Antibiotic resistance in enterococci at a teaching hospital

Treatment of pediatric febrile neutropenia in the era of vancomycin-resistant microbes

PURPOSE

The increasing frequency of Gm(+) infections in febrile neutropenic (FN) patients has resulted in increased use of vancomycin (VN). Likely as a result, VN-resistant Enterococcus (VRE) has become a significant concern in FN patients. We sought to understand how the emergence of VN resistant microbes has changed the antibiotic management of pediatric FN.

METHODS

A questionnaire was distributed by e-mail to responsible investigators of the Children's Oncology Group.

RESULTS

One hundred and thirty responses were analyzed. Forty-four percent initially used monotherapy, with 82% of those using ceftazidime. Twenty-seven used VN with another agent, generally ceftazidime. After the emergence of VRE and VN-resistant staphylococcus (VRS), monotherapy increased to 58%. Ceftazidime continued to be most frequently used. There was a 57% reduction in the use of VN with 88% of centers not currently using VN in their initial treatment of FN. Forty-seven percent of the centers that continue to use VN have VRE, while 90% that have discontinued its use have VRE/VRS.

CONCLUSIONS

Ours is the first study to survey current practices in the treatment of pediatric FN and to document changes in practice patterns due to emerging antibiotic resistance patterns. We demonstrate increased use of monotherapy for FN, and a 57% decrease in the use of VN. Local considerations influence antibiotic choices with a significant difference in VRE prevalence between those centers that continue to use VN as compared to those that have discontinued it.

Prevalence in Singapore of enterococci with high-level resistance to aminoglycosides and comparison of three methods for their detection

The first study of the prevalence in Singapore of enterococci with high-level resistance to aminoglycosides has been made in the National University Hospital. From March to June 1992, 225 isolates were studied by means of three methods: (1) use of brain-heart infusion (BHI) agar incorporating the antibiotic; (2) microdilution of the antibiotic in broth; and (3) use of high content antibiotic discs. The BHI agar was the reference method. Of the total, 49 (22%) isolates were resistant to gentamicin, 86 (38%) to streptomycin, 82 (36%) to kanamycin and 93 (41%) to one or more of the agents. Results of the disc diffusion method correlated completely with the BHI agar method. The broth microdilution method showed a 100, 90 and 96% sensitivity in relation to gentamicin, streptomycin and kanamycin, respectively, and a specificity of 100% for all three aminoglycosides. Statistical significance (P < 0.01 to P < 0.001) was demonstrated in (1) a greater incidence of enterococci with high-level resistance to aminoglycosides among blood isolates; (2) gentamicin resistance predicting kanamycin high-level resistance; and (3) more resistance to gentamicin, streptomycin and kanamycin among Enterococcus faecium isolates compared to those of Enterococcus faecalis. Beta-lactamase activity was not detected.

Frequency and antimicrobial susceptibility of clinical isolates of enterococci

A study was performed to determine the frequency and antimicrobial susceptibility of Enterococcus species in clinical specimens. Of 943 aesculin-positive isolates, 873 (92%) were identified as enterococci (737 Enterococcus faecalis, 129 Enterococcus faecium and 7 other Enterococcus species). High-level resistance to gentamicin was found in 15.2% of Enterococcus faecalis, but not in Enterococcus faecium; 58% of Enterococcus faecium were resistant to gentamicin at a concentration of 64 mg/l. None of the isolates were shown to possess vancomycin resistance.