[Pathogen resistance--differences in epidemiology].
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Cross Infection↗
Biomedical subjects
W Witte
Publications and source records attributed to W Witte.
Characteristics of a new epidemic MRSA in Germany ancestral to United Kingdom EMRSA 15.
In 1996 a new epidemic MRSA emerged in three hospitals North of Berlin. This strain, Barnim epidemic MRSA, was isolated in 15 hospitals in Northern Germany in 1997 and 29 hospitals throughout Germany in 1998. Isolates of this clone are non-typeable by phages, its resistance phenotype is PEN, OXA, ERY, CLI, CIP (genotype: mecA, ermC, mutations in grlA and gyrA). The Sma I macrorestriction pattern corresponds to particular phage group II strains which is confirmed by the 16S-23S rRNA gene spacer pattern. Isolates of this clone differ by less than three Sma I macrorestriction fragments from isolates of the EMRSA15 clone from the United Kingdom, the most common epidemic MRSA isolates in the United Kingdom in recent years. Both epidemic strains produce enterotoxin C and possess the sec determinant for this toxin, the configuration of the mec regulon is mecI-, mecRB+, mecRC+. Both share the same Alu I pattern of PCR amplimers of the 3' end region of the coagulase gene. EMRSA 15 and Barnim EMRSA share a common multilocus sequence type indicating a recent, shared evolutionary origin.
Bacterial Typing Techniques↗
Subtyping of MRSA isolates belonging to a widely disseminated clonal group by polymorphism of the dru sequences in mec-associated DNA.
During the past 7 years the "Berlin epidemic MRSA" has spread throughout whole Germany. SmaI macrorestriction patterns of this clonal group are rather stable as are the length polymorphisms at the 3' end of the coagulase gene and the x-region of spa. However, the dru region (direct repeat units) of mec-associated DNA exhibits a length polymorphism due to deletion of one or more direct repeat units. Five different subclones could be discriminated by dru region length polymorphism. Location of deletions and of a few point mutations allow a delineation of these subclones.
Base Sequence↗
Methicillin-resistant, quinupristin-dalfopristin-resistant Staphylococcus aureus with reduced sensitivity to glycopeptides.
Of 3,052 Staphylococcus aureus strains collected by the European SENTRY surveillance study, 35 were found to be nonsusceptible to quinupristin-dalfopristin (MIC of > or =2 mg/liter). These isolates originated from four hospitals in France and one in Spain. In isolates from two Parisian hospitals exhibiting the same SmaI macrorestriction pattern, streptogramin resistance was based on vatA and vgbA. One isolate from a hospital in Lyon and 22 from a hospital in Lille were of the vatB vgaB streptogramin A resistance genotype and possessed ermA and/or ermC. As deduced from the loss of either streptogramin A or streptogramin B resistance determinants in particular isolates, resistance to quinupristin-dalfopristin requires mechanisms conferring resistance to both compounds. The SmaI macrorestriction patterns of strains from hospitals in Lille and Lyon were different; however, similarity analysis suggested a relatedness of 20 methicillin-resistant S. aureus strains from the Lille hospital, a finding confirmed by PCR typing based on three different genomic polymorphisms. These groups of isolates were found to be hetero-glycopeptide-intermediate susceptible S. aureus. Information about the failure of glycopeptide chemotherapy has not been available.
Anti-Bacterial Agents↗
Ecological impact of antibiotic use in animals on different complex microflora: environment.
Different means of interaction between microecological systems in different animal hosts (including humans) and the environment may occur during the transfer of resistant bacteria and their resistance genes. Spread of resistance takes place in different ways with respect to clonal spread of resistance strains by the spread of wide host range plasmids and translocatable elements. Commensals in ecosystems have a special significance and a pronounced capacity for acquisition and transfer of resistance genes as with Enterococcus faecium and Escherichia coli in the gut flora or Pseudomonas spp. in aquatic environments. The route of transmission from animals to humans by meat products is well established. Other routes via water and food plants (vegetables) have been investigated less, although resistance genes transfer in aquatic environments as evidenced from sequence comparison of such genes (e.g. tetR, floR in Salmonella typhimurium DT104). Whether this is due to rare but important transfer events or whether there is a more frequent exchange in aquatic or terrestrial environments needs further elucidation.
Animal Feed↗
In vitro activity of gatifloxacin compared with gemifloxacin, moxifloxacin, trovafloxacin, ciprofloxacin and ofloxacin against uropathogens cultured from patients with complicated urinary tract infections.
Minimum inhibitory concentrations (MICs) of gatifloxacin were compared with those of gemifloxacin, moxifloxacin, trovafloxacin, ciprofloxacin and ofloxacin using an agar dilution method for 400 uropathogens cultured from the urine of urological patients with complicated and/or hospital-acquired urinary tract infections (UTI). The collection of strains was made up of Enterobacteriaceae (34.5%), enterococci (31.5%), staphylococci (21.2%) and non-fermenting bacteria (12.8%). The antibacterial activity of the three newer fluoroquinolones, gatifloxacin, gemifloxacin, and moxifloxacin, were similar, but showed some drug specific differences. Gemifloxacin was most active against Escherichia coli, but less so against Proteus mirabilis. In this series all isolates of E. coli were inhibited at a MIC of 0.25 mg/l gatifloxacin and moxifloxacin and by 0.125 mg/l gemifloxacin. The MIC distribution of all fluoroquinolones showed a bimodal distribution for staphylococci, enterococci and Pseudomonas aeruginosa. The two modes for P. aeruginosa were 1 and 64 mg/l for gemifloxacin and moxifloxacin and 0.5 and 64 mg/l for gatifloxacin. For staphylococci the two modes were 0.125 and 2 mg/l for gatifloxacin, 0.03 and 4 mg/l for gemifloxacin, and 0.03 and 2 mg/l for moxifloxacin; for enterococci, 0.25 and 16 mg/l for gatifloxacin, 0.06 and 2 mg/l for gemifloxacin, and 0.25 and 8 mg/l for moxifloxacin. Compared with trovafloxacin the MICs were similar, but the newer fluoroquinolones were more active than ciprofloxacin and ofloxacin against Gram-positive bacteria. Of the newer fluoroquinolones gatifloxacin had the highest rate of renal excretion and could be considered a promising alternative fluoroquinolone agent for the treatment of UTI.
Anti-Infective Agents↗
Selective pressure by antibiotic use in livestock.
Selective pressure exerted by the use of antibiotics as growth promoters in food animals appears to have created large reservoirs of transferable antibiotic resistance in these ecosystems. This first became evident for oxytetracycline and later for the streptothricin antibiotic nurseothricin, for which a transfer of relevant resistance determinants (sat genes) to bacterial pathogens of humans was demonstrated. With the emergence of glycopeptide resistance in Enterococcus faecium outside hospitals, a large reservoir of transferable resistance (vanA gene cluster) was identified in animal husbandry due to the use of avoparcin as feed additive. The spread of resistance, which reaches the human enterococcal flora via meat products, is probably due to the dissemination of the vanA gene cluster integrated into different conjugative plasmids among a variety of different strains. Streptogramin resistance associated with the resistance genes vatA and vatG has been found in E. faecium of animal and of clinical origin. Because virginiamycin has been used as growth promoter in animals but streptogramins have been used infrequently in human medicine, this again suggests an animal origin of resistance. Since the use of avoparcin ended, a decline in the rates of glycopeptide-resistant E. faecium (GREF) from animals and humans in the community has been recorded. This supports the ban of antibacterial growth promoters that might interfere with human chemotherapy that has been introduced in European Union countries.
Animals↗
Linkage of determinants for streptogramin A, macrolide-lincosamide-streptogramin B, and chloramphenicol resistance on a conjugative plasmid in Enterococcus faecium and dissemination of this cluster among streptogramin-resistant enterococci.
A new streptogramin A resistance gene, satG (= vatE), has been recently identified in Enterococcus faecium UW1965 (Werner and Witte 1999. Antimicrob. Agents Chemother. 43: 1813-1814). Further sequence analysis of this plasmid revealed that vatE is in a cluster together with other resistance genes. The identified ORFs were nearly identical with the already known genes ermB and cat. The ermB fragment exhibited more than 99% identity with a resistance region from the streptococcal plasmid pIP501, whereas the cat fragment also contained a truncated rep gene homologue with more than 99% identity to sequences in small staphylococcal plasmids. The cat-rep and the ermB-vatE segments were linked by an IS1216V insertion sequence widely distributed among enterococci. PCR analysis of additional 76 streptogramin-resistant isolates possessing vatE and ermB revealed a linkage of both genes in 45 isolates (59%); 15 of them with a gene arrangement, cat-repU-IS1216V-ermB-vatE, identical to the reference strain UW1965. An identical linkage of IS1216V-ermB-vatE was found among isolates from poultry manure, poultry meat, stool samples of humans, and hospital patients indicating a possible spread of the resistance gene cluster via the food chain to humans.
Anti-Bacterial Agents↗
Clonal dissemination of epidemic methicillin-resistant Staphylococcus aureus in Belgium and neighboring countries.
OBJECTIVES: To determine the diversity of pulsed-field gel electrophoresis (PFGE) types among epidemic strains of methicillin-resistant Staphylococcus aureus (MRSA) recovered in Belgium, France, Germany and The Netherlands over the period 1981-94. METHODS: MRSA strains collected in a multicenter survey in Belgium (n = 171) and from reference laboratories in neighboring countries (n = 102) were characterized by PFGE analysis using the SmaI enzyme. RESULTS: In total, 32 PFGE types were found. Epidemic PFGE type 1, first recognized in 1984, accounted for 82% of Belgian strains (87% of hospitals) and 51% of European MRSA strains. Four other internationally epidemic PFGE types (types 8, 10, 11 and 12) were less widely disseminated and more recently detected (1991-94), each recovered from two or three countries. International spread of two PFGE types was linked to transfer of colonized patients to Dutch hospitals from another country where this type was frequently recovered. CONCLUSIONS: Genotypic analysis indicated widespread distribution of several outbreak-associated MRSA strains over large European regions, which was in some instances related to interhospital patient transfer. These findings underscore the need for standardized international surveillance and control of MRSA transmission between healthcare institutions across Europe.
Bacteriophage Typing↗
In vitro activity of linezolid against staphylococci.
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Acetamides↗
Nosocomial cross transmission as a primary cause of vancomycin-resistant enterococci in Austria.
Stool specimens from 226 patients from intensive care units (N=69), general wards (N=112), and outpatient-clinics (N=45) at the Innsbruck University Hospital and from 433 healthy volunteers were inoculated on to Enterococcosel Agar supplemented with 5 microg/mL vancomycin and 4 microg/mL cefodizime. Faecal specimens from 105 dairy cows, 171 pigs and 47 egg-laying hens were processed the same way. Thirteen of 226 patients (5.8%) harboured 14 vancomycin-resistant enterococci (VRE) of the vanA genotype; 12 E. faecium (from 11 patients) and two E. faecalis (ICU patients: 5.8%, general ward patients: 5.4%, outpatients: 6.7%). None of the faecal specimens from healthy volunteers or animals yielded VRE. Nine of the 13 patients harbouring VRE had received antibiotic therapy during the previous four weeks (broad-spectrum cephalosporins: six patients; i.v. vancomycin: five patients). Of the 14 VRE (vanA type) isolates six strains were indistinguishable by PFGE using Sma I as restriction endonuclease, six strains formed three pairs, and only two single isolates showed unique patterns. The results of our study supports the view that nosocomial cross transmission is currently the main cause of colonization and infection with VRE in Austria.
Animals↗
Quinupristin/dalfopristin-resistant enterococci of the satA (vatD) and satG (vatE) genotypes from different ecological origins in Germany.
The semisynthetic streptogramin combination quinupristin/dalfopristin (Synercid) is a promising alternative for treatment of infections due to multiply resistant gram-positive bacteria including vancomycin-resistant Enterococcus faecium. Resistance is mediated by acetyltransferases SatA (VatD) or SatG (VatE). Recent papers have indicated a possible link between the use of the streptogramin virginiamycin S/M as a feed additive in commercial animal husbandry and a selection of quinupristin/dalfopristin-resistant E. faecium (QDRE). We screened manure samples from two different turkey farms and from six different pig farms (using virginiamycin), samples from a sewage water treatment plant, 24 broiler carcasses, 10 pork samples, and 200 stool samples of nonhospitalized humans for QDRE. Our strain culture collection of hospital E. faecium isolates from the last 2 years was also reviewed for QDRE. All manure and sewage samples were positive for QDRE, as well as 11 from broiler carcasses (46%), 1 from pork (10%), and 28 from human stool specimens (14%). Thirty-six hospital isolates of E. faecium exhibited resistance to quinupristin/dalfopristin. In 141 QDRE of different origin satA (vatD) and satG (vatE) genes were detected (seven isolates from humans with an unknown resistance mechanism). Streptogramin resistance determinants were tansferable in filtermating experiments for 5 of 10 satA (vatD) and 9 of 22 satG (vatE) isolates. Different EcoRI patterns of satG (vatE) plasmids and corresponding hybridizations of the satG (vatE) gene indicated nonhomologous resistance plasmids in isolates of different origin. The results of this study indicate a common gene pool for streptogramin resistance in E. faecium of different ecological origin. A selection of QDRE using the streptogramin virginiamycin S/M as a feed additive and a spread of the resistance via the food chain to humans is probable.
Acetyltransferases↗
Impact of flavophospholipol and vancomycin on conjugational transfer of vancomycin resistance plasmids.
The influence of vancomycin and flavophospholipol (FPL) on the transfer rate of conjugative plasmids harboring the vancomycin resistance operon vanA was determined in several clinical and animal isolates of Enterococcus faecium. FPL significantly inhibited the frequency of transfer of conjugative VanA plasmids up to 70-fold. Vancomycin had no significant effect on the transfer rate of VanA plasmids.
Anti-Bacterial Agents↗
Effect of subinhibitory antibiotic concentrations on polysaccharide intercellular adhesin expression in biofilm-forming Staphylococcus epidermidis.
Biofilm production is an important step in the pathogenesis of Staphylococcus epidermidis polymer-associated infections and depends on the expression of the icaADBC operon leading to the synthesis of a polysaccharide intercellular adhesin. A chromosomally encoded reporter gene fusion between the ica promoter and the beta-galactosidase gene lacZ from Escherichia coli was constructed and used to investigate the influence of both environmental factors and subinhibitory concentrations of different antibiotics on ica expression in S. epidermidis. It was shown that S. epidermidis biofilm formation is induced by external stress (i.e., high temperature and osmolarity). Subinhibitory concentrations of tetracycline and the semisynthetic streptogramin antibiotic quinupristin-dalfopristin were found to enhance ica expression 9- to 11-fold, whereas penicillin, oxacillin, chloramphenicol, clindamycin, gentamicin, ofloxacin, vancomycin, and teicoplanin had no effect on ica expression. A weak (i.e., 2.5-fold) induction of ica expression was observed for subinhibitory concentrations of erythromycin. The results were confirmed by Northern blot analyses of ica transcription and quantitative analyses of biofilm formation in a colorimetric assay.
Adhesins, Bacterial↗
Multicenter evaluation of epidemiological typing of methicillin-resistant Staphylococcus aureus strains by repetitive-element PCR analysis. The European Study Group on Epidemiological Markers of the ESCMID.
Rapid and efficient epidemiologic typing systems would be useful to monitor transmission of methicillin-resistant Staphylococcus aureus (MRSA) at both local and interregional levels. To evaluate the intralaboratory performance and interlaboratory reproducibility of three recently developed repeat-element PCR (rep-PCR) methods for the typing of MRSA, 50 MRSA strains characterized by pulsed-field gel electrophoresis (PFGE) (SmaI) analysis and epidemiological data were blindly typed by inter-IS256, 16S-23S ribosomal DNA (rDNA), and MP3 PCR in 12 laboratories in eight countries using standard reagents and protocols. Performance of typing was defined by reproducibility (R), discriminatory power (D), and agreement with PFGE analysis. Interlaboratory reproducibility of pattern and type classification was assessed visually and using gel analysis software. Each typing method showed a different performance level in each center. In the center performing best with each method, inter-IS256 PCR typing achieved R = 100% and D = 100%; 16S-23S rDNA PCR, R = 100% and D = 82%; and MP3 PCR, R = 80% and D = 83%. Concordance between rep-PCR type and PFGE type ranged by center: 70 to 90% for inter-IS256 PCR, 44 to 57% for 16S-23S rDNA PCR, and 53 to 54% for MP3 PCR analysis. In conclusion, the performance of inter-IS256 PCR typing was similar to that of PFGE analysis in some but not all centers, whereas other rep-PCR protocols showed lower discrimination and intralaboratory reproducibility. None of these assays, however, was sufficiently reproducible for interlaboratory exchange of data.
Bacterial Typing Techniques↗
Antimicrobial therapy in a historical perspective.
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Animals↗