Bloodstream infections, which result from introducing contaminated implants or prostheses to the patient’s body, are commonly caused by Staphylococcus aureus strains. The occurrence of staphylococcal-related bloodstream infection correlates with an elevated risk of sepsis, which poses a threat to a patient’s health and life. The microbiological diagnostic procedure of bloodstream infection takes from 3 days to 7 days, during which the patient receives broad-spectrum antibiotics that contribute to drug resistance. The application of the Solid-Phase Microextraction method (SPME) in sepsis diagnosis may reduce diagnostics time up to 2 hours.

Therefore, the aim of this study was to investigate the suitability of the Solid-Phase Microextraction method in the differentiation of methicillin-susceptible Staphylococcus aureus (MSSA) from methicillin-resistant (MRSA) strains based on the volatile compounds secreted by these bacteria. For this purpose, 5 MSSA and 5 MRSA strains were tested. Volatile compounds were isolated using a headspace-SPME modification and distributed and analyzed employing combined gas chromatography with mass spectrometry. Comparing the profiles of secreted volatile metabolites, we found significant differences between the compositions of MRSA and MSSA metabolomes. The results may serve as proof of the concept for further research aiming to create a new analytical method. Shortening the time of diagnosis of sepsis to 2 hours will significantly reduce the patient's risk of death.

The research was financially supported by funding SUBZ.D230.22.026 from the IT Simple system of Wroclaw Medical University.

Mammals ubiquitously interact with environmental and symbiotic microbes, and the effects of these interactions on animal physiology are currently the subject of intense interest. Symbionts of mammals are interesting from the point of view of their adaptation to their environment: the emergence of defense mechanisms against competitors - antibiotic activity, the absence of a cytotoxic effect on host cells, competition for mucosal attachment sites and food sources. Microflora and mucous membranes are in close interaction, exerting a mutual influence on the health of a mammal. In this study, samples of the nasal mucosa of pigs – Mangalica (Hungarian breed of domestic pig) were studied. The samples were taken in January 2022 from the noses of one-year-old domestic pigs that had not been seriously ill or treated with antibiotics. Cultures of microorganisms were isolated on SMS agar and Mueller-Hinton agar. The biodiversity of microorganisms, their antibiotic and antagonistic activity were studied. The resistance of the obtained cultures to the main human antibiotics was also tested. Antimicrobial activity of the isolated strains against a number of microorganisms was evaluated. The following test strains were used: a fungus (Aspergillus niger INA 00760), a yeast (Candida albicans CBS 8836), gram-positive bacteria (Bacillus subtilis ATCC 6633, Staphylococcus aureus 29213, Staphylococcus aureus ATCC 25293, Staphylococcus aureus ATCC 43300 (MRSA), Staphylococcus epidermidis ATCC 14990, Enterococcus faecalis ATCC 29212) and gram-negative bacteria (Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853). As the result, a strain SM-11 with pronounced antimicrobial properties was selected for further investigation. The active strain was found to produce bright green fluorescent pigment.

Annually, the incidence of diabetic foot ulcers (DFUs) varies between 9.1 to 26.1 million worldwide, with numbers increasing each year. About 25% of diabetic patients develop DFUs, with near 70% of those requiring lower limb amputation. DFUs often fail to progress past the inflammatory phase due to increased bacterial colonization and recurrent infection. Over the last decades, technology breakthroughs have demonstrated the impact of bioactive 3D, fiber-based scaffolding systems in the treatment of DFUs (DOI: 10.1016/j.ijpharm.2021.120423). In the present project, co-axial wet-spun microfibrous scaffolds are proposed as drug delivery platforms for infection control in DFUs-prevalent bacteria infested environments.

Microfibers with a shell made of poly(vinyl alcohol) (PVA) at 10wt.% in water and a core of polycaprolactone (PCL) at 10wt.% in dimethylformamide were engineered via wet-spinning in a 8wt.% Na2SO4 and 4wt.% NaOH coagulation bath. Ceftazidime and vancomycin minimum bactericidal concentrations (MBC) against S. aureus and P. aeruginosa were determined at 32.0µg/mL and 7.8µg/mL, respectively. Antibiotics were loaded at 2×MBC at the shell of the microfibers. PCL was used to sustain the scaffolding structure and convey mechanical resilience, while PVA was used primarily as a drug carrier, maintaining a local moist environment and absorbing exudates. The microfibers co-axial structure was confirmed via brightfield microscopy. Both polymers and antibiotics presence were verified via Fourier-transform infrared spectroscopy (FTIR) and UV-visible spectroscopy, following antibiotic release up to 24h in phosphate buffer (PBS, pH 7.4). Artificial exudates were used to attest the scaffold swelling capacity and map its degradation profile. Scaffolds could maintain >80% of their mass up to 28 days of incubation in dynamic conditions. Antimicrobial testing revealed the drug diffusion abilities of the scaffolding system, forming zones of inhibition in single and co-culture settings. Time-kill kinetics studies established this drug delivery platform as effective for infection control in non-sterile DFUs-mimicking environments within a 24h period.

Introduction

Aeromonads are ubiquitous in aquatic environments and the genus consists of 36 species. Aeromonas hydrophila and A. caviae are commonly involved in causing human infections such as gastroenteritis, severe skin and soft tissue infection and bacteremia [1]. Increasing usage of antimicrobial in humans, food fish and ornamental aquaculture can lead to antimicrobial resistance. In this study, we investigated the antimicrobial resistance patterns of A. hydrophila and A. caviae from clinical [2,3] and non-clinical sources [4,5,6] based on MICs using the dehydrated microdilution panel.

Methods

Thirty-six A. hydrophila (clinical=26, aquatic environments=10) and 70 A. caviae (clinical=40, aquatic environments=13, food fish =17) were subjected to antimicrobial susceptibility testing with 18 antimicrobial agents (Microscan NM44 plates). The plates were incubated at 35°C overnight and MIC values were determined according to CLSI [7].

Results and Discussion

Aeromonas hydrophila and A. caviae were resistant to eight antimicrobial agents (imipenem, meropenem, doripenem, trimethoprim-sulfamethoxazole, cefotaxime, ceftazidime, aztreonam and cefepime) ranging from 2.5% to 76.9%. A. hydrophila clinical strains were resistant at higher than that of water environmental strains towards imipenem (76.9% vs 70%) and meropenem (19.2% vs 10%) but in the opposite direction for doripenem (30.8% vs 50%). In contrast, A. caviae environmental strains primarily recovered from tank water of ornamental fish exhibited a higher resistance rate compared to clinical strains for imipenem (16.7% vs 10%), doripenem (16.7% vs 7.5%) and meropenem (16.7% vs 5%). Among imipenem resistant strains of both species, 83.3% (30/36) strains showed resistance with a MIC > 8 µg/mL which is two times above the CLSI breakpoint (> 4µg/mL). Overall, 2.8% of multidrug-resistant strains were observed in three A. hydrophila (urine, tissue and peritoneal fluid) and one A. caviae (stool).

Conclusion

Our findings highlight that imipenem should be used with caution when treating human Aeromonas infection, the aquatic environment and ornamental fish.

Drug repositioning, presented as a faster way to achieve a new pharmacological therapy with lower expenses, is an increasingly explored strategy when considering the investigation of new antibacterial compounds. Considering this scenario present in the field of science, this study aims to provide a state of the art on pharmacological repositioning, envisioning the antibacterial activity of non-antibiotic drugs. For this, the method of narrative literature review was adopted, which was supported by the use of the PICo strategy to formulate the study question. The investigation took place during January and February 2022 in electronic databases intended for the deposition of scientific articles, such as Medline, PubMed, VHL, MDPI. The period of publication of the works was not defined as a search criterion. The inclusion was due to scientific studies published in Portuguese, English and Spanish, excluding works that in their textual body did not answer the guiding question of this investigation. The analyzed results showed that several classes of drugs have both in vitro and in vivo antibiotic activity, such as the antihypertensive drug amlodipine, psychomodulators such as fluoxetine and thioridazine, and anti-inflammatory drugs such as ibuprofen. However, not all of them have an elucidated hypothesis of the reason for such an effect. Some of the mechanisms pointed out by the consulted authors were damage to the cell wall, modification of the permeability of porin proteins, inhibition of sliding hairpins that act with DNA polymerase. In addition to the antimicrobial response of non-antibiotic drugs, interesting results were also identified on the synergistic effect, when combined with some standard treatment in infectious combat. Therefore, in conclusion, the antibacterial potential of pharmacological redirection is promising, with an emphasis on anti-inflammatory, psychotropic and cardiovascular intervention drugs. However, it was still revealed the need to deepen investigations on the mechanisms of action of the compounds already investigated against bacterial strains, suggesting that research of phases II and III be developed, as well as investigations of other pharmacological classes little explored.

The biofilm is a major causative factor of persistent, hard-to-heal infections. Due to the biofilm’s persistence, even high-dose, systemic antibiotic therapy displays low antimicrobial efficacy. Therefore, there is an urgent need to search for novel bactericidal agents. Essential oils [EOs] are of great interest in this matter because of their broad spectrum of antimicrobial activity and non-specific mechanism of action.

This study aimed to evaluate the antimicrobial activity of vapour fractions of three commercially available essential oils: menthol mint (Mentha arvensis, L.), lavender (Lavandula angustifolia, Mill.), and eucalyptus (Eucalyptus globulus, Labill.) against Pseudomonas aeruginosa biofilm. For the research purposes, fourteen clinical multidrug-resistant strains and one reference bacterial strain from American Type Culture Collection (ATCC 15441) were used. The self-developed evaluation method was applied, based on the optimized resazurin staining protocol, to determine the biofilm survival after the exposure to volatile agents.

The results indicated that the EOs’ antibiofilm activity depends on the pseudomonal strains’ intraspecies variability. The lavender oil was active against five clinical strains, with the reduction rate ranging from 33% to 44%. The highest reduction level obtained for eucalyptus oil was 20%. The results for menthol mint oil were differentiated among tested strains and ranged from 5% to 53%.

The obtained outcomes indicate that tested volatile fractions of EOs possess the potential to be applied in the treatment of infections caused by Pseudomonas aeruginosa biofilm. Further research is required to determine if they can be used in monotherapy or as adjuvants of other antimicrobial agents.

This research was funded by the National Science Centre in Poland (Grant No. PREL.D230.22.003).

Objectives: The urinary tract infections (UTIs) are one of the most common community acquired infections, more often affecting women. The aim of this study is to investigate the etiological spectrum and antimicrobial resistance of most frequently isolated pathogens, associated with UTIs in ambulatory patients in Varna city, Bulgaria during a seven-month period (October 2020 - April 2021). Materials and methods: A total of 1600 urine sampes, collected from patients with suspected UTIs were tested. Screening for bacterial growth was done by HM&L Uroquattro instrument (ALIFAX, Italy). Species identification and antimicrobial susceptibility testing were performed by VITEK 2 Compact System (bioMerieux) and Kirby-Bauer disk diffusion method for 5-nitroxoline, fosfomycin and nitrofurantoin. Results: Escherichia coli was the most commonly isolated uropathogen regardless of the age group (48%, n=61), followed by Enterococcus faecalis (33%, n=42) and other representatives of order Enterobacterales (13.3%, n=18). The resistance rates in the group of Gram-negative isolates (n=79) in decreasing order were as follows: ampicillin, 64.5% > trimethoprim/sulphomethoxazole, 36% > ciprofloxacin, 29.1% > amoxicillin-clavulanate, 27.8% > cefuroxime, levofloxacin, 21.5% > fosfomycin, 13.1% > ceftriaxone, 12.6% > ceftazidime, 10.1% > gentamicin, nitrofurantoin, 6.5% > 5-nitroxoline, 4.9%. The resistance rates among the isolates of Enterococcus faecalis (n=42) were as follows: ciprofloxacin, 28.6% > gentamicin, 23.8% > levofloxacin, 19% > nitrofurantoin, 4.7% > amoxicillin, 2.4%. No resistance was detected to vancomycin and teicoplanin. Conclusion: High rates of resistance to ampicillin, trimethoprim/sulphomethoxazole and quinolones (60-30%) in the group of Gram negative uro-pathogens were detected, but 3^rd generation cephalosporins, nitrofurantoin and 5-nitroxolin retained very good activity. Among Enterococcus faecalis, the second most commonly isolated bacterial species, a decreased activity of quinolones was found too, but the aminopenicillins and nitrofurantoin remain highly active.

Abstract

The urinary tract infections (UTIs) are one of the most common community and hospital acquired infections. The rapid diagnosis and the adequate etiological therapy are factors with direct impact on the morbidity and mortality associated with these infections. The aim of this study was to evaluate the HB&L Uroquattro instrument (ALIFAX, Italy) and the Residual Antimicrobial Activity test (RAA) for rapid and correct diagnosis of UTIs in ambulatory patients in Varna city, Bulgaria during a seven-month period (October 2020 - April 2021). Material and methods: A total of 1620 urine samples, collected prospectively from 842 ambulatory patients with symptoms of UTIs were studied. All patients report an information about recent antimicrobial treatment. All samples were screened for bacterial growth using 4 – hour protocol and were tested for RAA by HB&L Uroquattro. Simultaneously the samples were inoculated on Blood agar, CLED, CPS, Mc Conkey agar plates. Results: A total of 343 urine samples (21.2%) were positive for bacterial growth by the rapid screening method. The standard cultural method was positive in 22 % (n=352). RAA was detected in 5.6 % (n=91). A total of 113 patients (13.4%) gave information for therapy with antimicrobial agents or substances with potential antimicrobial activity. Among the samples that demonstrated positive RAA, 69.2 % (n=63) were positive for bacterial growth and 30.7 % (n=28) were negative. RAA results were negative in 19 patients who informed about recent therapy with antimicrobial agents, while in the rest 94 patients the RAA test was positive for bacterial growth from the screening. Conclusion: A very good correlation between the results from the automated HB&L Uroquattro instrument and those from the traditional cultural method was found. The RAA positive results were detected in patients, receiving antimicrobial treatment. The RAA test result is of great value for correct interpretation of the culture test and help to avoid the reporting of false negative results.

Despite the recent advances achieved in food industries to fulfil the growing consumer demand for high quality and safe food, microbial contamination remains a serious issue. Bacteriophages (phages, viruses that only infect bacteria) have been recognized for their great effectiveness in controlling bacterial pathogens in agro-food industry. Phages exhibit important features that make them promising antibacterial candidates, such as their ubiquity, high specificity against a target host, self-replication capacity while their hosts are present, low inherent toxicity, easy and economical isolation and production, and a long shelf life. The incorporation of phages in food packaging can be an effective alternative to protect phages from environmental challenges and improve its efficacy, allowing slower and continuous release. Escherichia coli is one of the most important foodborne pathogens. The purpose of the study was to evaluate the efficiency of biopolymeric films incorporating phage phT4A for future application in packaging materials. The inactivation of E. coli was first assessed in vitro (liquid culture medium) and ex vivo (milk) with free phage phT4A. The in vitro results showed that phage phT4A was effective to inactivate E. coli with a reduction of about 6 log colony-forming unit per millilitre (CFU/mL) for all tested values of multiplicity of infection (MOI). In milk, a more complex matrix, a maximum inactivation of about 4 log CFU/mL was obtained after 8 h of incubation (MOI of 10 and 100). Phages were successfully incorporated in the pullulan films increasing its concentration in solution until it remains stable until the end of the assays. The antibacterial efficacy of pullulan films was demonstrated in vitro and artificially contaminated milk, with 5-3 log CFU/mL of inactivation during first 12 h of incubation. Overall, pullulan-based films incorporating phages constitute a simple approach to preserve the activity of phages in order to improve food safety.

Background: Orthopaedic surgeries are one of the major contributors to the overall surgical site infection (SSI) events worldwide. In India, SSI rates vary considerably depending on geographical location (1.6%- 38%); however, there is a lack of a national SSI surveillance system to identify risk factors for SSIs.
Aim: To identify the incidence and risk factors for SSIs, and antibiotic prescription and susceptibility patterns of infecting bacteria among the operated orthopaedic patients in a tertiary-care, teaching hospital (TH) in Central India.
Methods: Data for 1205 operated orthopaedic patients were collected prospectively from 2013 to 2016 in the TH. SSIs were identified and categorized based on the Centre for Disease Control and Prevention guidelines. The American Society for Anesthesiologists classification system was used to predict patients’ physiological status and operative risk. Patients were grouped and analysed based on the occurrence of SSIs. The Clinical and Laboratory Standard Institute guidelines were followed to process the samples, and antibiotic susceptibility tests were performed using Kirby Bauer’s disc diffusion method according to performance CLSI guidelines. Univariate and multivariable backward stepwise logistic regression was performed to identify risk factors for SSIs.
Results: Overall, 7.6% (91/1205) operated patients developed SSIs over three years. Out of 68 samples sent for culture and sensitivity testing, 22% were culture positive. The most common SSIs causing microorganism was Staphylococcus aureus (7%). Strains of S. aureus were resistant to penicillin (100%), erythromycin (80%), cotrimoxazole (80%), amikacin (60%) and cefoxitin (60%). The most commonly prescribed antibiotic was amikacin (36%). Male sex (OR 2.64; 95%CI 1.32-5.30), previous hospitalisation (OR 2.15; 95%CI 1.25-3.69), prescription of antibiotics during hospital stay before perioperative antibiotic prophylaxis (OR 4.19; 95%CI 2.51-7.00), postoperative length of hospital stay longer than 15 days (OR 3.30; 95%CI 1.83-5.95) and preoperative shower (OR 4.73; 95%CI 2.72-8.22) were identified as significant risk factors for orthopaedic SSIs.
Conclusion: Incidence rate of SSIs was relatively low compared to reported incidence range for India, yet higher than reported SSI incidences for orthopaedic procedures in high- and middle-income countries. Majority of the SSIs were caused by S. aureus. Preoperative shower was found to be a significant risk factor for developing SSIs, which is unforeseen so far. Identification of the incidences and risk factors for SSIs supports the measures to prevent and mitigate SSI events in hospitals.