Methicillin-sensitive and methicillin-resistant Staphylococcus aureus nasal carriage in a random sample of non-hospitalized adult population in northern Germany

Nasopharyngeal methicillin-resistant Staphylococcus aureus carriage among pilgrims at the Grand Magal de Touba

Overall prevalence of nasopharyngeal methicillin-resistant Staphylococcus aureus (MRSA) carriage in Grand Magal de Touba pilgrims was 5.2% by PCR and 2.6% acquired carriage following participation in the event. Given the potential for globalization of pathogens, surveillance is crucial to implementing timely interventions and protecting public health during the mass gathering.

Prevalence of methicillin sensitive and resistant Staphylococcus aureus carriage among German emergency medical providers

Background

Health care workers (HCW) in Emergency Medical Services (EMS) frequently come into contact with carriers of methicillin-susceptible Staphylococcus aureus (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA) strains and may acquire and transmit them to patients. However, there is little data on MSSA and MRSA colonization of medical personnel in the emergency services. Additionally, few studies have analyzed the association between personal hygiene of staff and colonization. Therefore, we examined the prevalence of MSSA and MRSA in EMS staff of two German regions and evaluated their personal hygiene behavior.

Method

Throat and nasal swabs from 300 EMS workers were analyzed. Both direct and pre-enriched cultures of the swabs were cultivated on culture media to identify MSSA and MRSA. Results were analyzed together with questionnaires about sociodemographic data and a self-assessment of hygiene behavior. Statistical analysis was done using the R statistical software.

Results

Of the total 300 swabs, 55% were from paramedics, 39% were from emergency medical technicians (EMT) and 5% were from emergency physicians. With 1%, the MRSA prevalence was comparable to that of the German population, while the MSSA rate - 43.7% - was higher than expected. Colonization with MSSA was significantly associated with poor hand hygiene and male sex, and was inversely correlated to time on the job in EMS.

Conclusion

The sample size of 300 and a MRSA prevalence of 1% made a meaningful analysis of potential influencing factors on the prevalence of MRSA infeasible. The comparatively high prevalence of MSSA and the association with decreasing frequency of hand antisepsis suggests an influence of personal hygiene on MSSA colonization. HCW in EMS should be encouraged to make use of their personal protective equipment and practice frequent hand hygiene. The implementation of diagnostic tools such as the Hand Hygiene Self-Assessment Framework of the WHO could be utilized to reveal problems in organizations, followed by an individual program to promote hand hygiene.

Nasal Staphylococcus aureus Carriage and Antimicrobial Resistance Profiles Among Community-Dwelling Adults in Jiangsu, China

INTRODUCTION

Persistent nasal carriage has been associated with Staphylococcus aureus infection. Previous S. aureus studies in Asia have primarily focused on clinical patients, providing limited information on persistent nasal carriage among the general adult population.

METHODS

This study examined 143 healthy adults in a community in Jiangsu, China. Nasal swab samples were collected 10 times. The colonization status was identified using SPA typing. We also determined antimicrobial susceptibility, genotype, and genomic characteristics of S. aureus.

RESULTS

The prevalence of S. aureus nasal carriage among the community individuals was on average 16.78%. The carriage rates of methicillin-resistant S. aureus and multidrug-resistant S. aureus were 6.29% and 7.69%, respectively. We identified 8.39% persistent carriers, 39.16% intermittent carriers, and 52.45% noncarriers. Furthermore, family members displayed concordance in terms of genotype and genomic characteristics.

CONCLUSION

Persistent nasal sampling captured intermittent carriers that were missed during short-term sampling, thus highlighting the necessity for regular community testing. SPA typing can serve as a rapid method for determining S. aureus colonization. The potential for intrafamilial transmission of S. aureus is evident, with persistent carriers being the most probable source of infection.

A look at staphylococci from the one health perspective

Staphylococcus aureus and other staphylococcal species are resident and transient multihost colonizers as well as conditional pathogens. Especially S. aureus represents an excellent model bacterium for the "One Health" concept because of its dynamics at the human-animal interface and versatility with respect to host adaptation. The development of antimicrobial resistance plays another integral part. This overview will focus on studies at the human-animal interface with respect to livestock farming and to companion animals, as well as on staphylococci in wildlife. In this context transmissions of staphylococci and of antimicrobial resistance genes between animals and humans are of particular significance.

Staphylococcus aureus Carriage in the Nasotracheal Cavities of White Stork Nestlings (Ciconia ciconia) in Spain: Genetic Diversity, Resistomes and Virulence Factors

The molecular ecology of Staphylococcus aureus in migratory birds (such as white storks) is necessary to understand their relevance in the "One Health" ecosystems. This study determined the nasotracheal carriage rates of S. aureus from white storks in Southern Spain and genetically characterized the within-host diversity. A collection of 67 S. aureus strains, previously obtained from 87 white stork nestlings (52 nasal and 85 tracheal samples) fed by their parents with food foraged in natural and landfill habitats, were tested for their antimicrobial resistance (AMR) phenotypes. Moreover, the AMR genotypes, immune evasion cluster (IEC), virulence genes and the detection of CC398 lineage were studied by PCR. The spa types and multilocus-sequencing-typing (MLST) were also determined by PCR and sequencing. Staphylococcus aureus carriage was found in 31% of storks (36.5%/11.9% in nasal/tracheal samples). All isolates were methicillin-susceptible (MSSA) and 8.8% of them were also susceptible to all tested antibiotics. The AMR phenotype/percentage/genes detected were as follows: penicillin/79.1%/blaZ; erythromycin-clindamycin-inducible/19.1%/ermA, ermT; tetracycline/11.9%/tetK; clindamycin/4.5%/lnuA and ciprofloxacin/4.5%. Twenty-one different spa types, including 2 new ones (t7778-ST15-CC15 and t18009-ST26-CC25), were detected and ascribed to 11 clonal complexes (CCs). MSSA-CC398 (8.2%), MSSA-CC15 (7.1%) and MSSA-ST291 (5.9%) were the most prevalent lineages in storks. Moreover, tst-positive (MSSA-CC22-t223 and MSSA-CC30-t1654), eta-positive (MSSA-CC9-t209) and etb-positive strains (MSSA-CC45-t015) were detected in four storks. The 18.5% of storks harboured distinct MSSA strains (with different lineages and/or AMR genes). Nestlings of storks foraging in landfills (10 CCs) had more diverse S. aureus strains than those of parents foraging in natural habitats (3 CCs). Low level of AMR was demonstrated among S. aureus strains. The predominance of MSSA-CC398 (an emergent clade) and toxigenic MSSA strains in stork nestlings highlight the need for continuous surveillance of S. aureus in wild birds.

[Therapy-relevant antibiotic resistances in a One Health context]

One Health refers to a concept that links human, animal, and environmental health. In Germany, there is extensive data on antibiotic resistance (AMR) and multidrug-resistant (micro)organisms (MDRO) in human and veterinary medicine, as well as from studies in various environmental compartments (soil, water, wastewater). All these activities are conducted according to different specifications and standards, which makes it difficult to compare data. A focus on AMR and MDRO of human therapeutic importance is helpful to provide some guidance. Most data are available across sectors on methicillin-resistant Staphylococcus aureus (MRSA) and multiresistant Enterobacterales such as Escherichia coli and Klebsiella pneumoniae. Here, the trends of resistance are heterogeneous. Antibiotic use leads to MRE selection, which is well documented. Success in minimizing antibiotic use has also been demonstrated in recent years in several sectors and could be correlated with success in containing AMR and MDRO (e.g., decrease in MRSA in human medicine). Sector-specific measures to reduce the burden of MDRO and AMR are also necessary, as not all resistance problems are linked to other sectors. Carbapenem resistance is still rare, but most apparent in human pathogens. Colistin resistance occurs in different sectors but shows different mechanisms in each. Resistance to antibiotics of last resort such as linezolid is rare in Germany, but shows a specific One Health correlation. Efforts to harmonize methods, for example in the field of antimicrobial susceptibility testing and genome-based pathogen and AMR surveillance, are an important first step towards a better comparability of the different data collections.

Bacterial Genotype, Carrier Risk Factors, and an Antimicrobial Stewardship Approach Relevant To Methicillin-resistant Staphylococcus Aureus Prevalence in a Population of Macaques Housed in a Research Facility

Methicillin-resistant Staphylococcus aureus (MRSA) remains a significant problem for human and animal health and can negatively affect the health status of macaques and other nonhuman primates (NHP) in research colonies. However, few publications provide guidance on the prevalence, genotype, or risk factors for macaques with MRSA and even fewer on how to effectively respond to MRSA once identified in a population. After having a clinical case of MRSA in a rhesus macaque, we sought to determine the MRSA carrier prevalence, risk factors, and genotypes of MRSA in a population of research NHPs. Over a 6-wk period in 2015, we collected nasal swabs from 298 NHPs. MRSA was isolated from 28% (n = 83). We then reviewed each macaque's medical record for a variety of variables including animal housing room, sex, age, number of antibiotic courses, number of surgical interventions, and SIV status. Analysis of these data suggests that MRSA carriage is associated with the room location, age of the animal, SIV status, and the number of antibiotic courses. We used multilocus sequence typing and spa typing on a subset of MRSA and MSSA isolates to determine whether the MRSA present in NHPs was comparable with common human strains. Two MRSA sequence types were predominant: ST188 and a novel MRSA genotype, neither of which is a common human isolate in the United States. We subsequently implemented antimicrobial stewardship practices (significantly reducing antimicrobial use) and then resampled the colony in 2018 and found that MRSA carriage had fallen to 9% (26/285). These data suggest that, as in humans, macaques may have a high carrier status of MRSA despite low clinically apparent disease. Implementing strategic antimicrobial stewardship practices resulted in a marked reduction in MRSA carriage in the NHP colony, highlighting the importance of limiting antimicrobial use when possible.

The association between antibiotics and community-associated Staphylococcus aureus colonization in the United States population: Analysis of the National Health and Nutrition Examination Survey (NHANES)

Staphylococcus aureus nasal colonization is a seriously opportunistic infection. However, there is a lack of research of relationship between antibiotics and S aureus colonization in the general population. Through a cross-sectional investigation, this study intends to establish the parameters related to S aureus nasal colonization, specifically the function antibiotics play in colonization. The key information from 2001 to 2004 was abstracted from National Health and Nutrition Examination Survey (NHANES), including information on general demographics, health care status, antibiotic prescription, diabetes, alcohol consumption, and tobacco smoke exposure. The participants colonized with methicillin-susceptible S aureus (MSSA), or methicillin-resistant S aureus (MRSA) were defined as the case group, and the control group was subjects without positive S aureus colonization. Univariate and multivariate logistic regression models were used to identify the variables associated with MSSA and MRSA colonization. The records of 18,607 individuals were included, involving 13,205 cases without S aureus colonization, 5195 cases with MSSA, and 207 cases with MRSA. In the multivariate logistic regression analysis, the risk of MSSA colonization was significantly reduced with fluoroquinolone use (75% risk reduction, P = .02), sulfonamide use (98% risk reduction, P < .01), tetracycline use (81% risk reduction, P < .01) and antibiotic combination therapy (risk reduction 76%, P < .01). Female, race and total household size were strongly associated with MSSA carriage. On the other hand, regarding MRSA colonization, fluoroquinolone use, long-term care, and former smoker were positively associated with MRSA colonization, while high income was negatively associated with MRSA colonization. More proper use of broad-spectrum antibiotics contributes to reducing MSSA colonization. Former smokers should also practice better personal hygiene to limit the possibility of MRSA colonization.

Characteristics of Virulence Genes of Clinically Isolated Staphylococci in Jingzhou Area

Purpose

The aim of this study was to further understand the distribution characteristics of staphylococcal virulence genes in the Jingzhou area, in order to provide a basis for clinically effective treatments and prevention and control measures.

Methods

A total of 181 strains of staphylococci were collected from Jingzhou Hospital Affiliated to Yangtze University from April 2013 to April 2021, which were divided into the methicillin-resistant Staphylococcus aureus (MRSA) strains and the methicillin-sensitive Staphylococcus aureus (MSSA) strains and coagulase-negative staphylococci (CoNS) by an antimicrobial susceptibility test and PCR method. The 73 MRSA strains were classified by staphylococcal cassette chromosome mec (SCCmec) and Staphylococcus protein A (Spa). Sea, sec, seh, sek, seb, seq, sep, Tsst-1, clfA, clfB, fnbA, hla, hld, hlg, lukE, bbp, cna, eap, ebpS, sdrC, sdrD, sdrE, and Pvl genes were also detected in all strains. The χ² test was used for statistical analysis for comparison between groups.

Results

The 181 strains of staphylococci were divided into 97 strains of MRSA, 54 strains of MSSA, and 30 strains of CoNS. 73 MRSA strains were derived from clinical specimens such as lower respiratory tract, secretions, sepsis secreted by tissue infection, urine, and hydrothorax. There were 70 strains that can be identified including SCCmec types and 15 Spa types of all strains, while the most popular types were SCCmecIII-t030 and SCCmecIV-t437 from lower respiratory tract specimens. There were four virulence genes that were detected including seb, seq, clfB, and hld in CoNS strains, while the detection rates of these four virulence genes in Staphylococcus aureus were higher than that of CoNS, and the differences were statistically significant, P < 0.05(P=0.004, P=0.001, P=0.001, P=0.001). 23 virulence genes were detected in 151 strains of Staphylococcus aureus, among which the detection rate of the Tsst-1 gene was the lowest and that of the clfB gene was the highest, and the other genes were 4.6%∼98.0%. The detection rates of sea, sek, seb, seq, sep, cna, eap, ebpS, sdrC, and sdrE virulence genes in MRSA were higher than that of MSSA, and the differences were statistically significant, P < 0.05 (P=0.001, P=0.001, , P=0.001, P=0.001, P=0.009, , P=0.019, P=0.001, , P=0.001, P=0.001, , P=0.003).

Conclusion

The mainly prevalent type of MRSA strains in Jingzhou is SCCmecIII-t030 in lower respiratory tract specimens. Virulence genes of Staphylococcus aureus and antibiotic drug resistance rates are also different from other regions. In this experiment, virulence genes were also detected in CoNS, suggesting that more attention should be paid to the prevention and treatment of these strains clinically.

Colonization of Dogs and Their Owners with Staphylococcus aureus and Staphylococcus pseudintermedius in Households, Veterinary Practices, and Healthcare Facilities

There are uncertainties with respect to the transmission of methicillin-susceptible and methicillin-resistant Staphylococcus aureus (MSSA and MRSA) and Staphylococcus pseudintermedius between dogs and humans. In this study, we investigated concomitant nasal colonization of dogs and humans in three cohorts. Cohort I, households owning dogs: In 42 of 84 households, 66 humans (36.9%) and 10 dogs (8.9%) carried S. aureus. MRSA, attributed to sequence type (ST) 22 and ST130, were detected in two (1.1%) of the humans but in none of the dogs. Typing by means of spa-typing and whole-genome sequencing (WGS) indicated eight transmissions of S. aureus between humans and dogs in 8 of 42 (19.0%) households with human S. aureus carriers, whereas in 11 of 38 (29.0%) households with ≥two persons and S. aureus colonization of humans, 15 human-to-human transmissions were observed (p = 0.43). S. pseudintermedius was isolated from 42 dogs (37.5%), but from only one human (0.6%). In this case, WGS-based typing indicated strong relatedness of this isolate with a canine isolate from the same household. Cohort II, dogs and their owners visiting a veterinary practice: Among 17 humans and 17 dogs attending a veterinary practice, MSSA was detected in three humans and two dogs, and S. pseudintermedius in only six dogs. Cohort III, dogs used for animal-assisted interventions in human healthcare facilities and their owners: MSSA was obtained in 1 of 59 dogs (1.7%) and in 17 of 60 (28.3%) of the dog owners, while S. pseudintermedius was isolated from seven (12%) dogs and one (1.7%) human owner. We conclude that the risk of exchanging S. aureus/MRSA between humans and dogs is higher than that for S. pseudintermedius.

Mutations in the gdpP gene are a clinically relevant mechanism for β-lactam resistance in meticillin-resistant Staphylococcus aureus lacking mec determinants

In Staphylococcus aureus, resistance to β-lactamase stable β-lactam antibiotics is mediated by the penicillinbinding protein 2a, encoded by mecA or by its homologues mecB or mecC. However, a substantial number of meticillin-resistant isolates lack known mec genes and, thus, are called meticillin resistant lacking mec (MRLM). This study aims to identify the genetic mechanisms underlying the MRLM phenotype. A total of 141 MRLM isolates and 142 meticillin-susceptible controls were included in this study. Oxacillin and cefoxitin minimum inhibitory concentrations were determined by broth microdilution and the presence of mec genes was excluded by PCR. Comparative genomics and a genome-wide association study (GWAS) approach were applied to identify genetic polymorphisms associated with the MRLM phenotype. The potential impact of such mutations on the expression of PBP4, as well as on cell morphology and biofilm formation, was investigated. GWAS revealed that mutations in gdpP were significantly associated with the MRLM phenotype. GdpP is a phosphodiesterase enzyme involved in the degradation of the second messenger cyclic-di-AMP in S. aureus. A total of 131 MRLM isolates carried truncations, insertions or deletions as well as amino acid substitutions, mainly located in the functional DHH-domain of GdpP. We experimentally verified the contribution of these gdpP mutations to the MRLM phenotype by heterologous complementation experiments. The mutations in gdpP had no effect on transcription levels of pbp4; however, cell sizes of MRLM strains were reduced. The impact on biofilm formation was highly strain dependent. We report mutations in gdpP as a clinically relevant mechanism for β-lactam resistance in MRLM isolates. This observation is of particular clinical relevance, since MRLM are easily misclassified as MSSA (meticillin-susceptible S. aureus), which may lead to unnoticed spread of β-lactam-resistant isolates and subsequent treatment failure.

Ecology and Genetic Lineages of Nasal Staphylococcus aureus and MRSA Carriage in Healthy Persons with or without Animal-Related Occupational Risks of Colonization: A Review of Global Reports

In this conceptual review, we thoroughly searched for appropriate English articles on nasal staphylococci carriage among healthy people with no reported risk of colonization (Group A), food handlers (Group B), veterinarians (Group C), and livestock farmers (Group D) published between 2000 and 2021. Random-effects analyses of proportions were performed to determine the pooled prevalence of S. aureus, MRSA, MRSA-CC398, and MSSA-CC398, as well as the prevalence of PVL-positive S. aureus from all eligible studies. A total of 166 eligible papers were evaluated for Groups A/B/C/D (n = 58/31/26/51). The pooled prevalence of S. aureus and MRSA in healthy humans of Groups A to D were 15.9, 7.8, 34.9, and 27.1%, and 0.8, 0.9, 8.6, and 13.5%, respectively. The pooled prevalence of MRSA-CC398 nasal carriage among healthy humans was as follows: Group A/B (<0.05%), Group C (1.4%), Group D (5.4%); and the following among Group D: pig farmers (8.4%) and dairy farmers (4.7%). The pooled prevalence of CC398 lineage among the MSSA and MRSA isolates from studies of the four groups were Group A (2.9 and 6.9%), B (1.5 and 0.0%), C (47.6% in MRSA), and D (11.5 and 58.8%). Moreover, MSSA-CC398 isolates of Groups A and B were mostly of spa-t571 (animal-independent clade), while those of Groups C and D were spa-t011 and t034. The MRSA-CC398 was predominately of t011 and t034 in all the groups (with few other spa-types, livestock-associated clades). The pooled prevalence of MSSA and MRSA isolates carrying the PVL encoding genes were 11.5 and 9.6% (ranges: 0.0-76.9 and 0.0-28.6%), respectively. Moreover, one PVL-positive MSSA-t011-CC398 isolate was detected in Group A. Contact with livestock and veterinary practice seems to increase the risk of carrying MRSA-CC398, but not in food handlers. Thus, this emphasizes the need for integrated molecular epidemiology of zoonotic staphylococci.

Distribution and Antibiotics Resistance Pattern of Community-Acquired Methicillin-Resistance Staphylococcus aureus in Southwestern Nigeria

BACKGROUND

Methicillin-resistant Staphylococcus aureus is a global public health challenge and there is a continuous increase in community-acquired infections among people in different geographical location. We sought the distribution and antibiotics pattern of community-acquired methicillin-resistant Staphylococcus isolates among apparently healthy residents of Ibadan, Southwestern Nigeria.

METHODS

Seven hundred (700) healthy volunteers residing in Ibadan metropolis, Nigeria, were enrolled in this study. Isolates from the nasal swabs were aseptically collected and characterized using standard and established microbiological methods, which included growth and fermentation on mannitol salt agar, colonial morphology, Gram-staining reaction, Microbact™ 12S identification kit and confirmed with 16SrRNA. After identification of the isolates, antimicrobial susceptibility test was performed on Mueller-Hinton agar by modified Kirby-Bauer disc diffusion method and the presence of mecA and nuc genes were detected via polymerase chain reaction assay.

RESULTS

Prevalence of Staphylococcus aureus nasal carriage and Methicillin-resistant Staphylococcus in this study was 31.9% and 9.43% respectively. The residents of Ibadan North local government area (Fisher's Exact = 1.8962, P = .028) and Egbeda local government area (Fisher's Exact = 2.7222, P = .006) are likely to carry Methicillin-resistant Staphylococcus than any other local government area in Ibadan, Nigeria. The antimicrobial resistance patterns of the isolates revealed high resistance to Oxacillin (96.9%). Most of the isolates were sensitive to vancomycin (92.4%). Polymerase chain reaction analysis showed that mecA gene was present in all 66 (100%) Methicillin-resistant Staphylococcus aureus isolates. Male-gender (ϰ² = 8.849, P = .003), Adults; 40-50 years old (ϰ² = 9.842, P = .002), low educational background (ϰ² = 36.817, P ˂ .001), recent hospital visitation (ϰ² = 8.693, P = .003) are some of the factors that are observed in this study to be associated with Methicillin-resistant Staphylococcus infection.

CONCLUSION

Our findings revealed the relatively high frequency of nasal carriers of Methicillin-resistant Staphylococcus aureus among the apparently healthy residents of the studied area and the advent of multidrug resistance among these isolates. Our study also supports previous findings on male-gender and low educational background as risk factors of S. aureus carriage. The need for rational chemotherapy, routine detection and regular surveillance of Methicillin-resistant Staphylococcus to limit its spread and reduce treatment failures is important.

Staphylococcus aureus nasal colonization among dental health care workers in Northern Germany (StaphDent study)

Methicillin-resistant Staphylococcus aureus (MRSA) can colonize dental patients and students, however, studies on the prevalence of MRSA and methicillin-susceptible S. aureus (MSSA) among dental health care workers (DHCW) including use of personal protective equipment (PPE) are scarce. We conducted an observational study (StaphDent study) to (I) determine the prevalence of MRSA and MSSA colonization in DHCW in the region of Mecklenburg Western-Pomerania, Germany, (II) resolve the S. aureus population structure to gain hints on possible transmission events between co-workers, and (III) clarify use of PPE. Nasal swabs were obtained from dentists (n = 149), dental assistants (n = 297) and other dental practice staff (n = 38). Clonal relatedness of MSSA isolates was investigated using spa typing and, in some cases, whole genome sequencing (WGS). PPE use was assessed by questionnaire. While 22.3% (108/485) of the participants were colonized with MSSA, MRSA was not detected. MSSA prevalence was not associated with size of dental practices, gender, age, or duration of employment. The identified 61 spa types grouped into 17 clonal complexes and four sequence types. Most spa types (n = 47) were identified only once. In ten dental practices one spa type occurred twice. WGS data analysis confirmed a close clonal relationship for 4/10 isolate pairs. PPE was regularly used by most dentists and assistants. To conclude, the failure to recover MRSA from DHCW reflects the low MRSA prevalence in this region. Widespread PPE use suggests adherence to routine hygiene protocols. Compared to other regional HCW MRSA rates the consequent usage of PPE seems to be protective.

Als3-Th-cell-epitopes plus the novel combined adjuvants of CpG, MDP, and FIA synergistically enhanced the immune response of recombinant TRAP derived from Staphylococcus aureus in mice

INTRODUCTION

Staphylococcus aureus (S. aureus) is a gram-positive opportunistic pathogen, there are currently no high effective vaccine against S. aureus in humans and animals, the development of an efficient vaccine remains an important challenge to prevent S. aureus infection. Here, we prepared Als3-Th-cell-epitope-Target of RNAIII Activating Protein (TRAP) (ATT) proteins plus the novel combined adjuvants to develop a promising vaccine candidate against S. aureus.

METHODS

The recombinant pET-28a (+)-att plasmids were constructed, and the ATT proteins were expressed and obtained, then, ATT plus Freund's adjuvant or the novel combined adjuvants of cytosine-phosphate-guanosine oligodeoxynucleotides (CpG), muramyl dipeptides (MDP), and FIA were immunized in mice. After booster immunization, the levels of interferon-γ (IFN-γ), interleukin-4 (IL-4), IL-10 and IL-17A cytokine were evaluated, the humoral immune responses against TRAP were detected in mice, and the survival rate of mice was confirmed by challenge assay.

RESULTS

The mice immunized with ATT plus Freund's adjuvant exhibited significantly higher level of IFN-γ, IL-4, IL-10, and IL-17A, and displayed the stronger humoral immune response against TRAP than control groups, importantly, the survival rate of these mice was significantly higher than control groups. In addition, compared with the control groups, ATT + CpG + MDP + FIA group was elicited significantly higher level of IFN-γ, IL-4, IL-10, and IL-17A and was triggered the stronger humoral immune responses against TRAP, moreover, generated the higher survival rate of mice.

CONCLUSION

Als3 epitopes significantly enhanced TRAP immunogenicity. ATT plus the novel combined adjuvants of CpG, MDP, and FIA induced the strong immune response and protection against S. aureus, revealing the combination of CpG, MDP, and FIA adjuvant acts the synergistic effect.

Prevalence of methicillin-sensitive, methicillin-resistant Staphylococcus aureus, and extended-spectrum beta-lactamase-producing Escherichia coli in newborns: a cross-sectional study

BACKGROUND

The prevalence of antimicrobial-resistant bacteria and methicillin-sensitive Staphylococcus aureus (MSSA) in healthy newborns and the role of maternal transmission are scarcely discussed.

OBJECTIVES

The objective of this study was to evaluate the prevalence of MSSA, MRSA, and ESBL among healthy newborns. Additionally, mother-to-newborn transmission rates were investigated as well as antibiotic susceptibility of MSSA, MRSA, and ESBL isolates.

METHODS

Swabs of 658 newborns and their mothers were collected to investigate the presence of MSSA, MRSA, and ESBL. Swabs were taken from the nose and umbilicus immediately after birth. Additional swabs were taken from the nose, perianal area, and umbilicus 3 days after birth. Samples were screened and further characterized using culture and molecular methods.

RESULTS

Prevalence of MSSA, MRSA, and ESBL colonization was 10.9, 0.5, and 2.6%, respectively. There was no association between the colonization status of the newborn and infections at any time point. Mother-to-newborn transmission rates (confirmed by PFGE) were 53.6% for MSSA/MRSA and 100% for ESBL. Maternal carriage of MSSA, MRSA, or ESBL was a risk factor for colonization of the newborn. Some isolates were resistant to the antibiotics recommended for therapy, including clindamycin and daptomycin for MSSA/MRSA isolates and ertapenem, fosfomycin, and tigecyclin for ESBL isolates.

CONCLUSION

No association between infections and the newborns' colonization status could be detected. Maternal colonization played an important role in newborn colonization, but not every case of colonization could be explained by mother-to-newborn transmission. General screening of pregnant women and healthy newborns in the absence of other risk factors is not necessary. To prevent the possibility of transmission in the healthcare setting, professionals, pregnant women, parents, hospital visitors, and obstetricians should receive regular training on appropriate hygiene measures. With regard to the emergence of resistance to recommended antibiotics, an antibiogram should be conducted before treating MSSA/MRSA/ESBL infections to ensure the efficacy of the antibiotics.

Development and external validation of a clinical prediction model for MRSA carriage at hospital admission in Southeast Lower Saxony, Germany

In countries with low endemic Methicillin-resistant Staphylococcus aureus (MRSA) prevalence, identification of risk groups at hospital admission is considered more cost-effective than universal MRSA screening. Predictive statistical models support the selection of suitable stratification factors for effective screening programs. Currently, there are no universal guidelines in Germany for MRSA screening. Instead, a list of criteria is available from the Commission for Hospital Hygiene and Infection Prevention (KRINKO) based on which local strategies should be adopted. We developed and externally validated a model for individual prediction of MRSA carriage at hospital admission in the region of Southeast Lower Saxony based on two prospective studies with universal screening in Braunschweig (n = 2065) and Wolfsburg (n = 461). Logistic regression was used for model development. The final model (simplified to an unweighted score) included history of MRSA carriage, care dependency and cancer treatment. In the external validation dataset, the score showed a sensitivity of 78.4% (95% CI: 64.7-88.7%), and a specificity of 70.3% (95% CI: 65.0-75.2%). Of all admitted patients, 25.4% had to be screened if the score was applied. A model based on KRINKO criteria showed similar sensitivity but lower specificity, leading to a considerably higher proportion of patients to be screened (49.5%).

Molecular Characteristics, Antimicrobial Resistance and Virulence Gene Profiles of Staphylococcus aureus Isolates from Wuhan, Central China

PURPOSE

This study aimed to investigate the molecular characteristics, antimicrobial resistance and virulence genes profiles of S. aureus isolates from Wuhan, central China.

MATERIALS AND METHODS

A total of 302 non-duplicate S. aureus isolates were collected successively during January-December 2018 and subjected to multi-locus sequence typing (MLST), staphylococcal protein A (spa) typing and Panton-Valentine leucocidin (PVL) and staphylococcal enterotoxin A, B, C, D, E, G, H and I (sea, seb, sec, sed, see, seg, seh and sei) detection. All methicillin-resistant S. aureus (MRSA) isolates were additionally subjected to staphylococcal chromosomal cassette mec(SCCmec) typing.

RESULTS

Of the 302 S. aureus isolates, 131 were categorised as MRSA, yielding a rate 1.4 times the average rate in China during 2018 (43.4% vs 30.9%). Thirty-one sequence types (STs) and 82 spa types were identified. The most prevalent clones were ST5-t2460 (10.9%), ST239-t030 (9.3%), ST188-t189 (7.9%) and ST59-t437 (6.3%). Notably, the continued prevalence of ST239-t030 in Wuhan differs from other areas in China. SCCmec types and subtypes I, II, III, IVa and V were present in 0.8%, 36.6%, 26.0%, 20.6% and 8.4% of MRSA isolates. A comprehensive analysis identified ST5-t2460-SCCmec II (25.2%,), ST239-t030-SCCmec III (19.8%) and ST59-t437-SCCmec IVa (7.6%) as the major clones among MRSA isolates. The genes pvl, sea, seb, sec, sed, see, seg, seh and sei were detected at respective frequencies of 11.9%, 42.1%, 49.7%, 45.0%, 20.9%, 33.8%, 60.5%, 25.8% and 66.9%.

CONCLUSION

ST239-t030 remains one of the most prevalent clones in S. aureus isolates from Wuhan, leading us to conclude that S. aureus isolates from Wuhan possess unique molecular characteristics. The S. aureus isolates also exhibit unique antimicrobial resistance profiles and harbour relatively high numbers of enterotoxin virulence genes, compared with other reports from China.

The novel combinations of CTB, CpG, and aluminum hydroxide significantly enhanced the immunogenicity of clumping factor A 221-550 of Staphylococcus aureus

Here, we prepared the novel combined adjuvants, CTB as intra-molecular adjuvant, CpG and aluminum hydroxide (Alum) to strengthen the immunogenicity of clumping factor A_221-550 of Staphylococcus aureus (S. aureus). The protein-immunoactive results showed CTB-ClfA_221-550 elicited the strong immune responses to serum from mice immunized with CTB and ClfA_221-550, respectively. The mice immunized with CTB-ClfA_221-550 plus CpG and Alum adjuvant exhibited significantly stronger CD4⁺ T cell responses for IFN-γ, IL-2, IL-4, and IL-17 and displayed the higher proliferation response of splenic lymphocytes than the control groups, in addition, these mice generated the strongest humoral immune response against ClfA_221-550 among all groups. Our results also showed CTB-ClfA_221-550 plus CpG and Alum adjuvant obviously increased the survival percentage of the mice challenged by S. aureus. These data suggested that the novel combined adjuvants, CTB, CpG, and Alum, significantly enhance the immune responses triggered with ClfA_221-550, and could provide a new approach against infection of S. aureus.

ABBREVIATIONS

CTB: Cholera Toxin B; CpG: Cytosine preceding Guanosine; ODN: Oligodeoxynucleotides; Alum: Aluminum hydroxide; TRAP: Target of RNAIII-activating Protein; TLR9: Toll-like Receptor 9; TMB: 3, 3', 5, 5'-tetramethylbenzidine; mAbs: Monoclonal Antibodies; OD: Optical Densities; S. aureus: Staphylococcus aureus; ClfA: Clumping factor A; FnBPA: Fibronection-binding protein A; IsdB: Iron-regulated surface determinant B; SasA: Staphylococcus aureus Surface Protein A; GapC: Glycer-aldehyde-3-phosphate dehydrogenase-C.

Epidemiological characteristics of methicillin-resistant Staphylococcus aureus isolates from bloodstream cultures at University Hospital in the Czech Republic

The aim of this study was to trace the dynamic changes of methicillin-resistant Staphylococcus aureus (MRSA) lineages in the local hospital in both the national and international context. We describe genotypic and phenotypic characterization of 62 non-duplicate MRSA isolates collected during 2010-2016 at University Hospital in Hradec Kralove, Czech Republic. The isolates were characterized by multilocus sequence typing (MLST), spa typing, and staphylococcal cassette chromosome mec typing (SCCmec typing). Eight different genotypes were described; ST225-t003-II (32/62, 52%), ST5-t002-II (13/62, 22%), and ST225-t014-II (12/62, 21%) were constantly detected over the 7-year follow-up period. The genotypes ST225-t151-II, ST225-t1282-II, ST225-t1623-II, ST78-t2832-II, and ST225-t8799-II occurred only once in the period reported. The majority of the strains, represented by ST225, belonged to clonal complex 5 (CC5).

Prevalence of and risk factors for methicillin-resistant Staphylococcus aureus nasal carriage in the West of Iran: a population-based cross-sectional study

Background

Several reports designate the recent increase in community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) nasal carriage. Because of the scanty information regarding the nasal carriage sate of MRSA in the west of Iran, the purpose of the present study was to determine the frequency of CA-MRSA in Sanandaj city.

Methods

Swabs collected from anterior nares of 600 volunteers were analyzed for the presence of S. aureus. The isolates were further investigated for methicillin resistance by using the cefoxitin disk diffusion test, followed by PCR-amplification of the mecA gene. SCCmec types and the presence of the Panton-Valentine Leukocidin (pvl) encoding genes were determined through PCR. Finally, the antimicrobial susceptibility of the isolates was determined by the agar diffusion method.

Results

Nasal screening identified 181 S. aureus, of which 55 isolates were MRSA. SCCmec types IV and V were detected in MRSA at frequencies of 80 and 20%, respectively. The overall frequency of pvl genes among the MRSA isolates was 14.54%. MRSA isolates were highly susceptible (98.18%) to mupirocin, gentamicin, and fusidic acid.

Conclusions

The high prevalence of CA-MRSA carriage in the population could pose a serious public health concern for the region. Additionally, advent of drug-resistant pvl-positive strains demands continuous surveillance on the colonization state of CA-MRSA in order to prevent dissemination of the bacterium in the community.

Nasal Colonization of Humans with Occupational Exposure to Raw Meat and to Raw Meat Products with Methicillin-Susceptible and Methicillin-Resistant Staphylococcus aureus

Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) is widely disseminated as a nasal colonizer of conventionally raised livestock and of humans subjected to occupational exposure. Reports on contamination of raw meat raise the question as to whether occupationally exposed food handlers are at particular risk of nasal colonization by LA-MRSA. Here, we report the results from a cross-sectional study on nasal S. aureus/MRSA colonization of butchers, meat sellers, and cooks in Germany. We sampled 286 butchers and meat sellers in 26 butcheries and 319 cooks handling meat in 16 professional canteen kitchens. Swabs were processed on both blood agar plates and MRSA-selective plates. MRSA were confirmed by PCR for mec genes and by broth microdilution. All isolates were subjected to molecular typing. PCR for markers useful to differentiate human-adapted and animal-adapted subpopulations was performed due to the presence of clonal complexes known to occur in both livestock and humans (CC5, CC7, CC8, CC9, and CC398). Only two participants (0.33%) were colonized by MRSA (Hospital-associated MRSA ST22). Nasal colonization by methicillin-susceptible S. aureus (MSSA) was detected in 16.6% of cooks and in 26.2% of butchers and meat sellers. Among 16 of the isolates attributed to CC7, three were negative for the immune evasion gene cluster, suggesting an animal origin. Isolates attributed to CC5, CC8, and CC398 were negative for markers typical of animal-adapted subpopulations. The occupational handling of raw meat and raw meat products was not associated with nasal colonization by LA-MRSA.

Determinants of methicillin-resistant Staphylococcus aureus (MRSA) prevalence in the Asia-Pacific region: A systematic review and meta-analysis

OBJECTIVES

Published literature on methicillin-resistant Staphylococcus aureus (MRSA) in the Asia-Pacific region was reviewed to document the prevalence of MRSA in the region and to examine the impact of variability in study design on the reported MRSA prevalence data.

METHODS

This review included studies reporting MRSA prevalence between 2000 and 2016. Studies were excluded if they did not contain complete information on antimicrobial susceptibility testing (AST) methods. Primary outcomes were the proportion of MRSA among S. aureus isolates (resistance proportion) or among individual samples (prevalence).

RESULTS

A total of 229 studies in 19 countries/territories were included in the study. There was substantial heterogeneity in both outcomes (resistance proportion, I²=99.59%; prevalence, I²=99.83%), precluding pooled averages, and meta-regression analyses revealed that these variations were explained by country income status and participant characteristics but not by methodological differences in AST. Also, no significant secular changes in MRSA prevalence or resistance proportions in Asia-Pacific were found.

CONCLUSION

The resistance proportions and prevalence of MRSA infections in Asia-Pacific are comparable with those reported in other regions with no significant secular changes in the past decade. Country income status and characteristics of the sample population explained more variation in the reported resistance proportions and prevalence of MRSA than methodological differences in AST across locations in the region.

Impact of MSSA screening on rates of surgical site infection following lumbar spine surgery

PURPOSE

Methicillin-sensitive Staphylococcus aureus (MSSA) carriage may confer a significant risk of surgical site infection (SSI) and is common amongst the UK population. Screening for MSSA is not routinely offered to patients in the UK. Primary aim was to review the impact of introducing a MSSA screening programme, in addition to established Methicillin-resistant Staphylococcus aureus (MRSA) screening, on the incidence of SSIs following lumbar spine surgery.

METHODS

A consecutive group of 1307 patients during 12 months before (phase 1: n = 716) and after (phase 2: n = 591) introduction of the MSSA screening programme were compared. Analysis was restricted to those with inpatient stay greater than 4 days, readmission within 6 weeks and a rising CRP 7 or more days following the procedure. Diagnosis of SSI was based around the CDC guidelines for wound surveillance. Patients were excluded where the primary surgery was to treat infection, or the procedure was percutaneous. Chi-squared test was used to compare the two groups.

RESULTS

Seven hundred and sixteen patients were in phase 1. Rate of infection was 2.65%. Rate of MRSA colonisation was 0%. Five hundred and ninety-one patients were in phase 2. Rate of infection was 1.02%. Rate of MRSA colonisation was 0%, and rate of MSSA colonisation was 26%. Reduction in incidence of SSIs was 62% (p = 0.0409).

CONCLUSION

MSSA colonisation is common, although wound infection following lumbar spinal surgery remains a rare event. A screening programme for MSSA can significantly reduce incidence of SSIs in this patient group. These findings may be applicable to wider elective orthopaedic practice. These slides can be retrieved under Electronic Supplementary Material.

Control of healthcare- and community-associated MRSA: recent progress and persisting challenges

BACKGROUND

Healthcare adapted meticillin-resistant Staphylococcus aureus (MRSA) has spread to hospitals around the world over 50 years. More recently, other strains of MRSA have emerged with the ability to spread in the community and infect otherwise healthy individuals. Morbidity and mortality associated with MRSA remains high and its control in both the healthcare and community setting has proven challenging.

SOURCES OF DATA

Pubmed (Medline).

AREAS OF AGREEMENT

The use of targeted screening and decolonization, hand hygiene and antimicrobial stewardship is supported by the most robust studies, though many studies have implemented bundles for effective healthcare-associated (HA)-MRSA control.

AREAS OF CONTENTION

Universal screening, universal decolonization and contact precautions for HA-MRSA control are supported by less evidence. Some interventions may not be cost-effective. Contact precautions may be associated with potential for patient harm. Evidence for effective control community acquired (CA)-MRSA is largely lacking.

GROWING POINTS

Programmes that focus on implementing bundles of interventions aimed at targeting HA-MRSA are more likely to be effective, with an emphasis on hand hygiene as a key component. Control of CA-MRSA is likely to be more difficult to achieve and relies on prevalence, risk factors and community healthcare interactions on a broader scale.

AREAS TIMELY FOR DEVELOPING RESEARCH

Further research in the area of CA-MRSA in particular is required. Antimicrobial stewardship for both CA and HA-MRSA is promising, as is the role of whole genome sequencing in characterizing transmission. However, further work is required to assess their long-term roles in controlling MRSA. With many institutions applying widespread use of chlorhexidine washes, monitoring for chlorhexidine resistance is paramount to sustaining efforts at controlling MRSA.

Identification of a novel linear B-cell epitope as a vaccine candidate in the N2N3 subdomain of Staphylococcus aureus fibronectin-binding protein A

PURPOSE

To explore an epitope-based vaccine against Staphylococcus aureus, we screened the epitopes in the N2N3 subdomain of fibronectin-binding protein A (FnBPA) as a surface component of S. aureus.

METHODOLOGY

We expressed N2N3 proteins and prepared monoclonal antibodies (mAbs) against N2N3 by the hybridoma technique, before screening the B-cell epitopes in N2N3 using a phage-displayed random 12-mer peptide library with these mAbs against N2N3. Finally, we analysed the characters of the screened epitopes using immunofluorescence and an S. aureus infection assay.

RESULTS

In this paper, we identified a linear B-cell epitope in N2N3 through screening a phage-displayed peptide library with a 3C3 mAb against the N2N3. The 3C3 mAb recognized the 159IETFNKANNRFSH171 sequence of the N2N3 subdomain. Subsequently, site-directed mutagenic analysis demonstrated that residues F162, K164, N167, R168 and F169 formed the core of 159IETFNKANNRFSH171, and this core motif was the minimal determinant of the B-cell epitope recognized by the 3C3 mAb. The epitope 159IETFNKANNRFSH171 showed high homology among different S. aureus strains. Moreover, this epitope was exposed on the surface of the S. aureus by using an enzyme-linked immunosorbent assay (ELISA) assay and an indirect immunofluorescence assay. As expected, the epitope peptide evoked a protective immune response against S. aureus infection in immunized mice.

CONCLUSION

We identified a novel linear B-cell epitope, 159IETFNKANNRFSH171, in the N2N3 subdomain of S. aureus fibronectin-binding protein A that is recognized by 3C3 mAb, which will contribute to the further study of an epitope-based vaccine candidate against S. aureus.

The double adjuvants LTB and CpG significantly enhanced the immuno-protective effects of recombinant GIT derived from Staphylococcus aureus and Streptococcus in mice

PURPOSE

In this study, we prepared GapC1-150-IsdB126-361-TRAP (GIT) proteins plus heat-labile enterotoxin B (LTB) as an intra-molecular adjuvant, together with CpG to further enhance its immunogenicity.

METHODOLOGY

Initially, the target genes were acquired and inserted into pET-32a (+) vectors to express LTB-GIT protein. LTB-GIT expression was confirmed by Western blotting and its immunocompetence was estimated through ELISA. Further, we immunized BALB/c mice with the LTB-GIT plus CpG adjuvant. After the second immunization, the antigen-specific CD4⁺ cell responses for IFN-γ, IL-2, IL-4 and IL-10 were monitored by intracellular cytokine staining (ICS) assay. After the third immunization, the level of IgG antibodies in the serum from immunized groups was assessed by ELISA, and the protective immune response was appraised by Staphylococcus aureus and Streptococcus dysgalactiae challenge.

RESULTS

The ELISA results showed that the OD450nm value of the LTB-GIT group was significantly higher than that of the BSA group. The group immunized with LTB-GIT plus CpG exhibited significantly stronger CD4⁺ T cell responses for IFN-γ, IL-2, IL-4 and IL-10 compared to the group immunized with LTB-GIT, GIT alone orLTB-GIT plus CpG. In addition, the group immunized with LTB-GIT plus CpG generated the highest level of IgG antibodies against GIT among all of the groups, and our results also showed that LTB-GIT plus CpG markedly improved the survival percentage of mice compared to other groups.

CONCLUSION

We confirmed that the novel double adjuvants, LTB and CpG, are able to significantly improve GIT-induced immune responses. This formula could be a promising strategy for enhancing the immune efficacy of multi-subunit vaccines against Staphylococcus aureus and streptococcal infection.

Staphylococcus aureus and Methicillin-Resistant Staphylococcus aureus in Workers in the Food Industry

Staphylococcus aureus is part of the common flora on the skin and mucous membranes of mammals and approximately 20–30% of humans are persistently colonized, mainly by mostly susceptible human-adapted isolates. In contrast, colonization with methicillin-resistant S. aureus is rare (approximately 1%), predominantly transient and associated with prior contact to the health care system. Additionally, in recent years livestock-associated S. aureus clones contributed to colonization in humans, especially in those working in close contact to farm animals. A considerable percentage of colonizing S. aureus isolates is equipped with enterotoxin genes. Humans carrying enterotoxigenic isolates represent a contamination source when handling food, thus generating a continuous risk of S. aureus food intoxication. Molecular characterization of isolates colonizing humans and obtained from food, respectively, enables the tracing of food-related outbreaks back to the source of food intoxication. We will summarize current knowledge about the S. aureus population colonizing humans, including those in close contact to animals and food, respectively. Additionally, we will review data on the molecular characterization of S. aureus isolates related to staphylococcal foodborne disease and the elucidation of staphylococcal foodborne outbreaks. Staphylococcal food poisoning is a common foodborne disease, mediated by the ingestion of enterotoxins produced by enterotoxigenic strains of S. aureus. For several outbreaks of foodborne S. aureus disease, colonized personnel could be identified as the source of food contamination. However, because of the widespread occurrence of enterotoxigenic strains as human colonizers and the often transient nature of colonization, the source of contamination cannot always be identified unambiguously. Therefore, compliance with hygiene measures is the most important requirement to prevent food contamination by both human colonization and environmental S. aureus reservoirs.

Predictors of colonization with Staphylococcus species among patients scheduled for cardiac and orthopedic interventions at tertiary care hospitals in north-eastern Germany-a prevalence screening study

As methicillin-resistant Staphylococcus aureus (MRSA) colonization and infection in humans are a global challenge. In Mecklenburg and Western Pomerania (Germany) 1,517 patients who underwent surgical interventions were systematically screened for MRSA and MSSA colonization on the day of hospital admission and discharge. Demographic data, risk factors and colonization status of the (i) nose, (ii) throat, (iii) groin, and (iv) thorax or site of surgical intervention were determined. Of the 1,433 patients who were included for further evaluation, 331 (23.1%) were colonized with MSSA, while only 17 (1.2%) were MRSA carriers on the day of hospital admission. A combination of nose, throat and groin swabs returned a detection rate of 98.3% for MSSA/MRSA. Trauma patients had lower prevalence of MRSA/MSSA (OR 0.524, 95% CI: 0.37-0.75; p < 0.001) than patients with intended orthopedic interventions. Males showed significantly higher nasal S. aureus carrier rates than females (odds ratio (OR) = 1.478; 95% CI: 1.14-1.92; p = 0.003). Nasal S. aureus colonization was less frequent among male smokers as compared to non-smokers (chi² = 16.801; phi = 0.154; p < 0.001). Age, gender and smoking had a significant influence on S. aureus colonization. Combining at least three different swabbing sites should be considered for standard screening procedure to determine S. aureus colonization at patients scheduled for cardiac or orthopedic interventions at tertiary care hospitals.

Global spread of mouse-adapted Staphylococcus aureus lineages CC1, CC15, and CC88 among mouse breeding facilities

We previously reported that laboratory mice from all global vendors are frequently colonized with Staphylococcus aureus (S. aureus). Genotyping of a snap sample of murine S. aureus isolates from Charles River, US, showed that mice were predominantly colonized with methicillin-sensitive CC88 strains. Here, we expanded our view and investigated whether laboratory mice from other global animal facilities are colonized with similar strains or novel S. aureus lineages, and whether the murine S. aureus isolates show features of host adaptation. In total, we genotyped 230 S. aureus isolates from various vendor facilities of laboratory mice around the globe (Charles River facilities in the USA, Canada, France, and Germany; another US facility) and university- or company-associated breeding facilities in Germany, China and New Zealand. Spa typing was performed to analyse the clonal relationship of the isolates. Moreover, multiplex PCRs were performed for human-specific virulence factors, the immune-evasion cluster (IEC) and superantigen genes (SAg). We found a total of 58 different spa types that clustered into 15 clonal complexes (CCs). Three of these S. aureus lineages had spread globally among laboratory mice and accounted for three quarters of the isolates: CC1 (13.5%), CC15 (14.3%), and CC88 (47.0%). Compared to human colonizing isolates of the same lineages, the murine isolates frequently lacked IEC genes and SAg genes on mobile genetic elements, implying long-term adaptation to the murine host. In conclusion, laboratory mice from various vendors are colonized with host-adapted S. aureus-strains of a few lineages, predominantly the CC88 lineage. S. aureus researchers must be cautioned that S. aureus colonization might be a relevant confounder in infection and vaccination studies and are therefore advised to screen their mice before experimentation.

Topical vancomycin to reduce surgical-site infections in neurosurgery: Study protocol for a multi-center, randomized controlled trial

Surgical-site infections (SSIs) account for 20% of all healthcare-associated infections, are the most common nosocomial infection among surgical patients, and are a focus of quality improvement initiatives. Despite implementation of many quality care measures (e.g. prophylactic antibiotics), SSIs remain a significant cause of morbidity, mortality, and economic burden, particularly in the field of neurosurgery. Topical vancomycin is increasingly utilized in instrumented spinal and cardiothoracic procedures, where it has been shown to reduce the risk of SSIs. However, a randomized controlled trial assessing its efficacy in the general neurosurgical population has yet to be done. The principle aim of "Topical Vancomycin for Neurosurgery Wound Prophylaxis" (NCT02284126) is to determine whether prophylactic, topical vancomycin reduces the risk of SSIs in the adult neurosurgical population. This prospective, multicenter, patient-blinded, randomized controlled trial will enroll patients to receive the standard of care plus topical vancomycin, or the standard of care alone. The primary endpoint of this study is a SSI by postoperative day (POD) 30. Patients must be over 18years of age. Patients are excluded for renal insufficiency, vancomycin allergy, and some ineligible procedures. Univariate analysis and logistic regression will determine the effect of topical vancomycin on SSIs at 30days. A randomized controlled trial is needed to determine the efficacy of this treatment. Results of this trial are expected to directly influence the standard of care and prevention of SSIs in neurosurgical patients.

Prevalence and correlates of MRSA and MSSA nasal carriage at a Ugandan regional referral hospital

Background

Despite increasing antimicrobial resistance globally, data are lacking on prevalence and factors associated with Staphylococcus aureus (SA) and MRSA carriage in resource-limited settings.

Objectives

To determine the prevalence of SA and MRSA nasal carriage and factors associated with carriage among Ugandan regional referral hospital patients.

Methods

We enrolled a cross-section of 500 adults, sampling anterior nares for SA and MRSA carriage using Cepheid Xpert SA Nasal Complete.

Results

Mean age was 37 years; 321 (64%) were female and 166 (33%) were HIV infected. Overall, 316 (63%) reported risk factors for invasive SA infection; 368 (74%) reported current antibiotic use. SA was detected in 29% and MRSA in 2.8%. MRSA and MSSA carriers were less likely than SA non-carriers to be female (50% and 56% versus 68%, P  = 0.03) or to have recently used β-lactam antibiotics (43% and 65% versus 73%, P  = 0.01). MRSA carriers were more likely to have open wounds than MSSA carriers and SA non-carriers (71% versus 27% and 40%, P  = 0.001) and contact with pigs (21% versus 2% and 6%, P  = 0.008). MRSA carriage ranged from 0% of HIV clinic participants to 8% of inpatient surgical ward participants ( P  =   0.01). In multivariable logistic regression analysis, male sex was independently associated with SA carriage (OR 1.68, 95% CI 1.12-2.53, P  =   0.01) and recent β-lactam antibiotic use was associated with reduced odds of SA carriage (OR 0.61, 95% CI 0.38-0.97, P  =   0.04).

Conclusions

MRSA nasal carriage prevalence was low and associated with pig contact, open wounds and surgical ward admission, but not with HIV infection.

Wild rodents and shrews are natural hosts of Staphylococcus aureus

Laboratory mice are the most commonly used animal model for Staphylococcus aureus infection studies. We have previously shown that laboratory mice from global vendors are frequently colonized with S. aureus. Laboratory mice originate from wild house mice. Hence, we investigated whether wild rodents, including house mice, as well as shrews are naturally colonized with S. aureus and whether S. aureus adapts to the wild animal host. 295 animals of ten different species were caught in different locations over four years (2012-2015) in Germany, France and the Czech Republic. 45 animals were positive for S. aureus (15.3%). Three animals were co-colonized with two different isolates, resulting in 48 S. aureus isolates in total. Positive animals were found in Germany and the Czech Republic in each studied year. The S. aureus isolates belonged to ten different spa types, which grouped into six lineages (clonal complex (CC) 49, CC88, CC130, CC1956, sequence type (ST) 890, ST3033). CC49 isolates were most abundant (17/48, 35.4%), followed by CC1956 (14/48, 29.2%) and ST890 (9/48, 18.8%). The wild animal isolates lacked certain properties that are common among human isolates, e.g., a phage-encoded immune evasion cluster, superantigen genes on mobile genetic elements and antibiotic resistance genes, which suggests long-term adaptation to the wild animal host. One CC130 isolate contained the mecC gene, implying wild rodents might be both reservoir and vector for methicillin-resistant . In conclusion, we demonstrated that wild rodents and shrews are naturally colonized with S. aureus, and that those S. aureus isolates show signs of host adaptation.

[Development of antimicrobial resistance in Germany : What is the current situation?]

BACKGROUND

The frequency of multidrug-resistant organisms (MDRO) is increasing in Germany and worldwide.

OBJECTIVES

Presentation of MDRO resistance rates and prevalence in Germany MATERIALS AND METHODS: Results from the Antibiotic Resistance Surveillance (ARS) and Hospital Infection Surveillance Systems (Krankenhausinfektions-Surveillance-Systems, KISS) and from recent prevalence surveys are presented.

RESULTS

MRSA-resistance rates and the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) have remained at a stable level over the last few years. In contrast, vancomycin-resistant enterococci (VRE) and multidrug-resistant gramnegative (MRGN) bacteria have increased considerably. VRE prevalence has more than tripled in the past 5 years, and Escherichia coli resistant to third-generation cephalosporins, acylureidopenicillins, and fluoroquinolones increased by 43% in 2015 compared with the previous year.

CONCLUSIONS

New policies to control MDRO should focus on VRE and the heterogeneous group of MRGN bacteria. In the case of the latter, the different bacterial species' characteristics should be taken into consideration.

Staphylococcus aureus nasal carriage in health care workers: First report from a major public hospital in Argentina

Staphylococcus aureus causes numerous mild to severe infections in humans, both in health facilities and in the community. Patients and health care workers (HCWs) may disseminate strains during regular medical examinations or hospitalization. The aim of this study was to determine the nasal carriage rate of methicillin-susceptible and methicillin-resistant S. aureus among health care workers at Hospital Provincial del Centenario, a public general hospital in Rosario, Argentina. A transversal study was conducted on 320 health care workers. Nasal swabs were taken and presumptive S. aureus colonies were isolated. Bacterial identity and methicillin resistance status were confirmed by amplification of the nuc and mec genes. Chi square test and Fisher exact test were used for statistical analysis. Of 320 HCWs, 96 (30%) were nasal carriers of S. aureus, 20 of whom (6.3%) carried methicillin-resistant S. aureus (MRSA) and 76 (23.7%) methicillin-susceptible S. aureus (MSSA). Carriage was within thepublished values for physicians (30%) and higher for technicians (57%). Accompanying resistance (62/96, 64.6%) was detected, including resistance to fluoroquinolones (23/96, 24%), aminoglucosides (13/96, 13.5%) or to macrolides (33/96, 34.4%). All the strains were susceptible to vancomycin whereas only 3.1% (3/96), all of them on MSSA strains, were resistant to mupirocin. This study is the first one of its kind in Argentina and one of the few performed in South America, to highlight the relevance of nasal carriage of MRSA and MSSA in health care personnel and brings to light the need for consensus recommendations for regular S. aureus carriage screening as well as for decolonization strategies.

Community-Associated Staphylococcus aureus from Sub-Saharan Africa and Germany: A Cross-Sectional Geographic Correlation Study

Clonal clusters and gene repertoires of Staphylococcus aureus are essential to understand disease and are well characterized in industrialized countries but poorly analysed in developing regions. The objective of this study was to compare the molecular-epidemiologic profiles of S. aureus isolates from Sub-Saharan Africa and Germany. S. aureus isolates from 600 staphylococcal carriers and 600 patients with community-associated staphylococcal disease were characterized by DNA hybridization, clonal complex (CC) attribution, and principal component (PCA)-based gene repertoire analysis. 73% of all CCs identified representing 77% of the isolates contained in these CCs were predominant in either African or German region. Significant differences between African versus German isolates were found for alleles encoding the accessory gene regulator type, enterotoxins, the Panton-Valentine leukocidin, immune evasion gene cluster, and adhesins. PCA in conjunction with silhouette analysis distinguished nine separable PCA clusters, with five clusters primarily comprising of African and two clusters of German isolates. Significant differences between S. aureus lineages in Africa and Germany may be a clue to explain the apparent difference in disease between tropical/(so-called) developing and temperate/industrialized regions. In low-resource countries further clinical-epidemiologic research is warranted not only for neglected tropical diseases but also for major bacterial infections.

[Multidrug-resistant bacteria in Germany. The impact of sources outside healthcare facilities]

BACKGROUND

Currently, there is an ongoing discussion about the question whether the emergence of multidrug-resistant microorganisms (MDRO) among humans is due to transfer of these bacteria from animals.

OBJECTIVES

This review summarizes data on the occurrence of methicillin-resistant Staphylococcus aureus (MRSA) and extended-spectrum beta-lactamase (ESBL) producing enterobacteria in animals and humans, and describes knowledge about transmission pathways.

MATERIAL AND METHODS

After a scientific literature analysis, relevant articles were identified by screening of titles and abstracts, amended by publications of infection control authorities and the respective reference lists.

RESULTS

MDRO are both transmitted in the nosocomial setting and are increasingly detected as sources of infection outside healthcare facilities.

CONCLUSIONS

Due to new transmission pathways of MDRO an inter-disciplinary approach towards prevention is necessary, involving medical, pharmaceutical and veterinary expertise.

Staphylococcus aureus from the German general population is highly diverse

OBJECTIVES

This prospective cohort study evaluates colonization dynamics and molecular characteristics of methicillin-susceptible and - resistant Staphylococcus aureus (MSSA/MRSA) in a German general population.

METHODS

Nasal swabs of 1878 non-hospitalized adults were screened for S. aureus. Participants were screened thrice in intervals of 6-8 months. Isolates were characterized by spa and agr typing, mecA and mecC possession, respectively, and PCRs targeting virulence factors.

RESULTS

40.9% of all participants carried S. aureus at least once while 0.7% of the participants carried MRSA (mainly spa t011). MSSA isolates (n=1359) were associated with 331 different spa types; t084 (7.7%), t091 (6.1%) and t012 (71, 5.2%) were predominant. Of 206 participants carrying S. aureus at all three sampling time points, 14.1% carried the same spa type continuously; 5.3% carried different spa types with similar repeat patterns, but 80.6% carried S. aureus with unrelated spa types. MSSA isolates frequently harboured genes encoding enterotoxins (sec: 16.6%, seg: 63.1%, sei: 64.5%) and toxic shock syndrome toxin (tst: 17.5%), but rarely Panton-Valentine leukocidin (lukS-PV/lukF-PV: 0.2%).

CONCLUSIONS

MSSA colonizing human nares in the community are clonally highly diverse. Among those constantly carrying S. aureus, clonal lineages changed over time. The proportion of persistent S. aureus carriers was lower than reported elsewhere.

Molecular and Phenotypic Characterization Revealed High Prevalence of Multidrug-Resistant Methicillin-Susceptible Staphylococcus aureus in Chongqing, Southwestern China

Methicillin-susceptible Staphylococcus aureus (MSSA) accounts for ∼40% of staphylococcal infections in China. However, the molecular characterization of MSSA is not well described. In this study, 124 MSSA strains collected in 2013 from a comprehensive teaching hospital in Chongqing, Southwestern China, were subjected to antibiotics susceptibility testing and molecular typing, including multilocus sequence typing, staphylococcal protein A (spa) gene typing, accessory gene regulator (agr) typing, pulsed-field gel electrophoresis (PFGE) typing, Panton-Valentine leukocidin (pvl) gene detection, and antibiotic-resistant gene detection. MSSA strains exhibited high genetic heterogeneity. A total of 10 PFGE groups, 26 sequence types, and 47 spa types were identified. Type I (62.9%) was the most frequent agr type, followed by type II (15.3%), type IV (11.3%), and type III (10.5%). The prevalence of pvl genes was 27.4% (34/124). Notably, 44.4% (55/124) of MSSA strains were multidrug resistance (MDR), and MDR isolates were mostly resistant to penicillin, erythromycin, and clindamycin. The resistance gene blaZ was present in 84.7% of strains, ermC was present in 85.5% of strains, ermA was present in 28.2% of strains, tetK was present in 16.1% of strains, tetM was present in 6.5% of strains, and aacA-aphD was present in 2.6% of strains. These data demonstrated the high prevalence of MDR MSSA in Chongqing, thereby indicating the need to control MSSA infection.

Potential Relationship between Phenotypic and Molecular Characteristics in Revealing Livestock-Associated Staphylococcus aureus in Chinese Humans without Occupational Livestock Contact

While some studies have defined Staphylococcus aureus based on its clonal complex and resistance pattern, few have explored the relations between the genetic lineages and antibiotic resistance patterns and immune evasion cluster (IEC) genes. Our aim was to investigate the potential relationship between phenotypic and molecular characteristics so as to reveal livestock-associated S. aureus in humans. The study participants were interviewed, and they provided two nasal swabs for S. aureus analysis. All S. aureus and methicillin-resistant S. aureus (MRSA) were tested for antibiotic susceptibility, multilocus sequence type and IEC genes. Of the 1162 participants, 9.3% carried S. aureus, including MRSA (1.4%) and multidrug-resistant S. aureus (MDRSA, 2.8%). The predominant multidrug-resistant pattern among MDRSA isolates was non-susceptibility to erythromycin, clindamycin and tetracycline. The most common S. aureus genotypes were ST7, ST6, ST188, and ST59, and the predominant MRSA genotype was ST7. Notably, the livestock-associated S. aureus isolates (IEC-negative CC9, IEC-negative tetracycline-resistant CC398, and IEC-negative tetracycline-resistant CC5) were found in people with no occupational livestock contact. These findings reveal a potential relationship between S. aureus CCs and IEC genes and antibiotic resistance patterns in defining livestock-associated S. aureus in humans and support growing concern about the potential livestock-to-human transmission of livestock-associated S. aureus by non-occupational livestock contact.

Molecular Epidemiology of Staphylococcus aureus in the General Population in Northeast Germany: Results of the Study of Health in Pomerania (SHIP-TREND-0)

Population-based studies on Staphylococcus aureus nasal colonization are scarce. We examined the prevalence, resistance, and molecular diversity of S. aureus in the general population in Northeast Germany. Nasal swabs were obtained from 3,891 adults in the large-scale population-based Study of Health in Pomerania (SHIP-TREND). Isolates were characterized using spa genotyping, as well as antibiotic resistance and virulence gene profiling. We observed an S. aureus prevalence of 27.2%. Nasal S. aureus carriage was associated with male sex and inversely correlated with age. Methicillin-resistant S. aureus (MRSA) accounted for 0.95% of the colonizing S. aureus strains. MRSA carriage was associated with frequent visits to hospitals, nursing homes, or retirement homes within the previous 24 months. All MRSA strains were resistant to multiple antibiotics. Most MRSA isolates belonged to the pandemic European hospital-acquired MRSA sequence type 22 (HA-MRSA-ST22) lineage. We also detected one livestock-associated MRSA ST398 (LA-MRSA-ST398) isolate, as well as six livestock-associated methicillin-susceptible S. aureus (LA-MSSA) isolates (clonal complex 1 [CC1], CC97, and CC398). spa typing revealed a diverse but also highly clonal S. aureus population structure. We identified a total of 357 spa types, which were grouped into 30 CCs or sequence types. The major seven CCs (CC30, CC45, CC15, CC8, CC7, CC22, and CC25) included 75% of all isolates. Virulence gene patterns were strongly linked to the clonal background. In conclusion, MSSA and MRSA prevalences and the molecular diversity of S. aureus in Northeast Germany are consistent with those of other European countries. The detection of HA-MRSA and LA-MRSA within the general population indicates possible transmission from hospitals and livestock, respectively, and should be closely monitored.

Methicillin-Resistant Staphylococcus aureus in Saarland, Germany: The Long-Term Care Facility Study

Background

Multiresistant organisms pose a threat for patients and care recipients. Control interventions need to be tailored to region, the type of institution considered, and risk factors. The German state of Saarland is ideally suited to study colonisation epidemiology throughout its various health and care institutions. After conclusion of a large admission prevalence study in acute care hospitals, we now performed a methicillin-resistant Staphylococcus aureus (MRSA) point prevalence study in Saarland long term care facilities (LTCF), allowing for a direct comparison with respect of MRSA prevalence and associated risk factors between these two institutional types located within a confined region.

Methodology and Principal Findings

Of all LTCF of the region, 65/136 participated in the study performed between 09/2013 and 07/2014. Overall, complete microbiological specimen and questionnaires of 2,858 of 4,275 (66.8%) LTCF residents were obtained. 136/2,858 (4.8%) screened residents revealed MRSA carrier status. Multivariate risk factor analysis yielded ulcer/deep soft tissue infection, urinary tract catheter, and MRSA history with multiple MRSA decolonisation cycles to be independently associated with MRSA carrier status.

Conclusion

As already known from previous studies, colonisation with MRSA is common in LTCF residents even in an area with relatively low MRSA prevalence. This found prevalence can now be related to the acute care admission prevalence (2.2%) as well as to the admission prevalence in acute care geriatric departments (7.6%). The common clonal attribution (spa type) of MRSA isolates prevalent in the LTCF population as well as in the acute care admission population points towards a close relationship between both types of institutions. However, the ostensible absence of risk factors such as “previous hospitalisation” in conjunction with newly identified factors such as “multiple decolonisation cycles” refers to MRSA colonisation risks independent of contact with acute care facilities. Overall, this large LTCF point prevalence study allows data-based, region-tailored decisions on MRSA screening policies and provides a basis for additional preventative measures.

Occurrence of cfr-mediated multiresistance in staphylococci from veal calves and pigs, from humans at the corresponding farms, and from veterinarians and their family members

This study reports on the emergence of linezolid-resistant coagulase-negative staphylococci (CoNS) containing the multiresistance gene cfr in veal calves and pigs, as well as in humans exposed to these animals. CoNS (Staphylococcus auricularis, Staphylococcus cohnii, Staphylococcus lentus, Staphylococcus kloosii, Staphylococcus sciuri, Staphylococcus simulans), but not Staphylococcus aureus, carrying the gene cfr were detected in samples of 12 out of 52 calves at three farms which had a history of florfenicol use. Nasal swabs from 10 humans living on these farms were negative for cfr-carrying staphylococci. Nasal swabs taken from 142 calves at 16 farms in the same area that did not use florfenicol were also negative for cfr-carrying staphylococci. 14 cfr-carrying CoNS (S. kloosii, S. saprophyticus, S. simulans) were detected in three of eight conventional pig farms investigated. One of 12 humans living on these farms harboured a cfr-carrying S. cohnii. Among the nasal swabs taken from 169 veterinarians from all over Germany, four (2.3%) were positive for cfr-carrying CoNS (three S. epidermidis, one S. saprophyticus), and three (1.1%) of 263 contact persons of this group also harboured cfr-carrying CoNS (one S. epidermidis, two S. saprophyticus). In vitro conjugation of cfr by filter mating to S. aureus 8325-4 was possible for 10 of 34CoNS and the cfr gene was associated with plasmids of 38-40kb. Moreover, a total of 363 humans of a German municipal community were investigated for nasal carriage of cfr-carrying staphylococci to get an idea whether such isolates are disseminated as nasal colonizers in non-hospitalized humans in the community, were all negative.

Prevalence of MRSA Nasal Carriage in Patients Admitted to a Tertiary Care Hospital in Southern India

INTRODUCTION

Infections with MRSA, both community and hospital acquired, are well established and the source of infection is often a carrier. There are very few studies showing the magnitude of MRSA nasal colonization among healthy persons from the community. This study was conducted to detect the prevalence of MRSA nasal carriage in patients who did not have any known risk factors associated with HA- MRSA colonization, admitted to a tertiary care centre in Kerala.

MATERIALS AND METHODS

Nasal swabs were collected from patients within 24 hours of admission. Specimen were inoculated on chromogenic agar (HiCrome MeReSa agar-HiMedia) for MRSA screening. Isolates were then subjected to antibiotic sensitivity tests, SCCmec typing and PVL gene detection.

RESULTS

Out of 683 patients, 16 carried MRSA in their nares (2.3%). Of the 16 strains 13 (81.25 %) strain were SCCmec type III and one belonged to SCCmec type IV (6.25 %). Two strains failed to amplify SCCmec genes. Three strains carried genes for PVL toxin (18.75%).

CONCLUSION

With a better understanding of the complex epidemiology of MRSA it is increasingly apparent that demarcations between the HA and CA phenotypes are not as clear cut as previously thought. In this study of nasal carriage of MRSA in the community we have demonstrated prevalence consistent with published data. Most isolates however were shown to belong to the type conventionally assigned to HA-MRSA.

The effect of mupirocin- and fusidic acid-nasal packings, placed after septoplasty, on the nasal bacterial profile

Aim:

To examine the effects, after septoplasty, of local antibiotic pomades as an alternative to prophylactic antibiotic use, which is a controversial matter among the otolaryngologists, on nasal flora and bacterial growth.

Material and Method:

Nasal packings placed after septoplasty surgery to provide septal stabilization and bleeding control pose a risk in terms of infection. In this study, 106 patients, who were examined by comparing mupirocin- and fusidic acid–soaked packings and antibiotic-free packings, were divided into three groups. Nasal cultures were obtained from each patient twice, before the surgery and on the second day immediately after the packings were removed, and the culture results were statistically compared.

Results:

In the mupirocin group (group 2), postoperative normal flora growth rate was significantly higher than in the fusidic acid group (group 3) and the antibiotic-free group (group 1) (p < 0.024). In the mupirocin group (group 2), the gram-positive growth rate in the postoperative period showed a significant decrease when compared when the preoperative period (p < 0.05) (5.7%). In the fusidic acid group (group 3), the postoperative gram-positive rate showed a significant decrease compared with the preoperative period (p < 0.05). In group 2, the postoperative methicillin-resistant Staphylococcus aureus rate showed a significant decrease than in the preoperative period (2.9%) (p < 0.05). Similarly, in group 3, the postoperative methicillin-resistant S. aureus rate showed a significant decrease compared with that of the preoperative period (11.1%) (p < 0.05).

Conclusion:

Use of mupirocin- and fusidic acid–soaked nasal packings after septoplasty significantly decreased, especially, postoperative gram-positive bacterial growth in nasal cultures. Although systemic antibiotherapy was not administered, the lack of local and systemic infection findings was an important result that we obtained in terms of clinical use. Usage advantages of mupirocin and fusidic acid soaked packings are an easily applicable, cost-effective, and safe method.

Epidemiology of Staphylococcus aureus Nasal Carriage Patterns in the Community

Staphylococcus aureus (S. aureus) is a Gram-positive opportunistic pathogen that colonizes frequently and asymptomatically the anterior nares of humans and animals. It can cause different kinds of infections and is considered to be an important nosocomial pathogen. Nasal carriage of S. aureus can be permanent or intermittent and may build the reservoir for autogenous infections and cross-transmission to other individuals. Most of the studies on the epidemiology of S. aureus performed in the past were focused on the emergence and dissemination of methicillin-resistant Staphylococcus aureus (MRSA) in healthcare settings. There are, however, a number of more recent epidemiological studies have aimed at analysing carriage patterns over time in the community settings providing new insights on risk factors for colonization and important data for the development of strategies to prevent infections. This chapter aims to give a review of current epidemiological studies on S. aureus carriage patterns in the general community and put them into perspective with recent, yet unpublished, investigations on the S. aureus epidemiology in the general population in northern Germany.

Incidence of invasive meticillin-resistant Staphylococcus aureus infections in Germany, 2010 to 2014

Voluntary surveillance systems in Germany suggest a recent decline in the incidence of infections (subsequent to at least 2010) with meticillin-resistant Staphylococcus aureus (MRSA) from various types of specimens and settings. We asked whether this decline is reflected by data from the mandatory national surveillance system for invasive MRSA infections. Our analysis is based on the population in Germany in 2010 to 2014. Cases were identified from passive reporting by microbiological laboratories of the diagnosis of MRSA from blood culture or cerebrospinal fluid. Respective clinical data were subsequently added to the notification. We calculated risk ratios (RR) between consecutive years, stratifying cases by sex, age and federal state of residence. The national incidence increased from 4.6 episodes per 100,000 persons in 2010 to 5.6 in 2012 (2011 vs 2010: RR: 1.13, 95% confidence interval (CI): 1.08–1.18; 2012 vs 2011: RR: 1.08, 95% CI: 1.04–1.13). It stagnated at 5.4 per 100,000 in 2013 (RR: 0.97, 95% CI: 0.93–1.01) before declining to 4.8 in 2014 (RR: 0.88, 95% CI: 0.84–0.91). This trend was observed in most, but not all federal states and strata of sex and age groups. Only 204 of 20,679 (1%) episodes of infection were notified as belonging to an outbreak. Our analysis corroborates previous findings that the incidence of invasive MRSA infections in Germany may be declining.

Molecular typing of toxic shock syndrome toxin-1- and Enterotoxin A-producing methicillin-sensitive Staphylococcus aureus isolates from an outbreak in a neonatal intensive care unit

Outbreaks of Staphylococcus aureus are common in neonatal intensive care units (NICUs). Usually they are documented for methicillin-resistant strains, while reports involving methicillin-susceptible S. aureus (MSSA) strains are rare. In this study we report the epidemiological and molecular investigation of an MSSA outbreak in a NICU among preterm neonates. Infection control measures and interventions were commissioned by the Local Public Health Authority and supported by the Robert Koch Institute. To support epidemiological investigations molecular typing was done by spa-typing and Multilocus sequence typing; the relatedness of collected isolates was further elucidated by DNA SmaI-macrorestriction, microarray analysis and bacterial whole genome sequencing. A total of 213 neonates, 123 healthcare workers and 205 neonate parents were analyzed in the period November 2011 to November 2012. The outbreak strain was characterized as a MSSA spa-type t021, able to produce toxic shock syndrome toxin-1 and Enterotoxin A. We identified seventeen neonates (of which two died from toxic shock syndrome), four healthcare workers and three parents putatively involved in the outbreak. Whole-genome sequencing permitted to exclude unrelated cases from the outbreak and to discuss the role of healthcare workers as a reservoir of S. aureus on the NICU. Genome comparisons also indicated the presence of the respective clone on the ward months before the first colonized/infected neonates were detected.

Differences in Staphylococcus aureus nasal carriage and molecular characteristics among community residents and healthcare workers at Sun Yat-Sen University, Guangzhou, Southern China

Background

The pathogenic potential and commensal nature of Staphylococcus aureus allows for easy transmission both within and outside of the hospital environment, and nasal carriage may be responsible for some serious infections. This study aimed to determine the molecular and epidemiological characteristics of nasal colonization by S. aureus in community residents (CR) and healthcare workers (HW) at Sun Yat-Sen University, Guangzhou, China.

Methods

A total of 589 volunteers, both CR (n = 297) and HW (n = 292), were recruited. Each subject completed a questionnaire, and specimens were obtained from the anterior nares for S. aureus screening. Genotypic analysis included pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), staphylococcal cassette chromosome mec (SCCmec) typing, and virulence gene detection.

Results

A total of 138 S. aureus isolates were recovered from separate subjects (23.4 %, 138/589), with four isolates showing methicillin resistance (0.7 %, 4/589). The prevalence of S. aureus carriage was 25.3 % (75/297) in CR and 21.6 % (63/292) in HW. Methicillin-resistant S. aureus (MRSA) were isolated from one CR (0.3 %, 1/297) and three HW (1.0 %, 3/292). The most common risk factors for S. aureus carriage in CR were being male, age ≤ 30 years, and nasal cavity cleaning habits. Having a household member in the healthcare profession was associated with increased risk among HW. Sequence type (ST)188 and ST59 were the most prevalent among the 20 observed STs, accounting for 14.6 % and 12.2 % of all isolates, respectively. The four MRSA isolates presented four different STs, with one isolate carrying a type IVa SCCmec element and the other three isolates containing type III SCCmec. PFGE analysis grouped the 129 isolates into 23 pulsotypes, with profiles A, N, E, L, and O the most prevalent. The Panton-Valentine leucocidin gene (pvl) was identified in two of the 138 isolates, while 57.5 % of isolates carried both the Staphylococcus aureus enterotoxin A (sea) and enterotoxin B (seb) genes.

Conclusions

These data indicate a low prevalence of nasal MRSA carriage but evidence of molecular heterogeneity among S. aureus isolates from CR and HW at Sun Yat-Sen University, Guangzhou. Differences in epidemiological and molecular characteristics of S. aureus between CR and HW populations may be useful for the understanding and prevention of S. aureus infection.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-015-1032-7) contains supplementary material, which is available to authorized users.