[Infections in immunosuppressed children]. / Infeksjoner hos immunsupprimerte barn.

BACKGROUND: Children undergoing transplantation or treatment for cancer have periods with severe immunosuppression; hence they are very susceptible to infections. A bacterial infection can rapidly become life threatening, and it is crucial to promptly start antibiotic treatment. MATERIALS AND METHODS: The background for this article is a two-day discussion among Norwegian paediatricians about infections in immunosuppressed children. In addition we have reviewed the literature by searches in PubMed, reference books and international guidelines. RESULTS AND INTERPRETATION: When a neutropenic patient becomes febrile, one should quickly do a thorough clinical examination, secure relevant microbiological samples, and start treatment with broad-spectrum antibiotics. As standard treatment for Norwegian children we recommend a combination of intravenous ampicillin and gentamicin. Patients who have clinical signs of septic shock should be given cefotaxime and gentamicin. If they get worse or show no signs of recovery after 3 to 5 days, a change to monotherapy with cefotaxime is recommended. Patients already treated with cefotaxime should be switched to meropenem, possibly in combination with vancomycin. Antifungal and/or anti-anaerobic treatment should also be considered.

Frequency of disinfectant resistance genes and genetic linkage with beta-lactamase transposon Tn552 among clinical staphylococci.

A total of 61 strains of Staphylococcus aureus and 177 coagulase-negative staphylococcal strains were isolated from the blood of patients with bloodstream infections and from the skin of both children under cancer treatment and human immunodeficiency virus-positive patients. The MIC analyses revealed that 118 isolates (50%) were resistant to quaternary ammonium compound-based disinfectant benzalkonium chloride (BC). The frequencies of resistance to a range of antibiotics were significantly higher among BC-resistant staphylococci than among BC-sensitive staphylococci. Of 78 BC-resistant staphylococcal isolates, plasmid DNA from 65 (83%), 2 (3%), 43 (55%), and 15 (19%) isolates hybridized to qacA or -B (qacA/B), qacC, blaZ, and tetK probes, respectively. The qacA/B and blaZ probes hybridized to the same plasmid in 19 (24%) staphylococcal strains. The plasmids harboring both qacA/B and blaZ genes varied from approximately 20 to 40 kb. The Staphylococcus epidermidis Fol62 isolate, harboring multiresistance plasmid pMS62, contained qacA/B and blaZ together with tetK. Molecular and genetic studies indicated different structural arrangements of blaZ and qacA/B, including variable intergenic distances and transcriptional directions of the two genes on the same plasmid within the strains. The different organizations may be due to the presence of various genetic elements involved in cointegration, recombination, and rearrangements. These results indicate that qac resistance genes are common and that linkage between resistance to disinfectants and penicillin resistance occurs frequently in clinical isolates in Norway. Moreover, the higher frequency of antibiotic resistance among BC-resistant strains indicates that the presence of either resistance determinant selects for the other during antimicrobial therapy and disinfection in hospitals.