N. London

Resistance in faecal Escherichia coli isolated from pigfarmers and abattoir workers.

Faecal samples collected from three populations of healthy adult volunteers (290 pigfarmers, 316 abattoir workers, 160 (sub)urban residents) living in the south of The Netherlands were analysed for the prevalence and degree of antibiotic resistance of Escherichia coli. Significant differences in prevalence of resistance to amoxicillin, neomycin, oxytetracycline, sulfamethoxazole and trimethoprim were observed. The pigfarmers showed the highest percentages of resistance and the (sub)urban residents the lowest. In contrast no significant differences in high degrees of resistance were observed, except for neomycin. Although both pigfarmers and abattoir workers have regular contact with pigs differences in prevalences of resistance were observed. However, because abattoir workers with intensive and less intensive pig(carcass) contact did not show significant differences, this is probably not the only important source of resistant E. coli in pigfarmers. The high antibiotic use by pigfarmers (5%) and abattoir workers (8%) than by (sub)urban residents (0%) did not result in significantly different resistance percentages.

Different Levels of Genetic Homogeneity in Vancomycin-Resistant and -Susceptible Enterococcus faecium Isolates from Different Human and Animal Sources Analyzed by Amplified-Fragment Length Polymorphism

ABSTRACT The genetic relationship among fecal vancomycin-resistant Enterococcus faecium (VREF) and vancomycin-susceptible E. faecium (VSEF) isolates (n = 178) from the same populations of pigs, human healthy volunteers, and hospitalized patients (from The Netherlands) and chickens (from The Netherlands and Greece) was studied by amplified-fragment length polymorphism (AFLP). The majority of VREF isolates from pigs, healthy volunteers, and hospitalized patients grouped together (genetic similarity, ≥65%). In a previous AFLP study by our group the VREF isolates from hospitalized patients grouped separately, most likely because these were clinical and not fecal isolates as in the present study. Furthermore, VSEF isolates from humans and pigs were found much more genetically diverse than VREF isolates, whereas VREF and VSEF isolates from chickens clustered together in a separate genogroup (genetic similarity, ≥65%), a pattern clearly distinct from the patterns for human and pig isolates. The present study suggests that pigs are a more important source of VREF for humans than chickens and that human- and pig-derived VSEF isolates seem much more heterogeneous than VREF isolates.

Prevalence of Macrolide Resistance Genes in Clinical Isolates of the Streptococcus anginosus(“S. milleri”) Group

ABSTRACT Twenty-two unrelated erythromycin-resistant anginosus group strains (3.2% resistance rate) were assessed for mechanisms of resistance.Streptococcus anginosus accounted for 16 of the 22 isolates. Fifteen isolates harbored the erm(B) gene. Theerm(TR) and the mef(E) genes were carried by two isolates each. In three isolates, none of these resistance genes was detected by PCR.

Carriage of antibiotic-resistant Escherichia coli by healthy volunteers during a 15-week period

Escherichia coli strains (n=678 and n=670) isolated from faecal samples from 90 and 93 healthy volunteers of two cities, Weert and Roermond respectively, were analysed for their susceptibility to 12 antimicrobial agents during a 15-week period. Significant differences between both cities in the distribution of the MIC values were observed for apramycin, chloramphenicol, kanamycin, neomycin, nitrofurantoin, sulfamethoxazole and trimethoprim. For Weert (n=678) the antibiotic resistance percentages varied from 0.4% for nalidixic acid to 26.7% for sulfamethoxazole. For Roermond (n=670) the figures varied from 0.6% for nitrofurantoin to 37.5% for sulfamethoxazole. Resistance to amoxicillin/clavulanate was not found in either city. The most frequent pattern was resistance to sulfamethoxazole only, followed by resistance to oxytetracycline, streptomycin and sulfamethoxazole. In each individual there was only a small variation in resistance patterns of the isolates, i. e. the majority had one (n=51) or two (n=63) patterns with a maximum of five during the 15-week period. A fully susceptible pattern was found in the strains from 38 individuals. Stämme vonEscherichia coli, (n=678 und n=670), die aus Stuhlproben von jeweils 90 und 93 gesunden Freiwilligen aus zwei Städten, Weert und Roermond, gewonnen wurden, wurden auf ihre Empfindlichkeit gegenüber 12 antimikrobiellen Substanzen geprüft. Die Untersuchung lief über 15 Wochen. Für Apramycin, Chloramphenicol, Kanamycin, Neomycin, Nitrofurantoin, Sulfamethoxazol und Trimethoprim fanden sich zwischen den beiden Städten signifikante Unterschiede in den MHK-Werten. Für Weert (n=678) fanden sich Resistenzraten, die von 0,4% bei Nalidixinsäure bis 26,7% für Sulfamethoxazol reichten. In Roermond (n=670) variierten die Resistenzraten von 0,6% für Nitrofurantoin bis 37,5% für Sulfamethoxazol. In keiner der beiden Städte fand sich Resistenz gegenüber Amoxicillin-Clavulansäure. Als häufigstes Muster fand sich Resistenz gegen Sulfamethoxazol allein, es folgten Resistenz gegen Oxytetracyklin, Streptomycin und Sulfamethoxazol. Die intraindividuellen Resistenzmuster der Isolate variierten nur sehr wenig, das heißt, die meisten hatten Resistenz gegen ein (n=51) oder zwei (n=63) Antibiotika, maximal fünf während der 15 Wochen. Bei 38 Personen zeigten alle Stämme volle Empfindlichkeit gegen die Testsubstanzen.SummaryEscherichia coli strains (n=678 and n=670) isolated from faecal samples from 90 and 93 healthy volunteers of two cities, Weert and Roermond respectively, were analysed for their susceptibility to 12 antimicrobial agents during a 15-week period. Significant differences between both cities in the distribution of the MIC values were observed for apramycin, chloramphenicol, kanamycin, neomycin, nitrofurantoin, sulfamethoxazole and trimethoprim. For Weert (n=678) the antibiotic resistance percentages varied from 0.4% for nalidixic acid to 26.7% for sulfamethoxazole. For Roermond (n=670) the figures varied from 0.6% for nitrofurantoin to 37.5% for sulfamethoxazole. Resistance to amoxicillin/clavulanate was not found in either city. The most frequent pattern was resistance to sulfamethoxazole only, followed by resistance to oxytetracycline, streptomycin and sulfamethoxazole. In each individual there was only a small variation in resistance patterns of the isolates, i. e. the majority had one (n=51) or two (n=63) patterns with a maximum of five during the 15-week period. A fully susceptible pattern was found in the strains from 38 individuals.ZusammenfassungStämme vonEscherichia coli, (n=678 und n=670), die aus Stuhlproben von jeweils 90 und 93 gesunden Freiwilligen aus zwei Städten, Weert und Roermond, gewonnen wurden, wurden auf ihre Empfindlichkeit gegenüber 12 antimikrobiellen Substanzen geprüft. Die Untersuchung lief über 15 Wochen. Für Apramycin, Chloramphenicol, Kanamycin, Neomycin, Nitrofurantoin, Sulfamethoxazol und Trimethoprim fanden sich zwischen den beiden Städten signifikante Unterschiede in den MHK-Werten. Für Weert (n=678) fanden sich Resistenzraten, die von 0,4% bei Nalidixinsäure bis 26,7% für Sulfamethoxazol reichten. In Roermond (n=670) variierten die Resistenzraten von 0,6% für Nitrofurantoin bis 37,5% für Sulfamethoxazol. In keiner der beiden Städte fand sich Resistenz gegenüber Amoxicillin-Clavulansäure. Als häufigstes Muster fand sich Resistenz gegen Sulfamethoxazol allein, es folgten Resistenz gegen Oxytetracyklin, Streptomycin und Sulfamethoxazol. Die intraindividuellen Resistenzmuster der Isolate variierten nur sehr wenig, das heißt, die meisten hatten Resistenz gegen ein (n=51) oder zwei (n=63) Antibiotika, maximal fünf während der 15 Wochen. Bei 38 Personen zeigten alle Stämme volle Empfindlichkeit gegen die Testsubstanzen.

Antibiotic resistance of enterobacteriaceae isolated from the faecal flora of fattening pigs

From June 1991 to April 1992 407 faecal samples were collected from three groups of pigs (I n = 248, II n = 87, III n = 72) at a pig fattening farm to determine the prevalence and the degree of antibiotic resistance of Enterobacteriaceae as well as the antibiotic susceptibility of the strains isolated. Despite the absence of mass medication during the observation period, the prevalence of resistance to the most commonly used antimicrobial agents in veterinary medicine was high (range amoxicillin 70%-97%, oxytetracycline 89%-100%, sulfamethoxazole 88%-100%, trimethoprim 78%-100%). The high degree of resistance to oxytetracycline and sulfamethoxazole ranged from 8%-67% and 4%-46%, respectively. The percentage of the isolated Escherichia coli strains resistant to oxytetracycline, streptomycin and sulfamethoxazole ranged from 49% to 68%; the other agents tested showed lower percentages (0-13%). Resistance to three or more antibiotics was observed in 43% of the isolates. Of the 52 resistance patterns that could be distinguished, 51% was accounted by only four patterns: oxytetracycline+streptomycin+sulfamethoxazole 20%, sulfamethoxazole 12%, streptomycin+sulfamethoxazole 11% and streptomycin+oxytetracycline 8%.

Value of phenotyping methods as an initial screening of Pseudomonas aeruginosa in epidemiologic studies.

SummaryWhen studying the epidemiology ofPseudomonas aeruginosa, determination of the similarity of isolates is crucial. In the present study the distinctive capacity of four phenotyping methods (antibiotic susceptibility patterns, serotyping, phage-typing and outer membrane protein [OMP] profile analysis) was determined and compared to pulsed-field gel electrophoresis (PFGE) of enzyme restricted chromosomal DNA. In all, 91 isolates ofP. aeruginosa were cultured from ten patients. Antibiotic susceptibility patterns were concordant for all isolates. Serotyping yielded five, phage-typing eight, OMP profile analysis nine and PFGE seven distinct types ofP. aeruginosa. Compared to PFGE, the distinctive capacities were 89% (81/91) for serotyping, 87% (79/91) for phage-typing, and 90% (82/91) for OMP profile analysis. When serotyping results were different, PFGE types also were different (exclusiveness 100%). However, isolates with the same serotype may have various PFGE patterns. In contrast, isolates with similar PFGE patterns could have different phage-types or OMP types. For the study of isolates ofP. aeruginosa, serotyping provides a good initial selection to reduce the number of isolates that need to be genotyped.