High Prevalence of Vancomycin-Resistant Enterococci in Swedish Sewage

ABSTRACT In Europe the use of the growth promoter avoparcin is considered to have selected for vancomycin-resistant enterococci (VRE). Sweden ceased using avoparcin in 1986, and only occasional cases of VRE from hospitals have been reported since 1995. Within the framework of a European study, samples from urban raw sewage, treated sewage, surface water, and hospital sewage in Sweden (n = 118) were screened for VRE. Surprisingly, VRE were isolated from 21 of 35 untreated sewage samples (60%), from 5 of 14 hospital sewage samples (36%), from 6 of 32 treated sewage samples (19%), and from 1 of 37 surface water samples. Thirty-five isolates from 33 samples were further characterized by geno- and phenotyping, MIC determination, and PCR analysis. Most isolates (30 of 35) carried the vanA gene, and the majority (24 of 35) of the isolates were Enterococcus faecium. Most of the VRE were multiresistant. The typing revealed high diversity of the isolates. However, one major cluster with seven identical or similar isolates was found. These isolates came from three different sewage treatment plants and were collected at different occasions during 1 year. All VRE from hospital sewage originated from one of the two hospitals studied. That hospital also had vancomycin consumption that was 10-fold that of the other. We conclude that VRE were commonly found in sewage samples in Sweden. The origin might be both healthy individuals and individuals in hospitals. Possibly, antimicrobial drugs or chemicals released into the sewage system may sustain VRE in the system.

[1]  M. Arthur,et al.  Genetics and mechanisms of glycopeptide resistance in enterococci , 1993, Antimicrobial Agents and Chemotherapy.

[2]  M. Gilmore,et al.  Multiple-drug resistant enterococci: the nature of the problem and an agenda for the future. , 1998, Emerging infectious diseases.

[3]  A. Blanch,et al.  Identification of Enterococcus spp. with a Biochemical Key , 1999, Applied and Environmental Microbiology.

[4]  A. Sundsfjord,et al.  Intrahospital spread of vancomycin-resistant Enterococcus faecium in Sweden. , 1997, Scandinavian journal of infectious diseases.

[5]  E. Stobberingh,et al.  Epidemiology of resistance to antibiotics. Links between animals and humans. , 2000, International journal of antimicrobial agents.

[6]  H. Abednazari,et al.  Antimicrobial susceptibility patterns of enterococci in intensive care units in Sweden evaluated by different MIC breakpoint systems. , 2001, The Journal of antimicrobial chemotherapy.

[7]  P. Courvalin,et al.  Detection of glycopeptide resistance genotypes and identification to the species level of clinically relevant enterococci by PCR , 1995, Journal of clinical microbiology.

[8]  F. Aarestrup,et al.  Glycopeptide susceptibility among Danish Enterococcus faecium and Enterococcus faecalis isolates of animal and human origin and PCR identification of genes within the VanA cluster , 1996, Antimicrobial agents and chemotherapy.

[9]  M. Ploy,et al.  Prevalence of Vancomycin-Resistant Enterococci in Fecal Samples from Hospitalized Patients and Nonhospitalized Controls in a Cattle-Rearing Area of France , 2000, Journal of Clinical Microbiology.

[10]  H. Claus,et al.  Environmental strains of Enterococcus faecium with inducible high-level resistance to glycopeptides. , 1993, FEMS microbiology letters.

[11]  N. Woodford,et al.  Glycopeptide-resistant enterococci isolated from uncooked meat. , 1996, The Journal of antimicrobial chemotherapy.

[12]  Janice Bates,et al.  Evidence for an animal origin of vancomycin-resistant enterococci , 1993, The Lancet.

[13]  F M Aarestrup,et al.  Occurrence of glycopeptide resistance among Enterococcus faecium isolates from conventional and ecological poultry farms. , 1995, Microbial drug resistance.

[14]  J. Bates.  Epidemiology of vancomycin-resistant enterococci in the community and the relevance of farm animals to human infection. , 1997, The Journal of hospital infection.

[15]  R. Hakenbeck,et al.  Enterococcus faecium strains with vanA-mediated high-level glycopeptide resistance isolated from animal foodstuffs and fecal samples of humans in the community. , 1995, Microbial drug resistance.

[16]  Ronald N. Jones,et al.  Molecular Analysis of Tn1546 inEnterococcus faecium Isolated from Animals and Humans , 1998, Journal of Clinical Microbiology.

[17]  E. Bruck,et al.  National Committee for Clinical Laboratory Standards. , 1980, Pediatrics.

[18]  W. Martone.  Spread of Vancomycin-Resistant Enterococci: Why Did It Happen in the United States? , 1998, Infection Control & Hospital Epidemiology.

[19]  O. Cars,et al.  Ampicillin-resistant enterococci in a Swedish university hospital: nosocomial spread and risk factors for infection. , 2001, Scandinavian journal of infectious diseases.

[20]  P. Mertens,et al.  High prevalence of colonization with vancomycin- and pristinamycin-resistant enterococci in healthy humans and pigs in The Netherlands: is the addition of antibiotics to animal feeds to blame? , 1997, The Journal of antimicrobial chemotherapy.

[21]  R. Weinstein,et al.  External sources of vancomycin-resistant enterococci for intensive care units. , 1998, Critical Care Medicine.

[22]  T. Frieden,et al.  Emergence of vancomycin-resistant enterococci in New York City , 1993, The Lancet.

[23]  C. Greko,et al.  The usage of veterinary antibacterial drugs for mastitis in cattle in Norway and Sweden during 1990-1997. , 1999, Preventive veterinary medicine.

[24]  K. Tullus,et al.  Biochemical fingerprinting compared with ribotyping and pulsed-field gel electrophoresis of DNA for epidemiological typing of enterococci , 1995, Journal of clinical microbiology.

[25]  A. Melhus,et al.  First documented isolation of vancomycin-resistant Enterococcus faecium in Sweden. , 1996, Scandinavian journal of infectious diseases.

[26]  C. Greko.  Antibiotics as growth promoters. , 1999, Acta veterinaria Scandinavica. Supplementum.

[27]  Mary Jane Ferraro,et al.  Methods for dilution antimicrobial susceptibility tests for bacteria that grow aerobically : approved standard , 2000 .

[28]  P. Linden,et al.  Vancomycin-resistant enterococci: the clinical effect of a common nosocomial pathogen. , 1999, Diagnostic microbiology and infectious disease.

[29]  D. Pegues,et al.  Emergence and dissemination of a highly vancomycin-resistant vanA strain of Enterococcus faecium at a large teaching hospital , 1997, Journal of clinical microbiology.

[30]  R. Möllby,et al.  The PhP RS system. A simple microplate method for studying coliform bacterial populations , 1993 .

[31]  K Kümmerer,et al.  Drugs in the environment: emission of drugs, diagnostic aids and disinfectants into wastewater by hospitals in relation to other sources--a review. , 2001, Chemosphere.

[32]  R Hirsch,et al.  Occurrence of antibiotics in the aquatic environment. , 1999, The Science of the total environment.

[33]  O. Cars,et al.  Near Absence of Vancomycin-Resistant Enterococci but High Carriage Rates of Quinolone-Resistant Ampicillin-Resistant Enterococci among Hospitalized Patients and Nonhospitalized Individuals in Sweden , 1999, Journal of Clinical Microbiology.

[34]  V. Harwood,et al.  Vancomycin-Resistant Enterococcus spp. Isolated from Wastewater and Chicken Feces in the United States , 2001, Applied and Environmental Microbiology.