Fluconazole and itraconazole susceptibilities of Candida spp. isolated from oropharyngeal specimens and blood cultures of paediatric haematology/oncology patients.

This study examined the in vitro susceptibilities to fluconazole and itraconazole of isolates of Candida spp. from surveillance oropharyngeal specimens and blood cultures from paediatric patients with malignancy. The species distribution of 100 isolates from oropharyngeal specimens was C. albicans 86%, C. glabrata 7%, C. lusitaniae 4%, C. parapsilosis 2% and C. tropicalis 1%. From a total of nine isolates from blood cultures the species distribution was C. albicans 33.3%, C. parapsilosis 33.3 % and C. guilliermondii 33.3%. Only three of the oropharyngeal isolates were resistant to fluconazole (MIC > or = 64 mg l(-1)) and only two were resistant to itraconazole (MIC > or = 1 mg l(-1)). None of the blood culture isolates was resistant to either agent. At this centre, C. albicans is the predominant species from oropharyngeal specimens, but non-albicans Candida species predominate in blood cultures. Although resistance to fluconazole and itraconazole is rare at present, continued surveillance is warranted to monitor trends in species distribution and antifungal susceptibility.

Gingivitis and toothbrushes: potential roles in viridans streptococcal bacteraemia.

We report a case of Streptococcus oralis bacteraemia in a paediatric neutropenic patient with acute myeloid leukaemia whose predominant form of oral compromise was severe gingivitis, rather than mucositis. By phenotypic and genotypic analyses, the strain of S. oralis from blood culture was indistinguishable from an isolate from his mouth, suggesting that gingivitis may have provided a portal of entry for viridans streptococci into the bloodstream. To improve the patient's oral and dental hygiene and reduce gingivitis, conventional disposable foam toothettes were substituted with a new soft toothbrush for use as part of the oral care protocol. As there are no guidelines regarding the frequency of replacement of toothbrushes used by immunocompromised patients, the brush was swabbed regularly and culture performed to detect microbial colonization. Viridans streptococci were cultured from the toothbrush after 2 weeks of use. Phenotypic, followed by genotypic analyses, demonstrated that a strain of S. oralis from the toothbrush was indistinguishable from the strain previously isolated from blood culture and mouth. Soft toothbrushes may be useful tools for maintaining oral hygiene in immunocompromised individuals. However the results of this study indicate that regular replacement is warranted, as the toothbrush itself may become colonized with the organisms responsible for bacteraemia.

Antimicrobial susceptibility of blood culture isolates of viridans streptococci: relationship to a change in empirical antibiotic therapy in febrile neutropenia.

This study investigated the antibiotic susceptibilities of 67 isolates of viridans streptococci from 61 cases of bacteraemia in immunocompromised paediatric patients with malignancy. The majority of patients (87%) had received prior courses of empirical antibiotic therapy, which consisted of ceftazidime plus amikacin during period 1 and piperacillin/tazobactam plus amikacin during period 2. Susceptibility to vancomycin and quinupristin/dalfopristin was 100%. Susceptibility to beta-lactam antibiotics varied. For period 1, the geometric mean MICs of all beta-lactams tested against blood culture isolates (n = 31) exceeded those against isolates (n = 36) collected from blood after the change in empirical therapy (by 3.3-fold for ceftazidime, 2.8-fold for piperacillin/tazobactam and 1.6-fold for penicillin). The selection of a beta-lactam antibiotic for empirical therapy must be made with care, as repeated courses of certain agents may be more likely to select for viridans streptococci with diminished susceptibility.

Origins of Staphylococcus epidermidis and Streptococcus oralis causing bacteraemia in a bone marrow transplant patient.

Coagulase-negative staphylococcal bacteraemia in immunocompromised patients is often associated with the use of central venous catheters, while the proposed origin of viridans streptococci causing bacteraemia in this patient group is the oral cavity. This report describes an episode of polymicrobial bacteraemia caused by Staphylococcus epidermidis and Streptococcus oralis followed by several further episodes of S. epidermidis bacteraemia in a 15-year-old boy after bone marrow transplantation. Pulsed-field gel electrophoresis (PFGE) of SmaI chromosomal DNA digests was used to compare blood culture and oral isolates of S. epidermidis and Str. oralis. The results indicated that the mouth was the source of both S. epidermidis and Str. oralis causing the first episode of bacteraemia. PFGE further demonstrated that the central venous catheter was the origin of a second strain of S. epidermidis responsible for subsequent episodes of staphylococcal bacteraemia. Both the oral mucosa and central venous lines should be considered as potential sources of organisms, including coagulase-negative staphylococci, associated with bacteraemia in immunocompromised patients.

Aspergillus flavus endocarditis in a child with neuroblastoma.

We report a case of Aspergillus flavus endocarditis in a 6-year-old boy with stage IV neuroblastoma with no pre-existing cardiac disease. The infection was successfully treated with high-dose liposomal amphotericin (AmBisome) once daily. Recurrence was prevented with itraconazole oral solution once daily as maintenance therapy. Adjunctive surgery was not required. The patient's cardiac function was uncompromised, but subsequent death from progressive neuroblastoma prevented long-term follow-up.

Influence of inoculum, medium and serum on the in-vitro susceptibility of coagulase-negative staphylococci to teicoplanin and vancomycin.

The susceptibility to teicoplanin of 100 coagulase negative staphylococci, predominantly isolated from intravenous catheter tips and exit sites was determined by agar dilution on IsoSensitest media with and without the addition of 20% inactivated horse serum using an inoculum of 10(4) cfu/spot. Incorporation of serum resulted in a three-fold increase in the geometric mean MIC and a four-fold increase in the geometric mean MBC. Further tests, performed in DST and IsoSensitest medium supplemented with 20% inactivated horse serum, resulted in a wide variation in teicoplanin MICs with differences in the geometric mean MICs being up to 8.8-fold in serum media compared to unsupplemented media, whereas the MICs of vancomycin were unaffected. Under the various experimental conditions used, the susceptibility of the coagulase negative staphylococci to teicoplanin varied from 31-100%, while all were consistently susceptible to vancomycin. We therefore recommend that teicoplanin MICs be determined in the presence of serum as these are better related to serum drug levels and reflect more accurately the conditions in vivo. Trials of teicoplanin as monotherapy are required to provide further insight into the relationship between its in-vitro antibacterial activity and its clinical efficacy as the drug is easier to administer, better tolerated and less toxic than vancomycin which might compensate for its reduced activity in the presence of serum.

Selectivity in paternal and infanticidal responses by male mice: effects of relatedness, location, and previous sexual partners.

Male mice tend to be infanticidal to unrelated infants but parental to their own offspring. The present study examines three hypotheses that might explain this apparent discrimination. There was no evidence of selective infanticide toward infants encountered for the first time on the basis of kinship, location, or cues associated with previous sexual partners. However, males tended to direct more paternal responses toward their own unfamiliar infants than toward unrelated infants, infants encountered in the male's home cage than those in the cage of another male, and when cues associated with a previous sexual partner were present. Data suggested that the responses of females to male intruders might influence the responses of those males. It was concluded that the infanticidal responses of male mice are mediated by a particular state of the male but that males in a noninfanticidal state may vary their paternal responsiveness on the basis of direct and indirect cues concerning relatedness.

Responses of infant mice to odors of urine from infanticidal, noninfanticidal, and paternal male mice.

Infant mice responded differently to the odors of urine from isolated-infanticidal, isolated-noninfanticidal, and parental males. More ultrasonic vocalizations were produced in response to urine odors of parental males than to those of isolated-infanticidal males and more to infanticidal than to noninfanticidal males. Infants became agitated in the presence of urine odors of infanticidal males and moved away from the odor source whereas they tended to remain stationary in response to urine odors of parental males. The response to urine odors of noninfanticidal males was intermediate. These data support the hypothesis that infanticidal and parental states have different physiological bases and that this physiological difference results in different chemical composition of urine. The data failed to support the hypothesis that infants will attempt to conceal themselves from infanticidal males by remaining quiet.

The relationship between infanticide and pregnancy block in mice.

Newly pregnant mice are more likely to exhibit pregnancy block when females are exposed to infanticidal males rather than to noninfanticidal males. These data suggest that females are able to assess the risk to their future infants and adjust their reproductive tactic. Those females that did not exhibit pregnancy block in the presence of infanticidal males suffered a greater loss of pups than those in the presence of noninfanticidal males, demonstrating the advantage of pregnancy block. Females served by infanticidal or noninfanticidal males showed no difference in pregnancy block, but if the litter was produced, there was a greater loss of pups sired by infanticidal males.

Strain differences in the inhibition of infanticide in male mice (Mus musculus).

The mediating mechanisms for the inhibition of infanticide in male mice were examined in two strains of mice. Both copulation and postcopulatory cohabitation inhibited infanticide in CS1 males whereas only postcopulatory cohabitation inhibited infanticide in CBA males. These data illustrate the difficulties of making conclusions concerning infanticide from single studies using single strains or species.