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.     

The epidemiology of mupirocin resistance among methicillin-resistant Staphylococcus aureus at a Veterans' Affairs hospital.

OBJECTIVE: To describe the clinical and molecular epidemiology of mupirocin-resistant (MR) and mupirocin-susceptible (MS) methicillin-resistant Staphylococcus aureus (MRSA) at a Veterans' Affairs hospital and to assess risk factors associated with the acquisition of MR MRSA. DESIGN: All clinical MRSA isolates for the period October 1990 through March 1995 underwent susceptibility testing to mupirocin. Mupirocin resistance trends were measured, and MS MRSA and MR MRSA isolates underwent typing by pulsed-field gel electrophoresis (PFGE). A retrospective case-control study was conducted to evaluate risk factors for having MR versus MS MRSA. SETTING: The James H. Quillen Veterans' Affairs Medical Center in Mountain Home, Tennessee, included a 324-bed acute-care hospital, a 120-bed nursing home, and a 525-bed domiciliary. Colonizations and infections with MRSA were endemic, and mupirocin ointment was commonly used. PATIENTS: Inpatients and outpatients at the facility. RESULTS: MS MRSA was recovered from 506 patients and MR MRSA from 126. Among MR MRSA isolates, 58% showed low-level mupirocin resistance (minimum inhibitory concentration [MIC] > or = 4 to 256 microg/mL), and 42% showed high-level mupirocin resistance (MIC > or = 512 microg/mL). A significant increase (P=.002) in the number of high-level MR isolates occurred during the 1993 to 1995 period. A case-control study showed that presence of a decubitus ulcer correlated with high-level resistant isolates (P<.05). The distribution of PFGE patterns did not differ for MR and MS MRSA CONCLUSIONS: Use of mupirocin ointment in a program aimed at managing endemic MRSA infection or colonization resulted in a significant increase in the recovery of high-level MR MRSA isolates. These isolates appeared to emerge from our existing MRSA pool. A case-control study provided few clues concerning patients likely to harbor MR MRSA. We confirmed the position that the extended use of mupirocin ointment should be avoided in settings where MRSA is endemic.     

A clinical trial of mupirocin in the eradication of methicillin-resistant Staphylococcus aureus nasal carriage in a digestive disease unit

We assessed the incidence of nasal carriage of methicillin-resistant Staphylococcus aureus (MRSA) on admission, the rate of acquisition during the hospital stay and the relationship with subsequent infection in a digestive disease unit. The efficacy of a program of nasal carriage eradication with mupirocin was evaluated simultaneously. Over one year 484 patients were studied prospectively on admission for nasal and stool carriage of MRSA, then every week for nasal carriage. Nearly 70% (68.8%) of patients had chronic liver diseases. Nasal carriers were assigned to a five-day course of intranasal mupirocin ointment. One hundred and seventeen (24.2%) patients were MRSA positive, 57 (11.8%) of which were carriers on admission and 60 (12.4%) acquired carriage. Of these, 86 were treated with mupirocin with a success rate of 98.8% and 25.9% of them recolonized. Fourteen patients were retreated, to allow eradication in 71.4% of cases. Seventy percent of these became carriers again. One high-level mupirocin-resistant strain was isolated before treatment and seven during or after treatment. Hospital stay and stool carriage were independently associated with reacquisition (P=0.0105 and P=0.0462, respectively). Molecular analysis showed identity between the strains isolated from infection samples and from nasal swabs during the same week. For every patient who became recolonized, nasal strains isolated before and after eradication were the same in 70% of cases. Mortality during hospital stay was independently associated with age (P=0.0081), MRSA nasal carriage (P=0.02631), MRSA infection (P<0.0001) and liver disease (P=0.0017). This study did not show a change in the prevalence rate of infection in the unit during treatment with mupirocin. This treatment should only be attempted once due to the risk of emergence of high-level resistant strains.     

Antimicrobial therapy for methicillin-resistant Staphylococcus aureus colonization in residents and staff of a Veterans Affairs nursing home care unit.

OBJECTIVE: To evaluate the effect of antimicrobial therapy on patients and staff colonized with methicillin-resistant Staphylococcus aureus (MRSA) in a skilled nursing facility and to assess the role of the environment as a potential reservoir for MRSA in the nursing home setting. DESIGN: As part of a comprehensive program to control an MRSA outbreak in a nursing home, patients and staff colonized with MRSA received 1 of 3 antimicrobial decolonization regimens depending upon the site and extent of colonization. Followup cultures were performed during therapy and on days 2, 7, 14, and 30 following the completion of therapy. Cultures of the patients' inanimate environment (pajamas, sheet, and floor) were obtained during and after therapy. Antimicrobial susceptibility tests were performed on 54 MRSA isolates obtained before and 44 MRSA isolates recovered after therapy. SETTING: A 120-bed Veterans Affairs nursing home care unit. PARTICIPANTS: Thirty-six patients and 7 staff nurses colonized with MRSA at 1 or more sites. INTERVENTION: Decolonization therapy with rifampin, trimethoprim-sulfamethoxazole, and clindamycin used alone or in various combinations for 5 or 10 days in conjunction with other infection control measures employed to combat the MRSA outbreak. RESULTS: Twenty (56%) of the 36 NHCU patients were either persistently colonized or became recolonized with MRSA during the 30-day followup period. Positive cultures on day 3 during therapy frequently identified patients who subsequently exhibited persistent or recurrent colonization. Before therapy, 92% of MRSA isolates were susceptible to rifampin, whereas only 43% of the isolates obtained after therapy were susceptible. Sixteen (80%) of 20 patients with persistent or recurrent colonization had rifampin-resistant strains of MRSA isolated after therapy. Twenty-three (18%) of 125 environmental cultures obtained during and after therapy from patients who exhibited persistent or recurrent colonization were positive for MRSA, in contrast to 9 (8%) of 107 from patients who were successfully decolonized. CONCLUSIONS: The decolonization component of the outbreak control program was judged to be ineffective and potentially hazardous because colonization persisted or recurred in more than half of the patients, and substantial antimicrobial resistance was noted in MRSA stains isolated after therapy. Resistance, especially to rifampin, and possibly re-acquisition of MRSA from other human or environmental sources were 2 factors that appeared to impede the decolonization effort.     

Control of a methicillin-resistant Staphylococcus aureus outbreak in a neonatal intensive care unit by unselective use of nasal mupirocin ointment

In September 1996, an outbreak of methicillin-resistant Staphylococcus aureus (MRSA) colonization occurred in the neonatal intensive care unit (NICU) of our hospital. After failing to control the outbreak by conventional methods we implemented an intranasal blanket use programme of mupirocin ointment from the beginning of November 1997. In the programme, patients who had been carrying MRSA received intranasal administration of the ointment three times daily for the first three days and consecutively three times weekly, while newly admitted patients and those who had not been colonized were prophylactically medicated three times weekly. This blanket administration was executed for one month. Methicillin-resistant Staphylococcus aureus colonization became undetectable in all but one intubated inpatient who had already been colonized before the start of the programme, and no new acquisitions occurred until the middle of January 1998, seven weeks after the termination of the blanket use programme. The rate of colonized patients in the unit also decreased. During and after the programme, neither an increase in minimum inhibitory concentration for the antibiotic nor apparent adverse reactions in any of the treated patients were observed. We concluded that this procedure is an effective method of controlling an MRSA outbreak in an NICU when the outbreak cannot be managed with conventional measures.     

The in-vitro activity of povidone-iodinecream against Staphylococcus aureus and its bioavailability in nasal secretions

Due to the emergence of mupirocin-resistance in some epidemic strains of methicillin resistant Staphylococcus aureus (EMRSA) and the appearance of EMRSA with intermediate resistance to vancomycin, we evaluated the in-vitro activity of 5% povidone-iodine ('Betadine') cream as a possiblealternative to mupirocin for the elimination of nasal carriage of S. aureus. As judged by enrichment culture, povidone-iodine was bactericidal against three mupirocin-sensitive strains of S. aureus from nasal carriers, and against mupirocin-resistant and -sensitive strains of EMRSA types 3, 15 and 16, after incubation with povidone-iodine for 1.0 min at 32 degrees C. Mupirocin nasal ointment did not prevent growth after 180 min incubation. In a quantitative suspension test, 1:100 dilution of povidone-iodine cream completely eliminated an inoculum of 10(8)cfu/mL of all nine test organisms after incubation at 32 degrees C for 1.0 min, and 1:1000 dilution reduced cfu, by a factor of 10(5). After direct inoculation of the povidone-iodine cream to give 10(5)cfu/g, none of the test strains were recoverable after 30 s, giving a killing rate of approximately 10(4)cfu/s; for mupirocin nasal ointment, the maximum reduction of mupirocin-sensitive strains was ten fold after 3 h. Povidone-iodine activity was not detectable in sensitivity-testing agar, although 0.025% of povidone-iodine was detectable in a 15% nutrient strength tryptone soya agar. Using this minimal medium, the addition of nasal secretions (from any of 11 samples) reduced the activity of povidone-iodine by 80-90%, but mupirocin activity was unaffected. One millilitre of nasal secretions inactivated the equivalent of approximately 22.5 mg of povidone-iodine. These results suggest that povidone-iodine cream may have a role in the prevention of colonization and infection caused by MRSA, including mupirocin-resistant strains.     

Effectiveness of topical chlorhexidine powder as an alternative to hexachlorophane for the control of Staphylococcus aureus in neonates

We routinely phage-type Staphylococcus aureus isolates from high-risk inpatients each week. This surveillance approach previously identified a five-year outbreak of a methicillin-susceptible S. aureus strain (MSSA, PT 53,85), which affected 202 babies on a regional neonatal unit. We previously reported this outbreak and the multiple staged infection control measures that were required to end it. These included strict emphasis on hand hygiene, environmental and staff surveillance sampling, application of topical triclosan solution and hexachlorophane powder, aseptic handling of a skin protectant material, and use of topical mupirocin for staff nasal carriers of the endemic MSSA strain and for babies colonized or infected with S. aureus. In summer 2000 topical hexachlorophane powder became unavailable and we therefore substituted topical 1% chlorhexidine powder as part of routine umbilical decontamination. We have continued prospective S. aureus surveillance for the past five years to monitor the effect of this practice change. We observed a continued decline in the numbers of monthly MSSA isolates from neonatal unit babies. Since the substitution of chlorhexidine for hexachlorophane, the median monthly number of MRSA isolates has been 0.5 (range 0-4). Only sporadic S. aureus PT 53,85 isolates were recovered. Control of S. aureus in our regional neonatal unit, in particular an endemic MSSA strain, was maintained when topical umbilical hexachlorophane powder was substituted with 1% chlorhexidine powder.     

Bacitracin versus mupirocin for Staphylococcus aureus nasal colonization.

We performed a randomized prospective study of 5-day treatment with topical mupirocin or bacitracin for the elimination of Staphylococcus aureus nasal colonization in healthcare workers (HCWs). Nasal cultures were obtained from 141 HCWs, 37 (26%) of whom showed S. aureus. After 72 to 96 hours of treatment, the organism was eradicated in 15 (94%) of 16 by mupirocin and in 8 (44%) of 18 by bacitracin (P = .0031). Similar efficacy was demonstrated at 30 days. Mupirocin may be more effective than bacitracin for eradication of S. aureus in healthy HCWs.     

Selective use of intranasal mupirocin and chlorhexidine bathing and the incidence of methicillin-resistant Staphylococcus aureus colonization and infection among intensive care unit patients.

OBJECTIVE: To determine whether the use of chlorhexidine bathing and intranasal mupirocin therapy among patients colonized with methicillin-resistant Staphylococcus aureus (MRSA) would decrease the incidence of MRSA colonization and infection among intensive care unit (ICU) patients. METHODS: After a 9-month baseline period (January 13, 2003, through October 12, 2003) during which all incident cases of MRSA colonization or infection were identified through the use of active-surveillance cultures in a combined medical-coronary ICU, all patients colonized with MRSA were treated with intranasal mupirocin and underwent daily chlorhexidine bathing. RESULTS: After the intervention, incident cases of MRSA colonization or infection decreased 52% (incidence density, 8.45 vs 4.05 cases per 1,000 patient-days; P=.048). All MRSA isolates remained susceptible to chlorhexidine; the overall rate of mupirocin resistance was low (4.4%) among isolates identified by surveillance cultures and did not increase during the intervention period. CONCLUSIONS: We conclude that the selective use of intranasal mupirocin and daily chlorhexidine bathing for patients colonized with MRSA reduced the incidence of MRSA colonization and infection and contributed to reductions identified by active-surveillance cultures. This finding suggests that additional strategies to reduce the incidence of MRSA infection and colonization--beyond expanded surveillance--may be needed.     

Impact of treating Staphylococcus aureus nasal carriers on wound infections in cardiac surgery

Staphylococcus aureus is a common cause of postoperative wound infections, and nasal colonization by this organism is an important factor in the development of infections. Treatment with mupirocin can eradicate the organism in the short term, and prophylactic treatment of colonized patients may prevent postoperative S. aureus infections. A double-blind, randomized, placebo-controlled trial was performed to determine whether nasal mupirocin administered pre-operatively to S. aureus carriers reduces the rates of sternal and leg wound infections after cardiac surgery. The study enrolled 263 patients with nasal S. aureus undergoing elective cardiac surgery at St. Michael's Hospital, Toronto, Canada. Patients were assessed for infections in the immediate postoperative period and two months later. Two hundred and fifty-seven patients were included in the intention-to-treat analysis and re-analysed according to the actual treatment applied. Wound infections occurred in 17 (13.5%) mupirocin recipients and 11 (9.1%) placebo recipients (P=0.319), with seven (5.4%) and six (4.7%) sternal infections, respectively. Two (1.6%) wound infections were acquired postoperatively in the mupirocin group, neither of which were caused by S. aureus. The placebo group had three (2.4%) nosocomial wound infections, with two (1.6%) S. aureus bacteraemias (P=0.243). Among patients receiving mupirocin, 106 (81.5%) cleared S. aureus compared with 59 (46.5%) patients receiving placebo (P<0.0001). There was no significant difference between intention-to-treat and actual treatment groups. Prophylactic intranasal mupirocin administered to S. aureus carriers did not reduce the rates of overall surgical site infections by S. aureus, and only showed a trend towards decreased incidence of nosocomial S. aureus infections.     

Value of whole-body washing with chlorhexidine for the eradication of methicillin-resistant Staphylococcus aureus: a randomized, placebo-controlled, double-blind clinical trial.

BACKGROUND: Whole-body washing with antiseptic solution has been widely used as part of eradication treatment for colonization with methicillin-resistant Staphylococcus aureus (MRSA), but evidence for the effectiveness of this measure is limited. OBJECTIVE: To study the efficacy of whole-body washing with chlorhexidine for the control of MRSA. DESIGN: Randomized, placebo-controlled, double-blinded clinical trial. SETTING: University Hospital of Heidelberg and surrounding nursing homes. PATIENTS: MRSA carriers who were not treated concurrently with antibiotics effective against MRSA were eligible for the study. INTERVENTION: Five days of whole-body washing with either 4% chlorhexidine solution (treatment group) or with a placebo solution. All patients received mupirocin nasal ointment and chlorhexidine mouth rinse. The outcome was evaluated 3, 4, 5, 9, and 30 days after treatment with swab samples taken from several body sites. RESULTS: Of 114 patients enrolled in the study (56 in the treatment group and 58 in the placebo group), 11 did not finish treatment (8 from the treatment group and 3 from the placebo group [P=.02]). At baseline, the groups did not differ with regard to age, sex, underlying condition, site of MRSA colonization, or history of MRSA eradication treatment. Eleven patients were MRSA-free 30 days after treatment (4 from the treatment group and 7 from the placebo group [P=.47]). Only groin-area colonization was significantly better eradicated by the use of chlorhexidine. The best predictor for total eradication was a low number of body sites positive for MRSA. Adverse effects were significantly more frequent in the treatment group than in the placebo group (any symptom, 71% vs 33%) but were reversible in most cases. CONCLUSION: Whole-body washing can reduce skin colonization, but it appears necessary to extend eradication measures to the gastrointestinal tract, wounds, and/or other colonized body sites if complete eradication is the goal.     

"Pulse" nasal mupirocin maintenance regimen in patients undergoing continuous ambulatory peritoneal dialysis.

OBJECTIVE: To determine, among patients undergoing continuous ambulatory peritoneal dialysis (CAPD) who were Staphylococcus aureus nasal carriers, if periodic brief "pulses" of nasal mupirocin calcium ointment 2% after completion of a mupirocin eradication protocol would maintain these patients free of carriage. DESIGN: Noncomparative, nonblinded study with historical controls. SETTING: A county medical center. PATIENTS: Patients in a CAPD program during the period April 1996 to May 1998. METHODS: All patients in the CAPD program had monthly nasal cultures for S. aureus. After informed consent, S. aureus nasal carriers were administered mupirocin to the nares twice a day for 5 days followed by nasal mupirocin twice monthly. Peritonitis and exit-site infection rates were monitored independently by CAPD nursing staff. Patients were monitored monthly for adverse effects of mupirocin and compliance with the maintenance regimen. RESULTS: Twenty-four patients in the CAPD program were enrolled in the study and had a median duration of follow-up of 8.5 months. Fifteen (63%) of the 24 patients remained free of nasal carriage on follow-up cultures. Of the 9 patients with positive nasal cultures during the study, 8 had only one positive culture. There was no significant difference in the mean yearly peritonitis rate or S. aureus peritonitis rate (January 1995-May 1998). However, there was a significant decrease in the mean yearly exit-site infection rates both overall (from 8.8 episodes per 100 patients dialyzed per month in 1995 to 4.0 in 1998; P = .008) and due to S. aureus (from 5.6 in 1995 to 0.9 in 1998; P = .03). Adverse effects of nasal mupirocin were mild overall; 1 patient was removed from the study due to an allergic reaction to mupirocin. CONCLUSIONS: Among CAPD patients who were S. aureus nasal carriers, periodic brief treatment with nasal mupirocin after an initial eradication regimen kept them free of carriage, for the most part, with few adverse effects. The pulse mupirocin regimen offers simplicity and possibly better compliance, as well as minimizing exposure to this agent, thereby possibly reducing the risk of resistance. Further studies are warranted to compare this regimen to other commonly used mupirocin maintenance regimens in dialysis patients.     

Gentamicin-methicillin-resistant Staphylococcus aureus: epidemiology and containment of an outbreak

An outbreak of gentamicin-methicillin-resistant Staphylococcus aureus (gentamicin-resistant MRSA) which occurred during 1983-84 at the Whittington Hospital, London, is described. This involved a total of 40 patients and staff and was largely confined to a urology ward. Seventeen of the patients had catheter-associated infections, 11 had wound infections and five had simultaneous infections of the urine and wound. Six members of staff and one patient were colonized with gentamicin-resistant MRSA. Vigorous and extensive infection control methods were carried out together with the use of a topical antibacterial nasal cream, mupirocin (pseudomonic acid). Seventeen patients and staff were treated with this agent and all were cleared of the original gentamicin-resistant MRSA. Sixteen patients who were not treated with mupirocin were discharged home still carrying the epidemic strain. Sporadic cases of gentamicin-resistant MRSA still occur at infrequent intervals.     

Prevalence of and risk factors for colonization with methicillin-resistant Staphylococcus aureus at the time of hospital admission.

OBJECTIVES: To determine the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) colonization among patients presenting for hospital admission and to identify risk factors for MRSA colonization. DESIGN: Surveillance cultures were performed at the time of hospital admission to identify patients colonized with S. aureus. A case-control study was performed to identify risk factors for MRSA colonization. SETTING: A tertiary-care academic medical center. PATIENTS: Adults presenting for hospital admission (N = 974). RESULTS: S. aureus was isolated from 205 (21%) of the patients for whom cultures were performed. Methicillin-sensitive S. aureus was isolated from 179 (18.4%) of the patients, and MRSA was isolated from 26 (2.7%) of the patients. All 26 MRSA-colonized patients had been admitted to a healthcare facility in the preceding year, had at least one chronic illness, or both. In multivariate analyses comparing MRSA-colonized patients with control-patients, admission to a nursing home (odds ratio [OR], 16.5; 95% confidence interval [CI95], 1.4 to 192.1; P = .025) or a hospitalization of 5 days or longer during the preceding year (OR, 3.91; CI95, 1.1 to 13.9; P = .035) were independent predictors of MRSA colonization. CONCLUSIONS: Patients colonized with MRSA admitted to this hospital likely acquired the organism during previous encounters with healthcare facilities. There was no evidence that MRSA colonization occurs commonly among low-risk individuals in this community. These data suggest that evaluation of recent healthcare exposures is essential if true community acquisition of MRSA is to be confirmed.     

Colonization of nursing professionals by Staphylococcus aureus

This cross-sectional study aimed to investigate the presence of Staphylococcus aureus in the saliva of the nursing team of a teaching hospital in the interior of S?o Paulo State. Three saliva samples were collected from 351 individuals with an interval of two months between each collection. All ethical aspects were considered. In 867 (82.3%) cultures there was no identification of Staphylococcus aureus in the saliva, in 88 (17.7%) cultures Staphylococcus aureus was isolated, 26 (2.5%) of which were resistant to methicillin. The prevalence of professionals colonized by Staphylococcus aureus was 41.0% (144/351), of which 7.1% (25/351) were characterized as methicillin-resistant Staphylococcus aureus. Transient carriers represented 81.2% and persistent carriers 18.8%. Resistance to mupirocin was 73.1% of MRSA and 9.3% of MSSA. The results demonstrate that it is the nurse and nursing technician that are the professional categories most susceptible to MRSA. Broader discussion on the thematic and interventions are needed.     

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

Topical mupirocin was able to interrupt colonization of 52% and 68% of methicillin-resistant Staphylococcus aureus (MRSA)-colonized patients carrying mupirocin-resistant and -sensitive strains, respectively, including 44.4% and 85.7% of those colonized only in the nares. Although a trend to decreased effectiveness was seen for clearing mupirocin-resistant MRSA, this agent can decolonize many patients with resistant strains.     

Effect of mupirocin on nasal carriage of Staphylococcus aureus

Mupirocin eliminates nasal carriage of Staphylococcus aureus among medical and surgical personnel for periods varying from several weeks up to one year. In persons recolonized after therapy densities of S. aureus populations in nares were much lower than in the same persons before therapy.     

Mupirocin for controlling methicillin-resistant Staphylococcus aureus: lessons from a decade of use at a university hospital.

BACKGROUND: From 1990 to 1995 at Hospital Universitário Clementino Fraga Filho, patients colonized or infected with methicillin-resistant Staphylococcus aureus (MRSA) were treated with mupirocin to eliminate MRSA carriage. In 1995, 65% of MRSA patients at this hospital had mupirocin-resistant isolates. Starting in 1996, mupirocin use was restricted to patients colonized, but not infected, with MRSA. OBJECTIVES: To describe the use of mupirocin for controlling MRSA over a decade and to analyze the molecular epidemiology of mupirocin-resistant MRSA infections at this hospital. SETTING: A 490-bed, tertiary-care university hospital. METHODS: The incidence densities of patients with MRSA and acquisition of mupirocin by the hospital were calculated for the period 1992-2001. S. aureus isolates from 1999-2000 were analyzed by pulsed-field gel electrophoresis. Mupirocin-resistant MRSA isolates from 1994-1995 and 1999-2000 were analyzed for ileS-2 gene background polymorphisms. RESULTS: The incidence density of MRSA patients increased slightly over time, whereas the purchase of mupirocin decreased dramatically. Mupirocin-resistant MRSA infections decreased from 65% in 1994-1995 to 15% in 1999-2000. The MRSA Brazilian clone, detected in 1992, was still highly prevalent. The same ileS-2 encoding plasmid found in 1994-1995 persisted in three identical MRSA isolates from 1999-2000 belonging to the Brazilian clone. CONCLUSIONS: After mupirocin use decreased, the ileS-2 encoding plasmid persisted in only a few Brazilian clone isolates. Our data on mupirocin-resistant MRSA incidence and mupirocin use strongly suggested that restricted use was related to decreased rates of mupirocin resistance at our hospital.     

Two hospital staff with throat carriage of methicillin-resistant Staphylococcus aureus,which had to be treated with systemic antibiotics

Two hospital staff, women aged 20 and 22 years, were inadvertently found to be positive for methicillin-resistant Staphylococcus aureus (MRSA). Both had been in a hospital outside of the Netherlands, but due to the long period of time that had elapsed since then, they did not fall under the standard protocol for MRSA screening. After the usual wash procedure with chlorhexidine and mupirocin nasal ointment treatment, they remained positive for MRSA in the throat culture. Both patients still had their pharyngeal tonsils and were suffering from throat complaints. After systemic treatment with two antibiotics, they both became MRSA-free. Throat carriership of MRSA might be a reason why MRSA eradication fails in the case of apparently healthy healthcare workers. The addition of a throat culture to the screening of healthcare workers would therefore be useful.     

Active surveillance to determine the impact of methicillin-resistant Staphylococcus aureus colonization on patients in intensive care units of a Veterans Affairs Medical Center.

OBJECTIVE: The impact of methicillin-resistant Staphylococcus aureus (MRSA) colonization on mortality has not been well characterized. We sought to describe the impact of MRSA colonization on patients admitted to intensive care units (ICUs) in the Birmingham Veterans Affairs Medical Center (VAMC). METHODS: We conducted a retrospective cohort study of ICU patients at the Birmingham VAMC during 2005 to evaluate the predictors of MRSA colonization and determine its effect on clinical outcomes. Surveillance cultures for MRSA were performed on admission to the ICU and weekly thereafter. Clinical findings, the incidence of MRSA infection, and mortality within 3 months after ICU admission were recorded. Predictors of mortality and S. aureus colonization were determined using multivariable models. RESULTS: S. aureus colonization was present in 97 (23.3%) of 416 patients screened, of whom 67 (16.1%) were colonized with methicillin-susceptible S. aureus (MSSA) and 30 (7.2%) with MRSA. All-cause mortality at 3 months among MRSA-colonized patients was significantly greater than that among MSSA-colonized patients (46.7% vs 19.4%; P = .009). MRSA colonization was an independent predictor of death (adjusted odds ratio [OR], 3.7 [95% confidence interval [CI], 1.5-8.9]; P = .003) and onset of MRSA infection after hospital discharge (adjusted OR, 7.6 [95% CI, 2.48-23.2]; P < .001). Risk factors for MRSA colonization included recent antibiotic use (adjusted OR, 4.8 [95% CI, 1.9-12.2]; P = .001) and dialysis (adjusted OR, 18.9 [95% CI, 2.1-167.8]; P = .008). CONCLUSIONS: Among ICU patients, MRSA colonization is associated with subsequent MRSA infection and an all-cause mortality that is greater than that for MSSA colonization. Active surveillance for MRSA colonization may identify individuals at risk for these adverse outcomes. Prospective studies of outcomes in MRSA-colonized patients may better define the role of programs for active MRSA surveillance.