Antimicrobial Profiles Research Articles

A new de novo‐assisted mass spectrometry method for novel antimicrobial peptide expression profiling in cerebrospinal fluid (CSF) of demented subjects

AbstractBackgroundActivation of innate immunity is a pathological hallmark of Alzheimer’s disease (AD). Antimicrobial peptides (AMPs), small (12‐50 amino acid) peptides, are essential components of the innate immune system and provide the first line of defense against microbial infections in immune‐privileged tissues, like brain. Many proteins with antimicrobial activity have been shown to be involved in AD. We developed a new mass spectrometry (MS)‐based method to profile known and novel AMPs in CSF. Here we report differentially expressed AMPs in CSF of Ab+ (AD) and Ab‐ (non‐AD) dementia.MethodWe created a custom (Swiss‐Prot + human AMP) database for our de novo‐assisted proteomics platform. MS data (PRIDE archive PXD016278) from CSF of cognitively impaired subjects with or without amyloid positivity were analyzed. Peptide raw peak area intensities were quantile normalized and log2 transformed to reduce technical variation and ensure distribution symmetry. Differentially expressed peptides were identified via analysis of covariance after adjusting for age and gender, with the significant criteria based on 20% false discovery rate. Multiscale Embedded Gene Co‐expression Network Analysis (MEGENA) was used to identify AMPs with the potential to regulate the molecular changes in AD.ResultWe identified 24 differentially expressed AMPs in CSF of Ab‐driven dementia mapping to 6 proteins. These include the AMPs released by the chromaffin cells of the adrenal medulla (Chromogranin A and B, Ubiquitin), Beta‐2 macroglobulin, Amyloid‐beta A4, and Clustrin proteins. The antimicrobial activity containing sequence from Chromogranin A was represented in top two modules identified by MEGENA network analysis. These modules exhibited high correlation with peptides from a dementia‐linked neurosecretory protein VGF. The top 5 pathways enriched in MEGENA modules include cell adhesion, system development, nervous system development, regulation of nervous system development, and neurogenesis.ConclusionThis study reports the first unbiased analysis of dementia‐linked AMP diversity that can be monitored in CSF. Contribution of these AMPs and the associated pathways in the AD pathophysiology warrants further investigation.

ORGANISMS RESPONSIBLE FOR TOTAL KNEE PROSTHETIC JOINT INFECTION: A SAUDITERTIARY CENTER 10-YEAR-EXPERIENCE

Background: Total Knee arthroplasty (TKA) is a standard procedure to treat end-stage knee osteoarthritis. As with any surgery, complications may arise, and one of the common complications reported from knee replacement procedures is infection. In this study, we aimed to retrospectively determine the prevalence of the infections pathogens following TKA and identify the most common microorganisms involved in infections in knee arthroplasty. Methods: Data were gathered from archived medical files using a retrospective descriptive study methodology. The current study included patients who underwent total knee arthroplasty and experienced infections between 2007 and 2017 at King Abdul-Aziz Medical City (KAMC), Jeddah, Saudi Arabia. Results: Out of 56 patients, almost half were hypertensive (57.1%) and diabetic (46.4%). 51.8% of patients had bilateral TKA. Among the patients, a third (41.8%)had pain the primary organism identified was Staphylococcus (44.65%), and 20% of cases involved co-infection with another organism. 16% of patients had methicillin-resistant Staphylococcus aureus. Infections with pseudomonas, brucellosis, and tuberculosis were also present in 17.9%, 3.6%, and 1.8% of the patients, respectively. Conclusion: Staphylococci were identified as the primary organism responsible for prostheticknee infection in KAMC patients. We recommend a focus on staphylococci in both prophylactic and empirical antibiotic treatments. Additional multicenter studies examining larger sample sizes are required to identify other factors influencingProsthetic Joint Infection (PJI), including obtaining information on the patients antimicrobial sensitivity profiles and geographic factors.

Frequency and Antimicrobial Resistance Patterns of Foodborne Pathogens in Ready-to-Eat Foods: An Evolving Public Health Challenge

Food products that are ready-to-eat have become increasingly popular in recent years due to their efficiency, affordability, and convenience. However, there are concerns about public health because certain products, particularly animal products, may contain antibiotic-resistant bacteria. This study aimed to quickly and accurately identify foodborne pathogens, such as Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), in samples of shawarma and chicken burgers using peptide mass fingerprinting (PMF) technology. Additionally, the prevalence and levels of antibiotic resistance in the pathogens were determined. The study utilized 300 samples obtained from fast food restaurants in Al Qassim, Saudi Arabia. A variety of methods were used to identify foodborne pathogens, including culture on specific media, bacterial counts by numerical dilutions of homogenized samples, and proteome identification by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The Kirby–Bauer method was applied to detect the susceptibility and resistance of the bacteria to various antibiotics. PCR was utilized to identify antimicrobial resistance genes such as blaTEM, tet(A), blaZ, and mecA in S. aureus and E. coli isolates. The percentage of E. coli, S. aureus, Salmonella, Listeria monocytogenes (L. monocytogenes), Acinetobacter baumannii (A. baumannii), and Hafnia alevei (H. alevei) was 34%, 31%, 10.67%, 7.33%, 6.67%, and 4%, respectively. Shawarma samples were found to contain the highest levels of pathogens, compared with chicken burger samples. According to the MBT Compass Flex Series Version 1.3 software, all isolates were identified with 100% accuracy. The log score for MBT identification ranged from 2.00 to 2.56. Among E. coli isolates, ampicillin, and penicillin had the highest resistance rate (100%), followed by tetracycline (35.29%). A number of antibiotics were reported to be resistant to S. aureus, including nalidixic acid (100%), followed by penicillin (96.77%), piperacillin (45.16%), and norfloxacin (32.26%). Some E. coli isolates were susceptible to tetracycline (49.02%), nalidixic acid (47.06%), and piperacillin (43.14%), whereas amikacin was the only drug that was effective against 32.72% of S. aureus isolates. The proportions of the blaTEM and tet(A) genes in E. coli isolates were 55.89% and 45.1%, respectively, whereas S. aureus strains did not possess either of these genes. However, 21.5% and 47.31% of blaz and mecA genes were present among various isolates of S. aureus, respectively. In contrast, E. coli strains did not possess either of these genes. In conclusion, the fast identification and antimicrobial profiles of the foodborne pathogens were useful in identifying which restaurants and fast food outlets may need to improve their food safety practices. Ultimately, our results will be used to devise targeted strategies to control foodborne pathogens.

Exploring Antimicrobial Resistance Profiles of E. coli Isolates in Dairy Cattle: A Baseline Study across Dairy Farms with Varied Husbandry Practices in Puerto Rico.

Antimicrobial treatment in livestock can contribute to the emergence and spread of antimicrobial-resistant (AMR) microorganisms. Despite substantial surveillance of AMR bacteria in the continental United States, the prevalence of these AMR organisms in U.S. territories, such as Puerto Rico, remains understudied. The goals of this research included obtaining baseline data on the antimicrobial profile of E. coli isolates from Puerto Rico dairy farms with different husbandry practices. Seventy-nine fecal samples were collected from two types of conventional dairy farms: those that fed calves with tank milk and those that fed calves with waste milk. These samples were collected from the animals' rectums, culture, and subsequently confirmed through biochemical tests. Out of these samples, 32 isolates were analyzed phenotypically and genotypically to elucidate their AMR profiles. The results underscore a discrepancy in the occurrence of antimicrobial resistance genes between calves and adult cattle. Notably, waste milk-fed calves exhibited a significantly higher prevalence of antibiotic-resistant E. coli when compared to their tank milk-fed counterparts. These disparities emphasize the need for more comprehensive investigations to determine causative factors. These results underscore the urgency of comprehensive strategies to raise awareness about how management practices influence antimicrobial resistance, shifting the focus from treatment to prevention.

Prevalence of ventilator-associated events and antibiogram of bacterial isolates of ventilator-associated pneumonia in a tertiary care hospital of Uttarakhand.

Despite progress in diagnosing and managing ventilator-associated pneumonia (VAP), ongoing monitoring of ventilator-associated events (VAE) is crucial due to VAP's persistent prominence as the primary cause of Hospital-Acquired Infection (HAI) among Intensive Care unit patients. This study was done to illuminate the prevalence of VAE and antibiogram of bacterial isolates of VAP in a tertiary care hospital of Uttarakhand. This cross-sectional study focused on ICU patients. Adult patients ventilated for > 2 days were monitored daily, with VAE data analyzed using Center of Disease Control & Prevention (CDC) criteria. Specimens were sent to the Microbiology Department and cultured on Blood agar and MacConkey agar. Identification and antimicrobial profiles of isolates were determined using Vitek-2 Compact. 1220 ventilated individuals were assessed in total. VAE was diagnosed in 6.4% (78/1220) of the patients, the same later developed ventilator associated condition (VAC), 74 developed the infection-related VAC (IVAC), and 60 developed the possible/probable VAP (PVAP) among the 78 VAE cases. Klebsiella pneumoniae (35%), Acinetobacter baumannii (33%), and Pseudomonas aeruginosa (16%) were the most common isolated organisms. Colistin (57%) was the most effective against Klebsiella pneumoniae, followed by amikacin (28.5%) and trimethoprim+sulfamethoxazole (24%). Pseudomonas aeruginosa was most susceptible to imipenem (70%), meropenem, cefoperazone+sulbactam, and colistin (60%). Acinetobacter baumannii was most susceptible to colistin (85%), tigecycline (65%), and trimethoprim+sulfamethoxazole (25%). The most common cause of HAI is VAP. The purpose of this study is to determine the importance of starting suitable antibiotics early for prognosis and the difficulty of diagnosing VAP.

Indeno[1,2‐b]pyridin‐5‐one derivatives containing azo groups and their hydrazonal precursors: Synthesis, antimicrobial profile, DNA gyrase binding affinity, and molecular docking

AbstractThe prevalence of germs that are resistant to many antibiotics is rising rapidly the world over. There is a large group of researchers actively looking for better medicines. Here, we designed two series of hydrazonal and indeno[1,2‐b]pyridin‐5‐one bearing hydrazone and azo‐groups to test their antimicrobial activity. Molecular structures of all derivatives were assured based on their spectral data and elemental analyses. Results of the antimicrobial activity of the tested hydrazone and azo compounds showed promising potential for several derivatives. The minimum inhibitory concentrations (MICs) of hydrazones 4a‐h and 6a‐g displayed good antibacterial reactivities with a range of 3.91–250 μg/mL and moderate antifungal activity with a range of 15.6–500 μg/mL. The most promising hydrazone 4f and azo‐6a compounds demonstrated MIC values against Streptococcus faecalis and Escherichia coli equal to 3.91 and 7.81 μg/mL, respectively. Moreover, azo compound 6a showed MIC value equal to 3.91 μg/mL against Enterobacter cloacae species. Additionally, derivative 4f exhibited a significant inhibitory profile against the E. coli gyrase A enzyme (IC50 = 5.53 μg/mL). On the other hand, compound 6a (IC50 14.05 μg/mL) exhibited the lowest DNA gyrase inhibitory activity as compared to compounds 4f and reference standard drug novobiocin, IC50 5.53 and 1.88 μg/mL, respectively. Pharmacokinetic and pharmacodynamic profiles and molecular docking studies for the two most promising molecules 4f and 6a were computed and revealed that both compounds have good ADME profiles and high binding affinity to DNA gyrase binding site.

Antimicrobial susceptibility profile of Neisseria gonorrhoeae from patients attending a medical laboratory, Institut Pasteur de Madagascar between 2014 and 2020: phenotypical and genomic characterisation in a subset of Neisseria gonorrhoeae isolates

ObjectivesAntimicrobial-resistant Neisseria gonorrhoeae (NG) is a concern. Little is known about antimicrobial susceptibility profiles and associated genetic resistance mechanisms of NG in Madagascar. We report susceptibility data of NG isolates...

Progressive ulcerative keratitis in dogs in the United Kingdom: Microbial isolates, antimicrobial sensitivity, and resistance patterns.

The objective of the study was to identify bacterial pathogens and their antimicrobial sensitivity profile associated with cases of canine progressive ulcerative keratitis. Analysis of microbial culture and sensitivity results from dogs with progressive ulcerative keratitis presenting to a UK referral practice between December 2018 and August 2020. Positive bacterial cultures were obtained from 80/148 (54%) of the canine ulcers sampled with 99 bacterial isolates cultured. Streptococcus canis (n = 29), Pseudomonas aeruginosa (n = 19), and Staphylococcus pseudintermedius (n = 16) were the most common isolates. Pseudomonas aeruginosa was more likely to be isolated whether the ulcer was clinically malacic at the time of sampling (OR = 10.1, p < .001). Ulcers treated prior to culture with fusidic acid were 7.6 times more likely to be positive than those treated with any other antimicrobial(s). Bacterial isolates demonstrated resistance against neomycin (85%), fusidic acid (78%), and tetracycline (68%). Conversely, isolates were most likely to be sensitive to gentamicin (88%), ofloxacin (77%), ciprofloxacin (73%), and chloramphenicol (64%). Antimicrobial combinations of chloramphenicol or gentamicin with a fluoroquinolone (ofloxacin or ciprofloxacin) or chloramphenicol combined with gentamicin were the most effective on invitro analysis (over 90% susceptibility of all isolates). The most common bacterial species associated with canine progressive ulcerative keratitis in a UK referral population were S. canis, P. aeruginosa, and S. pseudintermedius. Combination antimicrobial therapy is recommended pending culture and sensitivity results given the varied antimicrobial susceptibility profiles and significant bacterial invitro resistance to antimicrobial monotherapy.

Molecular Detection of mec-A Gene and Antimicrobial Profiling of Clinically Associated Staphylococcus aureus

Molecular Detection of mec-A Gene and Antimicrobial Profiling of Clinically Associated Staphylococcus aureus

Antimicrobial Profiling of Resistant Genes in Bacteria Isolated from Drinking Water Sources in Bonny Island, Rivers State, Nigeria

The global health crisis of antimicrobial resistance (AMR) necessitates a profound understanding of its dynamics, particularly in environmental reservoirs such as drinking water sources. The aim of the study was to identify the presence and variety of antibiotic-resistant genes (ARGs) within bacteria isolated from drinking water sources in Bonny Island, Rivers State, Nigeria – an area characterized by unique ecological and human-induced factors. Eighty water samples were collected from drinking water distribution systems within Bonny Island for a period of six month. Bacteria isolated from drinking water samples within Bonny Island underwent antimicrobial profiling, including susceptibility tests against a range of clinically relevant antibiotics. Molecular techniques were employed to identify the isolated bacteria and characterize specific ARGs, illuminating the genetic basis of resistance in the isolated bacteria. The bacterial isolates displayed varying resistance patterns, with the highest resistance observed against cefuroxime (59.6%), cefotaxime (48.9%), ceftazidime (44.7%), ceftriaxone (36.3%), chloramphenicol, and Augmentin (29.8%), while resistance to cotrimoxazole and gentamicin was lower (12.8%). Among the bacterial isolates, the tet gene, conferring resistance to tetracycline antibiotics, was present in 46.7% of cases, while 100% exhibited the oxa gene and 93.3% possessed the aac(6’)-ib gene. Preliminary findings revealed a diverse array of bacteria with varying resistance profiles, including both common and emerging pathogens. The identified ARGs covered genes providing resistance to a broad spectrum of antibiotics, including beta-lactams, fluoroquinolones, and tetracyclines. These results underscore the potential risks associated with the spread of ARGs in drinking water sources and their potential transfer to pathogenic bacteria.

Comparison of genotypic and phenotypic antimicrobial profile in carbapenemases producing Klebsiella pneumoniae.

Prompt administration of appropriate antibiotic therapy is crucial in improving outcomes, particularly in cases sustained by multi-drug resistant strains. Although phenotypic antimicrobial susceptibility testing (AST) represents the gold standard to address antibiotics treatment, the long time required to obtained affordable results could negatively affect the prognosis. In contrast, rapid genotypic AST provide essential information for treatment and surveillance program. In order to evaluate the potential adoption of rapid AST in clinical routine, we compared the genotypic and phenotypic antimicrobial profiles of different K.pneumoniae strains, characterized by different expression of carbapenemases-encoding genes. A set of 109 strains of Cr-Kp were tested for the antimicrobial drugs by the automatized Vitek II system and, in parallel, to the new combination of β-lactams/β-lactamases inhibitors (BL/BLI) by Etest. An antimicrobial resistance index (ARI) was calculated for each strain, assigning each 1 or 0 points based on observed resistance/susceptibility, and dividing the total by the number of antibiotics tested. Kruskal-Wallis test, followed by Dunn's post hoc test (Bonferroni correction), were used to compare quantitative variables among resistance gene subgroups. We observed a higher ARI score in KPC/OXA-48 strains, similar profile in KPC alone and KPC/CTX-M groups and a significant lower resistance in no-carbapenemases-producing group. Same trend was observed in AST for BL/BLI. These preliminary results showed a close link between genotypic and phenotypic AST, supporting the adoption of rapid AST in cases of severe infections, ensuring to saving time and providing, the surveillance of MDR strains and improving stewardship programs.

The whole-genome molecular epidemiology of sequential isolates of Acinetobacter baumannii colonizing the rectum of patients in an adult intensive care unit of a tertiary hospital.

Acinetobacter baumannii is a nosocomial multidrug-resistant pathogen that specifically colonizes and infects patients in intensive care units (ICUs). Genome plasticity of A. baumannii may contribute to the rapid development of A. baumannii resistance during patient treatment. There is little clarity on the dynamics of colonization of A. baumannii in humans. We studied 269 serial isolates of A. baumannii colonizing the rectum of 32 adult patients in an ICU; 5 to 16 isolates were obtained from each patient over a period of weeks to months. The isolates were sequenced using the Illumina platform. Multi-locus sequence typing revealed genetic diversity with 13 sequence types (STs); the dominant ST2 accounted for 202 of the 269 isolates and was isolated from each patient. A core genome comparison of isolates was used to elucidate a detailed understanding of the relationship among isolates within an ST and the genomic relationship among STs. One to three STs were observed in the isolates from each patient. Instances of unchanged colonization, sequential lineage colonization, and colonization with multiple lineages of A. baumannii were seen. The number of resistance genes carried by the isolates varied from 2 to 17. The predominant genes corresponded to those encoding resistance to β-lactam and aminoglycoside antibiotics. Generally, there was a strong correlation between ST and a particular antimicrobial resistance gene profile. This study makes an important baseline contribution to information that will help us understand the role of A. baumannii colonization in the development of opportunistic infections in ICU patients. IMPORTANCE Acinetobacter baumannii is a multidrug-resistant nosocomial pathogen that colonizes and infects debilitated patients in the ICU. There is very little information on the genomic characteristics of colonizing strains. This information is important to understand the evolution of lineages of A. baumannii that develop resistance while patients receive antibiotic treatment in the ICU. Our study demonstrated different patterns of colonization of the rectum of ICU patients with different STs of A. baumannii while one ST colonized all patients. Some STs carried more antibiotic resistance genes compared to others. However, there was a correlation between ST and a particular resistance gene profile. Our results further elucidate the dynamics of enteric colonization of this opportunistic pathogen.

Virulence and Antimicrobial Resistance Gene Profiling of Salmonella Isolated from Swine Meat Samples in Abattoirs and Wet Markets of Metro Manila, Philippines

Virulence and Antimicrobial Resistance Gene Profiling of <i>Salmonella</i> Isolated from Swine Meat Samples in Abattoirs and Wet Markets of Metro Manila, Philippines

Antimicrobial profile of the culturable olive sporobiota and its potential as a source of biocontrol agents for major phytopathogens in olive agriculture.

The phytopathogens Xylella fastidiosa and Verticillium dahliae present an unparalleled threat to olive agriculture. However, there is no efficient field treatment available today for either pest. Spore-forming bacteria (i.e., the sporobiota) are known for their extraordinary resistance properties and antimicrobial activity. The aim of this study was thus to identify potential novel sustainable spore-forming biocontrol agents derived from the culturable olive microbiome, termed the sporobiota, in general and in particular against X. fastidiosa and V. dahliae. We demonstrate the wide-ranging antimicrobial profile of 415 isolates from the culturable olive sporobiota towards human and plant pathogens. We further identified five candidates with antagonistic activity against X. fastidiosa and V. dahliae. These belong to the Bacillus subtilis, Bacillus cereus and Peribacillus simplex clade. The activity was related to the species and their relative origin (soil versus leaf endophytic). It is of particular interest that two of these candidates are already naturally present at the site of disease-development that is, plant interior. We further confirmed the presence of lipopeptide genes potentially associated with the reported bioactivity. The study provides insights into how members of the olive sporobiota may support the olive plant to ward off detrimental pathogens. It further yields five promising candidates for the development of eco-friendly, multi-active biocontrol agents in olive agriculture. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Sociodemographic distributions and molecular characterization of colonized Enterococcus faecium isolates from locality hospitals in Khartoum, Sudan.

Enterococcus faecium is an opportunistic pathogen of humans with diverse hosts, encompassing animals as well as human beings. In the past twenty years, there has been a rise in the instances of nosocomial infections that are linked to antibiotic-resistant Enterococcus faecium. The acquisition of diverse antimicrobial resistance factors has driven the global development of robust and convergent adaptive mechanisms within the healthcare environment. The presence of microorganisms in hospitalized and non-hospitalized patient populations has been significantly aided by the facilitation of various perturbations within their respective microbiomes. This study aimed to determine the antimicrobial profile, demographic and clinical characteristics, along with the detection of virulence encoding genes, and to find out the clonal genetic relationship among colonized E. faecium strains. A hospital-based cross-sectional study was carried out between October 2018 and March 2020 at four Khartoum locality hospitals in Sudan. The study comprised a total of 108 strains of E. faecium isolated from patients admitted to four locality hospitals in Khartoum. A self-structured questionnaire was used to gather information on sociodemographic traits. Data were analyzed using chi-square test. In all cases, P value ≤ 0.05 with a corresponding 95% confidence interval was considered statistically significant. Moreover, enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR) was utilized to assess the prevalence of clonal relationships, and the gel was analyzed using CLIQS software. In this study, the isolation rate of colonized E. faecium strains was 108/170 (63.5%). The colonization of E. faecium and its association with various sociodemographic and clinical features was examined. 73 (67.6%) of patients had multidrug-resistant (MDR), and 22 (20.4%) had extensively drug-resistant (XDR), 73 (67.6%) of patients engaged in self-medication practices. Eighty patients (74.1%) were non-adherence to prescribed antibiotics, while 70 (64.8%) patients reported recent antibiotic usage within the 3 months. The present study suggests that demographic factors may not be significantly associated with the incidence of E. faecium infection except for patients who had a prior history of antibiotic use (P≤0.005). The analysis of virulence genes showed a high prevalence of asa1 gene (22.2%) among strains. In ERIC-PCR the genetic relatedness of E. faecium showed seven identical clusters (A-G) with 100% genetic similarity. This implies clonal propagation in hospitals and communities. This study found that the incidence of E. faecium isolated from locality hospitals in Khartoum was likely due to the spread of E. faecium clones, thereby highlighting the need for intensifying infection control measures to prevent the spreading of nosocomial infection.

Design, synthesis and docking studies of ciprofloxacin analogues as potential antimicrobial agents against resistant pathogens

Antibiotic resistance is one of the leading fears worldwide. Development of resistance against antimicrobial agents is one of the major purposes for research and development of new molecules. Ciprofloxacin analogues have grounds continuous interests and their antibacterial potential is still a focus of research. For this purpose, in present research antibiotic ciprofloxacin (CPFX) has been selected as a parent compound and its analogues has been designed, synthesized and finally evaluated for their better antimicrobial activities. In current research, virtual screening has been performed to analyze the binding energies between the receptor and designed ligands. Those designed ligands showing better binding affinities than parent compound CPFX were short listed for synthesis. The present study also describes in silico prediction of drug-like properties of newly designed analogues by using different computational tools. The in silico screening of designed analogues indicated them qualified for the parameters of drug likeness also showing good bioactivity along with optimum pharmacokinetic properties. Overall results of in silico pharmacokinetic screening indicated that the newly designed compounds may be considered as a candidate for further drug development studies. In order to achieve this objective, six analogues of ciprofloxacin by introducing new functional groups at position C-3 and position C-7 have been synthesized. Structure of the analogues was confirmed by different techniques including IR, HNMR and mass spectroscopy. The antibacterial activity of the analogues was also assessed with the parent molecule against a series of Gram-positive and Gram-negative bacteria. Among all, the synthesized derivatives 3a, 3b and 7c showed diverse antimicrobial profile possessed a better activity in comparison to the ciprofloxacin. Docking studies of synthesized molecules revealed them as good antimicrobial candidates and their docking scores prove better binding as compared to the standard CPFX.

Occurrence of Staphylococcus aureus in dairy farms and humans with reference to antimicrobial profile in Qalyobia Governorate

Occurrence of Staphylococcus aureus in dairy farms and humans with reference to antimicrobial profile in Qalyobia Governorate

Isolation of an antimicrobial racemic phenalenone derivative from a marine-derived Penicillium sp. fungus

A new phenalenone derivative, 2,4,6,9-tetrahydroxy-7-methyl-2-prenyl-1 H-phenalene-1,3(2 H)-dione (1), was isolated from the ethyl acetate extract of a marine-derived Penicillium sp. fungus that exhibited a unique antimicrobial activity profile. The planar structure of 1 was determined through a combination of 1D and 2D NMR experiments, and circular dichroism and polarimetry indicated that it was isolated as a racemic mixture of enantiomers. The antimicrobial activity of 1 was assessed against a panel of gram-positive and gram-negative bacteria and fungal strains, and it was found to selectively inhibit the growth of Staphylococcus aureus and Mycobacterium tuberculosis.

Cesin, a short natural variant of nisin, displays potent antimicrobial activity against major pathogens despite lacking two C-terminal macrocycles.

Nisin is a widely used lantibiotic owing to its potent antimicrobial activity and its food-grade status. Its mode of action includes cell wall synthesis inhibition and pore formation, which are attributed to the lipid II binding and pore-forming domains, respectively. We discovered cesin, a short natural variant of nisin, produced by the psychrophilic anaerobe Clostridium estertheticum. Unlike other natural nisin variants, cesin lacks the two terminal macrocycles constituting the pore-forming domain. The current study aimed at heterologous expression and characterization of the antimicrobial activity and physicochemical properties of cesin. Following the successful heterologous expression of cesin in Lactococcus lactis, the lantibiotic demonstrated a broad and potent antimicrobial profile comparable to that of nisin. Determination of its mode of action using lipid II and lipoteichoic acid binding assays linked the potent antimicrobial activity to lipid II binding and electrostatic interactions with teichoic acids. Fluorescence microscopy showed that cesin lacks pore-forming ability in its natural form. Stability tests have shown the lantibiotic is highly stable at different pH values and temperature conditions, but that it can be degraded by trypsin. However, a bioengineered analog, cesin R15G, overcame the trypsin degradation, while keeping full antimicrobial activity. This study shows that cesin is a novel (small) nisin variant that efficiently kills target bacteria by inhibiting cell wall synthesis without pore formation. IMPORTANCE The current increase in antibiotic-resistant pathogens necessitates the discovery and application of novel antimicrobials. In this regard, we recently discovered cesin, which is a short natural variant of nisin produced by the psychrophilic Clostridium estertheticum. However, its suitability as an antimicrobial compound was in doubt due to its structural resemblance to nisin(1-22), a bioengineered short variant of nisin with low antimicrobial activity. Here, we show by heterologous expression, purification, and characterization that the potency of cesin is not only much higher than that of nisin(1-22), but that it is even comparable to the full-length nisin, despite lacking two C-terminal rings that are essential for nisin's activity. We show that cesin is a suitable scaffold for bioengineering to improve its applicability, such as resistance to trypsin. This study demonstrates the suitability of cesin for future application in food and/or for health as a potent and stable antimicrobial compound.

Whole genome sequence-based characterization of virulence and antimicrobial resistance gene profiles of Staphylococcus aureus isolated from food poisoning incidents in eastern China.

Staphylococcus aureus is an opportunistic foodborne pathogen occasionally isolated from diarrhea patients. In recent years, increasing studies have reported the detection of S. aureus in food poisoning incidents due to food contamination in the North and South of China. However, the epidemiology and genetic characteristics of S. aureus from food poisoning incidents in Eastern China remain unknown. The present study examined the genetic characteristics, antimicrobial resistance, and virulent factors of multidrug-resistant S. aureus isolated from 22 food poisoning incidents reported by the hospitals and health centers in Eastern China from 2011 to 2021. A total of 117 resistant and enterotoxigenic S. aureus isolates were collected and sequenced, among which 20 isolates were identified as methicillin resistant. Genetic analysis revealed 19 distinct CC/ST types, with CC6, CC22, CC59, CC88, and CC398 being the most frequent variants in methicillin-resistant S. aureus (MRSA). A considerable shift in CC types from CC1 to CC398 between 2011 and 2021 was observed in this study, indicating that CC398 may be the main epidemic strain circulating in the current food poisoning incidents. Additionally, genes for enterotoxins were detected in 55 isolates, with a prevalence of 27.8% (27/97) for methicillin-sensitive variants and 35.0% (7/20) for MRSA. The scn gene was detected in 59.0% of the isolates, demonstrating diverse contaminations of S. aureus among livestock-to-human transmission. Of the 117 isolates, only ten isolates displayed multi-drug resistance (MDR) to penicillin, tetracycline, and macrolides. None of the 117 foodborne S. aureus isolates tested positive for vanA in this study. Together, the present study provided phylogenetic characteristics of S. aureus from food poisoning incidents that emerged in Eastern China from 2011 to 2021. Our results suggested that these diarrhea episodes were hypotonic and merely transient low-MDR infections, however, further research for continued surveillance given the detection of virulence and antimicrobial resistance determinants is required to elucidate the genomic characteristics of pathogenic S. aureus in food poisoning incidents in the context of public health.