period. On the isolates, 4529 antibiotic susceptibility tests were performed. Our data revealed that the prevalence of C. striatum increased during the COVID-19 pandemic, the rise occurred in respiratory, blood culture, and superficial samples. During the study period, the rifampicin resistance significantly increased, but others have also changed dynamically, including linezolid. The species occurred with diverse and changing co-pathogens in the COVID-19 era. However, the increasing rifampicin and linezolid resistance of C. striatum was probably not due to the most commonly isolated co-pathogens. Based on resistance predictions, vancomycin is likely to remain the only effective agent currently in use by 2030.

Photodynamic therapy and combinatory treatments for the control of biofilm-associated infections

The advent of antimicrobial resistance has added considerable impact to infectious diseases both in the number of infections and healthcare costs. Furthermore, the relentless emergence of multidrug-resistant bacteria, particularly in the biofilm state, has made mandatory the discovery of new alternative antimicrobial therapies that are capable to eradicate resistant bacteria and impair the development of new forms of resistance. Amongst the therapeutic strategies for treating biofilms, antimicrobial photodynamic therapy (aPDT) has shown great potential in inactivating several clinically relevant micro-organisms, including antibiotic-resistant 'priority bacteria' declared by the WHO as critical pathogens. Its antimicrobial effect is centred on the basis that harmless low-intensity light stimulates a non-toxic dye named photosensitizer, triggering the production of reactive oxygen species upon photostimulation. In addition, combination therapies of aPDT with other antimicrobial agents (e.g. antibiotics) have also drawn considerable attention, as it is a multi-target strategy. Therefore, the present review highlights the recent advances of aPDT against biofilms, also covering progress on combination therapy.

Changes in resistance pattern of ESKAPE pathogens between 2010 and 2020 in the clinical center of University of Szeged, Hungary

The acronym ESKAPE stands for six antibiotic-resistant bacterial pathogens namely, Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp. Monitoring their resistance is an important task for clinical microbiology laboratories. Our aim was to analyze the resistance patterns of these bacteria over ten years in clinical samples of our department. We examined the sample types from which these pathogens were most frequently isolated. The incidence of tests with resistant results for each pathogen in aggregate and the most important subgroups of each was also analyzed. We have also intended to predict the local priorities amongst these pathogens. The results of 1,268,126 antibiotic susceptibility tests performed on a total of 70,099 isolates over this period were examined. Most strains were derived from urine, blood culture, trachea, vagina, wounds, and abscesses. Prevalence of ESKAPE bacteria increased between 2011 and 2020 however, the steepest intensifications were seen in the cases of K. pneumoniae and P. aeruginosa. The number of antibiotic susceptibility tests with resistant results has also increased over the decade but the most notable increase was detected in E. faecium and A. baumannii. Based on the calculation of antimicrobial resistance index for each pathogen, the most serious challenges for us at present are A. baumannii, P. aeruginosa, and E. faecium and their multi-resistant forms. The theoretical prediction of proportion of resistant tests between 2020 and 2030 in our care area draws attention to a worrying trend in the cases of vancomycin-resistant E. faecium and carbapenem-resistant A. baumannii strains.

Epidemiology of Escherichia coli Bacteremia: A Systematic Literature Review

BACKGROUND

Escherichia coli is the most common cause of bacteremia in high-income countries. To enable the development and implementation of effective prevention strategies, a better understanding of the current epidemiology of invasive E. coli infections is needed.

METHODS

A systematic review of literature published between 1 January 2007 and 31 March 2018 on the burden and epidemiology of E. coli bacteremia in populations that include adults in high-income countries was conducted. Meta-analysis was performed for descriptive purposes.

RESULTS

During the studied time interval, the estimated incidence rate of E. coli bacteremia was 48 per 100 000 person-years, but this increased considerably with age: rates per 100 000 person-years were >100 in 55-to-75-year-olds and >300 in 75-to-85-year-olds. Overall, E. coli accounted for 27% of documented bacteremia episodes: 18% if hospital acquired, 32% if community-onset healthcare associated, and 33% if community acquired. The estimated case fatality rate was 12%. Approximately 44% of episodes were community acquired, 27% community-onset healthcare associated, and 27% hospital acquired. Urinary tract infection (UTI) was the primary source for 53% of episodes.

CONCLUSIONS

This systematic review confirms the substantial burden of E. coli bacteremia in older adults and justifies the implementation of community-level programs to prevent E. coli bacteremia and ideally UTI in this age group.

Synergistic effect of antimicrobial peptide LL-37 and colistin combination against multidrug-resistant Escherichia coli isolates

Overview: The global spread of antibiotic resistance represents a serious threat for public health. Aim: We evaluated the efficacy of the antimicrobial peptide LL-37 as antimicrobial agent against multidrug-resistant Escherichia coli. Results: LL-37 showed good activity against mcr-1 carrying, extended spectrum β-lactamase- and carbapenemase-producing E. coli (minimum inhibitory concentration, MIC, from 16 to 64 mg/l). Checkerboard assays demonstrated synergistic effect of LL-37/colistin combination against all tested strains, further confirmed by time-kill and post antibiotic effect assays. MIC and sub-MIC concentrations of LL-37 were able to reduce biofilm formation. Conclusion: Our preliminary data indicated that LL-37/colistin combination was effective against multidrug-resistant E. coli strains and suggested a new possible clinical application.

In vitro antibacterial activity of ceftazidime/avibactam in combination against planktonic and biofilm carbapenemase-producing Klebsiella pneumoniae isolated from blood

OBJECTIVES

The aim of this study was to report on in vitro tests of antibacterial activity of ceftazidime/avibactam in combination against planktonic or biofilm KPC carbapenemase-producing Klebsiella pneumoniae (KPC-Kp), the rate of KPC-Kp blood isolates in University of Perugia Hospital over a 5-year period, and their antimicrobial susceptibility patterns.

METHODS

The antibacterial activity of ceftazidime/avibactam in combination with other antimicrobials was assessed against planktonic and biofilm bacteria by Etest and checkerboard assay. A retrospective review of laboratory data was performed to evaluate the rate of KPC-Kp from blood samples and their antimicrobial susceptibility patterns.

RESULTS

Between 2014 and 2019, 130/4241 (3.1%) KPC-Kp were identified from blood cultures. Their rate increased from 2.3% in 2014-2015 to 4.5% over the last 3 years. Overall, 4.6% (6/130) of KPC-Kp isolates were susceptible to meropenem, 65.4% (85/130) to colistin, 65.1% (84/129) to tigecycline, 34.6% (45/130) to amikacin, 36.2% (42/116) to gentamicin, 40.2% (39/97) to fosfomycin and 91.5% (65/71) to ceftazidime/avibactam. Five of six ceftazidime/avibactam-resistant KPC-Kp were isolated from patients not treated with ceftazidime/avibactam. Synergism was detected both by Etest and checkerboard assay for the combination of ceftazidime/avibactam plus meropenem against planktonic isolates, whilst lower bactericidal activity was observed in biofilm KPC-Kp isolates.

CONCLUSIONS

Our in vitro data suggest that the combination of ceftazidime/avibactam plus meropenem has a synergistic antibacterial activity against planktonic bacteria, whilst a lower activity was detected against biofilm, suggesting worse clinical outcomes whenever biofilm infections are present. Further analyses are required to confirm these results before extending them to clinical practice.

ESKAPE Pathogens in Bloodstream Infections Are Associated With Higher Cost and Mortality but Can Be Predicted Using Diagnoses Upon Admission

Background

ESKAPE bacteria are thought to be especially resistant to antibiotics, and their resistance and prevalence in bloodstream infections are rising. Large studies are needed to better characterize the clinical impact of these bacteria and to develop algorithms that alert clinicians when patients are at high risk of an ESKAPE infection.

Methods

From a US data set of >1.1 M patient encounters, we evaluated if ESKAPE pathogens produced worse outcomes than non-ESKAPE pathogens and if an ESKAPE infection could be predicted using simple word group algorithms built from decision trees.

Results

We found that ESKAPE pathogens represented 42.2% of species isolated from bloodstream infections and, compared with non-ESKAPE pathogens, were associated with a 3.3-day increase in length of stay, a $5500 increase in cost of care, and a 2.1% absolute increase in mortality (P < 1e-99). ESKAPE pathogens were not universally more resistant to antibiotics, but only to select antibiotics (P < 5e-6), particularly against common empiric therapies. In addition, simple word group algorithms predicted ESKAPE pathogens with a positive predictive value of 7.9% to 56.2%, exceeding 4.8% by random guessing (P < 1e-99).

Conclusions

Taken together, these data highlight the pathogenicity of ESKAPE bacteria, potential mechanisms of their pathogenicity, and the potential to predict ESKAPE infections upon admission. Implementing word group algorithms could enable earlier and targeted therapies against ESKAPE bacteria and thus reduce their burden on the health care system.

Synthesis, Docking Studies, and In Vitro Evaluation of Some Novel Thienopyridines and Fused Thienopyridine-Quinolines as Antibacterial Agents and DNA Gyrase Inhibitors

A series of novel thienopyridines and pyridothienoquinolines (3a,b–14) was synthesized, starting with 2-thioxo-1,2-dihydropyridine-3-carbonitriles 1a and 1b. All compounds were evaluated for their in vitro antimicrobial activity against six bacterial strains. Compounds 3a,b, 4a, 5b, 6a,b, 7a, 9b, 12b, and 14 showed significant growth inhibition activity against both Gram-positive and Gram-negative bacteria compared with the reference drug. The most active compounds (4a, 7a, 9b, and 12b) against Staphylococcus aureus were also tested for their in vitro inhibitory action on methicillin-resistant Staphylococcus aureus (MRSA). The tested compounds showed promising inhibition activity, with the performance of 12b being equal to gentamicin and that of 7a exceeding it. Moreover, the most promising compounds were also screened for their Escherichia coli DNA gyrase inhibitory activity, compared with novobiocin as a reference DNA gyrase inhibitor. The results revealed that compounds (3a, 3b, 4a, 9b, and 12b) had the highest inhibitory capacity, with IC₅₀ values of 2.26–5.87 µM (that of novobiocin is equal to 4.17 µM). Docking studies were performed to identify the mode of binding of the tested compounds to the active site of E. coli DNA gyrase B.