BackgroundAcinetobacter baumannii is emerging as an important nosocomial pathogen. Multidrug resistance, as well as ability to withstand environmental stresses, makes eradication of A. baumannii difficult, particularly from hospital settings.ResultsOver a six-year period, 73 isolates of A. baumannii were collected from infected patients in two hospitals in Italy. While 69 out of the 73 isolates displayed identical multidrug antibiotic resistance pattern, they were susceptible to carbapenems. Genetic profiles of these 69 isolates, determined by Pulsed Field Gel Electrophoresis (PFGE), indicated that they were genetically related and could be clustered in a specific clone, called SMAL. We tested the ability of the SMAL clone to form biofilm, an important determinant for bacterial colonization of the human host and for persistence in the hospital environment. Biofilm formation by A. baumannii SMAL, measured as surface adhesion to polystyrene, is strongly affected by growth conditions, being impaired in rich growth media such as LB, while being favoured in glucose-based medium. Surface adhesion in glucose-based media is inhibited by treatment with cellulase, suggesting that it depends on production of cellulose or of a chemically related extracellular polysaccharide. Exposure of A. baumannii SMAL to subinhibitory concentrations of imipenem resulted in biofilm stimulation and increased production of iron uptake proteins. Growth in iron-supplemented medium also stimulated surface adhesion, thus suggesting that increased intracellular iron concentrations might act as an environmental signal for biofilm formation in A. baumannii SMAL.ConclusionsOur results indicate that exposure to subinhibitory concentrations of imipenem can stimulate biofilm formation and induce iron uptake in a pathogenic strain of A. baumannii, with potential implications on antibiotic susceptibility and ability to persist in the human host.

Seven patients with staphylococcal neurosurgical shunt infections were treated with intraventricular teicoplanin. Two infants received 5 mg/d, three patients received 20 mg/d, and two patients received 20 mg every other day. Six of these patients also received intravenous antibiotics. Three patients had infections caused by methicillin-susceptible Staphylococcus epidermidis, and one patient had an infection caused by methicillin-resistant S. epidermidis. Three patients were infected with Staphylococcus aureus (one with a methicillin-resistant strain and two with methicillin-susceptible strains). The mean duration of intraventricular therapy was 16 days. Sterilization of cerebrospinal fluid (CSF) was obtained after an average of 4.4 days. All patients were cured both clinically and microbiologically. No significant adverse effects were observed in any patients. Penetration of teicoplanin into the CSF after intravenous administration was poor. However, after intraventricular administration, high and prolonged peak and trough levels of teicoplanin were detected in the CSF. Bactericidal activity of the CSF was remarkable, exceeding the 1:8 dilution in the majority of the cases. The alternate-day schedule of intraventricular administration of teicoplanin was as effective as the once-daily regimen.

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OBJECTIVE: Provocative stimulation tests for growth hormone (GH) assessment have poor reproducibility and can often elicit false positive results in normal children. The aim of our study was to confirm the capability of pegvisomant as an enhancer of GH secretion in unmasking false-positive results in short children (height <-2.0 standard deviation score, SDS) undergoing GH testing. DESIGN: A prospective study was conducted between March and August 2016. Twenty short children (10 males and 10 females), aged 4.6-13.4 years, previously diagnosed as GH deficient (GHD) were included in the study. All subjects received 1 mg/kg of pegvisomant subcutaneously; three days later an insulin tolerance test (ITT) was performed. Insulin-like growth factor-I (IGF-I) was evaluated before and three days after pegvisomant administration. RESULTS: After pegvisomant priming and the ITT stimulation test, 12 out of the 20 children initially classified as GHD showed a GH peak of more than 10 ng/ml and were thus reclassified as short normal. Furthermore, a significant reduction of IGF-I was observed in the GHD group (pre IGF-I: median (IQR) 144.0 (109-248) ng/ml, post IGF-I: 98 (49-165) ng/ml; p<0.001) after pegvisomant administration. CONCLUSIONS: Pegvisomant priming before GH stimulation tests can be used to improve the reliability of the diagnostic work-up in GH deficiency.

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