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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. [ABSTRACT FROM AUTHOR]

MRSA infections in equine clinics were reported from Northern America, Europe, Australia, and Japan. The majority of nosocomial infections in horses is obviously associated with particular MRSA clonal lineages. As already observed for epidemic MRSA in human hospitals more than 10 years ago, a dynamics of MRSA clonal lineages is also observed in European equine clinics: clonal lineages belonging to clonal complex (CC) 8 are on the retreat whereas MRSA attributed to CC398 become increasingly prevalent. The majority of CC398 isolates belong to a subpopulation which is particularly associated with equine hospitals as indicated by molecular typing. When emerging in equine clinics, MRSA from horses were also found as nasal colonizers of veterinary personnel. MRSA exhibiting the typing characteristics of MRSA known from equine clinics are obviously rare among MRSA from infections in humans. Although rare so far epidemic MRSA from human hospitals (HA-MRSA, e.g., ST22, ST225) have been isolated from nosocomial infections in horses and need particular attention in further surveillance. [ABSTRACT FROM AUTHOR]

Abstract: Livestock-associated Staphylococcus aureus (LA-MRSA) are mainly associated with the clonal complex (CC) 398. Although having its main reservoir as MRSA in livestock such as pigs, poultry or cattle LA-MRSA CC398 has no pronounced host specificity and can colonize or infect other animals such as horses and dogs and also humans. In German conventional farming systems nasal colonization of the animals and of humans occupationally exposed to them (up to 86%) are frequent. Further human-to-human dissemination in households occurs more rarely in general (∼4% of humans living on farms but without occupational exposition). Nasal colonization with LA-MRSA of humans at hospital admission is found in 0.08–0.2% for Germany in general. However, this proportion is higher in areas with a high density of livestock production such as in northwestern North Rhine-Westphalia or Lower Saxony. LA-MRSA CC398 is not less pathogenic for humans than S. aureus in general. Hence, LA-MRSA accounts for ∼15% of all MRSA isolates from deep-seated skin and soft-tissue infections in the community and for about 0.8–2% of all MRSA isolated from clinical specimens obtained in hospital settings. When introduced into the hospital it can cause postoperative wound infections and even septicemia. Differently from hospital-associated MRSA clones, LA-MRSA CC398 has obviously limited capacity to spread in the nosocomial setting so far (proportion of ∼1.8% among MRSA from nosocomial infections, the proportion among MRSA from blood cultures is ∼1%). [Copyright &y& Elsevier]

Abstract: While flagella-independent motility has long been described in representatives of the genus Acinetobacter, the mechanism of motility remains ambiguous. Acinetobacter baumannii, a nosocomial pathogen appearing increasingly multidrug-resistant, may profit from motility during infection or while persisting in the hospital environment. However, data on the frequency of motility skills among clinical A. baumannii isolates is scarce. We have screened a collection of 83 clinical A. baumannii isolates of different origin and found that, with the exception of one isolate, all were motile on wet surfaces albeit to varying degrees and exhibiting differing morphologies. Screening a collection of transposon mutants of strain ATCC 17978 for motility defects, we identified 2 akinetic mutants carrying transposon insertions in the dat and ddc gene, respectively. These neighbouring genes contribute to synthesis of 1,3-diaminopropane (DAP), a polyamine ubiquitously produced in Acinetobacter. Supplementing semi-solid media with DAP cured the motility defect of both mutants. HPLC analyses confirmed that DAP synthesis was abolished in ddc and dat mutants of different A. baumannii isolates and was re-established after genetic complementation. Both, the dat and ddc mutant of ATCC 17978 were attenuated in the Galleria mellonella caterpillar infection model. Taken together, surface-associated motility is a common trait of clinical A. baumannii isolates that requires DAP and may play a role in its virulence. [Copyright &y& Elsevier]

Abstract: Tracing the spatial spread of pathogens is a key objective of molecular infectious disease epidemiology. Accordingly, a wide range of genotyping approaches have been used to monitor the dissemination of Staphylococcus aureus strains, from localized outbreaks to global spread. We provide a critical review of available methods, revealing that molecular markers currently in use for typing S. aureus acquire changes so slowly that they monitor evolutionary change over timescales that are largely irrelevant to epidemiology. Moreover, the more variable markers frequently do not reflect the pathogen''s evolutionary history and, hence, provide potentially misleading information about spread. More recent work has demonstrated that staphylococcal evolution proceeds sufficiently fast that the dynamics of S. aureus spatial spread can be elucidated at great detail on the basis of genome-wide single-nucleotide polymorphisms. [Copyright &y& Elsevier]

Abstract: Enterococcus faecium is considered to be a nosocomial pathogen with increasing medical importance. The putative virulence factor, hyl Efm , encoding a putative hyaluronidase, is enriched among the hospital-associated polyclonal subpopulation of E. faecium.. The hyl Efm gene is described to be part of a genomic island and was recently identified to be plasmid-located. Here, we present a description of the structure, localization, and distribution of the putative pathogenicity factor hyl Efm and its putative island among 39 clinical isolates and elucidate the composition and host range of pLG1, a hyl Efm multiresistance plasmid of approximately 281.02kb. The hyl Efm gene was located within a 17,824-bp element highly similar to the putative genomic island (GI) structure that had been previously described. This genomic region was conserved among 39 hyl Efm -positive strains with variation in a specific region downstream of hyl Efm in 18 strains. The putative hyl Efm was located on large plasmids (150–350kb) in 37 strains. pLG1 could be horizontally transferred into four different E. faecium recipient strains (n =4) but not into E. faecalis (n =3). Sequencing of pLG1 resolved putative plasmid replication, conjugation, and maintenance determinants as well as a pilin gene cluster, carbon uptake and utilization genes, heavy metal and antibiotic resistance clusters. The hyl Efm transferable plasmid pLG1 bears additional putative pathogenicity factors and antibiotic resistance genes. These findings suggest horizontal gene transfer of virulence factors and antibiotic resistance gene clusters by a single genetic event (conjugative transfer) which might be triggered by heavy antibiotic use common in health care units where E. faecium is increasingly prevalent. [ABSTRACT FROM AUTHOR]

Abstract: During the past 15 years, emergence and dissemination of β-lactam resistance in nosocomial Enterobacteriaceae, Pseudomonas aeruginosa and Acinetobacter baumannii, became a serious problem worldwide. Especially the increasing resistance to 3rd and 4th generation cephalosporins and carbapenems is of particular concern. Gram-negative bacteria pursue various molecular strategies for development of resistance to these antibiotics: (a) generation of extended-spectrum β-lactamases (ESBL) according to the original definition due to extension of the spectrum of already widely disseminated plasmid-encoded β-lactamases by amino acid substitution; (b) acquisition of genes encoding ESBL from environmental bacteria as, for instance the CTX-M-type β-lactamases from Kluyvera spp.; (c) high-level expression of chromosome-encoded β-lactamase (bla) genes as bla OXA or bla ampC genes due to modifications in regulatory genes, mutations of the β-lactamase promoter sequence as well as integration of insertion sequences containing an efficient promoter for intrinsic bla genes; (d) mobilization of bla genes by incorporation in integrons and horizontal transfer into other Gram-negative species such as the transfer of the ampC gene from Citrobacter freundii to Klebsiella spp.; (e) dissemination of plasmid-mediated carbapenemases as KPC and metallo-β-lactamases, e.g. VIM and IMP; (f) non-expression of porin genes and/or efflux pump-based antibiotic resistance. This mini-review summarizes the historical emergence of β-lactam resistance and β-lactamases as major resistance mechanism in enteric bacteria, and also highlights recent developments such as multidrug- and carbapenem resistance. [ABSTRACT FROM AUTHOR]

Abstract: The emergence of methicillin-resistant Staphylococcus aureus (MRSA) in animals such as horses, pet animals and productive livestock has raised questions of a probable human origin and in more general of host specificity of S. aureus. Particular clonal lineages are obviously specific for humans (e.g. ST15, ST25, ST45) and other for ruminants (e.g. ST151). MRSA associated with veterinary nosocomial infections (e.g. ST8 and ST254 in horses, ST22 in small animals) very likely have their origin in health care facilities. MRSA ST398 which became first known from widespread colonization in industrially raised pigs seems to have a limited host specificity and is able to colonize and to cause infections in various hosts. Mechanisms of host adaptation and their genomic background are poorly understood so far. [Copyright &y& Elsevier]

Abstract: Results of national and international surveillance studies revealed increasing rates of vancomycin-resistant Enterococcus faecium (VREF) among German hospital patients since 2003. To investigate the molecular background of vanA-type glycopeptide resistance, 51 clinical VREF isolated between 2004 and 2006 and originating from 19 German hospitals representing 10 Federal States have been investigated. Isolates were characterised by multi-locus sequence typing (MLST), SmaI macrorestriction analysis in pulsed-field gel electrophoresis (PFGE), and multiple-locus variable-number tandem repeat analysis (MLVA). Phylogenetic relatedness between strains was identified using BioNumerics and eBURST software. Distribution of virulence markers esp and hylEfm was investigated by PCR. The structure of the vanA gene clusters was investigated by PCR, long-template PCR, sequencing and Southern hybridisations. The 51 VREF were rather diverse constituting different strain types, different virulence markers and vanA clusters. Within this diversity we found supportive data for a dissemination of related – already vancomycin-resistant –E. faecium among various hospitals and Federal States and for spread of identical vanA gene clusters among clonally different strain types within single hospitals. In conclusion, the increase in the rates of VREF among German hospital patients within the last 2 years might be rather complex and due to different molecular events and scenarios. [Copyright &y& Elsevier]

Abstract: Development of multiple resistances to antibiotics in staphylococci, enterococci and pneumococci became a health threat during the past 20 years, not only with respect to nosocomial infections. This resistance development is based on acquisition of resistance genes by predominant epidemic subpopulations (clonal complexes). Although emergence and spread of methicillin-resistant Staphylococcus aureus is associated with a limited number of epidemic clones which have been widely disseminated, acquisition of SCCmec elements by susceptible ancestors has taken place at different times and at different locations. Among Staphylococcus epidermidis and Enterococcus faecium, one clonal complex, which had acquired resistance genes at several occasions, is widely disseminated in hospitals. Also in Streptococcus pneumoniae, antibiotic resistance is preferentially associated with clonal lineages which have a capacity for spreading. They became, however, more rare after introduction of the 7-valent conjugate vaccine. [Copyright &y& Elsevier]

Abstract: The new semi-synthetic streptogramin antibiotic combination quinupristin/dalfopristin (Synercid®) is a promising alternative for a treatment of infections with multiple resistant gram-positive pathogens, e.g. glycopeptide- and multi-resistant Enterococcus faecium. Streptogramins consist of two unrelated compounds, a streptogramin A and B, which act synergistically when given in combination. Mechanisms conferring resistance against both components are essential for resistance against the combination in E. faecium. In this species resistance to streptogramin A compounds is mediated via related acetyltransferases VatD and VatE. Resistance against streptogramins B is either encoded by the widespread ermB gene cluster conferring resistance to macrolide-lincosamide-streptogramin B antibiotics or via expression of the vgbA gene, which encodes a staphylococcal-type lactonase. E. faecalis is intrinsically resistant to streptogramins.Due to a wide use of streptogramins (virginiamycins S/M) in commercial animal farming a reservoir of streptogramin-resistant E. faecium isolates had already been selected. Determinants for streptogramin resistance are localized on plasmids that can be transferred into an E. faecium recipient both in vitro in filter-matings and in vivo in the digestive tracts of rats. Hybridization and sequencing experiments revealed a linkage of resistance determinants for streptogramins A and B on definite plasmid fragments. [Copyright &y& Elsevier]

Studies a group of atopic dermatitis (AD) patients for the presence of staphylococcus aureus on the lesional skin as well as for colonization of the vestibulum nasi. Macrorestriction patterns of S. aureus; Molecular typing of S. aureus; S. aureus colonization rate observed in children; Causative role of superantigens in AD; Extracellular product and polymerase chain reaction for the corresponding genetic determinants.

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 38–40 kb. 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. [ABSTRACT FROM AUTHOR]

There are only few data on the persistence and transmission of methicillin resistant Staphylococcus aureus (MRSA) of the clonal complex (CC) 398 among veterinarians and their household members. We therefore investigated the long-term colonisation with MRSA CC398 among participants of veterinary conferences in Germany in 2008/2009 and their household members. Forty-five initially MRSA CC398 positive and 180 initially MRSA CC398 negative conference participants were included in a longitudinal study. These persons and their household members were tested for nasal colonisation in 2011, 2012 and 2014. Of 31 continuously tested and initially MRSA CC398 positive participants only 8 (26%) were colonized with MRSA CC398 at all 4 time points, 4 (13%) of them consistently with the same spa type. Among initially MRSA CC398 negative participants, 13 (7%) were tested MRSA CC398 positive at least once during the follow-up period. Data for household members at least at one time point were available for 185 households. Of these 21 (11%) households had one or more household member who tested positive for MRSA CC398 at least once. The odds of household members to be MRSA CC398 positive was 12 times higher (95% confidence interval 4–37) when the conference participant tested MRSA CC398 positive in 2008/2009. This association remained strong when household members working in veterinary medicine or livestock farms were excluded. In summary, these data suggest that colonisation with MRSA CC398 is partially transient and that household members of MRSA CC398 colonized persons are at an increased risk of colonisation with MRSA CC398. [ABSTRACT FROM AUTHOR]

Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) isolates of clonal complex 398 (CC398) are frequently found in Europe, and recent studies highlighted the importance of mobile genetic element (MGE) exchange for host adaptation of this lineage. Of note, one of the MGEs commonly found in human S. aureus isolates, the immune evasion cluster (IEC) harboring bacteriophage Sa int 3, is very rarely found in LA-MRSA CC398 isolates obtained from farm animals, but more frequently found in LA-MRSA CC398 that were retransmitted to humans. Here, we analyzed with a set of S. aureus CC398 isolates harboring/lacking φSa int 3 how this MGE affects (i) phagocytosis of CC398 isolates by polymorphonuclear neutrophils (PMNs), and (ii) hemolysis of human and livestock-derived erythrocytes. Isolates lacking φSa int 3 were more efficiently phagocytosed by human PMNs in whole blood phagocytosis assays than isolates harboring this bacteriophage, irrespective of their origin. Notably, a similar effect was observed when equine blood was utilized, but not detected with porcine blood. Integration of φSa int 3 into LA-MRSA CC398 strains lacking this MGE confirmed these findings, as φSa int 3-harboring recipients were again less efficiently ingested by PMNs in equine and human blood than their parental strains. Integration of φSa int 3 strongly reduced the hemolytic potential of the culture supernatants against human-derived erythrocytes, and to a smaller extent also against porcine-derived erythrocytes, while φSa int 3 integration only slightly affected the hemolytic capacities against equine-derived red blood cells. The significant protective effect of φSa int 3 against phagocytosis by equine PMNs suggests that the host specificity of the IEC components might be broader than currently assumed. [ABSTRACT FROM AUTHOR]

The immune evasion gene cluster (IEC) is typical for Staphylococcus aureus isolated from humans but is usually absent in S. aureus isolated from animals. Previous studies have shown that methicillin resistant S. aureus (MRSA) CC398 obviously lost the IEC when evolving as livestock-associated MRSA from a human-adapted, methicillin-susceptible ancestor. This study aimed to look for the presence of IEC in MRSA from pigs and horses as well as from the colonization of humans with occupational animal contact and from infections in humans. For comparison, methicillin susceptible S. aureus (MSSA) isolates from infections in humans were included. We did not detect the IEC among 94 isolates from the nasal colonization of pigs; however, the IEC was found in 6 of 61 isolates from nosocomial infections in horses. MRSA CC398 isolates from the nasal colonization of 138 pig farmers were negative for the IEC. It was detected, however, in 4 of 69 veterinarians treating horses. Among 99 epidemiologically unrelated MRSA isolates attributed to CC398 originating from infections in humans, 19 were positive for the IEC. Only three of these isolates which also contained luk -PV were attributed to the ancestral, human-adapted subpopulation of CC398 by means of PCR for detection of canonical SNPs. A considerable proportion of LA-MRSA CC398 attributed to the animal subpopulation and originating from infections in humans had acquired the IEC; this acquisition is, however, obviously not a prerequisite to the capacity of LA-MRSA CC398 to cause infections in this host. Among 15 MSSA CC398 isolates from infections in humans, 11 contained the IEC, and of these, two were attributed to the animal subpopulation. Six isolates containing both the IEC and luk -PV were attributed to the ancestral, human subpopulation. Re-acquisition of the IEC by LA-MRSA CC398 suggests readaptation to the human host. In epidemiological surveillance, discrimination from the ancestral human subpopulation is important. [ABSTRACT FROM AUTHOR]

Objectives Participant-collected serial nasal swabs would be a cost-efficient feature of prospective population-based microbiological studies. We examined the feasibility of serial anterior nasal self-swabbing for Staphylococcus aureus detection in a prospective population-based study in Braunschweig, Germany, and assessed the impact of three interventions on participation and compliance. Methods Two thousand twenty-six inhabitants were selected randomly from the resident registries and asked to self-collect a nasal swab monthly from July 2012 to January 2013 and return it by mail. The swabs were tested for the presence of S. aureus. Participation and compliance were assessed in four study groups (incremental cash incentive, participation in a lottery, reminder by mail, and control group without incentive or reminder). Results Baseline participation was highest in the cash incentive group (24%; 123/504) and lowest in the reminder group (16%; 83/509). Approximately 90% of the participants in all groups returned the swabs each month, demonstrating high compliance irrespective of the intervention. Laboratory analyses showed that most swabs were usable for bacteriological studies. S. aureus was detected at the expected frequency of 20-27%. Conclusions Home-based serial nasal self-swabbing proved to be feasible and highly acceptable and promises to be a cost-efficient tool for large-scale prospective population-based studies on bacterial infection or colonization. [ABSTRACT FROM AUTHOR]

Abstract: Frequencies of vanB-type Enterococcus faecium increased in Europe during the last years. VanB enterococci show various levels of vancomycin MICs even below the susceptible breakpoint challenging a reliable diagnostics. The performance of 3 chromogenic vancomycin-resistant enterococci (VRE) screening agars, 2 Etest® vancomycin protocols, and different microdilution methods to detect 129 clinical vanB E. faecium strains was investigated. Altogether, 112 (87%) were correctly identified as VanB-type Enterococcus by microdilution MICs. An Etest® macromethod protocol was more sensitive than the standard protocol while keeping sufficient specificity in identifying 15 vanA/vanB-negative strains. Three chromogenic VRE agars performed similarly with 121 (94%), 123 (95%), and 124 (96%) vanB isolates that grew on Brilliance TM VRE Agar, CHROMagarTM VRE, and chromIDTM VRE agar, respectively. Using identical media and conditions, we did not identify different growth behaviour on agar and in broth. A few vanB strains showed growth of microcolonies inside the Etest® vancomycin inhibition zones, suggesting a VanB heteroresistance phenotype. [Copyright &y& Elsevier]

Abstract: Fast and reliable diagnostics of vancomycin-resistant enterococci (VRE) is an important prerequisite for containing VRE transmission rates and controlling VRE outbreaks among hospital patients. The BD GeneOhm™ VanR Assay (Becton Dickinson Diagnostics, Erembodegem, Belgium) is a real-time polymerase chain reaction (PCR) assay for screening perianal/rectal samples for the presence of vanA or vanB genes that can be associated with VRE. A set of 51 reference strains (vanA–G genotypes) were correctly identified. Performance of the assay was evaluated and compared with culture-based methods and subsequent PCR analysis in 2 university hospitals with a different VRE prevalence. A total of 1786 samples were analyzed. With the use of the BD GeneOhm™ VanR Assay, 88 of 102 vanA-positive specimens, 62 of 67 vanB-positive specimens, 3 of 4 vanA- and vanB-positive specimens, and 1403 of 1613 negative specimens were correctly identified. The overall sensitivity was 93.1%; the specificity was 87.0% mainly due to false-positive vanB results. Results did not differ between study institutions. [Copyright &y& Elsevier]

Abstract: Staphylococcus aureus is a common cause of bovine mastitis that is responsible for the main economic loss to the dairy industry. For identification of putative, bovine-specific molecular marker a genome comparison between bovine S. aureus strain RF122 and 52 previously sequenced S. aureus isolates associated with human infections using genome viewer, annotation tool Artemis Comparison Tool (ACT), KEGG and NCBI BLAST databases was carried out. This led to the identification of 16 unique RF122 gene sequences that may be used as molecular marker to distinguish bovine from human strains. The distribution of these genes was analyzed in a collection of bovine mastitis strains from the Netherlands and human clinical isolates by PCR and Southern blotting. Only four genes within the pathogenicity island SaPIbov3 (sab1890, sab1891, sab1892, sab1893) were present in the majority of isolates from cattle but were absent from human clinical S. aureus isolates. These results suggest that there is no gene/ORF uniformly shared by all bovine S. aureus strains that could be uniformly used as a diagnostic marker gene. [ABSTRACT FROM AUTHOR]

Methicillin-resistant Staphylococcus aureus (MRSA) emerged as a community-associated pathogen (CA-MRSA) in the past 6 years. This prospective study investigated dermatology outpatients with inflammatory skin diseases, leg ulcers, and skin infections for Panton-Valentine leukocidin (PVL)-positive S. aureus, often associated with deep skin infection. In case of PVL positivity, molecular typing and PCR demonstration of resistance genes were performed. Out of 248 patients, 130 carried S. aureus, 24 being lukS-PV lukF-PV positive. Eighteen were MRSA, 11 of them belonging to the multilocus sequence typing clonal complex (CC)5, 1 to CC45, and 2/18 to CC8. Out of 18 patients, 4 were CA-MRSA containing lukS-PV lukF-PV as an important trait of CA-MRSA. Out of four CA-MRSA isolates, two were of type ST080 containing far-1 coding for fusidic acid (FUS) resistance and two were FUS sensitive (ST152 and ST001). The FUS-sensitive CA-MRSA, which corresponded to the CA-MRSA of ST001 from the United States, was detected in Germany for the first time, indicating that dermatologists are first in line to detect CA-MRSA. In contrast to CA-MRSA from other continents, far-1-coded FUS resistance represents a typical marker for the widespread CA-MRSA ST080 in Europe, especially in Germany. The significant risk factor for the acquisition of CA-MRSA was visits to foreign countries and/or professional or private contacts with foreigners.JID JOURNAL CLUB ARTICLE: For questions, answers, and open discussion about this article, please go to http://network.nature.com/group/jidclubJournal of Investigative Dermatology (2008) 128, 2655–2664; doi:10.1038/jid.2008.133; published online 3 July 2008 [ABSTRACT FROM AUTHOR]