Vancomycin-resistant Staphylococcus Aureus Isolates Research Articles

Surface-functionalized UIO-66-NH2 for dual-drug delivery of vancomycin and amikacin against vancomycin-resistant Staphylococcus aureus

BackgroundConventional antibacterial compounds can inhibit the growth of microorganisms, but their adverse effects and the development of drug limit their widespread use. The current study aimed to synthesize PEG-coated UIO-66-NH2 nanoparticles loaded with vancomycin and amikacin (VAN/AMK-UIO-66-NH2@PEG) and evaluate their antibacterial and anti-biofilm activities against vancomycin-resistant Staphylococcus aureus (VRSA) clinical isolates.MethodsThe VAN/AMK-UIO-66-NH2@PEG were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and dynamic light scattering (DLS) to determine their size, polydispersity index (PDI), encapsulation efficiency (EE%), zeta-potential, drug release profile, and physical stability. Antibacterial activity was evaluated using minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and time-kill assays. Biofilm formation by VRSA was assessed using the crystal violet (CV) and minimum biofilm eradication concentration (MBEC) assays. The effect of sub-MIC concentrations of the formulations on the expression of biofilm-related genes (icaA, icaD) and resistance-related genes (mecA, vanA) was investigated using quantitative real-time polymerase chain reaction (RT-qPCR).ResultsAs demonstrated by MIC, MBC and time-kill assay, the VAN/AMK-UIO-66-NH2@PEG nanoparticles exhibited enhanced antibacterial activity against VRSA isolates compared to free drugs and prepared formulations. Furthermore, CV and MBEC tests indicated that the VAN/AMK-UIO-66@NH2/PEG can reduce biofilm formation dramatically compared to VAN/AMK and VAN/AMK-UIO-66@NH2, due to its great drug release properties. This study also found that the expression level of the mecA, vanA, icaA, and icaD genes in VAN/AMK-UIO-66@NH2/PEG treated VRSA isolates was substantially decreased compared to other groups.ConclusionsThese findings highlighted the efficiency of VAN/AMK-UIO-66@NH2/PEG in combating antimicrobial resistance and biofilm formation in VRSA isolates. Future studies, particularly in vivo models, are necessary to evaluate the safety, efficacy, and clinical applicability of these nanoparticles for the treatment of bacterial infections.

Molecular distribution of biocide resistance genes and susceptibility to biocides among vancomycin resistant Staphylococcus aureus (VRSA) isolates from intensive care unit (ICU) of cardiac hospital- A first report from Pakistan

BackgroundThe study was conducted with the aim to investigate the VRSA isolates in terms of their susceptibility to routinely used biocides influenced by the co-occurrence of biocide resistant gene (BRGs) and efflux pumps genes. MethodologyFrequently touched surfaces within intensive care unit (ICU) of cardiac hospital were classified into three primary sites i.e., structure, machines and miscellaneous. Over a period of six months (January 2021 to July 2021) twenty three swabs samples were collected from these sites. Subsequently, these samples underwent both phenotypic and molecular methods for VRSA isolation and identification. Susceptibility and efficacy testing of biocides (benzalkonium chloride (BAC), cetrimide (CET) and chlorhexidine gluconate (CHG)) were evaluated using microdilution broth and suspension method. Furthermore, specific primers were used for singleplex PCR targeting BRGs (cepA, qacA, and qacE) and efflux pump (norA, norB, norC, sepA, mepA and mdeA) associated genes. ResultsWe found that 72.2 % S. aureus demonstrate the presence of vanA or vanB genes with no significant difference among three sites (p > 0.05). cepA is the most dominant BRGs followed by qacA and qacE from structure site as compared to other sites (p < 0.05). BAC showed reduced biocide susceptibility and MIC50. There was no significant difference between presence or absence of BRGs and high MIC values of VRSA isolates from all three sites. However, efflux pump genes (EFPGs) particularly norA and norA + sepA had a significant association with BRGs and reduced biocide. ConclusionBAC is the most effective disinfectant against VRSA. Proper and controlled use of BAC is required to overcome the VRSA contamination. We recommend continuous monitoring of the BRGs prevalence for better prevention of microorganism dissemination and infection control in hospitals.

Molecular characterization of vancomycin-resistant Staphylococcus aureus isolated from bovine milk.

Vancomycin-resistant Staphylococcus aureus (VRSA) is a zoonotic life-threatening pathogen. Vancomycin exhibits anti-bacterial activity by inhibiting peptidoglycan synthesis by binding to the D-ala-D-ala terminus of the peptidoglycan. But in VRSA, D-ala-D-ala is replaced by D-ala-D-lactate due to the presence of vanA, vanB or vanD genes. This study was intended to identify the molecular prevalence of VRSA in 768 bovine milk samples, risk factor association, antibiogram profile and bioinformatics analysis of VRSA by targeting vanB gene. Out of a total of 248 S. aureus isolates from mastitic milk samples, the phenotypic and genotypic prevalence of VRSA was estimated to be 17.74% and 10.89%, respectively. Farm-level risk factors including use of improper milking technique, lack of milker's care during milking, unhygienic conditions during milking and no dry cow therapy were found to be significantly associated (p < 0.05). Anti-microbial susceptibility testing of VRSA isolates exhibited the highest resistance to oxytetracycline, followed by oxacillin and Trimethoprim+sulfamethoxazole. The current study sequences showed more resemblance with reported sequences from Iraq (MN747834) and Egypt (MK095504, MK087830), which belong to vanB gene from S. aureus as compared to sequences from other countries, which belong to vanB gene from the genus Enterococcus. The Genetic Algorithm for Recombination Detection (GARD) found 234 potential breakpoints, translating into a search room of 123,883,305 models with up to 4 breakpoints. The phylogenetic motif profiling method discovered evolutionarily conserved residues across target genes' homologous protein sequences. These residues were discovered to be conserved in drug-resistant target proteins over the evolutionary process and may play a key role in their function. The current study revealed a molecular prevalence of VRSA in dairy animals, along with molecular analysis of vancomycin resistance in S. aureus by targeting the vanB gene using standard bioinformatics tools. The occurrence of VRSA in animals requires serious attention because this pathogen has zoonotic potential, so it can become a greater risk to consumer health.

Genomic Analysis of Vancomycin-Resistant Staphylococcus aureus Isolates from the 3rd Case Identified in the United States Reveals Chromosomal Integration of the vanA Locus.

Vancomycin-resistant Staphylococcus aureus (VRSA) is a human pathogen of significant public health concern. Although the genome sequences of individual VRSA isolates have been published over the years, very little is known about the genetic changes of VRSA within a patient over time. A total of 11 VRSA, 3 vancomycin-resistant enterococci (VRE), and 4 methicillin-resistant S. aureus (MRSA) isolates, collected over a period of 4.5 months in 2004 from a patient in a long-term-care facility in New York State, were sequenced. A combination of long- and short-read sequencing technologies was used to obtain closed assemblies for chromosomes and plasmids. Our results indicate that a VRSA isolate emerged as the result of the transfer of a multidrug resistance plasmid from a coinfecting VRE to an MRSA isolate. The plasmid then integrated into the chromosome via homologous recombination mediated between two regions derived from remnants of transposon Tn5405. Once integrated, the plasmid underwent further reorganization in one isolate, while two others lost the staphylococcal cassette chromosome mec element (SCCmec) determinant that confers methicillin-resistance. The results presented here explain how a few recombination events can lead to multiple pulsed-field gel electrophoresis (PFGE) patterns that could be mistaken for vastly different strains. A vanA gene cluster that is located on a multidrug resistance plasmid that is integrated into the chromosome could result in the continuous propagation of resistance, even in the absence of selective pressure from antibiotics. The genome comparison presented here sheds light on the emergence and evolution of VRSA within a single patient that will enhance our understanding VRSA genetics. IMPORTANCE High-level vancomycin-resistant Staphylococcus aureus (VRSA) began to emerge in the United States in 2002 and has since then been reported worldwide. Our study reports the closed genome sequences of multiple VRSA isolates obtained in 2004 from a single patient in New York State. Our results show that the vanA resistance locus is located on a mosaic plasmid that confers resistance to multiple antibiotics. In some isolates, this plasmid integrated into the chromosome via homologous recombination between two ant(6)-sat4-aph(3') antibiotic resistance loci. This is, to our knowledge, the first report of a chromosomal vanA locus in VRSA; the effect of this integration event on MIC values and plasmid stability in the absence of antibiotic selection remains poorly understood. These findings highlight the need for a better understanding of the genetics of the vanA locus and plasmid maintenance in S. aureus to address the increase of vancomycin resistance in the health care setting.

Inhibition of the Vancomycin Resistance in Staphylococcus aureus in Egypt Using Silver Nanoparticles.

Staphylococcus aureus is a major human pathogen that is sometimes resistant to vancomycin. In this study, the prevalence of vancomycin-resistant Staphylococcus aureus (VRSA) was studied. 100 isolates of S. aureus were identified based on biochemical and molecular evidence. The antibiotic susceptibility of the studied isolates was tested against 13 antibiotics by the disc diffusion method that showed 24 vancomycin-resistant isolates. The minimum inhibitory concentrations (MICs) were estimated by the agar dilution method to determine vancomycin intermediate-resistant S. aureus (VISA) and VRSA. The resistance gene cluster (vanA, vanR, vanH, and vanY) was amplified by PCR and then sequenced. Amplification of vanA and vanR genes showed that they are present in 21.4% and 14.3% of VRSA isolates, respectively, whereas none of the studied genes has been detected in VISA strains. A significant antimicrobial effect toward VRSA isolates using silver nanoparticles (AgNPs) synthesized from S. aureus and rosemary leaves was recorded. This study confirmed the existence of VRSA strains in Egypt. Furthermore, the use of silver nanoparticles inhibits these vancomycin-resistant S. aureus strains in vitro.

Incidence of Vancomycin-Resistant Staphylococcus aureus Strains among Patients with Urinary Tract Infections.

There has been a substantial rise in the number of vancomycin-resistant Staphylococcus aureus (VRSA) strains during the last several years. The proportion of vancomycin-resistant strains among isolated S. aureus has risen steadily in recent years, with the first spike occurring in critical care units and thereafter in general hospital wards. S. aureus isolates from urinary tract infection patients were studied for their prevalence and antibiotic resistance. From 292 urine samples, 103 bacterial strains (35.3%) were identified as S. aureus. Various antibiotics were used to test the isolates’ antibacterial resistance profiles. Antibiotic resistance to erythromycin was found in most bacterial isolates, whereas tobramycin antibiotic sensitivity was found in most of them. Vancomycin resistance was found in 23 of all S. aureus isolates in this study. Analysis for β-lactamase found that 71% of S. aureus isolates were positive in all isolates. There was a single plasmid with a molecular weight of 39.306 Kbp in five selected VRSA isolates that was subjected to plasmid analysis. There was evidence of vancomycin resistance among the S. aureus isolates collected from UTI patients in this investigation. This vancomycin resistance pretenses a challenge in the treatment of S. aureus infections and the need to precisely recognize persons who require last-resort medication such as tobramycin.

Methicillin-Resistant Staphylococcus aureus (MRSA) Patterns and Antibiotic Susceptibility in Surgical and Non-Surgical Patients in a Tertiary Hospital in Indonesia

Methicillin-Resistant Staphylococcus aureus (MRSA) in the hospital is found mainly in surgical patients, which increases morbidity and mortality. Currently, vancomycin is the drug of choice for the treatment of MRSA infections. The increasing use of vancomycin and its inappropriate administration may increase the resistance of S. aureus to vancomycin. This study aimed to describe the distribution of MRSA and types of antibiotics that are still sensitive to MRSA in surgical and non-surgical patients. This cross-sectional, observational, retrospective descriptive study was conducted at the Microbiology Laboratory, Dr. Hasan Sadikin General Hospital, in 2019 using secondary data on the results of culture examination and antibiotic susceptibility of positive S. aureus culture isolates from all types of isolates from surgical and non-surgical patients. All specimens were cultured in appropriate media. Identification of S. aureus was performed by Gram staining to identify bacterial morphology, and automatic tools. Antibiotic susceptibility test was performed using an automatic machine. Seventy-five isolates (17%) were identified to be MRSA with 46 (53%) of them retrieved from surgical patients. Most of the MRSA isolates came from pus and were mostly due to skin infections. Antibiotic susceptibility results showed two Vancomycin-Resistant Staphylococcus aureus (VRSA) isolates from surgical patients. The positive culture of the MRSA and VRSA was dominated by surgical patients with pus coming from surgical wound infection, burn, and other skin infection as the most common sources. Thus, the proportion of MRSA isolates in the hospital in 2019 is 17% and two VRSA isolates are identified in the same year. The surgical ward was the primary origin of most MRSA isolates. Further studies are necessary to identify the MRSA incidence rate, evaluation and periodic monitoring of antibiotic use, and active surveillance in the surgical patient rooms.

Eradication of vancomycin-resistant Staphylococcus aureus on a mouse model of third-degree burn infection by melittin: An antimicrobial peptide from bee venom

Third-degree burn infections caused by antibiotic-resistant bacteria are of high clinical concern. Chemical antibiotics are not promising in eradication of bacterial infections. In this challenging condition, antimicrobial peptides (AMPs) are recently introduced as novel promising agents to overcome the issue. Accordingly, our study aimed to evaluate the efficiency of ‘melittin’ as natural peptide in bee venom, in eradicating vancomycin resistant Staphylococcus aureus (VRSA) on a mouse model of third-degree burn infection.In vitro pharmacological value of melittin was determined by examining its inhibitory and killing activities on VRSA isolates at different doses and time periods. The action mechanism of ‘melittin’ was evaluated by fluorescent release assay and Field Emission Scanning Electron Microscopy (FE-SEM) analyses. In vivo activity and toxicity of melittin were also examined on a mouse model of third-degree burn infection.The Minimum Inhibitory Concentration (MIC) and the Minimum Bactericidal Concentration (MBC) of melittin on all isolates ranged from ‘0.125–2 μg/mL’ and ‘0.125–4 μg/mL’, respectively. Rapid antibacterial activity of melittin on VRSA isolates was demonstrated by killing kinetics assays. Fluorometric and FE-SEM analyses indicated the membranolytic effects of melittin on VRSA isolates. The colonized VRSA bacteria were eradicated by melittin at 16 μg, in a single dose. No dermal toxicity and in vivo hemolysis were observed in the examined mice.The lack of in vivo toxicity of melittin along with its potent antibacterial activity indicated its promising therapeutic value as a topical drug against S. aureus associated third-degree burn infections.

Global prevalence and distribution of vancomycin resistant, vancomycin intermediate and heterogeneously vancomycin intermediate Staphylococcus aureus clinical isolates: a systematic review and meta-analysis

Vancomycin-resistant Staphylococcus aureus (VRSA), Vancomycin-intermediate S. aureus (VISA) and heterogeneous VISA (hVISA) are subject to vancomycin treatment failure. The aim of the present study was to determine their precise prevalence and investigate prevalence variability depending on different years and locations. Several international databases including Medline (PubMed), Embase and Web of Sciences were searched (data from 1997 to 2019) to identify studies that addressed the prevalence of VRSA, VISA and hVISA among human clinical isolates around the world. Subgroup analyses and meta-regression were conducted to indicate potential source of variation. Publication bias was assessed using Egger’s test. Statistical analyses were conducted using STATA software (version 14.0). Data analysis showed that VRSA, VISA and hVISA isolates were reported in 23, 50 and 82 studies, with an overall prevalence of 1.5% among 5855 S. aureus isolates, 1.7% among 22,277 strains and 4.6% among 47,721 strains, respectively. The overall prevalence of VRSA, VISA, and hVISA before 2010 was 1.2%, 1.2%, and 4%, respectively, while their prevalence after this year has reached 2.4%, 4.3%, and 5.3%. The results of this study showed that the frequency of VRSA, VISA and hVISA after 2010 represent a 2.0, 3.6 and 1.3-fold increase over prior years. In a subgroup analysis of different strain origins, the highest frequency of VRSA (3.6%) and hVISA (5.2%) was encountered in the USA while VISA (2.1%) was more prevalent in Asia. Meta-regression analysis showed significant increasing of VISA prevalence in recent years (p value ≤ 0.05). Based on the results of case reports (which were not included in the calculations mentioned above), the numbers of VRSA, VISA and hVISA isolates were 12, 24 and 14, respectively, among different continents. Since the prevalence of VRSA, VISA and hVISA has been increasing in recent years (especially in the Asian and American continents), rigorous monitoring of vancomycin treatment, it’s the therapeutic response and the definition of appropriate control guidelines depending on geographical regions is highly recommended and essential to prevent the further spread of vancomycin-resistant S. aureus.

Vancomycin-resistant Staphylococcus aureus isolated from camel meat and slaughterhouse workers in Egypt

BackgroundThe emergence of vancomycin-resistant Staphylococcus aureus (VRSA) represents a challenge for the treatment of staphylococcal infections in both human and animals worldwide. Although VRSA has been detected in several animal species worldwide, data on the bacterial prevalence in dromedary camels and workers in camel slaughterhouses are scarce.MethodsWe investigated meat samples from 200 dromedary camel carcasses from three different abattoirs that were being prepared to be sent to the markets. Twenty hand swabs were voluntarily collected from the workers in the same abattoirs. Isolation and identification of the bacterial specimens from the samples were performed using conventional cultural techniques and biochemical identification and were confirmed by PCR amplification of the nuc gene. Antimicrobial susceptibility against nine antimicrobial agents commonly used in human and camels was tested using the disc diffusion method, and genetic analysis was performed by evaluating the mecA gene in phenotypically oxacillin (OXA)- and cefoxitin (FOX)-resistant isolates. The resistance of S. aureus to vancomycin (VAN) was tested by broth microdilution and confirmed by PCR targeting the vanA and vanB genes. The vanA and vanB genes were sequenced.ResultS. aureus was detected in both camel meat (29/200, 14.5%) and in abattoir workers (11/20, 55%). Of the collected samples, 27% (8/29, camel) and 54% (6/11, human) were identified as VRSA.All VRSA isolates carried both the vanA and vanB genes. Additionally, all VRSA isolates were also classified as methicillin-resistant S. aureus (MRSA). The vanA amplicons of the isolates from human and camel meat were homologous and clustered with a Chinese reference isolate sequence.ConclusionThis study demonstrated that VRSA is present in camel abattoirs in Egypt. Zoonotic transmission between animals and human is probable and reflects both a public health threat and a food safety concern.

&lt;p&gt;Genetic characterization of two vancomycin-resistant &lt;em&gt;Staphylococcus aureus&lt;/em&gt; isolates in Kerman, Iran&lt;/p&gt;

AimThe aim of this study was the genetic characterization of two clinical vancomycin-resistant Staphylococcus aureus (VRSA) isolates.Materials and methodsResistance to vancomycin was determined by phenotypic method. PCR was used for detection of mecA, vanA, ermA, ermB, ermC, msrA/B, aph(2”)-Ic, aph(3ʹ)-IIIa, pvl, Immune Evasion Cluster [sea, sep, chip, sak and scn] genes and biofilm operon icaABCD. On the other hand, multilocus sequence typing and agr typing methods were performed for the determination of clonal relationship and van operon was detected and sequenced.ResultsVancomycin-resistant Staphylococcus aureus strain 1 (VRSA-1) was positive for vanA, ermA, ermC, aph(2”)-Ic, aph(3ʹ)-IIIa, sea, sep, icaD genes, belonging to agr type I; SCCmec type III; spa type t030; and ST239. However, the genetic characterization of Vancomycin-resistant Staphylococcus aureus strain 2 (VRSA-2) revealed the presence of various types of resistance genes vanA, ermA, ermC, aph(2”)-Ic, aph(3ʹ)-IIIa, sea, icaD, relating to agr type I; SCCmec type III; spa type t459; and ST239. The presence of transposon Tn1546 was determined by PCR sequencing.The Basic Local Alignment Search Tool analysis of van operon in the VRSA isolates showed 99.6% sequence homology to Tn1546 in vancomycin-resistant enterococci, indicating the vanA operon has an enterococcal origin.ConclusionIn conclusion, the ST239 is one of the most common clones of MRSA isolates which involved the hospital-associated infections, therefore, the emergence of VRSA isolates with ST239 increased the spread of resistance to vancomycin in the hospital settings.

VANCOMYCIN RESISTANT STAPHYLOCOCCUS AUREUS IN DR. WAHIDIN SUDIROHUSODO HOSPITAL MAKASSAR

Vancomycin Resistant Staphylococcus aureus (VRSA) refers to bacteria that have complete resistance to Vancomycin. The increasing prevalence of VRSA can be a significant clinical problem with the limited therapeutic options. Therefore, the identification of VRSA is necessary to improve the management of antibiotic therapy, infection control and to prevent the occurrence of wider resistance. This retrospective descriptive study used secondary data of antibiotic susceptibility test on Staphylococcus aureus identified using VITEK 2 and patient medical records from January 2015 to December 2016. The data is processed using SPSS. Of 387 Staphylococcus aureus isolates obtained, 45 (11%) were VRSA. The most common VRSA isolates were male patients (57.8%) with the mean age being 41-60 years old (35.6%). The treatment ward with the most VRSA isolates were from surgical ward (20%), and internal medicine ward (15.6%) whereas the VRSA isolates from outpatient record were from surgical department (8.9%), dermatology department and ENT department (2.2%). The most common specimens were blood (28.9%), pus (26.7%), and sputum (20.0%). The highest prevalence of VRSA was found in the use of ≥ 3 invasive medical devices and from clinical outcome was found 11 (24.4%) of the patients died. Linezolid, Quinupristin / Dalfopristin, Tigecycline, and Nitrofurantoin as a therapeutic option have &gt; 90% sensitivity. Identification of VRSA in Dr. Wahidin Sudirohusodo Hospital Makassar emphasized the need for immediate action by infection control division, especially in related units to prevent the transmission.

Reports of Vancomycin-Resistant Staphylococcus aureus from Middle East Countries

Context: Staphylococcus aureus is one of the most important pathogens worldwide. The emergence of methicillin-resistant Staphylococcusaureus (MRSA) made vancomycin as the only therapeutic choice. Due to excessive use of vancomycin, decreased susceptibility and increased resistance against this antibiotic are reported worldwide. The current study aimed at investigating the emergence of vancomycin-resistant Staphylococcus aureus (VRSA) in different regions of the Middle-East. Evidence Acquisition: All reputable databases, such as Google Scholar and PubMed, were screened for articles and abstracts reporting VRSA in the Middle-East by the appropriate keywords. Reliable phenotypic and genotypic studies were included in the current review. Results: Reviewing all articles/abstracts revealed more than 100 reports of VRSA isolates from the Middle-East. Most of the studies did not use the clinical and laboratory standards institute (CLSI) guidelines on VRSA identification. Until 2012, four VRSA strains were reported from Iran, 7 from Egypt, and 1 from Pakistan. From 2012 to 2016, seven VRSA isolates were added to the global statistics from the Middle-East; 1 from Iran and 6 from Egypt. Conclusions: VRSA is a global health threat. According to the expanding reports on the emersion of VRSA, more attention should be paid to the proper prescription of this antibiotic as the only choice for S. aureus infections.

The role of cell wall thickness and van genes in clinical strains of vancomycin resistant Staphylococcus aureus

Ten vancomycin resistant Staphylococcus aureus (VRSA) isolates were detected in a previous study, five out of them harbored vanA gene. The current study focused on the role of other van genes and mechanisms related to cell wall thickness in the development of vancomycin resistance in these VRSA isolates. The ten VRSA and five vancomycin sensitive Staphylococcus aureus (VSSA) isolates were re-tested by conventional methods in three different laboratories and their identification and sensitivity were confirmed. Multiplex polymerase chain reaction was performed for the detection of vancomycin vanA, vanB, vanC1/2, vanD, vane, and vanG resistance encoding genes as well as S. aureus specific nuc gene. All 15 isolates were molecularly confirmed as S. aureus and five of them were harboring the vanA gene. Other tested vancomycin encoding genes, namely vanB, vanC1/2, vanD, vanE, vanG were not detected in these isolates. Cell wall thickness was measured by transmission electron microscopy in the 15 tested isolates. The mean cell wall thickness was 40.5 ± 2.8, 22.6 ± 4.6, 31.2 ± 10.3, 23.2 ± 5.6 nm for vanA gene positive, vanA negative, VRSA, VSSA isolates, respectively. There was statistically significant difference between the cell wall thickness of vanA positive (+) and vanA negative (-) isolates, while no significant difference between VRSA and VSSA isolates. In conclusion, cell wall thickness was associated with the presence of vanA gene and this thickness was present in 50% of the tested VRSA isolates. Hence, it seems safe to assume that vancomycin resistance can be multifactorial.

Biological Characters of Vancomycin Resistant Staphylococcus aureus Isolates from a University Hospital in Egypt

Background: Vancomycin resistance in Staphylococcus aureus in many cases appears to be associated with some biological changes. Methods and Findings: In this study 88 vancomycin resistant Staphylococcus aureus (VRSA) were isolated from Tanta. Antibiotic susceptibility test was performed. Some of its biological characters were studied including autolytic activity, coagulase production, surface hydrophobicity and biofilm formation. Conclusion: As observed, vancomycin MICs of the selected VRSA isolates were directly proportional to their hydrophobicity index and biofilm production. On the other hand, MICs were inversely proportional to coagulase activity (the higher the dye diffusion, the lower the coagulase activity).

Vancomycin-Resistant Staphylococcus aureus - Delaware, 2015.

Vancomycin-resistant Staphylococcus aureus (VRSA) is a rare, multidrug-resistant bacterium of public health concern that emerged in the United States in 2002. VRSA (S. aureus with vancomycin minimum inhibitory concentration [MIC] ≥16 μg/mL) arises when vancomycin resistance genes (e.g., the vanA operon, which codes for enzymes that result in modification or elimination of the vancomycin binding site) from vancomycin-resistant enterococci (VRE) are transferred to S. aureus (1). To date, all VRSA strains have arisen from methicillin-resistant S. aureus (MRSA). The fourteenth VRSA isolate (VRSA 14) identified in the United States was reported to CDC in February 2015.

Epidemiological survey of the first case of vancomycin-resistant Staphylococcus aureus infection in Europe.

We report on the follow-up and epidemiological study triggered by the isolation of the first vancomycin-resistant Staphylococcus aureus (VRSA) detected in Europe. The patient and 53 close contacts were screened for S. aureus colonization and all isolates recovered were characterized by multiple molecular typing methods. The VRSA remained confined to the infected foot of the patient and was not detected in any of the close contacts. Nasal colonization with S. aureus was detected in 20 subjects, of whom 15 carried methicilin-susceptible isolates with the remaining five harbouring methicilin-resistant S. aureus (MRSA). The majority of the isolates belonged to clones that have been previously shown to be prevalent in Portugal, both in the hospital setting and in the community. Only one isolate, an MRSA, was closely related to the VRSA. Like most of the characterized VRSA isolates from other countries, the VRSA isolated in Portugal belonged to clonal complex (CC) 5. Despite the absence of VRSA dissemination, the recent increase in the incidence of lineages belonging to CC5 in some European countries, including Portugal, may result in more frequent opportunities for the emergence of VRSA.

The Role of the Staphylococcal VraTSR Regulatory System on Vancomycin Resistance and vanA Operon Expression in Vancomycin-Resistant Staphylococcus aureus

Vancomycin is often the preferred treatment for invasive methicillin-resistant Staphylococcus aureus (MRSA) infection. With the increase in incidence of MRSA infections, the use of vancomycin has increased and, as feared, isolates of vancomycin-resistant Staphylococcus aureus (VRSA) have emerged. VRSA isolates have acquired the entercoccal vanA operon contained on transposon (Tn) 1546 residing on a conjugal plasmid. VraTSR is a vancomycin and β-lactam-inducible three-component regulatory system encoded on the S. aureus chromosome that modulates the cell-wall stress response to cell-wall acting antibiotics. Mutation in vraTSR has shown to increase susceptibility to β-lactams and vancomycin in clinical VISA strains and in recombinant strain COLVA-200 which expresses a plasmid borne vanA operon. To date, the role of VraTSR in vanA operon expression in VRSA has not been demonstrated. In this study, the vraTSR operon was deleted from the first clinical VRSA strain (VRS1) by transduction with phage harvested from a USA300 vraTSR operon deletion strain. The absence of the vraTSR operon and presence of the vanA operon were confirmed in the transductant (VRS1Δvra) by PCR. Broth MIC determinations, demonstrated that the vancomycin MIC of VRS1Δvra (64 µg/ml) decreased by 16-fold compared with VRS1 (1024 µg/ml). The effect of the vraTSR operon deletion on expression of the van gene cluster (vanA, vanX and vanR) was examined by quantitative RT-PCR using relative quantification. A 2–5-fold decreased expression of the vanA operon genes occured in strain VRS1Δvra at stationary growth phase compared with the parent strain, VRS1. Both vancomycin resistance and vancomycin-induced expression of vanA and vanR were restored by complementation with a plasmid harboring the vraTSR operon. These findings demonstrate that expression in S. aureus of the horizontally acquired enterococcal vanA gene cluster is enhanced by the staphylococcal three-component cell wall stress regulatory system VraTSR, that is present in all S. aureus strains.

Characterization of vancomycin-resistant Staphylococcus aureus in the National Liver Institute

Objective The aim of the study was to assess vancomycin-resistant Staphylococcus aureus (VRSA) in the National Liver Institute. Background VRSA refers to the strains of S. aureus that have become resistant to vancomycin. Three classes of VRSA have emerged: vancomycin intermediate-resistant S. aureus, heterogenous vancomycin-intermediate S. aureus, and high-level VRSA. Materials and methods The study was carried out on 705 samples that were collected from patients, personnel, and hospital environments. Group I (the patient group) included samples from 555 patients. From them different microbiological samples were collected (blood, urine, sputum, wound aspiration, nasal swab, throat swab, drains, and endotracheal tubes). Group II (the personnel group) included 45 samples from staff members who were in contact with the patients. Swabs were taken from their noses, throats, and fingertips. Group III (the hospital environment) included samples from 105 swabs. Samples from all groups were subjected to culture and isolation of the bacteria and identification of S. aureus isolates. These isolates were subjected to an antibiogram using the disc diffusion method, and testing for vancomycin susceptibility by the disc diffusion method, an E-test (E-test strip is Hi Media laboratories Pvt. Limited, Mumbai, India), and Vitek-2 compact (Vitek-2 is bioMιrieux, Inc., Durham, NC). VRSA isolates were subjected to analysis of plasmid DNA profile and restriction fragment length polymorphism (RFLP) PCR of isolated plasmids to detect the vanA gene. Results This study showed that, of 145 isolated S. aureus strains, 58.64% were vancomycin-sensitive S. aureus, 20.68% were vancomycin intermediate-resistant S. aureus, and 20.68% were VRSA. Their plasmid profile showed that 10% had no plasmid, 26.7% had one plasmid, 50% had two plasmids, and 13.3% had three plasmids. The molecular weight of most plasmids was 100 kb (36%). RFLP PCR for detection of the vanA gene in the isolated plasmids was positive in 51.9%. Conclusion VRSA prevalence in the National Liver Institute is 20.68%. The majority (90%) carried plasmids. Most plasmids had a molecular weight of 100 kb, and the vanA gene, as detected by RFLP PCR, was positive in 51.9%.

Genetic Analysis of a Vancomycin-Resistant Staphylococcus aureus Strain Isolated in Iran

In their recent paper, Kobayashi et al. evaluated the emergence of vancomycin-resistant Staphylococcus aureus (VRSA) by genomic analysis (1). Based on whole-genome sequencing data for all U.S. VRSA strains isolated to date (2), they proposed that the development of resistance to vancomycin is an independent event in VRSA strains. It was our pleasure to read their article. We found that our results are in concordance with their conclusions. Our VRSA isolate belongs to ST1283, CC8, Spa t037, SCCmec III, and agrI (3). These genetic features are specific to endemic Asian clones and distinct from those of U.S. VRSA isolates, which all belonged to CC5. Moreover, the plasmids of our VRSA isolate were different from routine VRSA plasmids, based on the HindIII digestion pattern and multiplex PCR for common staphylococcal or enterococcal plasmids (our unpublished data). Collectively, these data indicate that our VRSA isolate is different from previously described isolates and probably carries an uncommon type of vanA-containing plasmid. These findings support the assumption made by Kobayashi et al. regarding independent acquisition of vanA by S. aureus in different geographical areas. Hopefully, our future whole-genome sequencing of this strain will shed light on the matter.