Frieder Schaumburg

Livestock-Associated Methicillin-Resistant Staphylococcus aureus (MRSA) as Causes of Human Infection and Colonization in Germany

Pigs, cattle and poultry are colonized with MRSA and the zoonotic transmission of such MRSA to humans via direct animal contact, environmental contaminations or meat are a matter of concern. Livestock-associated (LA) MRSA are mostly belonging to clonal complex (CC) 398 as defined by multilocus sequence typing. However, MRSA of other clonal lineages including CC5, CC9 and CC97 have also been detected in livestock animals in Germany. Within the framework of a Dutch-German network project (EUREGIO), 14,036 MRSA isolated from clinical and screening specimens (January 2008 - June 2012) derived from human patients in hospitals as well as general or specialized practices in a German region characterized by a high density of livestock production, were subjected to S. aureus protein A (spa) sequence typing. The prevalence of putative LA-MRSA among the human MRSA isolates was determined by analyzing the detection of livestock-indicator (LI) spa types which had already been reported in German livestock. Overall, 578 spa types were detected among the MRSA isolates. LI spa types t011, t034, t108, t1451, t2011, t571, t1456, t1250, t1255, t1580, t2970, t2346, t1344, t2576, t2330 and t2510 (all of which are indicative for LA-MRSA CC398) accounted for 18.6% of all human isolates. The LI spa types t1430 (CC9), t3992 (CC97), t002 (CC5) and t007 (CC30) were found in 0.14%, 0.01%, 1.01% and 0.04% of all human MRSA isolates, respectively. LI spa types associated with CC398 represented 23% of all MRSA from screening samples and a varying proportion among isolates from clinical specimens ranging between 0% in cerebrospinal fluid, 8% in blood cultures and 14% in deep respiratory fluids. Our findings indicate that LA-MRSA are a major cause for human infection and stress the need for close surveillance. Although LA-MRSA CC398 predominates, the occurrence of putative LA-MRSA from other clonal lineages should be monitored.

Effects of Antibiotics on Shiga Toxin 2 Production and Bacteriophage Induction by Epidemic Escherichia coli O104:H4 Strain

ABSTRACT The role of antibiotics in treatment of enterohemorrhagic Escherichia coli (EHEC) infections is controversial because of concerns about triggering hemolytic-uremic syndrome (HUS) by increasing Shiga toxin (Stx) production. During the recent large EHEC O104:H4 outbreak, antibiotic therapy was indicated for some patients. We tested a diverse panel of antibiotics to which the outbreak strain is susceptible to interrogate the effects of subinhibitory antibiotic concentrations on induction of stx2-harboring bacteriophages, stx2 transcription, and Stx2 production in this emerging pathogen. Ciprofloxacin significantly increased stx2-harboring phage induction and Stx2 production in outbreak isolates (P values of <0.001 to <0.05), while fosfomycin, gentamicin, and kanamycin insignificantly influenced them (P > 0.1) and chloramphenicol, meropenem, azithromycin, rifaximin, and tigecycline significantly decreased them (P ≤ 0.05). Ciprofloxacin and chloramphenicol significantly upregulated and downregulated stx2 transcription, respectively (P < 0.01); the other antibiotics had insignificant effects (P > 0.1). Meropenem, azithromycin, and rifaximin, which were used for necessary therapeutic or prophylactic interventions during the EHEC O104:H4 outbreak, as well as tigecycline, neither induced stx2-harboring phages nor increased stx2 transcription or Stx2 production in the outbreak strain. These antibiotics might represent therapeutic options for patients with EHEC O104:H4 infection if antibiotic treatment is inevitable. We await further analysis of the epidemic to determine if usage of these agents was associated with an altered risk of developing HUS.

Population Dynamics among Methicillin-Resistant Staphylococcus aureus Isolates in Germany during a 6-Year Period

ABSTRACT Methicillin-resistant Staphylococcus aureus (MRSA) originated from the health care setting but is now emerging in communities without health care contact (CA-MRSA) or in livestock (LA-MRSA). The impact on the whole MRSA population was assessed in a German prospective multicenter study. Thirty-three laboratories consecutively collected up to 50 MRSA isolates from infection or carriage during two sampling periods in 2004 to 2005 and 2010 to 2011. Patient-related data were collected using a standardized questionnaire. Methicillin resistance was confirmed by the detection of mecA or its homologue mecA LGA251. The spa type and major virulence factors were analyzed for each isolate. In total, 1,604 (2004 to 2005) and 1,603 (2010 to 2011) MRSA isolates were analyzed; one isolate from each sampling period harbored mecA LGA251. LA-MRSA increased significantly (odds ratio [OR] = 22.67, 95% confidence interval [CI] = 8.51 to 85.49, P < 0.0005) and spread over Germany, originating from northwestern regions. Panton-Valentine leukocidin-positive CA-MRSA rose significantly, particularly in southern Germany, but the proportion in 2010 to 2011 remained low (2.7%, OR = 2.80, 95% CI = 1.54 to 5.34, P < 0.0005). The emerging MRSA clones changed the MRSA population in Germany during a 6-year period significantly. The ongoing epidemiological shift and changes of MRSA sources create a need for revision of guidelines for MRSA infection control and treatment.

Comparing the anterior nare bacterial community of two discrete human populations using Illumina amplicon sequencing

The anterior nares are an important reservoir for opportunistic pathogens and commensal microorganisms. A barcoded Illumina paired-end sequencing method targeting the 16S ribosomal RNA V1-2 hypervariable region was developed to compare the bacterial diversity of the anterior nares across distinct human populations (volunteers from Germany vs a Babongo Pygmy tribe, Africa). Of the 251 phylotypes detected, 231 could be classified to the genus level and 109 to the species level, including the unambiguous identification of the ubiquitous Staphylococcus aureus and Moraxella catarrhalis. The global bacterial community of both adult populations revealed that they shared 85% of the phylotypes, suggesting that our global bacterial communities have likely been with us for thousands of years. Of the 34 phylotypes unique to the non-westernized population, most were related to members within the suborder Micrococcineae. There was an even more overwelming distinction between children and adults of the same population, suggesting a progression of a childhood community of high-diversity comprising species of Moraxellaceae and Streptococcaceae to an adult community of lower diversity comprising species of Propionibacteriaceae, Clostridiales Incertae Sedis XI, Corynebacteriaceae and Staphylococcaceae. Thus, age was a stronger factor for accounting for differing bacterial assemblages than the origin of the human population sampled.

Virulence factors and genotypes of Staphylococcus aureus from infection and carriage in Gabon

Staphylococcus aureus isolates from developed countries have been extensively analyzed with respect to their virulence patterns and clonal relatedness but there is only sparse information on the molecular diversity of S. aureus isolates from Africa. In particular, little is known about S. aureus isolates from asymptomatic carriers compared with isolates causing infections. From 2008 to 2010, we prospectively collected S. aureus isolates from asymptomatic carriers and infections in Lambaréné, Gabon, Central Africa. For these isolates, we determined major virulence factors, and performed multilocus sequence typing (MLST) and spa typing. Among 163 S. aureus isolates from asymptomatic carriers, we found the MLST clonal complexes (CCs) 5, 6, 7, 8, 9, 15, 25, 30, 45, 88, 101, 121 and 152; 3.7% were methicillin-resistant (MRSA). The clinical isolates were associated with CCs 5, 8, 9, 15, 88, 121 and 152; 11% were MRSA. Sequence types 1 and 88 were significantly associated with infection and sequence type 508 was associated with carriage. Remarkably, there was a high prevalence of Panton-Valentine leukocidin (PVL) -encoding genes both in disease-related isolates (57.4%) and in carrier isolates (40.5%). We found differences in the clonal structure and virulence pattern of Gabonese S. aureus isolates from asymptomatic carriers and infections. Of note, S. aureus isolates from Gabon show a very high prevalence of PVL-encoding genes, which exceeds the rates observed for developed countries.

The Epidemiology of Methicillin-Resistant Staphylococcus aureus (MRSA) in Germany

BACKGROUND For decades, methicillin-resistant Staphylococcus aureus (MRSA) has been a major cause of infection in hospitals and nursing homes (health care-associated MRSA, HA-MRSA). Beginning in the late 1990s, many countries have also experienced a rising incidence of MRSA infection outside of the health care setting (community-associated MRSA, CA-MRSA). Moreover, animal reservoirs are increasingly considered to represent an important source of human MRSA acquisition. In this review article the authors describe the current epidemiological situation of MRSA in Germany. METHODS This review is based on pertinent articles published up to 2010 that were retrieved by a selective PubMed search, as well as on publications issued by national reference institutions up to 2010. RESULTS There are about 132 000 cases of MRSA in German hospitals each year. MRSA is found in about 18% to 20% of all inpatient-derived culture specimens that are positive for S. aureus. CA-MRSA is not yet endemic in Germany; important risk factors for its acquisition include travel to high-prevalence areas and household contact with persons that harbor a CA-MRSA infection. Agricultural livestock is the main animal reservoir for MRSA, which is often zoonotically transmitted from animals to human beings by direct contact. However, both CA-MRSA and MRSA from animal reservoirs can be imported into hospitals and cause nosocomial infections. CONCLUSION Hospitals and nursing homes were once the main reservoirs of MRSA, but new ones have now emerged outside of the healthcare setting. Efforts to prevent MRSA and limit its spread must rise to this new challenge.

Novel staphylococcal species that form part of a Staphylococcus aureus-related complex: the non-pigmented Staphylococcus argenteus sp. nov. and the non-human primate-associated Staphylococcus schweitzeri sp. nov.

We define two novel species of the genus Staphylococcusthat are phenotypically similar to and have near identical 16S rRNA gene sequences to Staphylococcus aureus. However, compared to S. aureus and each other, the two species, Staphylococcus argenteus sp. nov. (type strain MSHR1132T = DSM 28299T = SSI 89.005T) and Staphylococcus schweitzeri sp. nov. (type strain FSA084T = DSM 28300T = SSI 89.004T), demonstrate: 1) at a whole-genome level considerable phylogenetic distance, lack of admixture, average nucleotide identity <95 %, and inferred DNA–DNA hybridization <70 %; 2) different profiles as determined by MALDI-TOF MS; 3) a non-pigmented phenotype for S. argenteus sp. nov.; 4) S. schweitzeri sp. nov. is not detected by standard nucA PCR; 5) distinct peptidoglycan types compared to S. aureus; 6) a separate ecological niche for S. schweitzeri sp. nov.; and 7) a distinct clinical disease profile for S. argenteus sp. nov. compared to S. aureus.

Origin and Evolution of European Community-Acquired Methicillin-Resistant Staphylococcus aureus

ABSTRACT Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) was recognized in Europe and worldwide in the late 1990s. Within a decade, several genetically and geographically distinct CA-MRSA lineages carrying the small SCCmec type IV and V genetic elements and the Panton-Valentine leukocidin (PVL) emerged around the world. In Europe, the predominant CA-MRSA strain belongs to clonal complex 80 (CC80) and is resistant to kanamycin/amikacin and fusidic acid. CC80 was first reported in 1993 but was relatively rare until the late 1990s. It has since been identified throughout North Africa, the Middle East, and Europe, with recent sporadic reports in sub-Saharan Africa. While strongly associated with skin and soft tissue infections, it is rarely found among asymptomatic carriers. Methicillin-sensitive S. aureus (MSSA) CC80 strains are extremely rare except in sub-Saharan Africa. In the current study, we applied whole-genome sequencing to a global collection of both MSSA and MRSA CC80 isolates. Phylogenetic analyses strongly suggest that the European epidemic CA-MRSA lineage is derived from a PVL-positive MSSA ancestor from sub-Saharan Africa. Moreover, the tree topology suggests a single acquisition of both the SCCmec element and a plasmid encoding the fusidic acid resistance determinant. Four canonical SNPs distinguish the derived CA-MRSA lineage and include a nonsynonymous mutation in accessory gene regulator C (agrC). These changes were associated with a star-like expansion into Europe, the Middle East, and North Africa in the early 1990s, including multiple cases of cross-continent imports likely driven by human migrations. IMPORTANCE With increasing levels of CA-MRSA reported from most parts of the Western world, there is a great interest in understanding the origin and factors associated with the emergence of these epidemic lineages. To trace the origin, evolution, and dissemination pattern of the European CA-MRSA clone (CC80), we sequenced a global collection of strains of the S. aureus CC80 lineage. Our study determined that a single descendant of a PVL-positive methicillin-sensitive ancestor circulating in sub-Saharan Africa rose to become the dominant CA-MRSA clone in Europe, the Middle East, and North Africa. In the transition from a methicillin-susceptible lineage to a successful CA-MRSA clone, it simultaneously became resistant to fusidic acid, a widely used antibiotic for skin and soft tissue infections, thus demonstrating the importance of antibiotic selection in the success of this clone. This finding furthermore highlights the significance of horizontal gene acquisitions and underscores the combined importance of these factors for the success of CA-MRSA. With increasing levels of CA-MRSA reported from most parts of the Western world, there is a great interest in understanding the origin and factors associated with the emergence of these epidemic lineages. To trace the origin, evolution, and dissemination pattern of the European CA-MRSA clone (CC80), we sequenced a global collection of strains of the S. aureus CC80 lineage. Our study determined that a single descendant of a PVL-positive methicillin-sensitive ancestor circulating in sub-Saharan Africa rose to become the dominant CA-MRSA clone in Europe, the Middle East, and North Africa. In the transition from a methicillin-susceptible lineage to a successful CA-MRSA clone, it simultaneously became resistant to fusidic acid, a widely used antibiotic for skin and soft tissue infections, thus demonstrating the importance of antibiotic selection in the success of this clone. This finding furthermore highlights the significance of horizontal gene acquisitions and underscores the combined importance of these factors for the success of CA-MRSA.

Population structure of Staphylococcus aureus from remote African Babongo Pygmies

Background Pandemic community-acquired methicillin-resistant Staphylococcus aureus isolates (CA-MRSA) predominantly encode the Panton-Valentine leukocidin (PVL), which can be associated with severe infections. Reports from non-indigenous Sub-Saharan African populations revealed a high prevalence of PVL-positive isolates. The objective of our study was to investigate the S. aureus carriage among a remote indigenous African population and to determine the molecular characteristics of the isolates, particularly those that were PVL-positive. Methodology/Principal Findings Nasal S. aureus carriage and risk factors of colonization were systematically assessed in remote Gabonese Babongo Pygmies. Susceptibility to antibiotics, possession of toxin-encoding genes (i.e., PVL, enterotoxins, and exfoliative toxins), S. aureus protein A (spa) types and multi-locus sequence types (MLST) were determined for each isolate. The carriage rate was 33%. No MRSA was detected, 61.8% of the isolates were susceptible to penicillin. Genes encoding PVL (55.9%), enterotoxin B (20.6%), exfoliative toxin D (11.7%) and the epidermal cell differentiation inhibitor B (11.7%) were highly prevalent. Thirteen spa types were detected and were associated with 10 STs predominated by ST15, ST30, ST72, ST80, and ST88. Conclusions The high prevalence of PVL-positive isolates among Babongo Pygmies demands our attention as PVL can be associated with necrotinzing infection and may increase the risk of severe infections in remote Pygmy populations. Many S. aureus isolates from Babongo Pygmies and pandemic CA-MRSA-clones have a common genetic background. Surveillance is needed to control the development of resistance to antibiotic drugs and to assess the impact of the high prevalence of PVL in indigenous populations.

New epidemiology of Staphylococcus aureus infection in Africa

Research on African Staphylococcus aureus has been largely neglected in the past, despite the cultural and geographical diversity in Africa, which has a significant impact on the epidemiology of this pathogen. The polarity between developed urban societies and remote rural populations (e.g. Pygmies), combined with close contact with animals (e.g. livestock and domestic animals, and wildlife), makes the epidemiology of S. aureus on the African continent unique and fascinating. Here, we try to draw an epidemiological picture of S. aureus colonization and infection in Africa, and focus on the wide spread of Panton-Valentine leukocidin-positive isolates, the emergence of the hypervirulent methicillin-resistant S. aureus (MRSA) clone USA300, and the dissemination of the typical African clone MRSA sequence type 88.