Chronic wounds (CW) are growing rapidly, affecting 1–2% of the world's population, imposing a huge burden on healthcare systems and (urgently) needing dressings capable of aiding a more effective healing process. Infection is a complex problem in CW, and it is also known that wounds with intense bleeding prevent a rapid response, often resulting in patient morbidity and mortality.

Polycaprolactone (PCL) is a synthetic, biodegradable, biocompatible polymer, with elastic performance and excellent mechanical properties. On the other hand, sodium alginate (SA) is also a biocompatible, biodegradable and non-toxic polymer capable of retaining large amounts of water. Here, a flexible and non-adhesive fibrous structure (made of hydrophobic components that limit blood loss), easily recognized by the skin's extracellular matrix (which fibrous architecture is organized in a similar way), and loaded with hemostatic agents (carbon nanofibers, CNFs) and antibiotics (ceftazidime), was engineered for overcoming the previous problems and promote rapid blood clotting, and consequent tissue regeneration.

Wet-spun coaxial fibers were produced with a shell made of 10 wt.% PCL modified with CNFs (50, 100, 150 μg/mL) and a core of 2 wt.% SA loaded with Ceftazidime (128 μg/mL) using a 2 wt.% CaCl₂ coagulation bath. The coaxial structure was confirmed via brightfield microscopy, and the elements composing the fibers were detected by Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric analyses (TGA). Antimicrobial testing was conducted against Staphylococcus aureus and Pseudomonas aeruginosa revealing great efficacy over a period of 24h. The ability of the fibers to induce blood coagulation was verified using recalcified plasma. In the end, the coaxial fibers were identified as potentially effective for CW care.

The prevalence of resistance to antibiotics of uropathogenic bacteria constitute a very major health problem and it is the subject of much research. The inhibition of the uropathogenic bacteria by lactic acid bacteria is the subject of a number of studies. In this study, we evaluate the resistance, the multi-resistance and the susceptibility of some bacteria isolated from contaminated urine and their inhibition by three lactic acid bacteria isolated from feed: Enterococcus faecium CM9, Enterococcus faecium H3 and Lactobacillus brevis LBM2.

Methods. The evaluation of the resistance to antibiotics of uropathogenic bacteria was evaluated by the Vitek 2 Compact using an adequate card and were performed as the standard procedure. The inhibition of the uropathogenic bacteria by the lactic acid bacteria strains was performed using the streak agar test described by Ayeni et al. (2009).

Results. Ten uropathogenic strains from urine samples from patients with urinary tract infections were isolated, it's about: Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Serratia marcescens, Staphylococcus aureus, Staphylococcus saprophyticus, Sterptococcus agalactiae, Entrobacter cloacae. The antibiogram test expressed by Vitek 2 Compact revealed that Klebsiella pneumoniae was the most resistant to antibiotics, while Escherichia coli was the most sensitive. The study also showed that three lactic strains Lactobacillus brevis LBM2, Enterococcus faecium CHM9 and H2.3 had strong antimicrobial activity against Gram-positive and Gram-negative uropathogen bacteria.

Introduction. Staphylococcus aureus is a spherically clustered Gram-positive bacterium pathogenic to humans and animals. Normally, S. aureus can be isolated from healthy individuals from the nose, pharynx, and skin, although it is rare for it to cause infections in healthy skin, however, upon entering tissues or the bloodstream, it can cause serious diseases, in this regard, S. aureus is one of the main reasons for the spread of hospital and community infections. Methicillin-resistant S. aureus (MRSA) strains were first observed among clinical isolates from hospitalized patients in the 1960s, but since the 1990s they have spread rapidly in the community. The objective of this work is to study the resistance to antibiotics of MRSA strains isolated from the Mexican population.

Methods. Pharyngeal and nasal swabs were performed in 1777 apparently healthy people from the Mexican population from 1999 to 2011 with a mean age of 22.91 years (±16.9). The exudates were inoculated on Salt and mannitol agar until isolates were obtained. Mannitol and coagulase-positive fermenting strains were considered as S. aureus. The minimum inhibitory concentration (MIC) test for oxacillin was performed on these strains, and they were considered as MRSA to those strains that grew in concentrations ≥4 µg/µL. Antibiogram test was performed on all strains using the Kirby-Bauer method for antibiotics: ciprofloxacin (CIP), fosfomycin (FO), trimethoprim-sulfamethoxazole (TSX), penicillin (P), vancomycin (VA), tetracycline (TE), erythromycin (E), oxacillin (OX), macrolides (MAC), clindamycin (CC), gentamicin (GM), and cephalothin (CF).

Results. 87 methicillin-resistant Staphylococcus aureus (MRSA) carriers (5%) were found, of which 21 are carriers in both anatomical sites (1.2%), 35 are MRSA carriers exclusively in the nose (2%) and 31 MRSA carriers. exclusive in pharynx (1.8%), having a total of 108 MRSA strains. The antibiotic to which the S. aureus strains show the greatest resistance is P (96 strains - 88.9%), followed by CC (67 strains - 62%), E (33 strains - 30.5%), OX (22 strains - 20.4 %), TE (18 strains – 16.7%), CIP, FO and VA (10 strains – 9.2%), CF (7 strains – 6.5%), GM (6 strains – 5.5%), TSX (3 strains – 2.8% ) and finally MAC (2 strains – 1.9%). In this sense, 25 strains only present resistance to one antibiotic (P) (23.1%), 40 strains are resistant to 2 antibiotics (37%), 18 have resistance to 3 antibiotics (16.7%), 7 strains present resistance to 4 antibiotics ( 6.5%), another 7 strains are resistant to 5 antibiotics (6.5%), 4 strains are resistant to 6 antibiotics (3.7%), only one strain is multi-resistant to 8 antibiotics (0.9%) and one more strain is resistant to 9 antibiotics ( 0.9%). The most common combination of resistance patterns was P and CC (60 strains – 55%), the strain with resistance to 8 antibiotics (CIP, FO, TSX, VA, TE, OX, MAC and GM), the one with 7 antibiotics (P, VA, TE, E, OX, CC and CF).

Conclusions. A low percentage of MRSA carriers was isolated in the sampled population, although there were more nasal (2%) than pharyngeal (1.2%) carriers. The main antibiotics to which they present resistance are penicillin, clindamycin, and erythromycin. 77% of all the strains analyzed present resistance to at least two antibiotics.

INTRODUCTION: Staphylococcus aureus is a Gram positive bacterium that lives in symbiosis with humans, it is an opportunistic and potentially lethal pathogen of great clinical importance due to the different factors of virulence, invasiveness and resistance that it can possess. In humans, it colonizes various tissues, forming part of the normal microbiota. The widespread use of antibiotics, particularly their inappropriate and excessive use, has favored the emergence and maintenance of strains of S. aureus resistant to multiple antibiotics such as penicillin, methicillin (methicillin-resistant S. aureus; MRSA), or vancomycin. They are associated with high rates of morbidity and mortality in many regions of the world. S. aureus carriers have been found in the pharynx and have been reported with high variability in different populations from 4 to 64% in the pharynx. Some studies mention a higher rate of carriers in the pharynx than in the nose when samples are taken in parallel. Currently, the study of virulence factors is carried out through whole genome sequencing (WGS). The objective of this work was to carry out the complete genome sequencing of a MRSA strain isolated from the pharynx and to see its characteristics.

METHODS: DNA extraction was performed from a strain of S. aureus isolated from the pharynx of an apparently healthy deli meat worker. DNA was sequenced at IMR Sequencing, Canada, using Illumina MiSeq technology. The sequencing quality was analyzed with the FastQC software and the de novo assembly was performed with Geneious Prime, the generated contigs were aligned with the Bowtie2 software against the reference genome of the S. aureus NRS 384 and ATCC 1680 strains. analyzed the presence of virulence and resistance genes in the platforms of VFDB, CGE, MLST, etc.

RESULTS: A 2,879,076 bp long chromosome and a 26,428 bp plasmid were obtained. The chromosome has 2,887 genes and the plasmid 34, with 2,808 and 34 coding regions, 19 rRNA genes and 56 tRNA. The genome presents the adhesin genes: atl, ebh, clfA, clfB, eap, fnbA, fnbB and has the spa-type t008 and its MLST is 8, it also has all the ica operon genes (icaA, icaB, icaC, icaD and icaR) and the sdrC, sdrD and sdrE genes involved in biofilm formation. Regarding the presence of antibiotic resistance genes, the genome sequence annotates the genes: Aph(3')-III, mecA, blaZ, mphC, and msrA (aminoglycosides, methicillin, penicillin, macrolides, and macrolide efflux pump). In the case of toxin genes, the genome annotates: the four hemolysin genes (hla, hlb, hlc, and hld), the enterotoxins selk and selq, plus the Panton-Valentine leukocidin (lukF-PV and lukS-PV).

CONCLUSIONS: The assembly of a complete genome of S. aureus isolated from a persistent pharyngeal carrier was carried out, several genes of resistance to antibiotics were found, the sequence typifies various genes of adhesins, formation of biofilms and toxins, particularly the two subunits of Panton-Valentine leukocidin.

Dissemination of antibiotic resistance is a major concern, especially in aquatic environments. These resistant bacteria may have serious health implications, especially for endangered species, where are included six species of sea turtles. Data on the worldwide incidence of antibiotic resistance among wildlife is still very scarce, especially concerning sea turtles. The present study aims to compile the latest studies that describe the presence of AMR in sea turtles and determine how they can impact the ecosystem and human health under the concept of One Health Sea turtles play a vital role in maintaining the health of marine ecosystems. The present study presents a total of 18 works, between the years 2006 to 2021. Of the 19 papers the majority, 47.4 % (9/19) were performed in Caretta caretta, 21% (4/19) Chelonia mydas, 5.3 % (1/19) Lepidochelys olivacea, 5.3 % (1/18) Dermochelys coriacea. The remaining 4 studies were performed on several species simultaneously These animals have been proposed as sentinel species to determine pollution levels in marine environments including antibiotic resistance since they are hosts of resistant antibiotic bacteria. They have undoubtedly an important biological indicator of environmental health, particularly in the case of AMR in marine environments. Nevertheless, there are still gaps in knowledge about the dynamics and mechanisms routes of these agents. Often, wild animals such as sea turtles are not included in epidemiological surveillance disease control. In the future, further studies are needed under the One Health system to determine the role of sea turtles in the dissemination and acquisition of AMR in the marine ecosystem.

Multidrug-resistant bacteria represent one of the greatest challenges for modern medicine. The increasing resistance against glycopeptide antibiotics compromises the efficacy of vancomycin, for a long time considered as the last resort for the treatment of resistant Gram-positive bacteria.^1,2 To reestablish its activity, polycationic peptides were conjugated to vancomycin. Several derivatives that bear the poly arginine peptide moiety at four different sites of vancomycin were synthesized through site-specific conjugation.^3-5

The lead conjugate V_N-R6C showed high antimicrobial activity (up to 1000-fold increased) on 15 clinical isolates of linezolid- and vancomycin-resistant enterococci (LVRE, E. faecium) as well as on 25 clinical isolates of vancomycin resistant E. faecium and E. faecalis. The higher antimicrobial activity was also demonstrated by improved killing kinetics against selected strains of enterococci and staphylococci. Furthermore, the antimicrobial potential of the lead candidate V_N-R6C could be demonstrated in a murine in vivo systemic infection model. Blocking experiments using d‑Ala‑d‑Ala revealed a mode of action beyond the inhibition of cell-wall formation. Further, the peptide modification enables modulation of the pharmacokinetics allowing specific organ targeting.

Encapsulation of V_N-R6C in PEGylated liposomal nanocarrier systems prolonged the half-life of the drug after intravenous administration: studies in Wistar rats revealed a significantly prolonged circulation of the liposomal antibiotic. Microdilution testing proved that the liposomal encapsulation of V_N-R6C does not diminish the antimicrobial activity against staphylococci and enterococci. Highlighting its great potency, liposomal V_N-R6C exhibited a superior therapeutic efficacy when compared to the free drug in a Galleria mellonella larvae infection model.

Beyond vancomycin, the strategy could be proven effective for other glycopeptide and cell wall targeting antibiotics, indicating its potential applicability as a platform technology (referred to as ROVANCE technology).

Bacterial resistance dramatically affects the effectiveness of current antibiotics, being considered a big concern for Public Health. Also, some bacterial survival capabilities in harsh conditions and invasiveness can cause infection recrudescence and failure in its eradication, as often occurs with Helicobacter pylori, recognized as an important risk factor for the development of gastric adenocarcinoma. The search for new antibacterial agents led us to explore the activity of Eugenol (Figure 1), an essential oil component known for its polypharmacology and, in particular, broad-spectrum antimicrobial^1,2 and anti-H. pylori activity in vitro.³

In this study, we investigated three chemical modifications on Eugenol scaffold, generating three different series of derivatives: in series A, a diazo function was added in the ortho position; in B, the phenolic group was alkylated or incorporated into a carbamate or ester moiety; in C, the allylic portion was replaced by a differently substituted tail, including an epoxide ring, alcohol or chalcogen-bearing chains (Figure 1). The antibacterial susceptibility of H. pylori strains for these compounds was evaluated on the reference NCTC 11637 strain and three drug-resistant clinical isolates. Interestingly, some of the derivatives showed lower minimal inhibitory concentration (MIC) values on H. pylori NCTC 11637 (MICs ranging from 8 to 16 µg/mL) than the parent compound (Eugenol, MIC = 32 µg/mL). They also maintained their antibacterial activity on the resistant strains, exerting a bactericidal effect.

1. Kamatou, G. P.; Vermaak, I.; Viljoen, A. M. Molecules. 2012, 17, 6953-6981.
2. Marchese, A.; Barbieri, R.; Coppo, E.; Orhan, I. E.; Daglia, M.; Nabavi, S. F.; Izadi, M.; Abdollahi, M.; Nabavi, S. M.; Ajami, M. Crit. Rev. Microbiol. 2017, 43, 668-689.
3. Ali, S.M.; Khan, A. A.; Ahmed, I.; Musaddiq, M.; Ahmed, K. S.; Polasa, H.; Rao, L. V.; Habibullah, C. M.; Sechi, L. A.; Ahmed, N. Ann. Clin. Microbiol. Antimicrob. 2005, 4-20.

Klebsiella spp. is recognized as an emerging threat to public health worldwide mainly due to its increasing prevalence in healthcare-associated infections caused by multidrug-resistant strains producing extended-spectrum β-lactamases (ESBL). However, comparable data on its occurrence in surface waters and hospital wastewater are scarce. Therefore, we aimed to investigate the prevalence of ESBL-producing Klebsiella spp., in surface waters and hospital wastewater, and characterize the isolates phenotypically and genotypically. Seventy-seven samples were collected from different surface waters in the North of Portugal, of which 35 (45,5%) were positive for Klebsiella spp. However, 44 samples were collected from hospital wastewater in northern Portugal, of which 40 (90.9%) were positive for Klebsiella spp. The antimicrobial susceptibility was performed using the Kirby-Bauer disk diffusion method against 11 antibiotics. Screening for ESBL phenotypic production was performed by double-disk synergy. ESBL production was detected in 11 (31,4%) of 35 Klebsiella spp. isolated in surface waters, and in 20 (50%) of 40 Klebsiella spp., in hospital wastewater. The presence of different carbapenem genes (e.g., blaKPC) was analyzed by PCR in Klebsiella spp. isolates, as well as the presence of other resistance genes (e.g., blaCTX and blaSHV). The one with the highest prevalence, in the surface waters, was blaCTX (22,6%) however, in hospital wastewater, was blaSHV (52,5%). Nevertheless, in carbapenem genes, amplification was not verified, in surface waters, but in hospital wastewater, was verified in the blaKPC (10%). Monitoring the evolution of the ESBL situation and applying a One Health approach is essential to keep this problem under control.

Antimicrobial resistance (AMR) is a public health concern involving food-producing animals. Animals act as reservoir/source of antibiotic-resistant Escherichia coli that can spread to humans through the food chain or the environment.

This study aimed to characterize the AMR profiles of E. coli from fecal samples of three native Portuguese breeds (Barrosã, Cachena, and Minhota) since this information is non-existent.

From thirty extensive producing farms (10 per breed) in Northern Portugal, 480 collected samples (May-June 2023) were pooled, based on age group (8 calves and 8 cows per farm) and isolated on MacConkey Agar supplemented with or without antibiotics (4 µg/ml cefotaxime; 3 µg/ml colistin). A total of 102 characteristic E. coli colonies representing the 3 different breeds were selected for confirmation by MALDI-TOF MS, antimicrobial susceptibility testing (AST) for 10 antibiotics (EUCAST/CLSI guidelines), ESBL phenotype (DDST) screening and detection of blaTEM, blaSHV, and blaCTX-M genes by PCR.

From both calves and cows, 77% and 20% of the E. coli exhibited resistance to ≥1 antibiotic and multidrug resistance (MDR, resistance to ≥3 antimicrobial classes), respectively, from all breeds. Isolates were mostly resistant to gentamycin (72%), tetracycline (27%), and ampicillin (21%). ESBL activity was observed in 10% of E. coli isolates (from Cachena and Minhota breeds). Ongoing assays have already shown the presence of bla_TEM and bla_CTX-M genes for one isolate. This pioneering study revealed the concerning presence of MDR E. coli in iconic native Portuguese cattle breeds raised in production regimes where antibiotic use is theoretically low.

The urgent need for the development of new antibacterial drugs arises from the global increase of antibiotic resistance. In addressing this challenge, Streptomyces rochei CMB47, isolated from a Saharan soil of a coal mine provided an ethyl acetate extract which exhibited a minimum inhibitory concentration of <0.439 µg/mL against MRSA, resulting therefore a promising source of bioactive metabolites.

Medium formulation and optimization is essential for the success of an industrial production by fermentation, as it directly affects time and costs of the bioactive products.

A statistical medium optimization experimental design employing a response surface methodology (RSM) based on a second-order rotatable central composite design (RCCD) was employed to optimize the fermentation process, in favor of an enhanced production of the metabolites responsible of the bioactivity. Optimal conditions for starch and NaNO₃ concentrations, incubation time, and initial pH were determined, resulting in an inhibition zone diameter of 20 mm, closely matching the experimental value after model validation. Bioassay-guided fractionation of the crude extract yielded the most active fractions, afterwards subjected to high-performance liquid chromatography equipped with a photodiode array detector and coupled online with electrospray mass spectrometry (HPLC-DAD/ESI-MS). These results provided preliminary insights into the molecular structures of the metabolites.