Update on clinical significance of coagulase-negative staphylococci

Phylogenetic relationships among Staphylococcus species and refinement of cluster groups based on multilocus data

Background

Estimates of relationships among Staphylococcus species have been hampered by poor and inconsistent resolution of phylogenies based largely on single gene analyses incorporating only a limited taxon sample. As such, the evolutionary relationships and hierarchical classification schemes among species have not been confidently established. Here, we address these points through analyses of DNA sequence data from multiple loci (16S rRNA gene, dnaJ, rpoB, and tuf gene fragments) using multiple Bayesian and maximum likelihood phylogenetic approaches that incorporate nearly all recognized Staphylococcus taxa.

Results

We estimated the phylogeny of fifty-seven Staphylococcus taxa using partitioned-model Bayesian and maximum likelihood analysis, as well as Bayesian gene-tree species-tree methods. Regardless of methodology, we found broad agreement among methods that the current cluster groups require revision, although there was some disagreement among methods in resolution of higher order relationships. Based on our phylogenetic estimates, we propose a refined classification for Staphylococcus with species being classified into 15 cluster groups (based on molecular data) that adhere to six species groups (based on phenotypic properties).

Conclusions

Our findings are in general agreement with gene tree-based reports of the staphylococcal phylogeny, although we identify multiple previously unreported relationships among species. Our results support the general importance of such multilocus assessments as a standard in microbial studies to more robustly infer relationships among recognized and newly discovered lineages.

Central venous catheter-related bloodstream infections in the intensive care unit

CONTEXT

Central venous catheter-related bloodstream infection (CRBSI) is associated with high rates of morbidity and mortality in critically ill patients.

AIMS

This study was conducted to determine the incidence of central venous catheter-related infections (CRIs) and to identify the factors influencing it. So far, there are very few studies that have been conducted on CRBSI in the intensive care unit in India.

SETTINGS AND DESIGN

This was a prospective, observational study carried out in the medical intensive care unit (MICU) over a period of 1 year from January to December 2004.

MATERIALS AND METHODS

A total of 54 patients with indwelling central venous catheters of age group between 20 and 75 years were included. The catheters were cultured using the standard semiquantitative culture (SQC) method. Statistical analysis used SPSS-10 version statistical software.

RESULTS

A total of 54 CVC catheters with 319 catheter days were included in this study. Of 54 patients with CVCs studied for bacteriology, 39 (72.22%) catheters showed negative SQCs and also negative blood cultures. A total of 15 (27.77%) catheters were positive on SQC, of which 10 (18.52%) were with catheter-associated infection and four (7.41%) were with catheter-associated bacteremia; the remaining one was a probable catheter-associated bacteremia. CRIs were high among catheters that were kept in situ for more than 3 days and emergency procedures where two or more attempts were required for catheterization (P < 0.05). In multivariate analysis of covariance duration of catheter in situ for >3 days, inexperienced venupucturist, more number of attempts and emergency CVC were associated with more incidence of CVCBSIs, with P <0.02. The duration of catheter in situ was negatively correlated (-0.53) and number of attempts required to put CVC was positively correlated (+0.39) with incidence of CVCBSIs. Sixty-five percent of the isolates belonged to the CONS group (13/20). Staphylococcus epidermidis showed maximum susceptibility to amikacin, doxycycline and amoxycillin with clavulanic acid and was susceptible to vancomycin (100%). Klebsiella pneumoniae was 100% susceptible to amikacin and ciprofloxacin. Escherichia coli was susceptible to amikacin and cefotaxime.

CONCLUSIONS

The overall incidence of CRI was 27.77% (15/54). Catheter-associated BSIs were 47.31 per 1000 catheter-days. CRI was low in the catheters inserted by the experienced venipuncturists, elective procedure and CVC kept in situ for ≤3 days. S. epidermidis was the most common isolate.

Nasal carriage of Staphylococcus schleiferi from healthy dogs and dogs with otitis, pyoderma or both

In veterinary medicine, Staphylococcus schleiferi was previously assumed to be an inhabitant of carnivore skin, however, more recently, it has been repeatedly documented in the literature as both an inhabitant and as a pathogen. In order to determine the frequency of nasal carriage, and the methicillin susceptibility pattern of S. schleiferi from healthy dogs as well as dogs with otitis and/or pyoderma, a prospective study including 24 dogs with healthy ears and skin, 27 dogs with healthy ears and pyoderma, 15 dogs with otitis without pyoderma and 20 dogs with both otitis and pyoderma was performed. Specimens were obtained and cultured and isolates were identified as S. schleiferi based on growth and biochemical characteristics. S. schleiferi was isolated from the nares of 1 healthy dog, 3 dogs with recurrent pyoderma, 2 dogs with recurrent otitis, and 1 dog with both recurrent otitis and pyoderma. One of the S. schleiferi isolates was methicillin resistant. Nasal carriage of S. schleiferi does occur in healthy dogs as well as dogs with otitis and pyoderma. Methicillin resistant and sensitive S. schleiferi can be found in the nares of dogs with diseased ears and skin.

Surgical glove bacterial contamination and perforation during total hip arthroplasty implantation: when gloves should be changed

INTRODUCTION

Double gloving is recommended in orthopedic surgery, notably in total hip arthroplasties (THA) to prevent contamination of the surgical site.

HYPOTHESIS

Systematic glove changes during the key phases of hip prosthesis implantation reduce the frequency of occult perforations and bacterial loading of glove surfaces.

PATIENTS AND METHODS

During 29 THA implantation procedures, we evaluated the bacterial contamination of the outer glove surface and its perforation rate. Contaminations were sought by placing the gloved fingertips on blood geloses (incubation, 48 h at 37°C), and perforations were sought using a water test (NF EN 455-1).

RESULTS

One intervention was excluded from the study because an initial contamination was detected, leaving 28 cases analyzed. Fifteen interventions (53.6%) presented contaminated geloses (26 contaminated glove changes for 3.38% of the gloves used). These contaminations were found on the gloves of all of the gloved personnel, with no distinction as to the right or left side. Thirty-eight percent of the contaminations occurred during joint reduction, whereas the other surgical stages grouped 15-26% of the contaminations (P<0.05). Twenty-nine bacteria were identified: 62% coagulase-negative staphylococci (16% of which were methicillin-resistant). Twenty-eight perforations were identified (3.5% of the gloves used), 67.8% of which were located on the operator and 64.3% on the dominant side. Eighty percent of the perforations occurred during the "surgical incision" and the "cup and stem implantation" stages (respectively, 5.0% and 5.5% of the gloves used during the surgical time) (P<0.05), without being associated with an increased risk of bacterial contamination. At the 12-month clinical follow-up, no infectious complications were found. On the gloves worn by the 20 surgical team members contaminated during these 28 surgical procedures, replacing contaminated gloves with new sterile gloves rendered all the bacteriological samples of the subsequent surgical stages negative in 16 cases (80%).

DISCUSSION

Increasing the number of outer glove renewals, notably during certain surgical stages at risk for contamination (prosthesis reduction) or perforation (surgical incision/femoral cementing) can reduce the risk of contamination and perforation. The bacteria isolated suggest a cutaneous origin. Regularly changing gloves has resulted in a sterile state in 80% of cases. LEVEL OF EVIDENCE AND TYPE OF STUDY: Level III prospective diagnostic study.

Combined effect of enterocin and lipase from Enterococcus faecium NCIM5363 against food borne pathogens: mode of action studies

Food borne diseases have a major impact on public health whose epidemiology is rapidly changing. The whole cells of pathogens involved or their toxins/metabolites affect the human health apart from spoiling sensory properties of the food products finally affecting the food industry as well as consumer health. With pathogens developing mechanisms of antibiotic resistance, there has been an increased need to replace antibiotics as well as chemical additives with naturally occurring bacteriocins. Bacteriocins are known to act mainly against Gram-positive pathogens and with little or no effect towards Gram-negative enteric bacteria. In the present study, combination effect of lipase and bacteriocin produced by Enterococcus faecium NCIM5363, a highly lipolytic lactic acid bacterium against various food pathogens was assessed. The lipase in combination with enterocin exhibited a lethal effect against Gram-negative pathogens. Scanning electron microscopy studies carried out to ascertain the constitutive mode of action of lipase and enterocin revealed that the lipase degrades the cell wall of Gram-negative bacteria and creates a pore through which enterocin enters thereby resulting in cell death. The novelty of this work is the fact that this is the first report revealing the synergistic effect of lipase with enterocin against Gram-negative bacteria.

The iron-regulated staphylococcal lipoproteins

Lipoproteins fulfill diverse roles in antibiotic resistance, adhesion, protein secretion, signaling and sensing, and many also serve as the substrate binding protein (SBP) partner to ABC transporters for the acquisition of a diverse array of nutrients including peptides, sugars, and scarcely abundant metals. In the staphylococci, the iron-regulated SBPs are significantly upregulated during iron starvation and function to sequester and deliver iron into the bacterial cell, enabling staphylococci to circumvent iron restriction imposed by the host environment. Accordingly, this subset of lipoproteins has been implicated in staphylococcal pathogenesis and virulence. Lipoproteins also activate the host innate immune response, triggered through Toll-like receptor-2 (TLR2) and, notably, the iron-regulated subset of lipoproteins are particularly immunogenic. In this review, we discuss the iron-regulated staphylococcal lipoproteins with regard to their biogenesis, substrate specificity, and impact on the host innate immune response.

Antistaphylococcal activity of bacteriophage derived chimeric protein P128

Background

Bacterial drug resistance is one of the most significant challenges to human health today. In particular, effective antibacterial agents against methicillin-resistant Staphylococcus aureus (MRSA) are urgently needed. A causal relationship between nasal commensal S. aureus and infection has been reported. Accordingly, elimination of nasal S. aureus reduces the risk of infection. Enzymes that degrade bacterial cell walls show promise as antibacterial agents. Bacteriophage-encoded bacterial cell wall-degrading enzymes exhibit intrinsic bactericidal activity. P128 is a chimeric protein that combines the lethal activity of the phage tail-associated muralytic enzyme of Phage K and the staphylococcal cell wall targeting-domain (SH3b) of lysostaphin.

Here we report results of in vitro studies evaluating the susceptibility of staphylococcal strains to this novel protein.

Results

Using the broth microdilution method adapted for lysostaphin, we found that P128 is effective against S. aureus clinical strains including MRSA, methicillin-sensitive S. aureus (MSSA), and a mupirocin-resistant S. aureus. Minimum bactericidal concentrations and minimum inhibitory concentrations of P128 (1-64 μg/mL) were similar across the 32 S. aureus strains tested, demonstrating its bactericidal nature.

In time-kill assays, P128 reduced colony-forming units by 99.99% within 1 h and inhibited growth up to 24 h.

In an assay simulating topical application of P128 to skin or other biological surfaces, P128 hydrogel was efficacious when layered on cells seeded on solid media. P128 hydrogel was lethal to Staphylococci recovered from nares of healthy people and treated without any processing or culturing steps, indicating its in situ efficacy. This methodology used for in vitro assessment of P128 as an agent for eradicating nasal carriage is unique.

Conclusions

The novel chimeric protein P128 is a staphylococcal cell wall-degrading enzyme under development for clearance of S. aureus nasal colonization and MRSA infection. The protein is active against globally prevalent antibiotic-resistant clinical isolates and other clinically significant staphylococcal species including S. epidermidis. The P128 hydrogel formulation was bactericidal against Staphylococci including S. aureus recovered from the nares of 31 healthy people, demonstrating its in situ efficacy.

Evaluation of pet contact as a risk factor for carriage of multidrug-resistant staphylococci in nursing home residents

BACKGROUND

Pets, often used as companionship and for psychological support in the therapy of nursing home residents, have been implicated as reservoirs for antibiotic-resistant bacteria. We investigated the importance of pets as reservoirs of multidrug-resistant (MDR) staphylococci in nursing homes.

METHODS

We assessed the carriage of MDR staphylococci in pets and in 2 groups of residents, those living in nursing homes with pets and those living without pet contacts. We collected demographic, health status, and human-pet contact data by means of questionnaires. We assessed potential bacteria transmission pathways by investigating physical resident-to-pet contact.

RESULTS

The observed prevalence of MDR staphylococci carriage was 84/229 (37%) in residents living with pets and 99/216 (46%) in those not living with pets (adjusted odds ratio [aOR], 0.6; 95% confidence interval [CI], 0.4-0.9). Active pet contact was associated with lower carriage of MDR staphylococci (aOR, 0.5; 95% CI, 0.4-0.8). Antibiotic treatment during the previous 3 months was associated with significantly increased risk for MDR carriage in residents (aOR, 3.1; 95% CI, 1.8-5.7).

CONCLUSIONS

We found no evidence that the previously reported benefits of pet contact are compromised by the increased risk of carriage of MDR staphylococci in residents associated with interaction with these animals in nursing homes. Thus, contact with pets, always under good hygiene standards, should be encouraged in these settings.

Comparative genomic analysis of the genus Staphylococcus including Staphylococcus aureus and its newly described sister species Staphylococcus simiae

Background

Staphylococcus belongs to the Gram-positive low G + C content group of the Firmicutes division of bacteria. Staphylococcus aureus is an important human and veterinary pathogen that causes a broad spectrum of diseases, and has developed important multidrug resistant forms such as methicillin-resistant S. aureus (MRSA). Staphylococcus simiae was isolated from South American squirrel monkeys in 2000, and is a coagulase-negative bacterium, closely related, and possibly the sister group, to S. aureus. Comparative genomic analyses of closely related bacteria with different phenotypes can provide information relevant to understanding adaptation to host environment and mechanisms of pathogenicity.

Results

We determined a Roche/454 draft genome sequence for S. simiae and included it in comparative genomic analyses with 11 other Staphylococcus species including S. aureus. A genome based phylogeny of the genus confirms that S. simiae is the sister group to S. aureus and indicates that the most basal Staphylococcus lineage is Staphylococcus pseudintermedius, followed by Staphylococcus carnosus. Given the primary niche of these two latter taxa, compared to the other species in the genus, this phylogeny suggests that human adaptation evolved after the split of S. carnosus. The two coagulase-positive species (S. aureus and S. pseudintermedius) are not phylogenetically closest but share many virulence factors exclusively, suggesting that these genes were acquired by horizontal transfer. Enrichment in genes related to mobile elements such as prophage in S. aureus relative to S. simiae suggests that pathogenesis in the S. aureus group has developed by gene gain through horizontal transfer, after the split of S. aureus and S. simiae from their common ancestor.

Conclusions

Comparative genomic analyses across 12 Staphylococcus species provide hypotheses about lineages in which human adaptation has taken place and contributions of horizontal transfer in pathogenesis.

Comparative study using phenotypic, genotypic, and proteomics methods for identification of coagulase-negative staphylococci

Five methods were compared to determine the most accurate method for identification of coagulase-negative staphylococci (CoNS) (n = 142 strains). Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) showed the best results for rapid and accurate CoNS differentiation (99.3% of strains correctly identified). An alternative to this approach could be Vitek2 combined with partial tuf gene sequencing (100% of strains correctly identified when both methods are performed simultaneously).

Detection of macrolide and disinfectant resistance genes in clinical Staphylococcus aureus and coagulase-negative staphylococci

Background

Staphylococcus aureus and Coagulase-negative staphylococci (CoNS) are a major source of infections associated with indwelling medical devices. Many antiseptic agents are used in hygienic handwash to prevent nosocomial infections by Staphylococci. Our aim was to determine the antibiotic susceptibility and resistance to quaternary ammonium compound of 46 S. aureus strains and 71 CoNS.

Methods

S. aureus (n = 46) isolated from auricular infection and CoNS (n = 71), 22 of the strains isolated from dialysis fluids and 49 of the strains isolated from needles cultures were investigated. Erythromycin resistance genes (ermA, ermB, ermC, msrA and mef) were analysed by multiplex PCR and disinfectant-resistant genes (qacA, qacB, and qacC) were studied by PCR-RFLP.

Results

The frequency of erythromycin resistance genes in S. aureus was: ermA+ 7.7%, ermB+ 13.7%, ermC+ 6% and msrA+ 10.2%. In addition, the number of positive isolates in CoNS was respectively ermA+ (9.4%), ermB+ (11.1%), ermC+ (27.4%), and msrA+ (41%). The MIC analyses revealed that 88 isolates (74%) were resistant to quaternary ammonium compound-based disinfectant benzalkonium chloride (BC). 56% of the BC-resistant staphylococcus isolates have at least one of the three resistant disinfectants genes (qacA, qacB and qacC). Nine strains (7.7%) among the CoNS species and two S. aureus strains (2%) harboured the three-qac genes. In addition, the qacC were detected in 41 strains.

Conclusions

Multi-resistant strains towards macrolide and disinfectant were recorded. The investigation of antibiotics and antiseptic-resistant CoNS may provide crucial information on the control of nosocomial infections.

Genotypes, antibiotic resistance, and virulence factors of staphylococci from ready-to-eat food

Sixty-seven staphylococcal isolates belonging to 12 species were obtained from 70 ready-to-eat food products. Staphylococcus aureus (n=25), and Staphylococcus epidermidis (n=13) were dominant. Susceptibility to penicillin, oxacillin, tetracycline, clindamycin, gentamicin, erythromycin, ciprofloxacin, and vancomycin was determined. All investigated S. aureus isolates were resistant to at least one antibiotic, and fifteen isolates were resistant to four and more antibiotics. Thirty-eight coagulase-negative staphylococci (CNS) isolates were resistant to at least one antibiotic, and seventeen to four and more antibiotics. Fifteen CNS isolates were mecA positive, and grew in the presence of 6 μg/mL oxacillin. All S. aureus isolates were mecA-negative. Arginine catabolic mobile element (ACME) was found in seven S. epidermidis isolates. Five S. epidermidis isolates harbored ica operon, ACME and were able to form biofilm. Three of them also possessed IS256 element and were mecA-positive. The expression of icaA gene was comparable in five ica-positive S. epidermidis isolates. One of six mecA positive S. epidermidis isolates was classified as sequence type (ST)155, one as ST110, and two as ST88. Two methicillin-resistant Staphylococcus epidermis (MRSE) belonged to new STs, that is, ST362, and ST363. Enterotoxin genes were found in 92% of S. aureus isolates. No enterotoxin gene was detected in analyzed CNS population. We show that ready-to-eat products are an important source of antibiotic-resistant CNS and potentially virulent strains of S. epidermidis, including genotypes undistinguishable from hospital-adapted clones.

Distribution of erm genes and low prevalence of inducible resistance to clindamycin among staphylococci isolates

INTRODUCTION

Resistance to macrolides, lincosamides and streptogramins B (MLS(B) antibiotics) in staphylococci may be due to modification in ribosomal target methylase encoded by erm genes. The expression of MLS(B) resistance lead to three phenotypes, namely constitutive resistance (cMLS(B)), inducible resistance (iMLS(B)), and resistance only to macrolides and streptogramins B (MS(B)). The iMLS(B) resistance is the most difficult to detect in the clinical laboratory.

OBJECTIVE

This study investigated the expression of MLS(B) resistance and the prevalence of the erm genes among 152 clinical isolates of Staphylococcus aureus and coagulase-negative Staphylococcus (CNS) from Hospital de Clínicas de Porto Alegre.

METHODS

Primary MLS(B) resistance was detected by the disk diffusion method. Isolates with iMLS(B) phenotype were tested by double-disk induction method. All isolates were tested by a genotypic assay, PCR with specific primers.

RESULTS

A total of 46.7% of staphylococci were positive for cMLS(B); 3.3% for iMLS(B) and 3.3% for MS(B). One or more erm genes were present in 50.1% of isolates. The gene ermA was detected in 49 isolates, ermC in 29 and ermB in 3.

CONCLUSION

The prevalence of the ermA, ermB and ermC genes were 29.6%, 17.1% and 0.66% respectively, and constitutive resistance was the most frequent as compared to the other two phenotypes.

Double triplex real-time PCR assay for simultaneous detection of Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus hominis, and Staphylococcus haemolyticus and determination of their methicillin resistance directly from positive blood culture bottles

We developed and validated here a double triplex real-time PCR assay to simultaneously detect and identify Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus hominis, Staphylococcus haemolyticus and their methicillin resistance in a single reaction directly from Gram-positive cocci-in-clusters (GPCs)-positive blood culture bottles. From August 15, 2009 through February 15, 2010, 238 GPC-positive samples were collected and identified by conventional methods as 11 methicillin-resistant S. aureus (MRSA), 28 methicillin-susceptible S. aureus (MSSA), 176 MR coagulase-negative staphylococci (MRCoNS), 21 MSCoNS and two Enterococcus faecalis. The double triplex real-time PCR assay was targeted and detected tuf, nuc and mecA genes in the first tube and atlE, gap and mvaA genes in the second tube which could be run simultaneously. The detection limit of the assay was found at 10(3) CFU/ml for the atleE gene, 10(4) CFU/ml for the mva gene and 10(5) CFU/ml for gap, nuc, mecA and tuf genes based on seeding experiments. All Staphylococcus species except two S. epidermidis were correctly identified by the assay. The double triplex real-time PCR assay quickly and accurately detects S. aureus, S. epidermidis, S. hominis and S. haemolyticus and their methicillin resistance in a single reaction directly from positive blood culture bottles within 83 min.

Chinks in the armor: the role of the nonclinical environment in the transmission of Staphylococcus bacteria

The staphylococci include bacteria species and strains that are capable of causing significant infections in humans. During the past decades, staphylococci, such as methicillin-resistant S aureus (MRSA), have emerged outside the nosocomial settings, spreading in the community and raising public health concerns. However, the full contribution of potential community reservoirs to the changing epidemiology of these pathogens remains largely uncharacterized. Here, it is suggested that the role of animals (pets and livestock) and inanimate surfaces in the dissemination of staphylococci in the community is worthy of investigation and might potentially enhance efforts for controlling Staphylococcus-associated infections in susceptible individuals.

Cross-sectional study of antimicrobial-resistant bacteria in horses. Part 1: Prevalence of antimicrobial-resistant Escherichia coli and methicillin-resistant Staphylococcus aureus

REASONS FOR PERFORMING STUDY

The increasing prevalence of antimicrobial-resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA) and antimicrobial-resistant Escherichia coli represents a significant problem. However, the carriage of such bacteria by horses in the UK has not been well characterised.

OBJECTIVES

To estimate the prevalence of nasal carriage of MRSA and faecal carriage of antimicrobial-resistant E. coli amongst horses in the general equine community of the mainland UK.

METHODS

A cross-sectional study of horses recruited by 65 randomly selected equine veterinary practices was conducted, with nasal swabs and faecal samples collected. Faecal samples were cultured for antimicrobial-resistant E. coli. Nasal swabs were cultured for staphylococcal species; methicillin-resistant isolates identified as S. aureus were characterised by SCCmec and spa gene typing. Multilevel logistic regression models were used to calculate prevalence estimates with adjustment for clustering at practice and premises levels. Spatial variation in risk of antimicrobial resistance was also examined.

RESULTS

In total, 650 faecal samples and 678 nasal swabs were collected from 692 horses located on 525 premises. The prevalence of faecal carriage of E. coli with resistance to any antimicrobial was 69.5% (95% CI 65.9-73.1%) and the prevalence of extended-spectrum β-lactamase (ESBL)-producing E. coli was 6.3% (95% CI 4.1-9.6%). The prevalence of nasal carriage of MRSA was 0.6% (95% CI 0.2-1.5%). Spatial analysis indicated variation across the UK for risk of carriage of resistant and multidrug-resistant (resistant to more than 3 antimicrobial classes) E. coli.

CONCLUSIONS AND POTENTIAL RELEVANCE

Carriage of MRSA by horses in the community appears rare, but the prevalence of antimicrobial-resistant E. coli (including ESBL-producing E. coli) is higher. A high prevalence of antimicrobial-resistant bacteria could have significant health implications for the horse population of the UK.

Molecular detection of enterotoxins E, G, H and I in Staphylococcus aureus and coagulase-negative staphylococci isolated from clinical samples of newborns in Brazil

AIMS

The objective of this study was to investigate the detection of SEE, SEG, SEH and SEI in strains of Staphylococcus aureus and coagulase-negative staphylococci (CNS) using RT-PCR.

METHODS AND RESULTS

In this study, 90 Staph. aureus strains and 90 CNS strains were analysed by PCR for the detection of genes encoding staphylococcal enterotoxins (SE) E, G, H and I. One or more genes were detected in 54 (60%) Staph. aureus isolates and in 29 (32.2%) CNS isolates. Staphylococcus epidermidis was the most frequently isolated CNS species (n = 64, 71.1%), followed by Staphylococcus warneri (n = 8, 8.9%) and other species (Staphylococcus haemolyticus, Staphylococcus hominis, Staphylococcus lugdunensis, Staphylococcus simulans, Staphylococcus saprophyticus and Staphylococcus xylosus: n = 18, 20%). The genes studied were detected in Staph. epidermidis, Staph. warneri, Staph. haemolyticus, Staph. hominis, Staph. simulans and Staph. lugdunensis. The highest frequency of genes was observed in Staph. epidermidis and Staph. warneri, a finding indicating differences in the pathogenic potential between CNS species and highlighting the importance of the correct identification of these micro-organisms. RT-PCR used for the detection of mRNA revealed the expression of SEG, SEH and/or SEI in 32 (59.3%) of the 90 Staph. aureus isolates, whereas expression of some of these genes was observed in 10 (34.5%) of the 90 CNS isolates.

CONCLUSIONS

Staphylococcus epidermidis was the most toxigenic CNS species. Among the other species, only Staph. warneri and Staph. lugdunensis presented a positive RT-PCR result. PCR was efficient in confirming the toxigenic capacity of Staph. aureus and CNS.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study permitted to confirm the toxigenic capacity of CNS to better characterize the pathogenic potential of this group of micro-organisms. In addition, it permitted the detection of SEG, SEH and SEI, enterotoxins that cannot be detected by commercially available immunological methods.

Identification of Coagulase-Negative Staphylococci Isolated from Continuous Ambulatory Peritoneal Dialysis Fluid using 16s Ribosomal RNA, tuf, and SodA Gene Sequencing

Introduction

Coagulase-negative staphylococcus (CoNS) is the most common pathogen in continuous ambulatory peritoneal dialysis (CAPD)–associated peritonitis. There is no well-organized, standardized database for CoNS, and few studies have used gene sequencing in reporting species distribution in CAPD peritonitis. In the present study, we used 3 housekeeping genes to evaluate the prevalence of CoNS isolated from CAPD peritonitis episodes and to estimate the accuracy of, and the characteristic differences between, these genes for species identification.

Methods

All 51 non-duplicated CoNS isolates obtained from CAPD peritonitis between April 2006 and May 2008 were used. The strains were identified by polymerase chain reaction and by direct sequencing using the 16S ribosomal RNA (rRNA), tuf, and sodA genes. We determined species distribution, and using selected databases, we analyzed the characteristics and diagnostic utility of the individual genes for species identification.

Results

In GenBank (National Institutes of Health, Bethesda, MD, USA), we found 49 type or reference strains for CoNS 16S rRNA, 17 for tuf, and 46 for sodA, and we used those data for sequence-similarity comparisons with CAPD isolates. Among our 51 strains, S. epidermidis (66.7%) was the most common, followed by S. haemolyticus (11.8%), S. warneri (7.8%), S. caprae (5.9%), S. capitis (3.9%), and S. pasteuri (2.0%). For 1 strain, different species results were obtained with each gene. The identification rates with 16S rRNA, sodA, and tuf gene sequencing were 84.0%, 96.0%, and 92.2% respectively. The discrimination capability of 16S rRNA gene was lower in a few individual species, and for the sodA gene, the percentage similarity to sequences from reference strains was also lower. The tuf gene had excellent identification capacity, but relatively few type strains are available in public databases. The 16S rRNA gene did not discriminate between S. caprae and S. capitis. The sodA gene showed a similarity rate that was lower than that for sequences of the 16S rRNA gene. The tuf type strain sequences for S. caprae and S. pasteuri are not available in public databases.

Conclusions

The sodA, tuf, and 16S rRNA genes were very useful for CoNS identification. Each has its own characteristics of similarity, discriminative power, and inclusion in databases.

Epidemiology and virulence insights from MRSA and MSSA genome analysis

Staphylococcus aureus is a major human pathogen responsible for a wide diversity of infections ranging from localized to life threatening diseases. From 1961 and the emergence of methicillin-resistant S. aureus (MRSA), this bacterium has shown a particular capacity to survive and adapt to drastic environmental changes and since the beginning of the 1990s it has spread worldwide. Until recently, S. aureus was considered as the prototype of a nosocomial pathogen but it has now been recognized as an agent responsible for outbreaks in the community. Several recent reports suggest that the epidemiology of MRSA is changing. Understanding of pathogenicity, virulence and emergence of epidemic clones within MRSA populations is not clearly defined, despite several attempts to identify common molecular features between strains that share similar epidemiological and/or virulence behavior. These studies included: pattern profiling of bacterial adhesins, analysis of clonal complex groups, molecular genotyping and enterotoxin content analysis. To date, all approaches failed to find a correlation between molecular determinants and clinical outcomes. We hypothesize that the capacity of the bacterium to become more invasive or virulent is determined by genetics. The utilization of massively parallel methods of analysis is therefore ideal to study the contribution of genetics. Therefore, this article focuses on the entire genome including coding sequences as well as noncoding sequences. This high resolution approach allows the monitoring micro- and macroevolution of MRSA and identification of specific genomic markers of evolution of invasive or highly virulent phenotypes.

Detection and differentiation of staphylococcal contamination of clinical surfaces using denaturing gradient gel electrophoresis

The detection and identification of staphylococci from the environment of at-risk patients can be an important step in determining the role of the environment in hospital-acquired infections. Current methods that are used to identify these pathogens are either limited in their capabilities, expensive and/or labour intensive. We developed a denaturing gradient gel electrophoresis (DGGE) analysis protocol for the detection and identification of staphylococci that takes advantage of species-specific polymorphisms in the gene that encodes elongation factor Tu (tuf). The protocol was optimised by performing polymerase chain reaction (PCR)-DGGE analysis on DNA isolated from pure cultures of 27 different staphylococcal species. This resulted in the separation of the PCR products into 19 different band positions, including unique positions for important species such as Staphylococcus aureus, S. hominis, S. lugdunensis, S. warneri, S. capitis, S. caprae and S. saprophyticus. Application of the method was demonstrated by swabbing 15 clinical surfaces in an isolation room occupied by a patient before and after routine cleaning. PCR-DGGE analysis of tuf showed that despite cleaning efforts, the surfaces remained contaminated with several species of staphylococci, including S. aureus, S. epidermidis, S. lugdunensis, S. hominis, S. haemolyticus and S. simulans. We conclude that DGGE of tuf represents a promising technique for the detection, characterisation and monitoring of mixed assemblages of staphylococci in the healthcare environment.

Identification of staphylococci by Phoenix: validation of a new protocol and comparison with Vitek 2

Because of their frequent isolation in the routine laboratory and their increasing clinical significance, fast and accurate species identification of staphylococci may be required; this can only be achieved by automated systems. A total of 147 clinical isolates (52 Staphylococcus aureus, 50 Staphylococcus epidermidis, and 45 other coagulase-negative staphylococci [CoNS]) were first identified by molecular methodology and then comparatively tested by Vitek 2 (new colorimetric identification card) and Phoenix using the novel 0.25 McFarland and the standard 0.50 McFarland inoculum protocols. All S. aureus isolates were accurately identified. Vitek 2 identified correctly all S. epidermidis and 93.3% of the other CoNS, whereas the respective rates were 86% and 82.2% for Phoenix's standard and 92% and 82.2% for the novel protocol. It appears that both systems provide excellent identification of S. aureus, but Vitek 2 recognizes CoNS species more accurately than Phoenix. The 0.25 McFarland protocol does not improve system performance.

Amino acid residues modulating the activities of staphylococcal glutamyl endopeptidases

The glutamyl endopeptidase family of enzymes from staphylococci has been shown to be important virulence determinants of pathogenic family members, such as Staphylococcus aureus. Previous studies have identified the N-terminus and residues from positions 185-195 as potentially important regions that determine the activity of three members of the family. Cloning and sequencing of the new family members from Staphylococcus caprae (GluScpr) and Staphylococcus cohnii (GluScoh) revealed that the N-terminal Val residue is maintained in all family members. Mutants of the GluV8 enzyme from S. aureus with altered N-terminal residues, including amino acids with similar properties, were inactive, indicating that the Val residue is specifically required at the N-terminus of this enzyme family in order for them to function correctly. Recombinant GluScpr was found to have peptidase activity intermediate between GluV8 and GluSE from Staphylococcus epidermis and to be somewhat less specific in its substrate requirements than other family members. The 185-195 region was found to contribute to the activity of GluScpr, although other regions of the enzyme must also play a role in defining the activity. Our results strongly indicate the importance of the N-terminal and the 185-195 region in the activity of the glutamyl endopeptidases of staphylococci.

Prevalence and characteristics of methicillin-resistant coagulase-negative staphylococci from livestock, chicken carcasses, bulk tank milk, minced meat, and contact persons

Background

Methicillin-resistant coagulase-negative staphylococci (MR-CNS) are of increasing importance to animal and public health. In veterinary medicine and along the meat and milk production line, only limited data were so far available on MR-CNS characteristics. The aim of the present study was to evaluate the prevalence of MR-CNS, to identify the detected staphylococci to species level, and to assess the antibiotic resistance profiles of isolated MR-CNS strains.

Results

After two-step enrichment and growth on chromogenic agar, MR-CNS were detected in 48.2% of samples from livestock and chicken carcasses, 46.4% of samples from bulk tank milk and minced meat, and 49.3% of human samples. Using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), 414 selected MR-CNS strains belonged to seven different species (S. sciuri, 32.6%; S. fleurettii, 25.1%; S. haemolyticus, 17.4%; S. epidermidis, 14.5%, S. lentus, 9.2%; S. warneri, 0.7%; S. cohnii, 0.5%). S. sciuri and S. fleurettii thereby predominated in livestock, BTM and minced meat samples, whereas S. epidermidis and S. haemolyticus predominated in human samples. In addition to beta-lactam resistance, 33-49% of all 414 strains were resistant to certain non-beta-lactam antibiotics (ciproflaxacin, clindamycin, erythromycin, tetracycline).

Conclusions

A high prevalence of MR-CNS was found in livestock production. This is of concern in view of potential spread of mecA to S. aureus (MRSA). Multiresistant CNS strains might become an emerging problem for veterinary medicine. For species identification of MR-CNS isolated from different origins, MALDI-TOF MS proved to be a fast and reliable tool and is suitable for screening of large sample amounts.

Slime production is essential for the adherence of Staphylococcus epidermidis in implant-related infections

A total of 32 Staphylococcus epidermidis isolates from indwelling device-related infections such as endophthalmitis following intraocular lens (IOL) implantation, intravenous catheter-related sepsis and orthopaedic implant infections, were studied for slime production and adherence to artificial surfaces. Of these, 21 (65.6%) isolates were slime positive by the Congo Red agar method and 24 (75%) were adherent to artificial surfaces by the quantitative slime test. The majority (19 out of 24; 79.1%) of the adherent bacteria were slime producers. Antibody to slime raised in rabbits was able to inhibit the adherence of all 24 bacteria designated as adherent by our quantitative test. It seems that slime is indispensable for the sessile mode of attachment, leading further to the development of biofilms on the indwelling devices.

Hospital epidemiology and infection control in acute-care settings

Health care-associated infections (HAIs) have become more common as medical care has grown more complex and patients have become more complicated. HAIs are associated with significant morbidity, mortality, and cost. Growing rates of HAIs alongside evidence suggesting that active surveillance and infection control practices can prevent HAIs led to the development of hospital epidemiology and infection control programs. The role for infection control programs has grown and continues to grow as rates of antimicrobial resistance rise and HAIs lead to increasing risks to patients and expanding health care costs. In this review, we summarize the history of the development of hospital epidemiology and infection control, common HAIs and the pathogens causing them, and the structure and role of a hospital epidemiology and infection control program.

Prevalence, aetiology and antibiotic resistance profiles of coagulase negative staphylococci isolated in a teaching hospital

In this paper we carried out a study about prevalence of the clinically significant coagulase negative staphylococcal (CNS) isolates found in an university hospital. Two hundred four CNS isolates from 191 patients obtained between the period of 1998 to 2002, were studied. About 27% (52/191) of the infection cases studied were confirmed as CNS-associated diseases. Blood stream infection (BSI) was the most frequent CNS associated-disease (25%; 13/52). The great majority of the BSI was verified in the Neonatal Intensive Care Unit (NICU). The analysis of the 52 patients medical history showed that 85% of the BSI was acquired in hospital. Most of the CNS nosocomial infections were associated with the use of indwelling medical devices. The incidence of methicillin-resistance among significant CNS isolates was 38%. In this study, a high percentage of exogenous contaminant was verified (60%), indicating that contamination of clinical specimens during sample collection is critical.

Polymerase chain reaction detection of enterotoxins genes in coagulase-negative staphylococci isolated from Brazilian Minas cheese

For a long time, Staphylococcus aureus has been always thought to be the only pathogenic species among Staphylococcus, while coagulase-negative staphylococci (CNS) were classified as contaminant agents. However, molecular techniques have shown that these microorganisms also possess enterotoxin-encoding genes. The aim of this study was to analyze the frequency of genes for staphylococcal enterotoxins SEA, SEB, SEC, and SED in CNS strains isolated from Minas soft cheese and to assess the in vitro production of toxins. CNS were found in 65 (72.2%) samples of cheese: 23 were Staphylococcus saprophyticus, 16 Staphylococcus warneri, 10 Staphylococcus epidermidis, 9 Staphylococcus xylosus, 3 Staphylococcus haemolyticus, 2 Staphylococcus schleiferi subsp. schleiferi, and 1 each Staphylococcus capitis subsp. urealyticus and Staphylococcus caprae. Seventeen (26.2%) CNS strains had genes for enterotoxins, and sea was more frequently found (18.5%), followed by sec in three and seb in two strains, whereas the sed gene was not found. S. saprophyticus showed enterotoxin genes in 6 of 23 isolates, but only sea was observed. On the other hand, five strains of S. warneri showed the sea, seb, or sec gene. In spite of the presence of these enterotoxin genes, these strains did not produce enterotoxins in vitro. It is essential to understand the real role of CNS in food, and based on the presence of enterotoxin genes, CNS should not be ignored in epidemiological investigations of foodborne outbreaks.

Prevalence of methicillin resistant coagulase negative staphylococci in a tertiary care hospital

BACKGROUND AND OBJECTIVES

Presence of methicillin and multidrug resistance has associated coagulase negative staphylococci (CNS) with high morbidity and mortality worldwide. The present study was carried out to study the susceptibility pattern of CNS to various antimicrobial agents and to determine the prevalence of CNS methicillin resistance in our hospital setting.

MATERIALS AND METHODS

A total of 300 strains of CNS isolated from various clinical specimens were subjected to speciation and their antimicrobial sensitivity testing was studied by Kirby Bauer disc diffusion method. Methicillin resistance was studied by observing minimum inhibitory concentration (MIC) of Oxacillin by macrobroth dilution method and E test. Susceptibility to vancomycin was determined by vancomycin screen agar test and minimum inhibitory concentration by macrobroth dilution test.

RESULTS

All the isolates were susceptible to vancomycin, linezolid and teicoplanin in disc diffusion test while maximum resistance was noted against penicillin (100%) followed by ciprofloxacin (36.3%), norfloxacin (34.3%), gentamicin (34%), nitrofurantoin (29.9%), erythromycin (27.9%) and amikacin (22.7%). Fifty two percent (n = 156) of the isolates were found to be resistant to methicillin. A comparison between resistance patterns of methicilin resistant and methicillin sensitive strains showed that methicillin resistant isolates had higher level of resistance to other antibiotics.

CONCLUSIONS

The high level of resistance among CNS to commonly used antimicrobial agents in our hospital is a matter of great concern and can be prevented by practices of effective infection control measures.

Comparing clinical and microbiological methods for the diagnosis of true bacteraemia among patients with multiple blood cultures positive for coagulase-negative staphylococci

We assessed the accuracy of the Centers for Disease Control and Prevention (CDC) clinical criteria as well as other microbiological methods for the diagnosis of coagulase-negative staphylococci bacteraemia. The CDC clinical criteria had low accuracy, which can be improved by speciation, particularly if the patient had more than two positive blood cultures.

Acceleration of the direct identification of Staphylococcus aureus versus coagulase-negative staphylococci from blood culture material: a comparison of six bacterial DNA extraction methods

To accelerate differentiation between Staphylococcus aureus and coagulase-negative staphylococci (CNS), this study aimed to compare six different DNA extraction methods from two commonly used blood culture materials, i.e. BACTEC and BacT/ALERT. Furthermore, we analysed the effect of reduced blood culture incubation for the detection of staphylococci directly from blood culture material. A real-time polymerase chain reaction (PCR) duplex assay was used to compare the six different DNA isolation protocols on two different blood culture systems. Negative blood culture material was spiked with methicillin-resistant S. aureus (MRSA). Bacterial DNA was isolated with automated extractor easyMAG (three protocols), automated extractor MagNA Pure LC (LC Microbiology Kit M^Grade), a manual kit MolYsis Plus and a combination of MolYsis Plus and the easyMAG. The most optimal isolation method was used to evaluate reduced bacterial incubation times. Bacterial DNA isolation with the MolYsis Plus kit in combination with the specific B protocol on the easyMAG resulted in the most sensitive detection of S. aureus, with a detection limit of 10 CFU/ml, in BacT/ALERT material, whereas using BACTEC resulted in a detection limit of 100 CFU/ml. An initial S. aureus or CNS load of 1 CFU/ml blood can be detected after 5 h of incubation in BacT/ALERT 3D by combining the sensitive isolation method and the tuf LightCycler assay.

An Unusual Presentation of Endocarditis Caused by Staphylococcus warneri

Staphylococcus warneri does not generally cause serious infections in humans. We report a case of endocarditis in a healthy individual with no known past medical history. S. warneri was identified in her blood cultures and echocardiographic evidence confirmed the diagnosis of bacterial endocarditis. There was no apparent cause for her infection, and risk factors such as invasive treatment or medical implant were not present. This rare clinical presentation illustrates the importance of not overlooking low virulence species of Staphylococcus, as they can potentially serve as opportunistic etiological agents for endocarditis, especially among the elderly population.

Staphylococcus warneri meningitis in a patient with Strongyloides stercoralis hyperinfection and lymphoma: first report of a case

A case of meningitis due to Staphylococcus warneri in a patient with a hyperinfection with Strongyloides stercoralis possibly associated with rituximab treatment for mantel cell lymphoma is reported for the first time in the literature. The patient was a 59-year-old woman, with a 3-year history of an apparently well controlled lymphoma after treatment with chemotherapy-immunotherapy and then immunotherapy alone, and diagnosis of strongyloidiasis. Meningitis was diagnosed by cerebrospinal fluid culture and tested with an automated plate system. The patient was successfully treated with vancomycin; although fever and productive cough persisted. Severe gastrointestinal symptoms and pneumonia developed three weeks later. Hyperinfection syndrome by S. stercoralis was diagnosed, with abundant larvae in feces and expectoration.

Resident bacterial flora in the skin of C57BL/6 mice housed under SPF conditions

Research in cutaneous biology frequently involves models that use mice housed in SPF conditions. Little information is available concerning the species of bacteria that normally inhabit the skin of these mice. The aim of this study was to characterize the bacterial skin flora of mice housed under SPF conditions. Skin biopsies from C57BL/6 mice under normal and surgically prepped conditions were both cultured and analyzed by using DNA extraction and sequencing. The species isolated most commonly from culture were staphylococci. Coagulase-negative staphylococci were isolated more frequently than was Staphylococcus aureus. Molecular sequencing yielded several additional organisms not found by culture. Overall, culturing of isolates yielded 14 species of bacteria, and molecular sequencing identified another 6 species. Investigators conducting cutaneous research in mouse models should aware of the cutaneous bacterial flora present on these mice.

Bacterial substitution of coagulase-negative staphylococci for streptococci on the oral mucosa after hematopoietic cell transplantation

PURPOSE

Coagulase-negative staphylococci (CoNS) are frequently isolated from blood cultures of hematopoietic cell transplantation (HCT) patients. Generally, the use of central venous catheters is recognized as a significant risk factor for CoNS infection, while the impact of CoNS infection from oral ulcerative mucositis, which occurs frequently in HCT, may be underestimated. Here, we examined the bacteria on the buccal mucosa after HCT.

METHODS

Sixty-one patients were examined for bacteria on the buccal mucosa routinely once a week from 1 week before to 3 weeks after allogeneic HCT. Subjects were divided into groups with short and long periods of antibiotic use, and differences in bacterial substitution were evaluated. The relationships between type of HCT (conventional HCT or RIST) and bacterial substitution were also evaluated.

RESULTS

The changes in detection frequencies of CoNS and α-streptococci from before to 3 weeks after HCT were significant (P < 0.05, χ (2) test): 14.5-53.3% and 92.7-53.1%, respectively. Significant bacterial substitution of CoNS for streptococci was observed in the long-term antibiotic use group (P < 0.05, χ (2) test), but also occurred in cases with short-term or no antibiotic use. No relationships between type of HCT (conventional HCT or RIST) were observed.

CONCLUSION

Bacterial substitution of CoNS for streptococci occurred frequently on the buccal mucosa after HCT. In addition to antibiotic use, environmental factors may be involved in bacterial substitution. It is important to consider the presence of oral mucositis in CoNS infection after HCT.

Drug susceptibility and clonality of methicillin-resistant Staphylococcus epidermidis in hospitalized patients with hematological malignancies

PURPOSE

To evaluate the clonal relatedness and drug susceptibility of Streptococcus epidermidis isolated from hematological patients.

METHODS

All S. epidermidis isolated from hematological patients who developed bloodstream infections between June 2005 and December 2007 were included. The clonal relationship was tested by means of pulsed-field gel electrophoresis (PFGE) analysis.

RESULTS

Fifteen methicillin-resistant S. epidermidis (MRSE) isolates were examined from patients' blood culture samples. Two subgroups that differed approximately by 40% in their PFGE banding were identified. In clinical practice, two cases were cured with cephalosporin only, thus demonstrating sensitivity of the strains to beta-lactam antibiotics.

CONCLUSIONS

Our results represent two significant findings. One is the major capability of MRSE to colonize patients. The other is that some MRSE isolates proved to be sensitive to clindamycin, minocycline, and cephalosporin, so that using antibiotics to which MRSE is sensitive as first-line therapy can avoid the need for vancomycin in clinical settings.

Antimicrobial resistance and molecular characterization of Staphylococcus haemolyticus in a Chinese hospital

The aim of this study was to perform the molecular characterization of methicillin-resistant Staphylococcus haemolyticus (MRSH) from clinical specimens of patients in a Chinese hospital. One hundred and thirty-three strains of S. haemolyticus collected from April 2002 to April 2003 were analyzed. Antimicrobial susceptibility to 15 antimicrobial agents was determined by the broth microdilution method. The resistant rates to penicillin G and oxacillin were higher than 90%. There were no isolates resistant to linezolid or vancomycin, and only 6.0% of the strains were resistant to teicoplanin. The positivity rate for mecA genes was 90.2% by polymerase chain reaction (PCR). Ninety MRSH (isolated from inpatients and mecA-gene-positive) were genotyped by pulsed-field gel electrophoresis (PFGE) after SmaI digestion. Twenty-five different PFGE patterns (A approximately Y) were found and a major clone (type A; n = 36) with five subtypes was identified. Clone A was detected during a 1-year period. Identical PFGE types were found in different wards and patients. The results of this study suggest the clonal spread of MRSH within our hospital. This emphasizes the need for control and prevention measures.

Genotypic and Phenotypic Assessment of Hyaluronidase among Type Strains of a Select Group of Staphylococcal Species

Hyaluronidases degrade hyaluronic acid, a major polysaccharide of the extracellular matrix of tissues, and are considered important for virulence in a number of Gram-positive and -negative bacteria. The purpose of the present study was to determine the prevalence of hyaluronidase among clinical strains of Staphylococcus aureus and among other Staphylococcus species. Spent media and chromosomal DNA were assessed for hyaluronidase activity and the absence or presence of a hyaluronidase gene (hysA) by Southern analysis, respectively. All S. aureus strains examined exhibited at least one hybridizing band (half of the strains exhibited two or more hybridizing bands) when probed for hysA and all but three of these strains produced hyaluronidase. In contrast, none of the type strains of 19 other species exhibited either hyaluronidase activity or hybridizing bands when probed for hysA. These data support the hypothesis that among members of the Staphylococcus genus only strains of S. aureus possess the enzyme hyaluronidase. This would suggest that hyaluronidase represents yet another potential virulence factor employed by S. aureus to cause disease and may represent a diagnostically important characteristic for distinguishing S. aureus from other members of this genus.

Update on cardiovascular implantable electronic device infections and their management: a scientific statement from the American Heart Association

Despite improvements in cardiovascular implantable electronic device (CIED) design, application of timely infection control practices, and administration of antibiotic prophylaxis at the time of device placement, CIED infections continue to occur and can be life-threatening. This has prompted the study of all aspects of CIED infections. Recognizing the recent advances in our understanding of the epidemiology, risk factors, microbiology, management, and prevention of CIED infections, the American Heart Association commissioned this scientific statement to educate clinicians about CIED infections, provide explicit recommendations for the care of patients with suspected or established CIED infections, and highlight areas of needed research.

Proof of principle for successful characterization of methicillin-resistant coagulase-negative staphylococci isolated from skin by use of Raman spectroscopy and pulsed-field gel electrophoresis

Coagulase-negative staphylococci (CNS) are among the most frequently isolated bacterial species in clinical microbiology, and most CNS-related infections are hospital acquired. Distinguishing between these frequently multiple-antibiotic-resistant isolates is important for both treatment and transmission control. In this study we used isolates of methicillin-resistant coagulase-negative staphylococci (MR-CNS) that were selected from a large surveillance study of the direct spread of MR-CNS. This strain collection was used to evaluate (i) Raman spectroscopy as a typing tool for MR-CNS isolates and (ii) diversity between colonies with identical and different morphologies. Reproducibility was high, with 215 of 216 (99.5%) of the replicate samples for 72 isolates ending up in the same cluster. The concordance with pulsed-field gel electrophoresis (PFGE)-based clusters was 94.4%. We also confirm that the skin of patients can be colonized with multiple MR-CNS types at the same time. Morphological differences between colonies from a single patient sample correlated with differences in Raman and PFGE types. Some morphologically indistinguishable colonies revealed different Raman and PFGE types. This indicates that multiple MR-CNS colonies should be examined to obtain a complete insight into the prevalence of different types and to be able to perform an accurate transmission analysis. Here we show that Raman spectroscopy is a reproducible typing system for MR-CNS isolates. It is a tool for screening variability within a collection of isolates. Because of the high throughput, it enables the analysis of multiple colonies per patient, which will enhance the quality of clinical and epidemiological studies.