Topical mupirocin for eradication of MRSA colonization with mupirocin-resistant strains

Management of healthcare-associated methicillin-resistantStaphylococcus aureus

Healthcare-associated methicillin-resistant Staphylococcus aureus is a major cause of nosocomial infections worldwide, with significant attributable morbidity and mortality in addition to pronounced healthcare costs. Treatment results with vancomycin--the current recommended antibiotic for serious methicillin-resistant S. aureus infections--have not been impressive. The recent availability of effective antimicrobial agents other than glycopeptides, such as linezolid and daptomycin, as well as the anticipated approval of newer agents with diverse mechanisms of action, has somewhat ameliorated the threat posed by this organism. However, these drugs are expensive, and there is still no overall satisfactory strategy for reducing the incidence of healthcare-associated methicillin-resistant S. aureus in endemic regions. Although early results with the Society for Healthcare Epidemiology of America guidelines give cause for cautious optimism, long-term experience is lacking, and it is likely that these guidelines will have to be adapted according to local conditions and resources before implementation. Trends to keep in mind when considering the problem of healthcare-associated methicillin-resistant S. aureus include the advent of community-associated methicillin-resistant S. aureus, and the propensity of S. aureus to evolve and acquire resistance determinants over time. This was last vividly demonstrated by the handful of vancomycin-resistant S. aureus isolated recently, which had acquired the vancomycin resistance gene from vancomycin-resistant enterococci.

Antibiotic overuse and resistance in dermatology

Antibiotics have a significant role in dermatology, treating a wide range of diseases, including acne, rosacea, inflammatory skin conditions and skin structure infections, such as cellulitis, folliculitis, carbuncles, and furuncles. Because of their consistent use, utility, and availability, antibiotics are susceptible to overuse within the medical practice, and, specific to this discussion, in the dermatologic setting. The issue of continuously increasing risk of antibiotic resistance remains an important concern to the dermatologist. The scope of this review will be to provide an overview of the common antibiotics used in the dermatologic setting with an emphasis on identifying areas of overuse, reported bacterial resistance, and discussion of clinical management aimed at decreasing antibiotic resistance.

Antibiotic Treatment of Multidrug-Resistant Organisms in Cystic Fibrosis

Respiratory tract infection with eventual respiratory failure is the major cause of morbidity and mortality in cystic fibrosis (CF). Infective exacerbations need to be treated promptly and effectively to minimize potentially accelerated attrition of lung function. The choice of antibiotic depends on in vitro sensitivity patterns. However, physicians treating patients with CF are increasingly faced with infection with multidrug-resistant isolates of Pseudomonas aeruginosa. In addition, innately resistant organisms such as Burkholderia cepacia complex, Stenotrophomonas maltophilia and Achromobacter (Alcaligenes) xylosoxidans are becoming more prevalent. Infection with methicillin-resistant Staphylococcus aureus (MRSA) is also a problem. These changing patterns probably result from greater patient longevity and increased antibiotic use for acute exacerbations and maintenance care. Multidrug-resistant P. aeruginosa infection may be treated successfully by using two antibiotics with different mechanisms of action. In practice antibiotic choices have usually been made on a best-guess basis, but recent research suggests that more directed therapy can be achieved through the application of multiple-combination bactericidal testing (MCBT). Aerosol delivery of tobramycin for inhalation solution achieves high endobronchial concentrations that may overcome bacterial resistance as defined by standard laboratory protocols. Resistance to colistin is rare and this antibiotic should be seen as a valuable second-line drug to be reserved for multidrug-resistant P. aeruginosa. The efficacy of new antibiotic groups such as the macrolides needs to be evaluated.CF units should adopt strict segregation policies to interrupt person-to-person spread of B. cepacia complex. Treatment of panresistant strains is difficult and often arbitrary. Combination antibiotic therapy is recommended, usually tobramycin and high-dose meropenem and/or ceftazidime, but the choice of treatment regimen should always be guided by the clinical response.The clinical significance of S. maltophilia, A. xylosoxidans and MRSA infection in CF lung disease remains uncertain. If patients show clinical decline and are chronically colonized/infected with either of the former two pathogens, treatment is recommended but efficacy data are lacking. There are defined microbiological reasons for attempting eradication of MRSA but there are no proven deleterious effects of this infection on lung function in patients with CF. Various treatment protocols exist but none has been subject to a randomized, controlled trial. Multidrug-resistant microorganisms are an important and growing issue in the care of patients with CF. Each patient infected with such strains should be assessed individually and antibiotic treatment planned according to in vitro sensitivity, patient drug tolerance, and results of in vitro studies which may direct the physician to antibiotic combinations most likely to succeed.

A double-blind, randomized, controlled trial of topical polysporin triple compound versus topical mupirocin for the eradication of colonization with methicillin-resistant Staphylococcus aureus in a complex continuing care population

BACKGROUND

Intranasal mupirocin or Polysporin Triple (PT) ointment (polymyxin B, bacitracin, gramicidin), in combination with chlorhexidine body washes, have been used for eradicating methicillin-resistant Staphylococcus aureus (MRSA), but no comparative studies have been done.

METHODS

A double-blind, randomized, controlled clinical trial to compare the efficacy of mupirocin versus PT ointment in combination with chlorhexidine body washes in eradicating MRSA carriage was conducted. Asymptomatic MRSA carriers, medically stable and at least 18 years of age who were patients on medical wards, received twice daily application of either mupirocin or PT ointment to the anterior nares plus once daily 2% chlorhexidine body washes for seven days. Follow-up swabs from multiple sites using broth enrichment were conducted at 48 h, and one, two, four, eight and 12 weeks.

RESULTS

Of 103 patients eligible for analysis (54 mupirocin; 49 PT), no significant differences between the two groups with respect to baseline demographics, risk factors for MRSA or MRSA colonization sites were noted. At 48 h, 35 of 54 (65%) patients in the mupirocin group versus 15 of 49 (31%) in the PT group (P=0.001) were found to be MRSA negative at all sites. Significant differences were observed at one and two weeks but were not maintained at other intervals. In those with complete microbiological follow-up, MRSA eradication at all sites occurred in 12 of 39 (30.8%) mupirocin- and one of 36 (2.8%) PT-treated patients (P=0.001).

CONCLUSION

Both agents demonstrated poor efficacy and PT was significantly less efficacious than mupirocin at 12 weeks in eradicating MRSA from all sites.

Methicillin-resistant Staphylococcus aureus in Canada: a historical perspective and lessons learned

The history of methicillin-resistant Staphylococcus aureus (MRSA) in Canada has many similarities to MRSA evolution worldwide, but especially to that in the United States and United Kingdom. Reports of MRSA occurred as early as 1964, and community isolates were cited in the 1970s. Nosocomial outbreaks were becoming common by 1978 and flourished gradually thereafter. Endemic institutional MRSA became predominant in the 1990s, threatening large teaching hospitals in particular. In the last decade, both hospital-acquired and community-acquired MRSA have created major medical problems in Canada. More recently, an epidemic of Canadian community-acquired MRSA-10, has led to heightened public health concerns. Canadian contributions to MRSA science are numerous, with organized surveillance continuing to mature across the nation. A typing system for epidemic clones is now available and is being judiciously applied. Estimated costs for MRSA surveillance, treatment, and control are extraordinary, paralleling the dramatic rise in the number of MRSA isolations. Whereas surveillance continues to form an essential aspect of MRSA management, control, eradication, and overall diminution, MRSA reservoirs deserve much greater attention. Such efforts, however, must be as widely publicized in the community and in patient homes as they are in medical institutions responsible for both acute and long-term care.

Mupirocin resistance among methicillin-resistant Staphylococcus aureus-colonized patients at admission to a tertiary care medical center

All patients admitted to our tertiary care hospital from 1 December 2007 to 10 June 2008 were screened for methicillin (meticillin)-resistant Staphylococcus aureus (MRSA) nasal colonization, and the isolates were tested for mupirocin susceptibility by using Etest. Mupirocin resistance (MR) was noted to occur in 3.4% of MRSA carriers, and high-level MR was noted to occur in 0.62% of carriers.

Retapamulin: a review of its use in the management of impetigo and other uncomplicated superficial skin infections

Topical retapamulin (Altabax, Altargo) is the first pleuromutilin antibacterial approved for the treatment of uncomplicated superficial skin infections caused by Staphylococcus aureus (excluding meticillin-resistant S. aureus [MRSA]) and Streptococcus pyogenes in patients aged > or = 9 months. In the EU, retapamulin is indicated for use in patients with impetigo or with infected small lacerations, abrasions or sutured wounds (without abscesses); in the US, it is indicated for use in patients with impetigo. Retapamulin has a novel site of action on bacterial ribosomes. In clinical trials in patients with impetigo, topical retapamulin 1% ointment twice daily for 5 days (the approved regimen) was superior to placebo; treatment with retapamulin was noninferior to that with topical fusidic acid. In patients with secondarily infected traumatic lesions, treatment with retapamulin was noninferior to that with oral cefalexin, although the efficacy of retapamulin was reduced in patients with MRSA infections or superficial abscesses. Retapamulin was well tolerated in both paediatric and adult patients, and the majority of adverse events were of mild to moderate severity. Thus, the introduction of topical retapamulin 1% ointment extends the treatment options available in the management of impetigo and uncomplicated secondarily infected traumatic lesions.

Aminoacyl-tRNA synthetases: essential and still promising targets for new anti-infective agents

The emergence of resistance to existing antibiotics demands the development of novel antimicrobial agents directed against novel targets. Historically, bacterial cell wall synthesis, protein, and DNA and RNA synthesis have been major targets of very successful classes of antibiotics such as beta-lactams, glycopeptides, macrolides, aminoglycosides, tetracyclines, rifampicins and quinolones. Recently, efforts have been made to develop novel agents against validated targets in these pathways but also against new, previously unexploited targets. The era of genomics has provided insights into novel targets in microbial pathogens. Among the less exploited--but still promising--targets is the family of 20 aminoacyl-tRNA synthetases (aaRSs), which are essential for protein synthesis. These targets have been validated in nature as aaRS inhibition has been shown as the specific mode of action for many natural antimicrobial agents synthesized by bacteria and fungi. Therefore, aaRSs have the potential to be targeted by novel agents either from synthetic or natural sources to yield specific and selective anti-infectives. Numerous high-throughput screening programs aimed at identifying aaRS inhibitors have been performed over the last 20 years. A large number of promising lead compounds have been identified but only a few agents have moved forward into clinical development. This review provides an update on the present strategies to develop novel aaRS inhibitors as anti-infective drugs.

Community-acquired methicillin-resistant Staphylococcus aureus skin infections: a review of epidemiology, clinical features, management, and prevention

Community-acquired methicillin-resistant Staphylococcus aureus (CAMRSA) infection is a global problem of epidemic proportions. Many of the patients who develop CAMRSA skin lesions do not have infection-associated risk factors. Abscess, abscess with accompanying cellulitis, and cellulitis are the most common presentations of cutaneous CAMRSA infection; occasionally, these CARMSA-related lesions are misinterpreted as spider or insect bites. Other manifestations of cutaneous CAMRSA infection include impetigo, folliculitis, and acute paronychia. The management of CAMRSA skin infection includes incision and drainage, systemic antimicrobial therapy, and adjuvant topical antibacterial treatment. In addition, at the initial visit, bacterial culture of the lesion should be considered. Direct skin-to-skin contact, damage to the skin surface, sharing of personal items, and a humid environment are potential mechanisms for the acquisition and transmission of cutaneous CAMRSA infection. Measures that strive to eliminate these causes are useful for preventing the spread of CAMRSA skin infection.

Transient loss of high-level mupirocin resistance in Staphylococcus aureus due to MupA polymorphism

Spontaneous loss of MupA-mediated high-level mupirocin resistance was observed in Staphylococcus aureus, although the isolate gave a PCR-positive test result for mupA. Sequencing of the mupA gene identified a single base-pair deletion that resulted in a frameshift mutation and loss of functional protein. Reversion to the wild-type allele and restoration of high-level resistance occurred with high frequency (>10(-6)), indicating the transient nature of MupA polymorphism.

Randomized clinical trial of the effect of applying ointment to surgical wounds before occlusive dressing

BACKGROUND

A blinded randomized clinical trial was undertaken to evaluate the effect of applying ointment to a wound before occlusive dressing, in comparison with no ointment or sterile paraffin.

METHODS

Some 778 patients with 1801 surgical wounds following excision of skin lesions were enrolled in the trial. No ointment was placed on 510 sutured wounds of 247 patients, paraffin ointment was put on 729 wounds (269 patients) and mupirocin ointment on 562 wounds (262 patients). Wound infection, scar, haemorrhage, dehiscence and other complications were assessed at suture removal. At 6-9 months after surgery, patients were surveyed to assess the wounds, with a response rate of 74.0 per cent.

RESULTS

There were no significant differences in outcome for all endpoints evaluated. The infection rate was 1.4 per cent with no ointment, 1.6 per cent for paraffin and 2.3 per cent for mupirocin (P = 0.490). Total complication rates were 3.5, 4.7 and 4.8 per cent for no ointment, paraffin and mupirocin respectively (P = 0.590). Some 10.9, 10.3 and 8.2 per cent of patients respectively had a neutral or negative perception of their wounds at 6-9 months after surgery (P = 0.650). There was no difference in postoperative pain, degree of inconvenience or overall level of satisfaction with treatment.

CONCLUSION

Putting ointment on a surgical wound before occlusive dressing does not benefit the patient. In view of the risk of antibiotic resistance, mupirocin ointment is not indicated for clean surgical wounds.

Guidelines for the prophylaxis and treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections in the UK

These evidence-based guidelines have been produced after a literature review of the treatment and prophylaxis of methicillin-resistant Staphylococcus aureus (MRSA) infection. The guidelines were further informed by antibiotic susceptibility data on MRSA from the UK. Recommendations are given for the treatment of common infections caused by MRSA, elimination of MRSA from carriage sites and prophylaxis of surgical site infection. There are several antibiotics currently available that are suitable for use in the management of this problem and potentially useful new agents are continuing to emerge.

Mode of action and biochemical characterization of REP8839, a novel inhibitor of methionyl-tRNA synthetase

Aminoacyl-tRNA synthetases have attracted interest as essential and novel targets involved in bacterial protein synthesis. REP8839 is a potent inhibitor of MetS, the methionyl-tRNA synthetase in Staphylococcus aureus, including methicillin-resistant S. aureus (MRSA), and in Streptococcus pyogenes. The biochemical activity of REP8839 was shown by specific inhibition of purified S. aureus MetS (50% inhibitory concentration, <1.9 nM). Target specificity was confirmed by overexpression of the metS gene in S. aureus, resulting in an eightfold increase in the MIC for REP8839. Macromolecular synthesis assays in the presence of REP8839 demonstrated a dose-dependent inhibition of protein synthesis and RNA synthesis in S. pneumoniae R6, but only protein synthesis was affected in an isogenic rel mutant deficient in the stringent response. Strains with reduced susceptibility to REP8839 were generated by selection of strains with spontaneous mutations and through serial passages. Point mutations within the metS gene were mapped, leading to a total of 23 different amino acid substitutions within MetS that were located around the modeled active site. The most frequent MetS mutations were I57N, leading to a shift in the MIC from 0.06 microg/ml to 4 microg/ml, and G54S, resulting in a MIC of 32 microg/ml that was associated with a reduced growth rate. The mutation prevention concentration was 32 microg/ml in four S. aureus strains (methicillin-sensitive S. aureus and MRSA), which is well below the drug concentration of 2% (20,000 microg/ml) in a topical formulation. In conclusion, we demonstrate by biochemical, physiologic, and genetic mode-of-action studies that REP8839 exerts its antibacterial activity through specific inhibition of MetS, a novel target.

Cutaneous Community-acquired Methicillin-resistant Staphylococcus aureus Infection in Participants of Athletic Activities

OBJECTIVES

Cutaneous community-acquired methicillin-resistant Staphylococcus aureus (CAMRSA) has been identified in otherwise healthy individuals either with or without methicillin-resistant S. aureus (MRSA)-associated risk factors who participate in athletic activities. The purpose of this study was to describe the clinical features of CAMRSA skin infection that occurred in university student athletes, evaluate the potential mechanisms for the transmission of MRSA infection of the skin in participants of athletic activities, and review the measures for preventing the spread of cutaneous CAMRSA infection in athletes.

METHODS

A retrospective chart review of the student athletes from the University of Houston whose skin lesions were evaluated at the Health Center and grew MRSA was performed. The clinical characteristics and the postulated mechanisms of cutaneous MRSA infection in the athletes were compared with those previously published in reports of CAMRSA skin infection outbreaks in other sports participants.

RESULTS

Cutaneous CAMRSA infection occurred in seven student athletes (four women and three men) who were either weight lifters (three students) or members of a varsity sports team: volleyball (two women), basketball (one woman), and football (one man). The MRSA skin infection presented as solitary or multiple, tender, erythematous, fluctuant abscesses with surrounding cellulitis. The lesions were most frequently located in the axillary region (three weight lifters), on the buttocks (two women), or on the thighs (two women). The drainage from all of the skin lesions grew MRSA, which was susceptible to clindamycin, gentamicin, rifampin, trimethoprim/sulfamethoxazole, and vancomycin; five of the isolates were also susceptible to ciprofloxacin and levofloxacin. All of the bacterial strains were resistant to erythromycin, oxacillin, and penicillin. The cutaneous MRSA infections persisted or worsened in the six athletes who were empirically treated for methicillin-sensitive S. aureus at their initial visit. Complete resolution of the skin infection occurred after the abscesses had been drained and the athlete had been treated with systemic antimicrobial therapy for which the bacterial strain was susceptible.

CONCLUSIONS

Cutaneous CAMRSA infection typically presents as an abscess, with or without surrounding cellulitis, in otherwise healthy participants of athletic activities who have or do not have MRSA-associated risk factors. Athletes who have MRSA skin infections include weight lifters and team members from competitive sports such as basketball, fencing, football, rugby, volleyball, and wrestling. Bacterial culture of suspected infectious skin lesions should be performed to establish the diagnosis of cutaneous MRSA infection and to determine the antibiotic susceptibility of the bacterial isolate. Treatment of cutaneous MRSA infection involves drainage of the abscess (either spontaneously or after incision) and appropriate systemic antimicrobial therapy. Direct skin-to-skin physical contact with infectious lesions or drainage, skin damage that facilitates the entry of bacteria, and sharing of infected equipment, clothing, or personal items may result in the acquisition and transmission of MRSA infection in participants of athletic activities. Earlier detection and topical treatment of the athlete's skin wounds by their coaches, avoidance of contact with other participants' cutaneous lesions and their drainage, and good personal hygiene are measures that can potentially prevent the spread of cutaneous MRSA infection in participants of athletic activities.

Community-acquired methicillin-resistant Staphylococcus aureus: skin infection presenting as an axillary abscess with cellulitis in a college athlete

A healthy 19-year-old black man without any methicillin-resistant Staphylococcus aureus risk factors developed axillary boils after he began lifting weights at the university gym in Houston, TX. He presented with a large tender erythematous fluctuant abscess of his right axillae and a superiorly located smaller painful red indurated nodule; the surrounding cellulitis extended into the adjacent tissue (Figure). The abscess was incised, drained, and cultured. Empiric treatment with cephalexin 500 mg q.i.d. was given for 7 days. The culture grew methicillin-resistant S. aureus. Susceptibility testing of the S. aureus isolate was performed by Laboratory Corp. of America (Houston, TX); the Vitek system (Biomerieux, Hazelwood, MO) was used, and the specimen was incubated for 8 hours. Confirmation of methicillin resistance was performed using a methicillin-resistant S. aureus plate and the specimen was incubated for 24 hours. In addition to resistance to methicillin, the bacterial isolate was also resistant to ciprofloxacin, erythromycin, and penicillin. The S. aureus strain had intermediate susceptibility to levofloxacin and was susceptible to clindamycin, gentamicin, rifampin, tetracycline, trimethoprim/sulfamethoxazole, and vancomycin. The infection persisted and the antibiotic was changed to double strength trimethoprim/sulfamethoxazole, taken twice daily for 15 days. In addition, topical care included lesional and intranasal application of mupirocin 2% ointment and daily cleaning of the area with 10% povidone-iodine liquid soap. The skin infection completely resolved without recurrence within 2 weeks.

Routine use of mupirocin at the peritoneal catheter exit site and mupirocin resistance: still low after 7 years

OBJECTIVE

The purpose of this study (the third in a series of similar studies) is to evaluate the prevalence of Staphylococcus aureus (SA), methicillin-resistant SA (MRSA) and mupirocin-resistant SA (MuRSA) carriers in a peritoneal dialysis centre where patients have been instructed to use prophylactic mupirocin ointment at the catheter exit site over the last 7 years.

METHODS

Swabs were taken from catheter exit site, nares, axillae and groin in 147 chronic peritoneal dialysis out-patients between November 2003 and January 2004. Axillae/groin and nasal samples were pooled and cultured in the same medium, whereas exit site swabs were cultured separately. All SA isolated were tested for methicillin and mupirocin resistance using oxacillin screening plates and E-test strips.

RESULTS

Sixteen of 147 patients (10.9%) were found to be SA carriers: of these 13 (8.8%) had a positive nasal/axillae/groin culture; two (1.4%) had both nasal/axillae/groin- and exit site-positive culture; and one (0.7%) had only exit site-positive culture. In these 16 SA carriers, we found mupirocin-resistant strains (MuRSA) in four patients (25%) and MRSA in two patients (12.5%). Among the four MuRSA carriers, one had both nasal/axillae/groin- and exit site-positive culture and three had only nasal/axillae/groin-positive culture. Three high-level resistance and one low-level resistance MuRSA carriers were isolated. One MuRSA strain was also methicillin resistant. All MRSA strains were sensitive to vancomycin and rifampicin.

CONCLUSION

After 7 years' routine use of prophylactic mupirocin ointment at the catheter exit site in non-selected chronic peritoneal dialysis patients, MuRSA was found in 25% of SA strains isolated or in 2.7% of the patients. Compared with our previous study, 3 years earlier, there is no significant increase in the MuRSA prevalence in peritoneal dialysis patients who routinely apply mupirocin ointment at the catheter exit site.

Methicillin-resistant Staphylococcus aureus: impact on dermatology practice

Methicillin (meticillin)-resistant Staphylococcus aureus (MRSA) emerged in the 1960s and is now commonly seen in hospitals, clinics and, since the mid-1990s, the community. Risk factors for the acquisition of MRSA include chronic dermatoses, underlying medical illnesses, attending healthcare facilities, use of prescription antibacterials, surgery, intravenous lines, hospitalization in an intensive care unit, and proximity to patients colonized with MRSA. Recent community-associated strains often occur in patients without these risk factors. Staphylococci are readily spread from person to person and readily contaminate the environment. Infection control measures thus involve identifying the infected patients, separating them from other non-infected patients, cleaning of the environment and, most important of all, scrupulous attention to hand hygiene. Alcoholic antiseptic hand rubs offer an alternative to antiseptic hand washes and increase compliance. Treatment of MRSA skin infections is challenging. Topical agents such as mupirocin or fusidic acid can be used, but the organisms often become resistant. Systemic therapy involves non-beta-lactams. Parenteral treatment is generally with glycopeptides such as vancomycin; oral therapy is more complex. Monotherapy with quinolones, rifampin (rifampicin), and fusidic acid often results in the development of resistance and so, if any of these agents are chosen it should be in combination. There are no data on combination therapy, although rifampin-containing combinations are often chosen. Fourth-generation quinolones and linezolid are expensive but promising alternatives.

Methicillin-resistant Staphylococcus aureus whole-body decolonization among hospitalized patients with variable site colonization by using mupirocin in combination with octenidine dihydrochloride

The object of this study was to investigate the efficacy of a methicillin-resistant Staphylococcus aureus (MRSA) multisite carriage decolonization in 32 hospitalized carriers--25 from surgical and seven from medical wards. Twenty-four of the patients had wounds (e.g. chronic ulcers, surgical sites) and 17 were spinal cord injury patients. Decolonization was performed by intranasal application of mupirocin, combined with an octenidine dihydrochloride bodywash over a period of five days. Samples from the nose, forehead, neck, axilla and groin were taken 24-48 h before beginning decolonization (sample point I, N=32) and 24-48 h afterwards (sample point II, N=32). Further samples, were taken seven to nine days after the procedure (sample point III, N=25). Contact sheep blood agar plates (24 cm2) were used to quantify MRSA colonies on forehead and neck. MRSA from other sample sites was determined semi-quantitatively. All patients were proven to be MRSA positive at one or more extranasal site(s); 18.8% did not have nasal carriage. The overall decolonization rate for all sites was 53.1% (sample point II) and 64% (sample point III), respectively. The reduction was significant for every site, showing a rate of 88.5% for nose (II, III) and of 56.3% (II) and 68% (III) for all extranasal sites together. Of 32 patients, a median of 6.5 cfu MRSA/24 cm2 was obtained for the forehead before decolonization and 0.5 cfu MRSA/24 cm2 for the neck. A significant reduction (0 cfu MRSA/24 cm2) from both sites was shown after treatment. Before decolonization procedures, median MRSA levels for the nose, groin and axilla were 55, 6 and 0 cfu/swab. After treatment, MRSA from each of these sites was significantly reduced. We conclude that nasal mupirocin combined with octenidine dihydrochloride whole-body wash is effective in eradicating MRSA from patients with variable site colonization.

Mupirocin-resistant, methicillin-resistant Staphylococcus aureus: does mupirocin remain effective?

OBJECTIVE

To determine the efficacy of mupirocin ointment in reducing nasal colonization with mupirocin-susceptible, methicillin-resistant Staphylococcus aureus (MS MRSA) as well as mupirocin-resistant MRSA (MR MRSA).

DESIGN

Prospective evaluation in which patients colonized with MRSA were treated twice daily with 2% topical mupirocin ointment for 5 days.

SETTING

James H. Quillen Veterans' Affairs Medical Center.

PATIENTS

Forty hospitalized patients with two anterior nares cultures positive for MRSA within a 7-day period.

METHODS

Treated patients had post-treatment cultures at day 3 and weeks 1, 2, and 4. Isolates underwent mupirocin-susceptibility testing and DNA typing. MRSA clearance and type turnover were assessed for isolates that were mupirocin-susceptible, low-level (LL) MR MRSA and high-level (HL) MR MRSA.

RESULTS

Post-treatment nares cultures on day 3 were negative for 78.5%, 80%, and 27.7% of patients with MS MRSA, LL-MR MRSA, and HLMR MRSA, respectively. Sustained culture negativity at 1 to 4 weeks was more common in the MS MRSA group (91%) than in the LL-MR MRSA group (25%) or the HL-MR MRSA group (25%). Positive post-treatment cultures usually showed the same DNA pattern relative to baseline. Plasmid curing of 18 HL-MR MRSA resulted in 15 MS MRSA and 3 LL-MR MRSA.

CONCLUSIONS

Mupirocin was effective in eradicating MS MRSA, but strains of MR MRSA often persisted after treatment. This appeared to reflect treatment failure rather than exogenous recolonization. MR MRSA is now more prevalent and it is appropriate to sample MRSA populations for mupirocin susceptibility prior to incorporating mupirocin into infection control programs.

Mupirocin resistance in clinical isolates of Staphylococcus aureus

One hundred isolates of Staphylococcs aureus were collected in a laboratory serving several hospitals and clinics in southeastern Wisconsin and tested for mupirocin susceptibility. Only two isolates of S. aureus showed mupirocin resistance. The mupirocin-resistant isolates were from hospitalized patients with positive blood cultures.

Staphylococcal resistance revisited: community-acquired methicillin resistant Staphylococcus aureus--an emerging problem for the management of skin and soft tissue infections

PURPOSE OF REVIEW

In the community non-localized or deep staphylococcal skin and soft tissue infections are typically managed with beta-lactamase stable penicillins. The aims of this review are (1) to evaluate the evidence for the emergence of new strains of community-acquired methicillin resistant Staphylococcus aureus (MRSA), (2) to identify the reasons for their significant association with cutaneous infections, and (3) to consider how they arose and how big a threat they pose to the management of such infections outside hospitals.

RECENT FINDINGS

MRSA are emerging as significant community pathogens, especially in previously healthy children with no recognizable risk factors, and are predominantly associated with skin and soft tissue infections (especially abscesses and cellulitis). When present, risk factors are generally similar to those for infection with methicillin susceptible S. aureus. The MRSA isolates associated with such infections may not be entirely 'new', but could represent the displacement of some hospital clones (e.g. EMRSA-15 or variants thereof) to the community as well as the de-novo generation of novel MRSA clones by multiple horizontal transmissions of the mecA gene into methicillin susceptible S. aureus with different genetic backgrounds, some of which are already circulating globally. Community-acquired MRSA from diverse locations are non multiresistant and almost always contain the novel type IV SCCmec commonly found in coagulase-negative staphylococci, but also in hospital-associated gentamicin susceptible MRSA from France, the paediatric clone and in EMRSA-15.

SUMMARY

More local data on CA-MRSA infections are needed so that dermatologists and community physicians can assess the risk of such infections amongst their patients and avoid the inappropriate administration of beta-lactams. No simple change in prescribing practices will entirely alleviate selective pressure for the spread of community-acquired MRSA and not exacerbate resistance in pyogenic streptococci, commonly found together with S. aureus in skin and soft tissue infections. The importance of hygiene in preventing the spread of community-acquired MRSA in the community must be reemphasized.

Nasal Carriage of Staphylococcus aureus As a Risk Factor for Skin and Soft Tissue Infections

Nasal carriage of Staphylococcus aureus is a major risk factor for the development of S. aureus infection, including skin and soft tissue infections and foreign body infections, such as catheter-associated bacteremia and peritonitis. In this article, we review the recent literature on S. aureus nasal carriage, including the emergence of methicillin- resistant S. aureus in the community, the pathophysiology of nasal carriage, and the epidemiology and prevention of S. aureus infections associated with nasal carriage.