Deciphering the dynamics of methicillin-resistant Staphylococcus aureus biofilm formation: from molecular signaling to nanotherapeutic advances.

Methicillin-resistant Staphylococcus aureus (MRSA) represents a global threat, necessitating the development of effective solutions to combat this emerging superbug. In response to selective pressures within healthcare, community, and livestock settings, MRSA has evolved increased biofilm formation as a multifaceted virulence and defensive mechanism, enabling the bacterium to thrive in harsh conditions. This review discusses the molecular mechanisms contributing to biofilm formation across its developmental stages, hence representing a step forward in developing promising strategies for impeding or eradicating biofilms. During staphylococcal biofilm development, cell wall-anchored proteins attach bacterial cells to biotic or abiotic surfaces; extracellular polymeric substances build scaffolds for biofilm formation; the cidABC operon controls cell lysis within the biofilm, and proteases facilitate dispersal. Beside the three main sequential stages of biofilm formation (attachment, maturation, and dispersal), this review unveils two unique developmental stages in the biofilm formation process for MRSA; multiplication and exodus. We also highlighted the quorum sensing as a cell-to-cell communication process, allowing distant bacterial cells to adapt to the conditions surrounding the bacterial biofilm. In S. aureus, the quorum sensing process is mediated by autoinducing peptides (AIPs) as signaling molecules, with the accessory gene regulator system playing a pivotal role in orchestrating the production of AIPs and various virulence factors. Several quorum inhibitors showed promising anti-virulence and antibiofilm effects that vary in type and function according to the targeted molecule. Disrupting the biofilm architecture and eradicating sessile bacterial cells are crucial steps to prevent colonization on other surfaces or organs. In this context, nanoparticles emerge as efficient carriers for delivering antimicrobial and antibiofilm agents throughout the biofilm architecture. Although metal-based nanoparticles have been previously used in combatting biofilms, its non-degradability and toxicity within the human body presents a real challenge. Therefore, organic nanoparticles in conjunction with quorum inhibitors have been proposed as a promising strategy against biofilms. As nanotherapeutics continue to gain recognition as an antibiofilm strategy, the development of more antibiofilm nanotherapeutics could offer a promising solution to combat biofilm-mediated resistance.

Genomic dynamics of high-risk carbapenem-resistant klebsiella pneumoniae clones carrying hypervirulence determinants in Egyptian clinical settings.

BACKGROUND: Ongoing studies have revealed the global prevalence of severe infections caused by the hypervirulent strains of Klebsiella pneumoniae (K. pneumoniae). Meanwhile, the World Health Organization and the Centers for Disease Control declared carbapenem-resistant K. pneumoniae as an urgent public health threat, requiring swift and effective action to mitigate its spread. Low- and middle-income countries are severely impacted by such devastating infectious diseases owing to the ill implementation of antimicrobial practices and infection control policies. Having both hypervirulence and carbapenemase gene determinants, the emergence of convergent hypervirulent carbapenem-resistant K. pneumoniae is now being reported worldwide. METHODS: In this study, we sequenced 19 carbapenemase-producing K. pneumoniae strains recovered from various clinical specimens. Additionally, we evaluated the phenotypic antimicrobial susceptibility to multiple antimicrobial classes using the VITEK2 automated system. Utilizing the sequencing data, we characterized the sequence types, serotypes, pangenome, resistance profiles, virulence profiles, and mobile genetic elements of the examined isolates. We highlighted the emergence of high-risk clones carrying hypervirulence genetic determinants among the screened isolates. RESULTS: Our findings revealed that all carbapenem-resistant isolates exhibited either extensive- or pan-drug resistance and harbored multiple variants of resistance genes spanning nearly all the antimicrobial classes. The most prevalent carbapenemase genes detected within the isolates were blaNDM-5 and blaOXA-48. We identified high-risk clones, such as ST383-K30, ST147-K64, ST11-K15, and ST14-K2, which may have evolved into putative convergent strains by acquiring the full set of hypervirulence-associated genetic determinants (iucABCD, rmpA and/ or rmpA2, putative transporter peg-344). Additionally, this study identified ST709-K9 as a high-risk clone for the first time and uncovered that capsule types K15 and K9 carried hypervirulence genetic determinants. The most frequent Inc types found in these isolates were Col440I, IncHI1B, and Inc FII(K). CONCLUSION: This study highlights the emergence of high-risk, extensively carbapenem-resistant K. pneumoniae strains co-carrying hypervirulence determinants in Egyptian clinical settings. This poses an imminent threat not only to Egypt but also to the global community, underscoring the urgent need for enhanced surveillance and control strategies to combat this pathogen.

Recombination-mediated dissemination of Methicillin-resistant S. aureus clonal complex 1 in the Egyptian health care settings.

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) is a rapidly evolving pathogen that is frequently associated with outbreaks and sustained epidemics. This study investigated the population structure, resistome, virulome, and the correlation between antimicrobial resistance determinants with phenotypic resistance profiles of 36 representative hospital-acquired MRSA isolates recovered from hospital settings in Egypt. RESULTS: The community-acquired MRSA lineage, clonal complex 1 (CC1) was the most frequently detected clone, followed by three other globally disseminated clones, CC121, CC8, and CC22. Most isolates carried SCCmec type V and more than half of isolates demonstrated multi-drug resistant phenotypes. Resistance to linezolid, a last resort antibiotic for treating multidrug resistant MRSA, was observed in 11.11% of the isolates belonging to different genetic backgrounds. Virulome analysis indicated that most isolates harboured a large pool of virulence factors and toxins. Genes encoding aureolysin, gamma hemolysins, and serine proteases were the most frequently detected virulence encoding genes. CC1 was observed to have a high pool of AMR resistance determinants including cfr, qacA, and qacB genes, which are involved in linezolid and quaternary ammonium compounds resistance, as well as high content of virulence-related genes, including both of the PVL toxin genes. Molecular clock analysis revealed that CC1 had the greatest frequency of recombination (compared to mutation) among the four major clones, supporting the role of horizontal gene transfer in modulating AMR and hypervirulence in this clone. CONCLUSIONS: This pilot study provided evidence on the dissemination success of CA-MRSA clone CC1 among Egyptian hospitals. Co-detection of multiple AMR and virulence genes in this lineage pose a broad public health risk, with implications for successful treatment. The results of this study, together with other surveillance studies in Egypt, should be used to develop strategies for controlling MRSA infections in Egyptian health-care settings.

Stress resistance associated with multi-host transmission and enhanced biofilm formation at 42 °C among hyper-aerotolerant generalist Campylobacter jejuni.

One of the emerging conundrums of Campylobacter food-borne illness is the bacterial ability to survive stressful environmental conditions. We evaluated the heterogeneity among 90 C. jejuni and 21 C. coli isolates from different sources in Egypt with respect to biofilm formation capabilities (under microaerobic and aerobic atmosphere) and resistance to a range of stressors encountered along the food chain (aerobic stress, refrigeration, freeze-thaw, heat, peracetic acid, and osmotic stress). High prevalence (63%) of hyper-aerotolerant (HAT) isolates was observed, exhibiting also a significantly high tolerance to heat, osmotic stress, refrigeration, and freeze-thaw stress, coupled with high biofilm formation ability which was clearly enhanced under aerobic conditions, suggesting a potential link between stress adaptation and biofilm formation. Most HAT multi-stress resistant and strong biofilm producing C. jejuni isolates belonged to host generalist clonal complexes (ST-21, ST-45, ST-48 and ST-206). These findings highlight the potential role of oxidative stress response systems in providing cross-protection (resistance to other multiple stress conditions) and enhancing biofilm formation in Campylobacter and suggest that selective pressures encountered in hostile environments have shaped the epidemiology of C. jejuni in Egypt by selecting the transmission of highly adapted isolates, thus promoting the colonization of multiple host species by important disease-causing lineages.

Evaluation of antioxidant and anti-inflammatory efficacy of caffeine in rat model of neurotoxicity.

Objective: The present study aims to investigate the neuroprotective effect of caffeine against aluminum chloride (AlCl3)-induced neurotoxicity in rats. Methods: Twenty-one male albino rats were divided into 3 groups: control, AlCl3-intoxicated group that received daily oral administration of AlCl3 (100 mg/kg for 30 days) and protected group injected daily with caffeine (20 mg/kg intraperitoneally) one hour before oral administration of AlCl3 for 30 days. Levels of lipid peroxidation, reduced glutathione, and nitric oxide and the activities of acetylcholinesterase (AchE) and Na+/K+-ATPase were measured spectrophotometrically. Tumor necrosis factor-α (TNF-α) was evaluated by ELISA kit. Results: The data revealed evidence of oxidative and nitrosative stress in the cerebral cortex, hippocampus, and striatum of AlCl3-intoxicated rats. This was indicated from the increased levels of lipid peroxidation and nitric oxide together with the decreased level of reduced glutathione. Moreover, the daily AlCl3 administration increased AchE and Na+/K+-ATPase activities and the level of TNF-α in the selected brain regions. Protection with caffeine ameliorated the oxidative stress induced by AlCl3 in the cerebral cortex, hippocampus, and striatum. In addition, caffeine restored the elevated level of TNF-α in the hippocampus and striatum. This was accompanied by an improvement in the activities of AchE and Na+/K+-ATPase in the studied brain regions. Discussion and conclusions: The present findings clearly indicate that caffeine provides a significant neuroprotection against AlCl3-induced neurotoxicity mediated by its antioxidant, anti-inflammatory, and anticholinesterase properties.

The first molecular detection of Clostridium perfringens from pneumonic cases associated with foot and mouth disease in cattle and buffalo in Egypt.

Panting syndrome and respiratory infection have been recorded in complicated cases of foot and mouth disease (FMD) in cattle. However, investigations on the causative agents of respiratory disease in such cases are scarce. In this study, 30 animals (13 buffalo and 17 cattle) suffering from respiratory distress associated with signs of FMD were examined. Serum samples were collected and FMD infection was confirmed. Bacteriological examination of lungs from eight necropitized cases revealed the presence of C. perfringens. Multiplex polymerase chain reaction (mPCR) was performed on the positive samples followed by sequencing analysis. The alpha toxin gene (plc) of C. perfringens was identified in six cases. The present investigation highlights the role of clostridial infection as a complication of FMD in cattle and buffalo. This is the first report identifying the C. perfringens toxins from lung of animals with respiratory distress associated with FMD infection.

Antimicrobial resistance and virulence characterization of Staphylococcus aureus and coagulase-negative staphylococci from imported beef meat.

BACKGROUND: The objectives of this study were to characterize the diversity and magnitude of antimicrobial resistance among Staphylococcus species recovered from imported beef meat sold in the Egyptian market and the potential mechanisms underlying the antimicrobial resistance phenotypes including harboring of resistance genes (mecA, cfr, gyrA, gyrB, and grlA) and biofilm formation. RESULTS: The resistance gene mecA was detected in 50% of methicillin-resistant non-Staphylococcus aureus isolates (4/8). Interestingly, our results showed that: (i) resistance genes mecA, gyrA, gyrB, grlA, and cfr were absent in Staphylococcus hominis and Staphylococcus hemolyticus isolates, although S. hominis was phenotypically resistant to methicillin (MR-non-S. aureus) while S. hemolyticus was resistant to vancomycin only; (ii) S. aureus isolates did not carry the mecA gene (100%) and were phenotypically characterized as methicillin- susceptible S. aureus (MSS); and (iii) the resistance gene mecA was present in one isolate (1/3) of Staphylococcus lugdunensis that was phenotypically characterized as methicillin-susceptible non-S. aureus (MSNSA). CONCLUSIONS: Our findings highlight the potential risk for consumers, in the absence of actionable risk management information systems, of imported foods and advice a strict implementation of international standards by different venues such as CODEX to avoid the increase in prevalence of coagulase positive and coagulase negative Staphylococcus isolates and their antibiotic resistance genes in imported beef meat at the Egyptian market.

Saprolegniosis in Nile Tilapia: Identification, Molecular Characterization, and Phylogenetic Analysis of Two Novel Pathogenic Saprolegnia Strains.

Saprolegniosis is a fungal infection that leads to huge economic losses in tilapia aquaculture. Saprolegnia spp. are usually implicated as the etiological agents, but their identification is sometimes troublesome and confusing. In this study, two Saprolegnia strains (ManS22 and ManS33) were isolated from Nile Tilapia Oreochromis niloticus suffering from saprolegniosis. Both isolates were characterized morphologically and from internal transcribed spacer (ITS) sequence data. Additionally, both strains were tested for pathogenicity, and they were highly pathogenic and caused cumulative mortalities of 88.9% and 95.6%, respectively. Initially, the two strains were identified, by morphology of sexual and asexual stages, as members of the genus Saprolegnia. For more definitive identification and characterization, the ITS region of the ribosomal RNA genes was amplified and sequenced, and sequences were compared with other known sequences in GenBank. A phylogenetic tree constructed using the neighbor-joining method revealed that the two strains fell into two clusters within the species Saprolegnia parasitica. Cluster 1 included the ManS33 strain and cluster 2 the ManS22 strain. Cluster 1 grouped the ManS33 strain with other S. parasitica stains and shared 97-99% sequence similarity. Cluster 2 contained only the ManS22 strain and shared 93-94% similarity to several reference sequences of S. parasitica strains. Therefore, our findings suggest that ManS22 represents a newly described strain of S. parasitica. Received April 19, 2016; accepted October 27, 2016.

Genetic elements associated with antimicrobial resistance among avian pathogenic Escherichia coli.

BACKGROUND: Avian-pathogenic Escherichia coli (APEC) are pathogenic strains of E. coli that are responsible for one of the most predominant bacterial disease affecting poultry worldwide called avian colibacillosis. This study describes the genetic determinants implicated in antimicrobial resistance among APEC isolated from different broiler farms in Egypt. METHODS: A total of 116 APEC were investigated by serotyping, antimicrobial resistance patterns to 10 antimicrobials, and the genetic mechanisms underlying the antimicrobial-resistant phenotypes. RESULTS: Antibiogram results showed that the highest resistance was observed for ampicillin, tetracycline, nalidixic acid, and chloramphenicol. The detected carriage rate of integron was 29.3% (34/116). Further characterization of gene cassettes revealed the presence gene cassettes encoding resistance to trimethoprim (dfrA1, dfrA5, dfrA7, dfrA12), streptomycin/spectinomycin (aadA1, aadA2, aadA5, aadA23), and streptothricin (sat2). To our knowledge, this the first description of the presence of aadA23 in APEC isolates. Analysis of other antimicrobial resistance types not associated with integrons revealed the predominance of resistance genes encoding resistance to tetracycline (tetA and tetB), ampicillin (bla TEM), chloramphenicol (cat1), kanamycin (aphA1), and sulphonamide (sul1 and sul2). Among ciprofloxacin-resistant isolates, the S83L mutation was the most frequently substitution observed in the quinolone resistance-determining region of gyrA (56.3%). The bla TEM and bla CTX-M-1 genes were the most prevalent among APEC isolates producing extended-spectrum beta-lactamase (ESßL). CONCLUSIONS: These findings provided important clues about the role of integron-mediated resistance genes together with other independent resistance genes and chromosomal mutations in shaping the epidemiology of antimicrobial resistance in E. coli isolates from poultry farms in Egypt.

Prevalence, Molecular Characterization, and Antimicrobial Susceptibility of Methicillin-Resistant Staphylococcus aureus Isolated from Milk and Dairy Products.

The present work was undertaken to study the prevalence, molecular characterization, virulence factors, and antimicrobial susceptibility of methicillin-resistant Staphylococcus aureus (MRSA) in raw milk and dairy products in Mansoura City, Egypt. MRSA was detected in 53% (106/200) among all milk and dairy products with prevalence rates of 75%, 65%, 40%, 50%, and 35% in raw milk, Damietta cheese, Kareish cheese, ice cream, and yogurt samples, respectively. The mean S. aureus counts were 3.49, 3.71, 2.93, 3.40, and 3.23 log10 colony-forming units (CFU)/g among tested raw milk, Damietta cheese, Kareish cheese, ice cream and yogurt, respectively, with an overall count of 3.41 log10 CFU/g. Interestingly, all recovered S. aureus isolates were genetically verified as MRSA strains by molecular detection of the mecA gene. Furthermore, genes encoding α-hemolysin (hla) and staphylococcal enterotoxins (sea, seb, sec) were detected in all isolates. The antimicrobial susceptibility pattern of recovered MRSA isolates against 13 tested antimicrobials revealed that the least effective drugs were penicillin G, cloxacillin, tetracycline, and amoxicillin with bacterial resistance percentages of 87.9%, 75.9%, 65.2%, and 55.6%, respectively. These findings suggested that milk and dairy products represent a potential infection risk threat of multidrug-resistant and toxigenic S. aureus in Egypt due to neglected hygienic practices during production, retail, or storage stages. These findings highlighted the crucial importance of applying more restrictive hygienic measures in dairy production in Egypt for food safety.

Genetic diversity of Shiga toxin-producing Escherichia coli O157 : H7 recovered from human and food sources.

The aim of this study was to identify an epidemiological association between Shiga toxin-producing Escherichia coli O157 : H7 strains associated with human infection and with food sources. Frequency distributions of different genetic markers of E. coli O157 : H7 strains recovered from human and food sources were compared using molecular assays to identify E. coli O157 : H7 genotypes associated with variation in pathogenic potential and host specificity. Genotypic characterization included: lineage-specific polymorphism assay (LSPA-6), clade typing, tir (A255T) polymorphism, Shiga toxin-encoding bacteriophage insertion site analysis and variant analysis of Shiga toxin 2 gene (stx2a and stx2c) and antiterminator Q genes (Q933 and Q21). The intermediate lineage (LI/II) dominated among both food and human strains. Compared to other clades, clades 7 and 8 were more frequent among food and human strains, respectively. The tir (255T) polymorphism occurred more frequently among human strains than food strains. Q21 and Q933 + Q21 were found at significantly higher frequencies among food and human strains, respectively. Moreover, stx2a and stx2a+c were detected at significantly higher frequencies among human strains compared to food strains. Bivariate analysis revealed significant concordance (P<0.05) between the LSPA-6 assay and the other typing methods. Multivariable regression analysis suggested that tir (255T) was the most distinctive genotype that can be used to detect bacterial clones with potential risk for human illness from food sources. This study supported previous reports of the existence of diversity in genetic markers among different isolation sources by including E. coli O157 : H7 strains from both food and human sources. This might enable tracking genotypes with potential risk for human illness from food sources.

Interaction of different Shiga toxin-producing Escherichia coli serotypes with Caco-2 cells.

Shiga toxin-producing Escherichia coli (STEC) is defined by the ability to produce one or more types of Shiga toxins. In an attempt to better understand the mechanisms that underlie pathogenicity among STEC foodborne infection, we compared different STEC serotypes recovered from food sources (O26:H11, O103:H2, and O157:H7) for their interaction with human intestinal epithelial cells using the Caco-2 cell line as an infection model. Bacterial uptake was determined using gentamicin protection assay and results were confirmed by fluorescent microscopy. Our results revealed no significant difference in adherence among tested serotypes. Nonetheless, E. coli O157:H7 exhibited a significant increase of internalization ability and survived significantly better over different time points for up to 24 h. To study cellular invasion mechanisms, multiple inhibitors with known effects on eukaryotic cell structures and processes were used. Inhibition of bacterial and host cell protein synthesis significantly diminished entry in all tested serotypes, suggesting that invasion is an active process that requires both bacterial and eukaryotic protein syntheses. Cytochalasin D (an actin microfilament inhibitor) and staurosporine (inhibitor of several protein kinases) significantly decreased internalization of all tested serotypes. Our results suggested that invasion by STEC varies between different serotypes, might correlate with clinical outcome, and is receptor mediated. This process is dependent on microfilament-dependent pathway and phosphorylation of cell proteins but not on formation of microtubules.

Carbapenem and colistin-resistant hypervirulent Klebsiella pneumoniae: An emerging threat transcending the egyptian food chain.

BACKGROUND: Carbapenem-resistant Klebsiella pneumoniae (CRKP) is a great public health problem and is associated with many disease outbreaks and high mortality rates. Alarmingly, K. pneumoniae has been isolated from food in several recent studies. This study aimed to investigate the prevalence and characteristics of CRKP in food samples from Egypt. METHODS: A total of 311 food samples (including 116 minced meat, 92 chicken meat, 75 diced meat, and 28 mutton) were collected from local markets in Egypt and were screened for CRKP with the determination of their antimicrobial resistance profiles. The whole genome sequence was done for 23 CRKP isolates to clarify the relationship between CRKP from food and human cases in Egypt using the SNP core genome. The conjugation probability of the blaNDM-5 harboring plasmid was identified using oriTfinder RESULTS: CRKP was isolated from 11% (35/311) of the samples, with 45.71% (16/35) of them showing resistance to colistin, one of the last-resort options for treating CRKP-mediated infections. In addition to the carbapenem and colistin resistance, the CRKP isolates frequently exhibited resistance to multiple antimicrobials including ß-lactams, fluoroquinolones, aminoglycosides, tetracyclines, and chloramphenicol. In addition, most of the CRKP were potentially hypervirulent K. pneumoniae (HvKP) identified as phylogroup Kp1 and of high-risk groups as detected in STs reported in many human outbreaks globally, such as ST383 and ST147. The core-genome phylogeny showed similarities between the isolates from this study and those previously isolated from clinical human samples in Egypt. In addition, analysis of the plasmid on which blaNDM is encoded revealed that several antimicrobial resistance genes such as blaOXA-9, blaCTX-M-15, aac(6')-Ib, qnrS1, and several virulence genes are encoded on the same plasmid. CONCLUSIONS: This study is significant for food safety and public health and is important to further identify the change in the epidemiology of CRKP infections, especially the consumption of contaminated food products.

Unveiling the microevolution of antimicrobial resistance in selected Pseudomonas aeruginosa isolates from Egyptian healthcare settings: A genomic approach.

The incidence of Pseudomonas aeruginosa infections in healthcare environments, particularly in low-and middle-income countries, is on the rise. The purpose of this study was to provide comprehensive genomic insights into thirteen P. aeruginosa isolates obtained from Egyptian healthcare settings. Phenotypic analysis of the antimicrobial resistance profile and biofilm formation were performed using minimum inhibitory concentration and microtiter plate assay, respectively. Whole genome sequencing was employed to identify sequence typing, resistome, virulome, and mobile genetic elements. Our findings indicate that 92.3% of the isolates were classified as extensively drug-resistant, with 53.85% of these demonstrating strong biofilm production capabilities. The predominant clone observed in the study was ST773, followed by ST235, both of which were associated with the O11 serotype. Core genome multi-locus sequence typing comparison of these clones with global isolates suggested their potential global expansion and adaptation. A significant portion of the isolates harbored Col plasmids and various MGEs, all of which were linked to antimicrobial resistance genes. Single nucleotide polymorphisms in different genes were associated with the development of antimicrobial resistance in these isolates. In conclusion, this pilot study underscores the prevalence of extensively drug-resistant P. aeruginosa isolates and emphasizes the role of horizontal gene transfer facilitated by a diverse array of mobile genetic elements within various clones. Furthermore, specific insertion sequences and mutations were found to be associated with antibiotic resistance.

Various investigations of ameliorative role of Ashwagandha seeds (Withania somnifera) against amoxicillin toxicity.

Several studies showed the adverse effects of amoxicillin on various body organs. So, this research has been designed to evaluate the modulatory role of Ashwagandha seed extract (ASE) against amoxicillin (AM) toxicity. Rats treated with AM (90 mg/kg), protected by ASE doses (100, 200 and 300 mg/kg), and treated by ASE at the same three doses. At the end of the experimental period, DNA comet assay, cytogenetic examinations, sperm-shape analysis, evaluation of the malondialdehyde (MDA) percentages, histopathological examinations, and biophysical tests (modulus, relaxation time, permittivity, entropy, and internal energy change of brain) were documented. The results confirmed that AM treatment induced significant elevation of DNA damage, cytogenetic aberrations, and MDA content in brain, liver, and testis tissues and sperm-shape anomalies. ASE treatment significantly minimized the genetic changes, sperm-shape anomalies, and MDA generation. These enhancements were more pronounced by protective ASE and increased by increasing the dose level. In histopathological examinations, AM treatment caused neurotoxicity in brain tissue. ASE treatment, partially, minimized these damages and the positive effects of therapeutic ASE were more noticeable. Biophysical parameters showed that therapeutic ASE was better for relaxation time, permittivity, and free energy change. Protective and therapeutic ASE were able to recover entropy and internal energy changes in variant degrees.

Emergence of carbapenem resistant gram-negative pathogens with high rate of colistin resistance in Egypt: A cross sectional study to assess resistance trends during the COVID-19 pandemic.

The current study investigated the temporal phenotypic and genotypic antimicrobial resistance (AMR) trends among multi-drug resistant and carbapenem-resistant Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa recovered from Egyptian clinical settings between 2020 and 2021. Bacterial identification and antimicrobial sensitivity of 111 clinical isolates against a panel of antibiotics were performed. Molecular screening for antibiotic resistance determinants along with integrons and associated gene cassettes was implemented. An alarming rate (98.2%) of these isolates were found to be phenotypically resistant to carbapenem. Although 23.9 % K. pneumoniae isolates were phenotypically resistant to colistin, no mobile colistin resistance (mcr) genes were detected. Among carbapenem-resistant isolates, blaNDM and blaOXA-48-like were the most prevalent genetic determinants and were significantly overrepresented among K. pneumoniae. Furthermore, 84.78% of K. pneumoniae isolates co-produced these two carbapenemase genes. The plasmid-mediated quinolone resistance genes (qnrS and qnrB) were detected among the bacterial species and were significantly more prevalent among K. pneumoniae. Moreover, Class 1 integron was detected in 82% of the bacterial isolates. This study alarmingly reveals elevated resistance to last-resort antibiotics such as carbapenems as well as colistin which impose a considerable burden in the health care settings in Egypt. Our future work will implement high throughput sequencing-based antimicrobial resistance surveillance analysis for characterization of novel AMR determinants. This information could be applied as a step forward to establish a robust antibiotic stewardship program in Egyptian clinical settings, thereby addressing the rising challenges of AMR.

BDNF Val66Met Polymorphism: Suggested Genetic Involvement in Some Children with Learning Disorder.

Brain-derived neurotrophic factor (BDNF) plays an essential role in neuronal survival, especially in areas responsible for memory and learning. The BDNF Val66Met polymorphism has been described as a cognitive modifier in people with neuropsychiatric disorders. BDNF levels have been found to be low in children with learning disorder (LD). However, Val66Met polymorphism has not been studied before in such children. The aim was to investigate the presence of BDNF val66Met polymorphism in a group of children with specific LD and to verify its impact on their cognitive abilities. The participants in this cross-sectional study (N = 111) were divided into two groups: one for children with LD and the other for neurotypical (NT) ones. Children with LD (N = 72) were diagnosed according to the DSM-5 criteria. Their abilities were evaluated using Stanford-Binet Intelligence Scale, dyslexia assessment test, Illinois Test of Psycholinguistic Abilities, and phonological awareness test. Genotyping of BDNF Val66Met polymorphism was performed for all participants. The frequency of the Met allele was 26% among children with LD (6 children had homozygous, 26 had heterozygous genotype). The percentage of participants with deficits in reading, writing, and phonemic segmentation was higher in Met allele carriers when compared to non-Met allele carriers in LD group. The frequency of Met allele among NT children was 3.85% (0 homozygous, 3 children had heterozygous genotype) (p = 0.00001). The high frequency of Val66Met polymorphism among children with LD introduces the BDNF gene as a genetic modifier of learning performance in some children who manifest specific learning disorder (developmental dyslexia).

Long-term exposure to food-grade disinfectants causes cross-resistance to antibiotics in Salmonella enterica serovar Typhimurium strains with different antibiograms and sequence types.

BACKGROUND: Disinfectants are important in the food industry to prevent the transmission of pathogens. Excessive use of disinfectants may increase the probability of bacteria experiencing long-term exposure and consequently resistance and cross-resistance to antibiotics. This study aims to investigate the cross-resistance of multidrug-resistant, drug-resistant, and drug-susceptible isolates of Salmonella enterica serovar Typhimurium (S. Typhimurium) with different sequence types (STs) to a group of antibiotics after exposure to different food-grade disinfectants. METHODS: A panel of 27 S. Typhimurium strains with different antibiograms and STs were exposed to increasing concentrations of five food-grade disinfectants, including hydrogen peroxide (H2O2), benzalkonium chloride (BAC), chlorine dioxide (ClO2), sodium hypochlorite (NaClO), and ethanol. Recovered evolved strains were analyzed using genomic tools and phenotypic tests. Genetic mutations were screened using breseq pipeline and changes in resistance to antibiotics and to the same disinfectant were determined. The relative fitness of evolved strains was also determined. RESULTS: Following exposure to disinfectants, 22 out of 135 evolved strains increased their resistance to antibiotics from a group of 14 clinically important antibiotics. The results also showed that 9 out of 135 evolved strains had decreased resistance to some antibiotics. Genetic mutations were found in evolved strains. A total of 77.78% of ST34, 58.33% of ST19, and 66.67% of the other STs strains exhibited changes in antibiotic resistance. BAC was the disinfectant that induced the highest number of strains to cross-resistance to antibiotics. Besides, H2O2 induced the highest number of strains with decreased resistance to antibiotics. CONCLUSIONS: These findings provide a basis for understanding the effect of disinfectants on the antibiotic resistance of S. Typhimurium. This work highlights the link between long-term exposure to disinfectants and the evolution of resistance to antibiotics and provides evidence to promote the regulated use of disinfectants.

Biosynthetic gene cluster signature profiles of pathogenic Gram-negative bacteria isolated from Egyptian clinical settings.

Biosynthetic gene clusters (BGCs) are a subset of consecutive genes present within a variety of organisms to produce specialized metabolites (SMs). These SMs are becoming a cornerstone to produce multiple medications including antibacterial and anticancer agents. Natural products (NPs) also play a pivotal role in enhancing the virulence of ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.), which represent a global health threat. We aimed to sequence and computationally analyze the BGCs present in 66 strains pertaining to three different ESKAPE pathogenic species: 21 A. baumannii, 28 K. pneumoniae, and 17 P. aeruginosa strains recovered from clinical settings in Egypt. DNA was extracted using QIAamp DNA Mini kit and Illumina NextSeq 550 was used for whole-genome sequencing. The sequences were quality-filtered by fastp and assembled by Unicycler. BGCs were detected by antiSMASH, BAGEL, GECCO, and PRISM, and aligned using Clinker. The highest abundance of BGCs was detected in P. aeruginosa (590), then K. pneumoniae (146) and the least in A. baumannii strains (133). P. aeruginosa isolates shared mostly the non-ribosomal peptide synthase (NRPS) type, K. pneumoniae isolates shared the ribosomally synthesized and post-translationally modified peptide-like (RiPP-like) type, while A. baumannii isolates shared the siderophore type. Most of the isolates harbored non-ribosomal peptide (NRP) BGCs with few K. pneumoniae isolates encoding polyketide BGCs. Sactipeptides and bottromycin BGCs were the most frequently detected RiPP clusters. We hypothesize that each species' BGC signature confers its virulence. Future experiments will link the detected clusters with their species and determine whether the encoded SMs are produced and cause their virulence. IMPORTANCE Our study analyzes the biosynthetic gene clusters (BGCs) present in 66 assemblies from clinical ESKAPE pathogen isolates pertaining to Acinetobacter baumannii, Klebsiella pneumoniae, and Pseudomonas aeruginosa strains. We report their sequencing and assembly followed by the analysis of their BGCs using several bioinformatics tools. We then focused on the most abundant BGC type in each species and we discussed their potential roles in the virulence of each species. This study is pivotal to further build on its experimental work that deciphers the role in virulence, possible antibacterial effects, and characterization of the encoded specialized metabolites (SMs). The study highlights the importance of studying the "harmful" BGCs and understanding the pathogenicity and virulence of those species, as well as possible benefits if the SMs were used as antibacterial agents. This could be the first study of its kind from Egypt and would shed light on BGCs from ESKAPE pathogens from Egypt.

Benzalkonium chloride forces selective evolution of resistance towards antibiotics in Salmonella enterica serovar Typhimurium.

BACKGROUND: Although food-grade disinfectants are extensively used worldwide, it has been reported that the long-term exposure of bacteria to these compounds may represent a selective force inducing evolution including the emergence of antibiotic resistance. However, the mechanism underlying this correlation has not been elucidated. This study aims to investigate the genomic evolution caused by long-term disinfectant exposure in terms of antibiotic resistance in Salmonella enterica Typhimurium. METHODS: S. Typhimurium isolates were exposed to increasing concentrations of benzalkonium chloride (BAC) and variations of their antibiotic susceptibilities were monitored. Strains that survived BAC exposure were analyzed at whole genome perspective using comparative genomics, and Sanger sequencing-confirmed mutations in ramR gene were identified. Next, the efflux activity in ramR-mutated strains shown as bisbenzimide accumulation and expression of genes involved in AcrAB-TolC efflux pump using quantitative reverse transcriptase PCR were determined. RESULTS: Mutation rates of evolved strains varied from 5.82 × 10-9 to 5.56 × 10-8, with fold increase from 18.55 to 1.20 when compared with strains evolved without BAC. Mutations in ramR gene were found in evolved strains. Upregulated expression and increased activity of AcrAB-TolC was observed in evolved strains, which may contribute to their increased resistance to clinically relevant antibiotics. In addition, several indels and point mutations in ramR were identified, including L158P, A37V, G42E, F45L, and R46H which have not yet been linked to antimicrobial resistance. Resistance and mutations were stable after seven consecutive cultivations without BAC exposure. These results suggest that strains with sequence type (ST) ST34 were the most prone to mutations in ramR among the three STs tested (ST34, ST19, ST36). CONCLUSIONS: This work demonstrated that disinfectants, specifically BAC forces S. Typhimurium to enter a specific evolutionary trajectory towards antibiotic resistance illustrating the side effects of long-term exposure to BAC and probably also to other disinfectants. Most significantly, this study provides new insights in understanding the emergence of antibiotic resistance in modern society.