The enterococcus

Characterization of enterococci isolated from human and nonhuman sources in Brazil

A total of 330 enterococci strains isolated from several human (272 strains) and animal (27) clinical specimens and environmental sources (31) in Brazil were identified to species level. Major human sources included urine (48.5%), blood (15.8%), and wounds (9.5%). Human isolates were identified as Enterococcus faecalis (90.0%), E. faecium (6.9%), E. gallinarum (1.1%), E. durans (0.8%), E. casseliflavus (0.4%), E. raffinosus (0.4%), and E. mundtii (0.4%). Strains isolated from animals were composed of E. hirae (40.7%), E. faecalis (33.3%), E. faecium (18.5%), and E. casseliflavus (7.5%). Among environmental isolates, 42.0% were E. faecalis, 35.4% E. faecium, 13.0% E. hirae, 6.4% E. casseliflavus, and 3.2% E. durans. Antimicrobial susceptibility tests were performed for 200 strains. Overall, high-level resistance (HLR) to aminoglycosides was found in 66 (33.0%) of the strains tested. HLR to gentamicin was detected in 11.5% of the strains, whereas 19.0% of the strains showed HLR to streptomycin and 26.0% showed HLR to kanamycin. Five (22.7%) of the E. faecium strains were resistant to ampicillin [minimum inhibitory concentration (MIC) > 32 micrograms/ml]. Vancomycin MIC50 and MIC90 were 2 and 4 micrograms/ml, respectively; only eight strains (identified as E. casseliflavus or E. gallinarum) had MIC of 8 micrograms/ml. No beta-lactamase activity was detected by the nitrocefin test.

Pathogenicity of the enterococcus in surgical infections

The enterococcus has been relegated to a position of unimportance in the pathogenesis of surgical infections. However the increasing prevalence and virulence of these bacteria prompt reconsideration of this view, particularly because the surgical patient has become increasingly vulnerable to infectious morbidity due to debility, immunosuppression, and therapy with increasingly potent antibiotics. The enterococcus is a versatile opportunistic nosocomial pathogen, causing such diverse infections as wound, intra-abdominal, and urinary tract infections; catheter-associated infection; suppurative thrombophlebitis; endocarditis; and pneumonia. Although surgical drainage remains the cornerstone of therapy for enterococcal infections involving a discrete focus, in the circumstances typified by the compromised surgical patient, specific antibacterial therapy directed against the enterococcus is warranted. Recent evidence indicates that parenteral antibiotic therapy for enterococcal bacteremia is mandatory and that appropriate therapy clearly reduces the number of deaths.

Nosocomial enterococcal infections: association with use of third-generation cephalosporin antibiotics

Enterococcal infections consistently account for approximately 10% of all nosocomial infections reported to the Centers for Disease Control. There is concern that an increase in nosocomial enterococcal infection is due to the increased severity of inpatient illnesses and to the widespread use of broad-spectrum beta-lactam antibiotics. Nosocomial enterococcal infections were analyzed at our medium-sized community hospital over a time period spanning 9 years. A significant increase in the infection rate was detected during the latter half of 1986. This increase was due primarily to a disproportionate rise in the incidence of the urinary tract as a site of infection. There were no associated clusters of infection, no predilection for certain patient care areas, and no preceding change in the hospital infection control policies and procedures. Total hospital use of cephalosporins remained stable during the period of increased enterococcal infections, but use of third-generation cephalosporins almost doubled in 1986 compared with the 4 preceding years. Selective pressure of third-generation cephalosporin use appeared to be a factor in the increased incidence of nosocomial enterococcal urinary tract infection.