Proposed amendments regarding the definitions of multidrug-resistant and extensively drug-resistant bacteria

Multidrug-resistant phenotypes of genetically diverse Escherichia coli isolates from healthy domestic cats

Β-lactamases-producing Escherichia coli are a widely distributed source of antimicrobial resistance (AMR), for animals and humans. Little is known about the sensitivity profile and genetic characteristics of E. coli strains isolated from domestic cats. We report a cross-sectional study that evaluated E. coli strains isolated from domestic cats in Panama. For this study the following antibiotics were analyzed: ampicillin, amoxicillin-clavulanate cefepime, cefotaxime, cefoxitin, ceftazidime, aztreonam, imipenem, gentamicin, kanamycin, streptomycin, tetracycline, ciprofloxacin, nalidixic acid, trimethoprim-sulfamethoxazole, and chloramphenicol. The data obtained were classified as resistant, intermediate, or sensitive. MDR strains were established when the strain presented resistance to at least one antibiotic from three or more antimicrobial classes. Forty-eight E. coli isolates were obtained, of which 80% presented resistance to at least one of the antibiotics analyzed, while only 20% were sensitive to all (p = 0.0001). The most common resistance was to gentamicin (58%). Twenty-nine percent were identified as multidrug-resistant isolates and 4% with extended spectrum beta-lactamase phenotype. The genes blaTEM (39%), blaMOX(16%), blaACC (16%) and blaEBC (8%) were detected. Plasmid-mediated resistance qnrB (25%) and qnrA (13%) are reported. The most frequent sequence types (STs) being ST399 and we reported 5 new STs. Our results suggest that in intestinal strains of E. coli isolated from domestic cats there is a high frequency of AMR.

Peptide Dendrimer-Based Antibacterial Agents: Synthesis and Applications

Pathogenic bacteria cause the deaths of millions of people every year. With the development of antibiotics, hundreds and thousands of people's lives have been saved. Nevertheless, bacteria can develop resistance to antibiotics, rendering them insensitive to antibiotics over time. Peptides containing specific amino acids can be used as antibacterial agents; however, they can be easily degraded by proteases in vivo. To address these issues, branched peptide dendrimers are now being considered as good antibacterial agents due to their high efficacy, resistance to protease degradation, and low cytotoxicity. The ease with which peptide dendrimers can be synthesized and modified makes them accessible for use in various biological and nonbiological fields. That is, peptide dendrimers hold a promising future as antibacterial agents with prolonged efficacy without bacterial resistance development. Their in vivo stability and multivalence allow them to effectively target multi-drug-resistant strains and prevent biofilm formation. Thus, it is interesting to have an overview of the development and applications of peptide dendrimers in antibacterial research, including the possibility of employing machine learning approaches for the design of AMPs and dendrimers. This review summarizes the synthesis and applications of peptide dendrimers as antibacterial agents. The challenges and perspectives of using peptide dendrimers as the antibacterial agents are also discussed.

Rare Cases of Pseudomonas aeruginosa Meningitis in Children: 10-Year Experience in a Single Center

OBJECTIVE

The primary objective was to elucidate the epidemiologic characteristics, risk determinants, and clinical outcomes associated with Pseudomonas aeruginosa-induced meningitis.

METHODS

All cases of meningitis caused by Pseudomonas aeruginosa that were treated at the hospital between 2012 and 2022 were retrospectively analyzed and detailed.

RESULTS

During a 10-year period, only 10 patients satisfied the inclusion criteria. Three patients had previously undergone neurosurgical procedures and 4 patients had leukemia.

CONCLUSIONS

Although Pseudomonas aeruginosa meningitis possesses a low incidence rate, the rate of mortality is high. Patients with leukemia or those who have undergone neurosurgery are the most susceptible to diagnosis. Cases of severe neutropenia present only mild or no cerebrospinal fluid pleocytosis. In patients with sensitive Pseudomonas aeruginosa meningitis, the timely use of anti-Pseudomonas carbapenems for intravenous treatment is highly effective. For drug-resistant Pseudomonas aeruginosa meningitis, intrathecal polymyxins administration can be an effective treatment option.

Bacteriophages for Controlling Staphylococcus spp. Pathogens on Dairy Cattle Farms: In Vitro Assessment

Pathogenic Staphylococcus spp. strains are significant agents involved in mastitis and in skin and limb infections in dairy cattle. The aim of this study was to assess the antibacterial effectiveness of bacteriophages isolated from dairy cattle housing as potential tools for maintaining environmental homeostasis. The research will contribute to the use of phages as alternatives to antibiotics. The material was 56 samples obtained from dairy cows with signs of limb and hoof injuries. Staphylococcus species were identified by phenotypic, MALDI-TOF MS and PCR methods. Antibiotic resistance was determined by the disc diffusion method. Phages were isolated from cattle housing systems. Phage activity (plaque forming units, PFU/mL) was determined on double-layer agar plates. Morphology was examined using TEM microscopy, and molecular characteristics were determined with PCR. Among 52 strains of Staphylococcus spp., 16 were used as hosts for bacteriophages. Nearly all isolates (94%, 15/16) showed resistance to neomycin, and 87% were resistant to spectinomycin. Cefuroxime and vancomycin were the most effective antibiotics. On the basis of their morphology, bacteriophages were identified as class Caudoviricetes, formerly Caudovirales, families Myoviridae-like (6), and Siphoviridae-like (9). Three bacteriophages of the family Myoviridae-like, with the broadest spectrum of activity, were used for further analysis. This study showed a wide spectrum of activity against the Staphylococcus spp. strains tested. The positive results indicate that bacteriophages can be used to improve the welfare of cattle.

Traditional and new proposals for environmental microbial indicators-a review

The continuous increment in world population coupled with the greatest natural resource consumption and waste generation has an enormous impact on the environment. To date, using biological indicators (bioindicators) to evaluate the biological quality of natural environments is very common. Nonetheless, selecting those suitable for each ecosystem or contaminant is one of the most important issues for environmental sciences. Bacteria and helminths are mainly related to fecal contamination, while antibiotic-resistant bacteria, fungi, viruses, and microalgae are organisms used to determine deteriorated ecosystems by diverse contaminants. Nowadays, each bioindicator is used as a specific agent of different contaminant types, but detecting and quantifying these bioindicator microorganisms can be performed from simple microscopy and culture methods up to a complex procedure based on omic sciences. Developing new techniques based on the metabolism and physiological responses of traditional bioindicators is shown in a fast environmental sensitivity analysis. Therefore, the present review focuses on analyzing different bioindicators to facilitate developing suitable monitoring environmental systems according to different pollutant agents. The traditional and new methods proposed to detect and quantify different bioindicators are also discussed. Their vital role is considered in implementing efficient ecosystem bioprospection, restoration, and conservation strategies directed to natural resource management.

Antimicrobial Resistance in Bacteria from Meat and Meat Products: A One Health Perspective

According to the 2030 Agenda of the United Nations, one of the sustainable development goals is to ensure sustainable consumption and production patterns. The need to ensure food safety includes, other than microbiological hazards, concerns with antimicrobial-resistant (AMR) bacteria. The emergence of resistant bacteria in the food industry is essentially due to the abusive, and sometimes incorrect, administration of antimicrobials. Although not allowed in Europe, antimicrobials are often administered to promote animal growth. Each time antimicrobials are used, a selective pressure is applied to AMR bacteria. Moreover, AMR genes can be transmitted to humans through the consumption of meat-harbouring-resistant bacteria, which highlights the One Health dimension of antimicrobial resistance. Furthermore, the appropriate use of antimicrobials to ensure efficacy and the best possible outcome for the treatment of infections is regulated through the recommendations of antimicrobial stewardship. The present manuscript aims to give the current state of the art about the transmission of AMR bacteria, particularly methicillin-resistant S. aureus, ESBL-producing Enterobacteriaceae, and vancomycin-resistant Enterococcus spp., along with other ESKAPE bacteria, from animals to humans through the consumption of meat and meat products, with emphasis on pork meat and pork meat products, which are considered the most consumed worldwide.

Prevalence and Antimicrobial Susceptibility Profile of Salmonella and Shigella among Diarrheic Patients Attending Selected Health Facilities in Addis Ababa, Ethiopia

Diarrhea is one of the important public health problems in developing countries. Salmonella and Shigella species are the major bacterial causal agents of diarrhea. The increasing burden of antimicrobial resistance is posing difficulty in the treatment of these pathogens. This study aimed to assess the occurrence of Salmonella and Shigella in the feces of diarrheic patients receiving health services in Addis Ababa, Ethiopia, and to determine their antimicrobial susceptibility profile. A cross-sectional study involving 13 health centers was conducted where 428 diarrheic patients were recruited. Standard microbiology techniques were used to isolate Salmonella and Shigella from stool samples. In addition, Salmonella isolates were confirmed by polymerase chain reaction (PCR). The Kirby-Bauer disc diffusion method was employed to assess susceptibility to 11 antimicrobials for each of the Salmonella and Shigella isolates. The prevalence of Salmonella and Shigella spp. among diarrheic patients was 8.4%; n = 36 and 5.6%; n = 24, respectively. Thirty (83.3%) of Salmonella isolates were susceptible to all antimicrobials tested, whereas 4 (10.8%) of isolates were resistant to 2 or more antimicrobials and 2 (5.6%) were multidrug resistant. Resistance to ampicillin was recorded in only one (2.7%) of Salmonella isolates; however, resistance to ampicillin was recorded in 12 (50%) of the Shigella isolates. Half of the Shigella isolates (n = 12) were resistant to 2 or more antimicrobials while 5 (20.8%) of them were resistant to 3 or more antimicrobials. The overall rate of resistance to antimicrobials was more common in Shigella compared to Salmonella isolates. In conclusion, Salmonella and Shigella were isolated from the feces of diarrheic patients, with a higher rate of antimicrobial resistance in Shigella isolates, which could make the treatment of shigellosis challenging. Therefore, increasing hygienic practices during food preparation to reduce the burden of Salmonella and Shigella infection and prudent use of antimicrobials are recommended to limit the spread of antimicrobial resistant strains.

Potential of Natural Phenolic Compounds as Antimicrobial Agents against Multidrug-Resistant Staphylococcus aureus in Chicken Meat

Staphylococcus aureus is one of the most widespread foodborne bacteria that cause high morbidity, mortality, and economic loss, primarily if foodborne diseases are caused by pathogenic and multidrug-resistant (MDR) strains. This study aimed to determine the prevalence of S. aureus in chicken meat in Egyptian markets. Thus, this study might be the first to assess the efficiency of different natural phenolic compounds as novel antibacterial agents against MDR S. aureus pathogens isolated from raw chicken meat in the Egyptian market. The incidence and quantification of pathogenic S. aureus were detected in retail raw chicken meat parts (breast, thigh, fillet, and giblets). In total, 73 out of 80 (91.3%) of the chicken meat parts were contaminated, with S. aureus as the only species isolated. Of the 192 identified S. aureus isolates, 143 were coagulase-positive S. aureus and 117 isolates were MDR (81.8%, 117/143). Twenty-two antibiotic resistance profile patterns were detected. One strain was randomly selected from each pattern to further analyze virulence and resistance genes. Extracted DNA was assessed for the presence of antibiotic-resistance genes, i.e., vancomycin-resistance (vanA), aminoglycosides-resistance (aacA-aphD), apramycin-resistance (apmA), and methicillin-resistance (mecA), penicillin-resistance (blaZ), and virulence genes staphylococcal enterotoxins (sea and seb), Panton-Valentine leucocidin (pvl), clumping factor A (clfA), and toxic shock syndrome toxin (tst). Clustering analyses revealed that six S. aureus strains harbored the most virulence and resistance genes. The activity of hydroquinone was significantly higher than thymol, carvacrol, eugenol, and protocatechuic acid. Therefore, phenolic compounds, particularly hydroquinone, could potentially alternate with conventional antibiotics against the pathogenic MDR S. aureus inhabiting raw chicken meat. Hence, this study indicates that urgent interventions are necessary to improve hygiene for safer meat in Egyptian markets. Moreover, hydroquinone could be a natural phenolic compound for inhibiting foodborne pathogens.

Analysis on Bacterial Distribution and Change of Drug Resistance Rate in ICUs Across Southwest China from 2018 to 2022

Purpose

To analyze the distribution of bacteria and their drug resistance changes in Intensive Care Units (ICUs) across Southwest China from 2018 to 2022 and establish the antibiogram in this region to provide a basis for early empirical antimicrobial use.

Methods

Non-repetitive pathogens isolated from 109 member units with qualified data were obtained from the Antimicrobial Resistance Surveillance System in Sichuan Province, southwest China. The results obtained were interpreted with reference to CLSI M100-31th, and analyzed with WHONET 5.6 software.

Results

A total of 46,728 clinical isolates in ICUs were collected from 2018 to 2022, of which gram-negative organisms accounted for 76.1%, and gram-positive were 23.9%. The top 5 were Klebsiella pneumoniae, Acinetobacter baumannii, Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus, respectively. From 2018 to 2022, the resistance rates of Klebsiella pneumoniae to imipenem and meropenem changed from 14.5% and 17.8% to 14.0% and 14.4%, showing a steady downward trend. Escherichia coli was always highly sensitive to carbapenems, with a total resistance rate of 3.8%. Among non-fermented gram-negative bacteria, the resistance rates of Pseudomonas aeruginosa to imipenem and meropenem decreased significantly, changed from 25.3% and 22.9% in 2018 to 20.0% and 15.1% in 2022. However, Acinetobacter baumannii showed high resistance rates of 76.2% and 76.9% to imipenem and meropenem, respectively. MRSA and MRCNS accounted for 31.7% and 82.7%, respectively. No vancomycin and linezolid-resistant Staphylococcus aureus was isolated. Enterococcus faecalis maintained high activity to vancomycin, teicoplanin, and linezolid; no vancomycin or teicoplanin-resistant Enterococcus faecium strains were detected.

Conclusion

From 2018 to 2022, the isolated bacteria in ICU were mainly gram-negative bacteria, and the growth of some multidrug-resistant bacteria was effectively controlled. All levels of medical institutions should continue to strengthen bacterial resistance surveillance, promote the establishment of antimicrobial stewardship program, and enhance restrictions on outpatient antimicrobial use.

The Etiological and Drug Resistance Characteristics of Multidrug-Resistant Pathogens in Patients Requiring Extracorporeal Membrane Oxygenation: A Retrospective Cohort Study

Purpose

Infections induced by multidrug-resistant (MDR) pathogens are one of the most common and serious complications in extracorporeal membrane oxygenation (ECMO) patients. However, there is currently little research about "ECMO and MDR bacteria". The purpose of our study was to clarify the epidemiological characteristics of MDR bacteria and provide references for empiric antibiotic treatments according to the drug susceptibility tests for ECMO patients.

Patients and Methods

There were 104 patients admitted to our department and receiving ECMO treatments between January 2014 and December 2022. Altogether, 61 veno-arterial ECMO (VA-ECMO) and 29 veno-venous ECMO (VV-ECMO) patients enrolled. The data on other intensive care unit (ICU) patients in our department in the same period are summarized.

Results

A total of 82 MDR bacteria were detected from ECMO patients, and most of these were MDR Gram-negative bacteria (MDR-GNB). There were also 5559 MDR-GNB collected from other patients in our department in the same period. We found that the distribution of MDR-GNB in ECMO patients was different from other critical patients. The proportion of Klebsiella pneumoniae (MDR-KP) in VV-ECMO patients was higher than other critical patients (35.1% and 21.3%, respectively). Moreover, the proportions of MDR Acinetobacter baumannii (MDR-AB) of VA-ECMO and VV-ECMO were higher than other critical patients (54.6%, 43.2% and 30.5%, respectively). In addition, MDR-AB and MDR-KP in ECMO patients exhibited higher percentages of drug resistance to possibly appropriate antibiotics for other critical patients, but showed better sensitivity to colistin.

Conclusion

Infections induced by MDR-GNB in ECMO patients were serious and exhibited higher degrees of drug resistance compared with other ICU patients. Colistin might be an option to consider if there is no medical contraindication. However, widespread use of broad spectrum antibiotics is something that should be discouraged, and alternative options are being explored.

An overview of gram-negative bacteria with difficult-to-treat resistance: definition, prevalence, and treatment options

INTRODUCTION

Difficult-to-treat resistance (DTR) is a newly proposed resistance phenotype characterized by resistance to all first-line drugs. The emergence of DTR as a new resistance phenotype has significant implications for clinical practice. This new concept has the potential to be widely used instead of traditional phenotypes.

AREAS COVERED

This study carried out a detailed analysis about the definition, application, and evolution of various resistance phenotypes. We collected all the research articles on Gram-negative bacteria with difficult-to-treat resistance (GNB-DTR), analyzed the DTR in each region and each bacterial species. The advantages and doubts of DTR, the dilemma of GNB-DTR infections and the potential therapeutic strategies are summarized in the review.

EXPERT OPINION

Available studies show that the prevalence of GNB-DTR is not optimistic. Unlike traditional resistance phenotypes, DTR is more closely aligned with the clinical treatment perspective and can help with the prompt selection of an appropriate treatment plan. Currently, potential treatment options for GNB-DTR include a number of second-line drugs and novel antibiotics. However, the definition of first-line drugs is inherently dynamic. Therefore, the DTR concept based on first-line drugs needs to be continuously updated and refined, considering the emergence of new antibiotics, resistance characteristics, and pathogen prevalence in different regions.

Prevalence of Multidrug-Resistant Pathogens Causing Neonatal Early and Late Onset Sepsis, a Retrospective Study from the Tertiary Referral Children's Hospital

Introduction

Sepsis is the most severe infectious disease with the highest mortality rate, particularly among neonates admitted to the neonatal intensive care unit (NICU). This study retrospectively analyzed the epidemiology, antibiotic resistance profiles, and prevalence of multidrug-resistant (MDR) bacteria isolated from blood or cerebrospinal fluid (CSF) cultures in order to evaluate the appropriateness of initial empirical therapy for neonatal sepsis.

Methods

A retrospective study was conducted in the NICU from January 1, 2015, to December 31, 2022. Microbiological data from patients admitted to the NICU were anonymously extracted from the Laboratory of Microbiology database. Neonatal sepsis was classified into two types: early-onset sepsis (EOS), which occurs within the first 72 hours of life, and late-onset sepsis (LOS) for those begins later.

Results

A total of 679 bacterial strains, 543 from blood and 136 from CSF, were detected in 631 neonates. Among these, 378 isolates (55.67%) were Gram-positive bacteria, and 301 isolates (44.33%) were Gram-negative bacteria. The most frequently isolated pathogens were Coagulase-negative staphylococci (CoNS) (36.52%), followed by Klebsiella pneumoniae (20.47%) and Escherichia coli (13.84%). In EOS, 121 strains were found, CoNS represented the majority (33.88%), followed by Klebsiella pneumoniae (23.97%) and Escherichia coli (8.26%). Early-onset septicemia exhibited 67 (55.37%) MDR bacteria. In LOS, 558 strains were isolated, CoNS represented the majority of pathogens (37.10%), followed by Klebsiella pneumoniae (19.71%) and Escherichia coli (15.05%). Late-onset septicemia showed 332 (59.50%) MDR bacteria. High rates of MDR were found in CoNS (76.21%), carbapenem-resistant Klebsiella pneumoniae (66.91%), and MRSA (33.33%).

Conclusion

The study revealed an alarming prevalence of MDR strains isolated from neonatal sepsis, emphasizing the necessity of finding effective prevention and treatment measures. Colistin can be used for MDR Gram-negative bacteria, while vancomycin and teicoplanin can be considered treatment therapies for staphylococcal infections.

The Impact of COVID-19 Pandemic on ESBL-Producing Enterobacterales Infections: A Scoping Review

Several studies have reported an increased frequency of colonization and/or infection with antibiotic-resistant bacteria (ARB) during the COVID-19 pandemic. Extended-spectrum beta-lactamase-producing Enterobacterales (ESBL-PE) are a group of bacteria with intrinsic resistance to multiple antibiotics, including penicillins, cephalosporins, and monobactams. These pathogens are easy to spread and can cause difficult-to-treat infections. Here, we summarize the available evidence on the impact of the COVID-19 pandemic on infections caused by ESBL-PE. Using specific criteria and keywords, we searched PubMed, MEDLINE, and EMBASE for articles published up to 30 March 2023 on potential changes in the epidemiology of ESBL-E since the beginning of the COVID-19 pandemic. We identified eight studies that documented the impact of COVID-19 on ESBL-E. Five studies were focused on assessing the frequency of ESBL-PE in patient-derived specimens, and three studies investigated the epidemiological aspects of ESBL-PE infections in the context of the COVID-19 pandemic. Some of the studies that were focused on patient specimens reported a decrease in ESBL-PE positivity during the pandemic, whereas the three studies that involved patient data (1829 patients in total) reported a higher incidence of ESBL-PE infections in patients hospitalized for COVID-19 compared with those with other conditions. There are limited data on the real impact of the COVID-19 pandemic on the epidemiology of ESBL-PE infections; however, patient-derived data suggest that the pandemic has exacerbated the spread of these pathogens.

Susceptibility antibiotic screening reveals high rates of multidrug resistance of Salmonella, Shigella and Campylobacter in HIV infected and uninfected patients from Mozambique

BACKGROUND

Antibacterial resistance is a growing concern worldwide, including in Mozambique. Diarrhea is an important cause of mortality in Mozambique, yet few local studies have reported on the resistance of bacterial pathogens in this context. Therefore, this study aims to characterize antibiotic susceptibility patterns of Salmonella, Shigella and Campylobacter spp. among patients with diarrhea, including those who are HIV-infected and-uninfected.

METHODS

We conducted antibiotic susceptibility testing on 157 stool isolates recovered from 129 patients aged between 0 and 80 years with diarrhea, including HIV infected (n = 68) and-uninfected individuals (n = 61), assisted at two health centers in Maputo city. The isolates comprised of 99 Salmonella, 45 Shigella and 13 Campylobacter strains. The Kirby-Bauer disk diffusion method was used on Mueller-Hinton II agar for Salmonella and Shigella spp., while Mueller-Hinton II agar with 5% defibrinated sheep blood was used for Campylobacter spp. We tested six antibiotics listed on the national essential medicines list, including ciprofloxacin, erythromycin, azithromycin, trimethoprim-sulfamethoxazole, gentamicin, and tetracycline.

RESULTS

All isolates were resistant to at least one antibiotic. A high percentage of Salmonella spp. isolates were found to be resistant to trimethoprim-sulfamethoxazole (89.9%, n = 89), erythromycin (88.9%, n = 88) and tetracycline (76.8%, n = 76). In addition, 86.6% (n = 39) and 68.9% (n = 31) of Shigella isolates were resistant to trimethoprim-sulfamethoxazole and tetracycline, respectively. The majority of Campylobacter isolates (92.3%, n = 12) were resistant to erythromycin, azithromycin and tetracycline. Multidrug resistance (MDR) was observed in 79.8% of Salmonella spp., 76.9% of Campylobacter spp., and 57.8% of Shigella spp. Drug susceptibility profiles for Salmonella spp. and Campylobacter were similar in both HIV-1 infected and uninfected patients. However, Shigella spp. isolates obtained from patients without HIV infection were significantly more likely to be resistant to erythromycin, azithromycin or to exhibit multidrug resistance than those obtained from patients with HIV-1 infection (p < 0.05). All Shigella spp. and Campylobacter spp. isolates were susceptible to gentamicin.

CONCLUSION

Our study highlights concerning rates of antibiotic resistance and MDR among diarrheal bacterial pathogens in Mozambique. Further research is needed to understand the impact of HIV, ART therapy and immunosuppression on antibiotic resistance. Urgent interventions are essential to prevent the spread of resistant strains.

Bacterial Isolates from Urinary Tract Infection in Dogs and Cats in Portugal, and Their Antibiotic Susceptibility Pattern: A Retrospective Study of 5 Years (2017-2021)

There are growing concerns regarding the rise of antimicrobial-resistant bacteria in companion animals. This study aimed to bring new insights into the current scenario of Portugal's antimicrobial resistance bacteria isolated from companion animals with urinary tract infections and is the first to be performed during a long period on a large scale. Of a total of 17472 urine samples analyzed, 12,166 (69.6%) (CI 12,200-12,200) were negative for bacterial growth, and 5306 (30.4%) (95% CI 5310-5310) had bacterial growth. Of the culture-positive samples, 5224 (96.6%) (95% CI 5220-5220) were pure cultures and 82 (3.2%) (95% CI 81.9-82.1) had mixed growth. Escherichia coli was the most frequently isolated bacteria (n=2360, 44.5%) (95% CI 2360-2360), followed by Proteus mirabilis (n=585, 11%) (95% CI 583-583), Enterococcus faecium (n=277, 5.2%) (95% CI 277-277) and Staphylococcus pseudintermedius (n=226, 4.3%) (95% CI 226-226). The overall susceptibility rates were low for erythromycin (45.3%) and clindamycin (51.3%), and high for aminoglycosides (96.3%), carbapenems (92.4%), trimethoprim-sulfamethoxazole (81.2%), and quinolones (79.9%). E. coli also showed considerable resistance to amoxicillin-clavulanic acid. The rates of multidrug-resistant bacteria are still high compared to the northern countries of Europe. This study's findings show the emergence of antibiotic resistance in the antibiotic agents commonly used in the treatment of UTIs in dogs and cats in Portugal.

Antibiotic Resistance in Bacteria—A Review

Background: A global problem of multi-drug resistance (MDR) among bacteria is the cause of hundreds of thousands of deaths every year. In response to the significant increase of MDR bacteria, legislative measures have widely been taken to limit or eliminate the use of antibiotics, including in the form of feed additives for livestock, but also in metaphylaxis and its treatment, which was the subject of EU Regulation in 2019/6. Numerous studies have documented that bacteria use both phenotypis and gentic strategies enabling a natural defence against antibiotics and the induction of mechanisms in increasing resistance to the used antibacterial chemicals. The mechanisms presented in this review developed by the bacteria have a significant impact on reducing the ability to combat bacterial infections in humans and animals. Moreover, the high prevalence of multi-resistant strains in the environment and the ease of transmission of drug-resistance genes between the different bacterial species including commensal flora and pathogenic like foodborne pathogens (E. coli, Campylobacter spp., Enterococcus spp., Salmonella spp., Listeria spp., Staphylococcus spp.) favor the rapid spread of multi-resistance among bacteria in humans and animals. Given the global threat posed by the widespread phenomenon of multi-drug resistance among bacteria which are dangerous for humans and animals, the subject of this study is the presentation of the mechanisms of resistance in most frequent bacteria called as “foodborne pathoges” isolated from human and animals. In order to present the significance of the global problem related to multi-drug resistance among selected pathogens, especially those danger to humans, the publication also presents statistical data on the percentage range of occurrence of drug resistance among selected bacteria in various regions of the world. In addition to the phenotypic characteristics of pathogen resistance, this review also presents detailed information on the detection of drug resistance genes for specific groups of antibiotics. It should be emphasized that the manuscript also presents the results of own research i.e., Campylobacter spp., E. coli or Enetrococcus spp. This subject and the presentation of data on the risks of drug resistance among bacteria will contribute to initiating research in implementing the prevention of drug resistance and the development of alternatives for antimicrobials methods of controlling bacteria.

Potential Bioactive Compounds from Marine Streptomyces sp. and Their In Vitro Antibiofilm and Antibacterial Activities Against Antimicrobial-Resistant Clinical Pathogens

Antimicrobial resistance issues have risen dramatically in recent years, posing a severe concern to humans worldwide. The urgent need to find novel compounds for pharmaceutical applications prompts the research of under-explored environments such as marine ecosystems. The present study was designed to discover novel secondary metabolites, and we have isolated about 30 actinomycetes from the marine soil samples collected in Thondi (Ramanathapuram, Tamil Nadu, India), where most isolates are associated with the genus Streptomyces. Out of 30, one potentially active strain (Streptomyces sp. SRMA3) was identified using primary and secondary screening methods against the drug-resistant clinical pathogens. The active metabolites extracted from the selected active isolate were subjected to partial purification and characterization using Fourier transform infrared spectrophotometer (FTIR) and gas chromatography-mass spectroscopy (GC-MS) analysis. The minimum inhibitory concentration (MIC) value was determined for the active metabolite. Further, the partially purified active fraction was revealed for its antibacterial and antibiofilm activity against drug-resistant clinical pathogens. Light and fluorescence microscopy detected the viability and adhesion of the biofilm-forming drug-resistant pathogens. Growth curve analysis showed that the active metabolite has the potential to inhibit drug-resistant pathogens. The synergistic effect of active metabolite with commercial antibiotics also revealed that it could enhance the activity of antibiotics in antimicrobial resistance pathogens. This study shows that the isolated Streptomyces sp. SRMA3 is a potentially active strain, and the metabolite derived from this strain has a good antibacterial and antibiofilm activity against antimicrobially resistant clinical pathogens and could be used for various biotechnological applications.

Antibacterial Activity of Solanum torvum Leaf Extract and Its Synergistic Effect with Oxacillin against Methicillin-Resistant Staphyloccoci Isolated from Dogs

Methicillin-resistant staphylococci (MRS) have been considered a veterinary and public health threat that needs to be addressed, as they are known to cause serious infections, with limited therapeutic options. Thus, in this study, we aimed to examine the potential antibacterial activity of the leaf extract of Solanum torvum against MRS isolated from clinically healthy dogs. In total, seven mecA-positive Staphylococcus isolates tested in this study were identified using 16S rRNA gene sequencing, and all of them were classified as multidrug-resistant using disk diffusion tests. According to gas chromatography-mass spectrometry analysis, the main phytochemical components found in the leaf extract were hexadecanoic acid and its ethyl ester and 9,12,15-octadecatrienoic acid, ethyl ester, (Z,Z,Z). The minimum inhibitory concentration (MIC) breakpoints for the leaf extract against all tested isolates ranged from 2 to 16 mg/mL, while the MIC breakpoints for oxacillin were from 2 to 512 mg/L. Although varying effects were found, the positive effects of the leaf extract were most evident in combination with oxacillin. These results suggested that S. torvum leaf extract may complement classical antibiotics and may potentially drive the development of an effective therapeutic option for MRS.