Pseudomonas species prevalence, protein analysis, and antibiotic resistance: an evolving public health challenge

Prevention and control strategies for psychrophilic Pseudomonas fluorescens in food: A review

Psychrophilic Pseudomonas fluorescens can secrete extracellular enzymes, biofilms, and other substances even under refrigeration conditions, which have a negative impact on the quality of dairy products, aquatic products, meat products, produce, and other foods, causing food spoilage and huge economic losses. Therefore, strengthening the prevention and control of psychrophilic P. fluorescens in food is of great significance. Although some reviews have introduced information on P. fluorescens, there are few reviews that provide detailed information on the psychrophilic mechanism, detection, prevention, and control methods of psychrophilic P. fluorescens. Therefore, to comprehensively address the shortcomings of previous reviews, this review provides a detailed overview of the physiological characteristics, secreted spoilage factors, psychrophilic mechanisms, and prevention and control methods, such as bacteriophages, quorum sensing inhibitors, and nanomaterials of P. fluorescens. And future research directions for the prevention and control strategies of P. fluorescens are discussed. The future research focus will be on strengthening the detection of P. fluorescens and adopting a combination of multiple technologies to prevent and control P. fluorescens without affecting food nutrition and quality while preventing the occurrence of drug resistance. This article aims to provide references for improving the quality and safety of refrigerated food and extending its shelf life.

First report of MDR virulent Pseudomonas aeruginosa in apparently healthy Japanese quail (Coturnix japonica) in Bangladesh

Pseudomonas aeruginosa (P. aeruginosa) is a major pathogen associated conditions like septicaemia, respiratory disorders, and diarrhoea in poultry, particularly in Japanese quail (Coturnix japonica). The infection causes huge economical losses due to its high transmissibility, mortality and zoonotic potential. This study aimed to isolate, identify, detect virulence genes, and profile multidrug resistance (MDR) of P. aeruginosa from Japanese quail. Oral and rectal swabs were collected from 110 apparently healthy quail birds across various districts in Bangladesh. Bacterial isolation and identification were performed using cultural, morphological, biochemical, and polymerase chain reaction (PCR) methods. Antibiotic susceptibility was assessed using the disc diffusion method, and virulence genes were detected through PCR. Multivariable logistic regression was used to identify risk factors for P. aeruginosa infection. Both conventional and PCR methods revealed that 25 (22.73%) of the quail birds were positive for P. aeruginosa. The results showed that quail birds in Narsingdi were five times more likely to harbor Pseudomonas species (OR: 5.02; 95% CI: 1.34-18.84) compared to those in Mymensingh Sadar. Additionally, quail birds younger than eight weeks had nearly six times higher odds (OR: 5.93; 95% CI: 1.96-17.91) of carrying Pseudomonas compared to older birds. Female quail birds had almost four times higher odds (OR: 3.77; 95% CI: 1.30-10.93) of harboring Pseudomonas species than males. All 25 P. aeruginosa isolates exhibited multi drug-resistance (MDR) patterns. Virulence gene analysis revealed the consistent presence of exoA and rhlR in all isolates, while exoS, exoY, rhlI, and rhlAB showed variable distribution. The high prevalence of MDR and virulent P. aeruginosa in apparently healthy quail birds particularly in Mymensingh and Dhaka divisions, highlights the urgent need for a comprehensive 'One Health' approach to proactively address and mitigate the potential risk this organism poses to both quail and human populations.

Assessment of biofilm formation, antibiotic resistance patterns, and the prevalence of adhesion-related genes in clinical Staphylococcus aureus isolates

Background

This study aimed to evaluate the biofilm formation abilities of clinical Staphylococcus aureus strains, assess their antibiotic susceptibility patterns, and identify the prevalence of adhesion-associated genes.

Methodology

In this study, a total of 60 S. aureus strains were collected from urine, pus, wounds, blood, body fluid, and sputum in health centers affiliated with Abadan University of Medical Sciences, Iran. Strains were identified via microbiological methods and polymerase chain reaction (PCR) to target the nuc gene. Antibiotic susceptibility testing (AST) was conducted via the disc diffusion method. Methicillin-resistant S. aureus (MRSA) strains were identified by cefoxitin disc diffusion and PCR targeting the mecA gene. Biofilm formation was assessed via a microtiter plate assay, and the prevalence of adhesion-encoding genes was evaluated via PCR. The data were analyzed in Excel and SPSS via statistical methods, with P-values <0.05 considered significant.

Results

Using AST, daptomycin and linezolid were the most effective antibiotics (100 % susceptibility rate). According to the results of the cefoxitin disc test, 48.3 % (n = 29/60) of the strains were MRSA. All the MRSA strains harbored the mecA gene. In total, 32 % of the strains were biofilm producers. Moreover, 56.2 %, 28.1 %, and 15.6 % of the strains produced weak, moderate, and strong biofilms, respectively. There were no significant differences between the MRSA and MSSA strains in terms of the association of biofilm formation with antibiotic resistance except for erythromycin (P-value = 0.0087), gentamicin (P-value = 0.0009), and penicillin (P-value = 0.0009). The most prevalent biofilm-encoding genes were icaA (76.7 %), followed by icaD (70 %), clfA (65.0 %), and fnbA (53.3 %).

Conclusion

This study identified MRSA strains with biofilm-forming abilities that possess adhesion-associated genes. The most prevalent biofilm-encoding gene was icaA. To prevent further spread of these strains, regional preventive measures are needed.

Antimicrobial resistance, virulence gene profiling, and genetic diversity of multidrug-resistant Pseudomonas aeruginosa isolates in Mazandaran, Iran

BACKGROUND

Pseudomonas aeruginosa is a major cause of healthcare-associated infections (HAIs), particularly in immunocompromised patients, leading to high morbidity and mortality rates. This study aimed to investigate the antimicrobial resistance patterns, virulence gene profiles, and genetic diversity among P. aeruginosa isolates from hospitalized patients in Mazandaran, Iran.

METHODS

From September 2021 to April 2022, 82 non-duplicate P. aeruginosa isolates were collected from diverse clinical sources. Identification was confirmed using API 20 NE (bioMérieux, Marcy l'Etoile, France). Antimicrobial susceptibility testing was conducted using the Kirby-Bauer disk diffusion method according to CLSI guidelines to assess resistance to a range of antibiotics. The virulence profile (exoT, exoY, exoU, toxA, plcH, plcN, algD, aprA, lasB and exoS) of each P. aeruginosa isolate was determined by PCR. The genetic diversity among the strains was evaluated using the random amplification of polymorphic DNA (RAPD) technique. Clustering was based on a Dice similarity coefficient of ≥ 85%.

RESULTS

Of the 82 total strains, P. aeruginosa exhibited the highest and lowest resistance toward ticarcillin-clavulanate (98.78%) and colistin (0%), respectively. Moreover, 100% of the P. aeruginosa isolates were MDR. The following prevalence of virulence factor genes was observed: aprA, lasB, algD, toxA, plcH, exoY, and exoT in 100% of isolates. The plcN, exoS, and exoU were identified 98.78%, 67.07%, and 45.12%, respectively. The RAPD patterns obtained with primers 272 and 208 had respectively 2-19 and 6-17 bands. According to the Dice similarity coefficient of higher than 85%, 56 and 39 clusters were recognized.

CONCLUSION

The high rate of multidrug resistance combined with the widespread presence of virulence genes in P. aeruginosa isolates highlights the potential for increased infection severity, morbidity, and mortality in hospitalized patients. The substantial genetic diversity observed among isolates suggests that P. aeruginosa in this region may rapidly evolve, necessitating ongoing surveillance and more targeted antimicrobial strategies.

CLINICAL TRIAL NUMBER

Not applicable.

Exploring phenotypic and genotypic diversity among methicillin-resistant, vancomycin-resistant, and sensitive Staphylococcus aureus

BACKGROUND

Methicillin-Resistant Staphylococcus aureus (MRSA) is a global concern owing to the increasing prevalence of multidrug-resistant (MDR) strains. Vancomycin has been the primary treatment for MRSA; however, Vancomycin-resistant strains are being increasingly reported worldwide. Therefore, comparative studies are essential to support antimicrobial stewardship and improving clinical management. Ultimately, the findings from this study are expected to inform treatment strategies and guide public health interventions effectively.

MATERIAL AND METHODS

This study investigated the prevalence, antimicrobial resistance, and virulence characteristics of Vancomycin-sensitive S. aureus (VSSA) and Vancomycin-resistant S. aureus (VRSA) within MRSA strains. By employing a combination of phenotypic methods, such as antimicrobial susceptibility testing, and genotypic techniques, including molecular typing and identification of virulence genes, we obtained comprehensive insights into VRSA and VSSA profiles.

RESULTS

Of 250 clinical samples, 62 (24.8%) were S. aureus and 27 (43.5%) were identified as MRSA. All MRSA isolates exhibited MDR patterns. Most MRSA strains were VSSA (20/27, 74.1%), while 7 (25.9%) were VRSA. The VRSA isolates showed more antimicrobial resistance than VSSA isolates; however, the VRSA isolates had less virulence than VSSA isolates. Linezolid was the most effective treatment, with a 3.7% resistance rate. A higher percentage of biofilm-producing MRSA (96.3%) was confirmed by both phenotypic and genotypic methods. All isolates, except one VRSA, showed multi-virulence patterns (harbored more than 3 virulence genes). High diversity and low clonality (D-value = 0.99) were found in both VSSA and VRSA. Based on our correlation findings, the emergence of vancomycin resistance could modify the association between antimicrobial resistance and virulence, potentially affecting the pathogenic profile of these strains. The study also revealed complex interactions among host factors (including age and gender), sample origin, antimicrobial resistance, biofilm production, and virulence genes.

CONCLUSION

This study highlights the alarming spread of MRSA and VRSA, which show significant resistance and virulence.

Helicobacter pylori: Routes of Infection, Antimicrobial Resistance, and Alternative Therapies as a Means to Develop Infection Control

Helicobacter pylori (H. pylori) is a Gram-negative, spiral-shaped bacterium that colonizes the gastric epithelium and is associated with a range of gastrointestinal disorders, exhibiting a global prevalence of approximately 50%. Despite the availability of treatment options, H. pylori frequently reemerges and demonstrates increasing antibiotic resistance, which diminishes the efficacy of conventional therapies. Consequently, it is imperative to explore non-antibiotic treatment alternatives to mitigate the inappropriate use of antibiotics. This review examines H. pylori infection, encompassing transmission pathways, treatment modalities, antibiotic resistance, and eradication strategies. Additionally, it discusses alternative therapeutic approaches such as probiotics, anti-biofilm agents, phytotherapy, phototherapy, phage therapy, lactoferrin therapy, and vaccine development. These strategies aim to reduce antimicrobial resistance and enhance treatment outcomes for H. pylori infections. While alternative therapies can maintain low bacterial levels, they do not achieve complete eradication of H. pylori. These therapies are designed to bolster the immune response, minimize side effects, and provide gastroprotective benefits, rendering them suitable for adjunctive use alongside conventional treatments. Probiotics may serve as adjunctive therapy for H. pylori; however, their effectiveness as a monotherapy is limited. Photodynamic and phage therapies exhibit potential in targeting H. pylori infections, including those caused by drug-resistant strains, without the use of antibiotics. The development of a reliable vaccine is also critical for the eradication of H. pylori. This review identifies candidate antigens such as VacA, CagA, and HspA, along with various vaccine formulations, including vector-based and subunit vaccines. Some vaccines have demonstrated efficacy in clinical trials, while others have shown robust immune protection in preclinical studies. Nevertheless, each of the aforementioned alternative therapies requires thorough preclinical and clinical evaluation to ascertain their efficacy, side effects, cost-effectiveness, and patient compliance.

Prevalence, Distribution and Antimicrobial Susceptibility of Enterobacteriaceae and Non-Fermenting Gram-Negative Bacilli Isolated From Environmental Samples in a Veterinary Clinical Hospital in Madrid, Spain

Managing infections caused by multidrug-resistant Gram-negative bacilli is a major public health concern, particularly in hospitals where surfaces can act as reservoirs for resistant microorganisms. Identifying these bacteria in hospital environments is crucial for improving healthcare safety. This study aimed to analyse environmental samples from a veterinary hospital to identify prevalent microorganisms and detect antimicrobial resistance patterns. A total of 183 surface samples were collected from 26 areas at the Veterinary Clinical Hospital of Alfonso X el Sabio University in Madrid. The isolated strains were identified, and susceptibility profiles were determined via the disk diffusion method. Clonality analysis was performed using pulsed-field gel electrophoresis. In total, 109 strains were isolated: 76.15% from the Enterobacteriaceae family and 23.85% non-fermenting Gram-negative bacilli. The isolates included Klebsiella, Enterobacter, Escherichia and Pseudomonas species, which could include high-risk clones, given their ability to carry several antimicrobial resistance genes. The equine area had the highest number of isolates (n = 71), accounting for 65% of the total. High resistance indices were observed against at least five of the 16 antibiotics tested, indicating significant multidrug resistance. Clonality analysis suggested potential cross-transmission within the facility. This study sampled hospital surfaces but not personnel or animals, making contamination sources unclear. Without resampling, the effectiveness of cleaning protocols remains uncertain. Results suggest that hospital staff play a key role in bacterial transmission. The lack of specialised preventive measures in veterinary hospitals highlights a need for further research and improvement.

Effect of watering before slaughter and the evisceration method on the quality characteristics of fattened goose liver

The aim of this study was to investigate the effect of watering before slaughter and different evisceration methods on the quality characteristics of fattened goose liver. A total of randomly selected 60 male Greylag Landaise geese (Anser anser) were used to execute the experiment which had been force-fed during their growing period. In the slaughterhouse, randomized block design was followed and the birds were randomly divided into four experimental groups and half of the them (30 birds) were given 200 ml tap water. During the slaughter bleeding kinetics was measured and after the traditional processing steps (scalding, defeathering, waxing, water cooling, clearing of wax residues, rinsing, feet removal) 50 % of the birds (30 birds) were immediately eviscerated. The other half of the carcasses were eviscerated after 8 hours of cooling. Then pH and hemoglobin content were determined and the livers were vacuum packed and stored at -18 °C for 35 days (5 weeks). During this time color measurement and microbial analysis were taken. Results showed that pH was not influenced by neither the watering nor the evisceration methods. Hemoglobin content was significantly reduced by watering (P<0.001). Cold evisceration was proved to have siginificant effect on the color parameters (P<0.001), however the impact was not immediate, the difference was first detected on day 21. According to microbiological analysis four species were identified but none of them are known to produce hydrogen sulfide (H2S) which is required to the formation of sulfhemoglobin which compound is most likely responsible for the greenish discoloration occured during the storage. In summary, it can be stated that the evisceration method had a great impact on the color of fattened goose livers and undesirable changes - e.g. surface greening - which commonly occur in case of vacuum packed and frozen stored livers could be prevented by the application of warm evisceration.

Prevalence and molecular characterization of ESBL-producing Escherichia coli isolated from broiler chicken and their respective farms environment in Malaysia

BACKGROUND

Extended spectrum beta-lactamase-producing Escherichia coli (ESBL-EC) is an increasing public health threat. This study aimed to determine the prevalence and characterization of ESBL-producing Escherichia coli (E. coli) isolated from broiler chicken and their farm environment, in Kelantan Malaysia.

METHODS

Escherichia coli was isolated from 453 collected samples, including 210 cloacal swabs and 243 environmental samples. The antimicrobial susceptibility profile of the E. coli isolates was assessed for sixteen antibiotics using the disc diffusion method. The E. coli isolates were evaluated for phenotypic ESBL production using modified double disc synergy. After extraction of genomic DNA, ESBL resistance genes, phylogenetic group, and virulence genes were detected by PCR using appropriate primers. ESBL genes were further confirmed by sequencing. The molecular typing of E. coli strains was determined by Multilocus Sequence Typing (MLST).

RESULTS

A total of 93.8% (425/453) E. coli were isolated from the collected samples. Out of 334 E. coli isolates screened, 14.7% (49/334) were phenotypically ESBL producers. All the ESBL-EC were resistant to tetracycline, ciprofloxacin, and ampicillin. Thus, 100% of the ESBL-EC were multidrug resistant. Of the ESBL-EC 81.6% were positive for at least one ESBL encoding gene. The most prevalent ESBL gene detected was blaTEM (77.6%; 38/49) followed by blaCTX-M (32.7%; 16/49) and blaSHV (18.4%; 9/49). The majority of ESBL-EC belonged to phylogenic groups A followed by B1 accounting for 44.9% and 12.2%, respectively. The most frequently identified sequence types were ST10 (n = 3) and ST206 (n = 3). The most detected virulence genes in the E. coli isolates were astA (33.3%; 22/66) followed by iss (15.2%; 10/66).

CONCLUSIONS

Our results show both broiler chicken and their respective farms environment were reservoirs of multi-drug resistant ESBL-producing E. coli and ESBL resistance genes.

Research progress in the use of lactic acid bacteria as natural biopreservatives against Pseudomonas spp. in meat and meat products: A review

Meat and meat products represent excellent sources of key nutrients for human health, such as protein, essential amino acids, B vitamins, and minerals. However, they are recognized as highly perishable foods since they represent an ideal substrate for the growth of spoilage and pathogenic microorganisms. Meat spoilage is a complex process that involves multiple microorganisms and a combination of intrinsic and extrinsic ecological factors. One of the most common causative agents of meat spoilage is represented by species of the genus Pseudomonas. To prevent the development of such undesired microorganisms, chemical preservatives are usually exploited by the meat industry. However, the growing consumers' concerns about potential health issues linked to the consumption of chemical preservatives has prompted the food industry to develop alternative strategies to prevent microbial spoilage in meat and meat products. Besides to the application of physical strategies, the interest towards the use of natural preservatives, such as bioprotective microorganisms (e.g., lactic acid bacteria) and their metabolites, has rapidly grown. When used in meat and meat-based products, lactic acid bacteria exhibited a bioprotective activity against spoilage and even foodborne pathogens, thanks to the production of different inhibitory compounds including organic acids, bacteriocins, carbon dioxide, hydrogen peroxide, ethanol, N-diacetyl, and lactones. This bioprotective activity might justify the use of lactic acid bacteria or their metabolites as natural preservatives to extend the shelf-life of the products. However, the effectiveness of antimicrobial activity against Pseudomonas in meat and meat products still needs to be investigated to understand the influence of the type of end product, the type of packaging, and the storage conditions (time and temperature). Moreover, the antimicrobial activity of lactic acid bacteria must also be evaluated taking into consideration their ability to maintain the sensory features of fresh meat (whether whole or minced), without negatively affecting its sourness and acidity. Of note, the results herein discussed emphasize the challenges occurred in translating in vitro findings into practical applications due to the complex interactions between bacteria, antimicrobial compounds, and food matrices.

Spice-Induced Metal Contamination and Microbiological Risk Assessment of Instant Noodles Prepared for Human Consumption

With the rising worries of potential metal contamination in cooked noodles, this study aimed at unravelling, for the first time, the possible source of metal contamination in cooked noodles. Noodles cooked with full spices (CWFS), cooked with half spices (CWHS), cooked with quarter spices (CWQS), and cooked with no spices (CWNS: control) and their spices were analysed for metals using inductively coupled plasma-atomic emission spectrometry. The microbiological quality of the noodles was also evaluated. Metal concentrations in cooked noodles varied with spice quantity. Noodles CWFS had the highest significant (p < 0.05) concentration of Pb (0.36 ± 0.12 mg/kg), Ni (1.05 ± 0.01 mg/kg), Cd (0.07 ± 0.04 mg/kg), Co (0.02 ± 0.002 mg/kg), and Na (9.45 ± 0.04 mg/kg), compared to the control (CWNS). The mean Pb and Ni of spice and cooked noodles were above the WHO acceptable limits for food and could be harmful to consumers. Pearson's correlation and PCA showed that packed noodle spices introduced metals into the cooked noodles. Although the hazard indices (adults and children) in all noodle's groups were less than 1, children still had the potential to contract cancer from Ni exposure because the carcinogenic risk values of CWQS (2.87 × 10-4), CWHS (3.03 × 10-4), and CWFS (3.21 × 10-4) were greater than 10-4. Microbiological analysis revealed the presence of potential pathogens that showed multidrug resistance and the ability to elaborate protease and amylase enzymes. Given the impending chronic health risks inherent in processed noodles, consistent consumption should be avoided.

Multidrug-Resistant Proteus mirabilis and Other Gram-Negative Species Isolated from Native Egyptian Chicken Carcasses

Poultry carcasses may be reservoirs for the zoonotic transmission of antimicrobial-resistant bacteria to humans and pose a major public health hazard. During the isolation of Salmonella from poultry and other foods, many of the presumptive typical Salmonella colonies on xylose lysine deoxycholate (XLD) agar were found to lack the invA gene, which is the specific target gene for Salmonella spp. Therefore, the current study aimed to estimate the prevalence and antimicrobial resistance profiles of extensively drug-resistant invA-negative non-Salmonella isolates recovered from native Egyptian chicken carcasses as presumptive Salmonella colonies on XLD agar. The non-Salmonella isolates were detected in 84% (126/150) of the examined native Egyptian chicken carcasses and classified into five genera, with prevalence rates of 64% (96/150), 14% (21/150), 6.7% (10/150), 3.3% (5/150), and 1.3% (2/150) for Proteus, Citrobacter, Shigella, Pseudomonas, and Edwardsiella, respectively. One hundred and ninety-five invA-negative, non-verified presumptive Salmonella isolates were recovered and classified at the species level into Proteus mirabilis (132/195; 67.7%), Proteus vulgaris (11/195; 5.6%), Citrobacter freundii (26/195; 13.3%), Shigella flexneri (8/195; 4.1%), Shigella sonnei (6/195; 3.1%), Shigella dysenteriae (3/195; 1.5%), Pseudomonas fluorescens (6/195; 3.1%), and Edwardsiella tarda (3/195; 1.5%). All (195/195; 100%) of these isolates showed resistance against cefaclor and fosfomycin. Additionally, these isolates showed high resistance rates of 98%, 92.8%, 89.7%, 89.2%, 89.2%, 86.7%, 80%, 78.5%, 74.4%, and 73.9% against cephalothin, azithromycin, vancomycin, nalidixic acid, tetracycline, sulfamethoxazole/trimethoprim, cefepime, gentamicin, cefotaxime, and ciprofloxacin, respectively. Interestingly, all (195/195; 100%) of the identified isolates were resistant to at least five antibiotics and exhibited an average MAR (multiple antibiotic resistance) index of 0.783. Furthermore, 73.9% of the examined isolates were classified as extensively drug-resistant, with an MAR index equal to 0.830. The high prevalence of extensively drug-resistant foodborne Proteus, Citrobacter, Shigella, Pseudomonas, and Edwardsiella isolated from native chicken carcasses poses a great hazard to public health and necessitates more monitoring and concern about the overuse and misuse of antibiotics in humans and animals. This study also recommends the strict implementation of GHP (good hygienic practices) and GMP (good manufacturing practices) in the chicken meat supply chain to protect consumer health.

Assessment of the presence of multidrug-resistant Escherichia coli, Salmonella and Staphylococcus in chicken meat, eggs and faeces in Mymensingh division of Bangladesh

The emergence of bacteria that is resistant to several drugs of clinical importance poses a threat to successful treatment, a phenomenon known as multidrug resistance that affects diverse classes of antibiotics. The purpose of this study was to evaluate the prevalence of multidrug-resistant Escherichia coli, Salmonella spp. and Staphylococcus aureus in chicken egg, meat and faeces from four districts of Bangladesh. A total of 120 chicken samples were collected from different poultry farms. Conventional culture and molecular detection methods were used for identification of bacterial isolates from the collected samples followed by antibiotic susceptibility test through the disc diffusion method, finally antibiotic resistant genes were detected by PCR. E. coli, Salmonella spp. and Staphylococcus aureus were detected in meat, egg and faecal samples. Antimicrobial susceptibility results revealed isolates from faeces were 100 % resistant to amoxicillin, while all S. aureus and Salmonella sp. from faeces were resistant to doxycycline, tetracycline and erythromycin. Salmonella spp. isolates from eggs indicated 100 % resistance to erythromycin, amoxycillin, while E. coli were 100 % resistant to erythromycin. E. coli and S. aureus from meat were 100 % resistant to amoxicillin and erythromycin. However, Salmonella spp. from eggs were 100 % susceptible to doxycycline, gentamicin, levofloxacin and tetracycline. The mecA and aac(3)-IV genes were only found in S. aureus and E. coli, respectively. The Sul1, tetB, and aadA1 were highest in Salmonella spp. and S. aureus, while the sul1, tetA and bla SHV were higher in E. coli. Isolates from all samples were multidrug resistant. These findings indicate a high risk of transmission of resistance genes from microbial contamination to food of animal origin. The study emphasizes the need for effective biosecurity measures, responsible antibiotic use, and strict regulations in poultry production to prevent the spread of antibiotic resistance.

Psychrotrophic Bacteria Threatening the Safety of Animal-Derived Foods: Characteristics, Contamination, and Control Strategies

Animal-derived foods, such as meat and dairy products, are prone to spoilage by psychrotrophic bacteria due to their high-water activity and nutritional value. These bacteria can grow at refrigerated temperatures, posing significant concerns for food safety and quality. Psychrotrophic bacteria, including Pseudomonas, Listeria, and Yersinia, not only spoil food but can also produce heat-resistant enzymes and toxins, posing health risks. This review examines the characteristics and species composition of psychrotrophic bacteria in animal-derived foods, their impact on food spoilage and safety, and contamination patterns in various products. It explores several nonthermal techniques to combat bacterial contamination as alternatives to conventional thermal methods, which can affect food quality. This review highlights the importance of developing nonthermal technologies to control psychrotrophic bacteria that threaten the cold storage of animal-derived foods. By adopting these technologies, the food industry can better ensure the safety and quality of animal-derived foods for consumers.

The Occurrence of Colistin Resistance in Potential Lactic Acid Bacteria of Food-Producing Animals in India

The overuse of colistin, the last-resort antibiotic, has led to the emergence of colistin-resistant bacteria, which is a major concern. Lactic acid bacteria which are generally regarded as safe are known to be reservoirs of antibiotic resistance that possibly pose a threat to human and animal health. Therefore, this study assessed the prevalence of colistin antimicrobial resistance in livestock in India, that is lactic acid bacteria in healthy chickens, sheep, beef, and swine of Mysore. Diverse phenotypic and genotypic colistin resistance were examined among the lactic acid bacterial species (n = 84) isolated from chicken (n = 44), sheep (n = 16), beef (n = 14), and swine (n = 10). Hi-comb, double-disk diffusion tests, Minimum Inhibitory Concentration (MIC), and biofilm formation were assessed for phenotypic colistin resistance. Specific primers for colistin-resistant genes were used for the determination of genotypic colistin resistance. Around 20%, 18%, and 1% were colistin-resistant Lactobacillus, Enterococcus, and Pediococcus species, respectively. Among these, 66.67% exhibited MDR phenotypes, including colistin antibiotic. The identified resistant isolates are Levilactobacillus brevis LBA and LBB (2), Limosilactobacillus fermentum LBF (1), and Pediococcus acidilactici CHBI (1). The mcr-1 and mcr-3 genes were detected in Levilactobacillus brevis LBA, LBB, and Pediococcus acidilactici CHBI isolated from chicken and sheep intestines respectively. The study identified colistin resistance determinants in lactobacilli from food animals, emphasizing the need for enhanced surveillance and monitoring of resistance spread. These findings underscore colistin resistance as a significant medical concern and should be integrated into India's ongoing antimicrobial resistance monitoring programs.

Prevalence, antimicrobial susceptibility profiles and resistant gene identification of bovine subclinical mastitis pathogens in Bangladesh

Subclinical mastitis (SCM), a silent threat in the dairy sector of Bangladesh poses a significant economic impact and serves as a potential source of infection for healthy cows, hindering efforts to achieve milk self-sufficiency. Despite the importance of this issue, limited research has been conducted on mastitis in Sylhet region of Bangladesh. This study aimed to investigate the molecular prevalence, antimicrobial susceptibility profile and resistant genes detection on pathogens (Staphylococcus aureus, Escherichia coli, and Klebsiella pneumoniae) causing SCM. In a cross-sectional study utilizing convenience sampling, 325 milk samples were collected from apparently healthy dairy cows. Initially, SCM was detected using the modified Whiteside test (MWST) method. Suspected positive samples were then subjected to bacteriological culture and standard biochemical assays, followed by molecular identification through polymerase chain reaction (PCR). Finally, antimicrobial susceptibility testing was conducted on all PCR-positive samples using the Kirby-Bauer disk diffusion method on Mueller-Hinton agar. In the Sylhet district, the prevalence of SCM was 64.92 % (211 out of 325) at the individual animal level and 82.69 % (43 out of 52) at the herd level. Among the SCM-positive animals, S . aureus was found in 31.75 % (67 out of 211) of cases, E . coli in 81.99 % (173 out of 211), and K . pneumoniae in 66.82 % (141 out of 211). K . pneumoniae had the highest prevalence at 60 % in Zakiganj, S . aureus at 45 % in Zakiganj, and E . coli at 72 % in Bishwanath Upazila. Extended spectrum beta lactamase (ESBL) genes bla TEM , bla OXA, bla CTX-M1, bla CTX-M2, MultiCase DHA were identified. Additionally, antibiotic resistance genes tet(A), AAC (3)-iv, and Sul1 were also detected. The pathogens exhibited resistance to Penicillins (ampicillin, amoxicillin), Cephems (cefuroxime, ceftazidime), and Tetracyclines (tetracycline). However, all three bacteria were highly sensitive to meropenem, amikacin, gentamicin, ciprofloxacin, and sulfamethoxazole-trimethoprim. These findings highlight the critical need for targeted antimicrobial stewardship and effective control measures to mitigate the impact of SCM on dairy production and animal health in the Sylhet region of Bangladesh.

A unique combination of natural fatty acids from Hermetia illucens fly larvae fat effectively combats virulence factors and biofilms of MDR hypervirulent mucoviscus Klebsiella pneumoniae strains by increasing Lewis acid-base/van der Waals interactions in bacterial wall membranes

Introduction

Hypervirulent Klebsiella pneumoniae (hvKp) and carbapenem-resistant K. pneumoniae (CR-Kp) are rapidly emerging as opportunistic pathogens that have a global impact leading to a significant increase in mortality rates among clinical patients. Anti-virulence strategies that target bacterial behavior, such as adhesion and biofilm formation, have been proposed as alternatives to biocidal antibiotic treatments to reduce the rapid emergence of bacterial resistance. The main objective of this study was to examine the efficacy of fatty acid-enriched extract (AWME3) derived from the fat of Black Soldier Fly larvae (Hermetia illucens) in fighting against biofilms of multi-drug resistant (MDR) and highly virulent Klebsiella pneumoniae (hvKp) pathogens. Additionally, the study also aimed to investigate the potential mechanisms underlying this effect.

Methods

Crystal violet (CV) and ethidium bromide (EtBr) assays show how AWME3 affects the formation of mixed and mature biofilms by the KP ATCC BAA-2473, KPi1627, and KPM9 strains. AWME3 has shown exceptional efficacy in combating the hypermucoviscosity (HMV) virulent factors of KPi1627 and KPM9 strains when tested using the string assay. The rudimentary motility of MDR KPM9 and KP ATCC BAA-2473 strains was detected through swimming, swarming, and twitching assays. The cell wall membrane disturbances induced by AWME3 were detected by light and scanning electron microscopy and further validated by an increase in the bacterial cell wall permeability and Lewis acid-base/van der Waals characteristics of K. pneumoniae strains tested by MATS (microbial adhesion to solvents) method.

Results

After being exposed to 0.5 MIC (0.125 mg/ml) of AWME3, a significant reduction in the rudimentary motility of MDR KPM9 and KP ATCC BAA-2473 strains, whereas the treated bacterial strains exhibited motility between 4.23 ± 0.25 and 4.47 ± 0.25 mm, while the non-treated control groups showed significantly higher motility ranging from 8.5 ± 0.5 to 10.5 ± 0.5 mm.

Conclusion

In conclusion, this study demonstrates the exceptional capability of the natural AWME3 extract enriched with a unique combination of fatty acids to effectively eliminate the biofilms formed by the highly drug-resistant and highly virulent K. pneumoniae (hvKp) pathogens. Our results highlight the opportunity to control and minimize the rapid emergence of bacterial resistance through the treatment using AWME3 of biofilm-associated infections caused by hvKp and CRKp pathogens.

Extensively and multidrug-resistant bacterial strains: case studies of antibiotics resistance

The development of antibiotic resistance compromises the effectiveness of our most effective defenses against bacterial infections, presenting a threat to global health. To date, a large number of research articles exist in the literature describing the case reports associated with extensively drug-resistant (XDR) and multidrug-resistant (MDR) bacterial strains. However, these findings are scattered, making it time-consuming for researchers to locate promising results and there remains a need for a comparative study to compile these case reports from various geographical regions including the Kingdom of Saudi Arabia. Additionally, no study has yet been published that compares the genetic variations and case reports of MDR and XDR strains identified from Saudi Arabia, the Middle East, Central Europe, and Asian countries. This study attempts to provide a comparative analysis of several MDR and XDR case reports from Saudi Arabia alongside other countries. Furthermore, the purpose of this work is to demonstrate the genetic variations in the genes underlying the resistance mechanisms seen in MDR and XDR bacterial strains that have been reported in Saudi Arabia and other countries. To cover the gap, this comprehensive review explores the complex trends in antibiotic resistance and the growing risk posed by superbugs. We provide context on the concerning spread of drug-resistant bacteria by analyzing the fundamental mechanisms of antibiotic resistance and looking into individual case reports. In this article, we compiled various cases and stories associated with XDR and MDR strains from Saudi Arabia and various other countries including China, Egypt, India, Poland, Pakistan, and Taiwan. This review will serve as basis for highlighting the growing threat of MDR, XDR bacterial strains in Saudi Arabia, and poses the urgent need for national action plans, stewardship programs, preventive measures, and novel antibiotics research in the Kingdom.

Complete genome sequence, phenotypic correlation and pangenome analysis of uropathogenic Klebsiella spp

Urinary tract infections (UTI) by antibiotic resistant and virulent K. pneumoniae are a growing concern. Understanding the genome and validating the genomic profile along with pangenome analysis will facilitate surveillance of high-risk clones of K. pneumoniae to underpin management strategies toward early detection. The present study aims to correlate resistome with phenotypic antimicrobial resistance and virulome with pathogenicity in Klebsiella spp. The present study aimed to perform complete genome sequences of Klebsiella spp. and to analyse the correlation of resistome with phenotypic antimicrobial resistance and virulome with pathogenicity. To understand the resistome, pangenome and virulome in the Klebsiella spp, the ResFinder, CARD, IS Finder, PlasmidFinder, PHASTER, Roary, VFDB were used. The phenotypic susceptibility profiling identified the uropathogenic kp3 to exhibit multi drug resistance. The resistome and in vitro antimicrobial profiling showed concordance with all the tested antibiotics against the study strains. Hypermucoviscosity was not observed for any of the test isolates; this phenotypic character matches perfectly with the absence of rmpA and magA genes. To the best of our knowledge, this is the first report on the presence of ste, stf, stc and sti major fimbrial operons of Salmonella enterica serotype Typhimurium in K. pneumoniae genome. The study identifies the discordance of virulome and virulence in Klebsiella spp. The complete genome analysis and phenotypic correlation identify uropathogenic K. pneumoniae kp3 as a carbapenem-resistant and virulent pathogen. The Pangenome of K. pneumoniae was open suggesting high genetic diversity. Diverse K serotypes were observed. Sequence typing reveals the prevalence of K. pneumoniae high-risk clones in UTI catheterised patients. The study also highlights the concordance of resistome and in vitro susceptibility tests. Importantly, the study identifies the necessity of virulome and phenotypic virulence markers for timely diagnosis and immediate treatment for the management of high-risk K. pneumoniae clones.

Colistin-, cefepime-, and levofloxacin-resistant Salmonella enterica serovars isolated from Egyptian chicken carcasses

OBJECTIVES

The emergence of multidrug-resistant (MDR) Salmonella strains, especially resistant ones toward critically important antimicrobial classes such as fluoroquinolones and third- and fourth-generation cephalosporins, is a growing public health concern. The current study, therefore, aimed to determine the prevalence, and existence of virulence genes (invA, stn, and spvC genes), antimicrobial resistance profiles, and the presence of β-lactamase resistance genes (blaOXA, blaCTX-M1, blaSHV, and blaTEM) in Salmonella strains isolated from native chicken carcasses in Egypt marketed in Mansoura, Egypt, as well as spotlight the risk of isolated MDR, colistin-, cefepime-, and levofloxacin-resistant Salmonella enterica serovars to public health.

METHODS

One hundred fifty freshly dressed native chicken carcasses were collected from different poultry shops in Mansoura City, Egypt between July 2022 and November 2022. Salmonella isolation was performed using standard bacteriological techniques, including pre-enrichment in buffered peptone water (BPW), selective enrichment in Rappaport Vassiliadis broth (RVS), and cultivating on the surface of xylose-lysine-desoxycholate (XLD) agar. All suspected Salmonella colonies were subjected to biochemical tests, serological identification using slide agglutination test, and Polymerase Chain Reaction (PCR) targeting the invasion A gene (invA; Salmonella marker gene). Afterward, all molecularly verified isolates were screened for the presence of virulence genes (stn and spvC). The antimicrobial susceptibility testing for isolated Salmonella strains towards the 16 antimicrobial agents tested was analyzed by Kirby-Bauer disc diffusion method, except for colistin, in which the minimum inhibition concentration (MIC) was determined by broth microdilution technique. Furthermore, 82 cefotaxime-resistant Salmonella isolates were tested using multiplex PCR targeting the β-lactamase resistance genes, including blaOXA, blaCTX-M1, blaSHV, and blaTEM genes.

RESULTS

Salmonella enterica species were molecularly confirmed via the invA Salmonella marker gene in 18% (27/150) of the freshly dressed native chicken carcasses. Twelve Salmonella serotypes were identified among 129 confirmed Salmonella isolates with the most predominant serotypes were S. Kentucky, S. Enteritidis, S. Typhimurium, and S. Molade with an incidence of 19.4% (25/129), 17.1% (22/129), 17.1% (22/129), and 10.9% (14/129), respectively. All the identified Salmonella isolates (n = 129) were positive for both invA and stn genes, while only 31.8% (41/129) of isolates were positive for the spvC gene. One hundred twenty-one (93.8%) of the 129 Salmonella-verified isolates were resistant to at least three antibiotics. Interestingly, 3.9%, 14.7%, and 75.2% of isolates were categorized into pan-drug-resistant, extensively drug-resistant, and multidrug-resistant, respectively. The average MAR index for the 129 isolates tested was 0.505. Exactly, 82.2%, 82.2%, 63.6%, 51.9%, 50.4%, 48.8%, 11.6%, and 10.1% of isolated Salmonella strains were resistant to cefepime, colistin, cefotaxime, ceftazidime/clavulanic acid, levofloxacin, ciprofloxacin, azithromycin, and meropenem, respectively. Thirty-one out (37.8%) of the 82 cefotaxime-resistant Salmonella isolates were β-lactamase producers with the blaTEM as the most predominant β-lactamase resistance gene, followed by blaCTX-M1 and blaOXA genes, which were detected in 21, 16, and 14 isolates respectively).

CONCLUSION

The high prevalence of MDR-, colistin-, cefepime-, and levofloxacin-resistant Salmonella serovars among Salmonella isolates from native chicken is alarming as these antimicrobials are critically important in treating severe salmonellosis cases and boost the urgent need for controlling antibiotic usage in veterinary and human medicine to protect public health.

High frequency of multidrug-resistant Escherichia coli from cattle in the Cerrado and Pantanal biomes of Brazil

The indiscriminate use of antimicrobials has led to the emergence of resistant bacteria, especially pathogenic strains of Escherichia coli, which are associated with diseases in animals and humans. The aim of the present study was to characterize E. coli isolates in calves with regards to the presence of virulence genes and investigate the resistance of the isolates to different antimicrobials. Between 2021 and 2023, 456 fecal samples were collected from calves in the Pantanal and Cerrado biomes of the state of Mato Grosso do Sul, Brazil. All samples were subjected to microbiological analysis and disc diffusion antibiogram testing. The polymerase chain reaction method was used to detect virulence genes. Bacterial growth was found in 451 of the 456 samples and biochemically identified as Escherichia coli. All 451 isolates (100 %) exhibited some phenotypic resistance to antimicrobials and 67.62 % exhibited multidrug resistance. The frequency of multidrug-resistant isolates in the Cerrado biome was significantly higher than that in the Pantanal biome (p = 0.0001). In the Cerrado, the most common pathotype was Shiga toxin-producing Escherichia coli (STEC) (28 %), followed by toxigenic Escherichia coli (ETEC) (11 %), enterohemorrhagic Escherichia coli (EHEC) (8 %) and enteropathogenic Escherichia coli (EPEC) (2 %). In most cases, the concomitant occurrence of pathotypes was more common, the most frequent of which were ETEC + STEC (33 %), ETEC + EHEC (15 %) and ETEC + EPEC (3 %). The STEC pathotype (30 %) was also found more frequently in the Pantanal, followed by EHEC (12 %), ETEC (9 %) and EPEC (6 %). The STEC pathotype had a significantly higher frequency of multidrug resistance (p = 0.0486) compared to the other pathotypes identified. The frequency of resistance was lower in strains from the Pantanal biome compared to those from the Cerrado biome. Although some factors are discussed in this paper, it is necessary to clarify the reasons for this difference and the possible impacts of these findings on both animal and human health in the region.

Meta-analysis of antimicrobial activity of Allium, Ocimum, and Thymus spp. confirms their promising application for increasing food safety

Biopreservation strategies such as the use of Mediterranean plant extracts to ensure food safety are promising to deal with the emergence of antimicrobial resistances and the overreliance on food chemical additives. In the last few decades, antimicrobial susceptibility testing (AST) for evaluating the in vitro antibacterial potential of plant extracts against the most relevant foodborne pathogens has been widely reported in the literature. The current meta-analysis aimed to summarise and analyse the extensive evidence available in the literature regarding the in vitro antimicrobial capability of Allium, Ocimum and Thymus spp. extracts against foodborne pathogens. A systematic review was carried out to gather data on AST results of these extracts against Listeria monocytogenes, Staphylococcus aureus, Salmonella spp., Escherichia coli and Bacillus cereus, including inhibition diameters (ID) and minimum inhibitory concentrations (MIC). A total of 742 records were gathered from a raw collection of 2,065 articles. Weighted mixed-effect linear models were adjusted to data to obtain pooled ID, pooled MIC and the relationship between both model estimations and observations. The pooled results revealed B. cereus as the most susceptible bacteria to Allium sativum (pooled ID = 20.64 ± 0.61 mm) by diffusion methods and S. aureus (pooled MIC = 0.146 mg/mL) by dilution methods. Diffusion methods did not yield conclusive results for Ocimum spp. extracts; however, the lowest pooled MIC was obtained for S. aureus (0.263 mg/mL). Among the foodborne pathogens evaluated, B. cereus showed the highest sensitivity to Thymus spp. extracts by both diffusion and dilution methods (pooled ID = 28.90 ± 2.34 mm and MIC = 0.075 mg/mL). The methodology used for plant extraction was found to not significantly affect MIC values (p > 0.05). Overall, the antimicrobial effectiveness of the studied extracts against Gram-positive and Gram-negative bacteria was demonstrated. Finally, the robustness of the meta-regression model was confirmed, also revealing an inversely proportional correlation between the ID and MIC measurements (p < 0.0001). These results provide a robust scientific basis on the factors affecting the in vitro antimicrobial efficacy of extracts from Mediterranean plants. They also provide valuable information for stakeholders involved in their industrial application in food, including producers, regulatory agencies and consumers which demand green-labelled foods.

High prevalence of multidrug-resistant Pseudomonas aeruginosa carrying integron and exoA, exoS, and exoU genes isolated from burn patients in Ahvaz, southwest Iran: A retrospective study

Background

Pseudomonas aeruginosa as an opportunistic pathogen produces several virulence factors. This study evaluated the relative frequency of exoenzymes (exo) A, U and S genes and integron classes (I, II, and III) among multi-drug-resistant clinical P. aeruginosa isolates from burn patients in Ahvaz, southwest of Iran.

Methods

In this cross-sectional study P. aeruginosa isolates were recovered from 355 wound samples. The antimicrobial susceptibility test was done by disk agar diffusion method on Muller-Hinton agar according to the Clinical and Laboratory Standards Institute. MDR isolates were defined if they showed simultaneous resistance to 3 antibiotics. Extensively drug-resistant was defined as nonsusceptibility to at least one agent in all but two or fewer antimicrobial categories. The presence of class I, II, and III integrons and virulence genes was determined using a PCR assay on extracted DNA.

Results

Overall, 145 clinical P. aeruginosa isolates were confirmed with biochemical and PCR tests. Overall, 35% (52/145) of the isolates were taken from males and 64% (93/145) from female hospitalized burn patients. The highest resistance rates of P. aeruginosa isolates to antibiotics were related to piperacillin 59% (n = 86/145) and piperacillin-tazobactam 57% (n = 83/145). A total of 100% of isolates were resistant to at least one antibiotic. MDR and XDR P. aeruginosa had a frequency of 60% and 29%, respectively. The prevalence of integron classes I, II, and III in P. aeruginosa was 60%, 7.58%, and 3.44%, respectively. IntI was more common in MDR and XDR P. aeruginosa isolates. In addition, 70(48%) of P. aeruginosa isolates did not harbor integron genes. Besides, exoA, exoS, and exoU in P. aeruginosa had a frequency of 55%, 55%, and 56%, respectively.

Conclusion

It was found that P. aeruginosa as a potent pathogen with strong virulence factors and high antibiotic resistance in the health community can cause refractory diseases in burn patients.

Unveiling the genetic architecture and transmission dynamics of a novel multidrug-resistant plasmid harboring blaNDM-5 in E. Coli ST167: implications for antibiotic resistance management

BACKGROUND

The emergence of multidrug-resistant (MDR) Escherichia coli strains poses significant challenges in clinical settings, particularly when these strains harbor New Delhi metallo-ß-lactamase (NDM) gene, which confer resistance to carbapenems, a critical class of last-resort antibiotics. This study investigates the genetic characteristics and implications of a novel blaNDM-5-carrying plasmid pNDM-5-0083 isolated from an E. coli strain GZ04-0083 from clinical specimen in Zhongshan, China.

RESULTS

Phenotypic and genotypic evaluations confirmed that the E. coli ST167 strain GZ04-0083 is a multidrug-resistant organism, showing resistance to diverse classes of antibiotics including ß-lactams, carbapenems, fluoroquinolones, aminoglycosides, and sulfonamides, while maintaining susceptibility to monobactams. Investigations involving S1 pulsed-field gel electrophoresis, Southern blot analysis, and conjugation experiments, alongside genomic sequencing, confirmed the presence of the blaNDM-5 gene within a 146-kb IncFIB plasmid pNDM-5-0083. This evidence underscores a significant risk for the horizontal transfer of resistance genes among bacterial populations. Detailed annotations of genetic elements-such as resistance genes, transposons, and insertion sequences-and comparative BLAST analyses with other blaNDM-5-carrying plasmids, revealed a unique architectural configuration in the pNDM-5-0083. The MDR region of this plasmid shares a conserved gene arrangement (repA-IS15DIV-blaNDM-5-bleMBL-IS91-suI2-aadA2-dfrA12) with three previously reported plasmids, indicating a potential for dynamic genetic recombination and evolution within the MDR region. Additionally, the integration of virulence factors, including the iro and sit gene clusters and enolase, into its genetic architecture poses further therapeutic challenges by enhancing the strain's pathogenicity through improved host tissue colonization, immune evasion, and increased infection severity.

CONCLUSIONS

The detailed identification and characterization of pNDM-5-0083 enhance our understanding of the mechanisms facilitating the spread of carbapenem resistance. This study illuminates the intricate interplay among various genetic elements within the novel blaNDM-5-carrying plasmid, which are crucial for the stability and mobility of resistance genes across bacterial populations. These insights highlight the urgent need for ongoing surveillance and the development of effective strategies to curb the proliferation of antibiotic resistance.

Genome analyses of colistin-resistant high-risk blaNDM-5 producing Klebsiella pneumoniae ST147 and Pseudomonas aeruginosa ST235 and ST357 in clinical settings

BACKGROUND

Colistin is a last-resort antibiotic used in extreme cases of multi-drug resistant (MDR) Gram-negative bacterial infections. Colistin resistance has increased in recent years and often goes undetected due to the inefficiency of predominantly used standard antibiotic susceptibility tests (AST). To address this challenge, we aimed to detect the prevalence of colistin resistance strains through both Vitek®2 and broth micro-dilution. We investigated 1748 blood, tracheal aspirate, and pleural fluid samples from the Intensive Care Unit (ICU), Neonatal Intensive Care Unit (NICU), and Tuberculosis and Respiratory Disease centre (TBRD) in an India hospital. Whole-genome sequencing (WGS) of extremely drug-resitant (XDR) and pan-drug resistant (PDR) strains revealed the resistance mechanisms through the Resistance Gene Identifier (RGI.v6.0.0) and Snippy.v4.6.0. Abricate.v1.0.1, PlasmidFinder.v2.1, MobileElementFinder.v1.0.3 etc. detected virulence factors, and mobile genetic elements associated to uncover the pathogenecity and the role of horizontal gene transfer (HGT).

RESULTS

This study reveals compelling insights into colistin resistance among global high-risk clinical isolates: Klebsiella pneumoniae ST147 (16/20), Pseudomonas aeruginosa ST235 (3/20), and ST357 (1/20). Vitek®2 found 6 colistin-resistant strains (minimum inhibitory concentrations, MIC = 4 μg/mL), while broth microdilution identified 48 (MIC = 32-128 μg/mL), adhering to CLSI guidelines. Despite the absence of mobile colistin resistance (mcr) genes, mechanisms underlying colistin resistance included mgrB deletion, phosphoethanolamine transferases arnT, eptB, ompA, and mutations in pmrB (T246A, R256G) and eptA (V50L, A135P, I138V, C27F) in K. pneumoniae. P. aeruginosa harbored phosphoethanolamine transferases basS/pmrb, basR, arnA, cprR, cprS, alongside pmrB (G362S), and parS (H398R) mutations. Both strains carried diverse clinically relevant antimicrobial resistance genes (ARGs), including plasmid-mediated blaNDM-5 (K. pneumoniae ST147) and chromosomally mediated blaNDM-1 (P. aeruginosa ST357).

CONCLUSION

The global surge in MDR, XDR and PDR bacteria necessitates last-resort antibiotics such as colistin. However, escalating resistance, particularly to colistin, presents a critical challenge. Inefficient colistin resistance detection methods, including Vitek2, alongside limited surveillance resources, accentuate the need for improved strategies. Whole-genome sequencing revealed alarming colistin resistance among K. pneumoniae and P. aeruginosa in an Indian hospital. The identification of XDR and PDR strains underscores urgency for enhanced surveillance and infection control. SNP analysis elucidated resistance mechanisms, highlighting the complexity of combatting resistance.

Vitamin D and vitamin K1 as novel inhibitors of biofilm in Gram-negative bacteria

BACKGROUND

The persistent surge in antimicrobial resistance represents a global disaster. The initial attachment and maturation of microbial biofilms are intimately related to antimicrobial resistance, which in turn exacerbates the challenge of eradicating bacterial infections. Consequently, there is a pressing need for novel therapies to be employed either independently or as adjuvants to diminish bacterial virulence and pathogenicity. In this context, we propose a novel approach focusing on vitamin D and vitamin K1 as potential antibiofilm agents that target Gram-negative bacteria which are hazardous to human health.

RESULTS

Out of 130 Gram-negative bacterial isolates, 117 were confirmed to be A. baumannii (21 isolates, 17.9%), K. pneumoniae (40 isolates, 34.2%) and P. aeruginosa (56 isolates, 47.9%). The majority of the isolates were obtained from blood and wound specimens (27.4% each). Most of the isolates exhibited high resistance rates to β-lactams (60.7-100%), ciprofloxacin (62.5-100%), amikacin (53.6-76.2%) and gentamicin (65-71.4%). Approximately 93.2% of the isolates were biofilm producers, with 6.8% categorized as weak, 42.7% as moderate, and 50.4% as strong biofilm producers. The minimum inhibitory concentrations (MICs) of vitamin D and vitamin K1 were 625-1250 µg mL-1 and 2500-5000 µg mL-1, respectively, against A. baumannii (A5, A20 and A21), K. pneumoniae (K25, K27 and K28), and P. aeruginosa (P8, P16, P24 and P27) clinical isolates and standard strains A. baumannii (ATCC 19606 and ATCC 17978), K. pneumoniae (ATCC 51503) and P. aeruginosa PAO1 and PAO14. Both vitamins significantly decreased bacterial attachment and significantly eradicated mature biofilms developed by the selected standard and clinical Gram-negative isolates. The anti-biofilm effects of both supplements were confirmed by a notable decrease in the relative expression of the biofilm-encoding genes cusD, bssS and pelA in A. baumannii A5, K. pneumoniae K28 and P. aeruginosa P16, respectively.

CONCLUSION

This study highlights the anti-biofilm activity of vitamins D and K1 against the tested Gram-negative strains, which emphasizes the potential of these vitamins for use as adjuvant therapies to increase the efficacy of treatment for infections caused by multidrug-resistant (MDR) strains and biofilm-forming phenotypes. However, further validation through in vivo studies is needed to confirm these promising results.

Pseudomonas aeruginosa and related antibiotic resistance genes as indicators for wastewater treatment

This review aims to examine the existence of Pseudomonas aeruginosa (P. aeruginosa) and their antibiotic resistance genes (ARGs) in aquatic settings and the alternative treatment ways. P. aeruginosa in a various aquatic environment have been identified as contaminants with impacts on human health and the environment. P. aeruginosa resistance to multiple antibiotics, such as sulfamethoxazole, ciprofloxacin, quinolone, trimethoprim, tetracycline, vancomycin, as well as specific antibiotic resistance genes including sul1, qnrs, blaVIM, blaTEM, blaCTX, blaAIM-1, tetA, ampC, blaVIM. The development of resistance can occur naturally, through mutations, or via horizontal gene transfer facilitated by sterilizing agents. In addition, an overview of the current knowledge on inactivation of Pseudomonas aeruginosa and ARG and the mechanisms of action of various disinfection processes in water and wastewater (UV chlorine processes, catalytic oxidation, Fenton reaction, and ozonation) is given. An overview of the effects of nanotechnology and the resulting wetlands is also given.

Unveiling the ocular battlefield: Insights into Pseudomonas aeruginosa virulence factors and their implications for multidrug resistance

The research investigates the virulence factors of Pseudomonas aeruginosa (P. aeruginosa), a pathogen known for its ability to cause human infections by releasing various exoenzymes and virulence factors. Particularly relevant in ocular infections, where tissue degeneration can occur, even after bacterial growth has ceased due to the potential role of secreted proteins/enzymes. Clinical isolates of P. aeruginosa, both ocular (146) and non-ocular (54), were examined to determine the frequency and mechanism of virulence factors. Phenotypic characterization revealed the production of alginate, biofilm, phospholipase C, and alkaline protease, while genotypic testing using internal uniplex PCR identified the presence of Exo U, S, T, Y, and LasB genes. Results showed a significant prevalence of Exo U and Y genes in ocular isolates, a finding unique to Indian studies. Additionally, the study noted that ocular isolates often contained all four secretomes, suggesting a potential link between these factors and ocular infections. These findings contribute to understanding the pathogenesis of P. aeruginosa infections, particularly in ocular contexts, and highlights the importance of comprehensive virulence factor analysis in clinical settings.

Antioxidant Activity of Humulus lupulus Phenolic Hop Extracts in Creating a New Pâté: An Element Affecting Fat Stability and Microbiological Quality during Storage

The aim of this study was to evaluate the effect of hop extracts on changes in the primary and secondary fat oxidation products, physicochemical properties, and microbiological quality of pâté-type offal sausages obtained through the partial replacement of animal fat with vegetable fat. This study demonstrated that the extraction efficiency varied among hop cone varieties, with the highest efficiency observed for the Lubelski variety and the lowest for the Magnum variety. The phenolic compound content was higher in the Magnum cones (2.74 ± 0.11 mg/g dry matter) compared to the Lubelska cones (2.27 ± 0.05 mg/g of product). Additionally, the DPPH radical scavenging activity was greater in the extract from the Magnum cones (4.21 ± 0.09 mg TE/g d.w.) than in the extract from the Lublelski cones (3.87 ± 0.05 mg TE/ g d.w.). Similarly, the extracts from the Lubelski cones exhibited a higher antiradical activity against the ABTS radical compared to the extract from Magnum cones. Throughout storage, a significant increase in the pH value was observed in the control sample and in the samples with a 20% replacement of animal fat with rapeseed oil and Magnum hop extract. However, the addition of Lubelski hop extract resulted in a decrease in the pH value during the 15-day storage period. The samples with a 20% replacement of animal fat with rapeseed oil and 0.1% Lubelski hop extract showed the least changes in water activity during storage. The samples with a 20% replacement of animal fat with rapeseed oil and the addition of 0.2% Lubelski hop extract had the lowest peroxide value and TBARS index throughout the storage period. The addition of hop extract inhibited the growth of the total number of microorganisms in the tested sausages. In the samples with a 20% replacement of animal fat with rapeseed oil, the content of aerobic microorganisms, compared to the control sample, was statistically significantly lower.

Enterobacter cloacae from urinary tract infections: frequency, protein analysis, and antimicrobial resistance

The genus Enterobacter belongs to the ESKAPE group, which includes Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp. This group is characterized by the development of resistance to various antibiotics. In recent years, Enterobacter cloacae (E. cloacae) has emerged as a clinically important pathogen responsible for a wide range of healthcare-associated illnesses. Identifying Enterobacter species can be challenging due to their similar phenotypic characteristics. The emergence of multidrug-resistant E. cloacae is also a significant problem in healthcare settings. Therefore, our study aimed to identify and differentiate E. cloacae using Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) as a fast and precise proteomic analytical technique. We also tested hospital-acquired E. cloacae isolates that produce Extended-spectrum beta-lactamases (ESBL) against commonly used antibiotics for treating urinary tract infections (UTIs). We used a total of 189 E. cloacae isolates from 2300 urine samples of patients with UTIs in our investigation. We employed culturing techniques, as well as the BD Phoenix™ automated identification system (Becton, Dickinson) and Analytical Profile Index (API) system for the biochemical identification of E. cloacae isolates. We used the MALDI Biotyper (MBT) device for peptide mass fingerprinting analysis of all isolates. We utilized the single peak intensities and Principal Component Analysis (PCA) created by MBT Compass software to discriminate and cluster the E. cloacae isolates. Additionally, we evaluated the sensitivity and resistance of ESBL-E. cloacae isolates using the Kirby Bauer method. Out of the 189 E. cloacae isolates, the BD Phoenix system correctly identified 180 (95.24%) isolates, while the API system correctly identified 165 (87.30%) isolates. However, the MBT accurately identified 185 (98.95%) isolates with a score of 2.00 or higher. PCA positively discriminated the identified E. cloacae isolates into one group, and prominent peaks were noticed between 4230 mass-to-charge ratio (m/z) and 8500 m/z. The ESBL-E. cloacae isolates exhibited a higher degree of resistance to ampicillin, amoxicillin-clavulanate, cephalothin, cefuroxime, and cefoxitin. Several isolates were susceptible to carbapenems (meropenem, imipenem, and ertapenem); however, potential future resistance against carbapenems should be taken into consideration. In conclusion, MALDI-TOF MS is a powerful and precise technology that can be routinely used to recognize and differentiate various pathogens in clinical samples. Additionally, the growing antimicrobial resistance of this bacterium may pose a significant risk to human health.

Resistance profiles, virulence and antimicrobial resistance genes of XDR S. Enteritidis and S. Typhimurium

Avian salmonellosis is concomitant with high financial crises in the poultry industry as well as food-borne illness in man. The present study is designed to investigate the emergence of Salmonella Enteritidis and Salmonella Typhimurium in diseased broilers, resistance profiles, and monitoring virulence and antibiotic resistance genes. Consequently, 450 samples (cloacal swabs, liver, and spleen) were collected from 150 diseased birds from different farms in Giza Governorate, Egypt. Subsequently, the bacteriological examination was done. Afterward, the obtained Salmonella isolates were tested for serogrouping, antibiogram, PCR monitoring of virulence (invA, stn, hilA, and pefA), and antimicrobial resistance genes (blaTEM, blaCTX-M, blaNDM, ermA, sul1, tetA, and aadA1). The total prevalence of Salmonella in the examined diseased broilers was 9.3%, and the highest prevalence was noticed in cloacal swabs. Among the recovered Salmonella isolates (n = 35), 20 serovars were recognized as S. Enteritidis and 15 serovars were identified as S. Typhimurium. Almost 60% of the retrieved S. Enteritidis serovars were extensively drug-resistant (XDR) to seven antimicrobial classes and inherited sul1, blaTEM, tetA, blaCTX-M, ereA, and aadA1 genes. Likewise, 25% of the recovered S. Enteritidis serovars were multidrug-resistant (MDR) to six classes and have sul1, blaTEM, tetA, blaCTX-M, and ereA resistance genes. Also, 66.7% of the retrieved S. Typhimurium serovars were XDR to seven classes and have sul1, blaTEM, tetA, blaCTX-M, ereA, and aadA1 genes. Succinctly, this report underlined the reemergence of XDR S. Typhimurium and S. Enteritidis in broiler chickens. Meropenem and norfloxacin exposed a hopeful antimicrobial activity toward the re-emerging XDR S. Typhimurium and S. Enteritidis in broilers. Moreover, the recurrence of these XDR Salmonella strains poses a potential public health threat.

Using model systems to unravel host-Pseudomonas aeruginosa interactions

Using model systems in infection biology has led to the discoveries of many pathogen-encoded virulence factors and critical host immune factors to fight pathogenic infections. Studies of the remarkable Pseudomonas aeruginosa bacterium that infects and causes disease in hosts as divergent as humans and plants afford unique opportunities to shed new light on virulence strategies and host defence mechanisms. One of the rationales for using model systems as a discovery tool to characterise bacterial factors driving human infection outcomes is that many P. aeruginosa virulence factors are required for pathogenesis in diverse different hosts. On the other side, many host signalling components, such as the evolutionarily conserved mitogen-activated protein kinases, are involved in immune signalling in a diverse range of hosts. Some model organisms that have less complex immune systems also allow dissection of the direct impacts of innate immunity on host defence without the interference of adaptive immunity. In this review, we start with discussing the occurrence of P. aeruginosa in the environment and the ability of this bacterium to cause disease in various hosts as a natural opportunistic pathogen. We then summarise the use of some model systems to study host defence and P. aeruginosa virulence.

Evaluation of Antimicrobial Resistance Profiles of Bacteria Isolated from Biofilm in Meat Processing Units

The aim of this study was to assess the hygiene of pork, beef, and poultry carcasses and to determine the phenotypic antibiotic susceptibility of the bacteria embedded in the biofilm formed on the carcasses kept in cooling chambers for at least three days. The level of hygiene was assessed by determining the total aerobic colony count (TACC) and the Enterobacteriaceae level in different sampling points of the carcasses, along with the detection of E. coli and Pseudomonas spp. embedded in the biofilm. Furthermore, the E. coli and Pseudomonas spp. isolates were tested for antimicrobial resistance profiles. A total of 130 samples collected from pork, beef, and poultry from processing units were analyzed to determine the total aerobic colony count as well as to measure the level of Enterobacteriaceae found on the carcasses. The antimicrobial susceptibility of 44 Escherichia coli and eight Pseudomonas spp. strains isolated from the carcasses were assessed using the Vitek 2 system using two different cards. Overall, the regulatory limits for the TACC were exceeded in 7.6% of the samples, and 65% of the samples exceeded the regulatory limits for Enterobacteriaceae levels. The antimicrobial susceptibility tests of the E. coli isolates analyzed with the AST-GN27 card revealed the highest resistance to be that towards ampicillin (76.1%), followed by cefazolin (71.4%), amoxicillin/clavulanic acid (61.9%), nitrofurantoin (52.3%), cefoxitin (47.6%), tetracycline (38.1%), piperacillin, norfloxacin (19%), trimethoprim-sulfamethoxazole (11.9%), cefotaxime (9.5%), ceftazidime, cefazolin, amikacin, gentamicin, and ciprofloxacin (4.7%). However, all of the isolates were sensitive to piperacillin-tazobactam and imipenem. Thirty-two (61.5%; 95% CI 47.9-73.5) out of fifty-two isolates exhibited multidrug resistance, resulting in the expression of 10 resistance profiles. The findings of this study highlight serious hygienic and sanitary deficiencies within the meat processing units and demonstrate that the resulting meat can harbor Multidrug-resistant Escherichia coli and Pseudomonas spp., both of which pose a serious public health risk. However, further research with a larger number of samples is required to reach thorough results.

Prevalence and antimicrobial resistance profile of bacterial foodborne pathogens in Nile tilapia fish (Oreochromis niloticus) at points of retail sale in Nairobi, Kenya

Proteus spp., Staphylococcus spp., Pseudeomonas spp., and pathogenic Vibrios are among the major foodborne pathogens associated with the consumption of contaminated fish. The increasing occurrence of antimicrobial resistance in these pathogens is a serious public health concern globally and therefore continuous monitoring of antimicrobial resistance of these bacteria along the food chain is crucial for for control of foodborne illnesses. The aim of this study was to assess the prevalence, antimicrobial resistance patterns, antibiotic resistance genes, and genetic diversity of bacterial foodborne pathogens recovered from fresh Nile tilapia (Oreochromis niloticus) obtained from retail markets in Nairobi, Kenya. A total of 68 O. niloticus fish with an average weight of 300.12 ± 25.66 g and body length of 23.00 ± 0.82 cm were randomly sampled from retail markets and tested for the presence of Proteus, Staphylococcus aureus, Pseudomonas aeruginosa, Vibrio cholerae, and Vibrio parahaemolyticus. Standard culture-based microbiological and Kirby-Bauer agar disk diffusion methods were used to isolate and determine the antimicrobial resistance patterns of the isolates to 11 selected antibiotics. Statistical analysis was performed using Minitab v17.1, with p < 0.05 considered significant. The genetic diversity of the multidrug-resistant (MDR) and extensively drug-resistant (XDR) bacteria was determined using 16S rRNA sequencing and phylogenetic analysis, and polymerase chain reaction (PCR) was used for detection of antibiotic resistance genes in MDR bacterial isolates. High levels of bacterial contamination were detected in fresh O. niloticus fish (44/68, 64.71%). The most prevalent bacteria were Proteus spp. (44.12%), with the rest of the bacterial species registering a prevalence of 10.29%, 4.41%, 2.94%, and 2.94% (for S. aureus, P. aeruginosa, V. cholerae, and V. parahaemolyticus, respectively). Antimicrobial resistance was detected in all the bacteria species and all the isolates were resistant to at least one antibiotic except cefepime (30 µg). Additionally, 86.36% of the isolates exhibited multidrug resistance, with higher multiple antibiotic resistance indices (MAR index >0.3) indicating that fresh O. niloticus fish were highly contaminated with MDR bacteria. Results of 16S rRNA sequences, BLASTn analysis, and phylogenetic trees confirmed the identified MDR bacterial isolates as Proteus mirabilis and other Proteus spp., S. aureus, P. aeruginosa, V. cholerae, and V. parahaemolyticus. PCR analysis confirmed the presence of multiple antibiotic resistance genes blaTEM-1, blaCMY-2, tetA, tetC, Sul2, dfrA7, strA, and aadA belonging to β-lactamases, tetracycline, sulfonamide, trimethoprim, and aminoglycosides in all the MDR bacterial isolates. There was strong correlation between antibiotic- resistant genes and phenotypic resistance to antibiotics of MDR bacteria. This study showed high prevalence of multidrug resistance among foodborne bacterial isolates from fresh O. niloticus fish obtained from retail markets. From this study, we conclude that fresh O. niloticus fish are a potential source of MDR bacteria, which could be a major risk to public health as a consequence of their dissemination along the human food chain. These results highlight the prevalence of antimicrobial-resistant foodborne pathogens in fish purchased from retail markets and underscore the risk associated with improper handling of fish.

Bacterial Skin Microbiota of Seabass from Aegean Fish Farms and Antibiotic Susceptibility of Psychrotrophic Pseudomonas

Farming seabass (Dicentrarchus labrax) is an essential activity in the Mediterranean basin including the Aegean Sea. The main seabass producer is Turkey accounting for 155,151 tons of production in 2021. In this study, skin swabs of seabass farmed in the Aegean Sea were analysed with regard to the isolation and identification of Pseudomonas. Bacterial microbiota of skin samples (n = 96) from 12 fish farms were investigated using next-generation sequencing (NGS) and metabarcoding analysis. The results demonstrated that Proteobacteria was the dominant bacterial phylum in all samples. At the species level, Pseudomonas lundensis was identified in all samples. Pseudomonas, Shewanella, and Flavobacterium were identified using conventional methods and a total of 46 viable (48% of all NGS+) Pseudomonas were isolated in seabass swab samples. Additionally, antibiotic susceptibility was determined according to standards of the European Committee on Antimicrobial Susceptibility Testing (EUCAST) and Clinical and Laboratory Standards Institute (CLSI) in psychrotrophic Pseudomonas. Pseudomonas strains were tested for susceptibility to 11 antibiotics (piperacillin-tazobactam, gentamicin, tobramycin, amikacin, doripenem, meropenem, imipenem, levofloxacin, ciprofloxacin, norfloxacin, and tetracycline) from five different groups of antibiotics (penicillins, aminoglycosides, carbapenems, fluoroquinolones, and tetracyclines). The antibiotics chosen were not specifically linked to usage by the aquaculture industry. According to the EUCAST and CLSI, three and two Pseudomonas strains were found to be resistant to doripenem and imipenem (E-test), respectively. All strains were susceptible to piperacillin-tazobactam, amikacin, levofloxacin, and tetracycline. Our data provide insight into different bacteria that are prevalent in the skin microbiota of seabass sampled from the Aegean Sea in Turkey, and into the antibiotic resistance of psychrotrophic Pseudomonas spp.

Enhancing the targeting performance and prolonging the antibacterial effects of clove essential oil liposomes to Campylobacter jejuni by antibody modification

The application of plant essential oil liposomes to prevent and control food safety risks caused by Campylobacter jejuni (C. jejuni) still faces challenges such as lack of targeting and low release rate. Here, a bacteria-targeted and protease-activated antibacterial liposome (ACCLPs) was successfully synthesized through encapsulation of clove essential oil (CEO) by film dispersion method, embedding of casein by freeze-thaw method, and conjugation of C. jejuni antibody on the liposome membrane by post-insertion method. The average particle size, the essential oil encapsulation rate, the casein mosaic rate, and the antibody coupling efficiency of ACCLPs were determined as185.87 nm,16.9%,70.1% and 87.5%, respectively. The modification with C. jejuni antibody could significantly improve the targeting of ACCLPs to C. jejuni. Controlled release experiments showed that the exocrine protease from C. jejuni could hydrolyze the embedded casein and perforation on the ACCLPs, thus leading to a bacteria-dependent CEO release and significant prolonging the antibacterial effects of ACCLPs. Application results of ACCLPs on C. jejuni-contaminated foods showed that ACCLPs could effectively inhibit C. jejuni in a variety of meat products, fruits and vegetables and extend their shelf life without significantly affecting food quality. The results above in this work would provide a new view for the development of high efficient liposome-based antibacterial system of plant essential oil.

Investigation of antimicrobial resistance patterns and molecular typing of Pseudomonas aeruginosa isolates among Coronavirus disease-19 patients

BACKGROUND

Pseudomonas aeruginosa is a common co-infecting pathogen recognized among COVID-19 patients. We aimed to investigate the antimicrobial resistance patterns and molecular typing of Pseudomonas aeruginosa isolates among Coronavirus disease-19 patients.

METHODS

Between December 2020 and July 2021, 15 Pseudomonas aeruginosa were isolated from COVID-19 patients in the intensive care unit at Sina Hospital in Hamadan, west of Iran. The antimicrobial resistance of the isolates was determined by disk diffusion and broth microdilution methods. The double-disk synergy method, Modified Hodge test, and polymerase chain reaction were utilized to detect Pseudomonas aeruginosa extended spectrum beta-lactamase and carbapenemase producers. Microtiter plate assay was performed to evaluate the biofilm formation ability of the isolates. The isolates phylogenetic relatedness was revealed using the multilocus variable-number tandem-repeat analysis method.

RESULTS

The results showed Pseudomonas aeruginosa isolates had the most elevated resistance to imipenem (93.3%), trimethoprim-sulfamethoxazole (93.3%), ceftriaxone (80%), ceftazidime (80%), gentamicin (60%), levofloxacin (60%), ciprofloxacin (60%), and cefepime (60%). In the broth microdilution method, 100%, 100%, 20%, and 13.3% of isolates showed resistance to imipenem, meropenem, polymyxin B, and colistin, respectively. Ten (66.6%) isolates were identified as multiple drug resistance. Carbapenemase enzymes and extended spectrum beta-lactamases were identified in 66.6% and 20% of the isolates, respectively and the biofilm formation was detected in 100% of the isolates. The blaOXA-48, blaTEM, blaIMP, blaSPM, blaPER, blaVEB, blaNDM, blaSHV, and blaCTX-M genes were detected in 100%, 86.6%, 86.6%, 40%, 20%, 20%, 13.3%, 6.6%, and 6.6% of the isolates, respectively. The blaVIM, blaGIM, blaGES, and blaMCR-1 genes were not identified in any of the isolates. The MLVA typing technique showed 11 types and seven main clusters and most isolates belong to cluster I, V and VII.

CONCLUSION

Due to the high rate of antimicrobial resistance, as well as the genetic diversity of Pseudomonas aeruginosa isolates from COVID-19 patients, it is indispensable to monitor the antimicrobial resistance pattern and epidemiology of the isolates on a regular basis.

Prevalence and Antibiotic Resistance Phenotypes of Pseudomonas spp. in Fresh Fish Fillets

In fresh fish products, excessive loads of Pseudomonas can lead to their rapid spoilage. It is wise for Food Business Operators (FBOs) to consider its presence both in whole and prepared fish products. With the current study, we aimed to quantify Pseudomonas spp. in fresh fillets of Salmo salar, Gadus morhua and Pleuronectes platessa. For all three fish species, we detected loads of presumptive Pseudomonas no lower than 10⁴-10⁵ cfu/g in more than 50% of the samples. We isolated 55 strains of presumptive Pseudomonas and carried out their biochemical identification; 67.27% of the isolates were actually Pseudomonas. These data confirm that fresh fish fillets are normally contaminated with Pseudomonas spp. and the FBOs should add it as a "process hygiene criterion" according to EC Regulation n.2073/2005. Furthermore, in food hygiene, it is worth evaluating the prevalence of antimicrobial resistance. A total of 37 Pseudomonas strains were tested against 15 antimicrobials, and they all were identified as being resistant to at least one antimicrobial, mainly penicillin G, ampicillin, amoxicillin, tetracycline, erythromycin, vancomycin, clindamycin and trimethoprim. As many as 76.47% of Pseudomonas fluorescens isolates were multi-drug resistant. Our results confirm that Pseudomonas is becoming increasingly resistant to antimicrobials and thus should be continuously monitored in foods.

oprL Gene Sequencing, Resistance Patterns, Virulence Genes, Quorum Sensing and Antibiotic Resistance Genes of XDR Pseudomonas aeruginosa Isolated from Broiler Chickens

Background

Pseudomonas aeruginosa is incriminated in septicemia, significant economic losses in the poultry production sector, and severe respiratory infections in humans. This study aimed to investigate the occurrence, oprL sequencing, antimicrobial resistance patterns, virulence-determinant, Quorum sensing, and antibiotic resistance genes of P. aeruginosa retrieved from broiler chickens.

Methods

Two hundred samples were collected from 120 broiler chickens from broiler farms at Ismailia Governorate, Egypt. Consequently, the bacteriological examination was conducted and the obtained P. aeruginosa strains were tested for oprL gene sequencing, antibiogram, and PCR screening of virulence, Quorum sensing, and antibiotic resistance genes.

Results

The overall prevalence of P. aeruginosa in the examined birds was 28.3%. The oprL gene sequence analysis underlined that the tested strain expressed a notable genetic identity with various P. aeruginosa strains isolated from different geographical areas in the USA, India, China, Chile, and Ghana. PCR evidenced that the obtained P. aeruginosa strains, carrying virulence-related genes: oprL, toxA, aprA, phzM, and exoS in a prevalence of 100%, 100%, 42.5%, 33.3%, and 25.9%, respectively. Moreover, the recovered P. aeruginosa strains possessed the Quorum sensing genes: lasI, lasR, rhlI, and rhlR in a prevalence of 85.2%, 85.2%, 81.5%, and 81.5%, respectively. Furthermore, 40.7% of the isolated P. aeruginosa were XDR to seven antimicrobial classes, possessing sul1, bla _TEM, tetA, bla _CTX-M, bla _OXA-1, and aadA1 genes.

Conclusion

As we can tell, this is the first report emphasizing the evolution of XDR P. aeruginosa strains from broiler chicken in Egypt, which is supposed to be a serious threat to public health. The emerging XDR P. aeruginosa in poultry frequently harbored the oprL, toxA, and aprA virulence genes, the lasI, lasR, rhlI, and rhlR Quorum sensing genes, and the sul1, bla _TEM, tetA, bla _CTXM, bla _OXA-1, and aadA1 resistance genes.

In Vitro and In Situ Characterization of Psychrotrophic Spoilage Bacteria Recovered from Chilled Chicken

Spoilage bacteria play a remarkable role in the spoilage of chilled chicken. In this paper, a total of 42 isolates belonging to 16 species of four genera were isolated from chilled chicken and displayed different characterizations of psychrotrophic spoilage. Six isolates of J7, J8, Q20, Q23, R1, and R9 with differences in proteolytic capabilities were further characterized for in situ spoilage potential evaluation. Pseudomonas lundensis J8 exhibited the strongest spoilage potential in situ, displaying a fast growth rate, increased pH velocity, high total volatile basic nitrogen, and high peptide content in the chicken samples. The volatile flavor analysis of chicken samples via electronic nose indicated that the content of characteristic odors representing spoilage, including sulfides, organic sulfide, and hydride, increased during storage. Additionally, the principle component and correlation analyses revealed that the spoilage odors produced by different species of bacteria were significantly different and positively correlated with the results of protease activity in vitro. The characteristics of spoilage bacteria in chilled chicken provided a comprehensive insight into microbial assessment during storage.

Microbiological and Sensorial Quality of Beef Meat (Longissimus dorsi) Marinated with Cinnamon Extract and Stored at Various Temperatures

Meat spoilage caused by temperature abuse is a major problem for producers, retailers, and consumers that can generate large economic losses to industries. Microbial growth of Pseudomonas spp. is the main source of spoilage during storage. Cinnamon has antimicrobial properties that may potentially be used to reduce the spoilage caused by Pseudomonas. The objectives of this study were to determine the inhibitory effect of cinnamon extract (CE) against Pseudomonas aeruginosa (ATCC 27853) and evaluate the treatment of CE on meat quality during different storage temperatures (5 °C, 10 °C, 15 °C, and 25 °C). The anti-Pseudomonas result showed that 100% (w/v) CE concentration produced a 13.50 mm zone of inhibition in a disc diffusion assay. The minimum inhibitor concentration (MIC) of CE was noted at 25% (v/v), whereas the minimum bactericidal concentration (MBC) value was observed at 50% (v/v) concentration of CE. The time-kill showed the growth of P. aeruginosa decreased from 7.64 to 5.39 log CFU/mL at MIC concentration. Total phenolic content and IC₅₀ value of the cinnamon extract was expressed as 6.72 ± 0.87 mg GAE/g extract and 0.15 mg/mL, respectively. When the meat was marinated with 50% (v/v) CE and stored at various temperatures, the total viable count (TVC) and growth of Pseudomonas spp. were lowered as compared to the control sample. However, the reduction in microbial count in all samples was influenced by the storage temperature, where the lowered microbial count was noted in the sample treated with CE and stored at 5 and 10 °C for 48 h. The pH of meat treated with or without CE ranged from pH 5.74 to 6.48. The sensory attributes of colour, texture, and overall acceptability have a significant difference, except for odour, between marinated meat and control. The results indicate that the use of cinnamon extract as the marination agent for meat could reduce the growth of Pseudomonas spp. and therefore assist in extending the shelf life of meat at 5 and 10 °C storage temperatures.