Christa Cuny

Obvious lack of association between dynamics of epidemic methicillin-resistant Staphylococcus aureus in central Europe and agr specificity groups.

During the past 8 years, changes in the prevalence and spread of different epidemic methicillin-resistant Staphylococcus aureus (MRSA) have been observed in central Europe, with the emergence of new strains possessing fewer resistance characters. This has also been demonstrated at the level of particular hospitals. Since variation in agr specificity type has been proposed as a possible reason for population dynamics in Staphylococcus aureus, the agr specificity groups of different epidemic MRSA strains were investigated by PCR using agr group-specific primers. Four of the “old” as well as two “new” epidemic strains exhibited agr specificity group I. One group of epidemic MRSA strains, which has been observed since the beginning of the 1990s, exhibited the agr specificity group II. Sequencing the variable part (agrB-D-C) of the agr locus revealed only six relevant nucleotide changes within this region, with three of them modifying the Shine-Dalgarno sequence region of agrC. On the basis of the results obtained, it is proposed that the dynamics observed in the population of MRSA in Germany is not due to different agr group specificities in “old” and “new” epidemic clones.

Changing pattern of antibiotic resistance in methicillin-resistant Staphylococcus aureus from German hospitals.

OBJECTIVE To investigate the background of changes of resistance phenotypes in methicillin-resistant Staphylococcus aureus (MRSA) from nosocomial infections in German hospitals by molecular typing and identification of particular resistance genes. METHODS Isolates from the network for monitoring the spread of MRSA in Germany were subjected to quantitative susceptibility testing, to molecular typing, and to polymerase chain reaction identification of resistance genes. PARTICIPANTS The network consists of 175 German clinical microbiological laboratories collaborating with the German Reference Center for Staphylococci, which performs typing of staphylococcal isolates from nosocomial infections and data analysis. RESULTS During the past 5 years, MRSA susceptible to other antibiotics such as oxytetracycline, erythromycin, and gentamicin became more frequent. The proportion of epidemic MRSA clones that had been disseminated in the past and that exhibited broad resistance phenotypes decreased, whereas the proportion of recently emerging MRSA carrying only a few other resistance determinants has increased (1994, 11.5%; 1998, 39%). CONCLUSIONS The changing pattern of resistance phenotypes of MRSA from nosocomial infections in Germany is mainly due to the spread of recently emerging epidemic strains that are less frequently resistant to antibacterials other than oxacillin. The observed changes cannot simply be attributed to overall antibiotic consumption.

Clonal dissemination of two MRSA strains in Germany

Clonal dissemination of two different MRSA strains, both clumping factor negative, has been observed in Germany for more than a year. Both strains possess the mec-A determinant and each exhibits a characteristic genomic DNA fragment pattern. One strain has spread in the north, the other in the south-west of Germany. Intensive care units are mainly affected by MRSA-infections and probably play a special role in further intra- and inter-hospital spread.

A database System for Fragment Patterns of Genomic DNA of Staphylococcus aureus

The increasing use of molecular fingerprints in the epidemiology of bacterial nosocomial infections urgently demands a computerised analysis and storage of corresponding patterns, especially with regard to results obtained at different times and in different laboratories. This paper presents a database system in connection with cluster analysis of clonal relations by using genomic DNA fragment patterns of S. aureus (SmaI-digestion, pulsed-field gel electrophoresis) as an example: The database is operated under MS-Access, version 2.0. The cluster analysis is based on an optimising similarity algorithm.

Analysis of nosocomial outbreaks with multiply and methicillin-resistantStaphylococcus aureus (MRSA) in Germany: Implications for hospital hygiene

SummaryTwo outbreaks of nosocomial infections with MRSA, one in a urological unit in connection with transurethral prostatectomy and the other in an orthopaedic clinic with infections after implantation of prosthetic hips, have been analyzed on the basis of typing MRSA by phagepatterns, plasmid profiles and genomic DNA fragment patterns. Main reasons for these outbreaks were obviously mistakes in hospital hygiene and an inappropriate antibiotic prophylaxis (in the first outbreak a quinolone over about 7 days, in the second a third generation cephalosporin). Both outbreaks could be stopped by measures of hospital hygiene including isolated or cohort nursing of affected patients, and change in antibiotic prophylaxis. Intensive care units (ICUs) are more often affected by MRSA than other clinical settings. As described by the example of an outbreak with MRSA in a municipal hospital, ICUs can play a special role in intrahospital spread of MRSA. The recently observed inter-regional clonal interhospital dissemination of MRSA in Germany is mainly due to a transfer of patients between hospitals; prewarning of the hospital of destination and a number of hygiene measures can prevent further spread.ZusammenfassungZwei Ausbrüche von Krankenhausinfektionen mit MRSA, im ersten Fall in einer urologischen Abteilung im Zusammenhang mit transurethraler Prostatectomy, im zweiten Fall in einer orthopädischen Klinik nach Hüftgelenkersatz, wurden auf der Grundlage der Typisierung von MRSA mittels Lysotypie, Plasmidprofilen und Fragmentmustern der genomischen DNS analysiert. Hauptursachen für diese Ausbrüche waren offensichtliche Fehler der Krankenhaushygiene und unpassende Antibiotikaprophylaxe (beim ersten Ausbruch ein Chinolon über 7 Tage, beim zweiten Ausbruch ein Drittgenerations-Cephalosporin). Beide Ausbrüche konnten durch Maßnahmen der Krankenhaushygiene, die eine Isoliertpflege der betroffenen Patienten einschlossen, und durch Änderungen der Antibiotikaprophylaxe beendet werden. Intensivpflegestationen (ICU) werden deutlich häufiger durch Infektionen mit MRSA betroffen als andere klinische Bereiche. Wie am Beispiel eines Ausbruchs mit MRSA in einem städtischen Krankenhaus beschrieben wird, können ICU eine besondere Bedeutung für die weitere Ausbreitung von MRSA in einem Krankenhaus haben. Die gegenwärtig in Deutschland beobachtete überregionale klonale Ausbreitung von MRSA ist vorrangig auf die Verlegung von Patienten zwischen Krankenhäusern zurückzuführen. Eine Vorwarnung in Verbindung mit rechtzeitig getroffenen Hygienemaßnahmen kann die weitere Ausbreitung verhindern.

The impact of zoonotic MRSA colonization and infection in Germany

Methicillin-resistant Staphylococcus aureus (MRSA) causes colonization and infection both in animals and humans. In Germany, cases of MRSA colonization among humans, w+hich affect 0.5-1.5% of the general population and 1.0-2.5% of patients at hospital admission, are still mostly associated with previous healthcare contact and defined epidemic clonal lineages. However, MRSA is also distributed in livestock production in Germany, mostly without causing infections in the animals. These MRSA predominantly belong to the clonal complex (CC) 398, but also to CC9 and CC97. Zoonotic transmission of MRSA CC398 from livestock to humans occurs predominantly in people with occupational livestock contact. Spread of MRSA CC398 to household members of these persons is also frequently observed, but dissemination in the general population is limited so far However, especially in areas with intensive livestock husbandry, about 20-38% of MRSA CC398 cases among humans cannot be epidemiologically linked to direct livestock contact, indicating other transmission pathways. MRSA CC398 currently causes about 2% of all human MRSA infections (wound infections, pneumonia, sepsis) in Germany, but up to 10% in regions characterized by a high density of livestock-farming. The burden of MRSA in companion animals was demonstrated to range between 3.6-9.4% within wound samples obtained from dogs, cats and horses, respectively. In contrast to livestock and horses, MRSA distributed in pet animals are mostly associated with MRSA clonal lineages that are also prevalent in human healthcare facilities. Overall, zoonotic exchange of MRSA between humans and animals has relevant impact on the epidemiology of MRSA in Germany.

State-wide surveillance of antibiotic resistance patterns and spa types of methicillin-resistant Staphylococcus aureus from blood cultures in North Rhine-Westphalia, 2011-2013

Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of bacteraemia. We aimed to obtain a complete picture of severe MRSA infections by characterizing all MRSA isolates from bloodstream infections in the largest German federal state (North Rhine-Westphalia, 18 million inhabitants) using S. aureus protein A (spa) sequence-typing and antimicrobial susceptibility testing. MRSA isolates (n = 1952) were collected prospectively (2011-2013) and spa-typed. Among 181 different spa types, t003 (n = 746 isolates; 38.2%) and t032 (n = 594; 30.4%) were predominant. Analysis of the geographical occurrence of spa clonal complexes (spa-CCs) and spa types revealed divergent distribution between federal state districts for spa-CCs 003 (p < 0.001; including t003, p < 0.001 and t264, p < 0.001), 008 (p 0.021), 011 (p 0.002), 032 (p < 0.001; including t022, p 0.014 and t032, p < 0.001) and spa type t2807 (p < 0.001). MICs of antimicrobial substances were tested using broth microdilution. Of all isolates, 96% were resistant to fluoroquinolones, 78% to erythromycin, 70% to clindamycin, 4% to gentamicin, 2% to rifampicin, 0.4% to daptomycin, 0.1% to linezolid and 0% to vancomycin, respectively. Vancomycin MICs of 2 mg/L involved 0.5% of the isolates. In conclusion, the detection of regional molecular clusters added valuable information for epidemiological case tracing and allowed conclusions to be reached on the importance of newly emerging MRSA reservoirs, such as livestock (spa-CC011), for MRSA bacteraemia in some parts of the federal state. Susceptibility testing revealed broad resistance to substances used for oral treatment, but demonstrated that those antibiotics that are mostly applied for treatment of MRSA bacteraemia and important combination partners were highly susceptible.

Discrimination of S. aureus Strains by PCR for r-RNA Gene Spacer Size Polymorphism and Comparison to SmaI Macrorestriction Patterns

The size polymorphism of the internal spacer between the 16 S and the 23 S r-RNA genes was studied in S. aureus with the aid of PCR. The patterns of corresponding PCR products were compared with SmaI-generated macrorestriction patterns for definite propagating strains of S. aureus typing phages, for strains with phage pattern 29, phage-group II patterns, phage pattern 94, 96, phage pattern 95 and epidemic methicillin-resistant strains (MRSA). The spacer length polymorphism did not prove to be as discriminative as genomic DNA fragment patterns. However, as shown for S. aureus with phage patterns 29; group II; 94, 96; 95 and also for 4 out of 6 epidemic MRSA, unique patterns of r-RNA gene spacers probably indicate a relatedness among strains which is also suggested by SmaI macrorestriction patterns.

Stability of genomic DNA fragment patterns in methicillin resistant Staphylococcus aureus (MRSA) during the course of intra- and interhospital spread

The analysis of genomic DNA fragment patterns has revealed as a powerful tool for strain discrimination inStaphylococcus aureus; for use as an epidemiological marker, stability during the course of an outbreak is an essential prerequisite. Genomic DNA fragment patterns (SmaI restriction, pulsed-field electrophoresis) of four different epidemic MRSA strains were compared along with intra- and interhospital and country-wide spread over more than 12 months in Germany. Strain I was isolated from infections in 8 hospitals. In one hospital a subclone arised which differed from the original strain by 4 fragments. Strain II was spread among 4 hospitals, isolates from three of these hospitals exhibited a variability of one to three fragments in the 150–200 kb range. Two hospitals in the Hannover-area were affected by strain III; in 17 isolates of this strain a variability up to three fragments was found in the 170–200 kb range. Strain IV was isolated from 19 cases of infections in 3 hospitals in Berlin. The fragment patterns were completely stable. When S. aureus strains are typed by genomic DNA fragment patterns, a variability in a definite range of molecular masses during the course of an epidemic should be taken into consideration.

Characterization of methicillin-resistant Staphylococcus aureus from Ulaanbaatar, Mongolia

In order to expand current knowledge of the types of methicillin-resistant Staphylococcus aureus (MRSA) strains circulating in central Asia, six MRSA strains collected from hospitals in Ulaanbaatar, Mongolia during 2000–2002 were examined. Three strains possessed a staphylococcal cassette chromosome mec (SCCmec) element of type IV c, were sequence type (ST) 154 according to multilocus sequence typing (MLST), and contained lukS–lukF (Panton–Valentine leukocidin). Another three strains contained a SCCmec element of type III and were MLST type ST 239. Using automated ribotyping, the six MRSA strains were divided into four different EcoRI ribotypes, and two groups of isolates were distinguished by means of SmaI-macrorestriction patterns. In comparison to other countries, the incidence of MRSA in Mongolia is low.