Potentials of microbiological diagnostics in the supportive therapy of children with malignant diseases

A risk of infection in children with malignant diseases is great because of neutropenia that occurs as a complication of chemotherapy. Raised temperature is often the only sign of infection in neutropenic patients with a malignant disease, while other signs of infection may not be present. On the other hand, raised temperature need not necessarily portend an infection. Hence the need for microbiological diagnostics. Although antimicrobial therapy in neutropenic patients starts empirically, it is created according to local data on the frequency of the infective agents and their sensitivity to antimicrobial drugs. Microbiological laboratories have a lot of options at disposal to prove the presence of the etiological cause of infection, ranging from conventional coloring methods and cultivation of microorganisms to immunodiagnostics and molecular diagnostic methods. Bacteria are the most frequent infective agents in febrile neutropenic patients. Infections with gram-positive bacteria are associated with the use of intravascular catheters, whereas those with gram-negative bacteria largely stem from intestinal flora. In this group of patients the increasingly important agents of invasive infections are fungi, mostly of the Candida spp. and Aspergillus spp. genera: of viruses the most important are herpesviruses, respiratory viruses and viruses in the digestive tract.
Blood for hemoculture is an obligatory sample. Hemoculture is a standard diagnostic method to prove an infection in blood circulation. The drawback of this method is that processing will take time. The new molecular diagnostic methods, such as the realtime polymerase chain reaction (RT-PCR), allows the detection of a greater number of the most frequent pathogens (bacteria and fungi) within 6 hours, but requires sophisticated laboratory equipment, well-trained personnel and, compared with hemoculture, is much costlier. Other samples are taken in dependence on the suspected infection, and may be from the respiratory system, liquor, stool, urine, skin swabs or from skin changes. For their processing standard diagnostic methods are used to produce evidence of bacteria, fungi, viruses or parasites.

In spite of the published data on a limited value of control culture findings as predictors of infection, their processing is common in detecting colonization with resistant bacteria, as well as with bacteria and fungi which are potential pathogens for severe infections.

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