Current advances in aptamer-assisted technologies for detecting bacterial and fungal toxins.

Infectious diseases are among the common leading causes of morbidity and mortality worldwide. Associated with the emergence of new infectious diseases, the increasing number of antimicrobial-resistant isolates presents a serious threat to public health and hospitalized patients. A microbial pathogen may elicit several host responses and use a variety of mechanisms to evade host defences. These methods and mechanisms include capsule, lipopolysaccharides or cell wall components, adhesions and toxins. Toxins inhibit phagocytosis, cause septic shock and host cell damages by binding to host surface receptors and invasion. Bacterial and fungal pathogens are able to apply many different toxin-dependent mechanisms to disturb signalling pathways and the structural integrity of host cells for establishing and maintaining infections Initial techniques for analysis of bacterial toxins were based on in vivo or in vitro assessments. There is a permanent demand for appropriate detection methods which are affordable, practical, careful, rapid, sensitive, efficient and economical. Aptamers are DNA or RNA oligonucleotides that are selected by systematic evolution of ligands using exponential enrichment (SELEX) methods and can be applied in diagnostic applications. This review provides an overview of aptamer-based methods as a novel approach for detecting toxins in bacterial and fungal pathogens.

Evaluation of thyroid status of infants in the intensive care setting.

INTRODUCTION: Previous studies report the spectrum of thyroid function abnormalities in critically-ill neonates. In this study, we evaluated the thyroid status in critically-ill neonates, and determined whether thyroid function abnormalities are more common in sick neonatal infants. METHODS: In a prospective cohort study, 67 critically-ill infants from the Neonatal Intensive Care Unit (NICU), affiliated to Shiraz University of Medical Sciences, were entered into our study. Of all the included neonates, 33 were premature and seven were under 28 weeks of gestation. In addition to the routine thyroid-stimulating hormone (TSH)-screening (capillary specimen), serum free triiodothyronine (FT3), free thyroxine (FT4) and TSH were checked using radioimmunoassay kit twice (during critical illness and before discharge from the NICU). RESULTS: It was observed that abnormal TSH levels (screening test) were about 40-fold higher in critically-ill neonates compared with healthy neonates, while more than four-fifths of them were detected in the second sampling done after recovery. The mean FT3 was significantly lower during the critical illness and it increased after recovery (2.537 and 3.232 pg/ml, respectively). Mean FT4 and mean TSH during the illness and after recovery did not have any significant difference. CONCLUSION: Thyroid function abnormalities are more common in infants under intensive care and most of them manifested as "euthyroid sick syndrome"; abnormal screening tests may be due to the transient elevation of TSH during recovery from illness. Therefore, only in cases in which TSH rises more than 15-20 mIU/L or TSH remains high for a month or longer, that treatment is needed, while other cases must be followed up by serial determination of TSH and FT4. The levels of FT3 and FT4 during the illness were not affected by the duration and severity of the illness.

C-reactive protein as an indicator of aqueductal gliosis and hydrocephaly in neonatal meningitis.

Serial C-reactive protein (CRP) measurements appear to be helpful in following clinical course and response to treatment of serious bacterial infections in neonates, such as meningitis, septicaemia and osteomyelitis. In previous studies, serial determination of serum CRP could detect potential complications of meningitis, such as subdural effusion, purulent arthritis and osteomyelitis, and secondary skin infection. We report an 11-day-old full-term male neonate with persistent positive CRP after treatment of bacterial meningitis, and who developed hydrocephaly at follow-up. We concluded that positive CRP was secondary to aqueduct gliosis; therefore monitoring of serum CRP levels in infants with bacterial meningitis represented useful information, not only in persistent or secondary infection, but also for destructive complications of meningitis.