The relationship of a clonal outbreak of Enterococcus faecium vanA to methicillin-resistant Staphylococcus aureus incidence in an Australian hospital

Australian isolates of vancomycin-resistant enterococci (VRE) have been widely scattered geographically, predominantly polyclonal and of the VanB phenotype. Forty-nine VRE were isolated from 47 patients in our hospital from October 1996 to December 1999. Forty-four of these VRE were Enterococcus faecium with a vanA glycopeptide resistance genotype. Four isolates were pathogenic. Thirty-five VRE were from an outbreak in the Renal and Infectious Diseases Units over a four-month period. Pulsed-field gel electrophoresis (PFGE) demonstrated that 41 of the 49 VRE were indistinguishable or closely related. Enhanced environmental cleaning, strict contact isolation of colonized patients and reducing inpatient admissions terminated the epidemic. Cohorting of methicillin-resistant Staphylococcus aureus (MRSA)-positive patients was restricted because VPE patients occupied the isolation facilities. This resulted in a statistically significant increase in MRSA infections across the hospital. VRE epidemics have the ability to influence the epidemiology of other nosocomial pathogens when infection control resources are exhausted. (C) 2001 The Hospital Infection Society.

Post-antibiotic growth suppression of linezolid against Gram-positive bacteria

The in vitro post-antibiotic effects (PAEs) of eight different concentrations of linezolid against Gram-positive cocci were investigated and the results analysed using the sigmoid E-max model for mathematically modelling the PAE. Mean maximal linezolid PAEs against strains of Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, Enterococcus faecium and Streptococcus pneumoniae were 2.2, 1.8, 2.8, 2.0 and 3.0 h, respectively. Resistance to methicillin (for the staphylococci), vancomycin (for the enterococci) and penicillin (for the pneumococci) had no effect on the duration of the PAE. Results of PAE testing support twice-daily dosing of linezolid in humans.

Lactobacillus ruminis is a predominant lactic acid producing bacterium in the caecum and rectum of the pig

Aims: To identify the predominant lactic acid producing bacteria in the small intestine, caecum and the rectum of the healthy pig. Methods and Results: Samples obtained from the large intestine of healthy pigs post-mortem were cultured using a modified agar-MRS medium in roll tubes. Thirteen isolates were selected on the basis of their morphological characteristics and Gram stain reaction for gene sequencing. These isolates were characterized by DNA sequence analysis of 16S rDNA. Eight isolates were identified as Lactobacillus ruminis , two as Enterococcus faecium , one as Mitsuokella multiacidus and two as Escherichia coli . Conclusion: This is the first report of Lact. ruminis as the dominant lactic acid bacteria in the large intestine of the pig. Significance and Impact of the Study: The results suggest that Lact. ruminis is a dominant bacterium in the large intestine of the healthy pig. Future work should focus on the role of this bacterium in relation to the physiological function of the intestine and the health of the animal.