Failure of outpatient antibiotics among patients hospitalized for acute bacterial skin infections: What is the clinical relevance?

BACKGROUND: Infectious Diseases Society of America guidelines recommend that patients hospitalized for acute bacterial skin infections after failure of outpatient antibiotic therapy be managed as "severe" infections; however, the clinical relevance of apparent failure of outpatient therapy is not clear. METHODS: This was a secondary analysis of a multicenter, retrospective cohort of adults and children hospitalized for cellulitis, abscess, or wound infection. We compared clinical features, laboratory and microbiology findings, antibiotic treatment, and outcomes among patients who received outpatient antibiotics prior to admission and those who did not. RESULTS: Of 533 patients, 179 (34%) received outpatient antibiotics prior to admission. Compared with those who did not, patients who received antibiotics prior to admission less frequently had fever (18% vs 26%, P=.04) and leukocytosis (33% vs 51%, P<.001). In the 202 cases where a microorganism was identified, Staphylococcus aureus was more common among those who received antibiotics prior to admission (75% vs 58%, P=.02), particularly methicillin-resistant S aureus (41% vs 27%, P=.049), whereas aerobic gram-negative bacilli were less common (3% vs 13%, P=.03). After hospitalization, clinical failure occurred with similar frequency between the 2 groups (12% vs 11%, P=.73). CONCLUSIONS: Patients hospitalized with skin infections after apparently failing outpatient therapy had clinical features suggestive of less severe infection and similar outcomes compared with patients who did not receive antibiotics prior to admission. Our results suggest that inpatient treatment for patients not responding to outpatient therapy should focus on methicillin-resistant S aureus, not gram-negative pathogens.

Microbiology and initial antibiotic therapy for injection drug users and non-injection drug users with cutaneous abscesses in the era of community-associated methicillin-resistant Staphylococcus aureus.

OBJECTIVES: The incidence of cutaneous abscesses has increased markedly since the emergence of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA). Injection drug use is a risk factor for abscesses and may affect the microbiology and treatment of these infections. In a cohort of patients hospitalized with cutaneous abscesses in the era of CA-MRSA, the objectives were to compare the microbiology of abscesses between injection drug users and non-injection drug users and evaluate antibiotic therapy started in the emergency department (ED) in relation to microbiologic findings and national guideline treatment recommendations. METHODS: This was a secondary analysis of two published retrospective cohorts of patients requiring hospitalization for acute bacterial skin infections between January 1, 2007, and May 31, 2012, in seven academic and community hospitals in Colorado. In the subgroup of patients with cutaneous abscesses, microbiologic findings and the antibiotic regimens started in the ED were compared between injection drug users and non-injection drug users. Antibiotic regimens involving multiple agents, lack of activity against MRSA, or an agent with broad Gram-negative activity were classified as discordant with Infectious Diseases Society of America (IDSA) guideline treatment recommendations. RESULTS: Of 323 patients with cutaneous abscesses, 104 (32%) occurred in injection drug users. Among the 235 cases where at least one microorganism was identified by culture, S. aureus was identified less commonly among injection drug users compared with non-injection drug users (55% vs. 75%, p = 0.003), with similar patterns observed for MRSA (33% vs. 47%, p = 0.054) and methicillin-susceptible S. aureus (17% vs. 26%, p = 0.11). In contrast to S. aureus, streptococcal species (53% vs. 25%, p < 0.001) and anaerobic organisms (29% vs. 10%, p < 0.001) were identified more commonly among injection drug users. Of 88 injection drug users and 186 non-injection drug users for whom antibiotics were started in the ED, the antibiotic regimens were discordant with IDSA guideline recommendations in 47 (53%) and 101 (54%), respectively (p = 0.89). In cases where MRSA was ultimately identified, the antibiotic regimen started in the ED lacked activity against this pathogen in 14% of cases. CONCLUSIONS: Compared with non-injection drug users, cutaneous abscesses in injection drug users were less likely to involve S. aureus, including MRSA, and more likely to involve streptococci and anaerobes; however, MRSA was common in both groups. Antibiotic regimens started in the ED were discordant with national guidelines in over half of cases and often lacked activity against MRSA when this pathogen was present.

Comparison of the microbiology and antibiotic treatment among diabetic and nondiabetic patients hospitalized for cellulitis or cutaneous abscess.

BACKGROUND: Among diabetics, complicated skin infections may involve gram-negative pathogens; however, the microbiology of cellulitis and cutaneous abscess is not well established. OBJECTIVE: To compare the microbiology and prescribing patterns between diabetics and nondiabetics hospitalized for cellulitis or abscess. DESIGN: Secondary analysis of 2 published retrospective cohorts. SETTING/PATIENTS: Adults hospitalized for cellulitis or abscess, excluding infected ulcers or deep tissue infections, at 7 academic and community facilities. METHODS: Microbiological findings and antibiotic use were compared among diabetics and nondiabetics. Multivariable logistic regression was performed to identify factors associated with exposure to broad gram-negative therapy, defined as receipt of at least 2 calendar days of ß-lactamase inhibitors, second- to fifth-generation cephalosporins, fluoroquinolones, carbapenems, tigecycline, aminoglycosides, or colistin. RESULTS: Of 770 total patients with cellulitis or abscess, 167 (22%) had diabetes mellitus. Among the 38% of cases with a positive culture, an aerobic gram-positive organism was isolated in 90% of diabetics and 92% of nondiabetics (P = 0.59); aerobic gram-negative organisms were isolated in 7% and 12%, respectively (P = 0.28). Overall, diabetics were more likely than nondiabetics to be exposed to broad gram-negative therapy (54% vs 44% of cases, P = 0.02). By logistic regression, diabetes mellitus was independently associated with exposure to broad gram-negative therapy (odds ratio: 1.66, 95% confidence interval: 1.15-2.40). CONCLUSION: In cases of cellulitis or abscess associated with a positive culture, gram-negative pathogens were not more common among diabetics compared with nondiabetics. However, diabetics were overall more likely to be exposed to broad gram-negative therapy suggesting this prescribing practice may not be not warranted.

Antibiotic prescribing practices in a multicenter cohort of patients hospitalized for acute bacterial skin and skin structure infection.

OBJECTIVE: Hospitalizations for acute bacterial skin and skin structure infection (ABSSSI) are common. Optimizing antibiotic use for ABSSSIs requires an understanding of current management. The objective of this study was to evaluate antibiotic prescribing practices and factors affecting prescribing in a diverse group of hospitals. DESIGN: Multicenter, retrospective cohort study. SETTING: Seven community and academic hospitals. METHODS: Children and adults hospitalized between June 2010 and May 2012 for cellulitis, wound infection, or cutaneous abscess were eligible. The primary endpoint was a composite of 2 prescribing practices representing potentially avoidable antibiotic exposure: (1) use of antibiotics with a broad spectrum of activity against gram-negative bacteria or (2) treatment duration greater than 10 days. RESULTS: A total of 533 cases were included: 320 with nonpurulent cellulitis, 44 with wound infection or purulent cellulitis, and 169 with abscess. Of 492 cases with complete prescribing data, the primary endpoint occurred in 394 (80%) cases and varied significantly across hospitals (64%-97%; P < .001). By logistic regression, independent predictors of the primary endpoint included wound infection or purulent cellulitis (odds ratio [OR], 5.12 [95% confidence interval (CI)], 1.46-17.88), head or neck involvement (OR, 2.83 [95% CI, 1.17-6.82]), adult cases (OR, 2.20 [95% CI, 1.18-4.11]), and admission to a community hospital (OR, 1.90 [95% CI, 1.05-3.44]). CONCLUSIONS: Among patients hospitalized for ABSSSI, use of antibiotics with broad gram-negative activity or treatment courses longer than 10 days were common. There may be substantial opportunity to reduce antibiotic exposure through shorter courses of therapy targeting gram-positive bacteria.

Prophylactic antibiotics in open fractures: a pilot randomized clinical safety study.

OBJECTIVE: To develop preliminary data on Staphylococcus aureus colonization and surgical site infections (SSIs) in patients with open fractures who received standard antibiotic prophylaxis compared with a regimen including targeted methicillin-resistant Staphylococcus aureus (MRSA) coverage. DESIGN: Randomized prospective clinical trial. PATIENTS: Adult patients who presented to the emergency department with an open fracture between April 2009 and July 2011. INTERVENTIONS: One hundred thirty patients were randomized to receive prophylaxis with either cefazolin alone (control arm) or vancomycin and cefazolin (experimental arm) from presentation to the emergency department until 24 hours after the surgical intervention. Screening for S. aureus carriage was performed with nares swabs and predebridement and postdebridement open fracture wound swabs. Patients underwent prospective assessment for the development of SSI for no less than 30 days and up to 12 months. RESULTS: Nasal colonization of methicillin-sensitive S. aureus and MRSA among the sample was 20% and 3%, respectively. No significant difference in the rates of SSI was observed between the study arms (15% vs 19%, respectively, P = 0.62). Staphylococcus aureus caused 55% of the deep incisional/organ space SSI, with 18% attributed to MRSA. A significantly higher rate of MRSA SSIs was observed among MRSA carriers compared with noncarriers (33% vs 1%, respectively, P = 0.003). CONCLUSIONS: Staphylococcus aureus nasal colonization in trauma patients with open fractures is similar to that of the general community. In this pilot study, the addition of vancomycin to standard antibiotic prophylaxis was found safe, but its efficacy should be evaluated in a larger multiinstitutional trial.

Successful limb-sparing treatment strategy for diabetic foot osteomyelitis.

BACKGROUND: Diabetic foot osteomyelitis is common and causes substantial morbidity, including major amputations, yet the optimal treatment approach is unclear. We evaluated an approach to limb salvage that combines early surgical debridement or limited amputation with antimicrobial therapy. METHODS: We conducted a retrospective cohort study of patients treated between May 1, 2005, and May 31, 2007. The primary end point was cure, defined as not requiring further treatment for osteomyelitis of the affected limb. The secondary end point was limb salvage, defined as not requiring a below-the-knee amputation or a more proximal amputation. RESULTS: Fifty patients with diabetic foot osteomyelitis met the study criteria. Initial surgical management included local amputation in 43 patients (86%) and debridement without amputation in seven (14%). Most infections (n = 30; 60%) were polymicrobial, and Staphylococcus aureus was the most common pathogen (n = 23; 46%). Parenteral antibiotics were used in 45 patients (90%). Patients who had pathologic evidence of osteomyelitis at the surgical margin received therapy for a median of 43 days (interquartile range [IQR], 36-56 days), whereas those without evidence of residual osteomyelitis received therapy for a median of 19 days (IQR, 13-40 days). Overall, 32 patients (64%) were considered cured after a median follow-up of 26 months (IQR, 12-38 months). Fifteen of 18 patients (83%) who failed initial therapy were treated again with limb-sparing surgery. Limb salvage was achieved in 47 patients (94%), with only three patients (6%) requiring below-the-knee amputation. CONCLUSIONS: In patients with diabetic foot osteomyelitis, surgical debridement or limited amputation plus antimicrobial therapy is effective at achieving clinical cure and limb salvage.

The role of prophylactic antibiotics in open fractures in an era of community-acquired methicillin-resistant Staphylococcus aureus.

Infection is a feared complication and a common cause of loss of function following open fractures. Despite the evidence supporting the administration of prophylactic antibiotics after open fractures, data demonstrating the optimal regimen is lacking. We reviewed the data supporting the current prophylaxis recommendations and the changing epidemiology of Staphylococcus aureus, the most common cause of surgical site infection in patients with open fractures. Although widespread emergence of methicillin-resistant Staphylococcus aureus (MRSA) has been described in both hospital and community settings, to date, no studies have addressed the need for prophylaxis against MRSA in patients with open fractures. Until well-designed randomized trials are conducted, we recommend that providers consider selecting antibiotics active against MRSA for open fracture prophylaxis based on the local prevalence of MRSA carriage and individualized risk factors.

Ochrobactrum anthropi septic arthritis: case report and implications in orthopedic infections.

Ochrobactrum anthropi is a rare cause of orthopedic infections. We report the second case of Ochrobactrum anthropi septic arthritis in the literature. Our case highlights the ability of Ochrobactrum anthropi to cause septic arthritis and its relevance in the field of orthopedic infections.