Prevalence and Risk Factors for Multidrug-Resistant Organisms Colonization in Long-Term Care Facilities Around the World: A Review

Elderly people confined to chronic care facilities face an increased risk of acquiring infections by multidrug-resistant organisms (MDROs). This review presents the current knowledge of the prevalence and risk factors for colonization by MDROs in long-term care facilities (LTCF), thereby providing a useful reference to establish objectives for implementing successful antimicrobial stewardship programs (ASPs). We searched in PubMed and Scopus for studies examining the prevalence of MDROs and/or risk factors for the acquisition of MDROs in LTCF. One hundred and thirty-four studies published from 1987 to 2020 were included. The prevalence of MDROs in LTCF varies between the different continents, where Asia reported the highest prevalence of extended-spectrum ß-lactamase (ESBL) Enterobacterales (71.6%), carbapenem resistant (CR) Enterobacterales (6.9%) and methicillin-resistant Staphylococcus aureus (MRSA) (25.6%) and North America the highest prevalence to MDR Pseudomonas aeruginosa (5.4%), MDR Acinetobacter baumannii (15.0%), vancomycin-resistant Enterococcus spp. (VRE) (4.0%), and Clostridioides difficile (26.1%). Furthermore, MDRO prevalence has experienced changes over time, with increases in MDR P. aeruginosa and extended spectrum ß-lactamase producing Enterobacterales observed starting in 2015 and decreases of CR Enterobacterales, MDR A. baumannii, VRE, MRSA and C. difficile. Several risk factors have been found, such as male sex, chronic wounds, the use of medical devices, and previous antibiotic use. The last of these aspects represents one of the most important modifiable factors for reducing colonization with MDROs through implementing ASPs in LTCF.

In Vitro Activity of the Bacteriophage Endolysin HY-133 against Staphylococcus aureus Small-Colony Variants and Their Corresponding Wild Types

Nasal carriage of methicillin-susceptible (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA) represents both a source and a risk factor for subsequent infections. However, existing MRSA decolonization strategies and antibiotic treatment options are hampered by the duration of administration and particularly by the emergence of resistance. Moreover, beyond classical resistance mechanisms, functional resistance as the formation of the small-colony variant (SCV) phenotype may also impair the course and treatment of S. aureus infections. For the recombinant bacteriophage endolysin HY-133, rapid bactericidal and highly selective in vitro activities against MSSA and MRSA has been shown. In order to assess the in vitro efficacy of HY-133 against the SCV phenotype, minimal inhibitory (MIC) and minimal bactericidal concentrations (MBC) were evaluated on clinical SCVs, their isogenic wild types, as well as on genetically derived and gentamicin-selected SCVs. For all strains and growth phases, HY-133 MIC and MBC ranged between 0.12 and 1 mg/L. Time-kill studies revealed a fast-acting bactericidal activity of HY-133 resulting in a ≥3 - log10 decrease in CFU/mL within 1 h compared to oxacillin, which required 4⁻24 h. Since the mode of action of HY-133 was independent of growth phase, resistance pattern, and phenotype, it is a promising candidate for future S. aureus decolonization strategies comprising rapid activity against phenotypic variants exhibiting functional resistance.

Methicillin-Resistant Staphylococcus aureus in Extended-Care Facilities: Experiences in a Veterans Affairs Nursing Home and a Review of the Literature

Objectives:

To delineate the spread of methicillin-resistant Staphylococcus aureus (MRSA) in a nursing home care unit (NHCU), determine its consequences, and discuss this experience in the context of reports fi-om other nursing homes.

Design:

Observational and descriptive; routine and special surveillance for MRSA, including a facility-wide prevalence survey; characterization of MRSA isolates by disk diffusion and agar diluation susceptibility studies and restriction enzyme analysis of plasmid (REAP) DNA.

Setting and Patients:

A 120-bed skilled nursing facility that is an integral part of the Veterans' Affairs Medical Center (VAMC), Portland, Oregon. The patients are predominantly elderly men with severe underlying diseases and functional impairments.

Results:

An asymptomatic carrier brought MRSA into the NHCU in December 1987. During the next 15 months, 24 additional MRSA cases were detected. A prevalence survey conducted in March 1989 indicated that 39 (34%) of the 114 patients and 8 (7%) of the 117 employees were colonized or infected with MRSA. All strains were resistant to ciprofloxacin. REAP DNA indicated that 37 of 41 strains recovered in the March survey had identical patterns. Although 16 episodes of MRSA infection occurred in NHCU residents during 1988 through 1989, the outbreak had little effect on overall patterns of infectious morbidity and mortality in the facility. The outbreak, however, did result in an increased MRSA caseload at the medical center's acute-care division.

Conclusions:

During the last three years, MRSA colonization and infection have become common in the NHCU at the Portland VAMC; this experience parallels that reported by several nursing homes in other parts of the country.

Treatment of Infection and Colonization Caused by Methicillin-Resistant Staphylococcus aureus

The mechanism of methicillin resistance confers resistance to all available B-lactam antibiotics; consequently, B-lactam antibiotics have no role in therapy of methicillin-resistant Staphylococcus aureus (MRSA) infections. Vancomycin remains the drug of choice. Teicoplanin and daptomycin are two investigational antibiotics related to vancomycin in structure and in spectrum of activity. In clinical trials employing relatively low doses, neither was as effective as vancomycin. Trials at higher doses are on-going. Quinolones, ciprofloxacin in particular, have been used successfully to treat infections caused by MRSA; however, the usefulness of quinolones may be limited by the tendency of resistance to emerge during therapy. Quinolones probably should be used only in combination with another active agent, such as rifampin, when treating serious infections caused by MRSA. Other agents may be active in vitro against MRSA, but clinical data showing their effectiveness are lacking. Rifampin combination regimens appear most effectively to eradicate colonization with MRSA.

Topical Therapy for Methicillin-Resistant Staphylococcus aureus Colonization Impact on Infection Risk

Objective.

We evaluated the usefulness of topical decolonization therapy for reducing the risk of methicillin-resistant Staphylococcus aureus (MRSA) infection among MRSA-colonized inpatients.

Design.

Retrospective cohort study.

Setting and Intervention.

Three hospitals with universal surveillance for MRSA; at their physician's discretion, colonized patients could be treated with a 5-day course of nasal mupirocin calcium 2%, twice daily, plus Chlorhexidine gluconate 4% every second day.

Patients and Methods.

MRSA carriers were later retested for colonization (407 subjects; study 1) or followed up for development of MRSA infection (933 subjects; study 2). Multivariable methods were used to determine the impact of decolonization therapy on the risks of sustained colonization (in study 1) and MRSA infection (in study 2).

Results.

Independent risk factors for sustained colonization included residence in a long-term care facility (odds ratio [OR], 1.8 [95% confidence interval {CI}, 1.1–3.2]) and a pressure ulcer (OR, 2.3 195% CI, 1.2–4.4]). Mupirocin at any dose decreased this risk, particularly during the 30-60-day period after therapy; mupirocin resistance increased this risk (OR, 4.1 [95% CI, 1.6–10.7]). Over a median follow-up duration of 269 days, 69 (7.4%) of 933 patients developed infection. Independent risk factors for infection were length of stay (hazard ratio [HR], 1.2 per 5 additional days [95% CI, 1.0–1.4]), chronic lung disease (HR, 1.7 [95% CI, 1.0–2.8]), and receipt of non-MRSA-active systemic antimicrobial agents (HR, 1.8 [95% CI, 1.1–3.1]). Receipt of mupirocin did not affect the risk of infection, although there was a trend toward delayed infection among patients receiving mupirocin (median time to infection, 50 vs 15.5 days; P = .06).

Conclusions.

Mupirocin-based decolonization therapy temporarily reduced the risk of continued colonization but did not decrease the risk of subsequent infection.

Outcome of MRSA carriers in neurological early rehabilitation

BACKGROUND

Colonization with MRSA is believed to have deteriorating effects on neurological rehabilitation patients because MRSA carriers need to be isolated.

METHODS

Medical records of neurological early rehabilitation patients (most of them after stroke) admitted to a large rehabilitation facility in Northern Germany in 2010 have been carefully reviewed with respect to MRSA status, outcome variables (functional independence), morbidity, and length of stay (LOS).

RESULTS

74/569 (13.0%) patients were MRSA positive on admission. MRSA carriers had a significantly longer LOS in early neurological rehabilitation (63.7 (37.1) vs. 25.8 (24.5) days, p < 0.001), worse functional status on admission (Barthel index (BI) 13.6 (9.9) vs. 25.6 (24.1), p < 0.001), worse Glasgow Coma Scale (9.5 (3.2) vs. 12.0 (3.3), p < 0.001), more co-diagnoses (20.5 (5.1) vs. 13.3 (5.5), p < 0.001), and higher Patient Clinical Complexity Levels (PCCL). The outcome was significantly worse among MRSA positive patients (BI 25.5 (21.2) vs. 47.4 (31.0), p < 0.001; Early Rehabilitation Index -47.3 (51.4) vs. -26.0 (35.4), p < 0.001). Isolated patients had slightly less therapy per day (131.6 (16.6) vs. 140.2 (18.7) min/day, p < 0.001), but the overall sum of therapy was significantly larger in the MRSA positive group due to longer LOS.

CONCLUSIONS

Functional recovery of MRSA carriers in early neurological rehabilitation is worse than in MRSA negative patients. Poorer outcome is not resulting from isolation (less therapy) but from functional status and higher morbidity on admission.

Eradication of an epidemic methicillin-resistant Staphylococcus aureus (MRSA) from a geriatric university hospital: evidence from a 10-year follow-up

We report on a successful eradication of methicillin-resistant S. aureus (MRSA) after an epidemic in 1992 in the geriatric ward of a tertiary-care hospital. After identification of MRSA in seven patients, all patients and staff members in the geriatric ward underwent screening. A multifaceted intervention plan was implemented: contact isolation, optimization of infection control and decolonization of all MRSA carriers. Thirty-two patients and five staff members were found to be MRSA carriers. Twenty one of 32 (66%) patients and all five staff members were successfully decolonized. Seven of 32 (22%) patients died during the epidemic before decolonization. A couple was discharged with persisting MRSA colonization and two individuals were lost to follow-up. The eradication of the epidemic clone was proven by systematic screenings in 1995 and 1997. Since then, the strain has no longer been identified in our institution, based on epidemiological surveillance and molecular typing of all MRSA strains obtained from any specimen. This study provides strong evidence that long-term eradication of an MRSA epidemic in a hospital is feasible, and endemicity of MRSA after an outbreak can be avoided. The successful bundle approach for eradication of MRSA during an epidemic is expensive, but the long-term benefits likely outweigh the initial heavy use of resources.

Mupirocin-resistant, methicillin-resistant Staphylococcus aureus strains in Canadian hospitals

Mupirocin resistance in Staphylococcus aureus is increasingly being reported in many parts of the world. This study describes the epidemiology and laboratory characterization of mupirocin-resistant methicillin-resistant S. aureus (MRSA) strains in Canadian hospitals. Broth microdilution susceptibility testing of 4,980 MRSA isolates obtained between 1995 and 2004 from 32 Canadian hospitals was done in accordance with CLSI guidelines. The clinical and epidemiologic characteristics of strains with high-level mupirocin resistance (HLMup(r)) were compared with those of mupirocin-susceptible (Mup(s)) strains. MRSA strains were characterized by pulsed-field gel electrophoresis (PFGE) and typing of the staphylococcal chromosomal cassette mec. PCR was done to detect the presence of the mupA gene. For strains with mupA, plasmid DNA was extracted and subjected to Southern blot hybridization. A total of 198 (4.0%) HLMup(r) MRSA isolates were identified. The proportion of MRSA strains with HLMup(r) increased from 1.6% in the first 5 years of surveillance (1995 to 1999) to 7.0% from 2000 to 2004 (P < 0.001). Patients with HLMup(r) MRSA strains were more likely to have been aboriginal (odds ratio [OR], 3.7; 95% confidence interval [CI], 1.5 to 9.4; P = 0.006), to have had community-associated MRSA (OR, 2.2; 95% CI, 1.0 to 5.0; P = 0.05), and to have been colonized with MRSA (OR, 1.7; 95% CI, 1.0 to 3.0; P = 0.04). HLMup(r) MRSA strains were also more likely to be resistant to fusidic acid (21% versus 4% for mupirocin-susceptible strains; P < 0.001). All HLMup(r) MRSA strains had a plasmid-associated mupA gene, most often associated with a 9-kb HindIII fragment. PFGE typing and analysis of the plasmid profiles indicate that both plasmid transmission and the clonal spread of HLMup(r) MRSA have occurred in Canadian hospitals. These results indicate that the incidence of HLMup(r) is increasing among Canadian strains of MRSA and that HLMup(r) MRSA is recovered from patients with distinct clinical and epidemiologic characteristics compared to the characteristics of patents with Mup(s) MRSA strains.

Clonal dissemination and mupA gene polymorphism of mupirocin-resistant Staphylococcus aureus isolates from long-term-care facilities in South Korea

We identified 25 high-level mupirocin-resistant (MuH) and 21 low-level mupirocin-resistant (MuL) Staphylococcus aureus isolates from eight long-term-care facilities (LTCFs). The pulsed-field gel electrophoresis patterns of 19 MuH and 19 MuL isolates from two facilities were identical for 18 and 15 isolates, respectively. The most predominant mupA restriction fragment length polymorphism type was found in 21 MuH isolates. We conclude that clonal transmission of MuH and MuL S. aureus strains occurred in these LTCFs. This is the first report of clonal transfer of mupirocin resistance in LTCFs.

The throat: an important site for MRSA colonization

In order to evaluate the value of bacterial cultures taken from the throat, 266 patients with MRSA were retrospectively assessed. At the time when MRSA was first detected in the patient, the most frequent sites positive for MRSA were a skin lesion (110 patients, 41%), the anterior nares (109 patients, 41%), and the throat (102 patients, 38%). In 26%, 17%, and 17% of the patients, a skin lesion, the anterior nares, and the throat, respectively, were the only site where MRSA was seen. In 123 patients cultured for MRSA because of a close contact with an already known MRSA patient, 65 patients (53%) were positive for MRSA in their throat and in 40 patients (33%), throat was the only sample site with MRSA at the time when the patient was found to be MRSA positive. 146 of the 266 patients (55%) were colonized with MRSA in the throat any time throughout the period they were MRSA positive. We conclude that throat is an important reservoir for MRSA and that samples taken from the throat should be included in screening patients for MRSA.

Peritoneal catheter exit-site infections: predisposing factors, prevention and treatment

Catheter-related infections, exit-site-tunnel infections and peritonitis remain the Achilles heel of peritoneal dialysis. Although the overall incidence of peritoneal-dialysis-related infectious complications has been reduced since the introduction of the Y-set and double bag system, approximately one-fifth of peritonitis episodes are associated with catheter exit-site and tunnel infections. Since its development in 1968, the Tenckhoff catheter has become one of the most widely used peritoneal catheters, and many have proposed that a number of modifications have made it a better choice. Controversies concerning the effect on exit-site infections of catheter(s) with one or two cuffs, with straight, coiled, Swan-Neck, or other modifications led to the randomized controlled studies that are reviewed in this paper. Several studies have confirmed that mupirocin, applied at the exit-site as part of regular exit-site care, reduces the risk of S. aureus exit-site and tunnel infections. Recently, the emergence on a world-wide basis of mupirocin-resistant S. aureus (MuRSA) in peritoneal dialysis patients has brought this prophylactic strategy into question. However the low frequency of resistant organisms after four years of mupirocin prophylaxis suggests that we can continue its use with annual surveillance. Once established, exit-site infections may respond to appropriate treatment, but if not the only option may be catheter removal and replacement. Although peritonitis risk has decreased over the past decade, mainly due to improvements in connection technology, exit-site and tunnel infections have not. An exit-site infection that does not respond to treatment may lead to tunnel infection and to persistent peritonitis, which may require catheter removal and occasionally discontinuation of the peritoneal dialysis. Therefore it is important to be familiar with these factors that predispose to exit-site infection and to know how to prevent and to treat such infections. This review will discuss factors that predispose to catheter-related exit-site infections, techniques of exit-site care, and ways to prevent exit-site infection, with emphasis on S. aureus infections and their treatment.

Randomized clinical trial of preoperative intranasal mupirocin to reduce surgical-site infection after digestive surgery

BACKGROUND

Compromised patients subjected to major digestive surgery frequently develop infective complications caused by methicillin-resistant Staphylococcus aureus (MRSA), which may have dangerous consequences. This was a prospective randomized study to determine whether intranasal mupirocin could reduce postoperative infective complications in patients having digestive surgery.

METHODS

A total of 395 patients who underwent abdominal digestive surgery were assigned randomly into two groups: a treated group (193 patients) and controls (202). Patients in the treated group were given 30 mg mupirocin calcium hydrate ointment topically to each nostril three times a day on each of the 3 days before operation. The untreated group received no mupirocin treatment.

RESULTS

Most infections were due to Gram-negative bacteria in both groups. There were 21 Gram-positive infections detected at the surgical site, ten in the treated group and 11 in control patients. The incidence of pneumonia was significantly different between the groups (none in the treated group and five in control patients; P = 0.028). Four of five patients with pneumonia had a sputum culture containing MRSA.

CONCLUSION

Intranasal mupirocin treatment had no significant impact on surgical-site infection after digestive surgery.

Comparison of silver sulfadiazine 1%, mupirocin 2%, and fusidic acid 2% for topical antibacterial effect in methicillin-resistant staphylococci-infected, full-skin thickness rat burn wounds

Silver sulfadiazine 1%, mupirocin 2%, and fusidic acid 2% were compared to assess the antibacterial effect of a once-daily application on experimental rat 15% full-skin thickness burn wounds seeded 24 hours earlier with a 10 standard strain of methicillin-resistant staphylococci. The quantitative counts of seeded organism in burn eschar and subjacent muscle were determined at postburn day 7, beside the cultures of blood and lung biopsies. All tested topical agents were equally effective against methicillin-resistant in reducing local burn wound bacterial count and preventing systemic infection.

Infections and antibiotic resistance in nursing homes

Infections occur frequently in nursing home residents. The most common infections are pneumonia, urinary tract infection, and skin and soft tissue infection. Aging-associated physiologic and pathologic changes, functional disability, institutionalization, and invasive devices all contribute to the high occurrence of infection. Antimicrobial agent use in nursing homes is intense and usually empiric. All of these factors contribute to the increasing frequency of antimicrobial agent-resistant organisms in nursing homes. Programs that will limit the emergence and impact of antimicrobial resistance and infections in nursing homes need to be developed.

Significant reduction in methicillin-resistant Staphylococcus aureus ventilator-associated pneumonia associated with the institution of a prevention protocol

OBJECTIVE

To determine whether the institution of a methicillin-resistant Staphylococcus aureus prevention protocol was associated with a decrease in methicillin-resistant S. aureus ventilator-associated pneumonia in long-term, acute care ventilator patients.

DESIGN

A retrospective chart review comparing the number of episodes of clinical pneumonia per patient ventilator day in the 12 months preceding and 24 months following the introduction of the protocol.

SETTING

University affiliated, long-term, acute care ventilator hospital.

PATIENTS

Long-term, acute care ventilated patients who presented with clinical pneumonia.

INTERVENTIONS

Addition of a methicillin-resistant S. aureus prevention protocol. In addition to universal precautions, the protocol consisted of mupirocin 2% ointment applied to the anterior nares, and whole body washing with chlorhexidine. All patients were given mupirocin and chlorhexidine twice weekly. Patients were cohorted in the same room if they were, or had been, infected or colonized with methicillin-resistant S. aureus in any anatomical location or at any time. This procedure replaced strict isolation of methicillin-resistant S. aureus-infected or colonized individuals.

MEASUREMENTS AND MAIN RESULTS

Clinical pneumonia was diagnosed when a patient developed fever, bronchorrhea, increased white blood cell count, methicillin-resistant S. aureus isolated from the tracheal aspirate, and new or increasing infiltrate on chest roentgenograph. During the 12 months preceding the protocol, there were 0.2% episodes of methicillin-resistant S. aureus ventilator-associated pneumonia per ventilated patient day compared with 0.026% in the 24 months after the protocol (p < .001). The relative and absolute risk reductions associated with the introduction of the protocol were 87% and 6, respectively.

CONCLUSIONS

The period following the institution of the protocol showed a significant reduction in episodes of clinical pneumonia compared with the 12-month period preceding the use of the protocol (p < .001). Thus, we conclude that the introduction of this protocol is associated with a significant decrease in methicillin-resistant S. aureus ventilator-associated pneumonia.

The efficacy of intranasal mupirocin in the prevention of staphylococcal infections: a review of recent experience

Staphylococcal infections remain an important cause of morbidity and mortality. Methicillin-resistant Staphylococcus aureus (MRSA) present a particular problem because of the costs of treatment and containing outbreaks. The role of nasal carriage of staphylococci in the epidemiology of staphylococcal infection has been recognized for over 30 years. Until recently, eradication of nasal carriage of S. aureus has proved difficult, with a variety of topical and systemic agents yielding poor results with either little discernible effect on nasal carriage or rapid recolonization. Mupirocin is a novel topical antibiotic with excellent antibacterial activity against staphylococci, including MRSA. Intranasal administration of calcium mupirocin has achieved excellent results in the eradication of nasal carriage of S. aureus and producing an associated reduction in S. aureus infection in a variety of clinical settings, including MRSA outbreaks, neonatal nurseries, haemodialysis, cardiothoracic surgery and familial staphylococcal infections. This article reviews the efficacy and safety of intranasal mupirocin in the prevention of staphylococcal infections.

Analysis of nosocomial outbreaks with multiply and methicillin-resistant Staphylococcus aureus (MRSA) in Germany: implications for hospital hygiene

Two outbreaks of nosocomial infections with MRSA, one in a urological unit in connection with transurethral prostatectomy and the other in an orthopaedic clinic with infections after implantation of prosthetic hips, have been analyzed on the basis of typing MRSA by phage-patterns, plasmid profiles and genomic DNA fragment patterns. Main reasons for these outbreaks were obviously mistakes in hospital hygiene and an inappropriate antibiotic prophylaxis (in the first outbreak a quinolone over about 7 days, in the second a third generation cephalosporin). Both outbreaks could be stopped by measures of hospital hygiene including isolated or cohort nursing of affected patients, and change in antibiotic prophylaxis. Intensive care units (ICUs) are more often affected by MRSA than other clinical settings. As described by the example of an outbreak with MRSA in a municipal hospital, ICUs can play a special role in intrahospital spread of MRSA. The recently observed inter-regional clonal interhospital dissemination of MRSA in Germany is mainly due to a transfer of patients between hospitals; prewarning of the hospital of destination and a number of hygiene measures can prevent further spread.

Long-term efficacy of a program to control methicillin-resistant Staphylococcus aureus

The long-term efficacy of a program to control methicillin-resistant Staphylococcus aureus (MRSA) was evaluated in a 350-bed university hospital. Three periods were monitored: pre-epidemic (January 1989-November 1989), outbreak (December 1989-June 1990) and control program (July 1990-December 1992) periods. Control measures included cohort isolation, patient care measures and therapy (oral cotrimoxazole plus fusidic acid ointment) of MRSA carriage in patients, roommates and personnel. A total of 117 MRSA-infected patients were detected. For each period respectively, MRSA incidence (number of cases per 1,000 patient-days) was 3.2, 8.2 and 2.0 in the intensive care unit (ICU) and 0.08, 0.23 and 0.26 in the general wards. During the outbreak there was a 2.7-fold overall increase of baseline MRSA incidence (p < 0.02). The crude mortality was 68% and the attributable mortality was estimated to be 50%. The program was estimated to have prevented 76% (CI95 28-91, p < 0.0001) of expected MRSA cases and 85% (CI95 62-94, p < 0.0001) of expected fatalities due to MRSA in the ICU, but it had no significant effect in the general wards. The program did not control vancomycin consumption.

Methicillin-resistant Staphylococcus aureus (MRSA) colonization in patients with spinal cord injury

Methicillin-resistant Staphylococcus aureus (MRSA) colonization has been a problem in the Rancho Los Amigos Medical Center (RLAMC) since 1978. This study reviews the latest 2 years' use of a protocol to prevent the spread of MRSA while allowing spinal cord injured patients to continue to participate in the rehabilitation program. The protocol included management in a private room, bathing with hexachlorophene, monitoring positive sites and clearing patients after 3 weeks of negative cultures. Clusters of cases were investigated by obtaining nasal cultures from the personnel. Sixty-seven of 584 (11%) SCI patients were colonized from July 1989 to July 1991. The prevalence of MRSA colonization was significantly greater in the pressure ulcer management service (PMS) 49/184 (27%) than in the rehabilitation spinal injury service (SIS) 18/400 (5%). The body sites colonized were wounds (58/67), nares (37/67), throat (30/67), urine (27/67) and perineum (17/67). Oral therapy with combinations of sulfamethoxazole trimethoprim (SXT) or Novobiocin with rifampin together with topical antibiotics (nares and wound sites), used in nine patients with healing wounds or recent flap surgery, resulted in clearing of the colonization in all cases. Identification and treatment of carriers in the personnel and use of preadmission screening cultures for MRSA in patients with pressure ulcers resulted in reduced inpatient admission.

Attempts to eradicate methicillin-resistant Staphylococcus aureus from a long-term-care facility with the use of mupirocin ointment

PURPOSE

To assess the impact of the use of mupirocin ointment on colonization, transmission, and infection with methicillin-resistant Staphylococcus aureus (MRSA) in a long-term-care facility.

PATIENTS AND METHODS

All 321 residents of a Veterans Affairs long-term-care facility from June 1990 through June 1991 were studied for MRSA colonization and infection. MRSA-colonized patients received mupirocin ointment to nares in the first 7 months and to nares and wounds in the second 5 months. The effect of mupirocin use on MRSA colonization and infection was monitored. All S. aureus strains isolated were tested for the development of resistance to mupirocin.

RESULTS

A total of 65 patients colonized with MRSA received mupirocin ointment. Mupirocin rapidly eliminated MRSA at the sites treated in most patients by the end of 1 week. Weekly maintenance mupirocin was not adequate to prevent recurrences--40% of patients had recurrence of MRSA. Overall, MRSA colonization in the facility, which was 22.7% +/- 1% prior to the use of mupirocin, did not change when mupirocin was used in nares only (22.2% +/- 2.1%), but did decrease to 11.5% +/- 1.8% when mupirocin was used in nares and wounds. Although colonization decreased, roommate-to-roommate transmission and MRSA infection rates, low to begin with, did not change when mupirocin was used. Mupirocin-resistant MRSA strains were isolated in 10.8% of patients.

CONCLUSIONS

Mupirocin ointment is effective at decreasing colonization with MRSA. However, constant surveillance was required to identify patients colonized at admission or experiencing recurrence of MRSA during maintenance treatment. Long-term use of mupirocin selected for mupirocin-resistant MRSA strains. Mupirocin should be saved for use in outbreak situations, and not used over the long term in facilities with endemic MRSA colonization.

Methicillin-resistant Staphylococcus aureus: a consensus review of the microbiology, pathogenesis, and epidemiology with implications for prevention and management

Methicillin-resistant Staphylococcus aureus (MRSA) has become a major nosocomial pathogen in community hospitals, long-term-care facilities, and tertiary care hospitals. The basic mechanism of resistance is alteration in penicillin-binding proteins of the organism. Methods for isolation by culture and typing of the organism are reviewed. MRSA colonization precedes infection. A major reservoir is the anterior nares. MRSA is usually introduced into an institution by a colonized or infected patient or health care worker. The principal mode of transmission is via the transiently colonized hands of hospital personnel. Indications for antibiotic therapy for eradication of colonization and treatment of infection are reviewed. Infection control guidelines and discharge policy are presented in detail for acute-care hospitals, intensive care and burn units, outpatient settings, and long-term-care facilities. Recommendations for handling an outbreak, surveillance, and culturing of patients are presented based on the known epidemiology.

Methicillin-resistant Staphylococcus aureus colonization in a long-term-care facility

OBJECTIVE

To study the prevalence and risk factors for colonization with MRSA at a long-term-care facility.

DESIGN

Cross-sectional surveillance culture survey.

SETTING

A 233-bed university-affiliated long-term-care facility.

MEASUREMENTS

Surveillance cultures for MRSA were performed on patients of two adjacent nursing units and on new admissions to the entire facility over a 4-month period.

RESULTS

On the chronic medical unit, where patients known to be colonized had been cohorted, 20 of 38 (52.6%) were colonized vs 3 of 67 (4.5%) on the skilled/intermediate unit (P less than 0.001), suggesting that little intra-facility spread of MRSA occurs. Twenty-four of 55 (43.6%) chronic medical admissions were colonized vs 6 of 63 (9.5%) admitted to the other units (P less than 0.001). Thirteen of 30 (43.3%) admissions were not previously known to be colonized. By univariate analysis, colonized admissions were younger and more often male; had more listed diagnoses, including pressure sores, a previous positive MRSA culture, and urinary incontinence; were more often fed by feeding tube; and had longer durations of hospital stay prior to admission. Logistic regression analysis showed that the most powerful independent predictors of colonization at admission were: a prior positive culture for MRSA (OR 8.8, 95% CI 2.4, 32.4), male sex (OR 8.2, 95% CI 2.3, 29.7), urinary incontinence (OR 3.8, 95% CI 1.4, 10.4), and presence of pressure sores (OR 2.9, 95% CI 0.9, 9.2).

CONCLUSIONS

Unrecognized colonization of nursing home residents with MRSA is common, and nursing homes are unwittingly repositories for patients colonized with MRSA following acute hospitalization. Gloving and careful attention to handwashing may limit spread of MRSA within nursing homes, and identification of colonized patients may be facilitated by targeted surveillance cultures of the most debilitated patients at admission.

Immediate and long-term efficacy of systemic antibiotics for eradicating nasal colonization with Staphylococcus aureus

The efficacy of nine antibiotics used in different nonrandomized regimens for eradicating nasal colonization with Staphylococcus aureus was investigated in 72 patients. Dicloxacillin, erythromycin and three cephalosporins had eradicated colonization in about 75% of cases at early follow-up (less than or equal to 20 days) and in less than or equal to 50% at late follow-up (greater than or equal to 20 days). Clindamycin had eradicated colonization in all 13 patients at both follow-up times. One of two patients was successfully treated with fleroxacin, as were three of five with enoxacin. Among 21 patients treated with ofloxacin, colonization was eradicated in 20 (95%) at early follow-up and in all six of those from whom late follow-up cultures were obtained. Thus, clindamycin and ofloxacin appear to be useful systemic antibiotics for eradicating nasal colonization with Staphylococcus aureus.

Methicillin-resistant Staphylococcus aureus in Minnesota nursing homes

OBJECTIVE

To assess the experience of Minnesota nursing homes with methicillin-resistant Staphylococcus aureus (MRSA) and the policies and procedures used for its control.

DESIGN

A 12-question survey, with primarily categorical responses, was mailed to the Directors of Nursing of all Minnesota long-term-care facilities. A follow-up mailing was sent to non-responders 5 weeks later. The mailing included a cover letter, a description of the study and its purposes, and a stamped return envelope. Four weeks after the second mailing, all non-responding institutions were contacted by telephone and invited to participated by mail or by completing the survey by telephone.

SETTING

All long-term-care facilities in Minnesota licensed for skilled and intermediate care.

PARTICIPANTS

The survey was directed to the Directors of Nursing of the long-term-care facilities with the request that, if another individual was better able to complete it, the survey be forwarded to them.

RESULTS

Completed responses were obtained from 88% (395/445) of all long-term-care facilities in Minnesota. Forty-eight institutions (12%) had residents colonized or infected with MRSA. Only four (8%) of these facilities stated that MRSA was a problem; however, 33 (69%) of facilities with MRSA had sought outside help or consultation from a variety of sources for its control. Few facilities (7%) had cultured residents specifically for MRSA. Policies regarding the admission of colonized or infected persons were reported by 14% and 21% of facilities, respectively, and over 40% of these policies stated that persons with MRSA would not be accepted. Policies regarding the care of MRSA-colonized or -infected persons were not uniform. Both metropolitan and non-metropolitan facilities had residents with MRSA.

CONCLUSIONS

Our results suggest that MRSA in long-term-care facilities may be a widespread and underrecognized problem. There is a need to develop uniform policies for the control of MRSA in nursing homes. These policies should consider the sources and objectives of long-term-care facilities.

Use of antimicrobial susceptibility testing for epidemiology and the selection of oral, parenteral and topical regimens for control of CAPD-associated Staphylococcus aureus infection

Staphylococcus aureus is an important cause of peritonitis in patients undergoing continuous ambulatory peritoneal dialysis (CAPD). Using standard broth microdilution and disk diffusion methodology, we evaluated the in vitro activity of selected antimicrobial agents against S. aureus strains isolated from CAPD patients to assess candidate regimens for 1) topical agent control of colonization, 2) oral chemotherapy of CAPD infectious complications, and 3) parenteral treatment of serious CAPD-associated staphylococcal infections. A total of 34 isolates (31 patients) of S. aureus were available for testing, including 29 isolates (29 patients) from pericatheter skin, four isolates (four patients) from the nares, and one isolate from an episode of peritonitis. Six of the isolates were oxacillin-resistant (ORSA). The antimicrobial agents tested by broth microdilution included 17 different quinolones, 10 cephalosporins, six glycopeptides, two aminoglycosides, and imipenem. A total of eight potential topical agents, including the antistaphylococcal agent mupirocin, were tested by disk diffusion. All of the quinolones, with the exception of nalidixic acid (MIC90 greater than 16 micrograms/ml), had excellent activity against both ORSA and oxacillin-susceptible S. aureus (OSSA) with the most active agent being WIN57273 (MIC90 less than or equal to 0.015 microgram/ml). Imipenem and the cephalosporins, with the exception of cefixime, ceftazidime, and E-1040, possessed good activity against OSSA. None of the beta-lactam agents tested were active against ORSA. Likewise, the aminoglycosides, amikacin and gentamicin, exhibited good activity against OSSA strains but no activity against ORSA strains. All glycopeptides tested demonstrated excellent activity against ORSA strains. Of the topical antimicrobial agents tested only bacitracin, mupirocin, and nitrofurantoin were active against all OSSA and ORSA strains tested.(ABSTRACT TRUNCATED AT 250 WORDS)

Methicillin-resistant Staphylococcus aureus in extended-care facilities: experiences in a Veterans' Affairs nursing home and a review of the literature

OBJECTIVES

To delineate the spread of methicillin-resistant Staphylococcus aureus (MRSA) in a nursing home care unit (NHCU), determine its consequences, and discuss this experience in the context of reports from other nursing homes.

DESIGN

Observational and descriptive; routine and special surveillance for MRSA, including a facility-wide prevalence survey; characterization of MRSA isolates by disk diffusion and agar dilution susceptibility studies and restriction enzyme analysis of plasmid (REAP) DNA.

SETTING AND PATIENTS

A 120-bed skilled nursing facility that is an integral part of the Veterans' Affairs Medical Center (VAMC), Portland, Oregon. The patients are predominantly elderly men with severe underlying diseases and functional impairments.

RESULTS

An asymptomatic carrier brought MRSA into the NHCU in December 1987. During the next 15 months, 24 additional MRSA cases were detected. A prevalence survey conducted in March 1989 indicated that 39 (34%) of the 114 patients and 8 (7%) of the 117 employees were colonized or infected with MRSA. All strains were resistant to ciprofloxacin. REAP DNA indicated that 37 of 41 strains recovered in the March survey had identical patterns. Although 16 episodes of MRSA infection occurred in NHCU residents during 1988 through 1989, the outbreak had little effect on overall patterns of infectious morbidity and mortality in the facility. The outbreak, however, did result in an increased MRSA caseload at the medical center's acute-care division.

CONCLUSIONS

During the last three years, MRSA colonization and infection have become common in the NHCU at the Portland VAMC; this experience parallels that reported by several nursing homes in other parts of the country.

Treatment of infection and colonization caused by methicillin-resistant Staphylococcus aureus

The mechanism of methicillin resistance confers resistance to all available beta-lactam antibiotics; consequently, beta-lactam antibiotics have no role in therapy of methicillin-resistant Staphylococcus aureus (MRSA) infections. Vancomycin remains the drug of choice. Teicoplanin and daptomycin are two investigational antibiotics related to vancomycin in structure and in spectrum of activity. In clinical trials employing relatively low doses, neither was as effective as vancomycin. Trials at higher doses are on-going. Quinolones, ciprofloxacin in particular, have been used successfully to treat infections caused by MRSA; however, the usefulness of quinolones may be limited by the tendency of resistance to emerge during therapy. Quinolones probably should be used only in combination with another active agent, such as rifampin, when treating serious infections caused by MRSA. Other agents may be active in vitro against MRSA, but clinical data showing their effectiveness are lacking. Rifampin combination regimens appear most effectively to eradicate colonization with MRSA.

Increasing Prevalence of Methicillin-Resistant Staphylococcus aureus in the United States

In the period 1975 to 1981, methicillin-resistant Staphylococcus aureus (MRSA) emerged as an important nosocomial pathogen in tertiary care centers in the United States. To determine if the prevalence of this organism has continued to increase, a questionnaire was sent to hospital epidemiologists in 360 acute care hospitals. A total of 256 (71%) of the 360 individuals responded. Overall, 97% (246/256) of responding hospitals reported having patients with MRSA in the period 1987 through 1989. Respondents in 217 hospitals provided estimates of the number of cases seen in 1987, 1988 and 1989. The percentage of respondents reporting one or more patients with MRSA increased from 88% in 1987 to 96.3% in 1989 (p = .0008). The percent of respondents reporting large numbers (≥50) of cases per year increased from 18% in 1987 to 32% in 1989 (p = .0006). Increasing frequency of large outbreaks was observed in community, community-teaching, federal, municipal and university hospitals.

Methicillin-resistant Staphylococcus aureus in long-term care facilities

Methicillin-resistant Staphylococcus aureus (MRSA) infections emerged as a problem in acute-care hospitals in this country in the 1970s. However, as is true of most nosocomial infections, long-term care facilities have not been exempt from those issues that plague acute-care hospitals, and, indeed, bring their own peculiar circumstances to bear on the problem. Infection and colonization with MRSA has been no exception and has evolved as a major infection control issue within long-term care facilities. Aside from an early report of MRSA cultured from patients in a nursing home in Seattle, Washington in 1969, data on MRSA in long-term care facilities have appeared only recently. In spite of the dearth of information, many long-term care facilities established policies relating to MRSA in the early to mid-1980s; often these policies were developed in hopes of excluding MRSA from their facility, and for many reasons often have not helped solve the problems associated with MRSA in long-term care facilities.