Central line-associated bloodstream infection: is the hospital epidemiology of methicillin-resistant Staphylococcus aureus relevant?

Epidemiology of bloodstream infections caused by methicillin-resistant Staphylococcus aureus at a tertiary care hospital in New York

BACKGROUND

In the United States, bloodstream infections (BSIs) are predominated by Staphylococcus aureus. The proportion of community-acquired methicillin-resistant S aureus (MRSA) BSI is on the rise. The goal of this study is to explore the epidemiology of BSI caused by S aureus within Staten Island, New York.

METHODS

This is a case-case-control study from April 2012-October 2014. Cases were comprised of patients with BSI secondary to MRSA and methicillin-sensitive S aureus (MSSA). The control group contained patients who were hospitalized during the same time period as cases but did not develop infections during their stay. Two multivariable models compared each group of cases with the uninfected controls.

RESULTS

A total of 354 patients were analyzed. Infections were community acquired in 76% of cases. The major source of BSI was skin-related infections (n = 76). The first multivariable model showed that recent central venous catheter placement was an independent infection risk factor (odds ratio [OR] = 80.7; 95% confidence interval [CI], 2.2-3,014.1). In the second model, prior hospital stay >3 days (OR = 4.1; 95% CI, 1.5-5.7) and chronic kidney disease (OR = 3.0; 95% CI, 1.01-9.2) were uniquely associated with MSSA. Persistent bacteremia, recurrence, and other hospital-acquired infections were more likely with MRSA BSI than MSSA BSI.

CONCLUSION

Most infections were community acquired. The presence of a central venous catheter constituted a robust independent risk factor for MRSA BSI. Patients with MRSA BSI suffered worse outcomes than those with MSSA BSI.

Staphylococcus aureus infections: epidemiology, pathophysiology, clinical manifestations, and management

Staphylococcus aureus is a major human pathogen that causes a wide range of clinical infections. It is a leading cause of bacteremia and infective endocarditis as well as osteoarticular, skin and soft tissue, pleuropulmonary, and device-related infections. This review comprehensively covers the epidemiology, pathophysiology, clinical manifestations, and management of each of these clinical entities. The past 2 decades have witnessed two clear shifts in the epidemiology of S. aureus infections: first, a growing number of health care-associated infections, particularly seen in infective endocarditis and prosthetic device infections, and second, an epidemic of community-associated skin and soft tissue infections driven by strains with certain virulence factors and resistance to β-lactam antibiotics. In reviewing the literature to support management strategies for these clinical manifestations, we also highlight the paucity of high-quality evidence for many key clinical questions.

Does antimicrobial use density at the ward level influence monthly central line-associated bloodstream infection rates?

The aim of this study was to elucidate risk factors, including ward antimicrobial use density (AUD), for central line-associated bloodstream infection (CLABSI) as defined by the Centers for Disease Control and Prevention in a 430-bed community hospital using central venous lines with closed-hub systems. We calculated AUD as (total dose)/(defined daily dose × patient days) ×1,000 for a total of 20 drugs, nine wards, and 24 months. Into each line day data, we inputed AUD and device utilization ratios, number of central line days, and CLABSI. The ratio of susceptible strains in isolates were subjected to correlation analysis with AUD. Of a total of 9,997 line days over 24 months, CLABSI was present in 33 cases (3.3 ‰), 14 (42.4%) of which were on surgical wards out of nine wards. Of a total of 43 strains isolated, eight (18.6%) were methicillin-resistant Staphylococcus aureus (MRSA); none of the MRSA-positive patients had received cefotiam before the onset of infection. Receiver-operating characteristic analysis showed that central line day 7 had the highest accuracy. Logistic regression analysis showed the central line day showed an odds ratio of 5.511 with a 95% confidence interval of 1.936–15.690 as did AUD of cefotiam showing an odds ratio of 0.220 with 95% confidence interval of 0.00527–0.922 (P=0.038). Susceptible strains ratio and AUD showed a negative correlation (R²=0.1897). Thus, CLABSI could be prevented by making the number of central line days as short as possible. The preventative role of AUD remains to be investigated.

Gender differences in risk of bloodstream and surgical site infections

BACKGROUND

Identifying patients most at risk for hospital- and community-associated infections is one essential strategy for preventing infections.

OBJECTIVE

To investigate whether rates of community- and healthcare-associated bloodstream and surgical site infections varied by patient gender in a large cohort after controlling for a wide variety of possible confounders.

DESIGN

Retrospective cohort study.

PARTICIPANTS

All patients discharged from January 1, 2006 through December 31, 2008 (133,756 adult discharges and 66,592 pediatric discharges) from a 650-bed tertiary care hospital, a 220-bed community hospital, and a 280-bed pediatric acute care hospital within a large, academic medical center in New York, NY.

MAIN MEASURES

Data were collected retrospectively from various electronic sources shared by the hospitals and linked using patients' unique medical record numbers. Infections were identified using previously validated computerized algorithms.

KEY RESULTS

Odds of community-associated bloodstream infections, healthcare-associated bloodstream infections, and surgical site infections were significantly lower for women than for men after controlling for present-on-admission patient characteristics and events during the hospital stay [odds ratios (95 % confidence intervals) were 0.85 (0.77-0.93), 0.82 (0.74-0.91), and 0.78 (0.68-0.91), respectively]. Gender differences were greatest for older adolescents (12-17 years) and adults 18-49 years and least for young children (<12 years) and older adults (≥ 70 years).

CONCLUSIONS

In this cohort, men were at higher risk for bloodstream and surgical site infections, possibly due to differences in propensity for skin colonization or other anatomical differences.

Association between risk of bloodstream infection and duration of use of totally implantable access ports and central lines: a 24-month study

BACKGROUND

Prolonged use of totally implantable access ports (APs) and central lines (CLs) has been known to carry a risk of bloodstream infection (BSI), but the safe cutoff day for discontinuing use remains unknown. We performed a receiver operating characteristic (ROC) curve analysis to determine this cutoff.

METHODS

A retrospective 24-month study covered a total of 22,481 days of device use. For each day of use, the following findings were recorded: patient age and sex; presence or absence of diabetes mellitus, preexisting sepsis, and renal disease; and occurrence of device-associated BSI. BSI was defined in accordance with the Centers for Disease Control and Prevention's definition of catheter-related infection.

RESULTS

BSIs occurred in 81 patients with an AP, for a BSI rate of 2.81 cases per 1,000 days of use. Among the 896 patients with a CL, the BSI rate was 5.60 cases per 1,000 days of use. The ROC analysis found a cutoff time of 33 days for APs (median days of use, 48) and 10 days for CLs (median days of use, 20.5). For the total 22,481 days of use, the odds ratio between APs and CLs with respect to BSI was 0.556 (95% confidence interval [CI], 0.256-1.208; P = .138). Days of use beyond the cutoff had an odds ratio of 2.867 (95% CI, 1.823-4.507; P < .001). Among the risk factors, preexisting sepsis had an odds ratio of 7.843 (95% CI, 4.666-13.184; P < .001).

CONCLUSION

Use of an AP for more than 33 days and a CL for more than 10 days may carry an increased risk of device-associated BSI. These cutoff periods are longer than those expected at the time of device placement and indicate the importance of postplacement care.