Inhibitory activities of vitamins K2 against clinical isolates of quinolone-resistant and methicillin-resistant Staphylococcus aureus (QR-MRSA) with different multi-locus sequence types (MLST), SCCmec, and spa types

BACKGROUND

The inhibitory activities of vitamins K₂ against clinical isolates of quinolone-resistant and methicillin-resistant Staphylococcus aureus (QR-MRSA) are unclear. The main aim is to better understand of inhibitory activities of vitamins K_2, multi-locus sequence typing (MLST), SCCmec, and spa typing in clinical isolates of QR-MRSA on those mutation and gene expressions.

MATERIALS AND METHODS

After collecting S. aureus clinical isolates and detecting QR-MRSA, the genes encoding norA, grlA, grlB, gyrA, and gyrB were sequenced. After treating isolates by vitamin K₂, isolates were prepared to measure norA, grlA, grlB, gyrA, and gyrB gene expression. The quantitative-real-time PCR was used to measure the expression of efflux pump genes.

RESULTS

QR-MRSA, MDR, and XDR strains were reported in 59.4%, 73.9%, and 37.6% of isolates, respectability. SCCmecIV (36.5%) and SCCmecV (26.8%) had the highest frequency. Thirty-nine spa types were identified, t021, t044, and t267 types most prevalent in QR-MRSA isolates. ST22 and ST30 dominated the invasive, drug-resistant isolates and QR-MRSA. In 24 h incubated isolates, the most noticeable change of gene expression with vitamin K₂ was that the norA, gyrA, and grlB genes were highly repressed. However, the down-regulation of grlA at 24 h after being treated by vitamin K₂ was more than another gene. Further, a significant decrease was observed in QR-MRSA-treated isolates compared to un-treated isolates. In other words, norA, grlA, grlB, gyrA, and gyrB genes were less suppressed by QR-MRSA (p ≤ 0.01, p ≤ 0.05).

CONCLUSION

Vitamin K₂ has significant inhibitory effects on the genes responsible for resistance to fluoroquinolone antibiotics. However, a subminimum inhibitory concentration (sub-MIC) level of vitamin K₂ was delayed but did not completely inhibit norA, grlA, grlB, gyrA, and gyrB genes in MRSA strains.

Nasal Carriage and Methicillin Resistance of Staphylococcus aureus among Schoolchildren in Sana'a City, Yemen

Background

Staphylococcus aureus (S. aureus) is a frequent cause of serious health problems with high morbidity and mortality. The risk of S. aureus infections is increased with the emergence of methicillin-resistant S. aureus (MRSA). This study aims to determine the nasal carriage rate of both S. aureus and MRSA among schoolchildren in Sana'a city.

Methods

This is a cross-sectional study conducted from January 2018 to May 2020. Five hundred and thirty-six students were enrolled. Their age ranged from 5 to 19 years with the mean age and standard deviation equal to 13.3 ± 3.5 years. Nasal swabs were collected from each student for culturing and methicillin susceptibility testing.

Results

Students with positive culture were 271 (51%) males and 265 (49%) females. S. aureus was isolated from 129 (24%) students whereas the overall prevalence of MRSA was 8 (1.5%). S. aureus was significantly recovered from students at the age group of 10–14 years (χ² = 7.02; p=0.03), females than males (OR = 1.96; χ² = 10.75; p=0.001), and students who were admitted into hospitals (OR = 1.6; χ² = 4.89; p=0.03). Nevertheless, there were no significant differences between MRSA carriage and students' age (χ² = 2.3; p=0.32), gender (OR = 1.02; χ² = 0.001; p=0.63), and hospital admission (OR = 1.4; χ² = 0.25; p=0.62).

Conclusions

The prevalence of MRSA is low among schoolchildren in Sana'a city. Age, gender, and previous hospital admission were statistically associated with nasal carriage of S. aureus but not MRSA nasal carriage.

First report of methicillin-resistant Staphylococcus aureus carrying the mecC gene in human samples from Iran: prevalence and molecular characteristics

There is a lack of information concerning mecC clinical methicillin-resistant Staphylococcus aureus (MRSA) strains throughout the world. In the present survey, 345 MRSA strains were characterized by antimicrobial susceptibility testing and staphylococcal cassette chromosome mec element (SCCmec) typing. mecC-positive MRSA isolates were characterized by study of biofilm formability, adhesion and virulence analysis, multilocus sequence typing, accessory gene regulator (agr) typing, S. aureus protein A locus (spa) typing and staphylocoagulase typing. The present study found ten SCCmec types, with the majority being SCCmec type III (38.3%). The presence of mecC was confirmed in three isolates from skin wounds (two isolates) and burn wounds (one isolate). All the mecC-positive isolates carried SCCmec XI and belonged to coa type III. Molecular typing showed that these isolates belonged to clonal complex/ST130-spa type t843-agr type III (two isolates) and clonal complex/ST599-spa type 5930-agr type I. The presence of SCCmec type IV confirms the hypothesis of extensive infiltration from the community to the hospital. Detection of MRSA isolates harbouring the mecC gene highlights the need to perform routine detection methods and molecular investigations in order to identify these emerging strains and limit their transfer in hospitals and communities.

The Occurrence of Type I, II, and III Integrons in Multi-drug Resistance and Methicillin-Resistant Staphylococcus aureus Isolates in Iran

Integrons are mobilizable platforms-DNA elements with impacts on moving antibiotic resistance genes among bacteria and capable of spreading multi-drug resistance (MDR) in pathogens. Methicillin-resistant Staphylococcus aureus (MRSA) strains are the main cause of community-acquired and nosocomial infections with high mortality and morbidity rates worldwide. This work is mainly aimed at calculating the frequency of Type I, II, and III integrons within multi-drug resistance and Methicillin-resistant S. aureus Isolates in Iran. In this cross-sectional study, 230 clinical isolates of S. aureus were gathered from patients of educational hospitals in the provinces of Iran. These isolates were verified utilizing particular biochemical examinations and then assessed for antibiotic susceptibility through disk diffusion technique and standard procedures were done. Genomic and plasmid DNA of all isolates were extracted using Extraction Kit and PCR assay was used for the detection of Type I, II and III integrons genes. Out of the 230 S. aureus isolates, 136 (59.1%) isolates were MRSA and 141 (61.3%) isolates exhibited the MDR pattern. PCR and sequencing showed that 57 (24.8%) of tested isolates carry Type I integron. Among the isolates investigated, MRSA and MDR isolates showed frequencies of 56.1% and 57.9%, respectively. Type II and III integrons were found in none of 230 isolates. The IntI I gene was present in approximately one-quarter of this study isolates. The great prevalence rate of MDR and MRSA isolates and concurrently the existence of Type I integron among those isolates have been considered an important concern in medical society.

Elimination of Staphylococcus aureus nasal carriage in intensive care patients lowers infection rates

This study surveys the clinical relevance of the nasal Staphylococcus aureus colonization status on intensive care unit (ICU)-acquired S. aureus infections and compares molecular characteristics of isolates from the nose and infectious sites. The 390 patients included comprised 278 non-carriers and 112 carriers. Among the carriers, 56 were decolonized with mupirocin. Decolonization was verified through a second (negative) culture. Spa typing and virulence gene profiling were performed for all isolates. Twenty six S. aureus infections were detected in the carriage group and 20 in the non-carriage group. Eighteen of these 26 (69.2%) infections were among carriers, and 8 of these 26 (30.8%) infections occurred among decolonized carriers (p = 0.02). Overall, 31/112 (27.7%) of the colonized patients and 25/46 (60.1%) of infection were due to methicillin-resistant S. aureus (MRSA). The highest frequency virulence genes were sea and hlg (both 100%) in nasal isolates and sea, hlg, fnb, and clf (100%) for infectious isolates. t030 was the most abundant spa type overall. S. aureus carriers were more likely to develop S. aureus infection compared with decolonized and non-carrying patients. The sources of ICU S. aureus infection appear to be exogenous mostly, and a predominant clone (spa type 030) plays an important role. We confirm that nasal mupirocin treatment prevents ICU infections even when there is an increased prevalence of nosocomial MRSA.

Phenotypic and Molecular Characterization of Methicillin-Resistant Staphylococcus aureus Clones Carrying the Panton-Valentine Leukocidin Genes Disseminating in Iranian Hospitals

The spread of Panton-Valentine leukocidin (PVL)-carrying Staphylococcus aureus strains in both hospital and the community is a significant worldwide problem. The aim of the study was to investigate the clonal dissemination pattern of PVL-producing S. aureus strains isolated from hospitalized patients in Tehran, Iran. In this cross-sectional study, 70 PVL-carrying S. aureus strains were recovered from 240 clinical specimens and characterized by antibiotic susceptibility testing, agr typing, SCCmec typing, spa typing, multilocus sequence typing, and virulence and adhesion gene profiling. All the PVL-carrying S. aureus strains were confirmed as methicillin-resistant S. aureus (MRSA) and recovered from wounds (48.6%), blood (25.7%), exudate/pus (11.4%), sputum (8.6%), and body fluid (5.7%) samples. Among the 70 PVL-carrying S. aureus strains tested, 38 (54.3%) were positive for ant (4')-Ia gene, 27 (38.6%) for aac (6')-Ie/aph (2″), 13 (18.6%) for msr(A), 13 (18.6%) for erm(C), 13 (18.6%) for tet(M), 11 (15.7%) for erm(A), 10(14.3%) for msr(B), 9 (12.9%) for aph (3')-IIIa, 5 (7.1%) for mupA, and 2 (2.9%) for erm(B) genes. Five clonal complexes (CC) and nine different clones were detected in this study. The most frequent CC was CC22 (ST22) (42.8%) followed by CC30 (ST30) (21.5%), CC8 (ST8) (17.2%), CC1 (ST772) (11.4%), and CC80 (ST80) (7.1%). In this study, ST22-SCCmec IV/t852 was the predominant PVL-positive MRSA clone (20%), followed by ST8-SCCmec IV/t008 (17.2%), ST30-SCCmec IV/t019 (12.9%), ST22-SCCmec IV/t790 (11.4%), ST22-SCCmec IV/t005 (11.4%), ST30-SCCmec IV/t021 (8.6%), ST80-SCCmec IV/t044 (7.1%), ST772-SCCmec V/t657 (7.1%), and ST772-SCCmec V/t10795 (4.3%). Diversity in clonal types of PVL-carrying MRSA strains in our study supports the need to perform a systematic surveillance of PVL-positive MRSA strains.