Risk factors for methicillin-resistance among patients with Staphylococcus aureus bacteremia at the time of hospital admission

Antibiotic Stewardship Related to Delayed Diagnosis and Poor Prognosis of Critically Ill Patients with Vancomycin-Resistant Enterococcal Bacteremia: A Retrospective Cohort Study

Purpose

Patients with septicemia caused by vancomycin-resistant Enterococcus (VRE) bacteremia have higher mortality rates than patients infected by VSE. Vancomycin or teicoplanin is selected as the antibiotic stewardship intervention to cover methicillin-resistant Staphylococcus aureus infections before blood culture reveals VRE bacteremia in critically ill patients with Gram-positive cocci (GPC) bacteremia; this may require linezolid or daptomycin treatment instead. We thus evaluated antibiotic stewardship practices, such as appropriate timing of antibiotic use in GPC bacteremia, and clinical outcomes of critically ill patients with VRE infection.

Patients and Methods

This retrospective study enrolled 191 critically ill patients with enterococcal bacteremia at the Taipei Tzu Chi Hospital during January 1, 2019–December 31, 2020. Demographic and clinical characteristics, as well as disease outcomes and appropriate antibiotic use after GPC bacteremia diagnosis, were compared between the VRE and VSE groups.

Results

Of 191 patients, 55 had VRE bacteremia (case group) and 136 had VSE bacteremia (control group). The rate of antibiotic change after initial antibiotic use for GPC bacteremia was higher in the VRE bacteremia group (100% vs 10.3%; p<0.001). The time to appropriate antibiotic administration after GPC bacteremia diagnosis was longer in the VRE bacteremia group (3.3±2.1 vs 1.5±1.8 days; p<0.001). Patients with VRE bacteremia had higher 28-day mortality rates (relative risk, 1.997; 95% confidence interval [CI], 1.041–3.83). Multivariate Cox regression analysis showed that delayed appropriate antibiotic administration of >3 days after GPC bacteremia diagnosis increased the risks of 28-day all-cause mortality (adjusted hazard ratio, 2.045; 95% CI, 1.089–3.84; p=0.026) in patients with VRE infection.

Conclusion

Patients with VRE bacteremia with delayed appropriate antibiotic administration of >3 days after GPC bacteremia diagnosis had increased 28-day mortality risks. New strategies for early VRE detection in GPC bacteremia may shorten the time to administer appropriate antibiotics and lower mortality rates.

Community-Acquired Infection With Healthcare-Associated Methicillin-Resistant Staphylococcus aureus: The Role of Home Nursing Care

Objective.

To better understand the role of indirect transmission in community-acquired infection with methicillin-resistant Staphylococcus aureus (MRSA).

Design.

Prospective case-control study.

Setting.

A French teaching hospital.

Patients.

A total of 198 case patients and 198 control patients with MRSA or methicillin-susceptible S. aureus infection diagnosed between April 2002 and July 2003.

Results.

Multivariate analysis showed a highly significant independent link between MRSA infection at admission and prior receipt of home nursing care (odds ratio [OR], 3.7; P<.001). Other independent risk factors were prior hospitalization (OR, 3.8; P<.001), transfer from another institution (OR, 2.3; P = .008), and age older than 65 years (OR, 1.6; P = .04). Prior home nursing care showed a frequency dose-response relationship. Eleven MRSA-infected patients had had home nursing procedures but no hospital stay in the previous 3 years. These patients' MRSA strains were related to the prevalent MRSA clone currently spreading in French hospitals.

Conclusion.

Home nursing care appears to be an independent risk factor for MRSA acquisition in the community. The reservoir probably consists of MRSA carriers discharged from the hospital. Community nurses seem to be a potential vector.

Nursing Home-Acquired Bloodstream Infection

Objectives:

This article reviews published studies of nursing home-acquired BSI in North America to determine whether there have been changes in the epidemiology of this infection in the past 20 years and to define indications for blood cultures in the nursing home setting.

Methods:

A Medline search was conducted for the period from 1980 to August 2003.

Results:

Seven studies of nursing home-acquired BSI were identified. The incidence of nursing home-acquired BSI was low (0.3 episode per 1,000 resident care-days). Sources of BSI changed little during the past two decades, with urinary tract infection representing approximately 50% of the episodes. The bacteriology also did not change substantially during the past 20 years; gram-negative bacilli were isolated in approximately 50% of the episodes and Escherichia coli was the most commonly isolated organism. In the most recent study, covering the period 1997-2000, resistance to fluoroquinolones and broad-spectrum penicillins and cephalosporins was uncommon among gram-negative blood isolates; MRSA was the most common resistant organism causing nursing home-acquired BSI. Case-fatality rates changed little during the past 20 years; urinary tract infection was associated with the lowest mortality and pneumonia had the highest case-fatality rate.

Conclusion:

There has been little change in the epidemiology of nursing home-acquired BSI in the past 20 years. Given the low incidence of BSI and the low overall yield of positive results of blood cultures (probably ≤ 6%), there is currently no support for the routine use of blood cultures in the nursing home setting.

Staphylococcus aureus Bacteremia in Older Adults: Predictors of 7-Day Mortality and Infection With a Methicillin-Resistant Strain

Objectives.

To determine the predictors of 7-day mortality in older adult patients with Staphylococcus aureus bacteremia after controlling for comorbidity using the Charlson weighted index of comorbidity (WIC) and to identify the risk factors associated with bacteremia due to methicillin-resistant S. aureus (MRSA).

Design.

Retrospective cohort study from January 2003 until December 2004.

Setting.

Two tertiary care, university-affiliated hospitals.

Methods.

One hundred thirty-five hospitalized patients with S. aureus bacteremia were included in the study. All patients who were 60 years or older and had 1 or more blood cultures positive for S. aureus were included in the study. The primary outcome was death 7 days after the onset of S. aureus bacteremia.

Results.

Twenty-one patients (15.6%) died within 7 days after the onset of S. aureus bacteremia. Seventy-four patients (56.1%) had MRSA bacteremia. Multivariate analysis identified 3 independent determinants of 7-day mortality: Charlson WIC score greater than 5 (odds ratio [OR], 3.6 [95% confidence interval {CI}, 1.1-11.2]; P = .03), previous hospitalization in the past 3 months (OR, 5.0 [95% CI, 1.1-25.1]; P = .04), and altered mental status at the onset of S. aureus bacteremia (OR, 13.6 [95% CI, 2.9-64.6]; P = .001). Multivariate analysis identified .previous hospitalization in the past 3 months (OR, 2.6 [95% CI, 1.1-5.9]; P = .02), residence in a long-term care facility (OR, 4.5 [95% CI, 1.7-12.3]; P = .003), and altered mental status at the onset of S. aureus bacteremia (OR, 2.5 [95% CI, 1.5-5.6]; P = .02) to be independently associated with the presence of MRSA.

Conclusions.

The Charlson WIC is significantly associated with increased mortality of S. aureus bacteremia in older adults. Previous hospitalization in the past 3 months, residence in a long-term care facility, and altered mental status should be used as a guidance for empirical vancomycin therapy and application of infection control measures in older adults with suspected S. aureus bacteremia.

Prior inpatient admission increases the risk of post-operative infection in hepatobiliary and pancreatic surgery

BACKGROUND

Hepatobiliary and pancreatic (HPB) operations have a high incidence of post-operative nosocomial infections. The aim of the present study was to determine whether hospitalization up to 1 year before HPB surgery is associated with an increased risk of post-operative infection, surgical-site infection (SSI) and infection resistant to surgical chemoprophylaxis.

METHODS

A retrospective cohort study of patients undergoing HPB surgeries between January 2008 and June 2013 was conducted. A multivariable logistic regression model was used for controlling for potential confounders to determine the association between pre-operative admission and post-operative infection.

RESULTS

Of the 1384 patients who met eligibility criteria, 127 (9.18%) experienced a post-operative infection. Pre-operative hospitalization was independently associated with an increased risk of a post-operative infection [adjusted odds ratio (aOR): 1.61, 95% confidence interval [CI]: 1.06-2.46] and SSI (aOR: 1.79, 95% CI: 1.07-2.97). Pre-operative hospitalization was also associated with an increased risk of post-operative infections resistant to standard pre-operative antibiotics (OR: 2.64, 95% CI: 1.06-6.59) and an increased risk of resistant SSIs (OR: 3.99, 95% CI: 1.25-12.73).

DISCUSSION

Pre-operative hospitalization is associated with an increased incidence of post-operative infections, often with organisms that are resistant to surgical chemoprophylaxis. Patients hospitalized up to 1 year before HPB surgery may benefit from extended spectrum chemoprophylaxis.

Optimization of pre-emptive isolations in a polyvalent ICU through implementation of an intervention strategy

BACKGROUND

Pre-emptive isolation refers to the application of contact precaution measures in patients with strongly suspected colonization by multiresistant bacteria.

OBJECTIVE

To assess the impact of an intervention program involving the implementation of a consensus-based protocol of pre-emptive isolation (CPPI) on admission to a polyvalent ICU of a general hospital.

METHODS

A comparative analysis of 2 patient cohorts was made: a historical cohort including patients in which pre-emptive isolation was established according to physician criterion prior to starting CPPI (from January 2010 to February 2011), and a prospective cohort including patients in which CPPI was implemented (from March to November 2011). CPPI included the identification and diffusion of pre-emptive isolation criteria, the definition of sampling methodology, the evaluation of results, and the development of criteria for discontinuation of pre-emptive isolation. Pre-emptive isolation was indicated by the medical staff, and follow-up was conducted by the nursing staff. Pre-emptive isolation was defined as "adequate" when at least one multiresistant bacteria was identified in any of the samples. Comparison of data between the 2 periods was made with the chi-square test for categorical variables and the Student t-test for quantitative variables. Statistical significance was set at P<.05.

RESULTS

Among the 1,740 patients admitted to the ICU (1,055 during the first period and 685 during the second period), pre-emptive isolation was indicated in 199 (11.4%); 111 (10.5%) of these subjects corresponded to the historical cohort (control group) and 88 (12.8%) to the posterior phase after the implementation of CPPI (intervention group). No differences were found in age, APACHE II score or patient characteristics between the 2 periods. The implementation of CPPI was related to decreases in non-indicated pre-emptive isolations (29.7 vs. 6.8%, P<.001), time of requesting surveillance cultures (1.56 vs. 0.37 days, P<.001), and days of duration of treatment (4.77 vs. 3.58 days, P<.001). In 44 patients (22.1%) in which pre-emptive isolation was indicated, more than one multiresistant bacteria was identified, with an "adequate pre-emptive isolation rate" of 19.8% in the first period and 25.0% in the second period (P<.382).

CONCLUSIONS

The implementation of CPPI resulted in a significant decrease in pre-emptive isolations which were not indicated correctly, a decrease in the time elapsed between isolation and collection of samples, and a decrease in the duration of isolation measures in cases in which isolation was unnecessary, without increasing the rate of "adequate pre-emptive isolation".

Nasal MRSA screening for surgical patients: predictive value for postoperative infections caused by MRSA

PURPOSE

Postoperative methicillin-resistant Staphylococcus aureus (MRSA) infections are occasionally fatal. We hypothesized that nasal MRSA screening might predict the risk of postoperative MRSA infections. The aim of the current study was to elucidate the relationship between the positivity of nasal MRSA screening and postoperative MRSA infections.

METHODS

Six hundred and fourteen surgical patients who were admitted to the intensive care unit and underwent nasal MRSA screening between April 2006 and March 2011 were divided into MRSA-positive and -negative groups. The incidence of postoperative MRSA infections in the MRSA-positive and MRSA-negative groups were compared, and various risk factors for MRSA infections were evaluated.

RESULTS

The incidence of postoperative MRSA infections, such as pneumonia and enteritis, in the MRSA-positive group was significantly higher than that in the MRSA-negative group (41.9 vs. 3.1 %). The significant independent risk factors for postoperative MRSA infections were a positive MRSA screening, an operation lasting more than 300 min and an emergency operation. A positive MRSA screening was the most statistically significant risk factor for postoperative MRSA pneumonia and enteritis, but was not a risk factor for MRSA surgical site infections.

CONCLUSION

Nasal MRSA screening can help to identify patients who have an increased risk of developing postoperative MRSA infections, and would enable physicians to take a prompt action if these complications occur.

Comparison of the bacterial isolates and antibiotic resistance patterns of elderly nursing home and general community patients

BACKGROUND

Nursing home-acquired infections may differ from general community-acquired infections in bacteriology and antibiotic resistance. However, there are currently limited data on this topic in the Australian setting.

AIMS

To compare bacterial isolates and antibiotic resistance patterns, from pathology specimens of nursing home and community patients, and to comment on the suitability of empiric antibiotic guidelines for nursing home-acquired infection.

METHODS

This was a retrospective cohort study of patients, aged ≥ 65 years, who resided in either nursing homes or the general community. Patients with a hospital admission in the previous 28 days were excluded. Positive specimen cultures, collected between July 2003 and June 2008 in the Emergency Department and Outpatient Clinics of the Austin Hospital (Melbourne), were examined. The main outcome measures were the bacterial isolates, and their antibiotic resistance patterns, of patients from nursing homes and the general community.

RESULTS

Specimens of blood (638), sputum (425), urine (4044) and wound cultures (785) were examined. The bacteriology of blood culture isolates did not differ between the two groups (P= 0.3). However, the bacteriology of sputum, urine and wound cultures differed significantly between the groups (P= 0.025, P < 0.001, P= 0.004 respectively). There were also higher proportions of antibiotic resistance among some bacteria in nursing home patients, especially methicillin resistance among Staphylococcus aureus isolates across all specimen types, and resistance to several empiric antibiotics among Enterobacteriaceae isolates in urine cultures.

CONCLUSION

Empiric antibiotic guidelines appear adequate to treat nursing home-acquired septicaemia and pneumonia. However, guidelines for urinary tract infections and wound infections may need to be refined.

Risk factors and outcomes of methicillin-resistant Staphylococcus aureus bacteraemia in critically ill patients: a case control study

Methicillin-resistant Staphylococcus aureus (MRSA) infection is an increasing threat to critically ill patients in many intensive care units. MRSA bacteraemia is an extreme form of MRSA infection and is a significant cause of morbidity and mortality. This case control study aimed to assess the risk factors and outcomes of MRSA bacteraemia compared to methicillin-susceptible Staphylococcus aureus (MSSA) bacteraemia. A total of 21 MRSA bacteraemia and 60 randomly selected MSSA bacteraemia episodes, admitted to the intensive care unit at Royal Perth Hospital between 1997 and 2007, were considered. There was a suggestion that hospitalisation within the preceding six months (P = 0.087) and residence in a long-term care facility (P = 0.065) were associated with a higher risk of MRSA bacteraemia. MRSA bacteraemia was more often treated with antibiotics to which the pathogen was not susceptible in vitro (38.1% vs 0%, P = 0.001), resulting in a longer duration of fever (median 7.0 vs 2.0 days, P= 0.009) and bacteraemia (mean 3.2 vs 0.6 days, P = 0.005) and a higher incidence of metastatic seeding of infection (52.4% vs 21.7%, P = 0.012) as compared to MSSA bacteraemia. While in-hospital mortality between MRSA and MSSA was similarly high (47.6% vs 38.3% for MRSA and MSSA respectively, P = 0.607), a significant proportion of the patients who had MRSA bacteraemia died within five years of hospital discharge (36.4%, hazard ratio 26.0, 95% confidence interval 1.90 to 356.7, P = 0.015). Infections contributed to 75% of the deaths after hospital discharge in patients who had an episode of MRSA bacteraemia. MRSA bacteraemia carries a much worse long-term prognosis than MSSA bacteraemia and that could be explained by recurrent MRSA infections and residual confounding.

The incidence of and risk factors for MRSA bacteraemia in an HIV-infected cohort in the HAART era

OBJECTIVES

To define the incidence and risk factors for methicillin resistant Staphylococcus aureus (MRSA) bacteraemia in an HIV-infected population.

METHODS

From January 1, 2000 to December 31, 2004, we conducted a retrospective cohort study. We identified all cases of Staphylococcus aureus bacteraemia (SAB), including MRSA, among patients enrolled in the Johns Hopkins Hospital out-patient HIV clinic. A conditional logistic regression model was used to identify risk factors for MRSA bacteraemia compared with methicillin-sensitive SAB and no bacteraemia in unmatched (1:1) and matched (1:4) nested case-control analyses, respectively.

RESULTS

Of 4607 patients followed for a total of 11 020 person-years (PY) of follow-up, 216 episodes of SAB occurred (incidence: 19.6 cases per 1000 PY), including 94 cases (43.5%) which were methicillin-resistant. The incidence of MRSA bacteraemia increased from 5.3 per 1000 PY in 2000-2001 to 11.9 per 1000 PY in 2003-2004 (P=0.001). Multivariate analysis demonstrated that independent predictors of MRSA bacteraemia (vs. no bacteraemia) were injection drug use (IDU), end-stage renal disease (ESRD) and CD4 count <200 cells/microL.

CONCLUSIONS

MRSA bacteraemia was an increasingly common diagnosis in our HIV-infected cohort, especially in patients with history of IDU, low CD4 cell count and ESRD.

Control of endemic methicillin-resistant Staphylococcus aureus--recent advances and future challenges

Although the exact burden of disease caused by methicillin-resistant Staphylococcus aureus (MRSA) remains largely unknown, most experts agree that MRSA infections are an important clinical and public health problem. Thousands of reports have been published during the last four decades concerning epidemiological and microbiological aspects of MRSA, but uncertainty remains about the best approach to prevent and control this worldwide plague, especially endemic MRSA. Epidemiological methods, e.g., risk scores for targeted screening upon admission, rapid molecular tests and pre-emptive isolation of high-risk patients, new decontamination regimens and restriction of certain antibiotic classes, are all promising approaches that may decrease MRSA cross-transmission; however, further evidence is needed before these strategies can be implemented on a wide scale. Control of community MRSA is an additional challenge for the future, requiring improved surveillance and contact tracing, as well as education and treatment of both infected cases and colonised contacts. This review summarises recent advances and studies that address these issues. Overall, it seems that there is no level of MRSA prevalence for which active control measures are no longer warranted.

Bacteremia and sepsis in older adults

Bacteremia and sepsis are common complications of infection in older patients. Comorbidities, institutionalization, instrumentation, and immunosenescence place older persons at high risk for bacteremia and sepsis, and clinicians must have a heightened suspicion for these infectious disorders in older patients because nonspecific clinical manifestations of infection are common in this vulnerable population. Although increasing age is associated with a high risk of death due to bacteremia and sepsis, recent evidence suggests that many older patients respond well to treatments of proven efficacy. This article discusses the epidemiology, pathophysiology, diagnosis, and prognosis of bacteremia and sepsis in older patients and provides evidence-based recommendations regarding the treatment of these infectious disorders in older persons.

Analysis of methicillin resistance among Staphylococcus aureus blood isolates in an emergency department

The increasing prevalence of methicillin-resistant Staphylococcus aureus (MRSA) has become of great concern in both hospital and community settings. To evaluate the prevalence and risk factors for methicillin resistance among Staphylococcus aureus, blood isolates in our Emergency Department (ED) were collected. All patients with S. aureus bacteremia (SAB) who presented to the ED from January 2000 to August 2005 were included, and a retrospective study was performed. A total of 231 patients with SAB were enrolled (median age, 59 yr; M:F, 125:106). Among these patients, methicillin-resistant strains accounted for 27.3% (63 patients). Catheter-related infection was the most frequent primary site of SAB (39.0%), followed by skin and soft tissue infection (16.5%). In multivariate analysis, recent surgery (OR, 3.41; 95% CI, 1.48-7.85), recent hospitalization (2.17; 1.06-4.62), and older age (> or =61 yr) (2.39; 1.25-4.57) were independently associated with the acquisition of methicillin-resistant strains. When antimicrobial therapy is considered for the treatment of a patient with suspected SAB, clinicians should consider obtaining cultures and modifying empirical therapy to provide MRSA coverage for patients with risk factors: older age, recent hospitalization, and recent surgery.

Clinical and molecular epidemiology of nursing home-associated Staphylococcus aureus bacteremia

BACKGROUND AND OBJECTIVES

Although nursing home residents who have Staphylococcus aureus bacteremia (SAB) have been included in large studies of this infection, there are no published descriptions of SAB solely in nursing home residents. The objectives were to describe the clinical and molecular epidemiology of SAB in nursing home residents admitted to one hospital.

METHODS

This was a retrospective review of hospital medical records of nursing home residents from 22 separate facilities who had SAB and were admitted to a specialty unit at one hospital from 1997 to 2003.

RESULTS

For the seven-year study period, 39 episodes of SAB were identified; 15 were due to methicillin-susceptible S. aureus (MSSA) and 24 were due to methicillin-resistant S. aureus (MRSA). The incidence of SAB among all residents admitted to the specialty unit increased by more than eightfold primarily because of an increased incidence of bacteremia due to MRSA. The most common identified source was the urinary tract (18% of all episodes) but for 17 (44%) episodes, no focus was identified. Hospital mortality was 28% with all deaths occurring within 15 days of admission. Analysis of the MRSA strains by pulsed-field gel electrophoresis revealed that two pulsed-field types predominated when compared with the CDC national database: USA100- (N = 13) and USA 800-like strains (N = 7).

CONCLUSIONS

In the study population there was a substantial increase in incidence of SAB over a 7-year period due almost exclusively to an increased occurrence of MRSA. Hospital strains of MRSA predominated, as one would expect. Mortality was high but complications were low among survivors. These findings have important implications for choosing empiric antibiotic therapy in nursing home residents who have suspected S. aureus infection.

Methicillin-resistant Staphylococcus aureus on orthopaedic wards: incidence, spread, mortality, cost and control

We examined the rates of infection and colonisation by methicillin-resistant Staphylococcus aureus (MRSA) between January 2003 and May 2004 in order to assess the impact of the introduction of an MRSA policy in October 2003, which required all admissions to be screened. Emergency admissions were treated prophylactically and elective beds ring-fenced. A total of 5,594 admissions were cross-referenced with 22,810 microbiology results. The morbidity, mortality and cost of managing MRSA-carrying patients, with a proximal fracture of the femur were compared, in relation to age, gender, American Society of Anaesthesiologists grade and residential status, with a group of matched controls who were MRSA-negative. In 2004, we screened 1795 of 1,796 elective admissions and MRSA was found in 23 (1.3%). We also screened 1,122 of 1,447 trauma admissions and 43 (3.8%) were carrying MRSA. All ten ward transfers were screened and four (40%) were carriers (all p < 0.001). The incidence of MRSA in trauma patients increased by 2.6% per week of inpatient stay (r = 0.97, p < 0.001). MRSA developed in 2.9% of trauma and 0.2% of elective patients during that admission (p < 0.001). The implementation of the MRSA policy reduced the incidence of MRSA infection by 56% in trauma patients (1.57% in 2003 (17 of 1,084) to 0.69% in 2004 (10 of 1,447), p = 0.035). Infection with MRSA in elective patients was reduced by 70% (0.56% in 2003 (7 of 1,257) to 0.17% in 2004 (3 of 1,806), p = 0.06). The cost of preventing one MRSA infection was 3,200 pounds. Although colonisation by MRSA did not affect the mortality rate, infection by MRSA more than doubled it. Patients with proximal fractures of the femur infected with MRSA remained in hospital for 50 extra days, had 19 more days of vancomycin treatment and 26 more days of vacuum-assisted closure therapy than the matched controls. These additional costs equated to 13,972 pounds per patient. From this experience we have been able to describe the epidemiology of MRSA, assess the impact of infection-control measures on MRSA infection rates and determine the morbidity, mortality and economic cost of MRSA carriage on trauma and elective orthopaedic wards.

Community-onset healthcare-associated MRSA bacteraemia in a district general hospital

Methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia is associated with significant mortality and morbidity. This retrospective study involved 76 episodes over four years in a district general hospital in the UK. Twenty-eight of these episodes (36.8%) occurred within 72 h of admission. All of these, however, had risk factors for MRSA acquisition and were classified as healthcare-associated bacteraemias. The mortality rates (all causes) at seven days and three months were 31.5% and 53.4%, respectively. Ten patients died before targeted therapy could be commenced. All patients in the study had multiple comorbidities, and pneumonia was a common diagnosis. Previous antibiotics, increased age, admission on surgical wards/intensive care units, and the presence of central venous cannulae and urinary catheters were risk factors for infection. In 48.7% of episodes, patients were not known to be colonized with MRSA prior to their bacteraemia. Empirical targeted therapy should be given to patients with risk factors for MRSA and staphylococci in blood cultures pending susceptibility results. Increased use of screening may also be required to reduce transmission and increase the likelihood of appropriate empirical antimicrobial therapy. Eradication of MRSA from carriers in the community should be considered to reduce the number of community-onset healthcare-associated bacteraemias.

Evaluating the probability of previously unknown carriage of MRSA at hospital admission

PURPOSE

We determined the prevalence and risk profile of patients with previously unknown carriage of methicillin-resistant Staphylococcus aureus (MRSA) at hospital admission.

SUBJECTS AND METHODS

We conducted a 7-month, prospective case-controlled study in adult inpatients admitted to a university hospital with endemic MRSA. Multivariate conditional logistic regression for data sets matched 1:4 was performed to identify the risk profile of newly identified MRSA carriers.

RESULTS

Overall, 399 of 12072 screened admissions (prevalence, 3.3%) were found colonized (n = 368, 92%) or infected (n = 31, 8%) with MRSA. In 204 cases (prevalence, 1.7%), MRSA carriage was newly identified. Without screening on admission, 49% (196/399) of MRSA carriers would have been missed. We identified nine independent risk factors for newly identified MRSA carriage at admission (adjusted odds ratio): male sex (1.9); age greater than 75 years (2.0); receipt of fluoroquinolones (2.7), cephalosporins (2.1), and carbapenems (3.2) in the last 6 months; previous hospitalization (1.9) or intravenous therapy (1.7) during the last 12 months; urinary catheter at admission (2.0); and intrahospital transfer (2.4). A risk score (range, 0-13) was calculated by adding points assigned to these variables. On the basis of analysis of 1006 patients included in the case-controlled study, the probability of MRSA carriage was 8% (28/342) in patients with a low score (< or =1), 19% (92/482) in patients with an intermediate score (2-4), and 46% (84/182) in patients with a high score (> or =5). The risk score had good discrimination (c-statistic, 0.73) and showed excellent calibration (P = .88).

CONCLUSIONS

On-admission prevalence of previously unknown MRSA carriers was high. Applying the risk score to newly admitted patients with an intermediate or high probability of MRSA carriage could allow a more effective MRSA control strategy.

MRSA bacteraemia in patients on arrival in hospital: a cohort study in Oxfordshire 1997-2003

OBJECTIVE

To describe the incidence and determinants of methicillin resistant and methicillin sensitive Staphylococcus aureus (MRSA and MSSA) bacteraemia in patients presenting to acute hospitals.

DESIGN

Anonymised record linkage study with information from hospital information systems and microbiology databases.

SETTING

One teaching hospital and one district general hospital in Oxfordshire.

PARTICIPANTS

All patients admitted to a teaching hospital 1 April 1997 to 31 March 2003 and to a district general hospital 1 April 1999 to 31 March 2003.

MAIN OUTCOME MEASURES

Detection of MRSA and MSSA from blood cultures taken during the first two days of admission to hospital.

RESULTS

In the teaching hospital, there were 479 patients with MSSA and 116 with MRSA bacteraemia admitted from the community. Among this group, which comprised 24% of all hospital MRSA cases, 31% (36 cases) of patients had been admitted to renal, oncology, or haematology services for intensive day case therapy. The 69% remaining were most commonly patients admitted as medical or surgical emergencies. At least 91% had been in hospital previously; the median time since discharge was 46 days. About half of cases were in patients in whom MRSA had not been isolated before. Similar epidemiology was observed in the district general hospital.

CONCLUSION

Diagnostic algorithms and policies on use of antibiotics need to reflect the fact that a quarter of hospital MRSA cases occur in patients who have previously been in hospital and are subsequently readmitted.

Characteristics of community-acquired and health care-associated Staphylococcus aureus bacteremia in patients treated at the emergency department of a teaching hospital

The changing epidemiology of Staphylococcus aureus bacteremia has been noted worldwide. This enhanced awareness appears to be closely associated with the evolution of health care systems. To further delineate this change and to clarify the prevalence of true community-acquired methicillin-resistant S. aureus (MRSA), reclassification for community-onset bacteremia was proposed. Exposure to health care system, such as nursing home residence, regular outpatient invasive interventions, and prior hospitalization within 1 year, was identified among the community-onset S. aureus bacteremia patients. During the 1-year study period, 102 episodes of S. aureus bacteremia from the emergency department patients of a teaching hospital were prospectively enrolled. Nine of the episodes were hospital-acquired, 56 episodes were associated with health care system exposure, and the remaining 37 episodes were classified as true community-acquired bacteremia. The characteristics of patients, primary site of infection, antimicrobial susceptibilities of S. aureus isolates, adequacy of initial antimicrobial therapy, and percentage of metastatic infections differed significantly between health care-associated and true community-acquired S. aureus bacteremias. Prevalence of MRSA infection in true community-acquired bacteremia was low in contrast to bacteremia with health care-associated exposure (2.7% versus 42.9%, P < 0.01). In conclusion, clinical characteristics and risk of contracting methicillin-resistant S. aureus bacteremia among community patients with and without exposure to health care system are distinct. Precise classification of patients is mandatory for the surveillance of antimicrobial resistance and selection of rationale empirical antibiotics.

Rapidly progressive soft tissue infections

Skin and soft tissue infections are among the most common reasons for people to seek medical advice. They also represent one of the most common indications for antimicrobial therapy and account for approximately 7-10% of hospitalisations in North America. Although non-limb and non-life threatening infections may be treated on an out-patient basis with oral antibiotics, patients with more serious acute skin and soft tissue infections may require admission to hospital for management; this decision is especially true if the infection is rapidly progressive. We provide a concise overview of the differential diagnosis and approach to management of community-acquired rapidly progressive skin and soft tissue infections.

Nontyphoid Salmonella Bacteremia in Patients with Liver Cirrhosis

BACKGROUND

Bacteremia is reported to occur in 4% to 9% of hospitalized patients with liver cirrhosis. Escherichia coli and Klebsiella pneumoniae are the most commonly isolated organisms. Only sporadic cases of nontyphoid Salmonella bacteremia are reported in the literature. In this study, we sought to determine the clinical features and prognosis of patients with liver cirrhosis and bacteremia due to nontyphoid Salmonella.

METHOD

Data were collected by retrospective chart review.

RESULTS

From December 1996 to May 2003, we identified 23 patients (18 males, 5 females) with a median age of 58 years. The Child classification for liver cirrhosis was A in 4, B in 9, and C in 10 patients. Solid organ cancers were present in 14 patients: hepatocellular carcinoma in 13 patients and gastric carcinoma in 1 patient. Hospital death occurred in 11 patients (48%): 7 died of sepsis and 4 of hepatic failure. Using a logistic regression model, the independent risk factors for death in patients with nontyphoid Salmonella bacteremia were young age and an advanced stage of liver cirrhosis.

CONCLUSION

Most nontyphoid Salmonella bacteremia in patients with liver cirrhosis was community-acquired. An advanced stage of liver cirrhosis and hepatocellular carcinoma were common. The prognosis for young patients was unfavorable; this was seemingly due to hepatocellular carcinoma producing more unfavorable results in younger cirrhotic patients.

Necrotizing fasciitis caused by community-associated methicillin-resistant Staphylococcus aureus in Los Angeles

BACKGROUND

Necrotizing fasciitis is a life-threatening infection requiring urgent surgical and medical therapy. Staphylococcus aureus has been a very uncommon cause of necrotizing fasciitis, but we have recently noted an alarming number of these infections caused by community-associated methicillin-resistant S. aureus (MRSA).

METHODS

We reviewed the records of 843 patients whose wound cultures grew MRSA at our center from January 15, 2003, to April 15, 2004. Among this cohort, 14 were identified as patients presenting from the community with clinical and intraoperative findings of necrotizing fasciitis, necrotizing myositis, or both.

RESULTS

The median age of the patients was 46 years (range, 28 to 68), and 71 percent were men. Coexisting conditions or risk factors included current or past injection-drug use (43 percent); previous MRSA infection, diabetes, and chronic hepatitis C (21 percent each); and cancer and human immunodeficiency virus infection or the acquired immunodeficiency syndrome (7 percent each). Four patients (29 percent) had no serious coexisting conditions or risk factors. All patients received combined medical and surgical therapy, and none died, but they had serious complications, including the need for reconstructive surgery and prolonged stay in the intensive care unit. Wound cultures were monomicrobial for MRSA in 86 percent, and 40 percent of patients (4 of 10) for whom blood cultures were obtained had positive results. All MRSA isolates were susceptible in vitro to clindamycin, trimethoprim-sulfamethoxazole, and rifampin. All recovered isolates belonged to the same genotype (multilocus sequence type ST8, pulsed-field type USA300, and staphylococcal cassette chromosome mec type IV [SCCmecIV]) and carried the Panton-Valentine leukocidin (pvl), lukD, and lukE genes, but no other toxin genes were detected.

CONCLUSIONS

Necrotizing fasciitis caused by community-associated MRSA is an emerging clinical entity. In areas in which community-associated MRSA infection is endemic, empirical treatment of suspected necrotizing fasciitis should include antibiotics predictably active against this pathogen.

Methicillin-resistant Staphylococcus aureus and beyond: what's new in the world of the golden staph?

Methicillin-resistant Staphylococcus aureus (MRSA) continues to plague our hospitals. With the appearance of isolates that are resistant to vancomycin, now, more than ever, we must direct our efforts to controlling its development and spread. New antimicrobials have become available for treatment, but may only be a short-term answer. Our efforts towards control must be directed towards infection control measures such as improved hand hygiene with user-friendly products, such as alcohol-based hand disinfectants. Intranasal mupirocin may have a place in prevention of surgical site infection, although this role has not yet been clearly defined. Other areas where MRSA control may be effected include prudent controlled use of antibiotics, including surgical prophylaxis.

Pathogens resistant to antimicrobial agents: epidemiology, molecular mechanisms, and clinical management

Resistance to antimicrobial drugs is increasing at an alarming rate among both gram-positive and gram-negative bacteria. Traditionally, bacteria resistant to multiple antimicrobial agents have been restricted to the nosocomial environment. A disturbing trend has been the recent emergence and spread of resistant pathogens and resistance traits in nursing homes, the community, as well as in hospitals. This article reviews the epidemiology, molecular mechanisms of resistance, and treatment options for pathogens resistant to antimicrobial drugs.

Community-acquired bacteraemia in a rural area: predominant bacterial species and antibiotic resistance

The invasion of the bloodstream represents one of the most important sequelae of infection. This study was conducted over an 18-month period to determine the predominant bacterial agents of a community-acquired bacteraemia seen at health centres in a rural area of Jordan, and their antibiotic susceptibilities. Blood samples were collected and cultured from 215 patients who presented with fever and presumed diagnosis of a bacteraemia. Isolates were identified and tested for antibiotic susceptibility. The variables included the age and sex of the patients, aetiology, sources of the bacteraemia, risk factors, treatment and outcome. One hundred and twenty-six (58.6%) blood cultures were positive. Children less than 14 years old accounted for 34.9% of these, and 38% were from patients that were more than 50 years old. The most frequent aetiologic agents were Staphylococcus aureus, followed by Brucella melitensis and Streptococcus pneumoniae. A wide range of resistance to commonly used antimicrobial agents and multidrug resistance was documented in 44.4% of the isolates. The most frequent sources of the bacteraemia were urinary (15.9%), respiratory (14.3%), no source of the bacteraemia identified (primary bacteraemia) (13.5%), gastrointestinal (12.7%) and soft-tissue infection (7.9%). No identifiable risk factor for infection could be determined in 34% of the patients. The predominant pathogens identified and the relatively high prevalence of antibiotic resistance of the isolates are most probably due to the nature and lifestyle of this rural population and the use of empiric treatment. Characteristics permitting recognition of patients with such strains would aid infection control efforts in the community.

Prevention and control of methicillin-resistant Staphylococcus aureus infections

PURPOSE OF REVIEW

This article reviews many recent publications relevant to the prevention and control of nosocomial methicillin-resistant Staphylococcus aureus (MRSA) infection.

RECENT FINDINGS

Higher risk-adjusted costs and mortality have been found for MRSA infections than for methicillin-susceptible S. aureus infections confirming their epidemiologic importance. Staphylococcal cassette chromosome mec, the genetic basis for MRSA, does not develop in methicillin-susceptible S. aureus exposed to antimicrobials. Instead virtually all patients acquire MRSA via spread. Nevertheless, antibiotic therapy provides a selective advantage for such spread, especially within healthcare settings where antimicrobial therapy is most frequent. Several studies have suggested better control of MRSA through antibiotic control, but far more studies have reported control using surveillance cultures and contact precautions for preventing spread (rather than just using standard precautions). More rapid detection of MRSA (within 6 h) has been reported using polymerase chain reaction, but studies using this method to reduce spread have not yet been published. A structured survey of research methods used regarding MRSA control noted that many studies had methodologic shortcomings (for example, none was a randomized trial), but nevertheless concluded that active detection and isolation work should be used. A Society for Healthcare Epidemiology of America guideline emphasized the same approach noting that scores of studies on multiple continents had reported success with this approach, with best results in several northern-European countries where all facilities used it routinely.

SUMMARY

Improved MRSA control is possible by detecting and isolating colonized patients.

Impact of Methicillin Resistance on Clinical Features and Outcomes of Infective Endocarditis Due to Staphylococcus aureus

BACKGROUND

This study sought to determine the impact of methicillin resistance on clinical features and outcomes in patients with Staphylococcus aureus (SA) infective endocarditis (IE).

METHODS

Retrospective chart review. Univariate and forward stepwise logistic regressions were conducted to determine which factors significantly affected death and systemic embolism.

RESULTS

From October 1995 to April 2002, 57 patients with a definite diagnosis of IE caused by SA were included: 28 cases of methicillin-sensitive SA infection and 29 methicillin-resistant SA (MRSA) infection. Patients with MRSA infection are more likely to have old age, underlying diseases, history of hospitalization within the last 6 months, nosocomial infection, and antibiotic use within the last 3 months. Patients with MRSA infection had clinical presentation of less systemic embolism and more sepsis and had a higher 3-month mortality rate. Methicillin resistance is an independent positive predictor of death and a negative predictor of systemic embolism.

CONCLUSIONS

MRSA became a dominant cause of SA IE. Although it caused a lower incidence of systemic embolism, MRSA infection had a higher mortality rate because of sepsis.

Control of endemic MRSA-what is the evidence? A personal view

Although there is extensive literature on the control of MRSA, when that concerning epidemics is excluded, only a limited amount remains regarding the control of endemic MRSA. Several guidelines have been recently published recommending stringent control measures, which are often suggested based on their success in controlling MRSA outbreaks in hospitals with few MRSA or in containing MRSA cases introduced into a hospital with no MRSA. In these settings, multiple measures are usually introduced with apparently successful results. However, results may not be generalizable to other settings and we do not know the minimum effective measures required for MRSA containment. This paper aims critically to review the literature to determine whether evidence exists for the value of the infection control measures that are widely recommended in the endemic setting. Much of this literature is based on observational studies, with few randomized, controlled trials having been conducted. More well-designed studies are required before many of the principles on which we build infection control programmes can be regarded as evidence based.

Risk factors for acquisition of methicillin-resistant Staphylococcus aureus (MRSA) by trauma patients in the intensive care unit

In a previous study in the intensive care unit (ICU) of the Alfred Hospital, Melbourne, Australia, it was demonstrated that trauma patients were at particular risk of becoming colonized by methicillin-resistant Staphylococcus aureus (MRSA). We examined risk factors for MRSA acquisition in these patients using a cohort study comparing the 31 patients who acquired MRSA with 65 who did not. Data collected included ICU length of stay (LOS), mechanism of trauma, site of injury, type of surgery, trauma severity and antibiotic usage. Odds ratios (OR) were determined and adjusted for LOS. LOS in the ICU was a significant univariate predictor of MRSA acquisition (OR 13.7). When adjusted for LOS, mechanism of trauma (OR 10.4), laparotomy (OR 6.3) and administration of ticarcillin/clavulanic acid (OR 4.5) or glycopeptides (OR 5.9) remained significant. We confirmed our previous finding that LOS was associated with MRSA acquisition. Receipt of antibiotics correlated with reported literature. Novel associations were road trauma as a mechanism and laparotomy.

Rapid molecular diagnosis of lactobacillus bacteremia by terminal restriction fragment length polymorphism analysis of the 16S rRNA gene

OBJECTIVE

Bacteremia due to lactobacilli is uncommon, yet it is increasing in frequency, especially among immunosuppressed patients. In the clinical laboratory, lactobacilli must be subcultured from positive blood cultures before identification by traditional biochemical methods. Delays in diagnosis are significant because the organisms are inherently resistant to vancomycin, a drug frequently prescribed for empiric therapy for gram-positive bacteremia. Recently, we developed a rapid terminal-restriction fragment length polymorphism (T-RFLP) diagnostic assay based on species-specific variations in the bacterial 16S rRNA gene. We sought to apply this technique to the identification of Lactobacillus spp. from three cases of bacteremia.

DESIGN

The results of the T-RFLP analysis are compared with two standard biochemical identification methods.

METHODS

Lactobacillus strains were isolated from positive clinical blood cultures. Initial suspect cultures were subcultured and characterized using an automated substrate hydrolysis system and Lactobacillus carbohydrate fermentation profiles. Further biochemical and molecular analyses were performed from isolates propagated in Lactobacillus MRS broth. DNA was extracted and the 16S rRNA gene sequenced. Two sets of fluorescent labeled primers targeting the 16S rRNA gene were used for polymerase chain reaction (PCR) with chromosomal preparations from reference strains and blood isolates. The PCR products were digested with restriction enzymes and terminal-restriction fragment profile analysis performed.

RESULTS

T-RFLP analysis correctly identified the Lactobacillus species in each case. T-RFLP analysis could be completed within 8 hours of obtaining a positive blood culture as compared to more than the 24 to 48 hours required for traditional culturing and biochemical characterizations.

CONCLUSION

T-RFLP analysis allows for rapid identification of Lactobacillus directly from positive blood cultures and circumvents the requirement for subculture. Reduced diagnostic time has implications for duration of infection, the cost of patient care, length of hospitalization, development of broad-spectrum antibiotic resistance, and mortality due to bacteremia. T-RFLP profiling represents a highly reproducible and predictive source for identification of many organisms associated with bacteremia.

Prediction model to identify patients with Staphylococcus aureus bacteremia at risk for methicillin resistance

OBJECTIVES

To identify institution-specific risk factors for MRSA bacteremia and develop an objective mechanism to estimate the probability of methicillin resistance in a given patient with Staphylococcus aureus bacteremia (SAB).

DESIGN

A cohort study was performed to identify institution-specific risk factors for MRSA. Logistic regression was used to model the likelihood of MRSA. A stepwise approach was employed to derive a parsimonious model. The MRSA prediction tool was developed from the final model.

SETTING

A 279-bed, level 1 trauma center.

PATIENTS

Between January 1, 1999, and June 30, 2001, 494 patients with clinically significant episodes of SAB were identified.

RESULTS

The MRSA rate was 45.5%. Of 18 characteristics included in the logistic regression, the only independent features for MRSA were prior antibiotic exposure (OR, 9.2; CI95, 4.8 to 17.9), hospital onset (OR, 3.0; CI95, 1.9 to 4.9), history of hospitalization (OR, 2.5; CI95, 1.5 to 3.8), and presence of decubitus ulcers (OR, 2.5; CI95, 1.2 to 4.9). The prediction tool was derived from the final model, which was shown to accurately reflect the actual MRSA distribution in the cohort.

CONCLUSION

Through multivariate modeling techniques, we were able to identify the most important determinants of MRSA at our institution and develop a tool to predict the probability of methicillin resistance in a patient with SAB. This knowledge can be used to guide empiric antibiotic selection. In the era of antibiotic resistance, such tools are essential to prevent indiscriminate antibiotic use and preserve the longevity of current antimicrobials.

A consensus statement on empiric therapy for suspected gram-positive infections in surgical patients

BACKGROUND

Multidrug resistance among gram-positive pathogens in tertiary and other care centers is common. A systematic decision pathway to help select empiric antibiotic therapy for suspected gram-positive postsurgical infections is presented.

DATA SOURCES

A Medline search with regard to empiric antibiotic therapy was performed and assessed by the 15-member expert panel. Two separate panel meetings were convened and followed by a writing, editorial, and review process.

CONCLUSIONS

The main goal of empiric treatment in postsurgical patients with suspected gram-positive infections is to improve clinical status. Empiric therapy should be initiated at the earliest sign of infection in all critically ill patients. The choice of therapy should flow from beta-lactams to vancomycin to parenteral linezolid or quinupristin-dalfopristin. In patients likely to be discharged, oral linezolid is an option. Antibiotic resistance is an important issue, and in developing treatment algorithms for reduction of resistance, the utility of these new antibiotics may be extended and reduce morbidity and mortality.

Community-acquired Methicillin-resistant Staphylococcus aureus: Epidemiology and Potential Virulence Factors

Methicillin-resistant Staphylococcus aureus (MRSA) has been isolated from patients in the community. Some of these strains may have origins in the hospital, but others appear to be novel and unrelated to known hospital strains. Community MRSA strains have several distinguishing characteristics that may enable them to more readily colonize and infect otherwise healthy individuals. This article reviews recent publications addressing the epidemiology of MRSA in the community, risk factors associated with carriage, potentially associated virulence factors, and concepts of strain fitness as they pertain to MRSA. MRSA likely will be an increasingly important pathogen in the community.

Management of Severe Sepsis: Integration of Multiple Pharmacologic Interventions

Severe sepsis is an infection-induced process that often promotes organ dysfunction and death in up to 50% of afflicted patients. Clinical advances that improve patient survival include early goal-directed volume resuscitation, broad-spectrum empiric antimicrobial therapy with deescalation strategies, therapy with drotrecogin alfa (activated), glucocorticoid replacement in patients with adrenal insufficiency, and tight control of blood glucose levels. The challenge for critical care practitioners is to integrate the many pharmacologic and supportive interventions required for optimal care of these patients.

Poststernotomy mediastinitis due to methicillin-resistant Staphylococcus aureus endemic in a hospital

The objective of this study was to determine the incidence of and risk factors for poststernotomy mediastinitis (PSM) due to methicillin-resistant Staphylococcus aureus (MRSA) infection in a hospital in which MRSA was endemic. A retrospective case-control study of patients with PSM after cardiac surgery during January 1997 through July 2002 was conducted. The incidence of PSM was 1.01% (48 of 4746 patients), and 31 episodes (64.6%) were due to MRSA infection. We analyzed the findings for 48 case and 65 control patients. Univariate analysis revealed that the risk factors for PSM were previous hospitalization, resternotomy, chronic renal insufficiency, longer operation time, postoperative heart failure, postoperative renal failure, and reoperation for bleeding. Multivariate analysis revealed that the independent risk factors for PSM were previous hospitalization and reoperation for bleeding. Previous hospitalization was the only significant risk factor for PSM due to MRSA infection. The hospital mortality rate associated with PSM was 41.7%, and there was a higher mortality rate associated with PSM due to MRSA infection.

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.

Surgical site infections associated with methicillin-resistant Staphylococcus aureus: do postoperative factors play a role?

Patients with surgical site infections (SSIs) who underwent surgery during the period of September 1997 through December 1999 and January through July 2001 were retrospectively studied to compare patients infected with methicillin-resistant Staphylococcus aureus (MRSA) with those infected with organisms other than MRSA. Of patients with SSI who had known culture results, 77 (28.5%) of 270 had cultures that yielded MRSA. On univariate analysis, age of >or=70 years, duration of surgery of >or=4 h, duration of postoperative antibiotic treatment of >1 day, and discharge to a long-term care facility (LTCF) were significantly associated with MRSA SSI (P<.05 for all). On multivariate analysis, only discharge to an LTCF (odds ratio [OR], 2.3; P=.04) and duration of postoperative antibiotic treatment of >1 day (OR, 2.0; P=.03) were significantly associated with MRSA SSI; there was also a trend toward MRSA SSI being associated with use of a surgical drain for >1 day (P=.078). Postoperative factors may play a more important role in the causation of MRSA SSI than has previously been appreciated.

Changing spectrum of infective endocarditis: review of 194 episodes over 20 years

A review of admission records identified 194 episodes of infective endocarditis (IE) from January 1980 to December 1999 at a community hospital in Tokyo. The cases were divided into decades, and the clinical picture and short-term outcomes were compared and analyzed. The mean age of patients in the 1990s was older (45.5 +/-13.2 vs 55.1+/-12.6 years, p<0.001), and prosthetic valve endocarditis was significantly more frequently seen (14.4% vs 31.8%, p=0.004). None had a history of intravenous drug abuse (IVDA). Patients on chronic hemodialysis comprised 5.8% of IE cases in the 90s. Overall, dental procedure or caries still remained the main presumed source of infection. Staphylococcal IE showed a tendency to increase, and methicillin-resistant staphylococcal IE was significantly prominent in the 90s (0% vs 10.4%, p=0.0006). The overall in-hospital mortality was similar between the 2 groups (13.6% vs 18.8%, NS). Multivariate analysis found neurological abnormality, renal insufficiency and staphylococcal IE as predictors of in-hospital mortality. The characteristics of IE in Japan have changed, even among non-IVDA patients, and it appears to occur in a more high-risk patient population, which may warrant a more aggressive therapeutic approach to its management and treatment.

Age-related trends in pathogen frequency and antimicrobial susceptibility of bloodstream isolates in North America: SENTRY Antimicrobial Surveillance Program, 1997-2000

We report age-related trends in pathogen frequency and antimicrobial susceptibility from 25,745 bloodstream infections (BSI) due to bacterial pathogens reported from medical centres participating in the North American SENTRY Antimicrobial Surveillance Program between January 1997 and September 2000. Staphylococcus aureus, Escherichia coli and coagulase-negative staphylococci (CoNS) were the most common pathogens, together accounting for 55% of all BSI pathogens during this time period. Among nosocomial BSI, CoNS were the most frequently isolated pathogens in infants less than 1 year of age, but S. aureus increased in frequency with increasing age. Among community-onset BSI pathogens, Streptococcus pneumoniae was the most frequently reported pathogen causing BSI in patients aged 1-5, S. aureus among those aged 6-64, and E. coli predominated at the extremes of age (less than 1 year and > or = 65 years of age). Among key organism: antimicrobial agent combinations evaluated, oxacillin resistance in S. aureus increased with increasing age; conversely, oxacillin resistance among CoNS was highest among children 5 years of age or younger. Penicillin resistance among S. pneumoniae BSI was highest in children younger than 5 years, while vancomycin resistance among Enterococcus spp. predominated among nosocomial BSI in patients over 50 years of age. Important age-related differences exist in species distribution and antimicrobial susceptibility of pathogens causing BSI. This information should be helpful for clinicians as they consider empirical antimicrobial therapy for patients with suspected BSI across the age continuum.