Multidrug-resistant bacteria colonization amongst patients newly admitted to a geriatric unit: a prospective cohort study

OBJECTIVES

To determine prevalence, incidence and risk factors of colonization by extended-spectrum β-lactamase-producing Enterobacteriacae (ESBLE), methicillin-resistant Staphylococcus aureus (MRSA), and vancomycin-resistant Enterococcus (VRE) in aged subjects admitted to an acute geriatric unit at a teaching hospital.

METHODS

During 12 months, 337 patients were screened by nasal, oropharyngeal, groin, axillary and rectal swabs upon admission and at discharge.

RESULTS

The prevalence of ESBLE, MRSA and VRE carriage upon admission was 11.6%, 7.5% and 0.6%, respectively. The incidence density of ESBLE and MRSA carriage was respectively of 1.77 and 2.40 new cases for 1000 patient-days. No cases of VRE acquisition were found. Risk factors for ESBLE colonization on admission were: multiple contacts with the hospital within the previous year, chronic catheter use and a high level of dependency. For MRSA, risk factors were: chronic wounds, anti-acid use and a high level of dependency.

CONCLUSION

This study shows a high prevalence of asymptomatic colonization of ESBL-producing Escherichia coli in patients admitted to an acute geriatric ward, as high as MRSA carriage. A low functional status is a common risk factor both for ESBLE and for MRSA colonization and it highlights the need to reinforce infection control measures.

Extended-Spectrum Beta-Lactamases Producing E. coli in Wildlife, yet Another Form of Environmental Pollution?

Wildlife is normally not exposed to clinically used antimicrobial agents but can acquire antimicrobial resistant bacteria through contact with humans, domesticated animals and the environment, where water polluted with feces seems to be the most important vector. Escherichia coli, an ubiquitous commensal bacterial species colonizing the intestinal tract of mammals and birds, is also found in the environment. Extended-spectrum beta-lactamases producing E. coli (ESBL-E. coli) represent a major problem in human and veterinary medicine, particular in nosocomial infections. Additionally an onset of community-acquired ESBL-E. coli infections and an emergence in livestock farming has been observed in recent years, suggesting a successful transmission as well as persistence of ESBL-E. coli strains outside clinical settings. Another parallel worldwide phenomenon is the spread of ESBL-E. coli into the environment beyond human and domesticated animal populations, and this seems to be directly influenced by antibiotic practice. This might be a collateral consequence of the community-onset of ESBL-E. coli infections but can result (a) in a subsequent colonization of wild animal populations which can turn into an infectious source or even a reservoir of ESBL-E. coli, (b) in a contribution of wildlife to the spread and transmission of ESBL-E. coli into fragile environmental niches, (c) in new putative infection cycles between wildlife, domesticated animals and humans, and (d) in problems in the medical treatment of wildlife. This review aims to summarize the current knowledge on ESBL-E. coli in wildlife, in turn underlining the need for more large scale investigations, in particular sentinel studies to monitor the impact of multiresistant bacteria on wildlife.

Cross-sectional study of antimicrobial-resistant bacteria in horses. Part 1: Prevalence of antimicrobial-resistant Escherichia coli and methicillin-resistant Staphylococcus aureus

REASONS FOR PERFORMING STUDY

The increasing prevalence of antimicrobial-resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA) and antimicrobial-resistant Escherichia coli represents a significant problem. However, the carriage of such bacteria by horses in the UK has not been well characterised.

OBJECTIVES

To estimate the prevalence of nasal carriage of MRSA and faecal carriage of antimicrobial-resistant E. coli amongst horses in the general equine community of the mainland UK.

METHODS

A cross-sectional study of horses recruited by 65 randomly selected equine veterinary practices was conducted, with nasal swabs and faecal samples collected. Faecal samples were cultured for antimicrobial-resistant E. coli. Nasal swabs were cultured for staphylococcal species; methicillin-resistant isolates identified as S. aureus were characterised by SCCmec and spa gene typing. Multilevel logistic regression models were used to calculate prevalence estimates with adjustment for clustering at practice and premises levels. Spatial variation in risk of antimicrobial resistance was also examined.

RESULTS

In total, 650 faecal samples and 678 nasal swabs were collected from 692 horses located on 525 premises. The prevalence of faecal carriage of E. coli with resistance to any antimicrobial was 69.5% (95% CI 65.9-73.1%) and the prevalence of extended-spectrum β-lactamase (ESBL)-producing E. coli was 6.3% (95% CI 4.1-9.6%). The prevalence of nasal carriage of MRSA was 0.6% (95% CI 0.2-1.5%). Spatial analysis indicated variation across the UK for risk of carriage of resistant and multidrug-resistant (resistant to more than 3 antimicrobial classes) E. coli.

CONCLUSIONS AND POTENTIAL RELEVANCE

Carriage of MRSA by horses in the community appears rare, but the prevalence of antimicrobial-resistant E. coli (including ESBL-producing E. coli) is higher. A high prevalence of antimicrobial-resistant bacteria could have significant health implications for the horse population of the UK.

Complete sequence and molecular epidemiology of IncK epidemic plasmid encoding blaCTX-M-14

This plasmid is disseminated worldwide in Escherichia coli isolated from humans and animals.

Antimicrobial drug resistance is a global challenge for the 21st century with the emergence of resistant bacterial strains worldwide. Transferable resistance to β-lactam antimicrobial drugs, mediated by production of extended-spectrum β-lactamases (ESBLs), is of particular concern. In 2004, an ESBL-carrying IncK plasmid (pCT) was isolated from cattle in the United Kingdom. The sequence was a 93,629-bp plasmid encoding a single antimicrobial drug resistance gene, bla_CTX-M-14. From this information, PCRs identifying novel features of pCT were designed and applied to isolates from several countries, showing that the plasmid has disseminated worldwide in bacteria from humans and animals. Complete DNA sequences can be used as a platform to develop rapid epidemiologic tools to identify and trace the spread of plasmids in clinically relevant pathogens, thus facilitating a better understanding of their distribution and ability to transfer between bacteria of humans and animals.

Methicillin-resistant Staphylococcus aureus: the European landscape

Pan-European surveillance of bacteraemia caused by methicillin-resistant Staphylococcus aureus (MRSA) shows it to be a problem affecting all European countries, although there is marked geographical variation in prevalence. Although the proportion of S. aureus bacteraemia due to MRSA is declining in many countries, data from the European Antimicrobial Resistance Surveillance System (EARSS) for 2008 showed that in more than one-third of countries the proportion remained >25%. In contrast to bacteraemia, community-associated MRSA infection in Europe remains relatively uncommon. However, there appears to be an increasing problem involving transmission of MRSA (particularly sequence type 398) from colonized livestock, particularly pigs, to farm workers, abattoir workers and veterinarians who are in contact with such animals. Molecular analysis of isolates of MRSA has shown that there has been spread of only a limited number of MRSA clones in Europe and that many of these clones show geographical clustering due to dissemination through regional healthcare networks. Despite our increasing understanding of the epidemiology of MRSA in Europe, MRSA infections continue to pose a significant public health challenge.