Characterization of multiple-antibiotic-resistant Salmonella typhimurium stains: molecular epidemiology of PER-1-producing isolates and evidence for nosocomial plasmid exchange by a clone.
We characterized epidemiologic and genetic features of nosocomially originated multiple-antibiotic-resistant Salmonella typhimurium isolates from two hospitals. A total of 32 multiply resistant strains, isolated during a 28-month period, were studied. Four resistance phenotypes were distinguished on the basis of the results of disc diffusion tests. Group 1 was resistant to chloramphenicol, gentamicin, tobramycin, amikacin, and the newer cephalosporins because of the production of an extended-spectrum beta-lactamase (PER-1). Group 2 exhibited the same pattern plus resistance to sulfamethoxazole-trimethoprim (Sxt). Except for Sxt resistance, dominant phenotypes of both groups were transferred on an identical plasmid, pSTI1 (81 MDa). Group 3 was resistant to ampicillin, chloramphenicol, gentamicin, tobramycin, and Sxt. This pattern was also transferred on an 81-MDa plasmid (pSTI2) which differed from pSTI1 on the basis of EcoRI and HindIII restriction fragments. Group 4 was resistant to ampicillin, chloramphenicol, and tetracycline, and a 74-MDa nonconjugative plasmid was detected. Restriction fragment length polymorphism of RNA-encoding DNA and arbitrarily primed PCR tests revealed that bacteria from groups 1, 2, and 3 were clonally related. Epidemiologic data also supported the clonal-dissemination hypothesis. We concluded that S. typhimurium isolates acquire and exchange multiple-resistance plasmids in hospital microflora.
Vahaboglu
H
H
Kocaeli University Medical School, Turkey. vahabo@boun.edu.tr
Dodanli
S
S
Eroglu
C
C
Oztürk
R
R
Soyletir
G
G
Yildirim
I
I
Avkan
V
V
D001483:Base Sequence; D003428:Cross Infection / Q000453:epidemiology* / Q000382:microbiology*; D017931:DNA Primers / Q000235:genetics; D018432:Drug Resistance, Multiple / Q000235:genetics; D006801:Humans; D017720:Molecular Epidemiology; D010641:Phenotype; D010957:Plasmids / Q000235:genetics; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D012189:Retrospective Studies; D012480:Salmonella Infections / Q000453:epidemiology* / Q000382:microbiology*; D012486:Salmonella typhimurium / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D014421:Turkey / Q000453:epidemiology; D001618:beta-Lactamases / Q000235:genetics / Q000302:isolation & purification
D017931:DNA Primers; D001618:beta-Lactamases