Clinical Infectious Diseases Advance Access published June 16, 2015
1 Vancomycin combined with clindamycin for the treatment of acute bacterial skin
Kurt A. Wargo1, Erin K. McCreary1, Thomas M. English2 1Auburn
University Harrison School of Pharmacy, USA
2University
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and skin-structure infections
of Massachusetts Medical School, USA, Department of Quantitative Health
Sciences
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Associate Clinical Professor, Auburn University Harrison School of Pharmacy, 301
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Governors Dr. SW, Suite 385 C1, Huntsville, AL 35801, 256-426-7268,
[email protected] Alternate Author Contact Information: Erin K. McCreary, Pharm.D. 9308 Standerwick Lane,
Article Summary:
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Huntersville, NC 28078, 484-515-9589,
[email protected] In this retrospective analysis of patients with acute bacterial skin and skin-structure
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infections, the combination of vancomycin and clindamycin decreased hospital length of stay for patients with an abscess and 90-day readmission rates for all patients compared to
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vancomycin monotherapy.
© The Author 2015. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail:
[email protected].
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Corresponding Author Contact Information: Kurt A. Wargo, Pharm.D., BCPS (AQ-ID),
2 Abstract
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Background: Acute bacterial skin and skin-structure infections (ABSSSI) are common causes of hospital admissions. These infections are often caused by methicillin-resistant S. aureus (MRSA), therefore vancomycin remains a commonly used therapy. The purpose of this study was to compare hospital length of stay (LOS) in patients treated with
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Methods: This was a retrospective analysis of 269 patients admitted with ABSSSI to a 941bed hospital in North Alabama, USA. Patients who received either vancomycin monotherapy or in combination with clindamycin were included. The primary outcome
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was hospital LOS, while secondary outcomes included 90-day readmission rate and the impact of the following on the primary outcome: organisms cultured, presence of abscess,
diabetes.
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incision and debridement (I&D), failure of a trial of outpatient antibiotics, and presence of
Results: Hospital LOS was similar between groups when evaluating all ABSSSI (3.7 ± 1.5
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vs. 4.0 ± 2.0 days, p = 0.192, combination and monotherapy, respectively). In patients with abscesses, combination therapy was significantly associated with decreased LOS by 18.2%
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compared to monotherapy (95% CI, 0.818 [0.679 – 0.985]; p = 0.034). Among the entire population, significantly less patients in the combination group were readmitted within 90 days (5.3% vs. 15.3%, p = 0.006; OR 3.2, 95% CI [1.35 – 7.66]). 90-day readmission rates were significantly less among patients with abscesses as well (2.0% vs. 24.3%, p = 0.0001; OR 14.6, 95% CI [2.98 – 71.37]).
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vancomycin monotherapy versus combination therapy with clindamycin for ABSSSI.
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Conclusions: Combination therapy with vancomycin and clindamycin was associated with
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decreased hospital LOS for patients with an abscess. The 90-day hospital readmission rates for ABSSSI may be reduced when combination therapy is utilized. A larger, prospective, multi-centered study is needed to validate these findings.
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Acute bacterial skin and skin-structure infections (ABSSSI) are among the most common
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infectious causes of hospital admissions. Gram-positive pathogens such as Staphylococcus aureus and Streptococcus spp. are largely responsible for the majority of ABSSSI with rates
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of hospitalization increasing substantially and rapidly.1 From 1993 to 2005 there was an increase in annual emergency department (ED) visits for ABSSSI from 1.2 million to 3.4 million visits.2 Furthermore, it was determined that admissions for ABSSSI increased by
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nearly 30%, while admissions for infections such as pneumonia remained stable, indicating that ABSSSI are a critical rising health concern.3 In a study of 11 EDs, it was estimated that 76% of all ABSSSI were due to methicillin-resistant Staphylococcus aureus (MRSA).4 Considering the majority of S. aureus isolates are methicillin-resistant, it is recommended
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that patients with risk factors, or with purulent ABSSSI, receive empirical therapy for
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MRSA.5,6
Vancomycin remains the standard empirical therapy for MRSA infections globally.5,7,8 Considering the increasing resistance rates of MRSA to vancomycin, the Infectious Diseases Society of America launched the ‘10 × '20 campaign in order to encourage development of
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Background
4 new antibiotics to treat a wide variety of antimicrobial-resistant infections, including those caused by MRSA.9 In 2014 alone, three agents (tedizolid, oritavancin, and dalbavancin)
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were approved for the treatment of MRSA ABSSSI infections; however, they are costly alternatives and accordingly their role in therapy is yet to be determined.10
New antimicrobial agents are needed for these infections, but currently available agents
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especially in the presence of an abscess. Abscesses complicate the treatment of ABSSSI,
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with current guidelines recommending up to 14 days of antimicrobial therapy.6 Appropriate incision and drainage (I & D) is the primary treatment for an abscess, but
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adjunctive antimicrobial therapy is also recommended in the presence of extensive disease, concomitant cellulitis, immunosuppression, extreme age, and/or incomplete drainage or lack of response to the debridement procedure.6 It has been hypothesized that antibiotics
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provide incremental benefit over drainage alone for cutaneous abscesses, which may be due to a lesser-known phenomenon, known as the Eagle or inoculum effect.1,11
The Eagle effect was first observed in 1954 when Dr. Harry Eagle described the limitations
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of penicillins in toxin-mediated streptococcal infections with high stagnant bacterial concentration.11 He observed that infections with a large amount of bacteria (such as an
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abscess) are in a stationary-growth phase. As these organisms are not actively dividing, beta-lactam and glycopeptide antibiotics are rendered relatively ineffective. However, the
incorporation of antibiotics which disrupt protein synthesis may improve abscess penetration, cease toxin production, and cause the bacteria to begin actively replicating.12-
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can be utilized in ways not previously thought in order to successfully manage ABSSSIs,
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Therefore, this alteration of protein synthesis may increase the efficacy of previously
ineffective beta-lactam or glycopeptide antibiotics when utilized as combination therapy.12This study was designed to examine the effect of synergy between the glycopeptide
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vancomycin and the lincosamide protein synthesis inhibitor clindamycin on clinical
outcomes. The primary purpose of this study was to compare the mean hospital length of stay (LOS) in patients with ABSSSI that were treated with vancomycin and clindamycin
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Methods
This was an institutional review board approved, retrospective review of patients admitted
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to a 941-bed tertiary, regional referral hospital in Northern Alabama between January 2010 and December 2013 with diagnostic related group numbers related to ABSSSI. Patients were included if they were diagnosed with an ABSSSI, 19 years or older, and
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received either vancomycin monotherapy or in combination with clindamycin for a minimum of 48 hours from the onset of IV antibiotic therapy. Patients could receive antibiotics in addition to the study antibiotics if those agents did not have activity against MRSA and MRSA was ultimately cultured. Patients were excluded from the study if they
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did not meet the above criteria, had a diagnosis other than ABSSSI such as diabetic foot infection, osteomyelitis, septic arthritis, or necrotizing fasciitis, or if antibiotic therapy
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changed during the course of hospitalization, such that the study antibiotics were no longer administered.
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combination therapy versus vancomycin monotherapy.
6 The primary outcome of the study was hospital LOS. The secondary outcome was any infection-related 90-day hospital readmission as determined by admission diagnosis and
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confirmed by discharge summary. With respect to those outcomes, variables such as
outpatient antibiotic prescriptions given prior to admission, MRSA cultures, status of
incision and debridement of an abscess, and comorbid diabetes were also examined to determine impact on LOS or 90-day readmission. Other variables examined included
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(AKI), and rates of Clostridium difficile-associated diarrhea (CDAD). Discharge antibiotics
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were determined by prescriber’s discharge instructions and hospital discharge medication record form. For patients with infections caused by MRSA, the MIC was determined
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through MicroScan PROMPT® (3M Company, St. Paul, Minnesota). Reports of the MIC were given as less than 1 mg/L, 1 mg/L, and 2 mg/L. When the MIC was 2 mg/L, the result was confirmed using MicroScan Turbidity testing (Siemens, Inc., Malvern, PA). AKI was defined
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as an increase in serum creatinine (CrS) by at least 1.5 times baseline, and CDAD was defined as the detection of C. difficile via polymerase chain reaction in symptomatic patients.15
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A sample of 267 patients was needed in order to provide 90% power with a two-sided alpha of 0.05. All parametric data were initially analyzed using Student’s t test. All
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categorical variables and proportions were analyzed using chi-squared. Upon determination of statistical significance, a general linear model with a Poisson log link was employed to compare monotherapy and combination therapy on length of stay as has been
suggested previously.16 Due to a small sample size, we used backward stepwise selection
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discharge antibiotics, susceptibility patterns of MRSA, incidence of acute kidney injury
7 (entry and stay = 0.1) process evaluating treatment, I & D status, diabetes, outpatient antibiotics, and corticosteroid therapy. For the secondary outcome of 90-day readmission,
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once statistical significance was determined, a manual logistic regression was conducted to determine variables that may have been impacted readmission including combination
therapy, I & D status, diabetes, and outpatient antibiotics received prior to admission. Not all patients had positive culture data; therefore those with positive MRSA cultures were
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demographics in those patients. In this population, backward stepwise selection (entry
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and stay = .1) linear regression using the variables of treatment, diabetes, abscess, and I & D status was completed to assess impact on hospital LOS. Manual logistic regression, using
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the same variables, was done to assess impact on 90-day readmissions. Fisher’s Exact Test was used to determine differences in adverse effect outcomes between the two groups. All statistical analyses were performed with the use of SPSS software, version 22 (IBM
Results
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Corporation).
A total of 594 patients with ABSSSI were screened, 269 of which met criteria for inclusion
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in this study. Reasons for exclusion can be seen in detail in Appendix A. Demographics were similar between the groups, with the exceptions that patients in the monotherapy
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group were approximately five years older than the combination group, had a higher percentage of diabetes, and a higher percentage of MRSA infections (Table 1). Significantly
more patients in the combination group received I & D.
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analyzed in a separate analysis utilizing chi-square to determine differences in
8 Primary outcome Among the entire study population, a decrease in LOS (Table 2) was not statistically
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significantly associated with combination therapy, (3.7 ± 1.4 vs. 4.0 ± 2.0 days; 95%CI, -
0.32 [-0.74 – 0.10]; p = 0.137). However, in the subgroup of patients that presented with an abscess, LOS was statistically significantly decreased with combination therapy (3.6 ± 1.5 vs. 4.4 ± 2.3 days; 95%CI, -0.82 [-1.49 – -0.15]; p = 0.016). Among the patients with an
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diabetes, outpatient antibiotics, and corticosteroid therapy demonstrated that only
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combination therapy was associated with a significant decrease in LOS by 18.2% compared
Secondary Outcomes 90-day Hospital Readmission
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to monotherapy (95% CI, 0.818 [0.679 – 0.985]; p = 0.034) (Table 3).
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In the entire study population, a total of 23 patients (9%) were readmitted for infectionrelated causes within 90 days of discharge. A significantly lower rate of readmission was observed in patients that received combination therapy with vancomycin and clindamycin compared to those that received vancomycin monotherapy for the entire cohort, as well as
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for the sub-group with abscesses (Table 4). Manual logistic regression was conducted to determine if presence of diabetes, incision and debridement (I&D), and antibiotic therapy
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prior to admission also contributed to the lower rate of readmissions in both patients with abscesses and all ABSSSI (Table 4). In the entire population, only treatment with combination therapy was found to be associated with fewer readmissions. Patients
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abscess, a generalized linear model with Poisson log link evaluating treatment, I & D status,
9 receiving combination therapy were 69% less likely to be readmitted than patients
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receiving monotherapy (p = 0.009).
In the sub-group of patients with abscesses, both combination therapy and incision and debridement were found to decrease 90-day readmission rates (Table 5). Of the nine
patients that were readmitted with abscesses, seven received monotherapy whereas only
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received I&D; four monotherapy patients and one combination therapy patient, for a total
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of five patients receiving I&D versus four patients that did not receive I&D in the total subgroup population. Patients with abscesses treated with combination therapy were
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88.5% less likely to be readmitted than patients receiving monotherapy (p = 0.011). Patients who had I&D were 86% less likely to be readmitted than patients without I&D (p =
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0.017).
Methicillin-Resistant Staphylococcus aureus A total of 146 patients (54%) had positive infection site cultures. The most common organism isolated was MRSA, which was responsible for 102 (70%) of the ABSSSI in the
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study population, with 64 in the combination group and 38 in the monotherapy group. The majority of patients with MRSA infections had abscesses, 53 (82%) in the combination
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group, and 29 (76%) in the monotherapy group (p = 0.638). A total of six MRSA isolates had an MIC of 2 mg/L, two (3%) in the combination group and four (10.5%) in the monotherapy group (p = 0.192). Risk factors for hospital-acquired MRSA (HA-MRSA) were evaluated in those infected with MRSA, including nursing home residency, healthcare
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two received combination therapy. Approximately half of the patients in each group
10 occupation, previous admission in the past 90 days, history of MRSA skin infections, intravenous drug abuse, and immunocompromised state. The patient was considered in an
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immunocompromised state if they received treatment with any immunosuppressive
medication (e.g. monoclonal antibody, chemotherapy, corticosteroids), or if they had
diabetes, cancer, end-stage renal disease, or any disorder of the immune system. There was no difference between treatment groups with respect to percentages of patients with or
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readmission was significantly lower in the combination group, one patient versus eight
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patients (p = 0.0014). Linear regression demonstrated no association found in LOS between the combination and monotherapy groups (3.73 ± 1.46 vs. 4.37 ± 2.33, p = 0.09).
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Logistic regression determined that only treatment with combination therapy was associated with decreased 90-day readmission rates (Table 6).
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Discharge Antibiotics
Patients in the study were discharged on a wide variety of antibiotics (Figure 2). Both treatment groups were most commonly discharged on sulfamethoxazole-trimethoprim (42% combination group, 38% in the monotherapy group). More patients in the
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combination group were discharged on clindamycin (39% vs. 15.5%, p = 0.0001). In contrast, more patients in the monotherapy group were discharged on vancomycin (11%
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vs. 3%, p = 0.006), linezolid (6% vs. 0.5%, p = 0.003), or daptomycin (2.5% vs. 0%, p = 0.025). Patients in the combination group were discharged with a significantly shorter duration of antibiotics than the monotherapy group (8.6 ± 2.8 days vs. 10.2 ± 3.73 days, p = 0.0001).
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without risk factors (Figure 1). In the subgroup of patients that cultured MRSA, 90-day
11
Safety: Acute kidney injury and Clostridium difficile-associated diarrhea
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A total of five (1.85%) patients in the entire study population experienced RIFLE class
“risk” of AKI, all of which occurred in the combination group. However, this difference was not significantly different between groups (p = 0.329). When evaluating the risk factors
associated with vancomycin-associated nephrotoxicity (VAN), it was discovered that one
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experienced an increase in CrS from 1.3 mg/dL to 2.0 mg/dL. Another patient receiving
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concomitant furosemide therapy had an increase in CrS from 0.7 mg/dL to 1.2 mg/dL . A third patient on concomitant cimetidine, received a vancomycin dose of 20 mg/kg, yielding
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a trough level of 38 mg/L, and experienced an increase in CrS from 0.5 mg/dL to 1.1 mg/dL. The final two cases of VAN could not be explained, as no risk factors were present. One patient had an increase in CrS from 0.3 mg/dL to 1.0 mg/dL (unclear if the initial 0.3 mg/dL
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was accurate as all other CrS levels ranged from 0.8 – 1.0 mg/dL), and the other had an increase in CrS from 0.8 mg/dL to 1.4 mg/dL. The average daily vancomycin dose among the entire population was 2389.6 ± 856.7 mg, correlating to an average of 14.9 ± 3.4 mg/kg/dose. A total of 82 patients (30%) had vancomycin trough levels drawn, with an
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average level of 10.5 ± 6.5 mg/L (range, 3 – 41 mg/L). No cases of C. difficile-associated diarrhea occurred in patients while receiving treatment or in the 90-day follow-up for
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either group.
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patient with chronic kidney disease receiving furosemide, indomethacin, and lisinopril
12 Discussion ABSSSI have become a common cause for hospital admissions, and MRSA is the causative
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pathogen for the majority of these admissions.1 Although newer agents are available to treat these infections, they have significantly higher acquisition costs compared to
vancomycin. We conducted this retrospective study to compare the effectiveness of two older antimicrobials in an effort to evaluate if the combination of vancomycin and
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This study demonstrated an association between treatment with a combination of
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vancomycin and clindamycin and decreased LOS for patients with abscesses, as well as
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decreased hospital readmissions in 90 days.
This study is not without limitations and warrants further investigation through a randomized, prospective study comparing the two treatment options. Due to the
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retrospective nature of the study, we relied on information gathered from patient’s medical records. As such, not all information was available. For example, we were unable to assess the actual size of the skin infections and abscesses, nor were we able to assess the success of I & D. These factors could have certainly played a role in how quickly the infection
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resolved, and consequently, hospital LOS.
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Another limitation was that we were unable to capture information about patients who
were readmitted to other institutions, or sought care outside our hospital system. This could have impacted the association we observed in decreased 90-day readmissions with the combination therapy compared to monotherapy. In addition, the relative safety of
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clindamycin decreased LOS and 90-day readmission rates compared to vancomycin alone.
13 combination therapy could be overestimated, as patients who developed CDAD may have
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sought care at another institution.
In an effort to keep a relative 2:1 ratio of combination therapy to monotherapy, certain
factors could not be controlled for in the baseline demographics. There was a difference between the groups in age, where the monotherapy group was approximately five years
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since we could not control for this discrepancy, and discovered a weak association
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(correlation coefficient = 0.237). We also could not control for the presence of concomitant diabetes or other immunocompromised states in the population. One could argue that
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patients with diabetes and those who are immunocompromised would have a longer course of illness and thus a longer LOS and greater potential for readmission. However, upon conducting linear regression, Poisson log link, and logistic regression analyses, it was
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determined that these did not impact LOS or 90-day hospital readmissions. Furthermore, these analyses showed that infections caused by MRSA were not associated with increased LOS or 90-day hospital readmissions compared to infections caused by other pathogens. On the contrary, we found that while patients with MRSA treated with combination therapy
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had no association with a decreased LOS, there was an association with less 90-day
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hospital readmissions compared to treatment with vancomycin monotherapy.
Infections caused by MRSA occurred in 102 patients in the population studied. There was no difference between the two treatment arms in the percentage of patients with risk factors for MRSA. Patients with one or fewer risk factors were more commonly observed
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older than the combination therapy group. We assessed correlation between LOS and age
14 than those having more than one risk factor. The most common risk factors demonstrated were previous MRSA skin infections and immunocompromised conditions. In addition, we
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exhibited an overall low percentage of MRSA isolates with an MIC of 2 mg/L (6%). In those patients, the LOS was found to be significantly longer than those with an MRSA MIC less
than 2 mg/L. Although these findings are based upon 6 vs. 96 isolates, it is certainly worth
A final limitation of this study was that a cost-effective analysis was not conducted. While
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it can be assumed that a decrease in length of stay would decrease overall costs, this was not an outcome evaluated. Future studies should examine this and compare the
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combination to newer agents such as daptomycin, linezolid, tedizolid, ceftaroline, and the
Conclusions
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glycopeptides dalbavancin, telavancin, and oritavancin.
Monotherapy with vancomycin along with I & D has been the standard management of ABSSSI for many years. However, our study showed that the combination of vancomycin and clindamycin is an effective and possibly better alternative than vancomycin
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monotherapy for the treatment of ABSSSI. The results of this study demonstrated that the combination of vancomycin and clindamycin were associated with a decreased LOS in
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patients with abscesses and fewer readmissions in 90-days for all ABSSSI. This treatment option should be explored further through a larger, prospective study in order to validate these results.
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exploring this association in future studies.
15 NOTES
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Conflicts of Interest: The authors of this manuscript received no funding for this work and have no conflicts of interest to disclose.
Acknowledgements: The authors would like to thank Spencer Durham, Pharm.D., BCPS
Figure Legends
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editing this manuscript.
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Figure 1. Risk factors for MRSA in combination therapy and monotherapy groups Figure 2. Antibiotics prescriptions with which patients were discharged from the hospital
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(*p < 0.05)
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(AQ-ID), Kaitlin McGinn, Pharm.D., and Ryan Owens, Pharm.D., for their assistance with
16 References 1. Jenkins TC, Sabel AL, Sarcone EE, Price CS, Mehler PS, Burman WJ. Skin and soft-tissue
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infections requiring hospitalization at an academic medical center: opportunities for antimicrobial stewardship. Clin Infect Dis. 2010;51:895-903.
2. Pallin DJ, Egan DJ, Pelletier AJ, Espinola JA, Hooper DC, Camargo CA. Increased US
Emergency Department Visits for Skin and Soft Tissue Infections, and Changes in Antibiotic
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Staphylococcus aureus. Ann Emerg Med. 2008;51:291-298.
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3. Edelsberg J, Taneja C, Zervos M, Haque N, Moore C, Reyes K, et al. Trends in US Hospital Admissions for Skin and Soft Tissue Infections. Emerg Infect Dis. 2009;15:1516-8.
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4. Moran GJ, Krishnadasan A, Gorwitz RJ, Fosheim GE, McDougal LK, Carey RB, et al. Methicillin-Resistant S. aureus Infections among Patients in the Emergency Department. N Engl J Med. 2006;355:666-74.
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5. Boucher HW, Wilcox M, Talbot GH, et al. Once-weekly dalbavancin versus daily conventional therapy for skin infection. New Engl J Med. 2014;370:2169-79. 6. Liu C, Bayer A, Cosgrove SE, et al. Clinical practice guidelines by the Infectious Diseases Society of America for the treatment of methicillin-resistant Staphylococcus
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aureus infections in adults and children. Clin Infect Dis. 2011;52(3):e18-e55. [Erratum, Clin Infect Dis 2011;53:319.]
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7. Corey GR, Kabler H, Mehra P, et al. Single-dose oritavancin in the treatment of acute bacterial skin infections. N Engl J Med. 2014;370:2180-90. 8. Dalbavancin or Ortivancin for Skin Infections. N Engl J Med. 2014;371:1160-63.
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Choices, During the Emergence of Community-Associated Methicillin-Resistant
17 9. Infectious Diseases Society of America. The 10×'20 initiative: pursuing a global commitment to develop 10 new antibacterial drugs by 2020. Clin Infect Dis. 2010;50:
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1081-3. 10. New FDA Drug Approvals.
http://www.accessdata.fda.gov/scripts/cder/ob/default.cfm. Accessed 12/22/2014.
11. Eagle H. The multiple mechanisms of penicillin resistant. J Bacteriol. 1954;68:610-16.
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Chemother. 2003;47:1752-5.
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and in Combination, on Streptococcal Pyrogenic Exotoxin A Release. Antimicrob Agents
13. Stevens DL, Gibbons AE, Bergstrom R, Winn V. The Eagle Effect Revisited: Efficacy of
Infect Dis. 1988;158:23-8.
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Clindamycin, Erythromycin, and Penicillin in the Treatment of Streptococcal Myositis. J
14. Clay AS, Behnia M. A 55-Year-Old Man With Fever, Renal Failure, and Hip Pain. Chest.
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2001;119:281–284.
15. Bellomo R, Ronco C, Kellum JA, Mehta RL, Palevsky P. Acute renal failure-definition, outcome measures, animal models, fluid therapy and information technology needs: the Second International Consensus Conference of the Acute Dialysis Quality Initiative Group.
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Crit Care. 2004;8:R204-12.
16. Verburg IWM, de Keizer NF, de Jonge E, Peek N (2014) Comparison of Regression
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Methods for Modeling Intensive Care Length of Stay. PLoS ONE 9(10): e109684. doi:10.1371/journal.pone.0109684.
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12. Coyle EA, Cha R, Rybak MJ. Influences of Linezolid, Penicillin, and Clindamycin, Alone
18
Table 1. Population Demographics
monotherapy (N = 84)
Race (n, %)
112 (60.5)
0.150
45.4 ± 17.7
0.040
74 (88)
African-American
9 (11)
22 (12)
0.305
30 (36)
40 (22)
0.015
Cellulitis
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Diabetes (n, %) Type of infection (n, %)
154 (83)
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Caucasian
88 (48)
37 (44)
97 (52)
0.202
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Abscess
47 (56)
ABX given prior to admission (n, %)
43 (51)
82 (44)
0.295
Incision and Debridement (n, %)
30 (81)
91 (94)
0.03
38 (84)
64 (64)
0.013
MSSA
5 (11)
17 (17)
0.361
Coagulase (-) Staphylococcus spp.
1 (2)
3 (3)
0.791
Streptococcus spp.
1 (2)
10 (10)
0.102
S. viridans
0 (0)
6 (6)
0.093
Mean creatinine, admission (mg/dL)
1.04 ± 0.77
0.93 ± 0.63
0.218
Mean white blood cell count, admission
11.04 ± 4.53
11.68 ± 4.69
0.296
Bacteria cultured (n, %)
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MRSA
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50.3 ± 18.7
Clindamycin
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43 (51)
Age (years)
p
(N = 185)
Gender (n, %) Male
Vancomycin and
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Vancomycin
19 (cells x 103) 2222.1 ± 907
2464.8 ± 824.3
0.918
Cumulative vancomycin dose (mg)
8273.8 ± 4228.9
8586.3 ± 4208.1
0.574
Mean 24-hour clindamycin dose (mg)
N/A
Cumulative clindamycin dose (mg)
N/A
N/A
7894.1 ± 3325.2
N/A
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2345 ± 481
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Mean 24-hour vancomycin dose (mg)
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Table 2. Comparison of hospital length of stay for all patients with ABSSSIs and those
Hospital LOS (days)
Vancomycin and
monotherapy
Clindamycin
4.0 ± 2.0
3.7 ± 1.44
4.4 ± 2.3
3.6 ± 1.5
Hospital LOS (days)
p
-0.32 (-0.74 – 0.10)
0.137
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for all ABSSSI
OR, 95% CI
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for abscesses only
-0.82 (-1.49 - -0.15)
0.016
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Vancomycin
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with abscesses.
21 Table 3. Relationship of combination therapy and LOS among patients with an abscess using a generalized linear model with Poisson log link factoring in
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treatment, I & D status, diabetes, outpatient antibiotics, and corticosteroid therapy Standard Error
Sig.
Combination Therapy
-0.201
.0781
0.034
Intercept
1.489
.0947