Risk factors for colonization with extended-spectrum beta-lactamase-producing bacteria and intensive care unit admission

Extended-spectrum beta-lactamase (ESBL)-producing bacteria are emerging pathogens. To analyze risk factors for colonization with ESBL-producing bacteria at intensive care unit (ICU) admission, we conducted a prospective study of a 3.5-year cohort of patients admitted to medical and surgical ICUs at the University of Maryland Medical Center. Over the study period, admission cultures were obtained from 5,209 patients. Of these, 117 were colonized with ESBL-producing Escherichia coli and Klebsiella spp., and 29 (25%) had a subsequent ESBL-positive clinical culture. Multivariable analysis showed the following to be statistically associated with ESBL colonization at admission: piperacillin-tazobactam (odds ratio [OR] 2.05, 95% confidence interval [CI] 1.36-3.10), vancomycin (OR 2.11, 95% CI 1.34-3.31), age > 60 years (OR 1.79, 95% CI 1.24-2.60), and chronic disease score (OR 1.15; 95% CI 1.04-1.27). Coexisting conditions and previous antimicrobial drug exposure are thus predictive of colonization, and a large percentage of these patients have subsequent positive clinical cultures for ESBL-producing bacteria.     

Co-carriage rates of vancomycin-resistant Enterococcus and extended-spectrum beta-lactamase-producing bacteria among a cohort of intensive care unit patients: implications for an active surveillance program.

OBJECTIVE: To assess the co-colonization rates of extended-spectrum beta-lactamase (ESBL)-producing bacteria and vancomycin-resistant Enterococcus (VRE) obtained on active surveillance cultures. DESIGN: Prospective cohort study. SETTING: Medical and surgical intensive care units (ICUs) of a tertiary-care hospital. PATIENTS: Patients admitted between September 2001 and November 2002 to the medical and surgical ICUs at the University of Maryland Medical System had active surveillance perirectal cultures performed. Samples were concurrently processed for VRE and ESBL-producing bacteria. RESULTS: Of 1,362 patients who had active surveillance cultures on admission, 136 (10%) were colonized with VRE. Among these, 15 (positive predictive value, 11%) were co-colonized with ESBL. Among the 1,226 who were VRE negative, 1,209 were also ESBL negative (negative predictive value, 99%). Among the 1,362 who had active surveillance cultures on admission, 32 (2%) were colonized with ESBL. Among these, 15 (47%) were co-colonized with VRE. Of the 32 patients colonized with ESBL, 10 (31%) had positive clinical cultures for ESBL on the same hospital admission. For these 10 patients, the surveillance cultures were positive an average of 2.7 days earlier than the clinical cultures. CONCLUSIONS: Patients who are colonized with VRE can also be co-colonized with other antibiotic-resistant bacteria such as ESBL-producing bacteria. Our study is the first to measure co-colonization rates of VRE and ESBL-producing bacteria. Isolating VRE-colonized patients would isolate 47% of the ESBL-colonized patients without the need for further testing. Hence, active surveillance for VRE should also theoretically diminish the amount of patient-to-patient transmission of ESBL-producing bacteria.     

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.     

Regional trends in multidrug-resistant infections in German intensive care units: a real-time model for epidemiological monitoring and analysis

A new surveillance module for multidrug-resistant (MDR) bacteria was added to the intensive care component of the German Nosocomial Infection Surveillance System. Participating intensive care units (ICUs) report data on all patients colonised or infected with meticillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE) and extended-spectrum β-lactamase-producing Escherichia coli and Klebsiella pneumoniae (ESBL-EC/KP). To determine the regional distribution of MRSA, VRE and ESBL-EC/KP in Germany, incidence densities (IDs) of these bacteria per 1000 patient-days were calculated for each ICU and pooled for ICUs of five German regions for the years 2005 and 2006. A total of 176 ICUs including 284 142 patients and 1 021 579 patient-days reported data concerning 5490 cases of MDR bacteria. The pooled IDs were 4.54, 0.54 and 0.29 cases per 1000 patient-days for MRSA, ESBL-EC/KP and VRE cases and 1.56, 0.32 and 0.13 per 1000 patient-days for MRSA, ESBL-EC/KP and VRE infections, respectively. While there were no significant differences in the incidence densities of MRSA infections between regions, the IDs of VRE and ESBL-EC/KP infections showed significant regional variation. The regions also differed in the proportion of ICUs per region that reported at least one infection with MRSA, ESBL-EC/KP or VRE in 2005–2006 and these differences ranged from 82% to 91% for MRSA, from 34% to 76% for ESBL-EC/KP and from 8% to 42% for VRE. This new surveillance module enables ICUs to monitor the occurrence of MDR bacteria by comparing local incidence densities with a national reference and shows significant regional variation of MDR bacteria in Germany.     

Risk factors for colonization with vancomycin-resistant enterococci in a Melbourne hospital.

OBJECTIVE: To determine risk factors for colonization with vancomycin-resistant enterococci (VRE) in a hospital outbreak. DESIGN: Outbreak investigation and case-control study. SETTING: A referral teaching hospital in Melbourne, Australia. PARTICIPANTS: Cases were inpatients colonized (with or without clinical disease) with VRE between July 26 and November 28, 1998; controls were hospitalized patients without VRE. METHODS: Five cases of VRE were identified between July 26 and November 8, 1998, by growth of VRE from various sites. Active case finding by cultures of rectal swabs from patients surveyed in wards was commenced on July 26, after the first isolate of VRE. RESULTS: There were 19 cases and 66 controls. All the VRE identified were vanB, and all were Enterococcus faecium. One molecular type predominated (18/19 cases). In a logistic-regression model, being on the same ward as a VRE case was the highest risk factor (odds ratio [OR], 82; 95% confidence interval [CI95], 5.7-1,176; P=.001). Having more than five antibiotics (OR, 11.9; CI95 1.1-129.6; P<.05), use of metronidazole (OR, 10.9; CI95, 1.7-69.8; P=.01), and being a medical patient (OR, 8.1; CI95, 1.4-47.6; P<.05) also were significant. Intensive care unit admission was associated with decreased risk (OR, 0.1; CI95, 0.01-0.8; P<.05). CONCLUSION: Our findings are consistent with an acute hospital outbreak. Monitoring and control of antibiotic use, particularly metronidazole, may reduce VRE in our hospital. Ongoing surveillance and staff education also are necessary.     

Nosocomial pulmonary infection by antimicrobial-resistant bacteria of patients hospitalized in intensive care units: risk factors and survival

The objectives of this study were to identify the risk factors of nosocomial pulmonary infection (NPI) in intensive care units (ICUs) associated with antimicrobial-resistant bacteria (NPI-ARB) and to compare survival after NPI-ARB with NPI due to antimicrobial-sensitive bacteria (NPI-ASB). We analysed data from a surveillance network monitoring nosocomial infections in 27 mixed ICUs in the south-east of France. NPI surveillance data were recorded for 628 patients with documented NPI. The patients were stratified into 2 groups by type of pneumonia: NPI-ASB (445 patients) vs. NPI-ARB (183 patients). Variables associated with NPI-ARB were identified++ by multivariate logistic regression. Survival was calculated using the Kaplan-Meier method. A medical condition for ICU admission [odds ratio (OR) 1.98, 95% confidence interval (95% CI) 1.35-2.91], transfer from another hospital ward [OR 1.66, 95% CI (1.14-2.42)], a colonized central venous catheter [OR 3.47, 95% CI (1.46-8.21)], a stay of [eight days [OR 1.02, 95% CI (1.01-1. 05)] and mechanical ventilation [OR 2.10, 95% CI (1.31-3.36)] were independent risk factors of NPI-ARB. Median survival was 35 days after NPI-ARB and 32 days after NPI-ASB (P=0.92). Survival after bacterial NPI was not associated with antimicrobial susceptibility.     

耐甲氧西林金黄色葡萄球菌感染的临床和耐药性

目的通过对重症监护病房(ICU)耐甲氧西林金黄色葡萄球菌( MRSA)感染的分析,探讨正确治疗和防治措施,以预防医院MRSA的发生和流行. 方法对我院ICU 2002年7月1日～2003年1月30日近7个月的追踪观察,对100例MRSA引起的医院感染进行回顾性临床和耐药性分析.结果我院ICU病房7个月内共发生金黄色葡萄球菌感染 104例,其中MRSA感染 100例,占金黄色葡萄球菌感染的95.5%,均全部使用过广谱抗生素,使用≥2种抗生素占43%(OR值1.46,95%CI 1.44 ～3.07),接受＞3种侵入性操作占58%(OR值4.70,95%CI 2.17 ～ 10.19);＞3种基础疾病占51%(OR值2.78,95%CI 1.30～ 5.92). 结论重症监护病房中MRSA的感染率极高,必须引起重视,控制MRSA的感染应积极进行病原学监测、及时发现病例、隔离和治疗患者、合理使用广谱抗生素、严格消毒隔离措施、认真洗手等.     

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

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

重症监护病房MRSA感染的危险因素

目的了解患者入住重症监护病房(ICU) MRSA感染的危险因素。方法选取2014—2016年某三级综合性医院ICU患者825例,采用病例对照研究,病例组为入住ICU 48 h后MRSA感染者,对照组为入住ICU 48h后无MRSA感染者,进行单因素和多因素logistic分析。结果 825例患者中,64例患者发生了MRSA感染,感染率为7. 76%。MRSA感染以肺部感染居多(占45. 31%),其次为皮肤软组织感染(18. 75%)、手术部位切口感染和血流感染(各占9. 38%)、颅内感染和腹腔感染(各占6. 25%)、胸腔感染(4. 68%)。多因素logistic回归分析结果显示,一个月内接受过手术(OR 95%CI:2. 628～9. 166)、外伤(OR 95%CI:2. 248～9. 280)、气管插管时长 7 d(OR95%CI:1. 651～11. 746)、昏迷(OR 95%CI:1. 813～8. 334)、长期卧床(OR 95%CI:1. 362～10. 127)、再次入住ICU(OR 95%CI:1. 475～7. 915)、肠外营养(OR 95%CI:1. 521～7. 518)、使用两联及以上抗菌药物(OR 95%CI:1. 523～6. 132)、多器官功能衰竭(OR 95%CI:1. 024～3. 948)是ICU患者MRSA感染的独立危险因素(均P 0. 05)。结论预防与控制ICU MRSA的产生与传播,应严格执行接触隔离措施,重点关注气管插管、多器官功能衰竭、昏迷、长期卧床、外伤等高危人群MRSA的防控,在患者达到条件的情况下应尽快转出ICU。     

Community-Associated Methicillin-Resistant Staphylococcus aureus, Iowa, USA

We performed antimicrobial drug susceptibility testing and molecular typing on invasive methicillin-resistant Staphylococcus aureus (MRSA) isolates (n = 1,666) submitted to the University of Iowa Hygienic Laboratory during 1999–2006 as part of a statewide surveillance system. All USA300 and USA400 isolates were resistant to <3 non–β-lactam antimicrobial drug classes. The proportion of MRSA isolates from invasive infections that were either USA300 or USA400 increased significantly from 1999–2005 through 2006 (p<0.0001). During 2006, the incidence of invasive community-associated (CA)–MRSA infections was highest in the summer (p = 0.0004). Age <69 years was associated with an increased risk for invasive CA-MRSA infection (odds ratio [OR] 5.1, 95% confidence interval [CI] 2.06–12.64), and hospital exposure was associated with decreased risk (OR 0.07, 95% CI 0.01–0.51).     

Fluoroquinolones and risk for methicillin-resistant Staphylococcus aureus, Canada

Receipt of fluoroquinolones was the predominant risk factor for Clostridium difficile-associated disease (CDAD) during an epidemic in Quebec, Canada. To determine the role of antimicrobial drugs in facilitating healthcare-associated methicillin-resistant Staphylococcus aureus (MRSA) colonization and infection and to compare this role with their effects on methicillin-susceptible S. aureus infection and CDAD, we conducted a retrospective cohort study of patients in a Quebec hospital. For 7371 episodes of care, data were collected on risk factors, including receipt of antimicrobial drugs. Crude and adjusted hazard ratios (AHR) were calculated by Cox regression. Of 150 episodes of MRSA colonization and 23 of MRSA infection, fluoroquinolones were the only antimicrobials that increased risk for colonization (AHR 2.57, 95% confidence interval [CI] 1.84-3.60) and infection (AHR 2.49, 95% CI 1.02-6.07). Effect of antimicrobial drugs on MRSA colonization and infection was similar to effect on CDAD and should be considered when selecting antimicrobial drugs to treat common infections.     

Resistant microorganisms in patients transferred from foreign hospitals

OBJECTIVE: To determine the prevalence of carriers of methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE) and gentamicin-resistant Gram-negative bacilli (GGNB) in patients repatriated from foreign hospitals to The Netherlands. DESIGN: Determination of prevalence. METHOD: In the period May 1998-August 2001, 1167 patients were repatriated. Swab specimens, demographic data and clinical data were obtained during the transfer. RESULTS: The prevalence of carriers of resistant microorganisms was 18.2%. MRSA was carried by 2.7% of the total repatriated group and by 4.7% of patients transferred to a Dutch hospital. Risk factors were antimicrobial treatment (odds ratio (OR): 3.4; 95% CI: 1.2-9.7), length of stay in a foreign hospital > or = 14 days (OR: 5.4; 95% CI: 2.3-12) and artificial ventilation (OR: 8.5; 95% CI: 1.8-41). VRE and GGNB were isolated from 2.7% and 14.1% of patients, respectively. Transfer from Asia or southern, south-eastern and eastern Europe were risk factors for carrying GGNB. CONCLUSION: Carriership of resistant microorganisms was high among repatriated patients. The highest risk of GGNB was more closely associated with the country from which the patient was transferred than the antimicrobial treatment received in the foreign hospital.     

Occurrence of co-colonization or co-infection with vancomycin-resistant enterococci and methicillin-resistant Staphylococcus aureus in a medical intensive care unit.

OBJECTIVE: To determine the occurrence of co-colonization or co-infection with VRE and MRSA among medical patients requiring intensive care. DESIGN: Prospective, single-center, observational study. SETTING: A 19-bed medical ICU in an urban teaching hospital. PATIENTS: Adult patients requiring at least 48 hours of intensive care and having at least one culture performed for microbiologic evaluation. RESULTS: Eight hundred seventy-eight consecutive patients were evaluated. Of these patients, 402 (45.8%) did not have microbiologic evidence of colonization or infection with either VRE or MRSA, 355 (40.4%) were colonized or infected with VRE, 38 (4.3%) were colonized or infected with MRSA, and 83 (9.5%) had co-colonization or co-infection with VRE and MRSA. Multiple logistic regression analysis demonstrated that increasing age, hospitalization during the preceding 6 months, and admission to a long-term-care facility were independently associated with colonization or infection due to VRE and co-colonization or co-infection with VRE and MRSA. The distributions of positive culture sites for VRE (stool, 86.7%; blood, 6.5%; urine, 4.8%; soft tissue or wound, 2.0%) and for MRSA (respiratory secretions, 34.1%; blood, 32.6%; urine, 17.1%; soft tissue or wound, 16.2%) were statistically different (P < .001). CONCLUSIONS: Co-colonization or co-infection with VRE and MRSA is common among medical patients requiring intensive care. The recent emergence of vancomycin-resistant Staphylococcus aureus and the presence of a patient population co-colonized or co-infected with VRE and MRSA support the need for aggressive infection control measures in the ICU.     

Emergence of methicillin-resistant Staphylococcus aureus of animal origin in humans

In 2003 in the Netherlands, a new methicillin-resistant Staphylococcus aureus (MRSA) strain emerged that could not be typed with Sma1 pulsed-field gel electrophoresis (NT-MRSA). The association of NT-MRSA in humans with a reservoir in animals was investigated. The frequency of NT-MRSA increased from 0% in 2002 to >21% after intensified surveillance was implemented in July 2006. Geographically, NT-MRSA clustered with pig farming. A case-control study showed that carriers of NT-MRSA were more often pig or cattle farmers (pig farmers odds ratio [OR] 12.2, 95% confidence interval [CI] 3.1-48.6; cattle farmers OR 19.7, 95% CI 2.3-169.5). Molecular typing showed that the NT-MRSA strains belonged to a new clonal complex, ST 398. This study shows that MRSA from an animal reservoir has recently entered the human population and is now responsible for >20% of all MRSA in the Netherlands.     

The epidemiology of vancomycin-resistant Enterococcus colonization in a medical intensive care unit.

OBJECTIVE: To determine the epidemiology of colonization with vancomycin-resistant Enterococcus (VRE) among intensive care unit (ICU) patients. DESIGN: Ten-month prospective cohort study. SETTING: A 19-bed medical ICU of a 1,440-bed teaching hospital. METHODS: Patients admitted to the ICU had rectal swab cultures for VRE on admission and weekly thereafter. VRE-positive patients were cared for using contact precautions. Clinical data, including microbiology reports, were collected prospectively during the ICU stay. RESULTS: Of 519 patients who had admission stool cultures, 127 (25%) had cultures that were positive for VRE. Risk factors for VRE colonization identified by multiple logistic regression analysis were hospital stay greater than 3 days prior to ICU admission (adjusted odds ratio [AOR], 3.6; 95% confidence interval [CI95], 2.3 to 5.7), chronic dialysis (AOR, 2.4; CI95, 1.2 to 4.5), and having been admitted to the study hospital one to two times (AOR, 2.3; CI95, 1.4 to 3.8) or more than two times (AOR, 6.5; CI95, 3.7 to 11.6) within the past 12 months. Of the 352 VRE-negative patients who had one or more follow-up cultures, 74 (21%) became VRE positive during their ICU stay (27 cases per 1,000 patient-ICU days). CONCLUSION: The prevalence of VRE culture positivity on ICU admission was high and a sizable fraction of ICU patients became VRE positive during their ICU stay despite contact precautions for VRE-positive patients. This was likely due in large part to prior VRE exposures in the rest of the hospital where these control measures were not being used.     

Chloramphenicol resistance in vancomycin-resistant enterococcal bacteremia: impact of prior fluoroquinolone use?

OBJECTIVE: The prevalence of vancomycin-resistant enterococci (VRE) has increased markedly during the past decade. Few data exist regarding the epidemiology of resistance of VRE to chloramphenicol, one of the few therapeutic options. DESIGN: Survey and case-control study. SETTING: A 725-bed, tertiary-care academic medical center and a 344-bed urban community hospital. PATIENTS: Hospitalized patients with blood cultures demonstrating VRE. METHODS: We examined the trends in the prevalence of chloramphenicol resistance in VRE blood isolates at our institution from 1991 through 2002 and conducted a case-control study to identify risk factors for chloramphenicol resistance among these isolates. RESULTS: From 1991 through 2002, the annual prevalence of chloramphenicol-resistant VRE increased from 0% to 12% (P < .001, chi-square test for trend). Twenty-two case-patients with chloramphenicol-resistant VRE bloodstream isolates were compared with 79 randomly selected control-patients with chloramphenicol-susceptible VRE. Independent risk factors for chloramphenicol-resistant VRE were prior chloramphenicol use (odds ratio [OR], 10.9; 95% confidence interval [CI95], 1.72-68.91; P = .01) and prior fluoroquinolone use (OR, 4.74; CI95, 1.15-19.42; P = .03). Chloramphenicol-resistant VRE isolates were more likely to be susceptible to beta-lactams and resistant to tetracycline than were chloramphenicol-susceptible VRE isolates. CONCLUSIONS: Significant increases in the prevalence of chloramphenicol-resistant VRE may limit the future utility of chloramphenicol in the treatment of VRE infections, and close monitoring of susceptibility trends should continue. The association between fluoroquinolone use and chloramphenicol-resistant VRE, reflecting possible co-selection of resistance, suggests that recent dramatic increases in fluoroquinolone use may have broader implications than previously recognized.     

Factors associated with acquisition of vancomycin-resistant enterococci (VRE) in roommate contacts of patients colonized or infected with VRE in a tertiary care hospital.

OBJECTIVE: Most nosocomial acquistion of vancomycin-resistant enterococci (VRE) is due to cross-transmission. We sought to identify risk factors for acquisition of VRE by roommates of patients colonized or infected with VRE. DESIGN: Retrospective cohort study. SETTING: A 472-bed tertiary care teaching hospital. METHODS: All patients who shared a room with a patient colonized or infected with VRE at our hospital between January 1, 1999 and December 31, 2006 were identified. These roommates of VRE-positive patients were screened by rectal swab culture on days 2, 5, and 7 after the last exposure to the index patient. Chart reviews were performed to identify risk factors for VRE colonization in these roommates. RESULTS: Eighty-eight roommates of patients colonized or infected with VRE were identified. Of the 38 roommates with complete follow-up, 8 (21%) became colonized with VRE. These 8 roommates were older (median, 87.5 vs 62.5 years of age; P = .001), had longer duration of room exposure (median, 8.5 vs 4 days; P = .002), and were more likely to have a urinary catheter (odds ratio [OR], 16 [95% confidence interval {CI}, 1.7-152]; P = .005), an elevated serum creatinine level (OR, 17 [95% CI, 1.4-196]; P = .02), low serum albumin level (OR, 9.9 [95% CI, 1.3-113]; P = .01), and recent third-generation cephalosporin use (OR, 8.3 [95% CI, 1.5-47]; P = .02). CONCLUSION: Roommates of patients identified as colonized or infected with VRE are at substantial risk of becoming colonized, with the degree of risk increasing in older and more frail patients. VRE control programs should pay particular attention to such patients.     

两种金黄色葡萄球菌产肠毒素差异的Meta分析

[目的]分析耐甲氧西林金黄色葡萄球菌（ methicillin-resistant Staphylococcus aureus, MRSA ）和甲氧西林敏感金黄色葡萄球菌（ methieillin sensitive Staphylococcus aureus, MSSA ）之间产生肠毒素的差异,为评价MRSA、MSSA与金黄色葡萄球菌食物中毒之间的关系提供参考依据。[方法]采用Meta分析方法对国内外1990-2008年发表的有关MRSA和MSSA产毒株率比较的文献进行汇总、归纳和统计分析。[结果]共检索到7篇文献,合并总RR值为2．18,95％可信区间为1．58～2．99。MRSA中的产毒株率是MSSA的2．18倍。[结论]MRSA产生肠毒素的概率远大于MSSA。     

Methicillin-Resistant and -Susceptible Staphylococcus aureus Infections in Dogs

Methicillin-resistant Staphylococcus aureus (MRSA) has become a pathogen of animals. To compare types of infections, clinical outcomes, and risk factors associated with MRSA in dogs with those associated with methicillin-susceptible Staphylococcus aureus (MSSA) infections, we conducted a case–control study at 3 veterinary referral hospitals in the United States and Canada during 2001–2007. Risk factors analyzed were signalment, medical and surgical history, and infection site. Among 40 dogs with MRSA and 80 with MSSA infections, highest prevalence of both infections was found in skin and ears. Although most (92.3%) dogs with MRSA infections were discharged from the hospital, we found that significant risk factors for MRSA infection were receipt of antimicrobial drugs (odds ratio [OR] 3.84, p = 0.02), β-lactams (OR 3.58, p = 0.04), or fluoroquinolones (OR 5.34, p = 0.01), and intravenous catheterization (OR 3.72, p = 0.02). Prudent use of antimicrobial drugs in veterinary hospitals is advised.     

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

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