Eradication of Methicillin-ResistantStaphylococcus AureusFrom a Neonatal Intensive Care Unit by Active Surveillance and Aggressive Infection Control Measures

Seven-year experience with a surveillance program to reduce methicillin-resistant Staphylococcus aureus colonization in a neonatal intensive care unit

OBJECTIVES

The objectives of this study were to determine the incidence rates of neonatal methicillin-resistant Staphylococcus aureus colonization and infection after the implementation of a NICU methicillin-resistant S aureus surveillance and isolation program and to describe the characteristics of infants with methicillin-resistant S aureus colonization and invasive disease.

METHODS

From August 2000 through August 2007, all infants admitted to the study NICU were screened for methicillin-resistant S aureus colonization with weekly nasal/rectal swabs; colonized or infected infants were isolated and cared for as a cohort. The annual incidence rates of methicillin-resistant S aureus colonization and infection were monitored, and characteristics of methicillin-resistant S aureus-colonized and -infected infants were compared. Data were collected from infant, maternal, and hospital laboratory records.

RESULTS

During the study period, 7997 infants were admitted to the NICU and 102 methicillin-resistant S aureus-colonized or -infected infants (1.3%) were identified. The incidence of methicillin-resistant S aureus decreased progressively from 1.79 cases per 1000 patient-days in 2000 to 0.15 cases per 1000 patient-days in 2005, but the incidence then increased to 1.26 cases per 1000 patient-days in 2007. Fifteen of the 102 case infants (14.7%) had invasive infections; no significant differences between infected and colonized infants were identified. Methicillin-resistant S aureus isolates with 14 different antibiograms were found during the study period. There was a shift from isolates predominantly likely to be hospital-associated in 2000-2004 to those likely to be community-associated in 2006-2007.

CONCLUSIONS

A continuous program of weekly methicillin-resistant S aureus surveillance cultures and isolation of affected infants was associated with a variable incidence of methicillin-resistant S aureus colonization over a 7-year study period. Methicillin-resistant S aureus was not eradicated from this tertiary-care NICU, and our data suggest that infants were colonized by multiple different methicillin-resistant S aureus strains during the study period.

Eradication of methicillin-resistant Staphylococcus aureus in a neonatal intensive care unit: which measures for which success?

BACKGROUND

Various strategies for controlling methicillin-resistant Staphylococcus aureus (MRSA) outbreaks in neonatal intensive care units (NICUs) have been tried, with varying levels of success. We report a MRSA outbreak occurring between April 2004 and August 2007 in a 24-bed NICU in a large university hospital. We describe the difficulties involved in implementing measures to control the MRSA outbreak and the possible contribution of each measure.

METHODS

Cases were defined as neonates with MRSA obtained from either clinical cultures or surveillance cultures (from the anterior nares). Systematic screening of neonates for colonization was performed only between February and December 2005. Successive control strategies included barrier precaution and isolation in individual rooms, mupirocine ointment for neonates and health care workers, cohort isolation, hand hygiene observation, and staff training.

RESULTS

During the routine surveillance culture period (February to December 2005; 48 weeks), 46 neonates were found to be positive for MRSA and were treated with mupirocin. After December 2005, the outbreak was controlled, but the ongoing spread was not eradicated; 9 sporadic MRSA cases were detected by clinical culture up to August 2007.

CONCLUSION

The widespread use of mupirocine in staff and patients did not control the outbreak and is not recommended. The later control appeared to coincide with increased hand hygiene audits and training for staff, along with appropriate cohort isolation of neonates and cohort nursing.

Multicenter evaluation of the Cepheid Xpert methicillin-resistant Staphylococcus aureus (MRSA) test as a rapid screening method for detection of MRSA in nares

The first U.S. multicenter clinical trial to assess the performance of the Cepheid Xpert MRSA assay (Xpert MRSA) was conducted. The assay is a qualitative test designed for the rapid detection of methicillin-resistant Staphylococcus aureus (MRSA) directly from nares swabs. This novel test combines integrated nucleic acid extraction and automated real-time PCR for the detection of a MRSA-specific signature sequence. A total of 1,077 nares specimens were collected from seven geographically distinct health care sites across the United States with prevalence rates ranging from 5.2% to 44%. Nares specimens were tested by (i) the Xpert MRSA assay, (ii) direct culture on CHROMagar MRSA medium (direct CM culture), and (iii) broth-enriched culture (Trypticase soy broth with 6.5% sodium chloride) followed by plating onto CHROMagar MRSA medium (broth-enriched CM culture). When direct CM culture was designated the reference method, the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the Xpert MRSA assay were 94.3%, 93.2%, 73.0%, and 98.8%, respectively. When broth-enriched CM culture was used as the reference method, the clinical sensitivity, specificity, PPV, and NPV of the Xpert MRSA assay were 86.3%, 94.9%, 80.5%, and 96.6%, respectively. The BD GeneOhm MRSA (BDGO) assay was performed as a comparative molecular method. No statistical performance differences were observed between the Xpert MRSA and BDGO assays when they were compared to culture methods. From this large-scale, multicenter clinical comparison, we conclude that the Xpert MRSA assay is a simple, rapid, and accurate method for performing active surveillance for MRSA in a variety of health care populations.

Consideration to culture health care workers related to increased methicillin-resistant Staphylococcus aureus activity in a neonatal intensive care unit

BACKGROUND

For 2 consecutive years, a care level III neonatal intensive care unit (NICU) in a 700-bed health care facility experienced an increase in health care-associated methicillin-resistant Staphylococcus aureus (MRSA). To decrease transmission, standard infection prevention techniques, active surveillance cultures, and deoxyribonucleic acid typing were done. After control was achieved, members of the organization outside of infection prevention and control requested health care worker (HCW) screening for MRSA, believing that it would decrease chances of future transmission.

METHODS

To develop effective tools to communicate with organization members: (1) questions that must be resolved before HCW screening can be done accurately, (2) operational requirements for HCW screening, and (3) a "trigger point" for HCW screening should MRSA activity increase in the future.

RESULTS

Developed tools to determine when MRSA screening of HCWs is warranted and for the preparation process when MRSA screening is necessary. Without performing HCW screening in the NICU, there were no health care-associated infections with MRSA for 20 months or colonization for 5 months.

CONCLUSION

Proactive consideration of HCW screening can be achieved by designing and implementing tools to illustrate the complexity of the HCW screening process and by defining a "trigger point" for HCW culturing if needed for MRSA control. Decreasing MRSA transmission in this NICU was accomplished without culturing health care workers.

Methicillin-resistant Staphylococcus aureus outbreak in an intensive care nursery: potential for interinstitutional spread

BACKGROUND

After surveillance surveys documented the absence of methicillin-resistant Staphylococcus aureus (MRSA) in our intensive care nursery, an outbreak of MRSA infection occurred there during a 7-month period in 2005.

METHODS

Control measures included reinforcement of hand hygiene and contact precautions procedures. Active surveillance cultures were obtained on all neonates, including interinstitutional transfers. A cohort unit was dedicated exclusively for neonates with MRSA. Pulsed-field gel electrophoresis was performed on isolates to determine relatedness. We surveyed transferring hospitals to evaluate MRSA activity and surveillance practices in their nurseries.

RESULTS

Twenty-five neonates were colonized with MRSA; 9 of these had clinical infections. Isolates from 18 of 21 neonates from this outbreak and 4 neonates from a previous cluster were identical, including 1 isolate obtained upon transfer from another institution. Admission and discharge logs from a 9-month period showed that 127 of 460 admissions (27.6%) were admitted from 34 hospitals, and 247 of 460 (53.7%) were discharged to 32 hospitals. Among 30 transferring hospitals responding to our survey, MRSA activity occurred in 2 of 28 (7%) level 1 nurseries, 4 of 11 (36%) level 2 nurseries and 6 of 10 (60%) level 3 nurseries. Nine of the 30 hospitals (30%) performed some active surveillance.

CONCLUSIONS

Interinstitutional transfer can play a role in the initiation and propagation of MRSA outbreaks in neonatal nurseries. The burden of MRSA in area nurseries and the rate of transfers affect the potential for interhospital spread of MRSA and may justify changes in policy regarding surveillance for MRSA and communication between hospitals.

Legislative mandates for use of active surveillance cultures to screen for methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci: Position statement from the Joint SHEA and APIC Task Force

Legislation aimed at controlling antimicrobial-resistant pathogens through the use of active surveillance cultures to screen hospitalized patients has been introduced in at least 2 US states. In response to the proposed legislation, the Society for Healthcare Epidemiology of America (SHEA) and the Association for Professionals in Infection Control and Epidemiology, Inc., (APIC) have developed this joint position statement. Both organizations are dedicated to combating health care-associated infections with a wide array of methods, including the use of active surveillance cultures in appropriate circumstances. This position statement reviews the proposed legislation and the rationale for use of active surveillance cultures, examines the scientific evidence supporting the use of this strategy, and discusses a number of unresolved issues surrounding legislation mandating use of active surveillance cultures. The following 5 consensus points are offered. (1) Although reducing the burden of antimicrobial-resistant pathogens, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE), is of preeminent importance, the APIC and the SHEA do not support legislation to mandate use of active surveillance cultures to screen for MRSA, VRE, or other antimicrobial-resistant pathogens. (2) The SHEA and the APIC support the continued development, validation, and application of efficacious and cost-effective strategies for the prevention of infections caused by MRSA, VRE, and other antimicrobial-resistant and antimicrobial-susceptible pathogens. (3) The APIC and the SHEA welcome efforts by health care consumers, together with private, local, state, and federal policy makers, to focus attention on and formulate solutions for the growing problem of antimicrobial resistance and health care-associated infections. (4) The SHEA and the APIC support ongoing additional research to determine and optimize the appropriateness, utility, feasibility, and cost-effectiveness of using active surveillance cultures to screen both lower-risk and high-risk populations. (5) The APIC and the SHEA support stronger collaboration between state and local public health authorities and institutional infection prevention and control experts.

Prevention of catheter-related bloodstream infections in the neonatal intensive care setting

Nosocomial infection causes substantial morbidity and mortality among neonates treated in the neonatal intensive care setting. Colonization and subsequent infection of central venous catheters leading to catheter-related bloodstream infection is among the most common causes of nosocomial sepsis in this patient population. Prevention of catheter-related bloodstream infection is a major challenge and numerous strategies have been attempted in this context with varying success. Given the dynamic epidemiology of nosocomial infection among neonates and the emergence of antimicrobial resistance, novel prevention strategies are urgently required.

Clinical outcomes in methicillin-resistant Staphylococcus aureus-colonized neonates in the neonatal intensive care unit

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) colonization can persist for prolonged periods, and patient-related factors are associated with persistent carriage in adults. However, such knowledge is lacking among neonates.

OBJECTIVES

To better understand the outcome of MRSA-colonized neonates in the neonatal intensive care unit (NICU), we prospectively followed all colonized neonates until decolonization over 39 months and determined the incidence, duration of colonization, clinical outcomes and risk factors associated with prolonged carriage of MRSA.

METHODS

Nasal and inguinal cultures were obtained from all newly admitted neonates following an outbreak of MRSA. Weekly and 1-2 monthly cultures were obtained from all hospitalized and discharged neonates colonized with MRSA, respectively, until 2 consecutive cultures were negative.

RESULTS

152 of 1,456 (10.4%) neonates became colonized. The mean time to acquire MRSA colonization was 17.1 +/- 40.7 (range 1-471) days. The median time to decolonization was 36 days. About 20% of decolonized patients had been colonized for a prolonged period of >or=160 days. 47.5% of colonized patients were sent home colonized, and none with prolonged carriage developed MRSA-related infections in the following 6 months in contrast to 6 infants (3.9%) who developed MRSA sepsis during hospitalization. The only risk factor associated with prolonged carriage was the concurrent colonization of both the inguinal and nasal areas on admission.

CONCLUSION

Nearly all neonates with acquired colonization became decolonized either prior to or after discharge from NICU. A significant percentage failed to decolonize prior to hospital discharge, but almost all decolonized by 30 months in the community without evidence of systemic or local infections.

Costs of hospital-acquired methicillin-resistant Staphylococcus aureus (MRSA) and its control

For most countries badly affected by methicillin-resistant Staphylococcus aureus (MRSA) there have been many years of debate about its relative virulence compared with methicillin-susceptible S. aureus (MSSA) and whether it could be controlled. Now that it is endemic in the majority of hospitals around the world, it is clear that it is at least as virulent as MSSA and is an additional burden of healthcare-acquired infection. There is increasing evidence that, despite this endemicity, control efforts can be successful, although they are often perceived as expensive. In reality, there is a large body of consistent evidence that control is highly cost effective, particularly in the context of the huge societal costs of MRSA and the future ever-greater threats that it poses.

Optimal surveillance culture sites for detection of methicillin-resistant Staphylococcus aureus in newborns

We describe two outbreaks among newborns, one caused by community-associated methicillin-resistant Staphylococcus aureus (MRSA) and the other by hospital-associated MRSA. The umbilicus, rectum, and nares were tested for colonization. We found that no single body site had optimal sensitivity when tested alone. The combination of umbilical and nasal swabs achieved a sensitivity of >90%.

[Staphylococcus aureus infections: new challenges from an old pathogen]

Staphylococcus aureus is a versatile organism with several virulent characteristics and resistance mechanisms at its disposal. It is also a significant cause of a wide range of infectious diseases in humans. S. aureus often causes life-threatening deep seated infections like bacteremia, endocarditis and pneumonia. While traditionally confined mostly to the hospital setting, methicillin-resistant S. aureus (MRSA) is now rapidly becoming rampant in the community. Community-acquired MRSA is particularly significant because of its potential for unchecked spread within households and its propensity for causing serious skin and pulmonary infections. Because of the unfavorable outcome of many MRSA infections with the standard glycopeptide therapy, new antimicrobial agents belonging to various classes have been introduced and have been evaluated in clinical trials for their efficacy in treating resistant staphylococcal infections. A number of preventive strategies have also been suggested to contain the spread of such infections. In this review, we address the recent changes in the epidemiology of S. aureus and their impact on the clinical manifestations and management of serious infections. We also discuss new treatment modalities for MRSA infections and emphasize the importance of preventive approaches.