Characterization of Salmonella entericaSerovar Typhimurium DT104 Isolated from Denmark and Comparison with Isolates from Europe and the United States

ABSTRACT A total of 136 isolates of Salmonella enterica serovar Typhimurium DT104 from Denmark (n = 93), Germany (n = 10), Italy (n = 4), Spain (n = 5), and the United Kingdom (n = 9) were characterized by antimicrobial resistance analysis, plasmid profiling, pulsed-field gel electrophoresis (PFGE) with the restriction enzymes XbaI and BlnI, and analysis for the presence of integrons and antibiotic resistance genes. The isolates from Denmark were from nine pig herds, while the isolates from other countries were both of animal and of human origin. All but 10 isolates were resistant to ampicillin, chloramphenicol, spectinomycin, streptomycin, sulfonamides, and tetracycline. Five isolates from the United Kingdom and Spain were sensitive to all antibiotics examined, whereas four isolates from the United Kingdom and the United States were also resistant to one or more of the antibiotics, namely, gentamicin, neomycin, and trimethoprim. All but two strains had the same PFGE profiles when the XbaI restriction enzyme was used, while seven different profiles were observed when theBlnI restriction enzyme was used. Different dominatingBlnI types were observed among European isolates compared with the types observed among those from the United States. All the isolates harbored common 95-kb plasmids either alone or in combination with smaller plasmids, and a total of 11 different plasmid profiles were observed. Furthermore, all but one of the multidrug-resistant isolates contained two integrons, ant (3")-Ia andpse-1. Sensitive isolates contained no integrons, and isolates that were resistant to spectinomycin, streptomycin, and sulfonamides had only one integron containing ant (3")-Ia. When restriction enzyme BlnI was used, the 14 isolates from one of the nine herds in Denmark showed unique profiles, whereas isolates from the remaining herds were homogeneous. Among isolates from seven of nine herds, the same plasmid profile (95 kb) was observed, but isolates from two herds had different profiles. Thus, either PFGE (withBlnI) or plasmid profiling could distinguish isolates from three of nine pig herds in Denmark. The epidemiological markers (antimicrobial susceptibility testing, plasmid profiling, and PFGE) applied demonstrated high in vivo stability in the Danish herds. This may indicate that some different strains of multidrug-resistantS. enterica serovar Typhimurium DT104 have been introduced into Danish food animal herds. The presence of isolates from six different countries with similar profiles by PFGE with XbaI and highly homogeneous profiles by PFGE with BlnI indicate that multidrug-resistant S. enterica serovar Typhimurium DT104 has probably been spread clonally in these countries. However, some minor variation could be observed by using plasmid profiling and profiling by PFGE with BlnI. Thus, a more sensitive technique for subtyping of strains of DT104 and a broader investigation may help in elucidating the epidemiological spread of DT104 in different parts of the world.

[1]  V. Agmon,et al.  Emergence of multidrug-resistant Salmonella enterica serotype Typhimurium phage-type DT104 among salmonellae causing enteritis in Israel , 1998, Epidemiology and Infection.

[2]  P. Pohl,et al.  Salmonella typhimurium phage type DT104 in Belgian livestock , 1998, Veterinary Record.

[3]  F. Aarestrup,et al.  Characterisation of recently emerged multiple antibiotic-resistant Salmonella enterica serovar typhimurium DT104 and other multiresistant phage types from Danish pig herds , 1998, Veterinary Record.

[4]  S. Rubino,et al.  IS200 fingerprint of Salmonella enterica serotype Typhimurium human strains isolated in Sardinia , 1998, Epidemiology and Infection.

[5]  F. Aarestrup,et al.  Characterisation of integrons and antibiotic resistance genes in Danish multiresistant Salmonella enterica Typhimurium DT104. , 1998, FEMS microbiology letters.

[6]  S. Rankin,et al.  Antimicrobial resistance of Salmonella enterica Typhimurium DT104 isolates and investigation of strains with transferable apramycin resistance , 1997, Epidemiology and Infection.

[7]  T. Besser,et al.  Salmonellosis associated with S typhimurium DT104 in the USA. , 1997, The Veterinary record.

[8]  E. Threlfall,et al.  Epidemiological application of differentiating multiresistant Salmonella typhimurium DT104 by plasmid profile. , 1996, Communicable disease report. CDR review.

[9]  W. Demczuk,et al.  Drug resistance, plasmids, biotypes and susceptibility to bacteriophages of Salmonella isolated from poultry in Canada. , 1996, International journal of food microbiology.

[10]  J. A. Frost,et al.  Increasing spectrum of resistance in multiresistant Salmonella typhimurium , 1996, The Lancet.

[11]  R M Hall,et al.  Gene cassettes: a new class of mobile element. , 1995, Microbiology.

[12]  J Y D'Aoust,et al.  Salmonella and the international food trade. , 1994, International journal of food microbiology.

[13]  L R Ward,et al.  A case control study of infection with an epidemic strain of multiresistant Salmonella typhimurium DT104 in England and Wales. , 1994, Communicable disease report. CDR review.

[14]  E. Threlfall,et al.  Epidemic in cattle and humans of Salmonella typhimurium DT 104 with chromosomally integrated multiple drug resistance , 1994, Veterinary Record.

[15]  R M Hall,et al.  Site-specific deletion and rearrangement of integron insert genes catalyzed by the integron DNA integrase , 1992, Journal of bacteriology.

[16]  G. Jacoby,et al.  Sequence of the PSE-1 β-Lactamase Gene , 1991, Antimicrobial Agents and Chemotherapy.

[17]  R M Hall,et al.  Site‐specific insertion of genes into integrons: role of the 59‐base element and determination of the recombination cross‐over point , 1991, Molecular microbiology.

[18]  R. Tauxe,et al.  International increase in Salmonella enteritidis: A new pandemic? , 1990, Epidemiology and Infection.

[19]  C. Wray,et al.  Differentiation of Salmonella typhimurium DT204c by plasmid profile and biotyping , 1987, Veterinary Record.

[20]  L R Ward,et al.  Characterization of plasmids conferring resistance to gentamicin and apramycin in strains of Salmonella typhimurium phage type 204c isolated in Britain , 1986, Journal of Hygiene.

[21]  S. T. Liu,et al.  Rapid procedure for detection and isolation of large and small plasmids , 1981, Journal of bacteriology.

[22]  E. Threlfall,et al.  International spread of multiresistent strains of Salmonella typhimurium phage types 204 and 193 from Britain to Europe , 1979, Veterinary Record.

[23]  L R Ward,et al.  Spread of multiresistant strains of Salmonella typhimurium phage types 204 and 193 in Britain. , 1978, British medical journal.

[24]  D J Ayers,et al.  A multiple plasmid-containing Escherichia coli strain: convenient source of size reference plasmid molecules. , 1978, Plasmid.

[25]  E. S. Anderson,et al.  Bacteriophage-typing designations of Salmonella typhimurium , 1977, Journal of Hygiene.

[26]  B. R. Callow.  A new phage-typing scheme for Salmonella typhi-murium , 1959, Journal of Hygiene.

[27]  E J Threlfall,et al.  Molecular epidemiology of antibiotic resistance genes in multiresistant epidemic Salmonella typhimurium DT 104. , 1998, Microbial drug resistance.

[28]  R. Davies,et al.  A veterinary view of salmonella in farm animals , 1996 .

[29]  T. Hald,et al.  Annual report on zoonoses in denmark 1997 , 1996 .

[30]  J. E. Olsen,et al.  Clonal lines of Salmonella enterica serotype Enteritidis documented by IS200-, ribo-, pulsed-field gel electrophoresis and RFLP typing. , 1994, Journal of medical microbiology.

[31]  G. Jacoby,et al.  Sequence of the PSE-1 beta-lactamase gene. , 1991, Antimicrobial agents and chemotherapy.

[32]  D. Vapnek,et al.  Nucleotide sequence analysis of a gene encoding a streptomycin/spectinomycin adenylyltransferase. , 1985, Plasmid.

[33]  D. Vapnek,et al.  Nucleotide sequence analysis of a gene encoding a streptomycin/spectinomycin adenyltransferase , 1985 .