Antibiotic resistance patterns among blood culture isolates in a Danish county 1981-1995

Abstract

All episodes of bacteraemia during a 15-year period (1981-1995) in the County of Northern Jutland, Denmark, were analysed with regard to antibiotic resistance. A total of 8840 isolates from 7938 episodes of bacteraemia was identified. Over time, no changes in bacterial aetiology were noted. Three isolates of Staphylococcus aureus were methicillin resistant (0.2%) and six were gentamicin resistant (0.4%). Among coagulase-negative staphylococci a 14% increase in resistance to penicillin was observed (95% confidence intervals, CI: 2-26%). Likewise, the frequency of resistance to methicillin, gentamicin and erythromycin increased, the corresponding figures being 38% (CI: 26-50%), 26% (CI: 14-38%) and 32% (CI: 16-50%), respectively, whereas a 14% decrease in resistance to streptomycin was recorded (CI: 4-24%). A 20% (CI: 2-37%) increase of coagulase-negative staphylococci resistant to three or more antibiotics was observed. The frequency of ampicillin resistance increased by 9% among Escherichia coli (CI: 4-13%) and by 10% (CI: 6-14%) in all Enterobacteriaceae. Among Enterobacteriaceae the level of resistance to third-generation cephalosporins, carbapenems, aminoglycosides and fluoroquinolones remained low (< 1 YO). The frequency of resistance to three or more antibiotics remained fairly stable among Enterobacteriaceae, although a slight increase was noted among E. coli (5%; CI: 0-10%) The recommended regimen for empirical antibiotic treatment in this region (a combination of penicillin G or ampicillin and an aminoglycoside) provided an overall coverage of 94% (CI: 94-95%), although a slight decrease was noted at the end of the period. In conclusion, acquired antibiotic resistance was maintained at a low level compared with most other European countries and regions during the 15-year period studied.

Antibiotic resistance in bacterial isolates from laboratory animal colonies naive to antibiotic treatment

“…The lower frequency of resistance is meant to be caused by restrictions in the use of antibiotics in cattle (Aarestrup & Jensen 1998). Danish human isolates of S. aureus are sensitive to the other antibiotics in our tests (Kristensen et al 1999), while our isolates from antibiotic-naive animals were generally resistant to streptomycin and sulphonamamides and also showed some vancomycin resistance, while the sensitivity to gentamicin and erythromycine is in accordance with observations on human isolates. Our isolates from rats and mice were generally found to be resistant to sulphonamides.…”

“…'" •.. •.. amoxicillin seems to be far more common in human isolates (Dornbusch et al 1998, Kristensen et al 1999. The high number of E. coli isolates that we found to be resistant to streptomycin and sulphonamides is analogous to findings in farm pigs, but seem to be higher than findings in farm cattle (Aarestrup et al 1998).…”

“…Our E, coli isolates from minipigs, rodents and rabbits seem to be far less resistant towards sulphonamides, trimethoprim and the combination of the two, than it is the case with farm animals, i.e. cattle and pigs (Aarestrup et al 1998), and with humans (Dornbusch et al 1998, Kristensen et al 1999. Although our S. aureus isolates from rats and mice show the same frequency of penicillin resistance as in humans, these studies cannot support the proposed theory that S. aureus in laboratory animal colonies derives from the normal flora of the human caretakers (Wullenweber et al 1990).…”

Shortening the course of antibiotic treatment in the intensive care unit

“…Combining two or three narrower spectrum antibiotics could provide similar antimicrobial cover without promoting resistance to last-chance antibiotics. Isolates from bacteremic patients over a 14-year period in Denmark were found to have very low rates of resistance (<1%) to fluoroquinolones, carbapenems and third-generation cephalosporins [64]. The authors attribute this to the standard antibiotic regimen of penicillin G or ampicillin plus an aminoglycoside, and a similar combination approach could be used to provide broad-spectrum cover while alleviating the selection pressure on resistant organisms.…”

Untitled

“…In the County of Northern Jutland, Denmark, all bacter-aemia were analysed with regard to antibiotic resistance over a 14-year period (1981-1995) [39]. A total of 8840 isolates from 7938 episodes of bacteraemia were identified.…”