Methicillin-resistant Staphylococcus aureus bacteraemia and mortality in a teaching hospital

What Is the Optimal Follow-up Length for Mortality in Staphylococcus aureus Bacteremia? Observations From a Systematic Review of Attributable Mortality

Background

Deaths following Staphylococcus aureus bacteremia (SAB) may be related or unrelated to the infection. In SAB therapeutics research, the length of follow-up should be optimized to capture most attributable deaths and minimize nonattributable deaths. We performed a secondary analysis of a systematic review to describe attributable mortality in SAB over time.

Methods

We systematically searched Medline, Embase, and Cochrane Database of Systematic Reviews from 1 January 1991 to 7 May 2021 for human observational studies of SAB. To be included in this secondary analysis, the study must have reported attributable mortality. Two reviewers extracted study data and assessed risk of bias independently. Pooling of study estimates was not performed due to heterogeneity in the definition of attributable deaths.

Results

Twenty-four observational cohort studies were included. The median proportion of all-cause deaths that were attributable to SAB was 77% (interquartile range [IQR], 72%–89%) at 1 month and 62% (IQR, 58%–75%) at 3 months. At 1 year, this proportion was 57% in 1 study. In 2 studies that described the rate of increase in mortality over time, 2-week follow-up captured 68 of 79 (86%) and 48 of 57 (84%) attributable deaths that occurred by 3 months. By comparison, 1-month follow-up captured 54 of 57 (95%) and 56 of 60 (93%) attributable deaths that occurred by 3 months in 2 studies.

Conclusions

The proportion of deaths that are attributable to SAB decreases as follow-up lengthens. Follow-up duration between 1 and 3 months seems optimal if evaluating processes of care that impact SAB mortality.

Clinical Trials Registration

PROSPERO CRD42021253891.

The safety and efficacy of high versus low vancomycin trough levels in the treatment of patients with infections caused by methicillin-resistant Staphylococcus aureus: a meta-analysis

BACKGROUND

Recent guidelines have recommended vancomycin trough levels of 15-20 mg/L for treatment of serious infections caused by methicillin-resistant Staphylococcus aureus (MRSA). However, high trough levels may increase risk of nephrotoxicity and mortality, and high vancomycin trough levels have not been well studied. This study was designed to combine safety and efficacy results from independent studies and to compare between high and low vancomycin trough levels in the treatment of MRSA-infected patients using meta-analysis.

METHODS

From 19 eligible studies, 9 studies were included in meta-analysis to compare clinical success between high and low vancomycin trough levels, while 10 and 11 studies met criteria for comparing trough levels and nephrotoxicity and trough levels and mortality, respectively. The PubMed/Medline, Web of Science, and Scopus databases, and hand searching were used to identify eligible studies dated up to March 2016. Of 2344 subjects with MRSA infection, 1036 were assigned to trough levels ≥15 mg/L and 1308 to trough levels <15 mg/L.

RESULTS

High vancomycin trough levels were found to be associated with risk of nephrotoxicity (odds ratio [OR] 2.14, 95 % confidence interval [CI] 1.42-3.23 and adjusted OR 3.33, 95 % CI 1.91-5.79). There was no evidence of difference between high and low vancomycin trough levels for mortality (OR; 1.09; 95 % CI 0.75-1.60) or clinical success (OR 1.07; 95 % CI 0.68-1.68).

CONCLUSION

In this study, high vancomycin trough levels were identified as an independent factor associated with risk of nephrotoxicity in MRSA-infected patients. Association between vancomycin trough levels and both adverse effects and clinical outcomes requires further study.

Management and outcomes in patients with Staphylococcus aureus bacteremia after implementation of mandatory infectious diseases consult: a before/after study

Background

Infectious disease (ID) consultations have been shown to increase adherence to guidelines and decrease mortality for patients with Staphylococcus aureus bacteremia (SAB). Here, we assessed the impact of a mandatory ID consultation policy for SAB.

Methods

We retrospectively reviewed all consecutive adult patients with SAB at two tertiary care teaching hospitals in Hamilton, ON, Canada. Mandatory ID consults for SAB were implemented on January 1^st 2012. We compared SAB cases in 2011 (control group) with those in 2012 (intervention group). Outcomes included adherence to the Infectious Diseases Society of America guidelines and patient outcomes.

Results

We reviewed 128 SAB cases in 2011 and 124 in 2012. The majority of S. aureus were methicillin-susceptible (97/128, 75.8 % in 2011 and 100/124, 80.6 % in 2012). ID involvement increased significantly from 93/128 (72.7 %) in 2011, to 103/124 (83.1 %) in 2012 (odds ratio [OR] 1.9, 95 % confidence interval [CI] 1.1–3.3, p = 0.047). There was also a significant decrease in the median time to ID involvement from 2 days to 1 (p = 0.001). In patients who survived the minimum treatment course (greater than 13 days), there was a significant improvement in adherence to IDSA guidelines in 2012 (65/102, 63.7 % vs. 77/96, 80.2 %; OR 2.3, 95 % CI 1.2–4.4, p = 0.01). Mortality and SAB relapse rates were similar in both groups.

Conclusions

Creating an automated ID consultation for SAB led to an increase in involvement of ID, a significant decrease in time to ID involvement, and better adherence to IDSA guidelines. The study was not sufficiently powered to detect significant changes in mortality and SAB relapse rates.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-015-1296-y) contains supplementary material, which is available to authorized users.

The clinical significance of vancomycin minimum inhibitory concentration in Staphylococcus aureus infections: a systematic review and meta-analysis

BACKGROUND

Emerging data suggest that vancomycin may be less effective against serious methicillin-resistant Staphylococcus aureus (MRSA) infections with minimum inhibitory concentration (MIC) values at the higher end of the susceptibility range. The purpose of this review is to examine the strength of these associations.

METHODS

All relevant studies pertaining to treatment outcomes or mortality associated with vancomycin MIC were retrieved from the medical literature from January 1996 through August 2011 and analyzed according to Cochrane guidelines.

RESULTS

Of the 270 studies identified, 48 studies were reviewed, with 22 studies included in the final meta-analysis. Vancomycin MIC was significantly associated with mortality for MRSA infection irrespective of the source of infection or MIC methodology (odds ratio [OR], 1.64; 95% confidence interval [CI], 1.14-2.37; P < .01). This mortality association was predominantly driven by bloodstream infections (BSIs; OR, 1.58; 95% CI, 1.06-2.37; P = .03) and isolates with a vancomycin MIC of 2 μg/mL by Etest (OR, 1.72; 95% CI, 1.34-2.21; P < .01). Vancomycin MIC was significantly associated with treatment failure irrespective of source of infection or MIC methodology (OR, 2.69; 95% CI, 1.60-4.51; P < .01).

CONCLUSION

High vancomycin MIC was associated with a higher mortality rate in MRSA BSI. Thus, institutions should consider conducting Etest MICs on all MRSA BSI isolates. Although these data highlight concerns about vancomycin, currently, there are no data to support better survival rates with alternative antibiotics. Data are sorely needed to determine whether other agents can remedy these outcomes observed with vancomycin for MRSA infections with elevated vancomycin MIC values.

Community-associated methicillin-resistant Staphylococcus aureus bacteremia and endocarditis among HIV patients: a cohort study

BACKGROUND

HIV patients are at increased risk of development of infections and infection-associated poor health outcomes. We aimed to 1) assess the prevalence of USA300 community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) among HIV-infected patients with S. aureus bloodstream infections and. 2) determine risk factors for infective endocarditis and in-hospital mortality among patients in this population.

METHODS

All adult HIV-infected patients with documented S. aureus bacteremia admitted to the University of Maryland Medical Center between January 1, 2003 and December 31, 2005 were included. CA-MRSA was defined as a USA 300 MRSA isolate with the MBQBLO spa-type motif and positive for both the arginine catabolic mobile element and Panton-Valentin Leukocidin. Risk factors for S. aureus-associated infective endocarditis and mortality were determined using logistic regression to calculate odds ratios (OR) and 95% confidence intervals (CI). Potential risk factors included demographic variables, comorbid illnesses, and intravenous drug use.

RESULTS

Among 131 episodes of S. aureus bacteremia, 85 (66%) were MRSA of which 47 (54%) were CA-MRSA. Sixty-three patients (48%) developed endocarditis and 10 patients (8%) died in the hospital on the index admission Patients with CA-MRSA were significantly more likely to develop endocarditis (OR = 2.73, 95% CI = 1.30, 5.71). No other variables including comorbid conditions, current receipt of antiretroviral therapy, pre-culture severity of illness, or CD4 count were significantly associated with endocarditis and none were associated with in-hospital mortality.

CONCLUSIONS

CA-MRSA was significantly associated with an increased incidence of endocarditis in this cohort of HIV patients with MRSA bacteremia. In populations such as these, in which the prevalence of intravenous drug use and probability of endocarditis are both high, efforts must be made for early detection, which may improve treatment outcomes.

Relationships between vancomycin minimum inhibitory concentration, dosing strategies, and outcomes in methicillin-resistant Staphylococcus aureus bacteremia

Retrospective study aimed to examine outcomes of methicillin-resistant Staphylococcus aureus (MRSA) bacteremia in relationship to vancomycin minimum inhibitory concentration (VAN MIC) and serum trough concentrations among subjects who had ≥1 blood culture positive for MRSA between April 2008 and August 2009. Treatment failure occurred in 7/24 (29%) subjects with VAN MIC = 2 mg/L versus 20/94 (21%) subjects with VAN MIC ≤1.5 mg/L (adjusted OR 1.11, 95% confidence interval [CI] 0.24-5.14). Among subjects who had documented VAN serum trough concentrations, treatment failure occurred in 5/26 (19%) subjects with concentrations <15 mg/L versus 18/68 (27%) subjects with concentrations ≥15 mg/L (adjusted OR 0.91, 95% CI 0.21-3.84). In conclusion, treatment outcomes were similar regardless of VAN MIC, although there was a non-statistically significant trend towards decreased clinical efficacy among patients with VAN MIC = 2 mg/L. Optimization of VAN pharmacokinetic indices did not appear to correlate with clinical responses.

The value of infectious diseases consultation in Staphylococcus aureus bacteremia

BACKGROUND

Staphylococcus aureus bacteremia results in substantial mortality. Infectious diseases specialist consultation can improve adherence to evidence-based management of S. aureus bacteremia, but its effect on mortality is unclear.

METHODS

A 2-year prospective cohort study of patients with S. aureus bacteremia was performed at a large tertiary care hospital. Patients who died within 2 days of diagnosis were excluded. Independent risk factors for 28-day mortality were determined.

RESULTS

Among 341 patients with S. aureus bacteremia, 189 (55%) were male, 196 (58%) were Caucasian, 185 (54%) had methicillin-resistant S. aureus, 108 (32%) had nosocomial bacteremia, and 231 (68%) had a central venous catheter at the time of diagnosis. The median age was 56 years (range 22-95 years). A total of 111 patients (33%) had an infectious diseases consultation. Fifty-four patients (16%) died within 28 days after diagnosis. Factors associated with mortality were intensive care unit admission 48 hours or less after the first positive blood culture (adjusted hazard ratio, 4.65; 95% confidence interval [CI], 2.65-8.18), cirrhosis (adjusted hazard ratio, 4.44; 95% CI, 2.40-8.20), and advanced age (adjusted hazard ratio, 1.27 per every 10 years of age; 95% CI, 1.08-1.50). Infectious diseases consultation was associated with a 56% reduction in 28-day mortality (adjusted hazard ratio, 0.44; 95% CI, 0.22-0.89).

CONCLUSION

Only one third of patients with S. aureus bacteremia in this cohort had an infectious diseases specialist consultation. Infectious diseases consultation was independently associated with a reduction in 28-day mortality. Routine infectious diseases consultation should be considered for patients with S. aureus bacteremia, especially those with greater severity of illness or multiple comorbidities.