Epidermidis Isolates Research Articles

Identifying biofilm-forming strains of Staphylococcus epidermidis isolated from intravascular-catheterized patients by icaA and icaD genes

Abstract Staphylococcus epidermidis has gained a substantial importance in recent years because it is one of the main causative agents of nosocomial infections. It requires a predisposed host in order to switch from a normal inhabitant of the human skin to a pathogenic flora. This study aimed to use icaA/icaD genes as biomarkers in differentiating biofilm-forming S. epidermidis, obtained from patients with intravascular catheter (IVC) infections, from other saprophytic strains. Twenty isolates of S. epidermidis obtained from 100 cases of intravascular catheter infections were investigated for the presence of the intracellular adhesion icaA and icaD genes by polymerase chain reaction (PCR) and for phenotypic biofilm production by qualitative Congo red agar assay (CRA). Results: Nine (~45%) S. epidermidis isolates out of 20 isolates collected from IVC infections were positive for both CRA (produce black colonies) and icaA/icaD genes; while 11 (~55%) S. epidermidis isolates were negative for CRA and icaA/icaD genes. Detection of icaA/icaD gene is a reliable, efficient, and more rapid tool for characterizing biofilm-forming strains of S. epidermidis. Keywords: Staphylococcus epidermidis; icaA; icaD; biofilm

Evaluation of CHROMagar™ LIN-R for the Screening of Linezolid Resistant Staphylococci from Positive Blood Cultures and Nasal Swab Screening Samples.

The increasing number of nosocomial pathogens with resistances towards last resort antibiotics, like linezolid for gram positive bacteria, leads to a pressing need for screening and, consequently, suitable screening media. Some national guidelines on infection prevention (e.g., in Germany) have already recommended screening for linezolid-resistant bacteria, despite an accurate screening medium that was not available yet. In this study, we analyzed the performance and reliability of the first commercial chromogenic medium, CHOMagar™ LIN-R, for screening of linezolid-resistant gram-positive isolates. Thirty-four pure bacterial cultures, 18 positive blood cultures, and 358 nasal swab screening samples were tested. This medium efficiently detected linezolid-resistant S. epidermidis isolates from pure bacterial cultures and from positive blood cultures with a high sensitivity (100%) and specificity (100%). Among the 358 nasal swab screening samples prospectively tested, 10.9% were cultured with linezolid-resistant isolates (mostly S. epidermidis). Of note, slight growth was observed for 7.5% samples with linezolid-susceptible isolates of S. epidermidis (n = 1), S. aureus (n = 1), Enterococcus faecalis (n = 4), Lactobacillus spp. (n = 3), gram negatives (n = 18). Moreover, few Candida spp. also cultured on this medium (1.4%).

Staphylococcal Enterotoxin Genes in Coagulase-Negative Staphylococci-Stability, Expression, and Genomic Context.

In the current study, we screened a collection of coagulase-negative staphylococci (CoNS) isolates for orthologues of staphylococcal enterotoxins (SEs) involved in S. aureus-related staphylococcal food poisoning (SFP). The amplicons corresponding to SEs were detected in S. chromogenes, S. epidermidis, S. haemolyticus, S. borealis, S. pasteuri, S. saprophyticus, S. vitulinus, S. warneri, and S. xylosus. All amplicons were sequenced and identified as parts of known S. aureus or S. epidermidis SE genes. Quantitative real-time PCR allowed determining the relative copy number of each SE amplicon. A significant portion of the amplicons of the sea, seb, sec, and seh genes occurred at low copy numbers. Only the amplicons of the sec gene identified in three isolates of S. epidermidis displayed relative copy numbers comparable to sec in the reference enterotoxigenic S. aureus and S. epidermidis strains. Consecutive passages in microbiological media of selected CoNS isolates carrying low copy numbers of sea, seb, sec, and seh genes resulted in a decrease of gene copy number. S. epidermidis isolates harbored a high copy number of sec, which remained stable over the passages. We demonstrated that enterotoxin genes may occur at highly variable copy numbers in CoNS. However, we could identify enterotoxin genes only in whole-genome sequences of CoNS carrying them in a stable form at high copy numbers. Only those enterotoxins were expressed at the protein level. Our results indicate that PCR-based detection of enterotoxin genes in CoNS should always require an additional control, like analysis of their presence in the bacterial genome. We also demonstrate S. epidermidis as a CoNS species harboring SE genes in a stable form at a specific chromosome site and expressing them as a protein.

Complete sequences of epidermin and nukacin encoding plasmids from oral-derived Staphylococcus epidermidis and their antibacterial activity.

Staphylococcus epidermidis is a commensal bacterium in humans. To persist in the bacterial flora of the host, some bacteria produce antibacterial factors such as the antimicrobial peptides known as bacteriocins. In this study, we tried to isolate bacteriocin-producing S. epidermidis strains. Among 150 S. epidermidis isolates from the oral cavities of 287 volunteers, we detected two bacteriocin-producing strains, KSE56 and KSE650. Complete genome sequences of the two strains confirmed that they carried the epidermin-harboring plasmid pEpi56 and the nukacin IVK45-like-harboring plasmid pNuk650. The amino acid sequence of epidermin from KSE56 was identical to the previously reported sequence, but the epidermin synthesis-related genes were partially different. The prepeptide amino acid sequences of nukacin KSE650 and nukacin IVK45 showed one mismatch, but both mature peptides were entirely similar. pNuk650 was larger and had an additional seven ORFs compared to pIVK45. We then investigated the antibacterial activity of the two strains against several skin and oral bacteria and found their different activity patterns. In conclusion, we report the complete sequences of 2 plasmids coding for bacteriocins from S. epidermidis, which were partially different from those previously reported. Furthermore, this is the first report to show the complete sequence of an epidermin-carrying plasmid, pEpi56.

Rifamycin resistance, rpoB gene mutation and clinical outcomes of Staphylococcus species isolates from prosthetic joint infections in Republic of Korea

We conducted an in vitro investigation of the activity of rifamycins against planktonic and biofilm states of Staphylococcus aureus and Staphylococcus epidermidis isolates from patients with prosthetic joint infections (PJIs), characterised their rpoB gene mutations, and analysed the clinical outcomes of rifampicin-resistant isolates. A total of 110 staphylococcal isolates were collected from patients with PJI. Antimicrobials tested using the broth microdilution method included rifampicin, rifabutin, rifapentine and rifaximin. We evaluated rpoB gene mutations to identify rifampicin resistance mechanisms. Clinical outcomes were assessed in rifampicin-resistant isolates. The 110 staphylococcal isolates included 85 S. aureus (55% methicillin-resistant) and 25 S. epidermidis (100% methicillin-resistant). Seven S. aureus isolates and two S. epidermidis isolates were resistant to rifampicin [minimum inhibitory concentration (MIC) ≥2 μg/mL] and these isolates exhibited rpoB gene mutations. Among the 78 rifampicin-susceptible S. aureus isolates and 23 S. epidermidis isolates, 76 S. aureus isolates (97.4%) and all S. epidermidis isolates (100%) were highly susceptible (MIC ≤ 0.06 μg/mL) to other rifamycins. The minimum biofilm bactericidal concentrations for ≥50% of isolates (MBBC50) to rifampicin, rifabutin, rifapentine and rifaximin were 4, 1, 2 and 4 μg/mL for S. aureus and 1, 0.125, 0.25 and 0.5 μg/mL for S. epidermidis, respectively, among rifampicin-susceptible isolates. Among nine patients bearing rifampicin-resistant isolates, only three (33%) had successful outcomes. Rifamycins other than rifampicin show promising antistaphylococcal activity, including antibiofilm activity. Rifamycin-resistant staphylococci exhibit rpoB gene mutations.

Antibiotic Resistance and Pathogenomics of Staphylococci Circulating in Novosibirsk, Russia.

A total of 394 strains of staphylococci found in humans and pets in Novosibirsk, Siberian Russia, were characterized in terms of antibiotic resistance and corresponding genes. Two coagulase-positive and 17 coagulase-negative species were identified. The majority of isolates, with the exception of S. haemolyticus and hospital S. epidermidis isolates, were sensitive to most of the tested antibiotics, and isolates from pets displayed the lowest level of resistance. Nevertheless, methicillin-resistant (MRS) and/or multidrug-resistant (MDR) isolates were found in all prevailed species, including coagulase-negative. A set of genes corresponding to the detected resistance was identified: mecA (beta-lactam resistance), aac(6′)-Ie-aph(2″)-Ia, aph(3′)-IIIa, ant(4′)-Ia (aminoglycoside-modifying enzymes), ermA/ermC, and msrA (macrolide resistance). Complete genome analysis for ten MDR S. epidermidis and five MDR S. haemolyticus isolates revealed additional antibiotic resistance genes mphC, qacA/qacB, norA, dfrC/dfrG, lnuA, BseSR, and fosB. NorA, dfrC, and fosB were present in all S. epidermidis genomes, whereas mphC and msrA were identified in all S. haemolyticus ones. All investigated MDR S. epidermidis and four of five S. haemolyticus strains were moderate or strong biofilm producers, whereas multiple genes responsible for this function and for virulence and pathogenicity were identified mostly in S. epidermidis, but were less frequently represented in S. haemolyticus.

Heterogeneity of Staphylococcus epidermidis in prosthetic joint infections: time to reevaluate microbiological criteria?

Prosthetic joint infection (PJI) is a feared and challenging to diagnose complication after arthroplasty, with Staphylococcus epidermidis as the major pathogen. One important criteria to define PJI is the detection of phenotypically indistinguishable microorganisms with identical antibiotic susceptibility pattern in at least two different samples. However, owing to phenotypical variation within genetic clones and clonal variation within a phenotype, the criteria may be ambiguous. We investigated the extent of diversity among coagulase-negative staphylococci (CoNS) in PJI and characterised S. epidermidis isolates from PJI samples, specifically multiple S. epidermidis isolates identified in individual PJI patients. We performed a retrospective cohort study on 62 consecutive patients with PJI caused by CoNS from two hospitals in Northern Sweden. In 16/62 (26%) PJIs, multiple S. epidermidis isolates were available for whole-genome analyses. Hospital-adapted multidrug-resistant genetic clones of S. epidermidis were identified in samples from 40/62 (65%) of the patients using a combination of pulsed-field gel electrophoresis and multilocus sequence typing. Whole-genome sequencing showed the presence of multiple sequence types (STs) in 7/16 (44%) PJIs where multiple S. epidermidis isolates were available. Within-patient phenotypical variation in the antibiotic susceptibility and/or whole-genome antibiotic resistance gene content was frequent (11/16, 69%) among isolates with the same ST. The results highlight the ambiguity of S. epidermidis phenotypic characterisation as a diagnostic method in PJI and call for larger systematic studies for determining the frequency of CoNS diversity in PJIs, the implications of such diversity for microbiological diagnostics, and the therapeutic outcomes in patients.

205 The skin commensal Staphylococcus epidermidis induces inflammatory mediators in keratinocytes: Implications for atopic dermatitis

The chronic inflammatory skin disease atopic dermatitis (AD) is characterized by a dysbiosis of the microbiota. This is reflected by a decreased microbial diversity and the abundance of specific potential pathogenic strains such as Staphylococcus (S.) aureus. Staphylococcus (S.) epidermidis is an abundant member of the cutaneous microbiota and is considered generally as an apathogenic commensal that exhibits beneficial effects in AD, e.g. by controlling the growth of S. aureus. However, S. epidermidis is also frequently present in skin lesions of AD patients and a correlation between abundance of S. epidermidis and severity of AD has been reported. We therefore hypothesized that S. epidermidis may exhibit proinflammatory activities. To evaluate this hypothesis we stimulated cultured human keratinocytes and 3D skin models with different S. epidermidis isolates derived either from healthy skin or from lesional skin of AD patients. Real-time PCR and ELISA analyses revealed a significant induced expression of the AD-relevant cytokine thymic stromal lymphopoietin (TSLP) in keratinocytes and 3D skin after stimulation with S. epidermidis strains. S. epidermidis strains derived from lesional AD skin induced a higher TSLP expression than strains derived from healthy skin. Similar results were also obtained with the pro-inflammatory cytokines IL-17c and TNF-alpha. Both, S. epidermidis strains derived from healthy skin and strains derived from AD skin activated the inflammation-associated transcription factor NF-kappaB. Moreover, expression of the barrier-associated protein filaggrin was downregulated by S. epidermidis. Together, the observed S. epidermidis-mediated induction of proinflammatory mediators and downregulation of filaggrin in keratinocytes and 3D skin models may explain why AD patients carrying a high number of S. epidermidis are associated with a more severe inflamed disease state.

Bovine-associated non-aureus staphylococci suppress Staphylococcus aureus biofilm dispersal in vitro yet not through agr regulation

Biofilm formation is a significant virulence factor in Staphylococcus (S.) aureus strains causing subclinical mastitis in dairy cows. A role of environmental signals and communication systems in biofilm development, such as the agr system in S. aureus, is suggested. In the context of multispecies biofilm communities, the presence of non-aureus staphylococci (NAS) might influence S. aureus colonization of the bovine mammary gland, yet, such interspecies interactions have been poorly studied. We determined whether 34 S. chromogenes, 11 S. epidermidis, and 14 S. simulans isolates originating from bovine milk samples and teat apices (TA) were able to affect biofilm formation and dispersion of S. aureus, and if so, how isolate traits such as the capacity to regulate the S. aureus agr quorum sensing system are determinants in this process. The capacity of an agr-positive S. aureus strain to form biofilm was increased more in the presence of S. chromogenes than in the presence of S. simulans and S. epidermidis isolates and in the presence of NAS isolates that do not harbor biofilm related genes. On the other hand, biofilm dispersion of this particular S. aureus strain was suppressed by NAS as a group, an effect that was more pronounced by isolates from TA. Furthermore, the observed effects on biofilm formation and dispersion of the agr-positive S. aureus strain as well as of an agr-negative S. aureus strain did not depend on the capacity of NAS to repress the agr system.

Comparative analysis of pathogen structure in patients with PJI after primary total hip and knee arthroplasty.

Microbiological profile of pathogens causing periprosthetic joint infection (PJI) after primary total hip (THA) and knee (TKA) arthroplasty varies in different regions, clinics and even departments. The objective of this study was to analyze the pathogen structure in patients with PJI after primary THA and TKA and its influence on the effectiveness of the infection eradication after two-stage reimplantation. We collected the retrospective data of 364 patients-161 with PJI after primary TKA (113 treated in two stages 48 with failure after spacer implantation) and 203 patients with infected THA (127 after successful two-stage reimplantation and 76 with PJI recurrence after the first stage) within the time period from January 2012 to December 2017, treated with two-stage protocol in the single center. A comparative analysis of pathogen structure was performed between cohorts of patients with hip and knee PJI. A subanalysis was made between the subsets comprised from patients with successful two-stage treatment and the subsets with failure to treat the infection. Staphylococcus epidermidis was the most commonly identified pathogen in the full hip and knee cohorts: 30.1% and 32.5%, respectively. However, the percentage of methicillin-resistant Staphylococcus epidermidis (MRSE) among all S. epidermidis isolates was higher in the hip cohort-50% compared with 35% in the knee cohort (p = 0.073). Other coagulase-negative Staphylococci were more common to patients with PJI after primary TKA-10.3% compared with 5% (p < 0.02). Streptococcus sp. caused hip PJI in a larger percentage of cases than in knee PJI (p < 0.01)-7% and 2%, respectively (p < 0.01). Polymicrobial associations were significantly more common in hip PJI compared to knee PJI: 45.3% and 14% of cases, respectively (p < 0.001). The presence of polymicrobial infection significantly raised the risk of PJI recurrence [OR 2 (95% CI from 1.24 to 3.24)] in knee PJI patients and reduced the effectiveness of infection eradication from 73.9% to 47.8%. Comparative analysis showed significant differences in the structure of PJI pathogens in the hip and knee. These findings are useful when choosing treatment strategies and empirical antibiotics regimens, in the management of patients with PJIs after primary hip and knee arthroplasty.

Prevalence and antimicrobial susceptibility pattern of coagulase-negative staphylococci obtained from nares of adult patients admitted to Ahmadu Bello University Teaching Hospital (ABUTH), Zaria

Coagulase-negative staphylococci (CoNS) are part of the normal microbial flora of the skin and mucous membranes. Nasal colonization with antibiotic-resistant CoNS represents both a risk factor for the colonized individual and their immediate contacts. This study determines the antibiotics susceptibility pattern and resistance phenotypes to a specific group of antimicrobial agents in CoNS isolate from the nares of adult patients from Ahmadu Bello University Teaching Hospital (ABUTH), Zaria, Kaduna State, Nigeria. One hundred and twenty-three presumptive staphylococci isolate from nasal colonization surveillance cultures of adult patients were collected from the diagnostic medical microbiology laboratory of ABUTH, Zaria and were characterized using standard microbiological procedures and their susceptibility to commonly used antimicrobial agents determined using the guideline of European committee on antimicrobial susceptibility testing (EUCAST). A total of 60 of the 123 (49%) staphylococcal isolate were CoNS. Characterization of the sixty CoNS isolate showed that the most predominant species were S. chromogenes (30.0%), S xylosus (15.0%) and S. schleiferi subsp. coagulans (13.3%). The highest level of resistance was observed to Cefoxitin (95.0%) and the lowest to Tigecycline (1.7%). S. epidermidis isolates were observed to show ≥60% resistance to all tested antibiotics with the exception of Tigecycline (0%) and Gentamicin (20%). Analysis of the multiple antibiotic resistance index (MARI) showed that majority (96.7%) of the isolates were resistant to 3 or more of the antimicrobial agents. No isolate was resistant to all the tested antimicrobial agents. A very high proportion of the CoNS isolates were resistant to cefoxitin, penicillin, tetracycline, amoxicillin-clavulanate, and vancomycin. In conclusion, the high proportion of isolates with MARI of 0.3 and above indicates a high level of antibiotic use or exposure in the study area. These findings revealed the need for continued surveillance for resistant phenotype to inform clinical therapy decisions

Controlling Growth of Multidrug-Resistant Staphylococci Isolated from Sports Mats: A Report from the Golestan Province, Iran

Background: Gyms are among the places where various human infections can spread. One of the most important strategies to prevent infection spread among athletes is the use of strong and effective disinfectants. Objectives: The aim of this study was to evaluate and compare the antiseptic properties of chlorhexidine gluconate and pomegranate peel extract on staphylococcal isolates from sports mats. Methods: This descriptive-analytical study was performed on 22 Staphylococcus aureus, and Staphylococcus epidermidis isolates from a total of 105 sports mat samples. After identification of multi-drug resistant (MDR) staphylococcal isolates, the antimicrobial effect of chlorhexidine gluconate 20% and pomegranate peel extract was evaluated by broth microdilution according to the instructions of the Clinical and Laboratory Standards Institute. Results: Overall, 14 (66.7%) S. aureus and 8 (28.6%) S. epidermidis isolates resistant to azithromycin, linezolid, ciprofloxacin, vancomycin, and aztreonam were reported as MDR strains. The minimum inhibitory concentration (MIC) of chlorhexidine gluconate, which inhibited the growth of 90% of MDR S. aureus isolates was 250 μg/mL, which was 4-fold lower than the MIC of pomegranate peel extract (MIC90 ≥ 500μg/mL) and 2-fold lower against MDR S. epidermidis isolates (MIC90 ≤ 125 μg/mL). The MIC of chlorhexidine gluconate and pomegranate peel extract against S. aureus isolates differed significantly (P = 0.037). Conclusions: Compared to pomegranate peel extract, chlorhexidine gluconate has a higher antibacterial effect on MDR staphylococcal isolates from sports mats. Further research is required to verify the efficacy of this biocide for disinfection of gyms and sports clubs.

S. epidermidis Isolates from a Tertiary Care Portuguese Hospital Show Very High Antibiotic Non-Susceptible Rates and Significant Ability to Form Biofilms

Healthcare-associated infections (HAIs) have been increasing during recent decades, leading to long hospital stays and high morbidity and mortality rates. The usage of antibiotics therapy against these infections is enhancing the emergence of more multiple-drug resistant strains, in particular in Staphylococcus epidermidis. Hence, this study focused on the resistance pattern of S. epidermidis isolates from clinical settings and its association with phenotypic and molecular traits. Our results showed that HAIs were more prevalent among infants and older adults, and the most frequent type of HAI was central line-associated bloodstream infection. Half of the patients received antibiotic therapy before laboratory diagnosis. Preceding microbiological diagnosis, the number of patients receiving antibiotic therapy increased by 29.1%. Eighty-six per cent of the clinical isolates presented a multidrug resistance (MDR) profile, and a quarter were strong biofilm producers. Furthermore, polysaccharide intercellular adhesin (PIA)-dependent biofilms presented higher biomass production (p = 0.0041) and a higher rate of antibiotic non-susceptibility than PIA-independent biofilms, emphasizing the role of icaABDC operon in infection severity. Therefore, this study suggests that a thorough understanding of the phenotypic and molecular traits of the bacterial cause of the HAIs may lead to a more suitable selection of antibiotic therapy, improving guidance and outcome assessment.

Staphylococcal cassette chromosome mec containing a novel mec gene complex, B4.

ObjectivesTo describe a new subclass of mec class B complex identified in Staphylococcus epidermidis.MethodsFour S. epidermidis isolates obtained from bloodstream infections in patients at University Medical Center Groningen (UMCG) were analysed by phenotypic antibiotic susceptibility testing and WGS.ResultsSequence analysis revealed a new staphylococcal cassette chromosome mec (SCCmec) structure in isolate UMCG335. In this structure, plasmid pUB110 was found to be integrated into SCCmec IVc, creating a new SCCmec subtype, IVUMCG335. SCCmec IVc and a copy of plasmid pUB110 were found in other isolates, UMCG364 and UMCG341, respectively, indicating a probability that SCCmec IVUMCG335 could have evolved at the UMCG. SCCmec of UMCG337 contained a new genetic organization of the mec complex (IS431-ΔmecR1-mecA-IS431-pUB110-IS431-ψIS1272) that we have named B4. This new subclass of mec class B complex originated by IS431-mediated inversion of the DNA segment encompassing the plasmid and most of the genes of the mec complex with the exception of IS1272. As the SCCmec organization in UMCG337 differed by the inversion of an ∼10 kb sequence compared with SCCmec IVUMCG335, we have named it SCCmec subtype IVUMCG337. Isolates UMCG335 and UMCG337 carrying SCCmec IVUMCG335 and IVUMCG337, respectively, were associated with a restriction-modification system and a CRISPR-Cas system, creating a composite island of almost 70 kb.ConclusionsOur findings highlight the importance of IS431 in the evolution of the SCCmec region. The increasing genetic diversity identified in the SCCmec elements imposes a great challenge for SCCmec typing methods and highlights possible difficulties with the SCCmec nomenclature.

Metabolites of bovine-associated non-aureus staphylococci influence expression of Staphylococcus aureus agr-related genes in vitro

Communications via quorum sensing (QS) between non-aureus staphylococci (NAS) and Staphylococcus (S.) aureus in the bovine mammary gland remains largely unexplored. We determined whether 34 S. chromogenes, 11 S. epidermidis, and 14 S. simulans isolates originating from bovine milk samples and teat apices were able to regulate the QS of S. aureus, and if so, how in vitro growth inhibition of S. aureus by NAS, or NAS metabolites, or NAS cells themselves play a role in this process. In co-culture with S. aureus we observed that these 3 NAS species in general downregulated the expression of rnaIII, the effector molecule of the QS system, but this effect was more pronounced in S. chromogenes and S. simulans isolates than in S. epidermidis isolates. In vitro growth inhibition of S. aureus by NAS resulted in a small underestimation of the downregulating effect of NAS on rnaIII expression of S. aureus. Additionally, the culture supernatant of these NAS isolates and supernatant treated with proteinase K expressed greater regulatory activity over S. aureus virulence genes rnaIII, hla, and spa than washed NAS cells suspended in sterile water. These microbial interactions may influence S. aureus virulence and pathogenesis within the host. Isolation and identification of NAS metabolites affecting the QS system of S. aureus might help to develop alternative strategies for treatment and control of S. aureus mastitis.

Staphylococcus aureus and S. epidermidis in biological systems of hospital environment: Antibiotic resistance patterns in regions of Ukraine

Staphylococcus bacteria are ubiquitous and often circulate in the biological systems of the hospital environment. Staphylococci have developed antibiotic resistance mechanisms resulting in a significant medical and economic burden to the healthcare system. The goal of our research was to conduct a comparative analysis of resistance to antibiotics in S. aureus and S. epidermidis isolates found in surgical hospitals in Kharkiv and Poltava regions. In 2013 through 2019, 151,015 and 98,754 tests were made by disc-diffusion method to identify the sensitivity in the S. aureus strains to antibiotics in Kharkiv and Poltava regions respectively. In 2013–2015, 15,589 tests were made in Kharkiv region to identify antibiotics sensitivity in S. epidermidis strains. Comparison of antibiotic resistance of the S. aureus strains in Kharkiv and Poltava regions was performed using the Pearson Chi-square test (χ2) and Fisher’s exact test. The proportion of S. aureus strains resistant to penicillins, cephalosporins, carbapenems, aminoglycosides, and macrolides was higher in Kharkiv region in terms of statistical validity than in Poltava region. Overall, the proportion of S. aureus strains resistant to lincozamids, tetracycline antibiotics, and fluoroquinolones in Poltava region was higher in terms of statistical validity than in Kharkiv region. An analysis of resistance of S. aureus strains to linezolid demonstrated that in Poltava region the proportion of resistant microorganisms was higher in terms of statistical validity in 2013–2014 and in 2016–2018. In Kharkiv region, in 2013 and in 2014, 96.3% and 89.1% of isolated strains of S. aureus respectively, were resistant to vancomycin. In 2019, more than a quarter of the located isolates (26.6%) in Poltava region were resistant to this antibiotic. The analysis of the dynamic of resistance in S. epidermidis isolates demonstrated that in 2015 nearly half of the isolates located in Kharkiv region were insensitive to penicillin antibiotics. Between 2013 and 2015, the spread of resistance to cephalosporins, aminoglycosides, macrolides, and fluoroquinolones among the S. epidermidis isolates noticeably increased. When S. epidermidis resistance to vancomycin was analyzed, a decrease in the proportion of resistant strains from 88.0% in 2013 to 8.7% in 2015 was noted. A promising direction for further research is the creation of passports of microorganism resistance in the regions and various health-care settings, as well as the creation of a unified national database network on microorganism resistance using modern methodologies for determining the phenotypes and genotypes of microorganisms.

Comparative Genomics Analysis Demonstrated a Link Between Staphylococci Isolated From Different Sources: A Possible Public Health Risk.

Coagulase-negative staphylococci (CoNS) have been recovered from different ecological niches, however, little is known about the genetic relatedness of these isolates. In this study, we used whole genome sequencing to compare mecA positive (mecA+) Staphylococcus epidermidis, Staphylococcus haemolyticus and Staphylococcus hominis isolates recovered from hand-touched surfaces from general public settings in East and West London with data of isolates deposited to European Nucleotide Archive (ENA) by other research groups. These included isolates associated with hospital settings (including those recovered from patients), healthy humans, livestock, pets, plants and natural, and other public environments. Using core and accessory phylogenetic analyses we were able to identify that the mecA+ S. epidermidis and S. haemolyticus isolates recovered from general public settings were genetically related to isolates recovered from the bloodstream, urinary tract and eye infections. S. epidermidis isolates recovered in our study were also shown to be genetically related to isolates previously recovered from livestock/livestock housing, whereas S. haemolyticus isolates were genetically related to isolates recovered from a dog and kefir (fermented cow milk drink). MecA+ S. hominis isolates were not genetically related to any isolates recovered from clinical samples but were genetically related to isolates recovered from mosquitoes, air samples (residential areas) and kefir. All three species showed to have genetic relatedness to isolates recovered from healthy humans. These results show that CoNS isolates in this study share genetic similarities with those of different lineages and that mecA+ S. epidermidis and S. haemolyticus isolates found in general public settings in this study may pose a risk to public health.

MLST-Based Analysis and Antimicrobial Resistance of Staphylococcus epidermidis from Cases of Sheep Mastitis in Greece

Simple SummaryData regarding Staphylococcus epidermidis in the multi-locus sequence typing (MLST) database are appraised. Further, work on the association with the resistance of Staphylococcus epidermidis, isolated from cases of sheep mastitis in Greece, to antibiotics is presented. The database includes 1593 isolates from 46 countries, most (76%) of human origin. Of the isolates of animal origin, 72% are from cases of mastitis, among which there were differences between isolates of bovine or ovine origin. Of the isolates from sheep mastitis in Greece, in 58%, resistance to antibiotics was found. There was no association between MLST types and resistance to antibiotics, but antibiotic resistance was more frequent among isolates from flocks being hand- than machine-milked.Staphylococcus epidermidis is an important causal agent of ovine mastitis. A literature search indicated a lack of systematic studies of causal agents of the infection by using multi-locus sequence typing (MLST). The objectives were to analyse MLST-based data and evaluate the antimicrobial resistance of S. epidermidis isolates from ovine mastitis in Greece. The database included 1593 isolates from 46 countries: 1215 of human, 195 of environmental and 134 of animal origin, distributed into 949 sequence types (STs) and cumulatively with 450 alleles therein. Among mastitis isolates, bovine isolates were distributed into 36 different STs and ovine ones into 15 STs. The 33 isolates from ovine mastitis in Greece were in 15 different STs, 6 of these (ST677, ST678, ST700, ST 709, ST710, ST711) assigned for the first time; in addition, 5 alleles (65 for arcC, 59 for aroE, 56 and 57 for gtr and 48 for tpiA) were identified for the first time. The spanning tree of these isolates included 15 nodes and 14 edges (i.e., branches). Among these isolates, 19 showed resistance to antimicrobial agents (tetracycline, penicillin, fucidic adic, erythromycin, clindamycin, cefoxitin). Resistance-related genes (tetK, tetT, msrA, tetM, tetS, ermC, mecA) were detected. There was no association between STs and resistance to antimicrobial agents. Isolates with antimicrobial resistance were recovered more often from flocks where hand-milking was practised.

Distinct clonal lineages and within-host diversification shape invasive Staphylococcus epidermidis populations.

S. epidermidis is a substantial component of the human skin microbiota, but also one of the major causes of nosocomial infection in the context of implanted medical devices. We here aimed to advance the understanding of S. epidermidis genotypes and phenotypes conducive to infection establishment. Furthermore, we investigate the adaptation of individual clonal lines to the infection lifestyle based on the detailed analysis of individual S. epidermidis populations of 23 patients suffering from prosthetic joint infection. Analysis of invasive and colonizing S. epidermidis provided evidence that invasive S. epidermidis are characterized by infection-supporting phenotypes (e.g. increased biofilm formation, growth in nutrient poor media and antibiotic resistance), as well as specific genetic traits. The discriminating gene loci were almost exclusively assigned to the mobilome. Here, in addition to IS256 and SCCmec, chromosomally integrated phages was identified for the first time. These phenotypic and genotypic features were more likely present in isolates belonging to sequence type (ST) 2. By comparing seven patient-matched nasal and invasive S. epidermidis isolates belonging to identical genetic lineages, infection-associated phenotypic and genotypic changes were documented. Besides increased biofilm production, the invasive isolates were characterized by better growth in nutrient-poor media and reduced hemolysis. By examining several colonies grown in parallel from each infection, evidence for genetic within-host population heterogeneity was obtained. Importantly, subpopulations carrying IS insertions in agrC, mutations in the acetate kinase (AckA) and deletions in the SCCmec element emerged in several infections. In summary, these results shed light on the multifactorial processes of infection adaptation and demonstrate how S. epidermidis is able to flexibly repurpose and edit factors important for colonization to facilitate survival in hostile infection environments.

The Correlation between icaA and icaD Genes with Biofilm Formation Staphylococcus epidermidis In Vitro

This study was conducted to identify the presence of icaA and icaD genes in S. epidermidis and to analyze the relationship between the presence of icaA and icaD genes with the ability of in vitro biofilm formation in S. epidermidis. S. epidermidis isolates from patients and healthy people were collected and PCR was examined to detect icaA and icaD genes. which then continued to examine the ability of biofilm formation by the method of Congo Red Agar. The results of this genotypic and phenotypic examination were then tested for correlation with statistical tests using SPSS 23.0. A total of 40 S. epidermidis isolates were collected, consisting of 20 clinical isolates and 20 isolates of normal flora. The icaA gene was positive in 5 isolates (12.5%), and 8 isolates (20%) were positive for the icaD gene, 3 isolates with icaA and icaD were both positive. One hundred percent of isolates with icaA or icaD positively formed biofilms, but there were 15 isolates (42.9%) who did not have the icaA gene but showed the ability to form biofilms, while 12 isolates (37.5%) who did not have the icaD gene also formed biofilms. Fifty percent of S. epidermidis isolates showed the ability to form biofilms at CRA. The Fisher Exact test showed a significant relationship between the icaA gene and the ability of biofilm formation (p=0.047 (p&lt;0.05)) as well as the icaD gene (p=0.03 (p&lt;0.05)). The icaA and icaD genes have a significant relationship to biofilm formation in S. epidermidis. There was another mechanism in the formation of biofilms that are not dependent on the ica gene.