Zeynep Senses

Acinetobacter septicus sp. nov. Association with a Nosocomial Outbreak of Bacteremia in a Neonatal Intensive Care Unit

ABSTRACT Acinetobacter species other than Acinetobacter baumannii have rarely been reported to be associated with nosocomial outbreaks of bloodstream infections. Within a period of 1 week, seven Acinetobacter-like isolates were recovered from peripheral blood and catheter specimens of five patients at a neonatal intensive care unit (NICU) in a tertiary hospital in Turkey. All five patients had placement of central venous catheters and had received total parenteral nutrition before the onset of bacteremia. Two of the five patients died. Medical devices, tap water, aerators, water samples, various surfaces, intravenous fluids, and the hands of health care workers in the NICU were sampled and were culture negative for the bacterium. All seven of the isolates had identical biochemical reactions, antimicrobial susceptibility results, and pulsed-field gel electrophoresis patterns, indicating a clonal nosocomial outbreak. A panel of standard biochemical reaction profiles and three phenotypic commercial identification systems failed to identify these isolates. Phenotypically, the isolate differed from Acinetobacter ursingii by its hemolysis on sheep blood agar and its negative citrate utilization. Sequences of the full 16S rRNA gene, which contained at least three different gene copies with polymorphic sequences between nucleotide positions 70 and 206, were determined from the first recovered isolate. The complete 1,529- to 1,531-bp 16S rRNA gene sequences and partial 801-bp rpoB gene sequences had similarities of 99.5% and 97.2%, respectively, to an A. ursingii isolate. The DNA-DNA similarities of the strain against the type strain of A. ursingii were 64.7 and 68.7%, which were lower than the recommended threshold value of 70% for the definition of bacterial species. These data indicate that a novel Acinetobacter organism caused the nosocomial outbreak of bacteremia in the NICU unit. We propose the designation of Acinetobacter septicus sp. nov. for these isolates, with isolate AK001 as the type strain.

Bacterial reduction by extensive versus conservative root canal instrumentation in vitro

Objective. This study aimed to test the hypothesis that aggressive dentin removal through greater-tapered instrumentation reduces the intracanal bacteria more effectively than conservative dimension instrumentation. Material and methods. Twenty extracted human lower premolar teeth were used. After extirpation of the pulps, the teeth were autoclaved and immersed in a broth inoculated with Enterococcus faecalis and incubated for 7 days to allow infection of the dentinal tubules. The teeth were divided into 2 experimental groups, each comprising 10 teeth. The teeth were instrumented either with ProTaper or with Hero Shaper nickel-titanium rotary instrumentation techniques. It was calculated that ProTaper theoretically has the potential to remove at least twice the dentin volume compared with Hero Shaper. The apical preparation was standardized to file size 30. Saline solution was used for irrigation. Bacteriological samples were taken before and after instrumentation and plated onto tryptic soy agar, and the reduction in numbers was calculated. Results. Both instrumentation techniques significantly reduced the number of bacteria in the root canal (p<0.05). Reduction in absolute bacterial numbers was up to 98%. There was no statistically significant difference between the two techniques. Conclusions. Preparation with an instrumentation technique removing substantial amounts of dentin did not reduce the intracanal bacteria more effectively than a more conservative instrumentation technique.

Platelet aggregation in children with Helicobacter pylori infection.

This study was performed to investigate the platelet aggregation alterations in platelet-rich plasma (PRP) samples of children with Helicobacter pylori (H pylori) infection. Platelet aggregation induced by adenosine diphosphate (ADP), collagen, ristocetin, or epinephrine was studied with photometric aggregometry in 30 patients before and after eradication therapy and in a control group including 15 children. The pretreatment mean maximum aggregation values and slope were significantly lower (P < .0001) in the study group at 10 μmol/L concentrations of ADP (ADP-like defect). The maximum aggregation values and slope revealed no significant differences (P > 0.05) between the study group after therapy and the control group. We concluded that H pylori infection may cause dysfunction of platelets in children and can be reversed by H pylori eradication therapy. Further studies should be carried out to determine the mechanisms of platelet dysfunction in children with H pylori infection.

Reduction in co-trimoxazole resistance inEscherichia coli isolates from urinary tract infections between 1995 and 2005: a multicenter study in Ankara, Turkey

Co-trimoxazole resistance inEscherichia coli isolates from urinary tract infections (UTI) was assessed in 382 strains from 1995 and 510 strains from 2005. The strains were collected from five microbiology laboratories in Ankara, Turkey. Documentation on patient gender, age and outpatient/inpatient status was collected in 2005, but not in 1995. The resistance percentages were 751% in 1995 and 55.5% in 2005. This reduction in resistance percentage was statistically significant, overall in all except two of the participating laboratories. The resistance percentage in 2005 was 61.1% for children (n=208) and 51.2% for adults (n=258), 53.7% for females (n=380) and 60.8% for males (n=130), and 55.3% for outpatients (n=400) and 56.4% for inpatients (n=110). The reduction in resistance is believed to be a consequence of reduced usage. Although decreased, the level of co-trimoxazole resistance remains high, and continued avoidance of its use for empiric treatment of UTI in Turkey appears to be an appropriate strategy.