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PubMed2004

Characterization of high-level aminoglycoside-resistant enterococci in Kuwait hospitals.

This study investigated the distribution of genes for aminoglycoside-modifying enzymes (AME) and the genetic relatedness of high-level aminoglycoside-resistant enterococci isolated in Kuwait hospitals. A total of 117 enterococci, consisting of 109 Enterococcus faecalis, seven Enterococcus faecium, and one Enterococcus casseliflavus were studied. The MICs of gentamicin, kanamycin, amikacin, tobramycin, and streptomycin were determined by agar dilution and the genes encoding the AAC(6')- APH(2"), ANT(4'), APH(3'), APH (2")-Ib, APH (2")-Ic, APH (2")-Id, and ANT(6) enzymes were amplified by PCR. They were typed by pulsed-field gel electrophoresis (PFGE). Filter mating was used to transfer gentamicin resistance determinants. They were all resistant to kanamycin (MIC 2000 mg/L). Fifty-five isolates were resistant to gentamicin (MIC 500 mg/L), 72 were resistant to tobramycin (MIC 64 mg/L), 115 were resistant to amikacin (MIC 64 mg/L), and 97 were resistant to streptomycin (MIC 1000 mg/L). The aac(6')-Ie-aph(2")-Ia was detected in all isolates with gentamicin MIC 500 mg/L and in 15 isolates with gentamicin MIC 256 mg/L. The aph(3')-IIIa gene was detected in 101 isolates, whereas the ant(6')-Ia gene was detected in 85 of the 97 streptomycin-resistant isolates with MIC 1000 mg/L. The aac(6')-Ii gene was detected only in the seven E. faecium isolates. None of them contained ant(4')-Ia, aph(2")-Ib, aph(2")-Ic and aph(2")-Id. PFGE revealed heterogeneous patterns with no dominant clone. The results demonstrated that AME are common in aminoglycoside-resistant enterococci isolated in Kuwait. However, the absence of a dominant clone suggests that they acquired high-level aminoglycoside independently.

Aminoglycosides↗

PubMed1997

[Antibiotic resistance of enterococci in Germany].

BACKGROUND: The resistance of enterococci against various antimicrobial substances including vancomycin has increased markedly. Since 1989 in the USA in particular high resistance rates against vancomycin have been observed but very few surveillance have been published in Europe. Therefore, we conducted a multicenter study in Germany to obtain information about the incidence and distribution of vancomycin and/or high-level aminoglycoside-resistant enterococci. METHODS: A total of 2046 enterococcal isolates were identified and susceptibility-testing was performed according to international guidelines. RESULTS: A total number of 90.5% of the enterococcal isolates were identified as Enterococcus faecalis and 7.8% was Enterococcus faecium. Resistance against ampicillin was detected in 56.6% of the Enterococcus faecium isolates, however, in only one Enterococcus faecalis isolate. High-level resistance against gentamycin or streptomycin was observed in 7.3% and 24.8% of the isolates, respectively. Twelve isolates showed resistance against vancomycin, however, cross resistance with teicoplanin was found in only two isolates. CONCLUSION: The rate of resistance of enterococci in Germany is still considerably lower than in the United States. Previous vancomycin therapy has been implemented as a risk factor for colonization or infection with vancomycin-resistant enterococci. Continued vigilance, decreased use of vancomycin and strict enforcement of infection control measures are appropriate measures to control the growing problem of resistant enterococci.

Ampicillin Resistance↗

PubMed1993

[Bacterial reducing qualities of copper-containing and non-copper-containing materials. I. Contamination and sedimentation in humid and dry conditions].

In this examination the bactericide qualities of different materials were tested. Particularly the effect of humidity was examined. 3 materials containing copper ("copper", "brass" and "brass sheet") and 2 materials not containing copper ("polyamide B" and "high-grade steel") were tested. The surfaces of the 5 types of material were contaminated with a suspension of 2 different bacteria species (Staphylococcus aureus and Micrococcus luteus). After defined exposure times the survival rate of the microorganisms on the surfaces was determined by the standardized method of the "Guidelines of the German Society of Hygiene and Microbiology". Additionally the sedimentation of airborne microorganisms on the materials was tested by determining the number of colony-forming-units after defined exposure times. In further examinations the materials were contaminated by hands, which were dipped into a suspension of different microorganisms (Micrococcus luteus, Staphylococcus aureus, Enterococcus faecium, Escherichia coli, Enterobacter cloacae and Pseudomonas aeruginosa). The following ways of contaminating the test materials were chosen: single contamination with wet hands, repeated contamination with wet and dry hands. After defined exposure times the survival rate of the microorganisms on the surfaces was determined. The results show, a bactericide quality of copper depends on the percent of copper-content of the tested materials, exposure time, humidity, frequency of contamination and bacteria species. Humidity and only single contamination cause a reduction of bacteria. Reduction of gram-negative bacteria is more easily than reduction of gram-positive bacteria. Enterococcus faecium shows the highest, Pseudomonas aeruginosa the lowest reduction rate of bacteria in the following sequence: Enterococcus faecium, Escherichia coli, Enterobacter cloacae, Micrococcus luteus, Staphylococcus aureus and Pseudomonas aeruginosa.

Air Microbiology↗

PubMed1987

Comparative survival of antibiotic-resistant and -sensitive fecal indicator bacteria in estuarine water.

The survival of antibiotic-resistant and -sensitive strains of Escherichia coli, Enterococcus faecalis, Enterococcus faecium, Streptococcus equinus, and two environmental isolates, AP17 and AQ62, was examined in estuarine water. Each strain was rendered resistant to a combination of two antibiotics by serial passage in increasing concentrations of antibiotics. Cultures were incubated in filter-sterilized estuarine water for up to 7 days. Recovery was assessed by examining colony-forming ability on media with and without antibiotics. None of the antibiotic-resistant forms survived longer than its antibiotic-sensitive counterpart in estuarine water. Three of the resistant strains died off more rapidly than the antibiotic-sensitive wild type. Survival of the test bacteria in estuarine water was as follows: sensitive and resistant AQ62, resistant Escherichia coli less than sensitive Escherichia coli less than resistant AP17 less than resistant Enterococcus faecium less than sensitive AP17, sensitive and resistant S. equinus less than sensitive and resistant Enterococcus faecalis, sensitive Enterococcus faecium. The results supported the suggestion that fecal entercocci may serve as better indicators of fecal pollution than Escherichia coli in marine ecosystems. Moreover, the results indicated that the use of antibiotic-resistant mutants to follow the fate of bacteria in the environment is inappropriate without adequate studies to ensure that resistant and wild-type strains react similarly to environmental stressors.

Anti-Bacterial Agents↗

PubMed1995

Resistance to aminoglycosides and other antibiotics among clinical isolates of Enterococcus spp.

We conducted a study on 81 clinical isolates of enterococci (65 Enterococcus faecalis and 16 Enterococcus faecium) collected consecutively over a one year period at our University Hospital. Of them, 10 (15%) Enterococcus faecalis and 6 (38%) Enterococcus faecium showed high level resistance to aminoglycosides, were all acquired in surgical units and in five cases they were responsible for invasive infections. Ampicillin and imipenem were active only against Enterococcus faecalis. Vancomycin and teicoplanin were bacteriostatic; however, teicoplanin MICs were lower and in 45% of cases its MBC values were within clinically achievable serum concentrations. Ciprofloxacin and cotrimoxazole were active in vitro.

Aminoglycosides↗

PubMed1998

Clonal diversity of vancomycin-resistant enterococci from an outbreak in a tertiary care university hospital.

BACKGROUND: Enterococci have become important nosocomial pathogens and now account for approximately 12% of nosocomial infections. Enterococci can be transferred from patient to patient and from health care personnel to patient. We investigated the clonal diversity of vancomycinresistant enterococci (VRE) causing an outbreak of infections and attempted to determine the patterns of spread of these bacteria in a university hospital. METHODS: Ribotyping was used to examine the clonal diversity of 50 VRE isolates, including 23 from wounds, 14 from urine, 8 from blood, 3 from the rectum, 1 from drainage, and 1 from the cornea. RESULTS: Nine patients were infected with Enterococcus faecalis, 10 with Enterococcus faecium, 3 with both E faecalis and E faecium, and 1 with Enterococcus avium. The results suggest that the sources of the VRE infections included endogenous strains and strains acquired by transmission from attending staff or from the environment. Three patients were infected by both nosocomial and endogenous strains. CONCLUSIONS: These data suggest that the collection and analysis of several isolates from repeated specimens is necessary to obtain a fuller understanding of the epidemiology and population structure of antibiotic-resistant enterococci.

Anti-Bacterial Agents↗

PubMed1995

Epidemiologic analysis of glycopeptide-resistant Enterococcus strains in neutropenic patients receiving prolonged vancomycin administration.

Vancomycin-resistant enterococci have been isolated with increasing frequency since 1988. Thus far, most of these resistant enterococci have belonged to the Enterococcus faecium species, and epidemiological studies have shown a wide diversity among interhospital and intrahospital isolates. This report presents an epidemiologic investigation of 25 vancomycin-resistant Enterococcus strains--24 Enterococcus faecium and one Enterococcus gallinarum--isolated from the stools or blood of adult patients receiving intravenous vancomycin prophylaxis during neutropenia and hospitalized in a single hematologic unit. Macrorestriction patterns of total DNA and of ribosomal DNA regions were used to analyze the strains. Strains produced different total DNA restriction fragment length polymorphism patterns after SmaI digestion. Ribotyping was less discriminative than pulsed-field gel electrophoresis. The results confirmed the genetic unrelatedness of the strains. Prolonged vancomycin administration, commonly used in hematologic units, could be involved in the selection of endogenous resistant enterococcal strains.

Anti-Bacterial Agents↗

PubMed2000

Prevalence and determinants of fecal colonization with vancomycin-resistant Enterococcus in hospitalized patients in The Netherlands.

OBJECTIVE: To determine the prevalence and determinants of fecal carriage of vancomycin-resistant enterococci (VRE) in intensive care unit (ICU), hematology-oncology, and hemodialysis patients in The Netherlands. DESIGN: Descriptive, multicenter study, with yearly 1-week point-prevalence assessments between 1995 and 1998. POPULATION: All patients hospitalized on the testing days in ICUs and hematology-oncology wards in nine hospitals in The Netherlands were included. METHODS: Rectal swabs obtained from 1,112 patients were screened for enterococci in a selective broth and subcultured on selective media with and without 6 mg/L vancomycin. Resistance genotypes were determined by polymerase chain reaction. Further characterization of VRE strains was done by pulsed-field gel electrophoresis (PFGE). We studied possible determinants of VRE colonization with a logistic regression analysis model. Determinants analyzed included gender, age, and log-transformed length of prior hospital stay. RESULTS: The results showed that 614 (55%) of 1,112 patients were colonized with vancomycin-sensitive enterococci, and 15 (1.4%) of 1,112 carried VRE. No increase in VRE colonization was observed from 1995 to 1998. Eleven strains were identified as Enterococcus faecium and four as Enterococcus faecalis. All E faecium and one E faecalis carried the vanA gene; the other E faecalis strains harbored the vanB gene. PFGE revealed that three vanB VRE isolated from patients hospitalized in one single ICU were related, suggesting nosocomial transmission. Though higher age seemed associated with VRE colonization, exclusion of patients with the nosocomial strain from the regression analysis decreased this relation to nonsignificant. Duration of hospital stay was not associated with VRE colonization. CONCLUSION: VRE colonization in Dutch hospitals is an infrequent phenomenon. Although nosocomial spread occurs, most observed cases were unrelated, which suggests the possibility of VRE acquisition from outside the hospital. Prolonged hospital stay, age, and gender proved unrelated to VRE colonization.

Adolescent↗

PubMedDate not supplied

Colonization with vancomycin-resistant enterococci (VRE) in intensive care unit patients in Cordoba City, Argentina.

The purpose of this study was to determine the prevalence of colonization with vancomycin-resistant enterococci (VRE) among intensive care unit (ICU) patients in a hospital in Córdoba, Argentina. We collected 235 rectal swab specimens from 147 ICU patients. Resistance to vancomycin was screened with the disk diffusion method, and MICs were determined with the E-test method. Vancomycin-resistant genotypes were determined by PCR. The VRE strains were isolated from 18/147 patients (12.2%). The isolates were identified as Enterococcus faecium (94.4%), and Enterococcus gallinarum (5.6%). PCR showed that the E. faecium strains carried the vanA gene, and the E. gallinarum strain carried the vanC1 gene. Our study indicated that at least 12.2% of ICU patients were VRE carriers.

Argentina↗

PubMed2006

Use of the Phoenix automated system for identification of Streptococcus and Enterococcus spp.

The Phoenix system (Becton Dickinson Diagnostic Systems, Sparks, MD) was evaluated for identification (ID) to the species level of streptococci and enterococci. Two hundred clinical isolates were investigated: beta-hemolytic streptococci (n = 50), Streptococcus pneumoniae organisms (n = 46), viridans group streptococci (n = 31), Enterococcus faecium (n = 36), Enterococcus faecalis (n = 25), and other catalase-negative cocci (n = 12). The API system (bioMérieux, Marcy l'Etoile, France) was used as a comparator. Molecular methods (sequencing of 16S rRNA and zwf and gki genes and ddl gene amplification) were used to investigate discordant results. Upon resolution of discrepancies, correct species ID was achieved by the Phoenix system for 121/129 (93.8%) streptococci and 63/70 (90.0%) enterococci. Excellent results were obtained for S. pneumoniae (45/45) and beta-hemolytic streptococci (49/50). With regard to viridans streptococci, the accuracy of the Phoenix system was 83.9%. Among the latter organisms, the best performance was obtained with isolates of the Streptococcus sanguinis group and Streptococcus anginosus group; problems were instead encountered with the Streptococcus mitis group. Four E. faecium and three E. faecalis isolates were misidentified as Enterococcus casseliflavus/Enterococcus gallinarum or Enterococcus durans. Thus, these isolates were identified only at the genus level. Compared with commercially available systems, the Phoenix system appears a reliable diagnostic tool for identifying clinically relevant streptococci and enterococci. The SMIC/ID-2 panel proved particularly effective for beta-hemolytic streptococci and pneumococci.

Automation↗

PubMed1990

Evaluation of MicroScan for identification of Enterococcus species.

Emerging drug resistance of the enterococci necessitates differentiation from group D streptococci and accurate species identification. MicroScan (Baxter Healthcare Corp., West Sacramento, Calif.) has recently developed a microdilution system for identification and antibiotic susceptibility testing of gram-positive cocci. To evaluate the ability of this system to identify Enterococcus species, 100 isolate identified as enterococci by MicroScan were tested by conventional media and 60 isolates of streptococci were tested by MicroScan. Incubation times for conventional and MicroScan methods were 96 and 18 to 24 h, respectively. For 94 strains of enterococci (77 Enterococcus faecalis, 14 Enterococcus faecium, and 3 Enterococcus durans), identification by conventional media and MicroScan agreed. Of the remaining six isolates, four were identified as E. faecalis and two were identified as E. durans by MicroScan, whereas by conventional media the four E. faecalis isolates were identified as Enterococcus solitarius and the two E. durans isolates were identified as Enterococcus hirae. None of the 60 streptococci were identified as enterococci. MicroScan is a reliable method for identification of the commonly encountered enterococcal species E. faecalis and E. faecium; however, modifications of the system are necessary for identification of other Enterococcus species.

Autoanalysis↗

PubMed2006

Outbreak of vancomycin-resistant Enterococcus spp. in an Italian general intensive care unit.

Following the identification of two clinical isolates of vancomycin-resistant enterococci (VRE) from intensive care unit (ICU) patients, a surveillance programme detected that six of eight ICU patients were colonised by VRE. Standard epidemic control measures were instituted in the ICU. During a 16-month period, 13 (2.5%) of 509 ICU patients had VRE-positive swabs upon admission, and 43 (8.7%) of 496 VRE-negative patients were colonised by VRE in the ICU. Patients who acquired VRE in the ICU had a longer ICU stay (p < 0.0001). No other statistically significant differences were demonstrated. Two patients had documented infection (infection/colonisation index, 3.6%; overall VRE infection frequency, 0.4%), but both recovered and were discharged. VRE colonisation did not increase the mortality rate. Automated ribotyping identified three clusters containing, respectively, the first 52 Enterococcus faecium isolates, two Enterococcus faecalis isolates, and two further isolates of E. faecium. Multilocus sequence typing demonstrated that two E. faecium isolates representative of the two ribotypes belonged to sequence types 78 and 18, and that these two isolates belonged to the epidemic lineage C1, which includes isolates with a wide circulation in northern Italy. The outbreak was controlled by continuous implementation of the infection control programme, and by the opening of a new unit with an improved structural design and hand-washing facilities.

Adult↗

PubMed1997

In vitro activity and spectrum of LY333328, a novel glycopeptide derivative.

Reference methods were used to determine the potency of LY333328, a semisynthetic glycopeptide derivative with a key N-alkylation substitution, against 833 strains (393 gram-positive strains and representative gram-negative bacilli) with various defined resistance mechanisms. The MICs at which 90% of the isolates are inhibited (MIC90S) (in micrograms per milliliter) of LY333328 and the percentages of strains at < or = 8 micrograms/ml were as follows: for oxacillin-susceptible Staphylococcus aureus, 2 and 100%, and for oxacillin-resistant Staphylococcus aureus, 4 and 100%; for oxacillin-susceptible Staphylococcus epidermis, 4 and 100%, and for oxacillin-resistant Staphylococcus aureus, 8 and 96%; for Streptococcus serogroups A, B, C, and G, 0.25 to 1 and 100%; for Streptococcus pneumoniae < or = 0.015 to 0.06 and 100%; for Enterococcus faecalis, 2 and 100%; and for vancomycin-susceptible Enterococcus faecium, 0.25 and 100%, and for vancomycin-resistant Enterococcus faecium, 4 and 100%. LY333328 was not active (MIC50, > or = 16 micrograms/ml) against more than 400 representative strains of Enterobacteriaceae, pseudomonads, Acinetobacter spp., Stenotrophomonas maltophilia, Haemophilus influenzae, Moraxella catarrhalis, pathogenic Neisseria spp., and anaerobic gram-negative bacilli. Gram-positive anaerobes were LY333328 susceptible (MICs, < or = 2 micrograms/ml). Test methods and conditions may have affected MICs of LY333328, with most (species variation) agar dilution MICs being greater than the broth microdilution MICs.

Anti-Bacterial Agents↗

PubMed2006

Influence of pre-, pro-, and synbiotics on the intestinal availability of different B-vitamins.

This study was conducted with 16 male growing pigs (eight pigs with an end-to-end ileo-rectal anastomosis, eight intact pigs) to investigate in metabolic trials the influence of different pre-, pro-, and synbiotics on the precaecal and faecal digestibility of thiamin, riboflavin, pantothenic acid and biotin. A basic experimental diet was supplemented with either pre-, pro-, or synbiotic additives as follows: lactulose (2%), inulin (2%), mannanoligosaccharides (0.3%), Enterococcus faecium DSM 10663 (8 x 10(9) cfu/kg), Enterococcusfaecium DSM 7134 (5 x 10(8) cfu/kg), inulin + Enterococcusfaecium DSM 10663, mannanoligosaccharides + Enterococcus faecium DSM 7134. The precaecal and faecal digestibilities of the investigated B-vitamins were not affected significantly by the administered pre-, pro-, and synbiotics independent of the application period. A higher faecal vitamin excretion vs. the precaecal indicated that thiamin and biotin were synthesized in the colon. On the contrary, for riboflavin and pantothenic acid a higher precaecal vitamin flow compared to the faecal excretion was detected indicating to a certain extent an absorption in the colon.

Anastomosis, Surgical↗

PubMed1996

Unorthodox antibiotic combinations including ciprofloxacin against high-level gentamicin resistant enterococci.

Development of high-level gentamicin resistance among enterococci represents a serious therapeutic problem as it precludes synergy between aminoglycosides and cell-wall active agents. As part of a search for active antibiotic combinations against enterococci with high-level gentamicin resistance, we tested by the time kill curve method the efficacy of ciprofloxacin combined with ampicillin, trimethoprim-sulphamethoxazole, vancomycin or teicoplanin against ten isolates of Enterococcus faecium, three of Enterococcus casseliflavus and 13 of Enterococcus faecalis that exhibited a MIC of gentamicin > or = 2000 mg/L. Most of the E. faecium were also resistant to ampicillin and to ciprofloxacin. The combination of ciprofloxacin with ampicillin was bactericidal against five of seven E. faecium strains that exhibited a ciprofloxacin MIC < or = 4 mg/L, but was inactive against the three E. faecium that were highly resistant to ciprofloxacin. This combination was also bactericidal against the E. casseliflavus and all the E. faecalis strains. The combination of ciprofloxacin with trimethoprim-sulphamethoxazole was bactericidal against five of the seven E. faecium and seven of the nine E. faecalis strains with a ciprofloxacin MIC < or = 4 mg/L. No bactericidal activity of this combination was seen against the enterococci that were highly resistant to either ciprofloxacin or to trimethoprim-sulphamethoxazole. The combination of ciprofloxacin with glycopeptides was inactive against E. faecium and E. casseliflavus and against E. faecalis, it was either ineffective or antagonistic; in only one case it was bactericidal. Five strains of E. faecium were resistant to all antibiotic combinations tested.

Ampicillin↗

PubMed1998

European Glycopeptide Susceptibility Survey of gram-positive bacteria for 1995. European Glycopeptide Resistance Survey Study Group.

In the European Glycopeptide Susceptibility Survey 7078 Gram-positive isolates collected in 1995 from 70 centers in 9 countries of Western Europe were examined, using a standardized, quantitative susceptibility testing method. Of the 7078 isolates, 6824 (96.4%) were tested by the national coordinating centers. Teicoplanin (mode MIC 0.5 microgram/mL) was generally twice as active as vancomycin (mode MIC 1 microgram/mL) against Staphylococcus aureus (n = 2852). All isolates were susceptible to vancomycin (MIC < or = 4 micrograms/mL) and all but four to teicoplanin (MIC < or = 8 micrograms/mL); these four isolates were of intermediate susceptibility (MIC 16 micrograms/mL). With coagulase-negative staphylococci (n = 1444), the distribution of MIC of teicoplanin was wider than for vancomycin. Two and two-tenths percent of coagulase-negative staphylococci excluding Staphylococcus haemolyticus required 16 micrograms/mL teicoplanin for inhibition (intermediate) and 0.4% > or = 32 micrograms/mL (resistant). Among isolates of S. haemolyticus, 4.4% were of intermediate susceptibility (MIC 16 micrograms/mL) and 3.3% were resistant (MIC > or = 32 micrograms/mL) to teicoplanin. However, this species represented only 6.3% of the isolates of coagulase-negative Staphylococcus spp. Generally, teicoplanin (mode MIC < or = 0.12 microgram/mL) was four to eight times more active than vancomycin (mode MIC < or = 0.5 microgram/mL) against the 770 streptococcal isolates. Glycopeptide-susceptible Enterococcus spp. (n = 1695) were generally four times more susceptible to teicoplanin (mode MIC 0.25 microgram/mL) than to vancomycin (mode MIC 1 microgram/mL). Combined vancomycin and teicoplanin (VanA phenotype) resistance was observed more frequently (9.3%) in isolates of Enterococcus faecium than in Enterococcus faecalis (0.8%). Four isolates of unspeciated enterococci (1.4%) also expressed this resistance phenotype. Four isolates of E. faecium and four of E. faecalis expressed the VanB-type (low-level, vancomycin only) resistance. Spain was the only country not to submit resistant E. faecium strains while resistant E. faecalis isolates came only from Spain and Italy.

Anti-Bacterial Agents↗

PubMed2000

Vancomycin resistance and antibiotic susceptibility of enterococci in raw meat.

The purpose of this study was to investigate antimicrobial resistance, in particular to vancomycin, of enterococci in samples (100) of meat (beef, chicken, turkey, lamb, and pork) sold in retail outlets of Catanzaro (Italy). Enterococci were identified to the species level. Antimicrobial susceptibility tests for a large spectrum of antibiotics including glycopeptides were performed by the disk diffusion method. Kappa statistic was used to evaluate associations of resistance to vancomycin with other antimicrobials. Enterococci were isolated from 45% of the samples, mostly from chicken meat (65.4%). Overall, 29% of samples were contaminated by vancomycin-resistant enterococci (VRE), whereas among those positive they represented 64.4% of isolates. Higher prevalence of vancomycin resistance was found in chicken samples (76.5%). The overall resistance to teicoplanin (TRE) was 30%, whereas among those positive, TRE represented 66.7% of isolates. The most frequent isolates were Enterococcus faecium (35.6%) and Enterococcus faecalis (33.3%). Resistance to vancomycin and teicoplanin was observed in 75% and 78.5% of E. faecium, and in 40% and 46.7% of E. faecalis, respectively. Most strains were susceptible to ampicillin (80%), while 88.9% were resistant to methicillin. The most effective antimicrobials were imipenem (73.3% susceptible) and rifampin (80%). The highest prevalence of resistance was for streptomycin (88.9%), tetracycline (84.4%), and erythromycin (75.6%). Resistance to vancomycin was significantly associated to methicillin, teicoplanin, erythromycin, tetracycline, and chloramphenicol. Further investigations about enterococcal colonization and infections in community and hospital subjects are needed.

Animals↗

PubMed2003

Harmonization of antimicrobial susceptibility testing among veterinary diagnostic laboratories in the five Nordic countries.

A total of 100 bacterial strains (25 Escherichia coli, 25 Salmonella enterica, 25 Staphylococcus aureus, and 25 Enterococcus strains) and four reference strains were tested for susceptibility toward 8-12 antimicrobial agents in 12 veterinary diagnostic laboratories in the five Nordic countries using routine methodology. In addition, the 25 Enterococcus strains were identified to species level. A total of 22,598 (97.2%) out of 23,259 test results were in accordance when the data were categorized as susceptible or resistant. When the reported results were categorized according to the National Committee of Clinical Laboratory Standards breakpoints, the percentage of concordant results increased to 98.4% and the performance between laboratories varied between 94.2 and 99.4% concordant results. For E. coli, S. aureus, and Salmonella, all laboratories except one had more than 97% concordant results, whereas for Enterococcus spp., two laboratories had less than 90% concordant results. Susceptibility testing of Salmonella to fluoroquinolones gave rise to almost 0.5% nonconcordant results and susceptibility testing of S. aureus to vancomycin resulted in that 1.8% of the strains were incorrectly reported as vancomycin resistant. Ten laboratories identified the Enterococcus spp. to species level. All five Enterococcus faecium and 10 Enterococcus faecalis selected from the strain collection at the Danish Veterinary Institute were correctly identified by all laboratories, whereas some problems were observed identifying other enterococcal species. This study showed a good performance and agreement in antimicrobial susceptibility testing at the 12 participating laboratories and that surveillance data covering susceptibility test results of E. coli, S. aureus, and Salmonella from animals in the Nordic countries are comparable. But it also showed that some aspects can be improved. In addition, the study showed that the different laboratories are capable of identifying E. faecalis and E. faecium.

Drug Resistance, Bacterial↗