Introduction: Enterococci are important causes of community acquired
and nosocomial infections. The increased use of antibiotics, especially
in hospitals, selects strains of enterococci which are multiple resistant
to antibiotics.
The objectives of this research are to establish what species of enterococci
prevail as cause of infection in population of Split and Dalmatia County,
and to find out if there is a difference in species distribution and frequency
of enterococci isolated from clinical samples of hospitalized patients
and outpatients, as well as their susceptibility to the most used antibiotics
in treatment of enterococcal infections: ampicillin, gentamicin, streptomycin,
vancomycin, ciprofloxacin, and, only in cause of urinary tract infection,
to nitrofurantoin.
Methods: In this study 235 isolates of enterococci from urine,
blood, sperm, wound, cervix, ear and vagina of hospitalized patients and
of outpatients in the territory of Split and Dalmatia County, Croatia during
first six months of 1997 were tested.
Identification up to the species level was made by Falcam and Collins
method and by API 20 Strep (bioMerieux, France).
Antibiotic susceptibility to ampicillin was made by microbroth dilution,
to gentamicin and streptomycin by agar dilution screening method, and to
vancomycin by E test (AB Biodisk, Sweden). Disk diffusion method was used
for testing susceptibility to ciprofloxacin and, in case of urine isolates,
to nitrofurantoin. Chi-squared test was used to test difference in resistance
among hospital and community isolates of enterococci.
Results: From 235 clinical isolates of enterococci, 106 were
from outpatients (104 E. faecalis and 2 E. faecium)
and 129 were from hospitalized patients (108 E. faecalis and 21
E.
faecium).
Ampicillin-resistant were 10,64% isolates. There were no beta-lactamase
producing isolates. High-level resistant (HLR) gentamicin isolates were
28,94% strains and 45,53% had HLR to streptomycin. Ciprofloxacin-resistant
and intermediate were 63,4% isolates. There were no vancomycin-resistant
isolates. Nitrofurantoin-resistant were 2,82% of urine isolates.
Ampicillin-resistant were 17,1% isolates from hospitalized patients
and 2,8% from outpatients. High-level resistant (HLR) gentamicin isolates
were 43,4% isolates from hospitalized patients and 11,3% from outpatients,
and HLR streptomycin isolates were 56,6% and 32,1%, respectively. Ciprofloxacin-resistant
and intermediate were 68,2% hospitalized patients isolates and 57,6% outpatients
isolates. There were no vancomycin-resistant isolates. Nitrofurantoin-resistant
were 5,9% of hospitalized patients urine isolates and there were no resistant
isolates from outpatients.
Statisticaly significant differences in enterococcal resistance among
hospitalized and outpatients have been noted in resistance to ampicillin,
gentamicin and streptomicin, but difference have not been significant for
vancomycin, ciprofloxacin and nitrofurantoin.
Conclusion: E. faecalis was the species that was mostly
isolated from clinical samples.
E. faecium was more frequently isolated from samples collected
from hospitalized patients. Statisticaly significant difference in resistance
among hospitalized and outpatients was noted in resistance to most clinically
used antibiotics: ampicillin, gentamicin and streptomicin, but difference
was not significant for vancomycin (there were no vancomycin-resistant
isolates at all), ciprofloxacin (it is not antibiotic of first choice to
treat enterococcal infections), and nitrofurantoin (antibiotic most frequently
used for treating urinary tract infections in outpatients).