Elizabeth Hegedus

Survivability of vancomycin resistant enterococci and fitness cost of vancomycin resistance acquisition

Aims: To investigate the survivability of vancomycin resistant enterococci (VRE) under dry starvation conditions and the fitness cost of vancomycin resistance. Methods: VRE colonies on cotton swabs were incubated at room temperature in a sterile box and cultured weekly until cultures no longer showed growth. Negative swabs inoculated into brain heart infusion (BHI) broth were subcultured to blood agar after 24, 48, and 72 hours of incubation to resuscitate viable but non-culturable cells. Stability of the vancomycin resistance determinant and of the DNA fingerprint pattern was determined by multiplex polymerase chain reaction (PCR) and repetitive PCR, respectively. Tests for fitness cost were carried out on the same VRE isolates and 28 hospital vancomycin sensitive enterococci (VSE) isolates by incubation and measurement of optical density using a microplate reader and comparing maximum growth rate and lag phase duration between VRE and VSE, using independent samples t tests. Results: Mean maximum time of recovery by primary culture was 8.5 weeks for Enterococcus faecalis VRE and 21.8 weeks for E faecium VRE. Two of two E faecalis isolates were resuscitated after 24 hours in BHI broth, and two of five E faecium isolates after 72 hours. No fitness cost of vancomycin resistance was demonstrated. Conclusions: VRE can survive for prolonged periods in a dry starvation state, retaining their genetic complement, including vancomycin resistance determinants, and show little or no fitness cost of vancomycin resistance. Thus, the rate of entry required for VRE to become, and remain, endemic in the community is relatively small.

Biofilm formation and esp gene carriage in enterococci

Aims: To investigate biofilm production and esp carriage in enterococci. Methods: Biofilm production in vancomycin resistant enterococci (VRE) and vancomycin susceptible enterococci (VSE) was tested on a microtitre plate method, using both brain heart infusion (BHI) broth and human serum as media. Isolates were screened for the esp gene, which has been reported to be essential for biofilm formation in enterococci, by means of the polymerase chain reaction. Results: None of seven VRE and nine of 28 VSE tested formed a biofilm. One initially negative VRE Enterococcus faecium isolate produced a strong biofilm after 21 weeks of dry starvation on a cotton swab. By Fisher’s exact test, there was no significant difference in biofilm formation between VRE and VSE, E faecalis and E faecium, or isolates from different sites. Biofilm formation was independent of possession of the esp gene. One isolate produced a strong biofilm in human serum but only a weak biofilm in BHI, whereas another produced a moderate biofilm in human serum but a weak biofilm in BHI. Conclusions: The acquisition of vancomycin resistance may result in a lower ability to form biofilms, but a larger study using clinical isolates is needed to test this hypothesis. That one initially negative VRE isolate produced a strong biofilm after prolonged dry starvation suggests that biofilm formation may be an adaptive response. The esp gene does not appear to be necessary or sufficient for production of biofilms in enterococci.

Selected culturable enteric bacterial populations are modified by diet acidification and the growth promotant Tylosin

Aims:  To determine the effect of diet acidification and an in‐feed antibiotic growth promotant (Tylosin, Ty) on selected culturable bacterial populations in the gastrointestinal tract (GIT) of mice.

The Effect of Dofetilide on the Heart Rate of GD11 and GD13 Rat Embryos, in vivo, Using Ultrasound.

BACKGROUND There are a wide range of drugs including antidepressants, anticonvulsants and antipsychotics that cause embryonic bradycardia in vitro but it is unknown if they have a similar effect in vivo. One way to verify whether these in vitro findings are replicated in vivo is by the use of ultrasound examination of dosed pregnant rats. We tested this by examining the effect of dofetilide on embryonic heart rate (HR) in vivo using ultrasound. METHODS Rats were dosed with dofetilide (4 or 2.5 mg/kg) on GD11 or (5 or 2.5 mg/kg) on GD13 and embryonic HR assessed by ultrasound, 2 and 24 hr later. Fetuses were examined for malformations on GD20. RESULTS HR of control rat embryos showed a wide range at each gestational day. Dosing with dofetilide on GD11 caused severe bradycardia (∼ 60% reduction) 2 hours after dosing with recovery after 24 h of >60% of LD but death and slow HR among the HD embryos. At term, 32% of the LD surviving fetuses had hypoplastic upper lip while >90% of HD embryos had died. On GD13, embryonic HR was reduced in a dose-dependent manner with >85% of LD and HD recovered by 24 hr. At term, all LD fetuses were normal while 29% of HD fetuses had limb defects. CONCLUSIONS Ultrasound is a useful technique to investigate the effect of maternally administered drugs on the embryonic HR in the rat. The results may provide more information about the safety of these drugs in pregnancy leading to better risk assessment for the human.

Counselling regarding paternal exposures: Can we do better?

MotherSafe is a free telephone‐based counselling service for the general public and healthcare providers concerned about exposures during pregnancy and breastfeeding. Calls relating to paternal exposures are less common, but can cause distress to the person concerned. This review seeks to identify the key concerns and what information is available to address these concerns.

Using the Jigsaw Method to Teach Abdominal Anatomy: Using the Jigsaw Method to Teach Anatomy

This study evaluates a cooperative learning approach for teaching anatomy to health science students incorporating small group and peer instruction based on the jigsaw method first described in the 1970s. Fifty‐three volunteers participated in abdominal anatomy workshops. Students were given time to become an “expert” in one of four segments of the topic (sub‐topics) by allocating groups to work‐stations with learning resources: axial computerized tomography (CT) of abdominal structures, axial CT of abdominal blood vessels, angiograms and venograms of abdominal blood vessels and structures located within abdominal quadrants. In the second part of workshop, students were redistributed into “jigsaw” learning groups with at least one “expert” at each workstation. The “jigsaw” learning groups then circulated between workstations learning all sub‐topics with the “expert” teaching others in their group. To assess abdominal anatomy knowledge, students completed a quiz pre‐ and post‐ workshop. Students increased their knowledge with significant improvements in quiz scores irrespective of prior exposure to lectures or practical classes related to the workshop topic. The evidence for long‐term retention of knowledge, assessed by comparing end‐semester examination performance of workshop participants with workshop nonparticipants, was less convincing. Workshop participants rated the jigsaw workshop highly for both educational value and enjoyment and felt the teaching approach would improve their course performance. The jigsaw method improved anatomy knowledge in the short‐term by engaging students in group work and peer‐led learning, with minimal supervision required. Reported outcomes suggest that cooperative learning approaches can lead to gains in student performance and motivation to learn. Anat Sci Educ 00: 000–000.