Vancomycin-resistant S. Aureus Research Articles

Bacteriological Profile and Antibiotics used for Septic Patients in Karbala, Iraq

Background: Sepsis is an issue of globular health care, characterized by complete inflammation of the body in response to microbial infection, which results in organ malfunction. This becomes a chronic patient complication. Therefore, sepsis may be a diverse and combined disease with varying etiology, severity, and treatment plan. Objectives: The purpose of this study was to demonstrate the existence of exposure and the resistance of microorganisms to the range of antibiotics in subjects of the local community. Results: Among 11 species of bacteria isolated from a variety of specimens, Escherichia coli (22.1%) and Staphylococcus aureus (20.3%) were the most common organism found over the subjects had been collected. The most sensitive antibiotics for Gram-negative E. coli were colistin 97%, imipenem 89%, meropenem 88%, and amikacin 79%, while the highest resistant rate was benzylpenicillin 93%, and oxacillin 86%. Methicillin-resistant S. aureus (MRSA) prevalence was 90%, vancomycin-resistant S. aureus (VRSA) 31%. Conclusion: Because of the high incidence of VRSA and MRSA, clinicians should become more vigilant in using vancomycin and another important antibiotic. Moreover, maintain this useful drug to be used for a prolonged time with good efficacy.

Repurposing Kinase Inhibitor Bay 11-7085 to Combat Staphylococcus aureus and Candida albicans Biofilms.

Staphylococcus aureus and Candida spp. are commonly linked with topical biofilm-associated infections such as those found on chronic wounds. These biofilms are notoriously difficult to treat, highlighting the grave need to discover and study new broad-spectrum agents to combat associated infections. Here we report that the kinase inhibitor Bay 11-7085 exhibited bactericidal activity against multidrug-resistant S. aureus with a minimum inhibitory concentration (MIC) of 4 μg/ml. In addition, S. aureus strain MW2 did not acquire resistance to antibiotic pressure. Furthermore, Bay 11-7085 exhibited potency against Candida albicans and the emerging pathogen Candida auris with a MIC of 0.5–1 μg/ml. Bay 11-7085 partially inhibited and eradicated biofilm formation of various pathogens, such as VRSA (vancomycin-resistant S. aureus), as well as antifungal-resistant Candida spp. isolates. Notably, Bay 11-7085 partially inhibited initial cell attachment and formation of a VRSA-C. albicans polymicrobial biofilm in vitro. In contrast to C. albicans, inhibition of VRSA biofilm was linked to initial cell attachment independent of its bactericidal activity. Finally, Bay 11-7085 was effective in vivo at increasing the lifespan of C. elegans during an S. aureus and a C. albicans infection. Our work proposes kinase inhibitor Bay 11-7085 as a potential compound capable of combating biofilms associated with primary multidrug-resistant bacteria and yeast pathogens associated with wound infections.

Effect of silver nanoparticles on vancomycin resistant Staphylococcus aureus infection in critically ill patients

ABSTRACT A prevalent increase in antimicrobial resistance represents a universal obstacle for the treatment of Staphylococcus aureus (S. aureus) infection, especially in critically ill patients. Silver nanoparticles are defined as broad spectrum bactericidal agents, which might be effective against vancomycin resistant S. aureus (VRSA). In this study, we examined the bactericidal efficacy of silver nanoparticles on VRSA in 150 blood and sputum samples isolated from intensive care patients. Methicillin resistant S. aureus (MRSA) isolates were identified in 83 samples, with an incidence of 55.3%. Meanwhile, VRSA isolates were found in 11 and 8 isolates (a total of 19 isolates out of 150) from sputum and blood samples, with an incidence of 14.67% and 10.67%, respectively, with a total incidence of 12.67%. Vancomycin intermediate S. aureus (VISA) isolates had an inhibitory zone ranging from 9 to 13 mm, which was found in 13 out of 19 isolates, whereas VRSA isolates had an inhibitory zone ranging from 0 to 6 mm, which was detected in 6 out of 19 isolates. The findings of this study confirm that silver nanoparticles are an effective treatment against VRSA.

Multidrug-, methicillin-, and vancomycin-resistant Staphylococcus aureus isolated from ready-to-eat meat sandwiches: An ongoing food and public health concern

Methicillin-resistant S. aureus (MRSA) and their antimicrobial resistance pose exacerbating global health threats and endangering everyone. Thus, the prevalence, molecular characterization of virulence genes, and antimicrobial resistance patterns of strains isolated from 225 beef burger and hot dog sandwiches vended in Mansoura city, Egypt were determined. 83.1% of the sandwiches tested were contaminated with coagulase-positive S. aureus, with a mean count of 4 × 103 CFU/g. Genes encoding mecA, α-hemolysin, staphylococcal enterotoxins, and toxic shock syndrome toxin-1 were detected in 22.6%, 96.3%, 61.1%, and 0% of the strains isolated, respectively. Of the 190 coagulase-positive strains, 43 (22.6%) were confirmed as MRSA. Among them, 4 strains (2.1%) were vancomycin-resistant S. aureus (VRSA) and resistant to all antimicrobials tested. Interestingly, all isolates were resistant to at least one of the antimicrobials tested, with 75.2% being multi-drug resistant (MDR) and an average multiple antimicrobial resistance (MAR) index of 0.503. Not less important, 100%, 96.3%, 90.5%, 79.5%, 73.7%, 62.6%, and 48.9% of isolates were resistant to Kanamycin, Nalidixic acid, Cefotaxime, Sulphamethoxazole-Trimethoprim, Penicillin G, Tetracycline, and Cephalothin, respectively. The potential hazard of MDR-, MRSA-, and VRSA-contaminated sandwiches may be an indication of the presence of what is more dangerous. Hence, strict hygienic measures and good standards of food handler's personal hygiene to prevent transmission of these pathogens to consumers are imperative.

Prevalence, Antimicrobial Resistance, and Molecular Characterization of Staphylococcus aureus Isolated from Animals, Meats, and Market Environments in Xinjiang, China.

Staphylococcus aureus has been recognized as an important foodborne pathogen. However, knowledge about the epidemiology and genetic characteristics of S. aureus in the meat production chain from farm to market is limited. The aim of this study was to investigate the genetic characteristics of S. aureus in animal samples isolated from Xinjiang province farms and farmer' markets, by determining staphylococcal protein A (spa) repeat region and virulence factor typing, and by assessment of antimicrobial resistance. Out of 1324 samples, 128 (9.7%) were positive for S. aureus, 26 (2.0%) of them were identified as methicillin-resistant S. aureus (MRSA) and 88 (6.6%) of them were identified as vancomycin-resistant S. aureus (VRSA). Antimicrobial resistance was determined using the disk diffusion method. S. aureus isolates showed resistance to penicillin G (98.4%), clarithromycin (69.5%), erythromycin (69.5%), vancomycin (68.8%), and tetracycline (67.2%). A total of 80.4% of isolates showed resistance to three or more antimicrobial classes. PCR was used to detect ten virulence genes such as the enterotoxin (sea, seb, and sec), hemolysin (hla and hlb), clumping factor (clfA), and fibronectin-binding proteins A and B (fnbA and fnbB). Our study showed that isolates harbored two or seven virulence genes. All strains encode hla and clfA, and half of them encode hlb and enterotoxin genes. The spa typing results showed that the 128 isolates were grouped into 32 spa types. The main spa types were t127 (22.7%), t2592 (12.5%), t437 (10.9%), and t2616 (10.9%). Notably, isolates of t437 type accounted for 46.2% of the MRSA. Our data indicate that meats in the slaughterhouse and farmers' markets were contaminated with S. aureus. S. aureus virulence genes and spa types were diverse, and its antibiotic resistance was serious. The presence of MRSA and VRSA represents potential public health risks and warrants further investigation regarding the driving factors of such resistance and their transmission to humans.

Grapefruit Seed Extract as a Natural Derived Antibacterial Substance against Multidrug-Resistant Bacteria.

Multidrug-resistant (MDR) bacteria are increasing due to the abuse and misuse of antibiotics, and nosocomial infections by MDR bacteria are also increasing. The aim of this study was to identify new substances that can target MDR bacteria among 12 plant extracts that are known to have antibacterial effects. The experiments were performed by the disk diffusion test and microdilution minimum inhibitory concentration (MIC) test, as described by the Clinical and Laboratory Standards Institute (CLSI). By screening against methicillin-sensitive Staphylococcus aureus (MSSA), grapefruit seed extract (GSE) was selected from 12 plant extracts for subsequent experiments. GSE showed antibacterial effects against methicillin-resistant S. aureus (MRSA) and vancomycin-resistant S. aureus (VRSA) in the disk diffusion test. Even at the lowest concentration, GSE showed antibacterial activity in the microdilution MIC test. As a result, we can conclude that GSE is a naturally derived antibacterial substance that exhibits a favorable antibacterial effect even at a very low concentration, so it is a good candidate for a natural substance that can be used to prevent or reduce nosocomial infections as coating for materials used in medical contexts or by mixing a small amount with other materials.

Staphylococcus aureus resistance to albocycline can be achieved by mutations that alter cellular NAD/PH pools

Small molecule target identification is a critical step in modern antibacterial drug discovery, particularly against multi-drug resistant pathogens. Albocycline (ALB) is a macrolactone natural product with potent activity against methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant S. aureus (VRSA) whose mechanism of action has been elusive to date. Herein, we report biochemical and genomic studies that reveal ALB does not target bacterial peptidoglycan biosynthesis or the ribosome; rather, it appears to modulate NADPH ratios and upregulate redox sensing in the cell consistent with previous studies at Upjohn. Owing to the complexity inherent in biological pathways, further genomic assays are needed to identify the true molecular target(s) of albocycline.

Isolation and characterization of six gamma-irradiated bacteriophages specific for MRSA and VRSA isolated from skin infections

ABSTRACT Although skin infections are usually uncomplicated, it may indicate systemic disease or lead to life-threatening systemic infections. Staphylococcus aureus is the most common cause of skin infections. Treatment is complicated by continuous emergence of resistant S. aureus especially methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant S. aureus (VRSA). Therefore, searching for new alternatives is essential to combat this escalating antibiotic resistance. Bacteriophage therapy is a promising solution in the post antibiotic area. Bacteriophage therapy confers safety and higher rate of success. In the present study, 10 bacteriophages (belonging to the family Siphoviridae and Myoviridae) were isolated with lytic activity against MRSA &VRSA isolated from skin infections. The strongest six of ten phages were characterized morphologically by a JOEL_JEM_1010 electron microscope, physically through evaluating their lytic activity against wide ranges of temperature (35–95° C), PH (3–10) and radiation doses (0.5–2.5kGy) and biologically by evaluating their host ranges and phage longevity (1–120 day) in vitro. Finally, the anti-Staphylococcal effect of the isolated bacteriophages was tested and revealed that they have alone activity (10, 12) and synergistic activity with vancomycin and erythromycin by increasing their inhibition zone diameters (16, 22) mm, respectively.

Antibiotic Sensitivity Pattern of Staphylococcus aureus Isolated from Various Dry Foods

Background: Staphylococcus aureus is a well-known pathogen responsible for a range of clinical and localized infections, including nosocomial methicillin-resistant S. aureus (MRSA) infections. The emergence of vancomycin-resistant S. aureus (VRSA) strains has further complicated treatment options. Globally, food-borne diseases (FBD), including those caused by S. aureus, pose significant public health concerns. This study investigates the prevalence and antibiotic resistance of S. aureus in ready-to-eat packaged foods in Dhaka, Bangladesh, to better understand food safety risks. Methods: Samples of ready-to-eat packaged foods were collected from superstores in Dhaka and transported to the laboratory under appropriate conditions. Bacterial isolation was performed using standard methods on Mannitol salt agar medium, followed by incubation at 37°C for 24 hours. Biochemical tests, including the Catalase Test, IMViC tests, and Coagulase Test, were conducted for bacterial identification. Antibiotic susceptibility testing was performed using the Kirby-Bauer method with a range of antibiotics including amoxicillin, gentamicin, penicillin, chloramphenicol, ciprofloxacin, ceftriaxone, cephradine, nalidixic acid, erythromycin, and azithromycin. Results: The study found that resistance among S. aureus strains varied significantly, from 0% for gentamicin to 100% for amoxicillin. Gentamicin was the most effective antibiotic, with 100% sensitivity, followed by chloramphenicol with 95% sensitivity. Of the samples, 2.5% showed resistance to six antibiotics, 12.5% were resistant to at least five antibiotics, and overall, 27.5% of the strains were multidrug-resistant. These results align with findings from similar studies conducted in China and Greece. Conclusion: The study highlights the significant presence of multidrug-resistant S. aureus in ready-to-eat packaged foods in Dhaka. Preventing staphylococcal food poisoning requires strict adherence to hygiene practices, proper food storage, and thorough cooking. Education of food handlers on Good Manufacturing Practices (GMP) and Good Hygienic Practices (GHP) is essential to reduce contamination risks. Further research on the impact of hygiene on the development of food-borne illnesses is recommended to enhance food safety measures.

Encapsulated virgin coconut oil as a nanoscale in vitro solution against multiple drug resistant Staphylococcus aureus

Niosomes are excellent nanoscale vehicular systems that can carry a variety of drugs and (bioactive) compounds entrapped inside them. Virgin coconut oil (VCO) is the finest grade of coconut oil that is highly enriched with phenolic content, antioxidant activity and also comprises medium chain triglycerides. In this work, niosomes were encapsulated with VCO synthesized by a simple chemical method. The electron microscopy confirmed that spherical nanostructured lipid carrier molecules with a diameter in the range of 180–190 nm were produced. A zeta potential value of −42 mV was a testimony that these nanovehicles were having good stability. The natural oil loaded nanocarrier spheres proved to be potent antibacterial nano-antibiotics against multiple drug resistant (MDR) bacteria. The antibacterial activity of these magic nano-spheres was found to be better than ZnO (metallic oxides) nanoparticles. The nano-antibiotics resulted in 17, 14 and 12 mm zones of inhibition against methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant S. aureus (VRSA) and a (general) MDR strain of S. aureus in contrast to nanoparticles that resulted in zones of inhibitions 7, 8 and 6 mm for the same bacterial strains. Niosomes prove to be an excellent nanocarrier system that can encapsulate a number of bio-active compounds.

Microbiological profile of chronic suppurative otitis media among patients attending outpatient clinics at alexandria main university hospital, Egypt

Background: Chronic suppurative otitis media (CSOM) is a major public health problem in Egypt and one of the most common diseases of the ear for all age groups. The prevalence and antibiogram of microorganisms associated with CSOM have been reported to vary with time and geographical area probably due to indiscriminate use of antibiotics. Prompt appropriate antimicrobial therapy can effectively reverse the disease process, thereby preventing long term sequels. Hence, the periodic update of the prevalence and antibiogram of the etiological agents for CSOM would be helpful in management of patients. Methods and materials: A cross-sectional study was conducted on 143 patients with active CSOM attending the outpatient clinics of the Otorhinolaryngology Department at Alexandria Main University Hospital (AMUH) over a period of one year from September 2017 to August 2018. Ear discharge samples were aseptically collected using sterile cotton swabs and analyzed by the standard microbiological procedures. Data were analyzed using SPSS (Statistical Package for Social Science) version 21 software. Results: Pathogens were isolated from 95.00% of samples with a total of 153 isolates. Pseudomonas aeruginosa (24.83%), Staphylococcus aureus (S. aureus) (22.22%) and Proteus mirabilis and coagulase-negative staphylococci (13.07% each) were the dominant bacterial isolates. Anaerobes represented only 1.31% of the bacterial isolates and comprised of Peptostreptococcus and Bacteroides spp. Fungi were isolated from 14.38% of samples and comprised of Aspergillus flavus (45.83%), Aspergillus niger (25.00%), Candida albicans and non-albicans Candida (12.50% each) and Penicillium spp. (4.17%). Half of S. aureus isolates (50.00%) were methicillin-resistant S. aureus (MRSA), while 3 (8.82%) were vancomycin-resistant S. aureus (VRSA). Seventy-one (46.41%) aerobic bacterial isolates were multi-drug resistant (MDR), while 6 (3.92%) were pan-drug resistant (PDR). Only 50.33% of aerobic bacterial isolates were sensitive to ciprofloxacin which is the standard antibiotic prescribed by physicians at the outpatient clinics at AMUH. Conclusion: The most common causes of the studied CSOM infections were Pseudomonas aeruginosa and S. aureus.Treatment of CSOM should be based on results of culture and antibiotic susceptibility tests instead of empirical treatment to avoid emergence of MDR and PDR bacteria. Fungal culture should be considered in CSOM, since fungal infection can occur without specific signs and symptoms.

Resistance Rates of the most Isolated Bacteria from different Clinical Samples, Kerbala, Iraq

Determining the bacterial causative agents of infections by identifying their antimicrobial patterns will enable health institutions to limit the unnecessary use of antibiotics, and take active ways in preventing the spread of drug-resistant bacteria. This study aimed to identify the most common bacterial isolates responsible for infection and their antibiotic resistance rates. The results showed that Escherichia coli, Staphylococcus aureus (S aureus), and Pseudomonas aeruginosa (P. aeruginosa) represent the most common bacteria isolated with a percentage of 23.9, 18.8, and 16.2%, respectively. High resistance rates were found for the most common bacterial isolates. Other important findings are the presence of extended-spectrum B-lactamase (ESBL) producing bacteria and the appearance of hetero-resistance phenomenon. Moreover, the bacterial infection is mainly occurring in men. No significant correlation was observed in the type of isolated bacteria with patient admission status. E. coli strains were found to be highly resistant to amoxicillin-clavulanic acid, ceftriaxone (88.9%), ceftazidime (85.2%), trimethoprim-sulfamethoxazole (74.1%), and ciprofloxacin (59.3%). Whereas, the highest sensitivity rates were seen with meropenem antibiotic (92.6%). Concerning S. aureus isolates, 100, and approximately 91% of resistant rates were seen to penicillin and cefoxitin, respectively [methicillin-resistant S. aureus (MRSA)]. Approximately 50% of MRSA were vancomycin-resistant S. aureus (VRSA). Resistant rates of P. aeruginosa isolates to gentamycin and ciprofloxacin were 47.1%, amikacin 41.2%, and levofloxacin 35.3%. In conclusion, the current study might reveal that the isolated bacteria could be of critical priority carbapenem-resistant P. aeruginosa, and carbapenem-resistant and 3rd generation cephalosporin-resistant E. coli. In addition, the isolation of high priority bacteria includes vancomycin-resistant methicillin-resistant S. aureus.

Phylogeny of hospital acquired MRSA, and its comparative phenotypic clinico-epidemiology with vancomycin resistant S. aureus (VRSA)

Staphylococcus aureus is emerging as complicated pathogen because of its wide-ranging origin, multiple variants, and compromised antibiotic susceptibilities. Current study was planned to find lineage of hospital acquired methicillin resistant Staphylococcus aureus (HA-MRSA), and its comparative phenotypic clinico-epidemiology with vancomycin resistant S. aureus (VRSA). A total of (n = 200) samples were aseptically collected from wound, nose, and cerebrospinal fluid of patients from metropolitan and rural background hospitals along with on spot filling in of questionnaire. Phylogenetic analysis of HA-MRSA was identified by targeting mecA gene in S. aureus. At optimal tree branch length of 1.91 and evolutionary distance 0.1, high level sequence similarity (97%–99%) was observed with different strains of S. aureus isolated from both human and animal. Non-descriptive statistics at 5% probability found 61% S. aureus, while 43.44% of them were HA-MRSA, 92.62% VRSA, and 42.62% were both MRSA and VRSA. Among assumed risk factors, use of antibiotics, venous catheterization, chronic disease, pre-hospital visits, and ICU admitted patients showed significant association (p<0.05) with pathogen. HA-MRSA was 37.50%, 80%, and 37.50% sensitive to chloramphenicol, gentamicin, and oxacillin, respectively. While <50% of VRSA were sensitive against oxacillin, enoxacin, and chloramphenicol. A significant difference (p<0.05) of percentage responses of MRSA and VRSA at resistant, intermediate, and sensitive cadre against all antibiotics except chloramphenicol was obvious in this study. The Current study concluded higher prevalence of MRSA & VRSA, significant association of risk factors, limiting antibiotic susceptibility profile, and genetic transfer at animal-human interface which suggests further studies cum preventive strategies to be planned.

Synthesis, ADMET Properties, and In Vitro Antimicrobial and Antibiofilm Activity of 5-Nitro-2-thiophenecarbaldehyde N-((E)-(5-Nitrothienyl)methylidene)hydrazone (KTU-286) against Staphylococcus aureus with Defined Resistance Mechanisms.

The emergence of drug-resistant Staphylococcus aureus is responsible for high morbidity and mortality worldwide. New therapeutic options are needed to fight the increasing antimicrobial resistance among S. aureus in the clinical setting. We, therefore, characterized the in silico absorption, distribution, metabolism, elimination, and toxicity (ADMET) and in vitro antimicrobial activity of 5-nitro-2-thiophenecarbaldehyde N-((E)-(5-nitrothienyl)methylidene)hydrazone (KTU-286) against drug-resistant S. aureus strains with genetically defined resistance mechanisms. The antimicrobial activity of KTU-286 was determined by CLSI recommendations. The ADMET properties were estimated by using in silico modeling. The activity on biofilm integrity was examined by crystal violet assay. KTU-286 demonstrated low estimated toxicity and low skin permeability. The highest antimicrobial activity was observed among pan-susceptible (Pan-S) S. aureus (minimal inhibitory concentration (MIC) 0.5–2.0 µg/mL, IC50 = 0.460 µg/mL), followed by vancomycin resistant S. aureus (VRSA) (MIC 4.0 µg/mL, IC50 = 1.697 µg/mL) and methicillin-resistant S. aureus (MRSA) (MIC 1.0–16.0 µg/mL, IC50 = 2.282 µg/mL). KTU-286 resulted in significant (p < 0.05) loss of S. aureus biofilm integrity in vitro. Further studies are needed for a better understanding of safety, synergistic relationship, and therapeutic potency of KTU-286.

Design, synthesis of novel 4,5-dihydroisoxazole-containing benzamide derivatives as highly potent FtsZ inhibitors capable of killing a variety of MDR Staphylococcus aureus

Antibiotic resistance among clinically significant bacterial pathogens, such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant S. aureus (VRSA) is becoming a prevalent threat to public health, and new antibacterial agents with novel mechanisms of action hence are in an urgent need. As a part of continuing effort to develop antibacterial agents, we rationally designed and synthesized two series of 4,5-dihydroisoxazol-5-yl and 4,5-dihydroisoxazol-3-yl-containing benzamide derivatives that targeted the bacterial cell division protein FtsZ. Evaluation of their activity against a panel of Gram-positive and -negative pathogens revealed that compound A16 possessing the 4,5-dihydroisoxazol-5-yl group showed outstanding antibacterial activity (MIC, ≤0.125–0.5 μg/mL) against various testing strains, including methicillin-resistant, penicillin-resistant and clinical isolated S. aureus strains. Besides, further mouse infection model revealed that A16 could be effective in vivo and non-toxic to Hela cells. Finally, a detailed discussion of structure-activity relationships was conducted, referring to the docking results. It is worth noting that substituting a 4,5-dihydroisoxazole ring for the isoxazole ring not only broadened the antibacterial spectrum but also resulted in a significant increase in antibacterial activity against S. aureus strains. Taken together, these results suggest a promising chemotype for the development of new FtsZ-targeting bactericidal agents.

ZnO nanoparticles inhibit growth and biofilm formation of vancomycin-resistant S. aureus (VRSA)

Abstract The issue of antibiotic resistance has been considered as the greatest threats worldwide, which occurs naturally, but can accelerate due to the irrational administration of antibiotics in animals and humans. The consumption of vancomycin (VM) with the increasing occurrence of methicillin-resistant Staphylococcus aureus (MRSA) has been increased. As a consequence, strains of S. aureus resistant to VM have started to emerge. Therefore, the measures need to be taken to provide a spare line of treatment for this problem. In the current study, the antibacterial and antibiofilm-formation activities of the zinc oxide nanoparticles (ZnO-NPs) were assessed against vancomycin-resistant S. aureus (VRSA). The results revealed that a strong inhibitory effect was shown by ZnO-NPs against VRSA, where the zones of inhibition were 10–36 mm, and minimum inhibitory concentration (MIC) was 625 μg/ml. Moreover, the viability of bacteria was exponentially decreased with the increasing of the concentration of ZnO-NPs. ZnO-NPs also inhibited the biofilm production in a dose-dependent mannerwhere the highest rate of inhibition was 73.95±2.17% at 10 mg/ml of ZnO-NPs. To conclude, a significant antibacterial and antibiofilm activities of ZnO-NPs against VRSA were suggested.

Synthesis and biological evaluation of semi-synthetic albocycline analogs

Albocycline (ALB) is a unique macrolactone natural product with potent, narrow-spectrum activity against methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-intermediate (VISA), and vancomycin-resistant S. aureus (VRSA) strains (MIC = 0.5–1.0 μg/mL). Described herein is the synthesis and evaluation of a novel series analogs derived from albocycline by functionalization at three specific sites: the C2-C3 enone, the tertiary carbinol at C4, and the allylic C16 methyl group. Exploration of the structure-activity relationships (SAR) by means of minimum inhibitory concentration assays (MICs) revealed that C4 ester analog 6 was twice as potent as ALB, which represents a class of lead compound that can be further studied to address multi-drug resistant pathogens.

Vancomycin and linezolid resistance among multidrug-resistant Staphylococcus aureus clinical isolates and interaction with neutrophils

BackgroundDeveloped drug resistance against vancomycin and linezolid is a huge worrisome. The aim of our study was to investigate the rate of vancomycin and linezolid resistance in multidrug-resistant (MDR) Staphylococcus aureus (S. aureus) in Baghdad, Iraq. MethodsThree-hundred S. aureus were identified from various clinical origins in Baghdad, Iraq. Methicillin-and linezolid-resistant S. aureus (MRSA and LRSA, respectively) isolates were determined by disc diffusion, agar dilution and E-test methods. Biofilm formation was assayed using microtiter tissue plate (Mtp) assay. Polymerase chain reaction (PCR) was employed to detect the mecA, vanA, B, C, cfr and adhesin genes, followed by gene sequencing. Vancomycin-resistant S. aureus (VRSA) and LRSA strains interactions with neutrophils was assessed using flow-cytometry technique. ResultsTwo-hundred (67%) isolates were MRSA. One-hundred one (50.5%) and 44 (22%) MRSA were strong and moderate-level biofilm producers, respectively. All the strong biofilm-producer MRSA carried the clfA, clfB, fnbA, fnbB, fib and eno genes. Five (1.66%) and nine (3%) of the MRSA were VRSA and LRSA, respectively which were mostly isolated from blood and tissue infections. The vanA and cfr genes were detected in two and three MRSA, respectively. Three VRSA and two LRSA strains were strong biofilm-producers and contained adhesin genes (clfA, clfB, fnbA, fnbB, eno, fib, cna and ebps, but not bbp). The neutrophils mean apoptosis rate by the VRSA and LRSA strains included 80% and 66.7%, respectively. ConclusionVirulent MRSA rate was high. In addition, MRSA, VRSA and LRSA contained adhesin genes responsible for colonization and biofilm formation. Furthermore, these strains induced the neutrophils apoptosis. The evolution of pathogenic VRSA and LRSA is a concern towards eradication of MDR-S. aureus. More detailed works will be helpful to disclose the role of bacterial components in the biofilm formation and apoptosis and control strategies.

Prevalence of vanA Gene among Methicillin Resistant S. aureus Strains Isolated from Burn Wound Infections in Menoufia University Hospitals

Background: Staphylococcus aureus is a leading cause of burn wound infection. Vancomycin resistance among methicillin-resistant Staphylococcus aureus (MRSA) is becoming a worldwide growing threat. Objectives: to detect the prevalence of MRSA in burn patients and its antibiotic susceptibility patterns. In addition, the resistance patterns of MRSA to vancomycin and the prevalence of vanA gene among MRSA isolates were investigated. Methodology: A total 250 clinical samples were obtained from patients admitted to Burn Unit in Menoufia University Hospitals. Identification and antimicrobial susceptibility testing of S. aureus isolates were performed. Cefoxitin disk diffusion method was used to identify MRSA strains. Vancomycin resistance was determined by agar dilution method. Detection of mecA and vanA genes by multiplex PCR was done. Results: Staphylococcus aureus represented 43.3% of all isolates. By cefoxitin disc diffusion method, 94% (79/84) of isolated S. aureus were MRSA that showed a high resistance to most antimicrobials used with rates ranged from 40.5 % to 100%. Phenotypically among MRSA isolates, vancomycin sensitive S. aureus (VSSA), vancomycin-intermediate S. aureus (VISA) and vancomycin-resistant S. aureus (VRSA) were 59.5%, 15.2%, 25.3% respectively. Among MRSA isolates, 17 (21.5%) isolates had vanA gene by PCR (16 isolates were VRSA and one isolate was VSSA).Conclusion: This study is considered as an alarm demonstrating that implementation of proper infection control measures is mandatory to control spread of such resistant strains in our hospital.

Increasing production of the antibiotic-abyssomicin C in Micromonospora maris

Abyssomicin C is a polyketide antibiotic produced by Micromonospora maris AB-18-032. Previous work on abyssomicin C indicated that it inhibits growth of infectious pathogens such as Methicillin-resistant S. aureus (MRSA) and vancomycin-resistant S. aureus (VRSA). It does this by suppressing para-aminobenzoic acid (pABA) synthesis, which is required for folic acid biosynthesis in bacteria. This makes abyssomicin C an appealing antibiotic drug, as it is specific only to bacteria. However, its yield in chemical synthesis (4 %) and biosynthesis (60.0 mg/L) are low. Ribosome engineering, through the selection of streptomycin-resistant and rifampin-resistant mutants, of M. maris may result in strains with a higher titer of production. After screening by bioassay and sequencing, the mutant genes in six Ochi mutants were identified. Of these mutants, four of them are able to produce a higher titer of abyssomicin C. The other two strains were detected to produce the other secondary metabolite.