Reduction in the colonization of central venous cannulae by mupirocin

In an in-vitro simulation of an intravascular cannula enclosed in a fibrin sheath, 0.03 mg1(-1) of mupirocin prevented significant colonization [greater than 15 colony forming units (cfu)] by two clinical isolates of Staphylococcus epidermidis and one each of S. saprophyticus, S. hominis and S. haemolyticus. This suggests that in vivo, where protein binding of mupirocin is 95-97%, 1 mg 1(-1) of mupirocin at the cannula surface would be required to prevent colonization. These results support the findings of our previously published prospective controlled trial, in which mupirocin applied to the insertion sites of 172 internal jugular cannulae reduced the rate of colonization of cannula tips to 5%, compared with 25% for the 186 controls (P less than 0.001). Of the 46 colonized cannula tips from 110 control patients, the same species was isolated from the skin of the insertion site in 67% and from the lumen flush in only 15%. Analysed by patient, mupirocin reduced the proportion of patients with colonized tips from 17% to 3% after 24 h of infection, and from 35 to 10% after 48 h (P = 0.002). The use of agar containing charcoal, as a mupirocin neutralizer, and the incubation of tip-culture plates flooded with the Oxford staphylococcus, gave no evidence of carry over of mupirocin onto cannulae removed from mupirocin-treated patients

Minimal dose requirements for nasal mupirocin and its role in the control of epidemic MRSA

Staphylococci are still a leading cause of hospital infection. The success of nasal mupirocin for the control of epidemic methicillin- resistant Staphylococcus aureus (EMRSA), the prevention of colonization of central venous cannulae, and the prevention of septicaemia in haemodialysis patients should encourage the use of minimal dose regimens to minimize the emergence of mupirocin resistance. Mupirocin applied to the anterior nares 4-times daily usually eliminates S. aureus, including EMRSA, within 48 h. Elimination is sustained for several weeks in patients and staff. We recently found that a single dose, or a regimen of 4-times daily for 2 days, eliminated nasal carriage of S. aureus within 24 h; 7 days after a single dose, 92% of the subjects were still cleared; 7 days after the 2-day course, 96% remained free of nasal S. aureus. Ward personnel who are nasal carriers of EMRSA can, provided that other carriage sites are negative, return to work after 2 days of a 4-times daily intranasal regimen. The UK guidelines, recently published in this Journal, recommend an aggressive approach to identifying and eliminating EMRSA, including the elimination of nasal carriage. This approach is increasingly associated with the control of EMRSA in the UK and elsewhere

Mupirocin for the reduction of colonization of internal jugular cannulae: a randomized controlled trial

In a prospective study, 218 cardiothoracic patients, in whom 'Abbocath-T' cannulae had been inserted preoperatively into the internal jugular vein, were randomized to receive skin preparation of the insertion site with tincture of iodine (108 controls) or tincture of iodine followed by application of sterile 2% calcium mupirocin ointment (110 test patients). Cannulae were usually removed within 48 h of the operation. Patients receiving mupirocin were less likely to develop significant colonization of one or more of their cannulae as judged by Maki's criterion of a yield of greater than 15 colony forming units (cfu) from a cannula segment rolled on an agar plate (17% of mupirocin treated patients compared with 54% of the controls, P less than 0.001). Coagulase-negative staphylococci, micrococci, or both, were the commonest isolates and were cultured from 70% of the 186 control cannulae compared with 24% of 172 cannulae inserted through mupirocin-treated skin (P less than 0.001). A count of more than 15 cfu was found on the tips of 25% control cannulae compared with 5% of the cannulae from mupirocin-treated patients, an effect which was independent of in-situ time (P less than 0.001). For cannulae with colonized tips, the same species was isolated from the skin of the insertion site in 67%, from the exterior of the hub in 61% and from the lumen in only 15%. There were no side effects attributed to mupirocin or superinfection with resistant organisms. We conclude that in cardiothoracic patients the application of mupirocin after standard skin preparation with tincture of iodine significantly reduces the colonization of central venous cannulae by organisms derived from the skin insertion site

A genomic portrait of the emergence, evolution, and global spread of a methicillin-resistant staphylococcus aureus pandemic

The widespread use of antibiotics in association with high-density clinical care has driven the emergence of drug-resistant bacteria that are adapted to thrive in hospitalized patients. Of particular concern are globally disseminated methicillin-resistant Staphylococcus aureus (MRSA) clones that cause outbreaks and epidemics associated with health care. The most rapidly spreading and tenacious health-care-associated clone in Europe currently is EMRSA-15, which was first detected in the UK in the early 1990s and subsequently spread throughout Europe and beyond. Using phylogenomic methods to analyze the genome sequences for 193 S. aureus isolates, we were able to show that the current pandemic population of EMRSA-15 descends from a health-care-associated MRSA epidemic that spread throughout England in the 1980s, which had itself previously emerged from a primarily community-associated methicillin-sensitive population. The emergence of fluoroquinolone resistance in this EMRSA-15 subclone in the English Midlands during the mid-1980s appears to have played a key role in triggering pandemic spread, and occurred shortly after the first clinical trials of this drug. Genome-based coalescence analysis estimated that the population of this subclone over the last 20 yr has grown four times faster than its progenitor. Using comparative genomic analysis we identified the molecular genetic basis of 99.8% of the antimicrobial resistance phenotypes of the isolates, highlighting the potential of pathogen genome sequencing as a diagnostic tool. We document the genetic changes associated with adaptation to the hospital environment and with increasing drug resistance over time, and how MRSA evolution likely has been influenced by country-specific drug use regimens

Emergence of carbapenem-resistant Enterobacteriaceae in a UK paediatric hospital

Background Carbapenem-resistant Enterobacteriaceae are an emerging global infection threat. However, there are few data describing their clinical importance in children. Aim This retrospective study reviewed the prevalence and resistance mechanisms of carbapenem-resistant Enterobacteriaceae grown from clinical and surveillance samples in a large tertiary referral children's hospital in the UK. Methods Carbapenem-resistant Enterobacteriaceae were sought in specimens submitted for diagnostic and surveillance purposes at Alder Hey Children's NHS Foundation Trust, Liverpool, between September 2011 and August 2012. Mechanisms of resistance were identified using phenotypic and/or molecular methods. Variable number tandem repeat profiling was used to type carbapenemase-producing strains. Findings During the 12-month study period, carbapenem-resistant Enterobacteriaceae were recovered from 24 patients. Five isolates were from clinical diagnostic specimens whereas 19 of 421 patients had positive rectal surveillance swabs (4.5%). Of the 24 isolates, seven (all Klebsiella spp.) harboured carbapenemases: three had blaKPC and four blaNDM, whereas 17 had resistance due to combinations of AmpC or extended-spectrum ß-lactamase activity plus impermeability. Conclusion Carbapenem-resistant Enterobacteriaceae and, in particular, those with carbapenemases, are an emerging infection problem in a major paediatric hospital in the UK. Active surveillance is required to monitor and control their spread