Pathogenic features of clinically significant coagulase-negative staphylococci in hospital and community infections in Benin

Detection of mecA positive staphylococcal species in a wastewater treatment plant in South Africa

We investigated the prevalence of antibiotic resistant staphylococci and detection of resistant, virulence, and Spa genes in a South African wastewater treatment plant. Species identified were Staphylococcus aureus, S. lentus, S. arlettae, S. cohnii, S. haemolyticus, S. nepalensis, S. sciuri (now Mammaliicoccus sciuri), and S. xylosus. Isolates showed high resistance to methicillin (91%), ampicillin (89%), ciprofloxacin (86%), amoxycillin (80%), ceftazidime (74%), and cloxacillin (71%). Multiple antibiotic resistance (MAR) index for the isolates exceeded 0.2 (0.50-0.70). Among the isolates, 77% were mecA-positive. All S. aureus strains were positive for nuc and 7 Spa gene types. The present study highlights possibility of treated wastewaters being potential reservoir for antibiotic-resistant staphylococci. This is a cause for concern as wastewater effluents are decanted into environmental waters and these are, in many cases, used for various purposes including recreation (full contact), religious (full body submersion), and drinking water for some rural communities and water for livestock.

Evaluation of Enterotoxins and Antimicrobial Resistance in Microorganisms Isolated from Raw Sheep Milk and Cheese: Ensuring the Microbiological Safety of These Products in Southern Brazil

This study emphasizes the importance of monitoring the microbiological quality of animal products, such as raw sheep's milk and cheese, to ensure food safety. In Brazil, there is currently no legislation governing the quality of sheep's milk and its derivatives. Therefore, this study aimed to evaluate: (i) the hygienic-sanitary quality of raw sheep's milk and cheese produced in southern Brazil; (ii) the presence of enterotoxins and Staphylococcus spp. in these products; and (iii) the susceptibility of the isolated Staphylococcus spp. to antimicrobial drugs and the presence of resistance genes. A total of 35 samples of sheep's milk and cheese were examined. The microbiological quality and presence of enterotoxins were accessed using Petrifilm and VIDAS SET2 methods, respectively. Antimicrobial susceptibility tests were conducted using VITEK 2 equipment and the disc diffusion method. The presence of resistance genes tet(L), sul1, sul2, ermB, tetM, AAC(6)', tetW, and strA were evaluated through PCR. In total, 39 Staphylococcus spp. were obtained. The resistance genes tetM, ermB, strA, tetL, sul1, AAC(6)', and sul2 were detected in 82%, 59%, 36%, 28%, 23%, 3%, and 3% of isolates, respectively. The findings revealed that both raw sheep's milk and cheese contained Staphylococcus spp. that exhibited resistance to antimicrobial drugs and harbored resistance genes. These results underscore the immediate need for specific legislation in Brazil to regulate the production and sale of these products.

Establishment of a Fast Diagnostic Method for Sepsis Pathogens Based on M1 Bead Enrichment

Blood culture-based sepsis diagnostic methods usually cannot obtain positive results in a timely manner. Molecular diagnostic methods, such as real-time PCR without blood culture, would be more time-saving and suitable for pathogenic diagnosis of sepsis, while their sensitivities have always been unsatisfactory for the usually low concentration of pathogens in the blood of sepsis patients. In this study, we established a fast diagnostic method using magnetic beads coated with human recombined mannose-binding lectin that makes it possible to concentrate pathogens from human plasma that have low concentrations of pathogens. With subsequent microculture (MC) and real-time PCR, this method allowed the detection of 1-10 CFUs/ml of Staphylococcus aureus, Group A Streptococcus, Escherichia coli, Pseudomonas aeruginosa, Candida tropicalis, or C. albicans from human plasma within 9.5 h, which was 21-80 h earlier than blood culture. The combination of pathogen enrichment and MC made the detection of sepsis-causing pathogens more time-saving and more sensitive than blood culture or real-time PCR alone.

Stability and Resistance to Proteolysis of Enterotoxins SEC and SEL Produced by Staphylococcus epidermidis and Staphylococcus aureus

The only staphylococcal enterotoxins produced by Staphylococcus epidermidis include SEC_epi and SEL_epi, whereas Staphylococcus aureus produces orthologous SECs and SEL having different sequences. We compared S. epidermidis and S. aureus SECs and SELs in terms of resistance to proteolysis and both, thermal and chemical stability. We show that SEC_epi and SEL_epi produced by S. epidermidis have similar resistance to proteolysis if compared with their respective orthologues produced by S. aureus. Studied S. epidermidis and S. aureus SEC variants incubated with pepsin at pH 2.0 were found to be more resistant to proteolysis than SELs. SELs turned out to be more resistant than SECs to proteolysis with trypsin at pH 8.0. SEC_epi was found to be more resistant to thermal denaturation if compared with its S. aureus orthologues. The S. epidermidis and S. aureus SEC variants were found to have higher thermal stability than SELs. Our data indicate that, due to their high stability, the enterotoxins SEC_epi and SEL_epi produced in food by S. epidermidis may pose a food safety risk comparable with that posed by S. aureus enterotoxins.

Isolation and Identification of Staphylococcus Species Obtained from Healthy Companion Animals and Humans

The close contact between people and their pets has generated the exchange of skin microbiota, accompanied by bacteria that present resistance to antibiotics. Staphylococcus spp., opportunistic pathogens present in the skin and mucosa of mammals, have had their importance recognized in human and veterinary medicine. The objectives of this study were to identify Staphylococcus spp. present in isolates from the nostrils of healthy humans, dogs and cats as well as to determine their phenotype of resistance to methicillin. Strain identification was performed by MALDI-TOF mass spectrometry and antimicrobial susceptibility was determined using a disk diffusion assay for 12 antibiotics. Sixty humans (veterinary and technicians), sixty dogs and sixty cats were sampled; of them, 61.6%, 56.6% and 46.6%, respectively, carried Staphylococcus spp. in their nostrils, and only two people carried two different species of Staphylococcus in the only anatomical site sampled. A methicillin-resistant phenotype was present in 48.7% of the humans, 26.5% of the dogs and 57.1% of the cats, and sampled. These results demonstrate the presence of Staphylococcus spp. strains resistant to methicillin in personnel who work in contact with animals, as well as in dogs and cats that entered the same hospital or veterinary clinic, which alerts us to the potential transfer of these strains to or between people, dogs and/or cats.

The Insights of Microbes' Roles in Wound Healing: A Comprehensive Review

A diverse range of normal flora populates the human skin and numbers are relatively different between individuals and parts of the skin. Humans and normal flora have formed a symbiotic relationship over a period of time. With numerous disease processes, the interaction between the host and normal flora can be interrupted. Unlike normal wound healing, which is complex and crucial to sustaining the skin’s physical barrier, chronic wounds, especially in diabetes, are wounds that fail to heal in a timely manner. The conditions become favorable for microbes to colonize and establish infections within the skin. These include secretions of various kinds of molecules, substances or even trigger the immune system to attack other cells required for wound healing. Additionally, the healing process can be slowed down by prolonging the inflammatory phase and delaying the wound repair process, which causes further destruction to the tissue. Antibiotics and wound dressings become the targeted therapy to treat chronic wounds. Though healing rates are improved, prolonged usage of these treatments could become ineffective or microbes may become resistant to the treatments. Considering all these factors, more studies are needed to comprehensively elucidate the role of human skin normal flora at the cellular and molecular level in a chronic injury. This article will review wound healing physiology and discuss the role of normal flora in the skin and chronic wounds.

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.

Epidemiology and Pathogenesis of Staphylococcus Bloodstream Infections in Humans: a Review

Staphylococci are among the most frequent human microbiota components associated with the high level of bloodstream infection (BSI) episodes. In predisposed patients, there is a high risk of transformation of BSI episodes to sepsis. Both bacterial and host factors are crucial for the outcomes of BSI and sepsis. The highest rates of BSI episodes were reported in Africa, where these infections were up to twice as high as the European rates. However, there remains a great need to analyze African data for comprehensive quantification of staphylococcal BSI prevalence. The lowest rates of BSI exist in Australia. Asian, European, and North American data showed similar frequency values. Worldwide analysis indicated that both Staphylococcus aureus and coagulase-negative staphylococci (CoNS) are the most frequent BSI agents. In the second group, the most prevalent species was Staphylococcus epidermidis, although CoNS were not identified at the species level in many studies. The lack of a significant worldwide decrease in BSI episodes indicates a great need to implement standardized diagnostic methods and research etiological factors using advanced genetic methods.

Insights into the epidemiology of methicillin-resistant coagulase-negative Staphylococci carriage in community-based drug users

BACKGROUND

Coagulase-negative Staphylococci (CoNS) are opportunistic pathogens. Methicillin-resistant CoNS (MRCoNS) remain a major cause of nosocomial infections, but limited information is available in communities. We, therefore, aimed to investigate the epidemiology of CoNS nasal carriage, especially MRCoNS in community-based drug users.

METHODS

Drug users were included in the cross-sectional study from three communities in Guangzhou, China. A face-to-face questionnaire was used to collect individual information and nasal swabs were collected to identify CoNS and MRCoNS isolates. Phenotypic and genotypic characterization of MRCoNS isolates were detected by using the disk diffusion method and polymerase chain reaction assays. Factors impacting MRCoNS carriage were assessed and estimated odds ratios (ORs) and 95% confidence intervals (CIs) by using logistic regression models.

RESULTS

Overall, 353 drug users were eligible and included in the study. The prevalence of CoNS and MRCoNS were 42.78% and 29.18%, respectively. Having a history of being in prison (aOR = 2.16, 95% CI: 1.10-4.22) and a history of heroin snorting in the past 6 months (aOR = 1.87, 95% CI: 1.14-3.05) were risk factors for MRCoNS nasal carriage in drug users. The proportions of multidrug resistance for CoNS and MRCoNS isolates were respectively 54.38% and 66.07%. The predominant multidrug resistance pattern for CoNS and MRCoNS isolates was simultaneously non-susceptible to penicillin, cefoxitin and trimethoprim-sulfamethoxazole. MRCoNS isolates that were positive for erythromycin- (χ² = 15.49, P < 0.001), tetracycline- (χ² = 44.88, P < 0.001), penicillin- (χ² = 3.86, P = 0.049), clindamycin- (χ² = 4.18, P = 0.028), and gentamicin- (χ² = 20.66, P < 0.001) resistance genes had significantly higher rates of resistance to corresponding antibiotics.

CONCLUSIONS

The prevalence of MRCoNS nasal carriage was high in community-based drug users. Drug users with risk factors should be paid greater attention to. The use of antibiotics in drug users needs further investigation and control.

Enterotoxigenic Potential of Coagulase-Negative Staphylococci from Ready-to-Eat Food

Although coagulase-positive staphylococci are considered to be the main factor responsible for food poisoning, an increasing role for the coagulase-negative staphylococci in the production of enterotoxins has been observed in recent years. This study was conducted to assess the occurrence of genes responsible for the production of staphylococcal enterotoxins (SE), enterotoxin-like toxins (SEI) and toxic shock syndrome toxin-1 (TSST-1) in coagulase-negative staphylococci (CoNS) isolated from ready-to-eat food from bars and restaurants. One hundred and eighteen CoNS strains were tested using polymerase chain reaction (PCR) to five superantigenic toxin genes, including five different types of classical enterotoxins (sea, seb, sec, sed and see) and the toxic shock syndrome toxin-1 (tsst-1) as well as to supertoxin-like genes. PCR-positive isolates were then tested using immunoenzymatic methods (SET-RPLA, Vidas SET 2) for toxin expression. Out of 118 CoNS strains, the presence of staphylococcal enterotoxins was confirmed in 72% of them. The most frequently found enterotoxin-like genotype was ser, selu. Two of the tested strains had up to ten different enterotoxin genes in the genome at the same time. Although no production of enterotoxins was detected in the CoNS, which means that their possible role in the epidemiology of food-borne diseases is minimal, the data demonstrated that the toxigenic capacity of the CoNS should not be ignored, and that this group of microorganisms should be continuously monitored in food.

Review of Clinically and Epidemiologically Relevant Coagulase-Negative Staphylococci in Africa

Coagulase-negative staphylococci (CoNS) have engendered substantial interest in recent years as pathogenic causes of infections in both human and veterinary medicine, especially in the immunocompromised, critically ill, long-term hospitalized and in those harboring invasive medical devices such as catheters. They have been implicated in infections such as urinary tract infections, bloodstream infections, and invasive device-related infections, and are responsible for substantial economic losses in livestock production. The advancement of diagnostic techniques has increased our understanding of their molecular mechanisms of pathogenicity, even though distinguishing between innocuousness and pathogenicity is still challenging. The incidence of CoNS varied across the continent in humans and animals (mainly cattle), ranging from 6% to 68% in suspected human infections and from 3% to 61.7% in suspected animal infections, distributed across different geographic locations. Furthermore, there were varying antibiotic resistance patterns observed in CoNS isolates, with high methicillin resistance in some cases, leading to crossresistance against many antibiotics. Staphylococcus epidermidis, Staphylococcus haemolyticus, and Staphylococcus xylosus were most commonly reported in studies herein reviewed, while the enterotoxin C gene, atl E gene, ica gene, and hemolysin virulence factors were linked with enhanced pathogenicity. Advancement in identification and typing methods, including whole genome sequencing, virulence screening, and the assessment of the immune status of subjects in studies will help to thoroughly assess the true pathogenic potential of isolated CoNS species in developing countries. Careful antibiotic stewardship guidelines should be followed due to the ability of CoNS to develop multidrug resistance.

Identification of hemolysin encoding genes and their association with antimicrobial resistance pattern among clinical isolates of coagulase-negative Staphylococci

OBJECTIVE

Coagulase-negative staphylococci (CoNS) are as considered opportunistic pathogens which capable of producing several toxins, enzymes and resistance genes. The current study aimed to determine the occurrence of different hemolysins genes and patterns of antibiotic resistance among CoNS species.

RESULTS

The highest frequency of antibiotic resistance was observed against cefoxitin in 49 isolates (53.8%), and the lowest resistance was against novobiocin in 5 isolates (5.5%). None of the isolates was resistant to vancomycin. The prevalence of hla, hla_yidD, hld, and hlb genes was: 87.9%, 62.6%, 56%, and 47.3%, respectively. The hla/yidD and hld genes were detected in 69.4% of S. epidermidis and the hla gene in 94.6% of S. haemolyticus isolates; the hlb gene was detected in 53.1% of the S. epidermidis isolates. The mecA gene was identified in 50 (55%) of the CoNS isolates. In conclusion, the results of statistical analysis showed that the hld gene had a significant association with resistance to levofloxacin and erythromycin antibiotics, the hlb with clindamycin resistance and the hla/yidD with rifampicin and novobiocin resistance. The results of this study showed that there is a significant relationship between hemolysin encoding genes and antibiotic resistance patterns; therefore, detection of virulence factors associated with antibiotic resistance has become a significant issue of concern.

Multi-drug resistance traits of methicillin-resistant Staphylococcus aureus and other Staphylococcal species from clinical and environmental sources

Multi-drug resistance traits of Staphylococcus species especially methicillin-resistant Staphylococcus aureus (MRSA) in the clinical settings are well established. Of environmental concern is hospital effluents discharging into wastewaters. This article investigated the prevalence and detection of antibiotic resistance genes in Staphylococcus species from clinical and environmental sources in Ile-Ife, Nigeria. Standard culture-based and molecular protocols were used. Seventy-six (27 clinical, 14 hospital effluent and 35 environmental) Staphylococcus isolates were recovered: 56.58% were coagulase-negative and 43.42% coagulase-positive (S. aureus). For the clinical isolates, 10, 6, 4, 4 and 1 were isolated from urine, skin, wounds, blood and pus, respectively. Isolates were resistant to methicillin and amoxycillin (91.7%), cloxacillin (88.0%), ciprofloxacin (84.0%), ofloxacin (83.3%), azithromycin (78.0%), ceftazidime (76.0%), gentamycin (75.0%), cefuroxime (75.0%) and erythromycin (72.0%). Nearly, all isolates (90.8%) had multiple antibiotic resistance (MAR) index >0.2. Overall MAR indices for Staphylococcus species isolated from the clinical, hospital effluent and environmental wastewaters were relatively similar (0.482; 0.500; 0.435). mecA, nuc and luk-pvl genes were detected in S. aureus, while mecA was detected in S. arlettae, S. sciuri, S. cohnii, S. epidermidis and S. saprophyticus. This study informs on the potential contamination of environmental waters downstream from hospitals and possible impacts that this could have on human and animal health.

Evolution of Antibiotic Resistance of Coagulase-Negative Staphylococci Isolated from Healthy Turkeys in Egypt: First Report of Linezolid Resistance

Coagulase-negative staphylococci (CoNS) are gaining much attention as causative agents of serious nosocomial infections in humans. This study aimed to determine the prevalence and phenotypic antimicrobial resistance of CoNS as well as the presence of resistance-associated genes in CoNS isolated from turkey farms in Egypt. Two hundred and fifty cloacal swabs were collected from apparently healthy turkeys in Egypt. Suspected isolates were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The susceptibility testing of CoNS isolates against 20 antimicrobial agents was performed using the broth microdilution test. The presence of resistance-associated genes like mecA, vanA, blaZ, erm(A), erm(B), erm(C), aac-aphD, optrA, valS, and cfr was determined. Thirty-nine CoNS were identified. All isolates were phenotypically resistant to trimethoprim/sulfamethoxazole, penicillin, ampicillin, and tetracycline. The resistance rates to erythromycin, chloramphenicol, oxacillin, daptomycin, and tigecycline were 97.4%, 94.9%, 92.3%, 89.7%, and 87.2%, respectively. Thirty-one isolates were resistant to linezolid (79.5%). Low resistance rate was detected for both imipenem and vancomycin (12.8%). The erm(C) gene was identified in all erythromycin phenotypically resistant isolates, whereas two resistant isolates possessed three resistance-conferring genes erm(A), erm(B), and erm(C). The cfr and optrA genes were detected in 11 (35.5%) and 12 (38.7%) of the 31 linezolid-resistant isolates. The mecA, aac-aphD, and blaZ genes were identified in 22.2%, 41.9%, and 2.6% of phenotypically resistant isolates to oxacillin, gentamicin, and penicillin, respectively. This is the first study revealing the correlation between linezolid resistance and presence of cfr and optrA genes in CoNS isolates from Egypt, and it can help to improve knowledge about the linezolid resistance mechanism.

Comparative Genomic Analysis of Staphylococcus haemolyticus Reveals Key to Hospital Adaptation and Pathogenicity

Staphylococcus haemolyticus is a skin commensal gaining increased attention as an emerging pathogen of nosocomial infections. However, knowledge about the transition from a commensal to an invasive lifestyle remains sparse and there is a paucity of studies comparing pathogenicity traits between commensal and clinical isolates. In this study, we used a pan-genomic approach to identify factors important for infection and hospital adaptation by exploring the genomic variability of 123 clinical isolates and 46 commensal S. haemolyticus isolates. Phylogenetic reconstruction grouped the 169 isolates into six clades with a distinct distribution of clinical and commensal isolates in the different clades. Phenotypically, multi-drug antibiotic resistance was detected in 108/123 (88%) of the clinical isolates and 5/46 (11%) of the commensal isolates (p < 0.05). In the clinical isolates, we commonly identified a homolog of the serine-rich repeat glycoproteins sraP. Additionally, three novel capsular polysaccharide operons were detected, with a potential role in S. haemolyticus virulence. Clinical S. haemolyticus isolates showed specific signatures associated with successful hospital adaption. Biofilm forming S. haemolyticus isolates that are resistant to oxacillin (mecA) and aminoglycosides (aacA-aphD) are most likely invasive isolates whereas absence of these traits strongly indicates a commensal isolate. We conclude that our data show a clear segregation of isolates of commensal origin, and specific genetic signatures distinguishing the clinical isolates from the commensal isolates. The widespread use of antimicrobial agents has probably promoted the development of successful hospital adapted clones of S. haemolyticus clones through acquisition of mobile genetic elements or beneficial point mutations and rearrangements in surface associated genes.

Coagulase-Negative Staphylococci Pathogenomics

Coagulase-negative Staphylococci (CoNS) are skin commensal bacteria. Besides their role in maintaining homeostasis, CoNS have emerged as major pathogens in nosocomial settings. Several studies have investigated the molecular basis for this emergence and identified multiple putative virulence factors with regards to Staphylococcus aureus pathogenicity. In the last decade, numerous CoNS whole-genome sequences have been released, leading to the identification of numerous putative virulence factors. Koch’s postulates and the molecular rendition of these postulates, established by Stanley Falkow in 1988, do not explain the microbial pathogenicity of CoNS. However, whole-genome sequence data has shed new light on CoNS pathogenicity. In this review, we analyzed the contribution of genomics in defining CoNS virulence, focusing on the most frequent and pathogenic CoNS species: S. epidermidis, S. haemolyticus, S. saprophyticus, S. capitis, and S. lugdunensis.

Decreased susceptibility to chlorhexidine and distribution of qacA/B genes among coagulase-negative Staphylococcus clinical samples

Background

Healthcare-associated infection (HAI) is a major public health problem. As a form of prevention and control, preparations of chlorhexidine are used extensively; however, the reduction of susceptibility to chlorhexidine has been reported. The aim of this study was to investigate the susceptibility to chlorhexidine and the distribution of the qacA/B genes in 211 clinical isolates of coagulase-negative Staphylococci (CoNS).

Methods

CoNS were identified by conventional biochemical tests. Antimicrobial susceptibility was tested by disk-diffusion. Minimum inhibitory concentration (MIC) of chlorhexidine was determined by agar dilution test; detection of the qacA/B and mecA genes were evaluated by PCR.

Results

The most frequently isolated species were S. epidermidis, S. hominis hominis, S. auricularis, and S. haemolyticus, respectively. The strains presented a multidrug resistance profile of 87%, including methicillin resistance. Reduced susceptibility to chlorhexidine was observed in 31%. The qacA/B genes were detected in samples resistant (32/32) and susceptible (17/32) to chlorhexidine. The vast majority (94%) of the samples with reduced susceptibility to chlorhexidine were multidrug resistant.

Conclusions

Our results show that qacA/B genes are not restricted to strains expressing chlorhexidine resistance. Further studies are needed to understand how the expression of these genes occurs.

Comparative genomic analysis of Staphylococcus lugdunensis shows a closed pan-genome and multiple barriers to horizontal gene transfer

Background

Coagulase negative staphylococci (CoNS) are commensal bacteria on human skin. Staphylococcus lugdunensis is a unique CoNS which produces various virulence factors and may, like S. aureus, cause severe infections, particularly in hospital settings. Unlike other staphylococci, it remains highly susceptible to antimicrobials, and genome-based phylogenetic studies have evidenced a highly conserved genome that distinguishes it from all other staphylococci.

Results

We demonstrate that S. lugdunensis possesses a closed pan-genome with a very limited number of new genes, in contrast to other staphylococci that have an open pan-genome. Whole-genome nucleotide and amino acid identity levels are also higher than in other staphylococci. We identified numerous genetic barriers to horizontal gene transfer that might explain this result. The S. lugdunensis genome has multiple operons encoding for restriction-modification, CRISPR/Cas and toxin/antitoxin systems. We also identified a new PIN-like domain-associated protein that might belong to a larger operon, comprising a metalloprotease, that could function as a new toxin/antitoxin or detoxification system.

Conclusion

We show that S. lugdunensis has a unique genome profile within staphylococci, with a closed pan-genome and several systems to prevent horizontal gene transfer. Its virulence in clinical settings does not rely on its ability to acquire and exchange antibiotic resistance genes or other virulence factors as shown for other staphylococci.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-4978-1) contains supplementary material, which is available to authorized users.

Coagulase-Negative Staphylococci Isolated from Human Bloodstream Infections Showed Multidrug Resistance Profile

Coagulase-negative staphylococci (CNS) are important pathogens causing nosocomial infections worldwide with increasing resistance to antimicrobials. The aim of this study was to characterize resistance aspects of CNS isolated from patients with bloodstream infections acquired in hospitals in Belo Horizonte, MG, Brazil. Staphylococcus strains were characterized using repetitive sequence-based polymerase chain reaction (rep-PCR) fingerprinting with (GTG)₅ primer. Phenotypic resistance was analyzed using AST-P5085 card (bioMérieuxVitek^®). PCR was used to detect mecA, vanA, blaZ, ermA/B/C, aac-aphD, and SCC-mec. For statistical analyses, we used hierarchical cluster, chi-square test (χ²), and correspondence. Several clusters were formed within the same species using (GTG)₅ primer, and strains showed resistance to the following antimicrobials: benzylpenicillin (100%); oxacillin (93.1%); gentamicin (36.3%); ciprofloxacin (63.7%); moxifloxacin (32.7%); norfloxacin (81.0%); erythromycin (86.2%); clindamycin (75.8%); linezolid, teicoplanin and vancomycin (1.7%); tigecycline (0%); fusidic acid (10.35%); rifampicin (13.7%); and trimethoprim/sulfamethoxazole (46.5%). Regarding genotypic analyses, 40%, 0%, 78%, 42%, 100%, 24%, and 30% were positive for mecA, vanA, blaZ, ermA, ermB, ermC, and aac-aphD, respectively. Regarding staphylococcal cassette mec (SCCmec) type, 3.4% presented type I; 5.0% type II; 27.1% type III; 20.3% type IIIA; and 32.2% type IIIB. Six clusters were formed and frequency distributions of resistant strains to oxacillin, gentamicin, ciprofloxacin, moxifloxacin, norfloxacin, erythromycin, clindamycin, linezolid, teicoplanin, vancomycin, fusidic acid, rifampicin, and trimethoprim/sulfamethoxazole, and mecA, blaZ, ermC, aac-aphD, and SCCmec type differed (p < 0.001). In conclusion, the strains investigated in this study were multidrug resistant and carried multiple antibiotic resistance genes.

Characterization of Human Type C Enterotoxin Produced by Clinical S. epidermidis Isolates

Staphylococcal Enterotoxins (SEs) are superantigens (SAg) originally produced by S. aureus, but their presence in coagulase negative staphylococci (CNS) has long been suspected. This study aims to better characterize a novel C-like enterotoxin expressed by clinical S. epidermidis strains, called SEC_epi. We isolated and characterized SEC_epi for its molecular and functional properties. The toxin was structurally modeled according to its significant similarity with S. aureus SEC3. Most of SEC amino acid residues important for the formation of the trimolecular Major Histocompatibility Complex II MHCII-SEC-T Cell Receptor TCR complex are conserved in SEC_epi. The functional properties of SEC_epi were estimated after cloning, expression in E. coli, and purification. The recombinant SEC_epi toxin exhibits biological characteristics of a SAg including stimulation of human T-cell mitogenicity, inducing and releasing high cytokines levels: IL-2, -4, -6, -8, -10, IFN-γ, TNF-α and GM-CSF at a dose as low as 3.7 pM. Compared to SEC_aureus, the production of pro-sepsis cytokine IL-6 is significantly higher with SEC_epi-activated lymphocytes. Furthermore, SEC_epi is stable to heat, pepsin or trypsin hydrolysis. The SEC_epi superantigen produced by CNS is functionally very close to that of S. aureus, possibly inducing a systemic inflammatory response at least comparable to that of SEC_aureus, and may account for S. epidermidis pathogenicity.

Comparative Genomics and Identification of an Enterotoxin-Bearing Pathogenicity Island, SEPI-1/SECI-1, in Staphylococcus epidermidis Pathogenic Strains

Staphylococcus epidermidis is a leading cause of nosocomial infections, majorly resistant to beta-lactam antibiotics, and may transfer several mobile genetic elements among the members of its own species, as well as to Staphylococcus aureus; however, a genetic exchange from S. aureus to S. epidermidis remains controversial. We recently identified two pathogenic clinical strains of S. epidermidis that produce a staphylococcal enterotoxin C3-like (SEC) similar to that by S. aureus pathogenicity islands. This study aimed to determine the genetic environment of the SEC-coding sequence and to identify the mobile genetic elements. Whole-genome sequencing and annotation of the S. epidermidis strains were performed using Illumina technology and a bioinformatics pipeline for assembly, which provided evidence that the SEC-coding sequences were located in a composite pathogenicity island that was previously described in the S. epidermidis strain FRI909, called SePI-1/SeCI-1, with 83.8–89.7% nucleotide similarity. Various other plasmids were identified, particularly p_3_95 and p_4_95, which carry antibiotic resistance genes (hsrA and dfrG, respectively), and share homologies with SAP085A and pUSA04-2-SUR11, two plasmids described in S. aureus. Eventually, one complete prophage was identified, ΦSE90, sharing 30 out of 52 coding sequences with the Acinetobacter phage vB_AbaM_IME200. Thus, the SePI-1/SeCI-1 pathogenicity island was identified in two pathogenic strains of S. epidermidis that produced a SEC enterotoxin causing septic shock. These findings suggest the existence of in vivo genetic exchange from S. aureus to S. epidermidis.

Reduction of bacterial burden by copper alloys on high-touch athletic center surfaces

BACKGROUND

Athletic centers have been locations for the transmission of community-acquired infections. This study assessed the capacity of copper alloys to reduce the bacterial burden associated with high-touch athletic center equipment. Copper alloy weights and grips were rotated with rubber coated and stainless steel controls in an undergraduate college athletic center over a 16-month period. The athletic center is used by college athletic teams, student body, and local community.

METHODS

The primary outcome was to compare bacterial burdens on copper and control grips by swabbing surfaces. Significance was determined using the nonparametric Mann-Whitney U test with significance assessed at P < .05. Secondary outcomes included characterizing bacterial communities on surfaces and conducting antibiotic susceptibility testing using the Kirby-Bauer disk diffusion method.

RESULTS

Control athletic center components carried bacterial loads 94% larger than those found on copper alloy components. Bacterial community characterization revealed Staphylococcus to be the most common bacterial genus found on grip surfaces. Antibiotic resistance testing of the Staphylococcus isolates revealed that all isolates were susceptible to vancomycin and linezolid, whereas 35% of copper alloy isolates and 44% of control isolates were resistant to erythromycin.

CONCLUSIONS

Copper alloys can mitigate the bacterial burden on high-touch surfaces. Strategically placing copper alloys in areas of high human contact can augment infection control efforts and potentially decrease community-acquired infections in athletic centers.

Linezolid-Associated Hypoglycemia

Our case describes a 77-year-old, African American male who was experiencing recurrent hypoglycemic episodes, which resulted in two emergency department (ED) visits and a subsequent inpatient admission during his second ED visit. He was prescribed linezolid 600 mg twice daily for 14 days for the treatment of a Staphylococcus hominis urinary tract infection. Nine and a half days into therapy, the patient began having recurrent hypoglycemic episodes. These episodes persisted despite repeated intravenous dextrose boluses. The patient’s linezolid was discontinued during the second day of his inpatient admission. After a brief lag period after the final linezolid administration, the patient’s blood glucose level stabilized within normal limits. He was later discharged home. The Naranjo scale scores the causality of this reaction between 4 and 8, indicating possible to probable causality. The patient had a follow-up appointment with his primary care physician 2 weeks after discharge, with no noted blood glucose complications. Two months after discharge, he entered hospice care for his advancing heart failure and later expired due to causes unrelated to blood glucose complications.

Rapid identification of staphylococci by Raman spectroscopy

Clinical treatment of the infections caused by various staphylococcal species differ depending on the actual cause of infection. Therefore, it is necessary to develop a fast and reliable method for identification of staphylococci. Raman spectroscopy is an optical method used in multiple scientific fields. Recent studies showed that the method has a potential for use in microbiological research, too. Our work here shows a possibility to identify staphylococci by Raman spectroscopy. We present a method that enables almost 100% successful identification of 16 of the clinically most important staphylococcal species directly from bacterial colonies grown on a Mueller-Hinton agar plate. We obtained characteristic Raman spectra of 277 staphylococcal strains belonging to 16 species from a 24-hour culture of each strain grown on the Mueller-Hinton agar plate using the Raman instrument. The results show that it is possible to distinguish among the tested species using Raman spectroscopy and therefore it has a great potential for use in routine clinical diagnostics.

Whole-Genome Sequencing of Seven Strains of Staphylococcus lugdunensis Allows Identification of Mobile Genetic Elements

Coagulase negative staphylococci are normal inhabitant of the human skin flora that account for an increasing number of infections, particularly hospital-acquired infections. Staphylococcus lugdunensis has emerged as a most virulent species causing various infections with clinical characteristics close to what clinicians usually observe with Staphylococcus aureus and both bacteria share more than 70% of their genome. Virulence of S. aureus relies on a large repertoire of virulence factors, many of which are encoded on mobile genetic elements. S. lugdunensis also bears various putative virulence genes but only one complete genome with extensive analysis has been published with one prophage sequence (φSL2) and a unique plasmid was previously described. In this study, we performed de novo sequencing, whole genome assembly and annotation of seven strains of S. lugdunensis from VISLISI clinical trial. We searched for the presence of virulence genes and mobile genetics elements using bioinformatics tools. We identified four new prophages, named φSL2 to φSL4, belonging to the Siphoviridae class and five plasmids, named pVISLISI_1 to pVISLISI_5. Three plasmids are homologous to known plasmids that include, amongst others, one S. aureus plasmid. The two other plasmids were not described previously. This study provides a new context for the study of S. lugdunensis virulence suggesting the occurrence of several genetic recombination’ with other staphylococci.