MRSA Isolates Research Articles

Estimation of Biofilm Components and Prevalence of SDR Genes among Staphylococcus Aureus Isolated from Anbar Hospitals

Background Nosocomial infections, a major health problem, are due at 80% to biofilm‐associated infection. Staphylococcus aureus, a prominent biofilm producer, has both MRSA and MSSA biofilm-forming capabilities that highlight its persistence in hospital environments. In previous studies, less focus was given to the components of the biofilms. Therefore, understanding biofilm composition has become crucial. Objective In this study, the components in the biofilm matrix in MRSA and MSSA isolates were estimated, and the prevalence of sdr genes (sdrC,sdrD,sdrE) among S. aureus strains was investigated. Methods Between September, 2023 and January, 2024, a total of 200 specimens were collected from patients with suspected Staphylococcus aureus infections. Eighty-two isolates were identified as S. aureus from various sources, including wounds, nasal swabs, ear swabs, and blood, based on macroscopic, microscopic, and molecular properties. Biofilms were subjected to DNase and proteinase K treatment in order to identify their biochemical composition. Multiplex PCR was used to determine the distribution of sdr genes among isolates. Results The average reduction after treatment with proteinase K in MSSA biofilms (29.67±16.62) was significantly lower than in MRSA biofilms (46.21±26.33, p=0.032). Also, when treated with DNase, MRSA biofilms showed a greater average reduction (49.65±25.30) compared to MSSA biofilms (28.71±20.98, p=0.006). MRSA and MSSA biofilms also had different polysaccharide concentrations, with MSSA biofilms having significantly higher levels (206.86±82.92 μM/OD595) than MRSA biofilms (85.80±32.52 μM/OD595, p=0.005). The sdrC gene was most common in the gene profiles of MRSA (100%) and MSSA (50%). There was a strong association between the presence of the sdrD gene and methicillin-resistant S. aureus isolates (p < 0.001). Conclusion These findings indicate that the biofilms of MRSA isolates are largely composed of proteins and eDNA, while MSSA isolates rely on polysaccharides in their biofilms. The results indicate the importance of proteins encoded by SDR genes in the development of biofilm structure.

Reduced vancomycin susceptibility in Staphylococcus aureus clinical isolates: a spectrum of less investigated uncertainties

BackgroundStaphylococcus aureus clinical isolates with vancomycin MICs of 2 µg/ml have been associated with vancomycin therapeutic failure and the heterogenous vancomycin-intermediate S. aureus (hVISA) phenotype. While carriage of van genes has usually been associated with higher level of MIC and frank vancomycin resistance, the unrecognized risk of hetero-resistance is frequently underestimated. Methods used for assessing vancomycin susceptibility have also shown different concordance and variable performance and accessibility in routine clinical diagnostics posing a challenge to inform treatment selection in hospital settings.MethodsA total of 195 clinical samples were obtained among which 100 S. aureus isolates were identified. Ninety-six MRSA isolates have been identified using cefoxitin disc and mecA gene detection. The vanA and vanB genes have been screened for in the studied isolates using conventional PCR amplification. Examination of reduced vancomycin susceptibility has been performed using vancomycin screen agar, Broth Micro Dilution method (BMD), and VITEK2. Blood isolates were screened for hVISA using PAP-AUC method.ResultsVancomycin screening agar applied to 96 MRSA isolates revealed 16 isolates with reduced vancomycin susceptibility. Further MIC testing revealed that 7 isolates were VISA and only 1 isolate was identified as VRSA using both BMD MIC method and VITEK2. Among 24 tested blood isolates, 4 isolates (16.7%) revealed the hVISA phenotype as identified using PAP-AUC method. Using PCR, vanA gene was identified in 5 S. aureus isolates (5%). Three of them were VSSA while the other two isolates were VISA.ConclusionIn this study, we report the very low prevalence of VRSA among the tested S. aureus clinical isolates (1%) and the existence of hVISA phenotype among studied S. aureus blood isolates at the rate of 16.7% in our setting. Fifty percent (8/16) of isolates that demonstrated reduced vancomycin susceptibility using vancomycin agar screen tested susceptible using both broth dilution method and VITEK2. These finding together with the concerning silent carriage of vanA gene among VSSA and VISA (5%) may underly hidden and uninvestigated factors contributing to vancomycin treatment failure that warrant cautious vancomycin prescription.

PBP4 is required for serum-induced cell wall thickening and antibiotic tolerance in Staphylococcus aureus.

The bacterial pathogen Staphylococcus aureus responds to the host environment by synthesizing a thick peptidoglycan cell wall, which protects the bacterium from membrane-targeting antimicrobials and the immune response. However, the proteins required for this response were previously unknown. Here, we demonstrate by three independent approaches that the penicillin-binding protein PBP4 is crucial for serum-induced cell wall thickening. First, mutants lacking various non-essential cell wall synthesis enzymes were tested, revealing that a mutant lacking pbp4 was unable to generate a thick cell wall in serum. This resulted in reduced serum-induced tolerance of the pbp4 mutant toward the last resort antibiotic daptomycin relative to wild-type cells. Second, we found that serum-induced cell wall thickening occurred in each of a panel of 134 clinical bacteremia isolates, except for one strain with a naturally occurring mutation that results in an S140R substitution in the active site of PBP4. Finally, inhibition of PBP4 with cefoxitin prevented serum-induced cell wall thickening and the resulting antibiotic tolerance in the USA300 strain and clinical MRSA isolates. Together, this provides a rationale for combining daptomycin with cefoxitin, a PBP4 inhibitor, to potentially improve treatment outcomes for patients with invasive MRSA infections.

Genomic characterization of MRSA recovered from people with cystic fibrosis during two Spanish multicentre studies (2013 and 2021).

Chronic bronchopulmonary infection due to MRSA in people with cystic fibrosis (pwCF) has been associated with accelerated decline in lung function, increased hospitalizations and increased mortality. We studied microbiological and genomic characteristics of MRSA isolates recovered from pwCF in two Spanish multicentre studies (2013, 2021). Antimicrobial susceptibility was performed. WGS was carried out to determine population structure [MLST, spa-typing, staphylococcal cassette chromosome mec (SCCmec)], resistome and virulome. Clinical charts of MRSA-infected and MRSA-non-infected pwCF were also reviewed. MRSA infection prevalence decreased between 2013 (29/341, 8.5%) and 2021 (21/326, 6.4%) (P = 0.378). Differences in lung function were observed between infected and non-infected patients (P < 0.005). A higher prevalence of hospital-acquired (HA) clones was found compared with community-acquired (CA) clones (2013: 67% versus 33%; and 2021: 71% versus 29%). Overall, we noted clustering of isolates based on year of sampling, type of acquisition and clonal complex (CC). HA-MRSA population was dominated by CC5, with ST125-MRSA-IVc-t067 the most prevalent lineage (37%). A higher clonal diversity was detected among CA-MRSA. One Panton-Valentine leucocidin (PVL)-positive strain (ST8-MRSA-IV) and three strains of porcine origin (two ST398-MRSA-V-t011, one ST398-MRSA-V-t8567) were found. Additionally, acquired resistance genes (n = 24) were detected, including the cfr gene conferring linezolid resistance. A higher gentamicin resistance was found in 2021 (42%) compared with 2013 (7%) (P = 0.046), associated with the aac(6')-aph(2″) gene. Despite a decrease in MRSA prevalence, we showed its potential impact on CF severity and progression. Moreover, we observed great genotypic and phenotypic diversity in MRSA isolates from pwCF as well as an MDR trait.

Clinical, demographic characteristics and antimicrobial resistance profile of Staphylococcus aureus isolated in clinical samples from pediatric patients in a tertiary hospital in Rio de Janeiro: 7-year longitudinal study.

In the pediatric population, Staphylococcus aureus infections are responsible for increased morbidity and mortality, length of hospitalization and the cost of inpatient treatment. The aim of this study is to describe the antimicrobial resistance profile of S. aureus isolated in clinical specimens from pediatric patients admitted to a tertiary hospital in Rio de Janeiro, Brazil. Culture reports and medical records of hospitalized patients under 18 years of age with S. aureus infections between January 2015 and December 2022 were retrospectively analyzed. Information was collected on recent antibiotic use, previous hospital admission, inpatient unit, clinical specimen, time of infection (community or nosocomial), classification according to susceptibility to methicillin (methicillin sensitive - MSSA or methicillin resistant - MRSA) and sensitivity to other antimicrobials. We analyzed the distribution of the sensitivity profile of S. aureus infections over the 7 years evaluated in the study. Were included 255 unique clinical episodes, among which the frequencies of MSSA and MRSA were 164 (64%) and 91 (36%), respectively. Over the 7 years evaluated, there was stability in the prevalence percentage, with a predominance of MSSA in the range of 60 to 73.3%, except in 2020, when there was a drop in the prevalence of MSSA (from 73.3% in 2019 to 52.5%) with an increase in MRSA (from 26.7% in 2019 to 47.5%). Ninety-seven (38%) infections were community-acquired and 158 (62%) were healthcare-associated. The main clinical specimens collected were blood cultures (35.2%) and wound secretions (17%). The MRSA isolates presented percentages of sensitivity to trimethoprim-sulfamethoxazole from 90.4 to 100%, and to clindamycin from 77 to 89.8% in MRSA healthcare associated and MRSA community respectively. There was a constant predominance in the prevalence of MSSA with percentage values ​​maintained from 2015 to 2022, except in 2020, in which there was a specific drop in the prevalence of MSSA with an increase in MRSA. MSSA infections are still predominant in the pediatric population, but MRSA rates also present significant values, including in community infections, and should be considered in initial empiric therapy.

EVALUATION OF MINIMAL INHIBITORY CONCENTRATIONS OF CEFTAROLINE, TEICOPLANIN AND DAPTOMYCIN FOR TREATMENT OF METHICILLIN RESISTANT STAPHYLOCOCCUS AUREUS IN A TERTIARY CARE SETTING

Objective: To evaluate Minimal Inhibitory Concentrations of ceftaroline, teicoplanin &amp; daptomycin for treatment of methicillinresistant Staphylococcus aureus in a tertiary care setting.Study Design: Experimental study.Place and Duration of Study: Department of Pathology, Microbiology Laboratory from Nov 2021 to Oct 2022.Methodology: All the isolated Staph. aureus was processed and identified by colony morphology on blood agar, gram stain,and biochemical tests i.e., catalase, coagulase and DNAase test. Minimal Inhibitory Concentration was evaluated using Estrips for ceftaroline, teicoplanin &amp; daptomycin for all the MRSA strains during the study period.Results: A total of 924 S.aureus strains were processed, and 270 (29.22%) MRSA were recovered during the study period. Thehighest percentage 50 was observed in sputum (n=2), followed by 41.66% in endobronchial washing (n=10), pus 160 (31.25%),tissue 30 (31.25%), pus swab 50 (29.76%), high vaginal swab 2 (25%), and least in blood 16 (14.54%). MICs for all the MRSAisolates to teicoplanin were in susceptible range (≤8µg/ml). MIC of 22 (8.14%) and 14 (5.18%) MRSA isolates for Ceftarolineand daptomycin were in susceptible dose-dependent (SDD=2-4µg/ml) range.Conclusion: The diagnostic modality, antimicrobial susceptibility testing, and MIC determination were found to be the bestapproach for adequate management of MRSA.

Detection Staphylococcus aureus contaminated some door handles and table surfaces and their sensitive to antibiotics

The current study's objective was to identify and isolate Staphylococcus spp. germs from a few of Omar Al-Mukhtar University's faculty laboratories. It is regarded as the first investigation carried out at Omar Al-Mukhtar University to assess the level of Staphylococcal bacterial contamination of door handles and table surfaces inside the laboratories. 33 isolates from the College of Science's Botany Department were used in the study, which took place in the department's laboratories during the fall semester of the academic year (2022). After evaluating the expanding colonies and using morphological inspections and biochemical tests to diagnose the isolates, it was showed that 90.9% of the samples from the Botany Department were Staphylococcus and that the percentage of S. aureus reached 36.7% of isolates of Staphylococcus. A biofilm-forming capacity was demonstrated by 80% of the isolated bacteria, of which 29% were S. aureus. In order to ascertain the effectiveness of the antibiotics and which ones the bacteria are resistant to, the sensitivity of thirty S. aureus isolates to hospital-grade antibiotics against infection was tested. The findings revealed a high level of resistance to the majority of antibiotics and a definite resistance to gentamicin. Methicillin-resistant MRSA isolates made up 73.3% of the isolates, whereas vancomycin-resistant VRSA isolates made up 70%.

Identification of Iles Gene Encoding Low-Level Mupirocin Resistance in Clinical Isolates of MRSA And MSSA

Identification of Iles Gene Encoding Low-Level Mupirocin Resistance in Clinical Isolates of MRSA And MSSA

The circulation of methicillin-resistant Staphylococcus aureus between humans, horses and the environment at the equine clinic.

We performed a retrospective analysis of MRSA isolates collected at the university equine clinic including clinical isolates from 2008 to 2021 and screening environmental, equine and personnel isolates from 2016. Screening and clinical samples were cultured on Brilliance MRSA 2 and Columbia agar (Oxoid), respectively, with enrichment for environmental samples. Antimicrobial susceptibility was assessed by disc diffusion. All the isolates were characterized by spa typing. Eighteen selected isolates were subjected to WGS with subsequent wgMLST clonal analysis. Among 75 MRSA isolates, five spa types were identified, the majority (n = 67; 89.33%) was t011. All isolates were resistant to cefoxitin and ampicillin and carried the mecA gene. In addition, the isolates were resistant to tetracycline (n = 74; 98.67%), gentamicin (n = 70; 93.33%), enrofloxacin (n = 54; 72.00%), sulfamethoxazole-trimethoprim (n = 5; 6.67%) and lincomycin (n = 3; 4.00%) with corresponding genetic markers for the resistance detected in the sequenced isolates. All 18 sequenced isolates belonged to ST398, 16 carried SCCmec type IVa and two carried SCCmec type Vc (5C2&5). Further, isolates carried aur, hlgA, hlgB and hlgC virulence genes, and five isolates carried sak and scn genes, which are part of the immune evasion cluster. Close genetic relatedness was found between isolates from the staff of the clinic and clinical samples of horses. Repeated introduction and long-term persistence of the equine LA-MRSA subclone (ST398-MRSA-IVa/Vc(5C2&5), t011) among the infected horses at the equine clinic with the colonization of personnel, and the environment contamination that might contribute to transmission were observed.

Effective biofilm eradication in MRSA isolates with aminoglycoside-modifying enzyme genes using high-concentration and prolonged gentamicin treatment.

Our analysis of 101 MRSA clinical isolates has provided valuable insights that could enhance treatment selection for biofilm infections in orthopedics. We found that high concentrations of gentamicin were effective against MRSA biofilms, and even prolonged exposure to concentrations lower than the minimum biofilm eradication concentration (MBEC) value could eliminate biofilms. The presence of the aac(6')-aph(2″) gene, an aminoglycoside resistance gene, was found to correlate with the minimum inhibitory concentration (MIC) and MBEC values of gentamicin, providing a potential predictive tool for treatment susceptibility. These results suggest that extended high concentrations of local gentamicin treatment could effectively eliminate MRSA biofilms in orthopedic infections. Furthermore, testing for gentamicin MIC or the possession of the aac(6')-aph(2″) gene could help select treatment, including topical gentamicin administration and surgical debridement.

Phenotypic and genotypic characterization of methicillin resistant Staphylococcus aureus associated with pyogenic infections.

Staphylococcal infections are one of the major infectious diseases affecting globally in spite of advances in development of antimicrobial agents. Knowledge and awareness about the local pattern and prevalence of MRSA infections plays a key role in treatment. The aim of this study was to identify MRSA strains by phenotypic and genotypic methods and to analyze the antibiotic susceptibility pattern of MRSA strains from patients attending a tertiary care hospital. This study was conducted over a period of 1 year, where 296 isolates of Staphylococcus aureus were isolated from various clinical specimens. The isolated strains were examined for antibiotic susceptibility by the modified Kirby Bauer disc diffusion method. Methicillin resistance was detected by cefoxitin disk diffusion test. A total of 104 isolates were found to be MRSA and 192 were found to be MSSA. Among the 104 MRSA isolates, 10 strains that were multidrug resistant were subjected to 16S rRNA gene sequencing analysis. All the 10 strains had a 99% match with S. aureus strains that were responsible for causing some serious biofilm mediated clinical manifestations like cystic fibrosis and device mediated infections. The biofilms were quantified using crystal violet staining and their ability to produce biofilms was analyzed using scanning electron microscopy and matched with the Genbank. Hence these phylogenetic analysis aid in treating the patients and combating resistance to antibiotics.

High hemolytic activity of the Staphylococcus aureus spa t1081 among clonal complex 45 in Taiwan

BackgroundMethicillin-resistant Staphylococcus aureus (MRSA) sequence type (ST) 45 was first reported in Taiwan in 2006. Since then, the prevalence of ST45 MRSA in clinical isolates has increased. This study was carried out to understand the changes in the proportions, evolutionary relationships, and infection advantages of ST45 and its related clones. Materials and methods: S. aureus including MRSA and MSSA (methicillin-sensitive S. aureus), and clonal complex (CC) 45 blood isolates were collected in 2000, 2005, and from January 2010 to August 2014. Molecular typing, multiple-locus variable-number tandem repeat analysis (MLVA) and single nucleotide polymorphism (SNP)-based phylogenetic analysis were performed. Fitness and virulence analyses were used to understand the infection advantages of the isolates. ResultsAmong the 67 CC45 isolates, only MSSA ST508 isolates were found in 2000 and 2005. Since 2010, the prevalence of MRSA has increased, t1081/ST45 has become dominant, and MRSA ST508 has been found. Phylogenetic analysis indicated that most of the ST45 isolates were located in a cluster distinct from those of ST508 and ST929. However, the t026 isolates clustered with the ST508 isolates rather than with the other ST45 isolates. Moreover, fitness and virulence analyses revealed that the t1081 isolates had higher hemolytic activity than the t026 and ST508 isolates did. ConclusionOur findings indicated that the increased prevalence of ST45 MRSA isolates from blood cultures in Taiwan was due to the t1081 isolates, and their high hemolytic activity may provide an infection advantage.

Staphylococcus aureus: changes in antimicrobial sensitivity profile and its relationship with SCCmec among clinical isolates

Background and Objectives: Staphylococcus aureus is a pathogen of great clinical relevance, especially those resistant to methicillin, called MRSA. Over the years, S. aureus antimicrobial resistance patterns have changed. Understanding such changes is essential to update protocols and propose efficient therapeutic approaches. This study aimed to characterize the temporal distribution of S. aureus antimicrobial resistance in patients admitted to the hospital as well as to assess its relationship with SCCmec typing. Methods: a total of 9,949 cultures of clinical materials were analyzed, between January 2000 and October 2019, from patients admitted to a university hospital in southern Brazil. All isolates had their identification and antimicrobial sensitivity profile analyzed using manual and automated techniques. Furthermore, 86 isolates were selected for mecA gene research and SCCmec typing using conventional and multiplex PCR techniques, respectively. Results: when assessing the temporal distribution of S. aureus over 20 years, it was possible to observe a drop in the proportion of MRSA compared to methicillin-sensitive S. aureus (MSSA). Between 2000 and 2002, the frequency of MRSA was 58.5%, whereas that of MSSA was 36.7%. However, from 2003 onwards, there was a reversal of these percentages. At the end of the analyzed period, 55.2% of infections were caused by MSSA, whereas 36.2% contained MRSA isolates. Furthermore, in the period analyzed, the highest prevalence was of SCCmectype II. Conclusion: these data suggest an epidemiological change in S. aureus from clinical materials, with a change in the prevalent type of SCCmec and changes in the antimicrobial sensitivity profile exhibited by the isolates. Such facts must be considered by the clinical staff with a focus on effective patient management, the choice of appropriate antimicrobial therapy so that effective infection control measures are implemented.

Iron oxide nanoparticles of Cystoseira sp. Sugar alcohol treat MRSA and thyroid gland cancer

PurposeMethicillin-resistant Staphylococcus aureus (MRSA) infections are emerging as a cause of suppurative thyroiditis. The resistance to several antibiotics and finding treatment has grown more difficult. Hence, the purpose of this study was to examine biosynthesized iron oxide nanostructures’ antimicrobial activity as well as their cytotoxicity on normal and thyroid cancer cells. MethodsBy using the sugar alcohols of Cystoseira sp., the authors synthesized the advanced biosynthesis of iron oxide nanoparticles (COINs). An agar-well diffusion method and a broth dilution method were used to investigate COINs’ antimicrobial activity against MRSA isolates. However, their cytotoxicity against normal and thyroid cancer cell lines was determined by the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. ResultsA GC–MS analysis of the dried Cystoseira sp. extract revealed a high percentage of D-mannitol, which is essential for the synthesis of spherical nanoparticles with a mean average size of 5.8 ± 0.8 nm. The COINs showed a higher inhibition zone (9–15 mm) for 66.6 % of MRSA isolates, and the MIC of COINs was 256 μg/ml. The cell wall of these bacteria inhabits the absorption of COINs. As a result, a large concentration of COINs is required to restrict bacterial growth. Moreover, COINs have cytotoxicity on thyroid cancer cell proliferation and normal thyroid cell lines at IC50s of 1.71 ± 0.1 and 25.9 ± 1.6 μg/ml, respectively. This can be due to the negative charge of sugar alcohols, which affect protein absorption and subsequent biological behaviors. ConclusionThe promising findings of this study are in favor of the creation of very small iron oxide nanostructures for therapy.

Temporal trends of skin and soft tissue infections caused by methicillin-resistant Staphylococcus aureus in Gabon

BackgroundMethicillin-resistant Staphylococcus aureus (MRSA) is one of the leading causes of mortality due to bacterial antimicrobial resistance. While S. aureus is common in skin and soft tissue infections (SSTI) in Africa, data on MRSA rates are scarce and reports vary widely across the continent (5%-80%). In this study, we describe the proportion of MRSA causing SSTI in Lambaréné, Gabon, over an 11-year period.MethodsWe retrospectively analyzed data from 953 bacterial specimens collected from inpatients and outpatients with SSTI at the Albert Schweitzer Hospital, Lambaréné, Gabon, between 2009 and 2019. We determined temporal changes in the prevalence of MRSA and identified risk factors for SSTI with MRSA.Results68% of all specimens with bacterial growth yielded S. aureus (n = 499/731), of which 7% (36/497) with antimicrobial susceptibility testing were identified as MRSA. Age above 18 years, admission to the surgical ward, and deep-seated infections were significantly associated with MRSA as the causative agent. After an initial decline from 7% in 2009, there was a marked increase in the proportion of MRSA among all S. aureus from SSTI from 3 to 20% between 2012 and 2019. The resistance rate to erythromycin was significantly higher in MRSA than in methicillin-susceptible S. aureus (73% vs. 10%), and clindamycin resistance was detected exclusively in MRSA isolates (8%).ConclusionThe increasing proportion of MRSA causing SSTI over the 11-year period contrasts with many European countries where MRSA is on decline. Continuous surveillance of MRSA lineages in the hospital and community along with antibiotic stewardship programs could address the increasing trend of MRSA.

Efficacy of Novel Antimicrobial Therapies for Treating Staphylococcus Infections in Wistar Rats

The novel semisynthetic lipoglycopeptide dalbavancin has enhanced antibacterial action against a wide range of gram-positive bacteria. This study was conducted to evaluate the efficacy of dalbavancin in treating Staphylococcus Infections in Wistar Rats. Anaesthetized wistar rats had a Kirschner-wire and a clinical MRSA isolate placed into their proximal tibia. Twenty animals were given dalbavancin (20 mg/kg loading dose) throughout the course of four weeks after infection, or they were left untreated. Microbiological analysis was performed on tibial bones and Kirschner-wires twenty-four hours after the last treatment dosage. As opposed to control group, dalbavancin treated group showed improvement in quantitative bacterial cultures of osseous tissue. After four weeks of treatment with dalbavancin, there was no sign of an induced glycopeptide-/lipoglycopeptide-resistant strain. In conclusion, in a rat study, dalbavancin effectively treated experimental implant-related MRSA osteomyelitis. The therapeutic effectiveness of dalbavancin in treating S. aureus infections needs more investigation; ideally, it should be studied in conjunction with biofilm active medicines.

Investigation of SCCmec types using the real time PCR method in cefoxitin-resistant Staphylococcus aureus isolates

BackgroundMethicillin-resistant Staphylococcus aureus (MRSA) is an important pathogen that can cause many community and hospital-acquired infections. This study was conducted to investigate the SCCmec gene types responsible for methicillin resistance in MRSA isolates isolated from hospitalised patients. Material and methodsMRSA isolates isolated from samples sent from various clinics to Gaziantep University Hospital Microbiology Laboratory between March 2021–January 2022 were included in the study. Bacteria were identified using by VITEK 2 automated system. Cefoxitin (FOX) resistance was determined by the disc diffusion method according to EUCAST standards. Cefoxitin resistance was confirmed by the Penicillin Binding Protein 2′ latex agglutination test. Types of mecA, mecC, coa, nuc, Panton Valentin Leukocidin (PVL), ccrC2, class A mec, SCCmec types in isolates detected as MRSA were investigated by real-time PCR. ResultsIn this study, 116 isolates meeting the study criteria were examined. By detecting the nuc and coa genes in all isolates by PCR, the phenotypic identification of S.aureus was confirmed. While the mecA gene was detected in all MRSA isolates, no mecC gene was detected in any isolates. Detected SCCmec types were as follows; SCCmec Type 1 (2.6%), Type II (28.4%), Type III (12.9%), Type IVa (11.2%), Type IVb (3.4%), Type IVc (3.4%), Type IVg (12.1%), Type V (0.9%), Type VII (4.3%), Type VIII (18.1%), Type IX (0.9%), Type XII (1.7%). On the other hand, SCCmec Type VI, X, XI and XIII were not found in any isolate. It was determined that four of the MRSA isolates (3.4%) carried the PVL gene that two (50%) of these were found in SCCmec Type VIII. ConclusionMonitoring of FOX resistance is an effective and safe method for determination of MRSA isolates. The change in the mec gene causes resistance, which should be monitored regularly with molecular methods. Our study is the first study in Turkey.

Chromosomal and plasmid localization of ileS2 in high-level mupirocin-resistant Staphylococcus pseudintermedius and Staphylococcus aureus isolated from canine and feline origins.

To characterize the mobile genetic elements and genetic localization of ileS2 in high-level mupirocin-resistant (Hi-MupR) methicillin-resistant Staphylococcus pseudintermedius (MRSP) and MRSA isolates recovered from canine and feline clinical samples. The identification of bacterial species and presence of mecA and ileS2 genes in MRSP and MRSA isolates were performed using MALDI-TOF MS and PCR, respectively. Antimicrobial resistance (AMR) phenotypes were determined by broth microdilution assays. The genome characteristics, ileS2-containing elements and staphylococcal cassette chromosome mec (SCCmec) were illustrated using complete circular genomes obtained from hybrid assembly of Illumina short-reads and Oxford Nanopore Technologies long-reads. These were analysed through phylogenetic and bioinformatics approaches. A total of 18 MRSP clinical isolates and four MRSA clinical isolates exhibited the Hi-MupR phenotype and carried multiple AMR genes, including mecA and ileS2 genes. MRSP ST182-SCCmec V (n = 6) and ST282-ΨSCCmec57395-t10 (n = 4) contained the ileS2 transposable unit associated with IS257 on the chromosome. Three MRSA ST398-SCCmec V-t034/t4652 isolates carried ∼42 kb pSK41-like ileS2 plasmids, whereas similar ileS2 plasmids lacking tra genes were found in MRSP ST282-ΨSCCmec57395-t72/t21 isolates. Furthermore, a new group of ileS2 plasmids, carried by MRSP ST45-ΨSCCmec57395, ST433-ΨSCCmecKW21-t05 and ST2165-SCCmec IV-t06, and by one MRSA ST398-SCCmec V-t034 strain, shared the plasmid backbone with the cfr/fexA-carrying plasmid pM084526_1 in MRSA ST398. This study provides the first evidence of ileS2 integration into the S. pseudintermedius chromosome, which is a rare occurrence in staphylococcal species, and plasmids played a pivotal role in dissemination of ileS2 in both staphylococcal species.

In vitro activity of ozenoxacin against Staphylococcus aureus and Streptococcus pyogenes clinical isolates recovered in a worldwide multicentre study (2020-2022).

We performed a multicentre study (2020-2022) to compare the in vitro activity of ozenoxacin and comparator agents against Staphylococcus aureus and Streptococcus pyogenes clinical isolates from skin and soft-tissue infections (SSTI). A total of 1725 isolates (1454 S. aureus and 271 S. pyogenes) were collected in 10 centres from eight countries between January 2020 and December 2022. Antimicrobial susceptibility testing was determined (microdilution-SENSITITRE). Results were interpreted following European Committee on Antimicrobial Susceptibility Testing (EUCAST) 2023 (clinical breakpoints, ECOFF) and CLSI criteria. Ozenoxacin exhibited high in vitro activity against S. aureus (MIC50/90 = 0.002/0.12 mg/L) and S. pyogenes (MIC50/90 = 0.015/0.03 mg/L), inhibiting 99% of the isolates at MIC ≤ 0.5 mg/L and at MIC ≤ 0.06, respectively. The most active comparators against S. aureus were retapamulin (MIC90 = 0.12 mg/L), fusidic acid (MIC90 = 0.25 mg/L) and mupirocin (MIC90 = 0.5 mg/L); and against S. pyogenes were retapamulin (MIC90 = 0.03 mg/L), clindamycin (MIC90 = 0.12 mg/L) and mupirocin (MIC90 = 0.25 mg/L). Ciprofloxacin and methicillin resistant rates for S. aureus were 31.3% (455/1454) and 41% (598/1454), respectively. Additionally, 62% (373/598) of the MRSA were also ciprofloxacin non-susceptible, whereas only 10% (23/271) of the MSSA were ciprofloxacin resistant. Ozenoxacin was more active against ciprofloxacin-susceptible S. aureus than against ciprofloxacin-resistant isolates, and showed a slightly higher MIC in MRSA isolates than in MSSA. However, ozenoxacin activity was comparable in both ciprofloxacin-resistant MSSA and MRSA subsets. On the other hand, ozenoxacin had similar activity in ciprofloxacin-susceptible and resistant S. pyogenes isolates. Ozenoxacin is a potent antimicrobial agent of topic use against Gram-positive bacteria causing SSTI, including MRSA isolates non-susceptible to ciprofloxacin.

Synanthropic rodents and shrews are reservoirs of zoonotic bacterial pathogens and act as sentinels for antimicrobial resistance spillover in the environment: A study from Puducherry, India

Antimicrobial resistance (AMR) is a global public health concern and needs to be monitored for control. In this study, synanthropic rodents trapped from humans and animal habitats in Puducherry, India, were screened as sentinels for bacterial pathogens of public health importance and antimicrobial resistance spillover. From the trapped rodents and shrews (n = 100) pathogens viz., Staphylococcus sp, E. coli and Salmonella sp were isolated from oropharyngeal and rectal swabs on Mannitol salt, Mac Conkey and Xylose lysine deoxycholate media respectively. The AMR genes in these isolates were screened by PCR. A total of 76, S. aureus and 19, Staphylococcus non aureus were isolated. E. coli was isolated in 89 samples and among the Salmonella sp (n = 59), 16, were S. enteritidis and 29, were S. typhimurium. A total of 46 MRSA isolates with mec A (n = 40) and mec C (n = 6) were detected. Also, 36.84% and 5.3% Staphylococcus non aureus isolates were tested to have mec A and mec C genes. AMR genes encoding ESBL [blaTEM in 21, blaSHV in 45 and blaCTX-M in 11] was tested positive in 77 E. coli isolates. Among, Salmonella isolates 44/45 were screened to have AMR genes [tet in 13, sul3 & sul4 in 20 and qnrA in 11]. Antibiotic sensitivity test confirmed the antimicrobial resistance. Isolation of pathogens of public health importance and demonstration of genetic elements conferring antimicrobial resistance in the synanthropic rodents confirms that they act as reservoirs and appropriate sentinels to monitor AMR spillover in the environment.