Would active surveillance cultures help control healthcare-related methicillin-resistant Staphylococcus aureus infections?

Healthcare-associated Pneumonia: Clinical Features and Retrospective Analysis Over 10 Years

Background:

Healthcare-associated pneumonia (HCAP) is associated with drug-resistant pathogens and high mortality, and there is no clear evidence that this is due to inappropriate antibiotic therapy. This study was to elucidate the clinical features, pathogens, therapy, and outcomes of HCAP, and to clarify the risk factors for drug-resistant pathogens and prognosis.

Methods:

Retrospective observational study among hospitalized patients with HCAP over 10 years. The primary outcome was 30-day all-cause hospital mortality after admission. Demographics (age, gender, clinical features, and comorbidities), dates of admission, discharge and/or death, hospitalization costs, microbiological results, chest imaging studies, and CURB-65 were analyzed. Antibiotics, admission to Intensive Care Unit (ICU), mechanical ventilation, and pneumonia prognosis were recorded. Patients were dichotomized based on CURB-65 (low- vs. high-risk).

Results:

Among 612 patients (mean age of 70.7 years), 88.4% had at least one comorbidity. Commonly detected pathogens were Acinetobacter baumannii, Pseudomonas aeruginosa, and coagulase-negative staphylococci. Initial monotherapy with β-lactam antibiotics was the most common initial therapy (50%). Mean age, length of stay, hospitalization expenses, ICU admission, mechanical ventilation use, malignancies, and detection rate for P. aeruginosa, and Staphylococcus aureus were higher in the high-risk group compared with the low-risk group. CURB-65 ≥3, malignancies, and mechanical ventilation were associated with an increased mortality. Logistic regression analysis showed that cerebrovascular diseases and being bedridden were independent risk factors for HCAP.

Conclusion:

Initial treatment of HCAP with broad-spectrum antibiotics could be an appropriate approach. CURB-65 ≥3, malignancies, and mechanical ventilation may result in an increased mortality.

Epidemiology of Methicillin-ResistantStaphylococcus aureusand Vancomycin-ResistantEnterococcusin a Rural State

Background.

Most data on methicillin-resistantStaphylococcus aureus(MRSA) and vancomycin-resistant Enterococcus (VRE) isolates come from large tertiary care centers. Infection control personnel need to understand the epidemiology of MRSA and VRE across the continuum of care, including small rural hospitals, to develop effective control strategies.

Objective.

To describe the epidemiology of MRSA and VRE in Iowa.

Setting.

Fifteen hospitals in Iowa.

Methods.

Between July 1998 and June 2001, a total of 1,968S. aureusisolates and 1,845Enterococcusisolates from patients infected with these pathogens were examined. Multivariate models were developed to evaluate patient and institutional risk factors for MRSA infection and VRE infection.

Results.

The proportion ofS. aureusisolates resistant to methicillin was 31%, and the proportion ofEnterococcusisolates resistant to vancomycin was 6%. Independent risk factors for MRSA infection included residence in a long-term care facility, age of more than 60 years, hospitalization in a hospital with less than 200 short-term care beds, and acquiring the infection in the hospital. Independent risk factors for VRE infection included use of a central venous catheter, residence in a long-term care facility, acquisition of infection in the hospital, and hospitalization in a hospital with more than 200 short-term care beds.

Conclusions.

In Iowa, the epidemiology of MRSA differ from those of VRE. MRSA has become established in small rural hospitals. Effective MRSA control strategies may require inclusion of all hospitals in a state or region.

Emergence of Vancomycin-Resistant Enterococci in San Francisco Bay Area Hospitals During 1994 to 1998

Objective:

To determine the magnitude of van-comycin-resistant enterococci (VRE) in three counties in the San Francisco Bay area.

Design:

Active laboratory-based surveillance for VRE from January 1995 through December 1996 and a laboratory-based and hospital-based questionnaire survey for 1993 to 1994 and 1997 to 1998.

Setting:

All 33 general acute care hospitals in three counties in the San Francisco Bay area.

Participants:

Laboratories and infection control professionals serving these hospitals, and staff of the California Emerging Infections Program.

Results:

The number of hospitals reporting 1 or more patient clinical VRE isolates was 1 (3%) in 1993, 7 (21%) in 1994, 31 (94%) in 1995, and 33 (100%) in 1996 to 1998. The number of patient isolates increased from 1 in 1993 to 24 in 1994, 176 in 1995,429 in 1996, 730 in 1997, and 864 in 1998. Most VRE isolates in 1995 and 1996 were from urine and were not associated with serious clinical disease. However, the number of isolates from blood increased from 9 (6% of total) in 1995 to 44 (12% of the total) in 1996, 90 (14%) in 1997, and 100 (13%) in 1998.

Conclusions:

Our data document the rapid emergence and increase of VRE in all hospitals in three counties in the San Francisco Bay area during 1994 to 1998. Infection control measures for VRE together with antibiotic utilization programs should be implemented to limit further spread.

Infection control interventions in small rural hospitals with limited resources: results of a cluster-randomized feasibility trial

Background

There are few reports on the feasibility of conducting successful infection control (IC) interventions in rural community hospitals.

Methods

Ten small rural community hospitals in Idaho and Utah were recruited to participate in a cluster-randomized trial of multidimensional IC interventions to determine their feasibility in the setting of limited resources. Five hospitals were randomized to develop individualized campaigns to promote HH, isolation compliance, and outbreak control. Five hospitals were randomized to continue with current IC practices. Regular blinded observations of hand hygiene (HH) compliance were conducted in all hospitals as the primary outcome measure. Additionally, periodic prevalence studies of patient colonization with resistant pathogens were performed. The 5-months intervention time period was compared to a 4-months baseline period, using a multi-level logistic regression model.

Results

The intervention hospitals implemented a variety of strategies. The estimated average absolute change in “complete HH compliance” in intervention hospitals was 20.1% (range, 7.8% to 35.5%) compared to −3.1% (range −6.3% to 5.9%) in control hospitals (p = 0.001). There was an estimated average absolute change in “any HH compliance” of 28.4% (range 17.8% to 38.2%) in intervention hospitals compared to 0.7% (range −16.7 to 20.7%) in control hospitals (p = 0.010). Active surveillance culturing demonstrated an overall prevalence of MRSA carriage of 9.7%.

Conclusions

A replicable intervention significantly improved hand hygiene as a primary outcome measure despite barriers of geographic distance and lack of experience with study protocols. Active surveillance culturing identified unsuspected reservoirs of MRSA colonization and further promoted IC activity.

Modelling the impact of antibiotic use and infection control practices on the incidence of hospital-acquired methicillin-resistant Staphylococcus aureus: a time-series analysis

OBJECTIVES

Methicillin-resistant Staphylococcus aureus (MRSA) is a major nosocomial pathogen worldwide. A wide range of factors have been suggested to influence the spread of MRSA. The objective of this study was to evaluate the effect of antimicrobial drug use and infection control practices on nosocomial MRSA incidence in a 426-bed general teaching hospital in Northern Ireland.

METHODS

The present research involved the retrospective collection of monthly data on the usage of antibiotics and on infection control practices within the hospital over a 5 year period (January 2000-December 2004). A multivariate ARIMA (time-series analysis) model was built to relate MRSA incidence with antibiotic use and infection control practices.

RESULTS

Analysis of the 5 year data set showed that temporal variations in MRSA incidence followed temporal variations in the use of fluoroquinolones, third-generation cephalosporins, macrolides and amoxicillin/clavulanic acid (coefficients = 0.005, 0.03, 0.002 and 0.003, respectively, with various time lags). Temporal relationships were also observed between MRSA incidence and infection control practices, i.e. the number of patients actively screened for MRSA (coefficient = -0.007), the use of alcohol-impregnated wipes (coefficient = -0.0003) and the bulk orders of alcohol-based handrub (coefficients = -0.04 and -0.08), with increased infection control activity being associated with decreased MRSA incidence, and between MRSA incidence and the number of new patients admitted with MRSA (coefficient = 0.22). The model explained 78.4% of the variance in the monthly incidence of MRSA.

CONCLUSIONS

The results of this study confirm the value of infection control policies as well as suggest the usefulness of restricting the use of certain antimicrobial classes to control MRSA.

Infection control: worlds apart primary and secondary care

Healthcare associated infection continues to be a major cause of morbidity and mortality in healthcare. The fact that most of what has been written on the subject of infection control and prevention relates to the hospital setting is perhaps understandable given the proximity and immune status of patients in secondary care. However, the change of term from hospital-acquired infection to healthcare-associated infection acknowledges that a similar burden may exist in community settings. Influential reports suggest that community infection control is ill-defined and there is ongoing debate whether community-based infection control nursing involves the same or different approaches to hospital infection nursing. This paper explores some of the differences between infection control practice in primary and secondary care and examines the reasons for this.

Transmission via the face is one route of methicillin-resistant Staphylococcus aureus cross-infection within a hospital

BACKGROUND

It is generally accepted that hospital personnel must not touch their faces, and indeed must not elevate their hands above the shoulder in the ward, because many bacteria including Staphylococcus aureus colonize the face. However, possible methicillin-resistant Staphylococcus aureus (MRSA) cross-infection by way of faces has not yet been properly examined.

METHODS

One hundred and seventy-eight isolates from 159 inpatients from February 1999 to January 2000 were subjected to chromosomal DNA analysis by pulsed-field gel electrophoresis (PFGE).

RESULTS

The 178 MRSA isolates were classified into 43 PFGE types. Cross-infection was more frequent in the Department of Neurology [average number of patients per PFGE pattern (n/PFGE) = 4.0] than in the other six nonsurgical departments (n/PFGE = 1.0-1.6), and more frequent in four surgical departments (n/PFGE = 2.0-4.5) than in the other eight (n/PFGE = 1.0-1.7). In neurology, patients' faces were more often touched for examination of the cranial nerves than in the other departments. In the above four surgical departments, organs in the face were chiefly operated upon, and the patients' faces were also touched for care before and after the operation.

CONCLUSIONS

Our study reveals the possibility of MRSA being transmitted by way of patients' faces in a hospital.

Guidelines for the control and prevention of meticillin-resistant Staphylococcus aureus (MRSA) in healthcare facilities

Meticillin-resistant Staphylococcus aureus (MRSA) remains endemic in many UK hospitals. Specific guidelines for control and prevention are justified because MRSA causes serious illness and results in significant additional healthcare costs. Guidelines were drafted by a multi-disciplinary group and these have been finalised following extensive consultation. The recommendations have been graded according to the strength of evidence. Surveillance of MRSA should be undertaken in a systematic way and should be fed back routinely to healthcare staff. The inappropriate or unnecessary use of antibiotics should be avoided, and this will also reduce the likelihood of the emergence and spread of strains with reduced susceptibility to glycopeptides, i.e. vancomycin-intermediate S. aureus/glycopeptide-intermediate S. aureus (VISA/GISA) and vancomycin-resistant S. aureus (VRSA). Screening for MRSA carriage in selected patients and clinical areas should be performed according to locally agreed criteria based upon assessment of the risks and consequences of transmission and infection. Nasal and skin decolonization should be considered in certain categories of patients. The general principles of infection control should be adopted for patients with MRSA, including patient isolation and the appropriate cleaning and decontamination of clinical areas. Inadequate staffing, especially amongst nurses, contributes to the increased prevalence of MRSA. Laboratories should notify the relevant national authorities if VISA/GISA or VRSA isolates are identified.

Impact of an aggressive infection control strategy on endemic Staphylococcus aureus infection in liver transplant recipients

BACKGROUND

Methicillin-resistant Staphylococcus aureus has emerged as a leading pathogen in transplant recipients and has become endemic in many institutions where transplantation is performed. The role of active surveillance programs based on the detection of colonization in the prevention of S. aureus infection in liver transplant recipients has not been defined.

METHODS

A total of 47 consecutive patients who underwent liver transplantation during 1996-1999 were compared with 97 patients who received a liver transplant during 2000-2004 after implementation of an intensive intervention program that included use of surveillance cultures to detect nasal and rectal colonization, use of cohorting and contact isolation precautions, and decolonization with intranasal mupirocin therapy.

RESULTS

The rate of new acquisition of S. aureus colonization of nares after transplantation decreased from 45.6% (21 of 46 patients) during the preintervention period to 9.9% (9 of 91 patients) during the postintervention period (P<.001). An increased length of hospital stay (odds ratio, 1.03; 95% confidence interval, 1.01-1.05; P<.002) was associated with new carriage acquisition, and transplantation during the postintervention period (odds ratio, 0.21; 95% confidence interval, 0.08-0.51; P<.001) was independently protective against new carriage. The rate of infection due to S. aureus decreased from 40.4% (19 of 47 patients) during the preintervention period to 4.1% (4 of 97 patients) during the postintervention period (P<.001), and the rate of bacteremia decreased from 25.5% (12 of 47 patients) to 4.1% (4 of 97 patients), respectively (P<.001). Overall, S. aureus infections occurred more frequently among patients with new carriage than among patients who were carriers at the time of transplantation (P<.001) or patients who were noncarriers (P<.001).

CONCLUSIONS

Use of active surveillance cultures to detect colonization and implementation of targeted infection control interventions proved to be effective in curtailing new acquisition of S. aureus colonization and in decreasing the rate of S. aureus infection that was endemic in our population of liver transplant recipients.

Epidemiology and outcomes of health-care-associated pneumonia: results from a large US database of culture-positive pneumonia

CONTEXT

Traditionally, pneumonia developing in patients outside the hospital is categorized as community acquired, even if these patients have been receiving health care in an outpatient facility. Accumulating evidence suggests that health-care-associated infections are distinct from those that are truly community acquired.

OBJECTIVE

To characterize the microbiology and outcomes among patients with culture-positive community-acquired pneumonia (CAP), health-care-associated pneumonia (HCAP), hospital-acquired pneumonia (HAP), and ventilator-associated pneumonia (VAP).

DESIGN AND SETTING

A retrospective cohort study based on a large US inpatient database.

PATIENTS

A total of 4,543 patients with culture-positive pneumonia admitted into 59 US hospitals between January 1, 2002, and December 31, 2003, and recorded in a large, multi-institutional database of US acute-care hospitals (Cardinal Health-Atlas Research Database; Cardinal Health Clinical Knowledge Services; Marlborough, MA).

MAIN MEASURES

Culture data (respiratory and blood), in-hospital mortality, length of hospital stay (LOS), and billed hospital charges.

RESULTS

Approximately one half of hospitalized patients with pneumonia had CAP, and > 20% had HCAP. Staphylococcus aureus was a major pathogen in all pneumonia types, with its occurrence markedly higher in the non-CAP groups than in the CAP group. Mortality rates associated with HCAP (19.8%) and HAP (18.8%) were comparable (p > 0.05), and both were significantly higher than that for CAP (10%, all p < 0.0001) and lower than that for VAP (29.3%, all p < 0.0001). Mean LOS varied significantly with pneumonia category (in order of ascending values: CAP, HCAP, HAP, and VAP; all p < 0.0001). Similarly, mean hospital charge varied significantly with pneumonia category (in order of ascending value: CAP, HCAP, HAP, and VAP; all p < 0.0001).

CONCLUSIONS

The present analysis justified HCAP as a new category of pneumonia. S aureus was a major pathogen of all pneumonias with higher rates in non-CAP pneumonias. Compared with CAP, non-CAP was associated with more severe disease, higher mortality rate, greater LOS, and increased cost.

Rapid detection of methicillin-resistant Staphylococcus aureus from screening enrichment broths by real-time PCR

The aim of this study was to evaluate real-time PCR (LightCycler) kits for the detection of methicillin-resistant Staphylococcus aureus in enrichment broth using 200 sets of patient screening swab samples. One hundred sets were processed using a lysostaphin/lysozyme extraction method and a further 100 were tested using a column extraction kit. The PCR kits with lysostaphin/lysozyme lysis showed 95.7% sensitivity, 90.8% specificity, and negative and positive predictive values of 98.6% and 75.9%, respectively, compared with 88%, 95.9%, 84.6% and 95.9%, respectively, with the column extraction kit.

Antimicrobial prophylaxis for surgery: an advisory statement from the National Surgical Infection Prevention Project

In January 2003, leadership of the Medicare National Surgical Infection Prevention Project hosted the Surgical Infection Prevention Guideline Writers Workgroup meeting. The objectives were to review areas of agreement among the published guidelines for surgical antimicrobial prophylaxis, to address inconsistencies, and to discuss issues not currently addressed. The participants included authors from most of the published North American guidelines for antimicrobial prophylaxis and several specialty colleges. The workgroup reviewed currently published guidelines for antimicrobial prophylaxis. Nominal group process was used to draft a consensus paper that was widely circulated for comment. The consensus positions of the workgroup include that infusion of the first antimicrobial dose should begin within 60 minutes before surgical incision and that prophylactic antimicrobial agents should be discontinued within 24 hours of the end of surgery. This advisory statement provides an overview of other issues related to antimicrobial prophylaxis including specific suggestions regarding antimicrobial selection.

Direct detection of Staphylococcus aureus from adult and neonate nasal swab specimens using real-time polymerase chain reaction

Nasal carriage of Staphylococcus aureus is considered a source of subsequent infection in health care settings. Utilization of real-time polymerase chain reaction (PCR) for detection of S. aureus has the potential to dramatically affect infection control practice by rapidly identifying S. aureus-colonized patients. We developed and validated the use of real-time PCR for detection of S. aureus colonization in two patient populations. Paired nasal swabs were collected from 299 neonates and from 151 adult patients at Evanston Hospital. One swab was used for culture and the other placed into a bacterial lysis solution containing achromopeptidase. The DNA liberated was used as the template for real-time PCR with primers for the femA gene. SYBR Green was used for amplicon detection. In the neonatal population the sensitivity, specificity, predictive value positive and predictive value negative for culture and PCR was 92% versus 96%, 100% versus 100%, 100% versus 100%, and 98% versus 99%, respectively. In the adults the results were 90% versus 100%, 100% versus 98%, 100% versus 96%, and 95% versus 100%, respectively. Real-time PCR was able to detect S. aureus in 2 hours compared to 1 to 4 days for culture and provided sensitivity equal to or greater than culture.

Antimicrobial drug use and methicillin-resistant Staphylococcus aureus, Aberdeen, 1996-2000

Relationships between antimicrobial use and MRSA prevalence are analyzed in Aberdeen, Scotland.

Similar to many hospitals worldwide, Aberdeen Royal Infirmary has had an outbreak of methicillin-resistant Staphylococcus aureus (MRSA). In this setting, the outbreak is attributable to two major clones. The relationships between antimicrobial use and MRSA prevalence were analyzed by time-series analysis. From June 1997 to December 2000, dynamic, temporal relationships were found between monthly %MRSA and previous %MRSA, macrolide use, third-generation cephalosporin use, and fluoroquinolone use. This study suggests that use of antimicrobial drugs to which the MRSA outbreak strains are resistant may be an important factor in perpetuating the outbreak. Moreover, this study confirmed the ecologic effect of antimicrobial drug use (i.e., current antimicrobial use) may have an effect on resistance in future patients. Although these results may not be generalized to other hospitals, they suggest new directions for control of MRSA, which has thus far proved difficult and expensive.

Antimicrobial Prophylaxis for Surgery: An Advisory Statement from the National Surgical Infection Prevention Project

In January 2003, leadership of the Medicare National Surgical Infection Prevention Project hosted the Surgical Infection Prevention Guideline Writers Workgroup (SIPGWW) meeting. The objectives were to review areas of agreement among the most-recently published guidelines for surgical antimicrobial prophylaxis, to address inconsistencies, and to discuss issues not currently addressed. The participants included authors from most of the groups that have published North American guidelines for antimicrobial prophylaxis, as well as authors from several specialty colleges. Nominal group process was used to draft a consensus paper that was widely circulated for comment. The consensus positions of SIPGWW include that infusion of the first antimicrobial dose should begin within 60 min before surgical incision and that prophylactic antimicrobials should be discontinued within 24 h after the end of surgery. This advisory statement provides an overview of other issues related to antimicrobial prophylaxis, including specific suggestions regarding antimicrobial selection.

Favorable impact of a multidisciplinary antibiotic management program conducted during 7 years

OBJECTIVE

To evaluate the impact of an interventional multidisciplinary antibiotic management program on expenditures for antibiotics and on the incidence of nosocomial infections caused by Clostridium difficile and antibiotic-resistant pathogens during 7 years.

DESIGN

Prospective study with comparison with preintervention trends.

SETTING

University-affiliated teaching hospital.

PATIENTS

All adult inpatients.

INTERVENTION

A multidisciplinary antibiotic management program to minimize the inappropriate use of third-generation cephalosporins was implemented in 1991. Its impact was evaluated prospectively. The incidence of nosocomial C. difficile and resistant Enterobacteriaceae infections as well as the rate of vancomycin-resistant enterococci (VRE) and methicillin-resistant Staphylococcus aureus (MRSA) were compared with those of National Nosocomial Infections Surveillance System hospitals of similar size.

RESULTS

Following implementation of the program, there was a 22% decrease in the use of parenteral broad-spectrum antibiotics (P < .0001) despite a 15% increase in acuity of patient care during the following 7 years. Concomitantly, there was a significant (P = .002) decrease in nosocomial infections caused by C. difficile and a significant (P = .02) decrease in nosocomial infections caused by resistant Enterobacteriaceae. The program also appeared to have a favorable impact on VRE rates without a sustained impact on MRSA rates.

CONCLUSION

These results suggest that an ongoing multidisciplinary antibiotic management program may have a sustained beneficial impact on both expenditures for antibiotics and the incidence of nosocomial infection by C. difficile and resistant bacterial pathogens.

Additional costs for preventing the spread of methicillin-resistant Staphylococcus aureus and a strategy for reducing these costs on a surgical ward

OBJECTIVE

To determine the added costs of hygienic measures (barrier precautions, isolation, and decontamination) required for MRSA carriers in German hospitals and possible strategies for cost reduction.

DESIGN

On a septic surgical ward caring for 35% of all MRSA cases in a university hospital (1,182 beds), additional costs for personnel time and materials were calculated and medical charts of all MRSA cases admitted to the ward during 1 year were analyzed retrospectively. Twelve of the ward's 13 beds were located in rooms with at least 2 beds.

PATIENTS

Four hundred ninety-eight MRSA carrier hospital-days (of 20 MRSA cases) could be assessed. All patients (80% men, 50% older than 74.5 years) had broken skin.

RESULTS

In 95% of the cases, microbiological findings suggested transmission of MRSA during the current or a previous stay on this ward. The study found total avoidable costs of approximately 142,794.01 euros in 1 year, averaging 371.95 euros for one MRSA patient hospital-day and 9,261.56 euros per MRSA case. The most expensive single measure was blocked beds in multibed rooms (305.75 euros/day), which accounted for 82% of the extra costs. Costs most likely were underestimated.

CONCLUSIONS

Daily additional case costs amounted to 96% of social security payments. Blocked beds in multibed rooms accounted for more than 80% of these excess costs. Isolation has been scientifically validated and is required by law in Germany. Building an adequate number of single-bed rooms should help prevent spread and would greatly lower the added costs of infection.

Role of healthcare workers in outbreaks of methicillin-resistant Staphylococcus aureus: a 10-year evaluation from a Dutch university hospital

BACKGROUND AND OBJECTIVE

The benefit of screening healthcare workers (HCWs) at risk for methicillin-resistant Staphylococcus aureus (MRSA) carriage and furloughing MRSA-positive HCWs to prevent spread to patients is controversial. We evaluated our MRSA program for HCWs between 1992 and 2002.

SETTING

A university medical center in The Netherlands, where methicillin resistance has been kept below 0.5% of all nosocomial S. aureus infections using active surveillance cultures and isolation of colonized patients.

DESIGN

HCWs caring for MRSA-positive patients or patients in foreign hospitals were screened for MRSA. MRSA-positive HCWs had additional cultures, temporary exclusion from patient-related work, assessment of risk factors for persisting carriage, decolonization therapy with mupirocin intranasally and chlorhexidine baths for skin and hair, and follow-up cultures.

RESULTS

Fifty-nine HCWs were colonized with MRSA. Seven of 840 screened employees contracted MRSA in foreign hospitals; 36 acquired MRSA after contact with MRSA-positive patients despite isolation precautions (attack rate per outbreak varied from less than 1% to 15%). Our hospital experienced 17 MRSA outbreaks, including 13 episodes in which HCWs were involved. HCWs were index cases of at least 4 outbreaks. In 8 outbreaks, HCWs acquired MRSA after caring for MRSA-positive patients despite isolation precautions.

CONCLUSION

Postexposure screening of HCWs allowed early detection of MRSA carriage and prevention of subsequent transmission to patients. Where the MRSA prevalence is higher, the role of HCWs may be greater. In such settings, an adapted version of our program could help prevent dissemination.

Community-acquired methicillin-resistant Staphylococcus aureus infection in Singapore is usually "healthcare associated"

OBJECTIVE

To assess the frequency of community-acquired methicillin-resistant Staphylococcus aureus (MRSA) infections.

SETTING

A teaching hospital in Singapore.

METHODS

Prospectively collected surveillance data were reviewed during a 1-year period to determine the extent and origin of community-acquired MRSA infections.

RESULTS

Whereas 32% of 383 MRSA infections were detected less than 48 hours after hospital admission and would, by convention, be classified as "community acquired," all but one of these were among patients who had been exposed to outpatient centers including dialysis or chemotherapy clinics, visiting nurses, community hospitals, or all three.

CONCLUSIONS

With health care increasingly being delivered in an outpatient setting, community-acquired MRSA infections are often acquired in hospital-related sites and most may be more accurately described as "healthcare acquired." Infection control measures need to move beyond the traditional paradigm of acute care hospitals to effectively control the spread of resistant pathogens.

Prevalence of and risk factors for colonization with methicillin-resistant Staphylococcus aureus in an outpatient clinic population

OBJECTIVES

To determine the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) colonization in an outpatient population and to identify risk factors for MRSA colonization.

DESIGN

Surveillance cultures were performed during outpatient visits to identify S. aureus colonization. A case-control study was performed to identify risk factors for MRSA colonization.

SETTING

Primary care internal medicine clinic.

PATIENTS

Adults presenting for non-acute primary care (N = 494).

RESULTS

S. aureus was isolated from 122 (24.7%) of the patients for whom cultures were performed. Methicillin-susceptible S. aureus was isolated from 107 (21.7%) of the patients, whereas MRSA was isolated from 15 (3.0%) of the patients. All MRSA isolates were resistant to multiple non-beta-lactam antimicrobial agents. In multivariate analyses, MRSA colonization was independently associated with admission to a nursing home (adjusted odds ratio [OR], 103; 95% confidence interval [CI95], 7 to 999) or hospital in the previous year, although the association with hospital admission was observed only among those without chronic illness (adjusted OR, 7.1; CI95, 1.3 to 38.1). In addition, MRSA colonization was associated with the presence of at least one underlying chronic illness, although this association was observed only among those who had not been hospitalized in the previous year (adjusted OR, 5.1; CI95, 1.2 to 21.9).

CONCLUSIONS

We found a low prevalence of MRSA colonization in an adult outpatient population. MRSA carriers most likely acquired the organism through contact with healthcare facilities rather than in the community. These data show that care must be taken when attributing MRSA colonization to the community if detected in outpatients or during the first 24 to 48 hours of hospitalization.

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.

Outbreak of invasive disease caused by methicillin-resistant Staphylococcus aureus in neonates and prevalence in the neonatal intensive care unit

OBJECTIVES

To describe an outbreak of severe invasive disease caused by methicillin-resistant Staphylococcus aureus (MRSA) and the epidemiology of MRSA in a neonatal intensive care unit during a 12-yr period from 1989 to 2001.

SETTING

A 40-bed, level III neonatal intensive care unit at a children's hospital that admits approximately 450 neonates each year from about 35 neighboring hospitals.

PATIENTS

All neonates infected or colonized with MRSA during the outbreak are described. All cases of MRSA infection or colonization in the neonatal intensive care unit from 1989 to 2001 were identified from the database maintained by the hospital epidemiology program.

RESULTS

During the outbreak, 12 neonates were infected or colonized with MRSA, 11 of whom had the epidemic strain. Seven of these 11 neonates had invasive disease, including bacteremia, meningitis, or urinary tract infection, and four neonates were colonized with the epidemic strain. This outbreak was difficult to control by routine epidemiologic measures, and additional control measures, including closing the neonatal intensive care unit to new admissions and treating all infants with intranasal mupirocin, were implemented. Since the outbreak, the prevalence of MRSA in the neonatal intensive care unit has remained low.

CONCLUSIONS

MRSA outbreaks in neonatal intensive care units can be prolonged. Aggressive infection-control measures are often necessary to terminate these outbreaks. Such efforts are essential because MRSA infections in premature neonates can cause significant morbidity and mortality.

The clinical relevance of microbiology in acute and chronic wounds

PURPOSE

To improve clinical practice and the quality of patient care by providing a learning opportunity that enhances the participant's understanding of how wound microbiology affects healing.

TARGET AUDIENCE

This CME/CE activity is intended for physicians and nurses with an interest in interpreting the role of microorganisms in wound healing.

OBJECTIVES

At the conclusion of this course, participants should be able to: 1. Identify the microbiology of acute and chronic wounds, risk factors for infection, and advantages and disadvantages of wound culturing. 2. Identify methods of debridement and wounds for which they are appropriate. 3. Identify systemic antibiotic treatment options for acute and chronic wound infections.

Rapid detection of methicillin-resistant Staphylococcus aureus directly from sterile or nonsterile clinical samples by a new molecular assay

A rapid procedure was developed for detection and identification of methicillin-resistant Staphylococcus aureus (MRSA) directly from sterile sites or mixed flora samples (e.g., nose or inguinal swabs). After a rapid conditioning of samples, the method consists of two main steps: (i) immunomagnetic enrichment in S. aureus and (ii) amplification-detection profile on DNA extracts using multiplex quantitative PCR (5'-exonuclease qPCR, TaqMan). The triplex qPCR assay measures simultaneously the following targets: (i) mecA gene, conferring methicillin resistance, common to both S. aureus and Staphylococcus epidermidis; (ii) femA gene from S. aureus; and (iii) femA gene from S. epidermidis. This quantitative approach allows discrimination of the origin of the measured mecA signal. qPCR data were calibrated using two reference strains (MRSA and methicillin-resistant S. epidermidis) processed in parallel to clinical samples. This 96-well format assay allowed analysis of 30 swab samples per run and detection of the presence of MRSA with exquisite sensitivity compared to optimal culture-based techniques. The complete protocol may provide results in less than 6 h (while standard procedure needs 2 to 3 days), thus allowing prompt and cost-effective implementation of contact precautions.