Evaluation of Antimicrobial Therapy of Blood Culture Positive Healthcare-Associated Infections in Children

Aim

Knowledge of the quality of antimicrobial therapy (AMT) used for invasive healthcare-associated infections (HAIs) in paediatrics is scarce. Influence of the final information about the isolated pathogen on the subsequent targeted AMT was investigated in our study.

Methods

Data on 149 children (0–17 years) with blood culture positive HAIs were collected. The causative microbes under investigation were Staphylococcus aureus, Staphylococcus epidermidis, streptococci, Gram negative rods, and mixed infections were likewise included. For adjusting the antimicrobial regimen, an expert panel evaluated the quality of the targeted AMT and the delay of 72 hours after final microbiology results. AMT was regarded as inappropriate if the pathogen was totally resistant to the used antimicrobials (i) or if the chosen therapy was of not optimal efficacy against the pathogen (ii).

Results

17% of the patients received inappropriate AMT. Half of these infections 13/26 (50%) were treated with an antimicrobial to which the isolate was resistant. Three (3/13, 23%) of these patients received antimicrobials which were totally ineffective according to in vitro data. Suboptimal or too broad spectrum AMT was administered to 13/26 (50%) patients. The most common causes of inappropriate use were the use of beta-lactams in oxacillin-resistant Staphylococcus epidermidis infections and vancomycin given in oxacillin-sensitive Staphylococcus aureus infections.

Conclusion

Approximately 17% of the selected cohort received inappropriate AMT. More attention should be paid to the appropriate use of antimicrobials, and training of prescribers should be urgently provided.     

Increased apoptosis occurring during the first wave of spermatogenesis is stage-specific and primarily affects midpachytene spermatocytes in the rat testis

The physiological apoptosis that occurs in immature testis appears to be necessary for the maturation of this tissue. Thus, inhibition of the early apoptotic wave associated with the first round of spermatogenesis is followed by accumulation of spermatogonia and infertility later in life. To identify the cell types undergoing apoptosis in immature rat testis and to characterize the relationship between this apoptosis and progression of the first wave of spermatogenesis, sequential viable segments of seminiferous tubules from 8-, 18-, and 26-day-old rats were examined under a phase-contrast microscope. One novel observation was the existence of pronounced stage-specificity during the peak of apoptosis at the very early postnatal ages of 18 and 26 days. Increased apoptosis of pachytene spermatocytes in stages VII-VIII was the major feature that distinguished immature spermatogenesis from the corresponding adult process. The frequency of apoptosis among type A spermatogonia in immature stages IX-I was also elevated in comparison to the corresponding mature stages. The age-related peak of apoptosis was mediated by caspase 3; furthermore, stage-dependent expression of Bax in midpachytene spermatocytes was observed in the 18- and 26-day-old testis. These observations suggest that this Bax-regulated, caspase 3-mediated, increased apoptosis of midpachytene spermatocytes during the first wave of immature spermatogenesis represents a major difference in comparison to apoptosis occurring in the mature testis, and it may play an important regulatory role in establishing spermatogenesis in the rat testis.     

Fishing-induced changes in predation pressure by perch (<Emphasis Type="Italic">Perca fluviatilis</Emphasis>) regulate littoral benthic macroinvertebrate biomass,density, and community structure

We aimed to study whether the varying changes in predation pressure by perch (Perca fluviatilis) reflect the biomass, density, and community structure of the benthic macroinvertebrates. Prey preference is size-dependent, and overall predation pressure is density dependent, and thus the size structure of the P. fluviatilis population should affect the structure of the macroinvertebrate community, and the population density of P. fluviatilis should reflect the overall density of benthic macroinvertebrates. We sampled the littoral benthic community in a boreal lake that had been divided into two parts that were subjected to two different fishing procedures during 2007–2012 period and analyzed the macroinvertebrate diet of fish. The benthic macroinvertebrate community reflected the predation pressure. Total macroinvertebrate biomass increased during the study period in the lake division with a non-size-selective fishing procedure (NSF), i.e., all invertivorous perch size-classes targeted, but decreased in the section with negatively size-selective fishing procedure (SSF), i.e., large invertivorous individuals ≥ 16 cm were not targeted. This difference was a result of the increase in large-sized species, such as Odonata, for the NSF procedure and decrease in the SSF procedure. In contrast to total biomass, total macroinvertebrate density did not show a response to predator size structure but rather total macroinvertebrate density decreased with increasing fish density. The study demonstrates the effect of predation pressure of P. fluviatilis on benthic communities, thus highlighting the keystone predator role of the species in boreal lakes and gives more insight on the multiple effects of fish predation on littoral benthic communities.     

Stereospecific hydrolysis of 3-(4-methoxyphenyl)glycidic ester in supercritical carbon dioxide by immobilized lipase

In the hydrolysis of racemic 3-(4-methoxyphenyl)glycidic acid methyl ester by immobilized Mucor miehel lipase in supercritical CO₂ the initial hydrolysis rate of the (2S,3R)-form was faster than the rate of the (2R,3S) -form. The stereoisomeric excess of the (2R,3S)-form reached 87 % at 53 % total conversion level. The water content of the reaction mixture and the initial concentration of the 3-(4-methoxyphenyl) glycidic acid methyl ester had no effect on isomeric purity. The reaction rate in supercritical CO₂ was considerably faster than in toluene/water -mixture.     

Synthesis, structure and polymerization behavior of tri- and dichloroaminopyridinato complexes of titanium

Three 2-phenylaminopyridine (Ap) complexes of types ApTiCl₃ and Ap₂TiCl₂ were characterized with X-ray diffraction. The complexes were studied as polymerization catalysts using MAO as cocatalyst. In ethylene polymerization, the catalysts showed moderate activities between 65 and 285 kg PE mol⁻¹ Ti⁻¹ h⁻¹ and the molecular weight distributions were between 2.5 and 4.2, and the molar masses were between 135 000 and 804 000 kg/mol.     

Mieotic micronuclei induced by X-rays in early spermatids of the rat

In mutagenicity studies a rapid detection of chromosomal damage in mammalian germ cells would be very valuable. Encouraged by the usefulness of the bone-marrow micronucleus test, we applied an analogous method to the assay of micronuclei induced during meiotic reduction divisions in the adult male rat by X-irradiation. The micronuclei were observed in early post-meiotic cells which were enriched using a transillumination phase-contrast microscopic method. The frequency of micronuclei was scored at various dose levels and at various time intervals.The results indicate a linear increase in frequency of micronuclei 24 h after X-irradiation with doses of 0, 10, 50, 150, 300 and 600 rad. The highest frequency of micronuclei was observed after 900 rad whereas lower frequencies were found after 1200 rad. The lowest dose giving a statistically significant increase above the control level was 50 rad.The stages of meiosis showed different sensitivities to the chromosome-breaking action of X-rays. The maximal incidence of micronuclei was found 18 h after irradiation which was considered to reflect the great radiosensitivity of diakinesis-metaphase I. The anesthetized group of control animals showed a slightly higher frequency of micronuclei than the non-anesthetized control. Potentials of the new method for mutagen testing are discussed.     

Choosy egg parasitoids: Specificity of oviposition-induced pine volatiles exploited by an egg parasitoid of pine sawflies

Generalist parasitoids are well‐known to be able to cope with the high genotypic and phenotypic plasticity of plant volatiles by learning odours during their host encounters. In contrast, specialised parasitoids often respond innately to host‐specific cues. Previous studies have shown that females of the specialised egg parasitoid Chrysonotomyia ruforum Krausse (Hymenoptera: Eulophidae) are attracted to volatiles from Pinus sylvestris L. induced by the egg deposition of its host Diprion pini L. (Hymenoptera: Diprionidae), when they have previously experienced pine twigs with host eggs. In this study we investigated by olfactometer bioassays how specifically C. ruforum responded to oviposition‐induced plant volatiles. Furthermore, we studied whether parasitoids show an innate response to oviposition‐induced pine volatiles. Naïve parasitoids were not attracted to oviposition‐induced pine volatiles. The attractiveness of volatiles from pines carrying eggs was shown to be specific for the pine and herbivore species, respectively (species specificity). We also tested whether not only oviposition, but also larval feeding, induces attractive volatiles (developmental stage specificity). The feeding of D. pini larvae did not induce the emission of P. sylvestris volatiles attractive to the egg parasitoid. Our results show that a specialist egg parasitoid does not innately show a positive response to oviposition‐induced plant volatiles, but needs to learn them. Furthermore, the results show that C. ruforum as a specialist does not learn a wide range of volatiles as some generalists do, but instead learns only a very specific oviposition‐induced plant volatile pattern, i.e., a pattern induced by the most preferred host species laying eggs on the most preferred food plant.     

The effect of chemical cleansing procedures combined with peracetic acid-ethanol sterilization on biomechanical properties of cortical bone.

Peracetic acid-ethanol sterilization (PES) with a preceding delipidation step is an effective sterilization method for allograft bone, but its influence on biomechanical properties of bone has not been studied. The aim of this study was to evaluate the effects of different incubation times of water, hydrogen peroxide and alcohol cleansing procedures combined with PES on biomechanical properties of freeze-dried cortical bone. These effects were studied by performing three-point bending tests on cortical samples. The lyophilized cortical samples were rehydrated prior to mechanical testing. The bending strength and the absorbed energy of the processed cortical samples were increased slightly but the Young's modulus was decreased compared to unprocessed samples. However, when the residual moisture content of the processed cortical samples was reduced from <5% to 0% all the biomechanical properties studied were significantly decreased. Hexane elution was used to determine the residual fat content of the processed cortical bone. Reducing the incubation time in cleansing had no effect on the residual fat content of the bone samples. Our in vitro study indicates that the cleansing procedure proposed combined with PES affects the biomechanical properties of cortical bone only on a limited scale.