Epidemiology of methicillin-resistant Staphylococcus aureus colonization in a surgical intensive care unit.

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) is a cause of healthcare-associated infections among surgical intensive care unit (ICU) patients, though transmission dynamics are unclear. OBJECTIVE: To determine the prevalence of MRSA nasal colonization at ICU admission, to identify associated independent risk factors, to determine the value of these factors in active surveillance, and to determine the incidence of and risk factors associated with MRSA acquisition. DESIGN: Prospective cohort study. SETTING: Surgical ICU at a teaching hospital. PATIENTS: All patients admitted to the surgical ICU. RESULTS: Active surveillance for MRSA by nasal culture was performed at ICU admission during a 15-month period. Patients who stayed in the ICU for more than 48 hours had nasal cultures performed weekly and at discharge from the ICU, and clinical data were collected prospectively. Of 1,469 patients, 122 (8%) were colonized with MRSA at admission; 75 (61%) were identified by surveillance alone. Among 775 patients who stayed in the ICU for more than 48 hours, risk factors for MRSA colonization at admission included the following: hospital admission in the past year (1-2 admissions: adjusted odds ratio [aOR], 2.60 [95% confidence interval {CI}, 1.47-4.60]; more than 2 admissions: aOR, 3.56 [95% CI, 1.72-7.40]), a hospital stay of 5 days or more prior to ICU admission (aOR, 2.54 [95% CI, 1.49-4.32]), chronic obstructive pulmonary disease (aOR, 2.16 [95% CI, 1.17-3.96]), diabetes mellitus (aOR, 1.87 [95% CI, 1.10-3.19]), and isolation of MRSA in the past 6 months (aOR, 8.18 [95% CI, 3.38-19.79]). Sixty-nine (10%) of 670 initially MRSA-negative patients acquired MRSA in the ICU (corresponding to 10.7 cases per 1,000 ICU-days at risk). Risk factors for MRSA acquisition included tracheostomy in the ICU (aOR, 2.18 [95% CI, 1.13-4.20]); decubitus ulcer (aOR, 1.72 [95% CI, 0.97-3.06]), and receipt of enteral nutrition via nasoenteric tube (aOR, 3.73 [95% CI, 1.86-7.51]), percutaneous tube (aOR, 2.35 [95% CI, 0.74-7.49]), or both (aOR, 3.33 [95% CI, 1.13-9.77]). CONCLUSIONS: Active surveillance detected a sizable proportion of MRSA-colonized patients not identified by clinical culture. MRSA colonization on admission was associated with recent healthcare contact and underlying disease. Acquisition was associated with potentially modifiable processes of care.     

An outbreak of methicillin-resistant Staphylococcus aureus in a neonatal intensive care unit.

OBJECTIVE: To describe the epidemiologic and molecular investigations that successfully contained an outbreak of methicillin-resistant Staphylococcus aureus (MRSA) in a neonatal intensive care unit (NICU). DESIGN: Isolates of MRSA were typed by pulsed-field gel electrophoresis (PFGE) and S. aureus protein A (spa). SETTING: A level III-IV, 45-bed NICU located in a children's hospital within a medical center. PATIENTS: Incident cases had MRSA isolated from clinical cultures (eg, blood) or surveillance cultures (ie, anterior nares). INTERVENTIONS: Infected and colonized infants were placed on contact precautions, cohorted, and treated with mupirocin. Surveillance cultures were performed for healthcare workers (HCWs). Colonized HCWs were treated with topical mupirocin and hexachlorophene showers. RESULTS: From January to March 2001, the outbreak strain of MRSA, PFGE clone B, was harbored by 13 infants. Three (1.3%) of 235 HCWs were colonized with MRSA. Two HCWs, who rotated between the adult and the pediatric facility, harbored clone C. One HCW, who exclusively worked in the children's hospital, was colonized with clone B. From January 1999 to November 2000, 22 patients hospitalized in the adult facility were infected or colonized with clone B. Spa typing and PFGE yielded concordant results. PFGE clone B was identified as spa type 16, associated with outbreaks in Brazil and Hungary. CONCLUSIONS: A possible route of MRSA transmission was elucidated by molecular typing. MRSA appears to have been transferred from our adult facility to our pediatric facility by a rotating HCW. Spa typing allowed comparison of our institution's MRSA strains with previously characterized outbreak clones.     

Father-to-infant transmission of community-acquired methicillin-resistant Staphylococcus aureus in a neonatal intensive care unit.

Methicillin-resistant Staphylococcus aureus (MRSA) is increasingly being recognized as a cause of community-acquired infection. Its transmission in neonatal intensive care units (NICUs) has reportedly been linked to a few cases of community-acquired MRSA (CA-MRSA) infection. Here, I describe a case of CA-MRSA transmission from a father to his child in a NICU. Recognition that CA-MRSA may be transmitted in a hospital setting raises important issues for MRSA infection control and treatment options.     

Implication of a healthcare worker with chronic skin disease in the transmission of an epidemic strain of methicillin-resistant Staphylococcus aureus in a pediatric intensive care unit.

This outbreak of colonization of neonates in a 10-bed pediatric intensive care unit illustrates the probable role of a healthcare worker (HCW) in the transmission of methicillin-resistant Staphylococcus aureus, despite good hygienic practices. It raises the issue of preventive exclusion of HCWs affected by chronic skin disease from high-risk units.     

重症监护室患者鼻腔金黄色葡萄球菌定植与医院感染的关系

目的分析重症监护室(ICU)患者鼻腔定植金黄色葡萄球菌(SA)与院内感染的关系和安尔碘III鼻腔去定植治疗效果。方法对入院患者行鼻拭子细菌学检测,并观察所有患者医院感染的发生情况。将有SA定植者分为对照组和治疗组,对照组给予常规治疗和护理,治疗组在此基础上再给予安尔碘III鼻腔去定植治疗。观察两组患者鼻腔SA清除率和医院感染的发生情况。结果共751例患者入选本研究,108例发生医院感染,发生率为14.38%。SA鼻腔定植85例(11.3%),其中耐甲氧西林金黄色葡萄球菌(MRSA)定植者33例(4.4%),MRSA定植患者入院后医院感染发生率为51.5%,明显高于其他类型细菌定植者(P0.05)。治疗组鼻腔SA清除率为81.4%,明显高于对照组的42.8%(P0.05);治疗组医院感染发生率为16.3%,明显低于对照组的40.5%(P0.05);MRSA定植患者经去定植治疗以后,医院感染发生率为25.0%,明显低于对照组的76.5%(P0.05)。结论 ICU患者中鼻腔MRSA定植者医院感染发生率明显增高,安尔碘III去定植治疗可以提高鼻腔SA清除率,降低医院感染的发生率。     

Management of outbreaks of methicillin-resistant Staphylococcus aureus infection in the neonatal intensive care unit: a consensus statement.

OBJECTIVE: In 2002, the Chicago Department of Public Health (CDPH; Chicago, Illinois) convened the Chicago-Area Neonatal MRSA Working Group (CANMWG) to discuss and compare approaches aimed at control of methicillin-resistant Staphylococcus aureus (MRSA) in neonatal intensive care units (NICUs). To better understand these issues on a regional level, the CDPH and the Evanston Department of Health and Human Services (EDHHS; Evanston, Illinois) began an investigation. DESIGN: Survey to collect demographic, clinical, microbiologic, and epidemiologic data on individual cases and clusters of MRSA infection; an additional survey collected data on infection control practices. SETTING: Level III NICUs at Chicago-area hospitals. PARTICIPANTS: Neonates and healthcare workers associated with the level III NICUs. METHODS: From June 2001 through September 2002, the participating hospitals reported all clusters of MRSA infection in their respective level III NICUs to the CDPH and the EDHHS. RESULTS: Thirteen clusters of MRSA infection were detected in level III NICUs, and 149 MRSA-positive infants were reported. Infection control surveys showed that hospitals took different approaches for controlling MRSA colonization and infection in NICUs. CONCLUSION: The CANMWG developed recommendations for the prevention and control of MRSA colonization and infection in the NICU and agreed that recommendations should expand to include future data generated by further studies. Continuing partnerships between hospital infection control personnel and public health professionals will be crucial in honing appropriate guidelines for effective approaches to the management and control of MRSA colonization and infection in NICUs.     

Acquisition of methicillin-resistant Staphylococcus aureus in a large intensive care unit.

OBJECTIVES: To determine the prevalence of MRSA colonization on admission to the ICU and the incidence of MRSA colonization in the ICU. DESIGN: Prospective cohort study. SETTING: University hospital. PARTICIPANTS: Patients admitted to the ICU in 2000-2001. METHODS: Patients were screened for MRSA with nose, throat, groin, and axilla swabs on admission and discharge. MRSA acquisition was defined as a negative admission screen and a positive discharge screen. Risk factors analyzed included previous wards/current unit, gender, age, and length of stay prior to and in the ICU. Univariate and multivariate analyses were performed using logistic regression. RESULTS: Of screened patients, 6.8% were MRSA colonized on admission to the ICU. Some patients (11.4%) became newly colonized during their stay in the ICU. Factors that remained significant in the multivariate analysis of MRSA colonization on admission were previous admission to various wards and length of stay prior to ICU admission of more than 3 days. In the multivariate analysis of MRSA acquisition in the ICU, being a trauma patient and length of stay in the ICU greater than 2 days remained significant Thirty-six percent of patients had both admission and discharge swabs taken.This percentage increased in the presence of a supervisory nurse. CONCLUSION: Significant acquisition of MRSA occurs in the ICU of our hospital, with trauma patients at increased risk. Patients who had been on the cardiothoracic ward prior to the ICU had a lower risk of MRSA colonization on admission. Presence of a supervisory nurse improved compliance with screening     

Transmission of methicillin-resistant Staphylococcus aureus in the neonatal intensive care unit from a patient with community-acquired disease.

Methicillin-resistant Staphylococcus aureus (MRSA) has traditionally been a nosocomial pathogen. However, several recent studies have noted community-acquired MRSA among young, healthy patients with no risk factors or healthcare system exposure. We report the transmission of a strain of community-acquired MRSA in our neonatal intensive care unit.     

Eradication of methicillin-resistant Staphylococcus aureus from a neonatal intensive care unit by active surveillance and aggressive infection control measures.

OBJECTIVES: To describe an outbreak of hospital-acquired MRSA in a NICU and to identify the risk factors for, outcomes of, and interventions that eliminated it. SETTING: An 18-bed, level III-IV NICU in a community hospital. METHODS: Interventions to control MRSA included active surveillance, aggressive contact isolation, and cohorting and de-colonization of infants and HCWs with MRSA. A case-control study was performed to compare infants with and without MRSA. RESULTS: A cluster of 6 cases of MRSA infection between September and October 2001 represented an increased attack rate of 21.2% compared with 5.3% in the previous months. Active surveillance identified unsuspected MRSA colonization in 6 (21.4%) of 28 patients and 6 (5.5%) of 110 HCWs screened. They were all successfully decolonized. There was an increased risk of MRSA colonization and infection among infants with low birth weight or younger gestational age. Multiple gestation was associated with an increased risk of colonization (OR, 37.5; CI95, 3.9-363.1) and infection (OR, 5.36; CI95, 1.37-20.96). Gavage feeding (OR, 10.33; CI95, 1.28-83.37) and intubation (OR, 5.97; CI95, 1.22-29.31) were associated with increased risk of infection. Infants with MRSA infection had a significantly longer hospital stay than infants without MRSA (51.83 vs 21.46 days; P = .003). Rep-PCR with mec typing and PVL analysis confirmed the presence of a single common strain of hospital-acquired MRSA. CONCLUSION: Active surveillance, aggressive implementation of contact isolation, cohorting, and decolonization effectively eradicated MRSA from the NICU for 2 1/2 years following the outbreak.     

Methicillin-resistant Staphylococcus aureus in neonatal intensive care unit

A neonatal intensive care unit outbreak was caused by a strain of methicillin-resistant Staphylococcus aureus previously found in the community (ST45-MRSA-IV). Fifteen infected neonates were identified, 2 of whom died. This outbreak illustrates how a rare community pathogen can rapidly spread through nosocomial transmission.     

Outbreak of Serratia marcescens infection in a neonatal intensive care unit.

We report an outbreak of Serratia marcescens infection in the neonatal intensive care unit of a community hospital. The outbreak involved eight neonates, (five infected and three colonized), one of whom died. Pulsed-field gel electrophoresis confirmed that all isolates were identical strains. Cohorting and isolation of the infected neonates helped to control the outbreak. No environmental source of infection was found.     

Use of stochastic epidemic modeling to quantify transmission rates of colonization with methicillin-resistant Staphylococcus aureus in an intensive care unit.

OBJECTIVE: To consider statistical methods for estimating transmission rates for colonization of patients with methicillin-resistant Staphylococcus aureus (MRSA) in an intensive care unit (ICU) from three different sources: background contamination, non-isolated patients, and isolated patients. METHODS: We developed statistical methods that allowed for the analysis of interval-censored, routine surveillance data and extended the general epidemic model for the flow of patients through the ICU. RESULTS: Within this ICU, the rate of transmission to susceptible patients from a background source of MRSA (0.0092 case per day; 95% confidence interval [CI95], 0.0062-0.0126) is approximately double the rate of transmission from a non-isolated patient (0.0052 case per day; CI95, 0.0013-0.0096) and six times the rate of transmission from an isolated patient (0.0015 case per day; CI95, 0.0001-0.0043). We used the methodology to investigate whether transmission rates vary with workload. CONCLUSION: Our methodology has general application to infection by and transmission of pathogens in a hospital setting and is appropriate for quantifying the effect of infection control interventions.     

Duration of colonization with methicillin-resistant Staphylococcus aureus among patients in the intensive care unit: implications for intervention.

OBJECTIVES: To determine the duration of methicillin-resistant Staphylococcus aureus (MRSA) colonization or infection before entry and during hospitalization in the intensive care unit (ICU) and the characteristics of patients who tested positive for MRSA. DESIGN: Prospective observational cohort survey. SETTING: A combined medical and coronary care ICU with 16 single-bed rooms in a 427-bed tertiary care Veteran Affairs Medical Center. PATIENTS: A total of 720 ICU patients associated with 845 ICU admissions were followed up for the detection of MRSA from January 13, 2003, to October 12, 2003. MRSA colonization was detected in patients by using active surveillance cultures (ASCs) of nasal swab specimens obtained within 48 hours of ICU entry and 3 times weekly thereafter. The duration of colonization during ICU stay and before ICU entry was calculated after a review of surveillance culture results, clinical culture results, and medical history. RESULTS: Ninety-three (11.0%) of 845 ICU admissions involved patients who were colonized with MRSA at the time of ICU entry, and 21 admissions (2.5%) involved patients who acquired MRSA during ICU stay. ASCs were positive for MRSA in 84 (73.6%) of the 114 admissions associated with MRSA positivity and were the sole means of identifying MRSA in 50 cases (43.8%). More than half of the MRSA-associated admissions involved patients who were transferred from hospital wards. The total bed-days of care for 38 admissions involving patients who tested positive for MRSA before ICU entry (1131 days) was nearly 20% higher than the total bed-days of care for all admissions associated with MRSA positivity (970 days). Admissions involving MRSA-positive patients were associated with a longer length of hospitalization before ICU entry (P < .001), longer length of ICU stay (P < .001), longer overall length of hospitalization (P < .001), and greater inpatient mortality than admissions involving MRSA-negative patients (P < .001). A total of 22.8% of all bed-care days were dedicated to MRSA-positive patients in the ICU, and 55 (48.2%) of 114 admissions associated with MRSA positivity involved patients who were colonized for the duration of their ICU stay. CONCLUSIONS: In our unit, ASCs were an effective means to identify MRSA colonization among patients admitted to the ICU. Unfortunately, the majority of identified patients had long durations of stay in our own hospital before ICU entry, with prolonged MRSA colonization. Enhanced efforts to control MRSA will have to account for the prevalence of MRSA within hospital wards and to direct control efforts at these patients in the future.     

An outbreak of methicillin-resistant Staphylococcus aureus surgical-site infections initiated by a healthcare worker with chronic sinusitis.

An investigation was performed following two methicillin-resistant Staphylococcus aureus surgical-site infections in a 946-bed French general hospital. The investigation revealed that the outbreak involved 7 patients in 2 surgical wards and that infections were probably contracted in the operating theater from a healthcare worker suffering from chronic sinusitis.     

An outbreak of infection with a gentamicin and methicillin-resistant Staphylococcus aureus in a neonatal unit

A strain of Staphylococcus aureus resistant to gentamicin and methicillin and many other antibiotics caused an outbreak of infection in a neonatal unit. Eleven infants and three staff members became colonized with the organism. One of the staff suffered from psoriasis. Two infants developed septicaemia following infections of intravenous drip sites and one of these subsequently died. The strain was eliminated by closure and thorough cleaning of the unit and the transfer of infected or colonised patients to an isolation ward specially opened for this purpose.     

An outbreak of infection due to Staphylococcus aureus phage type 52 in a neonatal intensive care unit.

An outbreak of infection due to Staphylococcus aureus phage-type 52, resistant only to penicillin, occurred in children's wards primarily in a neonatal intensive care unit. The outbreak involved 86 infants; the majority presented with conjunctivitis, wound infections, boils, omphalitis and otitis externa. Seven per cent of these infants (six of 86) also had septicaemia. In addition, 6% (five of 86) were colonized by this phage type and the most common site of carriage was the umbilicus. The outbreak was contained by eradication of nasal carriage among the staff members and also by standard infection control measures.