MRSA Isolates Research Articles

The Carriage of Methicillin-Resistant Staphylococcus aureus amongst Pregnant Women Attending Antenatal Clinic at a Tertiary Hospital, South-South Nigeria

Pregnant mothers are exposed to several infections because of their reduced immunity. Infections caused by Staphylococcus aureus among postpartum women and babies are increasing, and a rise in methicillin-resistant Staphylococcus aureus may have fueled this increase. The study was designed to investigate the carriage and resistance pattern of Methicillin-resistant Staphylococcus aureus among pregnant women attending the ante-natal clinic at the Niger Delta University Teaching Hospital, Okolobiri. Fifty urine samples were screened for Staphylococcus aureus on mannitol salt agar. Positive samples were then subjected to antibiotic sensitivity testing using the disc diffusion method, and resistance to Ceftriaxone was considered methicillin resistance. Results showed that 20 (40%) of the urine samples yielded growth of Staphylococcus aureus, 11 (73%) were resistant to Ceftriaxone, and over 70% of the MRSA isolates were multi-drug resistant. Methicillin-resistant Staphylococcus aureus colonisation in pregnant women has dire consequences, and a surveillance system for antimicrobial resistance surveillance system is recommended.

Characteristics of Virulent ST5-SCCmec II Methicillin-Resistant Staphylococcus aureus Prevalent in a Surgery Ward.

To investigate the transmission pathway of a MRSA prevalence in a pancreatic surgery ward in a Chinese teaching hospital. Molecular epidemiology investigations were carried out combined PFGE, MLST, SCCmec typing and whole-genome sequencing for 20 successive MRSA isolates (2 isolates from the ward environment). Resistance and virulence genes were detected using specific PCR. Bacterial identification and AST were performed using the Vitek 2 Compact System. Clinical data of enrolled cases were retrieved from electronic case records. From January 2020 to May 2020, successive isolated 20 MRSA strains were clarified to 2 PFGE patterns (A = 19, B = 1) in the ward. Both isolates from environment and patients belonged to sequence type ST5-SCCmec II-spa type t311. MRSA-related resistance genes mecA, blaZ, ermA, ant(4')-Ia and norA were found in each clone. All 20 isolates carried tst, hlg, hla, eta, eap, fnbA and seo virulence genes, other virulence genes such as sea, sec, seb, seg, sei, sem, sen, ebpS and fnbB were also found in partial stains. All patients had fever symptom, 27.8% were accompanied by diarrhea, 88.9% had undergone surgery or invasive procedures within 30 days. Finally, 94.4% of these patients recovered. This study confirmed a prevalence of ST5-MRSA-II-t311 clone in a surgery ward, indicated MRSA is a risk factor for post-surgery nosocomial infection and hand hygiene and environmental surveillance should not be ignored.

Pomegranate peel extract is an effective agent against MDR bacteria.

Multidrug-resistant (MDR) bacteria are one of the major public health threats facing humanity. Infections with MDR strains are difficult or impossible to treat with standard antibiotics leading to severe illnesses and even deaths. The spread of MDR bacteria has necessitated the search for alternative approaches that tackle MDR pathogens. Natural plants can be utilized as alternative therapeutic agents against the rise of MDR bacteria. In this study, we aimed to assess the antimicrobial activity of pomegranate peel extracts (PPE) against MDR clinical isolates. A total of 9 clinical isolates (8 MDR and 1 non-MDR clinical isolates) were collected and examined for their susceptibility to PPE. Using the zone of inhibition assay, 4 isolates (S. aureus, three MRSA isolates, Vancomycin-resistant Enterococci (VRE), and Acinetobacter baumannii) were sensitive to PPE. In Broth assay, 4 mg/ml PPE significantly reduced the growth (S. aureus, three MRSA isolates, Vancomycin-resistant Enterococci (VRE), and Acinetobacter baumannii), while 40 mg/ml PPE either significantly reduced or completely inhibited the growth of the isolates. The minimum bactericidal concentration (MBC) of PPE against S. aureus and MRSA-88 was 10 mg/ml. This study showed the potential of PPE as an alternative compound for treating infections caused by PPE-sensitive MDR bacteria.

In-vitro assessment of staphylococci biofilms formed under biologically-relevant conditions and correlation to the biofilm genotype

Staphylococci have been implicated in chronic device-related infections due to their ability to form resistant biofilms on implanted medical devices. For a long time, two different mechanisms of biofilm formation were known in Staphylococcus spp., the ica-dependent biofilms in MSSA and CoNS and the ica-independent biofilms in MRSA. Recently, a new fibrin-based biofilm phenotype was identified when S. aureus isolates were allowed to construct biofilms in biologically-relevant conditions using plasma-coated surfaces and RPMI-1640 for biofilm development (RPMI-1640/Pl). In this study, 140 staphylococci clinical isolates (91 MRSA, 27 MSSA and 22 CoNS) were tested for biofilm formation, biofilm formers were selected and used to scrutinize the ability of RPMI-1640/Pl to support staphylococci biofilm formation. Results showed that, in RPMI-1640/Pl, the biofilm formation abilities of MRSA and MSSA isolates were non-significantly different compared to those formed in TSB and BHI, (Kruskal Wallis test, P = 0.3275 and 0.466 for MRSA and MSSA isolates, respectively). However, a significantly different biofilm formation ability was observed regarding the tested CoNS isolates (ANOVA test, P = 0.0006). Furthermore, biofilm formation in RPMI-1640/Pl under different incubation conditions was tested, and among the tested conditions, 48h of static incubation showed significantly elevated biofilm for both MRSA and MSSA. Finally, PCR was used to detect genes implicated in biofilm formation, and the genotypes were correlated to the biofilm formation ability in different tested conditions. In contrast to ordinary media, biofilm formation by staphylococci in RPMI-1640/Pl was positively correlated to coa, fnbA, fnbB and clfB.

Genome Analysis of Methicillin-Resistant and Methicillin-Susceptible Staphylococcus aureus ST398 Strains Isolated from Patients with Invasive Infection.

Using genomic data, we determined the origin of MRSA ST398 isolates responsible for invasive infection in patients with no known livestock contact. We sequenced the genome of seven MSSA and four MRSA ST398 isolates from patients with invasive infections between 2013 and 2017, using the Illumina technique. Prophage-associated virulence genes and resistance genes were identified. To determine the origin of the isolates, their genome sequences were included in phylogenetic analysis also encompassing the ST398 genomes available on NCBI. All isolates carried the φSa3 prophage, but with variations in the immune evasion cluster: type C in MRSA isolates, and type B in MSSA isolates. All MSSA belonged to the spa type t1451. MRSA strains had the same SCCmec type IVa (2B) cassette and belonged to spa types t899, t4132, t1939 and t2922. All MRSA harbored the tetracycline resistance gene, tet(M). Phylogenetic analysis revealed that MSSA isolates belonged to a cluster of human-associated isolates, while MRSA isolates belonged to a cluster containing livestock-associated MRSA. We showed that the clinical isolates MRSA and MSSA ST398 have different origins. An acquisition of virulence genes by livestock-associated MRSA isolates allows them to induce an invasive infection in human.

Markers of epidemiological success of methicillin-resistant Staphylococcus aureus isolates in European populations

ObjectivesMethicillin-resistant Staphylococcus aureus (MRSA) infections impose a considerable burden on health systems, yet there is remarkable variation in the global incidence and epidemiology of MRSA. The MACOTRA consortium aimed to identify bacterial markers of epidemic success of MRSA isolates in Europe using a representative MRSA collection originating from France, the Netherlands and the United Kingdom. MethodsOperational definitions of success were defined in consortium meetings to compose a balanced strain collection of successful and sporadic MRSA isolates. Isolates were subjected to antimicrobial susceptibility testing and whole-genome sequencing; genes were identified and phylogenetic trees constructed. Markers of epidemiological success were identified using genome-based time-scaled haplotypic density analysis and linear regression. Antimicrobial usage data from ESAC-Net was compared with national MRSA incidence data. ResultsHeterogeneity of MRSA isolate collections across countries hampered the use of a unified operational definition of success; therefore, country-specific approaches were used to establish the MACOTRA strain collection. Phenotypic antimicrobial resistance varied within related MRSA populations and across countries. In time-scaled haplotypic density analysis, fluoroquinolone, macrolide and mupirocin resistance were associated with MRSA success, whereas gentamicin, rifampicin and trimethoprim resistance were associated with sporadicity. Usage of antimicrobials across 29 European countries varied substantially, and β-lactam, fluoroquinolone, macrolide and aminoglycoside use correlated with MRSA incidence. DiscussionOur results are the strongest yet to associate MRSA antibiotic resistance profiles and antibiotic usage with the incidence of infection and successful clonal spread, which varied by country. Harmonized isolate collection, typing, resistance profiling and alignment with antimicrobial usage over time will aid comparisons and further support country-specific interventions to reduce MRSA burden.

Evaluation of in vitro activity of ceftaroline against pathogens associated with community-acquired pneumonia: ATLAS program 2017–2019

Ceftaroline is an important therapeutic option for community-acquired pneumonia (CAP). Antimicrobial susceptibility to ceftaroline and other antimicrobial agents against Staphylococcus aureus, Streptococcus pneumoniae, and Haemophilusinfluenzae isolates collected worldwide from identified respiratory tract sources is reported by age groups (0-18, 19-65, and >65years). Antimicrobial susceptibility of isolates, collected as part of the ATLAS program (2017-2019), was performed per EUCAST/CLSI guidelines. S. aureus (N=7103; methicillin-susceptible S. aureus [MSSA]=4203; methicillin-resistant S. aureus [MRSA]=2791), S. pneumoniae (N=4823; EUCAST/CLSI, penicillin-intermediate S. pneumoniae [PISP]=1408/870; penicillin-resistant S. pneumoniae [PRSP]=455/993), and H. influenzae (N=3850; β-lactamase [βL]-negative=3097; βL-positive=753) isolates were collected from respiratory tract specimens. Susceptibility to ceftaroline was 89.08%-97.83% for S. aureus, 99.95%-100% for MSSA, and 78.07%-92.74% for MRSA isolates across age groups; S. aureus as well as MRSA isolates derived from the 0-18 years age group demonstrated the highest susceptibility rates to ceftaroline. Susceptibility to ceftaroline was 98.25%-99.77% for S.pneumoniae, 99.74%-100% for PISP, and 86.23%-99.04% for PRSP isolates across age groups. Across all age groups, susceptibility to ceftaroline was 89.53%-99.70% for H.influenzae, 93.02%-100% for βL-negative, and 77.78%-98.35% for βL-positive isolates. Irrespective of age, susceptibility to ceftaroline was high among the majority of S. aureus, S. pneumoniae, and H. influenzae isolates collected in this study.

An insight into whole genome sequencing data of methicillin-resistant Staphylococcus aureus circulating in a teaching hospital in North India

PurposeTo provide an insight into the Whole-genome sequencing (WGS) data of MRSA strains circulating in a teaching hospital in north India. MethodsAn exploratory study was conducted in which fifty non-repetitive MRSA isolates obtained from pus samples of inpatients from July 2018 to February 2019 were subjected to preliminary identification (ID) and antibiotic susceptibility testing (AST) at our centre. These isolates were later sent to Central Research Laboratory, India for further testing using the VITEK-2 compact system followed by WGS. Only eighteen isolates were eventually considered for final analysis and the rest (n ​= ​32) were excluded due to various technical reasons. ResultsThe WGS confirmed MRSA isolates predominantly belonged to CC22 (56.25%) and CC30 (31.25%). The CC22 MRSA strains carried SCCmec types IVa (77.8%) & IVc (22.2%) and belonged to spa types t005 (44.4%), t4584 (22.2%), t11808 (11.1%), t1328 (11.1%) and t309 (11.1%), respectively. The MRSA isolates of CC30 carried SCCmec types IVa (60%), IVg (20%) & V (20%) and belonged to spa types t021 (80%) & t2575 (20%), respectively. One MRSA isolate carried a novel SCCmec type V. The luk-PV and tsst-1 genes were present in 93.75% and 33.33% of MRSA isolates, respectively. The concordance between the phenotypic and genotypic AST results was 100% for Beta-lactams, Fluoroquinolones, Tetracyclines & Lipoglycopeptides, respectively. ConclusionsThrough this study, we intend to embark upon a relatively newer avenue of clinical-genomic surveillance of nosocomial bacterial isolates like MRSA, which would help us improve the existing infection control and antibiotic stewardship practices in our hospital.

Antibacterial, antibiofilm, and anti-quorum sensing activities of pyocyanin against methicillin-resistant Staphylococcus aureus: in vitro and in vivo study

BackgroundMethicillin-resistant Staphylococcus aureus (MRSA) infections are considered a major public health problem, as the treatment options are restricted. Biofilm formation and the quorum sensing (QS) system play a pivotal role in S. aureus pathogenicity. Hence, this study was performed to explore the antibacterial effect of pyocyanin (PCN) on MRSA as well as its effect on MRSA biofilm and QS.ResultsData revealed that PCN exhibited strong antibacterial activity against all test MRSA isolates (n = 30) with a MIC value equal to 8 µg/ml. About 88% of MRSA biofilms were eradicated by PCN treatment using the crystal violet assay. The disruption of MRSA biofilm was confirmed using confocal laser scanning microscopy, which showed a reduction in bacterial viability (approximately equal to 82%) and biofilm thickness (approximately equal to 60%). Additionally, the disruption of the formation of microcolonies and the disturbance of the connection between bacterial cells in the MRSA biofilm after PCN treatment were examined by scanning electron microscopy. The 1/2 and 1/4 MICs of PCN exerted promising anti-QS activity without affecting bacterial viability; Agr QS-dependent virulence factors (hemolysin, protease, and motility), and the expression of agrA gene, decreased after PCN treatment. The in silico analysis confirmed the binding of PCN to the AgrA protein active site, which blocked its action. The in vivo study using the rat wound infection model confirmed the ability of PCN to modulate the biofilm and QS of MRSA isolates.ConclusionThe extracted PCN seems to be a good candidate for treating MRSA infection through biofilm eradication and Agr QS inhibition.

Antimicrobial potential of Chlorella sorokiniana on MRSA – An in vitro study and an in silico analysis on ClpP protease

ObjectiveMethicillin-resistant Staphylococcus aureus (MRSA) strains are a leading cause of communicable disease in community and nosocomial settings. They are responsible for high morbidity and mortality. Researchers currently pursue novel antimicrobials from natural sources against non-traditional drug targets of staphylococci to ensure a pipeline of potent drugs, in the face of rising drug resistance. The focus of this study was to screen compounds from a freshwater isolate of Chlorella sorokiniana for anti-staphylococcal activity, using traditional microbiology, phytochemical analysis and bioinformatics approaches. MethodsChlorella sorokiniana methanol extract was investigated for its antimicrobial potential on Staphylococcus aureus strains (ATCC and MRSA isolates) by Kirby Bauer disc diffusion, broth microdilution, cell cytotoxicity and thin layer chromatography-bioautography (TLC-BA). Two antimicrobial TLC-BA antimicrobial fractions (A and B) were subject to gas chromatography mass spectrometry (GCMS). The structures of 9 compounds representing GCMS peaks were tested in silico, for their pharmacokinetic properties and binding energy efficiency with the target, using Molinspiration tool and Autodock 4.2. ResultsMean zone diameter of inhibition of growth by CSME (20 mg) was 21 mm, MIC/MBC was 0.31/2.5 mg/L. GCMS analysis of TLC fraction-A revealed 31 phytochemicals, of which 2-pentanone,4-hydroxy-4-methyl- had the highest area % (65.61) and TLC fraction-B revealed 4 peaks of which pentadecanoic acid and 1-(+)-ascorbic acid 2,6-dihexadecanoate had the highest area % (45.57, 48.09).In silico analysis of 9 peak compounds on the target of interest showed that compound 2: 2-pentanone,4-hydroxy-4-methyl- and compound 7: 1,2 – benzene dicarboxylic acid, mono (2- ethylhexyl) ester, satisfied Lipinski’s rule of 5, and displayed the least binding energies −6.93 and −5.74 with ClpP protease, thus holding pharmaceutical potential, and supporting further investment into in vitro and in vivo studies. ConclusionsC. sorokiniana, a less studied microalga thus offers a promising natural resource for anti-MRSA phytochemicals, capable of targeting ClpP1 protease.(290 words)

Methicillin-resistant and methicillin-sensitive Staphylococcus aureus in pork industry workers, Catalonia, Spain

BackgroundMethicillin-resistant S. aureus (MRSA) especially ST398, is a zoonotic agent. This study aimed to determine the prevalence of methicillin-susceptible S. aureus (MSSA) and MRSA among workers in the pork production chain. Methods659 workers associated with 123 pig farms, livestock transporters, one pig slaughterhouse, pork transporters and 23 pork butcheries were studied for S. aureus recovery, and all isolates were characterized (antibiotic resistance, MLST and spa-typing). ResultsThe prevalence of S. aureus was 35.5%, 75.6% of isolates being MRSA. The prevalence of MRSA was 68.7% (149/217) among pig farm, 33.9% (19/56) livestock transporters, 2.9% (9/306) slaughterhouse, 0% in pork transporters (0/36) and butchery workers (0/44). Of the 234 S. aureus-positive workers, 100% (149/149) of pig farm workers, 82.6% (19/23) of livestock transporters, and 16.4% (9/55) of slaughterhouse workers carried MRSA isolates (p < 0.001). Of the workers who had contact with live swine, 61.8% (178/288) were S. aureus-positive, MRSA being detected in 96.1% of cases (p < 0.001). The most frequent lineage among MRSA were: ST398 (97.7%; 173/177) and ST1 (1.7%; 3/177); and among MSSA were ST30 (19.2%; 11/57) and ST5 (10.5%; 6/57). The most frequent spa-types among MRSA were t011 (93.8%, 166/177) and t1451 (2.25%, 4/177), and among MSSA: t084 (10.5%, 6/57) and t021 (7.0%, 4/57). All MRSA isolates showed resistance to tetracycline, 92.7% to clindamycin, 81.9% to erythromycin and 40.1% to cotrimoxazole. ConclusionsPig industry workers having occupational contact with live animals present a high risk of colonization of MRSA, especially by MRSA-ST398. Prevention measures should be intensified in any employment sector involving live animals.

Antimicrobial Resistance Profile and Molecular Characterization of Staphylococcus aureus Isolated from Subclinical Mastitis of Dairy Cows in Mathura Region

Background: Subclinical mastitis is the most underrated yet economically important disease of livestock. It goes undetected by clinical examinations, making routine surveillance and monitoring necessary for its detection. Among causative agents, Staphylococcus aureus is the most crucial one. The present study determines the prevalence, antimicrobial resistance profile and molecular characterization of S. aureus from subclinical mastitis of cattle in the Mathura region. Methods: The present research was conducted during 2019-2021 and different gaushalas and dairies in and around the Mathura region were screened for mastitis by California mastitis test and somatic cell count. The samples positive were further tested by bacterial, biochemical and molecular tests along with an antimicrobial resistance profile. Result: Our research found a significant amount of S. aureus in subclinical samples with the presence of mecA gene suggesting MRSA. The public health importance of S. aureus and emerging resistance against antibiotics demands regular monitoring and effective use of antimicrobial agents against the MRSA isolates.

Antibacterial efficacy of Citrus hystrix (makrut lime) essential oil against clinical multidrug-resistant methicillin-resistant and methicillin-susceptible Staphylococcus aureus isolates

The increasing incidence of methicillin-resistant S. aureus is a major public health concern. Recently, the performance of Citrus hystrix essential oil (CHEO) has been shown to contain broad-spectrum antibacterial activity. Therefore, this study aims to determine the antibacterial activity of CHEO alone and in combination with gentamicin against panels of clinical isolates of methicillin-susceptible S. aureus (MSSA, n = 45) and methicillin-resistant S. aureus (MRSA, n = 40). Antibiotic susceptibility testing revealed multidrug-resistant (MDR) patterns among 3 MSSA isolates and 39 MRSA isolates, indicating that the clinical MRSA isolates were associated with MDR (p < 0.05). For the drug resistant isolates, resistance was observed toward most antibiotics, except for chloramphenicol, trimethoprim-sulfamethoxazole, linezolid, and vancomycin. Antibacterial screening by disk diffusion demonstrated that CHEO alone had certain antibacterial activity toward all MSSA isolates (IZD: 16.0 ± 4.7 mm) and MRSA isolates (IZD: 16.5 ± 4.2 mm) (p > 0.05). The MIC values of CHEO are 18.3 ± 6.1 mg/mL in MSSA isolates and 17.9 ± 6.9 mg/mL in MRSA isolates (p > 0.05). The antibacterial activity of CHEO demonstrated the bactericidal effect with MIC index 1.0–1.4. Time-killing kinetics revealed that CHEO at 1 × MIC completely killed MSSA and MRSA within 12 h. Moreover, the checkerboard titration demonstrated the synergistic and additive interactions of CHEO with gentamicin with FIC index 0.012–0.625. CHEO against human epidermal keratinocyte; HaCaT cell line demonstrated the IC50 value at 2.15 mg/mL. The use of CHEO as an alternative antibacterial agent would reduce the emergence of resistant bacteria, especially MDR MRSA.

Phenotypic and genotypic characterization of linezolid resistance and the effect of antibiotic combinations on methicillin-resistant Staphylococcus aureus clinical isolates

BackgroundMethicillin-Resistant Staphylococcus aureus (MRSA) causes life-threatening infections, with narrow therapeutic options including: vancomycin and linezolid. Accordingly, this study aimed to characterize phenotypically and genotypically, the most relevant means of linezolid resistance among some MRSA clinical isolates.MethodsA total of 159 methicillin-resistant clinical isolates were collected, of which 146 were indentified microscopically and biochemically as MRSA. Both biofilm formation and efflux pump activity were assessed for linezolid-resistant MRSA (LR-MRSA) using the microtiter plate and carbonyl cyanide 3-chlorophenylhydrazone (CCCP) methods, respectively. Linezolid resistance was further characterized by polymerase chain reaction (PCR) amplification and sequencing of domain V of 23 S rRNA; rplC; rplD;and rplV genes. Meanwhile, some resistance genes were investigated: cfr; cfr(B); optrA; msrA;mecA; and vanA genes. To combat LR-MRSA, the effect of combining linezolid with each of 6 different antimicrobials was investigated using the checkerboard assay.ResultsOut of the collected MRSA isolates (n = 146), 5.48% (n = 8) were LR-MRSA and 18.49% (n = 27) were vancomycin-resistant (VRSA). It is worth noting that all LR-MRSA isolates were also vancomycin-resistant. All LR-MRSA isolates were biofilm producers (r = 0.915, p = 0.001), while efflux pumps upregulation showed no significant contribution to development of resistance (t = 1.374, p = 0.212). Both mecA and vanA genes were detected in 92.45% (n = 147) and 6.92% (n = 11) of methicillin-resistant isolates, respectively. In LR-MRSA isolates, some 23 S rRNA domain V mutations were observed: A2338T and C2610G (in 5 isolates); T2504C and G2528C (in 2 isolates); and G2576T (in 1 isolate). Amino acids substitutions were detected: in L3 protein (rplC gene) of (3 isolates) and in L4 protein (rplD gene) of (4 isolates). In addition, cfr(B) gene was detected (in 3 isolates). In 5 isolates, synergism was recorded when linezolid was combined with chloramphenicol, erythromycin, or ciprofloxacin. Reversal of linezolid resistance was observed in some LR-MRSA isolates when linezolid was combined with gentamicin or vancomycin.ConclusionsLR-MRSA biofilm producers’ phenotypes evolved in the clinical settings in Egypt. Various antibiotic combinations with linezolid were evaluated in vitro and showed synergistic effects.

A HOSPITAL BASED PROSPECTIVE STUDY OF PREVALENCE OF METHICILLIN RESISTANT STAPHYLOCOCCUS AUREUS IN DERMATOLOGY INDOOR PATIENTS BY PHENOTYPIC METHOD

Introduction: Methicillin-Resitant Staphylococcus aureus is a cause of increased morbidity and mortality in debilitated and immunocompromised indoor patients. Aim: The aim of our study was to see the prevalence of Methicillin -Resistant Staphylococcus aureus infection in dermatology indoor patients by phenotypic method and elucidate its predisposing factors and antibiotic sensitivity pattern. Methods: This was a hospital based prospective study which included all dermatology indoor patients with primary and secondary bacterial infection. Results: The study enrolled 110 indoor patients with 57 males and 53 females. The mean age of the study was 39.23 years ranging between 2-90 years. Vesicobullous disorders were the commonest dermatoses with secondary infection. Diabetes mellitus was the most common comorbidity being present in 18 patients. S. aureus was the commonest bacterial isolate grown in culture in 66 patients, accounting for 60% of the total isolate. MRSA isolates accounted for 24.55% (27) of the total isolates. Majority of the MRSA patients (n=23, 85.19%) were having HAMRSA, while only 4 MRSA patients (n=4, 14.81%) were having CAMRSA. All MRSA isolates were sensitive to vancomycin and linezolid, while all the MRSA isolates were resistant to cefoxitin, oxacillin, cloxacillin, ampicillin and ciprofloxacillin. Conclusion: The prevalence of MRSA in our study was high. A high percentage of both MSSA and MRSA isolates were sensitive to gentamicin, which is a cheaper, effective and widely available antibiotic.

High Prevalence of Clonal Complex 398 Methicillin-Susceptible and -Resistant Staphylococcus aureus in Pig Farms: Clonal Lineages, Multiple Drug Resistance, and Occurrence of the Staphylococcal Cassette Chromosome mec IX

High prevalence of livestock-associated methicillin-susceptible and -resistant Staphylococcus aureus (LA-MSSA and LA-MRSA, respectively) in livestock farms, particularly pig farms, is an increasingly serious threat to food safety and public health. In this study, 173 S. aureus (84 MRSA and 89 MSSA) isolates from healthy pigs, farm environments, and farm workers in Korea were examined to determine the (1) genetic diversity of S. aureus isolates (sequence type [ST], spa, and agr types), (2) staphylococcal cassette chromosome mec (SCCmec) types of MRSA isolates, and (3) multidrug resistance (MDR) phenotypes of MRSA and MSSA isolates. Clonal complex 398 (CC398) genotypes of MRSA and MSSA isolates, particularly CC398-spa type t571-agr I lineages, displaying MDR phenotypes were highly prevalent in pig farms. High prevalence of CC398-t571 MRSA and MSSA was more frequently associated with weaning piglets and growing pigs. Moreover, the same clonal lineages of S. aureus isolates colonized both pigs and farm workers, suggesting the transmission of antimicrobial-resistant CC398 MRSA and MSSA between pigs and humans in the pig farms. Furthermore, two dominant SCCmec types, SCCmec V and SCCmec IX, were identified in CC398 MRSA isolates colonizing healthy pigs. To the best of our knowledge, this is the first report of a CC398 LA-MRSA isolate carrying SCCmec IX in Korea. Collectively, these results suggest widespread distribution of the CC398 lineage among MRSA and MSSA isolates in pigs, farm environments, and farm workers in Korea.

Prevalence of Methicillin-Resistant and Methicillin Sensitive Staphylococcus aureus Nasal Carriage and their Antibiotic Resistant Patterns in Kirkuk City, Iraq

The carriage of community-acquired methicillin-resistant S. aureus (CA-MRSA) has become a source of community-associated infections, particularly in the anterior nares of people worldwide. This study was aimed at determining the prevalence of community-acquired S. aureus (CA-SA) and CA-MRSA nasal carriage among healthy individuals of various ages in Kirkuk City and evaluating the susceptibility of isolates to various antibiotics. A total of 597 healthy individuals were recruited in the community between December 1, 2021, and December 30, 2022. Nasal swabs obtained from participants were taken to the laboratory, where bacteria were isolated and identified using phenotypic characteristics. The MRSA isolates were identified by applying the modified Kirby Bauer disc diffusion technique. The results showed that the prevalence of CA-SA and CA-MRSA nasal carriers was 16.6 and 4.5%, respectively. The average age of the participants was 33.2 years, with a male-to-female ratio of 1.1: 1. The highest resistance of the isolates was observed against oxacillin (27.3%), followed by penicillin G (24.3%), amoxicillin (15.2%), erythromycin (12.1%), and tetracycline (6.1%). There was a 9.1% resistance rate to clindamycin, rifampin, gentamycin, and ciprofloxacin. However, all CA-MRSA isolates were multi-drug resistant. However, all the isolates were sensitive (100 %) to vancomycin, linezolid, and mupirocin. The findings of the present study highlight the potential for CA-SA and CA-MRSA acquisition in this population, which may be related to antibiotic abuse or overuse as well as poor hygiene. To lessen the impact of community-associated strains of MRSA nasal carriage, this necessitates the probable need for infection prevention measures and adequate antibiotic therapy.

High Prevalence of Livestock-Associated Methicillin-Resistant Staphylococcus aureus in Hungarian Pig Farms and Genomic Evidence for the Spillover of the Pathogen to Humans

Livestock-Associated Methicillin-ResistantStaphylococcus aureus (LA-MRSA) strains of clonal complex (CC) 398 are widely disseminated in pigs and are considered emerging pathogens in human medicine. To investigate the prevalence, genetic characteristics, and zoonotic potential of the pathogen in pig production settings, dust samples were collected from 40 pig operations in Hungary, along with nasal swabs of attending veterinarians and other swine professionals (n = 27) in 2019. MRSA isolates were further characterized by performing whole-genome sequencing and susceptibility testing. The whole-genome sequences of 14 human-derived LA-MRSA clinical isolates from the same year were also included in the study. The proportion of positive farms was 83% (33/40), and 70% (19/27) of the swine professionals carried the pathogen. All but one MRSA strain belonged to CC398, including the human clinical isolates. The core genome multilocus sequence typing (cgMLST) analysis revealed clusters of closely-related isolates of both environmental and human origin with a pairwise allelic distance of ≤24, and both cgMLST and single nucleotide polymorphism (SNP) analyses suggest recent transmission events between the farm environment and humans. Four human clinical isolates harboured the immune-evasion gene cluster, of which one was considered to be closely related to farm isolates. Half of the swine-related strains showed decreased susceptibility to eight or more antimicrobials, and along with human isolates, they carried eight different types of multidrug-resistance genes, including cfr. The results showed a dramatic increase in the occurrence of LA-MRSA in the swine industry in Hungary, compared with the 2% prevalence reported by the European Food Safety Authority baseline study in 2008. The wide range of antimicrobial resistance of the strains, accompanied by the emergence of the pathogen in humans — both asymptomatic carriers and diseased — call for revision of the risk posed by LA-MRSA to the public health.

A Sequalae of Lineage Divergence in Staphylococcus aureus from Community-Acquired Patterns in Youth to Hospital-Associated Profiles in Seniors Implied Age-Specific Host-Selection from a Common Ancestor

The rapidly changing epidemiology of Staphylococcus aureus and evolution of strains with enhanced virulence is a significant issue in global healthcare. Hospital-associated methicillin-resistant S. aureus (HA-MRSA) lineages are being completely replaced by community-associated S. aureus (CA-MRSA) in many regions. Surveillance programs tracing the reservoirs and sources of infections are needed. Using molecular diagnostics, antibiograms, and patient demographics, we have examined the distributions of S. aureus in Ha'il hospitals. Out of 274 S. aureus isolates recovered from clinical specimens, 181 (66%, n = 181) were MRSA, some with HA-MRSA patterns across 26 antimicrobials with almost full resistances to all beta-lactams, while the majority were highly susceptible to all non-beta-lactams, indicating the CA-MRSA type. The rest of isolates (34%, n = 93) were methicillin-susceptible, penicillin-resistant MSSA lineages (90%). The MRSA in men was over 56% among total MRSA (n = 181) isolates and 37% of overall isolates (n = 102 of 274) compared to MSSA in total isolates (17.5%, n = 48), respectively. However, these were 28.4% (n = 78) and 12.4% (n = 34) for MRSA and MSSA infections in women, respectively. MRSA rates per age groups of 0-20, 21-50, and >50 years of age were 15% (n = 42), 17% (n = 48), and 32% (n = 89), respectively. However, MSSA in the same age groups were 13% (n = 35), 9% (n = 25), and 8% (n = 22). Interestingly, MRSA increased proportional to age, while MSSA concomitantly decreased, implying dominance of the latter ancestors early in life and then gradual replacement by MRSA. The dominance and seriousness of MRSA despite enormous efforts in place is potentially for the increased use of beta-lactams known to enhance virulence. The Intriguing prevalence of the CA-MRSA patterns in young otherwise healthy individuals replaced by MRSA later in seniors and the dominance of penicillin-resistant MSSA phenotypes imply three types of host- and age-specific evolutionary lineages. Thus, the decreasing MSSA trend by age with concomitant increase and sub-clonal differentiation into HA-MRSA in seniors and CA-MRSA in young and otherwise healthy patients strongly support the notion of subclinal emergences from a resident penicillin-resistant MSSA ancestor. Future vertical studies should focus on the surveillance of invasive CA-MRSA rates and phenotypes.

Genomic Evidence for Direct Transmission of mecC-MRSA between a Horse and Its Veterinarian

Methicillin-resistant Staphylococcus aureus bearing the mecC gene (mecC-MRSA) has been reported from animals and humans in recent years. This study describes the first mecC-MRSA isolates of human and equine origin in Hungary (two isolates from horses and one from a veterinarian, who treated one of the infected horses, but was asymptomatic). MRSA isolates were identified by cultivation and PCR detection of the species-specific spa gene and mecA/mecC methicillin resistance genes. The isolates were characterized by antibiotic susceptibility testing, MLST, spa, SCCmec typing, PFGE and whole genome sequencing (WGS). All three isolates belonged to the ST130-t843-SCCmec XI genotype, and carried the mecC and blaZ genes. Apart from beta-lactam drugs, they were sensitive to all tested antibiotics. The isolates of the infected horse and its veterinarian had the same PFGE pulsotype and showed only slight differences with WGS. Hence, this is the first description of direct transmission of a mecC-carrying MRSA between a horse and its veterinarian. The emergence of mecC in the country highlights the importance of the appropriate diagnostics in MRSA identification.