Etiology of Cellulitis and Clinical Prediction of Streptococcal Disease: A Prospective Study

Streptococcus dysgalactiae subsp. equisimilis infection and its intersection with Streptococcus pyogenes

SUMMARYStreptococcus dysgalactiae subsp. equisimilis (SDSE) is an increasingly recognized cause of disease in humans. Disease manifestations range from non-invasive superficial skin and soft tissue infections to life-threatening streptococcal toxic shock syndrome and necrotizing fasciitis. Invasive disease is usually associated with co-morbidities, immunosuppression, and advancing age. The crude incidence of invasive disease approaches that of the closely related pathogen, Streptococcus pyogenes. Genomic epidemiology using whole-genome sequencing has revealed important insights into global SDSE population dynamics including emerging lineages and spread of anti-microbial resistance. It has also complemented observations of overlapping pathobiology between SDSE and S. pyogenes, including shared virulence factors and mobile gene content, potentially underlying shared pathogen phenotypes. This review provides an overview of the clinical and genomic epidemiology, disease manifestations, treatment, and virulence determinants of human infections with SDSE with a particular focus on its overlap with S. pyogenes. In doing so, we highlight the importance of understanding the overlap of SDSE and S. pyogenes to inform surveillance and disease control strategies.

Serological Responses to Streptococcus pyogenes Vaccine Candidate Antigens Suggests That Streptococcus dysgalactiae Is the Predominant Cause of Lower Limb Cellulitis

Background

A future Streptococcus pyogenes (Strep A) vaccine will ideally prevent a significant burden of lower limb cellulitis; however, natural immune responses to proposed vaccine antigens following an episode of cellulitis remain uncharacterized.

Methods

We enrolled 63 patients with cellulitis and 26 with invasive beta hemolytic streptococci infection, using a multiplexed assay to measure immunoglobulin G against Strep A vaccine candidate antigens, including: streptolysin O (SLO), deoxyribonuclease B (DNB), group A carbohydrate (GAC), C5a peptidase (ScpA), cell envelope proteinase (SpyCEP), and adhesion and division protein (SpyAD). Responses in the invasive cohort were used to predict the infecting etiology in the cellulitis cohort.

Results

Of 41 patients with cellulitis and paired serological samples, 68.3% had evidence of beta hemolytic streptococci infection by conventional anti-SLO and/or anti-DNB criteria. A positive serological response to at least 1 of the tested antigens was seen in 78.0% of the cellulitis cohort. Individually, anti-SLO (58.5%), anti-SpyAD (46.3%), and anti-ScpA (39.0%) were the most common. Based on principal component analysis, increases in these 3 antibodies, without responses to DNB, GAC, and SpyCEP characterized Streptococcus dysgalactiae subspecies equisimilis (SDSE) infection.

Conclusions

SDSE appears to be the predominant cause of lower limb cellulitis. Effective Strep A vaccines incorporating antigens that provide additional cross protection against SDSE may prevent a significant burden of lower limb cellulitis.

Genomic epidemiology of Streptococcus dysgalactiae subsp. equisimilis strains causing invasive disease in Norway during 2018

Background

Streptococcus dysgalactiae subspecies equisimilis (SDSE) is an emerging global pathogen, yet the epidemiology and population genetics of SDSE species have not been extensively characterized.

Methods

We carried out whole genome sequencing to characterize 274 SDSE isolates causing bloodstream infections obtained through national surveillance program in 2018. We conducted multilocus sequence typing (MLST), emm-typing, core genome phylogeny, as well as investigated key features associated with virulence. Moreover, comparison to SDSE from other geographic regions were performed in order to gain more insight in the evolutionary dynamics in SDSE.

Results

The phylogenetic analysis indicated a substantial diversity of emm-types and sequence types (STs). Briefly, 17 emm-types and 58 STs were identified that formed 10 clonal complexes (CCs). The predominant ST-types were ST20 (20%), ST17 (17%), and ST29 (11%). While CC17 and CC29 clades showed a substantial heterogeneity with well-separated emm-associated subclades, the CC20 clade harboring the stG62647 emm-type was more homogenous and the most prevalent in the present study. Moreover, we observed notable differences in the distribution of clades within Norway, as well as several disseminated CCs and also distinct geographic variations when compared to data from other countries. We also revealed extensive intra-species recombination events involving surface exposed virulence factors, including the emm gene important for phylogenetic profiling.

Conclusion

Recombination events involving the emm as well as other virulence genes in SDSE, are important mechanisms in shaping the genetic variability in the SDSE population, potentially offering selective advantages to certain lineages. The enhanced phylogenetic resolution offered by whole genome sequencing is necessary to identify and delimitate outbreaks, monitor and properly characterize emerging strains, as well as elucidate bacterial population dynamics.

Clinical Impact of Staphylococcus aureus Skin and Soft Tissue Infections

The pathogenic bacterium Staphylococcus aureus is the most common pathogen isolated in skin-and-soft-tissue infections (SSTIs) in the United States. Most S. aureus SSTIs are caused by the epidemic clone USA300 in the USA. These infections can be serious; in 2019, SSTIs with S. aureus were associated with an all-cause, age-standardized mortality rate of 0.5 globally. Clinical presentations of S. aureus SSTIs vary from superficial infections with local symptoms to monomicrobial necrotizing fasciitis, which can cause systemic manifestations and may lead to serious complications or death. In order to cause skin infections, S. aureus employs a host of virulence factors including cytolytic proteins, superantigenic factors, cell wall-anchored proteins, and molecules used for immune evasion. The immune response to S. aureus SSTIs involves initial responders such as keratinocytes and neutrophils, which are supported by dendritic cells and T-lymphocytes later during infection. Treatment for S. aureus SSTIs is usually oral therapy, with parenteral therapy reserved for severe presentations; it ranges from cephalosporins and penicillin agents such as oxacillin, which is generally used for methicillin-sensitive S. aureus (MSSA), to vancomycin for methicillin-resistant S. aureus (MRSA). Treatment challenges include adverse effects, risk for Clostridioides difficile infection, and potential for antibiotic resistance.

The effects of air pollutants exposure on the transmission and severity of invasive infection caused by an opportunistic pathogen Streptococcus pyogenes

Currently, urbanization is associated with an increase in air pollutants that contribute to invasive pathogen infections by altering the host's innate immunity and antimicrobial resistance capability. Streptococcus pyogenes, also known as Group A Streptococcus (GAS), is a gram-positive opportunistic pathogen that causes a wide range of diseases, especially in children and immunosuppressed individuals. Diesel exhaust particle (DEP), a significant constituent of particulate matter (PM), are considered a prominent risk factor for respiratory illness and circulatory diseases worldwide. Several clinical and epidemiological studies have identified a close association between PM and the prevalence of viral and bacterial infections. This study investigated the role of DEP exposure in increasing pulmonary and blood bacterial counts and mortality during GAS M1 strain infection in mice. Thus, we characterized the upregulation of reactive oxygen species production and disruption of tight junctions in the A549 lung epithelial cell line due to DEP exposure, leading to the upregulation of GAS adhesion and invasion. Furthermore, DEP exposure altered the leukocyte components of infiltrated cells in bronchoalveolar lavage fluid, as determined by Diff-Quik staining. The results highlighted the DEP-related macrophage dysfunction, neutrophil impairment, and imbalance in pro-inflammatory cytokine production via the toll-like receptor 4/mitogen-activated protein kinase signaling axis. Notably, the tolerance of the GAS biofilms toward potent antibiotics and bacterial resistance against environmental stresses was also significantly enhanced by DEP. This study aimed to provide a better understanding of the physiological and molecular interactions between exposure to invasive air pollutants and susceptibility to invasive GAS infections.

Etiology, clinical features, management, and outcomes of skin and soft tissue infections in hospitalized children: A 10-year review

PURPOSE

This study aimed to describe the etiology, clinical features, hospital course, and outcomes of hospitalized children with skin and soft tissue infections (SSTIs) and to test if clinical and laboratory variables at admission could differentiate between community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) and community-acquired methicillin-sensitive S. aureus (CA-MSSA).

METHODS

We reviewed the clinical, laboratory, treatment, and outcome data for children hospitalized with SSTIs, aged 0-18 years at MacKay Children's Hospital between 2010 and 2019. Multivariable logistic regression was used to identify independent predictors of CA-MRSA and CA-MSSA SSTIs.

RESULTS

A total of 1631 patients were enrolled. Erysipelas/cellulitis (73.8%) was the most common pediatric SSTI type, followed by acute lymphadenitis (13.6%) and abscess/furuncle/carbuncle (8.6%). Among the 639 culture-positive isolates (purulent SSTIs), 142 (22.2%) were CA-MSSA and 363 (56.8%) were CA-MRSA. The age group 0-1 month (OR, 6.52; 95% CI 1.09-38.92; P = 0.04) and local lymph node reaction (OR, 2.47; 95% CI 1.004-6.08; P = 0.049) were independent factors for differentiating children with CA-MSSA from those with CA-MRSA SSTIs. MRSA isolates in our cohort were highly susceptible to glycopeptides (100%), linezolid (100%), daptomycin (100%), and sulfamethoxazole/trimethoprim (98.6%) but were significantly less susceptible to clindamycin compared with MSSA (34.2% vs. 78.2%, P < 0.001).

CONCLUSION

S. aureus is the leading pathogen of culture-proven SSTIs in hospitalized children with MRSA accounting for more than half. Determining the optimal empirical antibiotics in CA-SSTIs may rely on the patient's age, disease severity, and local epidemiologic data.

Outpatient management of moderate cellulitis in children using high-dose oral cephalexin

Objectives

To evaluate the effectiveness of a high-dose (HD) oral cephalexin treatment guideline for children with moderate cellulitis treated as outpatients.

Methods

In this retrospective cohort study, we included children who presented to the emergency department (ED) with moderate cellulitis and treated according to the institution’s HD oral cephalexin guideline over a 2-year period. All children had standardized follow-up at a medical day hospital (MDH). Treatment was considered effective in the absence of treatment failure, defined as admission, switch to IV treatment or ED visit within 2 weeks of discharge from the MDH. Safety was ascertained by recording adverse events and severe complications at follow-up.

Results

A total of 123 children were treated as outlined in the guideline, including 117 treated with HD oral cephalexin. The success rate was 89.7% (105/117). Among 12 (10.3%) children who had treatment failure, 10 (8.5%) required admission, 1 (0.9%) received IV antibiotics at the MDH and 1 (0.9%) had a return visit to the ED without admission. No severe complications were reported; four abscesses required drainage and one patient had a rash. The mean number of visits per child at the MDH was 1.6 (SD 1.0).

Conclusions

With a success rate of 89.7%, HD oral cephalexin seems effective and safe for the treatment of children with moderate cellulitis. Its use potentially reduces hospitalization rates for this condition and decreases the need for IV insertion.

Cellulitis: A Review of Current Practice Guidelines and Differentiation from Pseudocellulitis

Cellulitis, an infection involving the deep dermis and subcutaneous tissue, is the most common reason for skin-related hospitalization and is seen by clinicians across various disciplines in the inpatient, outpatient, and emergency room settings, but it can present as a diagnostic and therapeutic challenge. Cellulitis is a clinical diagnosis based on the history of present illness and physical examination and lacks a gold standard for diagnosis. Clinical presentation with acute onset of redness, warmth, swelling, and tenderness and pain is typical. However, cellulitis can be difficult to diagnose due to a number of infectious and non-infectious clinical mimickers such as venous stasis dermatitis, contact dermatitis, eczema, lymphedema, and erythema migrans. Microbiological diagnosis is often unobtainable due to poor sensitivity of culture specimens. The majority of non-purulent, uncomplicated cases of cellulitis are caused by β-hemolytic streptococci or methicillin-sensitive Staphylococcus aureus, and appropriate targeted coverage of this pathogen with oral antibiotics such as penicillin, amoxicillin, and cephalexin is sufficient. Even with rising rates of community-acquired methicillin-resistant Staphylococcus aureus, coverage for non-purulent cellulitis is generally not recommended.

Treatment of Recurrent Severe Cellulitis with a Pill in Pocket Approach

Cellulitis is a common condition that plagues healthcare systems and is associated with significant healthcare costs and resource allocations. With ample antimicrobial therapy this infectious syndrome can be easily treated but recurrence is common. Many conditions predispose patients to be at risk for recurrent cellulitis with chronic lymphoedema being a significant risk factor secondary to pooling of lymphatic fluid and impaired local immune responses. Moreover, patients with chronic lymphoedema can be at risk for acute onset of severe cellulitis requiring urgent medical evaluation and treatment. Consequently, to prevent recurrent cellulitis episodes, the use of long-term oral antibiotics has been advocated, but when recurrences occur despite long-term antibiotic use limited options are available. In this case report, a unique treatment approach for preventing severe cellulitis is discussed with a pill in the pocket approach with the use of oral tedizolid. This has thwarted the need for recurrent hospitalizations and reduced health care costs for this individual patient. Herein this treatment approach is discussed as is the rationale for using tedizolid instead of other antibiotics.

Differentiating Upper Extremity Necrotizing Soft Tissue Infection From Serious Cellulitis and Abscess

Introduction

Necrotizing soft tissue infection (NSTI) of the upper extremity (UE) is a rapidly progressing infection that requires early diagnosis and emergent treatment to decrease risks of loss of limb or life. Clinical presentation, particularly of early NSTI, can appear similar to serious cellulitis or abscess. The purpose of this study was to identify factors that are associated with NSTI rather than serious cellulitis and abscess to differentiate patients with similar clinical presentations.

Methods

This study uses a retrospective cohort design that compares patients ultimately diagnosed with UE NSTI versus those diagnosed with UE serious cellulitis or abscess. Cohorts were matched using the Laboratory Risk Indicators for Necrotizing Fasciitis (LRINEC) score in the setting of UE soft tissue infection. Laboratory values, vital signs, subjective symptoms, and social factors including substance abuse and domiciled status were recorded. Continuous variables were compared using the Mann-Whitney U test, whereas categorical variables were compared using the chi-squared test or the Fisher exact test (for expected values less than 5). A binary logistic regression for continuous and categorical variables was also performed. Significance was set at p<0.05. Univariate and multivariate analyses were performed.

Results

Multivariate statistical analysis and clinical interpretation of data identified four factors more associated with a diagnosis of NSTI than serious cellulitis or abscess: elevated lactate on hospital presentation, a patient-reported history of fever, male gender, and homelessness. 

Conclusions

In patients with upper extremity infections, the clinical presentation of NSTI and serious cellulitis or abscess may appear similar. In this retrospective cohort of patients matched with LRINEC scores, elevated lactate, subjective fever, male gender, and homelessness were significantly associated with NSTI rather than serious cellulitis or abscess. 

Diagnosis and Management of Cellulitis and Abscess in the Emergency Department Setting: An Evidence-Based Review

BACKGROUND

Cellulitis and abscess are a common reason for presentation to the emergency department, although there are several nuances to the care of these patients.

OBJECTIVE

The purpose of this narrative review article was to provide a summary of the background, pathophysiology, diagnosis, and management of cellulitis and abscesses with a focus on emergency clinicians.

DISCUSSION

The most common bacteria causing cellulitis are Staphylococcus aureus, Streptococcus pyogenes, and other β-hemolytic streptococci, and methicillin-resistant S. aureus is most common in abscesses. The history and physical examination are helpful in differentiating cellulitis and abscess in many cases, and point-of-care ultrasound can be a useful tool in unclear cases. Treatment for cellulitis typically involves a penicillin or cephalosporin, and treatment of abscesses is incision and drainage. Loop drainage is preferred over the traditional incision and drainage technique, and adjunctive antibiotics can be considered. Most patients can be managed as outpatient.

CONCLUSIONS

It is essential for emergency physicians to be aware of the current evidence regarding the diagnosis and management of patients with cellulitis and abscess.

Differentiating Lower Extremity Necrotizing Soft Tissue Infection from Severe Cellulitis by Laboratory Parameters and Relevant History Points

Background

Necrotizing soft tissue infection (NSTI) of the lower extremity (LE) is a rapidly progressing infection that requires early diagnosis and prompt treatment to decrease risks of loss of limb or life. Clinical presentation, particularly of early NSTI, can appear similar to severe cellulitis. The purpose of this study is to identify factors that are associated with NSTI rather than severe cellulitis to differentiate patients with similar clinical presentation.

Methods

This retrospective cohort design study compares patients finally diagnosed with LE NSTI versus those diagnosed with severe cellulitis. Cohorts were matched using the modified Laboratory Risk Indicator for Necrotizing Fasciitis (m-LRINEC) score in the setting of LE soft tissue infection. Laboratory values, vital signs, subjective symptoms, and social factors including substance abuse were recorded. Univariate and multivariate analyses were performed.

Results

Multivariate statistical analysis and clinical interpretation of data identified four factors more associated with a diagnosis of NSTI than severe cellulitis: elevated lactate, a patient-reported history of fever, male gender, and intravenous substance user.

Conclusion

In patients with lower extremity infections, the clinical presentation of NSTI and severe cellulitis may appear similar. In this retrospective cohort of patients matched with m-LRINEC scores, elevated lactate, subjective fever, male gender, and intravenous substance abuser were significantly associated with NSTI rather than severe cellulitis. Further studies of these factors in the clinical setting can help tailor the differential diagnosis in the care of patients with severe lower extremity infections. Matched with m-LRINEC scores, elevated lactate, subjective fever, male gender, and intravenous substance abuser were significantly associated with NSTI rather than severe cellulitis. Further studies of these factors in the clinical setting can help tailor the differential diagnosis in the care of patients with severe lower extremity infections.

Clinical and immunologic differences in cellulitis vs. pseudocellulitis

Introduction: The immunologic mechanisms between cellulitis and pseudocellulitis differ greatly, even though their clinical presentations may overlap.Areas covered: This article discusses cellulitis and common entities within the pseudocellulitis spectrum including acute lymphedema, superficial venous thrombosis, allergic contact dermatitis, lipodermatosclerosis, stasis dermatitis, erythema nodosum, cutaneous gout, and bursitis. The literature search was conducted from PubMed search engine between March and May 2021.Expert commentary: While immunologic differences in cellulitis and the various entities of pseudocellulitis are clear, there is a practice gap in applying these differences to the clinic and hospital setting. Further, existing studies are weakened by the lack of a gold-standard diagnosis in this disease category. Additional work is necessary in developing a gold-standard for the diagnosis and secondly, to project these immunologic differences as biomarkers to differentiate sterile inflammation from a potential life threatening bacterial or fungal infection.

[Indications for and Limits of conservative Treatment in Hand Infections]

The treatment of infections of the hand is an important part in hand surgery. Despite oft new antibiotic therapy there is a major part of surgical intervention. But there are certain cases in which a conservative treatment is indicated if a closed control is provided. Important is a careful examination, a detailed anamnesis of profession, hobby, animal or human contact, journey and secondary disease. Apart from antibiotics, limited immobilisation, physical conservation, moist dressing and pain management are important factors. In case of a conservative therapy, attention must be payed to the kind of infection and secondary diseases because there is a higher risk for complications, combined Infections and atypical pathogens in immunosuppressed patients. Typical indications for conservative treatment are erysipelas, cellulitis, early stages of felon and paronychia. Rare indications are infections with Erysipelothrix rhusiopathiae, Herpes simplex and fungal pathogens. No indications are symptoms longer than 2 days, abscess, bacterial infections of tendons, necrotizing fasciitis and empyema.

Risk Factors and Predictors of Mortality in Streptococcal Necrotizing Soft-tissue Infections: A Multicenter Prospective Study

BACKGROUND

Necrotizing soft-tissue infections (NSTI) are life-threatening conditions often caused by β-hemolytic streptococci, group A Streptococcus (GAS) in particular. Optimal treatment is contentious. The INFECT cohort includes the largest set of prospectively enrolled streptococcal NSTI cases to date.

METHODS

From the INFECT cohort of 409 adults admitted with NSTI to 5 clinical centers in Scandinavia, patients culture-positive for GAS or Streptococcus dysgalactiae (SD) were selected. Risk factors were identified by comparison with a cohort of nonnecrotizing streptococcal cellulitis. The impact of baseline factors and treatment on 90-day mortality was explored using Lasso regression. Whole-genome sequencing of bacterial isolates was used for emm typing and virulence gene profiling.

RESULTS

The 126 GAS NSTI cases and 27 cases caused by SD constituted 31% and 7% of the whole NSTI cohort, respectively. When comparing to nonnecrotizing streptococcal cellulitis, streptococcal NSTI was associated to blunt trauma, absence of preexisting skin lesions, and a lower body mass index. Septic shock was significantly more frequent in GAS (65%) compared to SD (41%) and polymicrobial, nonstreptococcal NSTI (46%). Age, male sex, septic shock, and no administration of intravenous immunoglobulin (IVIG) were among factors associated with 90-day mortality. Predominant emm types were emm1, emm3, and emm28 in GAS and stG62647 in SD.

CONCLUSIONS

Streptococcal NSTI was associated with several risk factors, including blunt trauma. Septic shock was more frequent in NSTI caused by GAS than in cases due to SD. Factors associated with mortality in GAS NSTI included age, septic shock, and no administration of IVIG.

Cellulitis

Cellulitis is a common infection of the skin and subcutaneous tissue caused predominantly by gram-positive organisms. Risk factors include prior episodes of cellulitis, cutaneous lesions, tinea pedis, and chronic edema. Cellulitis is a clinical diagnosis and presents with localized skin erythema, edema, warmth, and tenderness. Uncomplicated cellulitis can be managed in the outpatient setting with oral antibiotics. Imaging often is not required but can be helpful. Recurrent cellulitis is common and predisposing conditions should be assessed for and treated at the time of initial diagnosis. For patients with frequent recurrences despite management of underlying conditions, antimicrobial prophylaxis can be effective.

Diagnostic value of laboratory parameters for the discrimination between erysipelas and limited cellulitis

BACKGROUND AND OBJECTIVES

Erysipelas, caused by beta-hemolytic streptococci, and limited cellulitis, frequently caused by Staphylococcus aureus or other bacteria, are skin and soft tissue infections characterized by typical clinical signs. However, despite the therapeutical relevance they are often not differentiated (e.g in clinical trials). Erysipelas are efficiently treated with penicillin, while limited cellulitis is treated with more wide-spectrum antibiotics. This study investigates whether parameters such as CRP, blood counts or novel parameters like immature granulocytes could serve as biomarkers to distinguish between these entities.

PATIENTS AND METHODS

For this retrospective analysis 163 patients were included. We compared laboratory markers in patients with erysipelas (n = 68) to those with limited cellulitis (n = 41) of the leg. Both erysipelas and limited cellulitis were defined clinically, with an additional aspect for erysipelas being a prompt response to penicillin.

RESULTS

Erysipelas were characterized by higher levels of inflammation. CRP and leukocyte counts are the best parameters to discriminate between both infections. A CRP value ≥ 3.27 mg/dl indicated the diagnosis of erysipelas with 75 % sensitivity and 73.2 % specificity.

CONCLUSIONS

Our results support the thesis that erysipelas and limited cellulitis are distinct infections as defined in the German guidelines and that an assessment of CRP and leukocytes is useful for differential diagnosis.

Route and duration of antibiotic therapy in acute cellulitis: A systematic review and meta-analysis of the effectiveness and harms of antibiotic treatment

OBJECTIVES

Compared with guideline recommendations, antibiotic overuse is common in treating cellulitis. We conducted a systematic review and meta-analyses on antibiotic route and duration of treatment for cellulitis in adults and children.

METHODS

We searched MEDLINE, EMBASE and trial registries from inception to Dec 11, 2019 for interventional and observational studies of antibiotic treatment for cellulitis. Exclusions included case series/reports, pre-septal/orbital cellulitis and non-English language articles. Random-effects meta-analyses were used to produce summary relative risk (RR) estimates for our primary outcome of clinical response.

PROSPERO

CRD42018100602.

RESULTS

We included 47/8423 articles, incorporating data from eleven trials (1855 patients) in two meta-analyses. The overall risk of bias was moderate. Only two trials compared the same antibiotic agent in each group. We found no evidence of difference in clinical response rates for antibiotic route or duration (RR(oral:IV)=1.12, 95%CI 0.98-1.27, I²=32% and RR(shorter:longer)=0.99, 95%CI 0•96-1.03, I² = 0%, respectively). Findings were consistent in observational studies. Follow-up data beyond 30 days were sparse.

CONCLUSIONS

The evidence base for antibiotic treatment decisions in cellulitis is flawed by biased comparisons, short follow-up and lack of data around harms of antibiotic overuse. Future research should focus on developing patient-tailored antibiotic prescribing for cellulitis to reduce unnecessary antibiotic use.

Clinical predictors and impact of bacteremia in cirrhotic patients with acute skin and skin structure infection

OBJECTIVE

Acute bacterial skin and skin structure infection (ABSSSI) is a common cause of acute admissions in patients with cirrhosis worldwide, but the disease is not well-understood epidemiologically with respect to factors that determine positive blood cultures or patient mortality. The aim of this study was to understand the utility of blood cultures and the association between bacteremia and mortality in cirrhotic patients with ABSSSI. We conducted a retrospective study to investigate factors associated with positive blood cultures and mortality in cirrhotic patients with ABSSSI.

METHODS

A retrospective cohort study of hospitalized adult cirrhotic patients with ABSSSI was conducted in a tertiary hospital in Taiwan between March 2015 and December 2016.

RESULTS

A total of 122 hospitalized cirrhotic patients with ABSSSI were included. The overall mortality rate was 9% (11/122), and 23 patients had positive blood culture results. Comorbidities that were significant risk factors for a positive blood culture included diabetes mellitus, acute kidney injury (AKI), and acute-on-chronic liver failure (ACLF). Significant risk factors evident in laboratory evaluations included higher model for end-stage liver disease (MELD) score, higher serum lactate, and lower serum albumin level. Bacteremia was also a significant factor associated with mortality.

CONCLUSION

A blood culture should be considered for cirrhotic patients with ABSSSI with diabetes mellitus, AKI, ACLF or those exhibiting abnormal albumin, lactate levels, or high MELD score because of the positive correlation between bacteremia and mortality.

Association of the Dundee severity classification with mortality, length of stay and readmission in adult inpatients with cellulitis

Background

The Dundee classification is a simple severity assessment tool that could optimize treatment decisions and clinical outcomes in adult patients with cellulitis; however, it has not been validated in a large cohort.

Objectives

To determine whether the Dundee classification reliably identified those patients with cellulitis who had a higher mortality, a longer length of hospital stay or an increased risk of readmission.

Methods

We performed a retrospective study of all adults with a primary discharge diagnosis of cellulitis admitted to Auckland City Hospital from August 2013 to June 2015. We classified patients by severity using the Dundee scoring system.

Results

The 30 day all-cause mortality in adult patients with a discharge diagnosis of cellulitis was 2% (29/1462) overall, and was 1% (10/806), 2% (6/271), 3% (10/353) and 9% (3/32) in Classes 1, 2, 3 and 4 of the Dundee classification, respectively (P = 0.01). Mortality was strongly associated with age >65 years (OR 9.37, 95% CI 3.00-41.23) and with heart failure (OR 6.16, 95% CI 2.73-14.23). There were significant associations between the Dundee classification and the incidence of bacteraemia, the length of hospital stay and the rate of readmission to hospital.

Conclusions

The Dundee classification is a simple, reliable tool that can be easily applied in clinical settings to predict risk of mortality in order to determine which patients can be managed in the community with oral or intravenous therapy, and which require inpatient care.

Is coverage of S. aureus necessary in cellulitis/erysipelas? A literature review

BACKGROUND

Empirical treatment of patients with cellulitis/erysipelas usually targets both streptococci and methicillin-sensitive S. aureus (MSSA). However, the recommendation to empirically cover MSSA is weak and based on low-quality evidence.

METHODS AND OBJECTIVE

A systematic review was conducted in PubMed and clinical trial registries to assess the role of S. aureus in cellulitis/erysipelas and the need for empirical MSSA coverage.

RESULTS

Combined microbiological and serological data, and response to penicillin monotherapy suggest that streptococci are responsible for the vast majority of cases of cellulitis/erysipelas. However, most cases are non-culturable and the specificity of microbiological and serological studies is questionable based on recent studies using molecular techniques. According to epidemiological data and three randomized controlled trials, empirical coverage of methicillin-resistant S. aureus (MRSA) is not recommended for most patients, despite the high prevalence of MRSA in many areas. If MRSA is indeed not an important cause of uncomplicated cellulitis/erysipelas, then the same may apply to MSSA. Based on indirect comparison of data from clinical studies, cure rates with penicillin monotherapy (to which most MSSA are resistant) are comparable to the cure rates reported in many studies using wider-spectrum antibiotics.

CONCLUSION

Considering the limitations of microbiological studies in identifying the pathogens responsible for cellulitis/erysipelas, treatment needs to be guided by clinical trials. Trials comparing penicillin or amoxicillin monotherapy to MSSA-covering regimens are needed to definitively answer whether empirical coverage of MSSA is needed and to identify the subset of patients that can be safely treated with penicillin or amoxicillin monotherapy.

Oral amoxicillin and amoxicillin-clavulanic acid: properties, indications and usage

BACKGROUND

Amoxicillin has been in use since the 1970s; it is the most widely used penicillin both alone and in combination with the β-lactamase clavulanic acid.

OBJECTIVES

In this narrative review, we re-examine the properties of oral amoxicillin and clavulanic acid and provide guidance on their use, with emphasis on the preferred use of amoxicillin alone.

SOURCES

Published medical literature (MEDLINE database via Pubmed).

CONTENT

While amoxicillin and clavulanic acid have similar half-lives, clavulanic acid is more protein bound and even less heat stable than amoxicillin, with primarily hepatic metabolism. It is also more strongly associated with gastrointestinal side effects, including Clostridium difficile infection, and, thus, in oral combination formulations, limits the maximum daily dose of amoxicillin that can be given. The first ratio for an amoxicillin-clavulanic acid combination was set at 4:1 due to clavulanic acid's high affinity for β-lactamases; ratios of 2:1, 7:1, 14:1 and 16:1 are currently available in various regions. Comparative effectiveness data for the different ratios are scarce. Amoxicillin-clavulanic acid is often used as empiric therapy for many of the World Health Organization's Priority Infectious Syndromes in adults and children, leading to extensive consumption, when some of these syndromes could be handled with a delayed antibiotic prescription approach or amoxicillin alone.

IMPLICATIONS

Using available epidemiological and pharmacokinetic data, we provide guidance on indications for amoxicillin versus amoxicillin-clavulanic acid and on optimal oral administration, including choice of combination ratio. More data are needed, particularly on heat stability, pharmacodynamic effects and emergence of resistance in 'real-world' clinical settings.

Antibiotic treatment for 6 days versus 12 days in patients with severe cellulitis: a multicentre randomized, double-blind, placebo-controlled, non-inferiority trial

OBJECTIVES

To investigate whether antibiotic treatment of 6 days' duration is non-inferior to treatment for 12 days in patients hospitalized for cellulitis.

METHODS

This multicentre, randomized, double-blind, placebo-controlled, non-inferiority trial enrolled adult patients hospitalized for severe cellulitis who were treated with intravenous flucloxacillin. At day 6 participants with symptom improvement who were afebrile were randomized between an additional 6 days of oral flucloxacillin or placebo in a 1:1 ratio, stratified for diabetes and hospital. The primary outcome was cure by day 14, without relapse by day 28. Secondary outcomes included a modified cure assessment and relapse rate by day 90.

RESULTS

Between August 2014 and June 2017, 151 of 248 included participants were randomized. The intention-to-treat population consisted of 76 and 73 participants allocated to 12 and 6 days of antibiotic therapy, respectively (mean age 62 years, 67% males, 24% diabetics); 38/76 (50.0%) and 36/73 (49.3%) were cured in the 12- and 6-day groups respectively (ARR 0.7 percentage points, 95%CI: -15.0 to 16.3). Cure rates were 56/76 (73.7%) and 49/73 (67.1%) with the modified cure assessment (ARR 6.6, 95%CI: -8.0 to 20.8). After initial cure without relapse, day 90 relapse rates were higher in the 6-day group (6% versus 24%, p < 0.05).

CONCLUSIONS

Given the wide confidence intervals, we can neither confirm nor refute our hypothesis that 6 days of therapy is non-inferior to 12 days of therapy. However, a 6-day course resulted in significantly more frequent relapses by day 90. These findings require confirmation in future studies.

Colonization of β-hemolytic streptococci in patients with erysipelas-a prospective study

Erysipelas is a common skin infection causing significant morbidity. At present there are no established procedures for bacteriological sampling. Here we investigate the possibility of using cultures for diagnostic purposes by determining the perianal colonization with beta-hemolytic streptococci (BHS) in patients with erysipelas. Patients with erysipelas and a control group of patients with fever without signs of skin infection were prospectively included and cultures for BHS were taken from the tonsils, the perianal area, and wounds. BHS were grouped according to Lancefield antigen, species-determined, and emm-typed. Renewed cultures were taken after four weeks from patients with erysipelas and a positive culture for BHS. 25 patients with erysipelas and 25 with fever were included. In the group with erysipelas, 11 patients (44%) were colonized with BHS, ten patients were colonized in the perianal area, and one patient in the throat. In contrast, only one patient in the control group was colonized (p = 0.005 for difference). All of the patients with erysipelas colonized with BHS had an erythema located to the lower limb. The BHS were then subjected to MALDI-TOF MS and most commonly found to be Streptococcus dysgalactiae. Renewed cultures were taken from nine of the 11 patients with BHS and three of these were still colonized. Streptococcus dysgalactiae colonizes the perianal area in a substantial proportion of patients with erysipelas. The possibility of using cultures from this area as a diagnostic method in patients with erysipelas seems promising.

Staphylococcus aureus colonization and acquisition of skin and soft tissue infection among Royal Marines recruits: a prospective cohort study

OBJECTIVES

Skin and soft tissue infections (SSTIs) are a serious health issue for military personnel. Of particular importance are those caused by methicillin-resistant Staphylococcus aureus and Panton-Valentine leucocidin (PVL)-positive S. aureus (PVL-SA), as they have been associated with outbreaks of SSTIs. A prospective observational study was conducted in Royal Marine (RM) recruits to investigate the prevalence of PVL-SA carriage and any association with SSTIs.

METHODS

A total of 1012 RM recruits were followed through a 32-week training programme, with nose and throat swabs obtained at weeks 1, 6, 15 and 32. S. aureus isolates were characterized by antibiotic susceptibility testing, spa typing, presence of mecA/C and PVL genes. Retrospective review of the clinical notes for SSTI acquisition was conducted.

RESULTS

S. aureus colonization decreased from Week 1 to Week 32 (41% to 26%, p < 0.0001). Of 1168 S. aureus isolates, three out of 1168 (0.3%) were MRSA and ten out of 1168 (0.9%) PVL-positive (all MSSA) and 169 out of 1168 (14.5%) were resistant to clindamycin. Isolates showed genetic diversity with 238 different spa types associated with 25 multi-locus sequence type (MLST) clonal complexes. SSTIs were seen in 35% (351/989) of recruits with 3 training days lost per recruit. SSTI acquisition rate was reduced amongst persistent carriers (p < 0.0283).

CONCLUSIONS

Nose and throat carriage of MRSA and PVL-SA was low among recruits, despite a high incidence of SSTIs being reported, particularly cellulitis. Carriage strains were predominantly MSSA with a marked diversity of genotypes. Persistent nose and/or throat carriage was not associated with SSTI acquisition. Putative person-to-person transmission within troops was identified based on spa typing requiring further research to confirm and explore potential transmission routes.

Frequent colonization of betahaemolytic streptococci at various body sites including the perineum and anal canal during erysipelas and cellulitis

Background: Erysipelas and cellulitis are usually caused by betahaemolytic streptococci but the aetiology is often difficult to verify in clinical practice. Methods: Patients with erysipelas or cellulitis were analysed for betahaemolytic streptococci in samples from multiple body sites, including the perineum and the anal canal, during the acute episode and at follow up. Healthy control persons were sampled from the same sites. Results: Betahaemolytic streptococci group A, C or G were identified in 23/28 (82%) patients, most commonly group G. A wound or ulcer, present in 16/28 (57%), was colonized in 8/16 (50%). The perineum and anal canal were colonized in 11/28 (39%) and 10/28 (36%), respectively. At follow-up after about 4 weeks, only 4/28 (14%) were colonized (p<.001). In 39 healthy control persons, no betahaemolytic streptococci group A were found, groups C or G were found in 4/39 (10%). Group B streptococci were more often identified in controls, than in patients,12/39 (31%). Conclusions: Acute episodes of erysipelas or cellulitis are associated with colonization of betahaemolytic streptococci at multiple sites including the perineum and anal canal, in particular serogroup G. This may be important for choice of primary antibiotic therapy and possibilities for prevention of relapses.

Infections Caused by Group C and G Streptococcus (Streptococcus dysgalactiae subsp. equisimilis and Others): Epidemiological and Clinical Aspects

Streptococci carrying serogroup C and G antigens, and in particular, Streptococcus dysgalactiae subsp. equisimilis (SDSE), are emerging human pathogens that are increasingly isolated from patients with a myriad of infections that range from mundane to life-threatening. SDSE is microbiologically similar to Streptococcus pyogenes. These streptococci frequently cause infections of the throat and skin and soft tissues. Moreover, they may invade the bloodstream and disseminate widely to many deep tissue sites, including the endocardium. Life-threatening invasive infections due to SDSE, including the streptococcal toxic shock syndrome, occur most frequently in patients with severe underlying medical diseases. Treatment with penicillin is adequate under most circumstances, but treatment failure occurs. SDSE may also be resistant to other antibiotic classes including tetracyclines, macrolides, and clindamycin. Most human infections caused by groups C and G streptococci are transmitted from person to person, but infections due to Streptococcus equi subsp. zooepidemicus (and, rarely, to S. equi subsp. equi) are zoonoses. Transmission of these latter species occurs by animal contact or by contamination of food products and has been associated with the development of poststreptococcal glomerulonephritis. Members of the Streptococcus anginosus group, usually classified with the viridans group of streptococci, are associated with a variety of pyogenic infections.

Pathogenicity Factors in Group C and G Streptococci

Initially recognized zoonoses, streptococci belonging to Lancefield group C (GCS) and G (GGS) were subsequently recognised as human pathogens causing a diverse range of symptoms, from asymptomatic carriage to life threatening diseases. Their taxonomy has changed during the last decade. Asymptomatic carriage is <4% amongst the human population and invasive infections are often in association with chronic diseases such as diabetes, cardiovascular diseases or chronic skin infections. Other clinical manifestations include acute pharyngitis, pneumonia, endocarditis, bacteraemia and toxic-shock syndrome. Post streptococcal sequalae such as rheumatic fever and acute glomerulonephritis have also been described but mainly in developed countries and amongst specific populations. Putative virulence determinants for these organisms include adhesins, toxins, and other factors that are essential for dissemination in human tissues and for interference with the host immune responses. High nucleotide similarities among virulence genes and their association with mobile genetic elements supports the hypothesis of extensive horizontal gene transfer events between the various pyogenic streptococcal species belonging to Lancefield groups A, C and G. A better understanding of the mechanisms of pathogenesis should be apparent by whole-genome sequencing, and this would result in more effective clinical strategies for the pyogenic group in general.

Risk factors associated with bacteremia correlated with mortality in patients with acute bacterial skin and skin structure infection

Acute bacterial skin and skin structure infections (ABSSSI) is a common cause of acute admissions worldwide, but the disease is not well understood epidemiologically with respect to factors that determine positive blood cultures or patient mortality. To understand the utility of blood cultures and the association between bacteremia and mortality in patients with ABSSSI, we conducted a retrospective study to investigate factors associated with positive blood cultures and mortality in patients with ABSSSI. A retrospective cohort study of hospitalized adult patients with ABSSSI was conducted in a tertiary hospital in Taiwan between March 2015 and December 2016. A total of 1322 hospitalized patients with ABSSSI are included. The overall mortality rate is 2.1% (28/1322), and 122 patients had positive blood culture results. Comorbidities that are significant risk factors for a positive blood culture include diabetes mellitus and chronic kidney disease. Significant risk factors evident in laboratory evaluations include high C-reactive protein (CRP) level (> 20 mg/dL), hyperglycemia, and hypoalbuminemia. Bacteremia is also a significant factor associated with mortality. A blood culture should be considered for patients with ABSSSI with diabetes mellitus or chronic kidney disease or those exhibiting abnormal CRP, glucose, or albumin levels because of the positive correlation between bacteremia and mortality.

Skin and Soft Tissue Infections in the Emergency Department

This article covers the diagnosis and treatment of skin and soft tissue infections commonly encountered in the emergency department: impetigo, cutaneous abscesses, purulent cellulitis, nonpurulent cellulitis, and necrotizing skin and soft tissue infections. Most purulent infections in the United States are caused by methicillin-resistant Staphylococcus aureus. For abscesses, we emphasize the importance of incision and drainage. Nonpurulent infections are usually caused by streptococcal species and initial empiric antibiotics need not cover methicillin-resistant Staphylococcus aureus. For uncommon but potentially lethal necrotizing skin and soft tissue infections, the challenge is rapid diagnosis in the emergency department and prompt surgical exploration and debridement.

Fulminant Staphylococcal Infections

Fulminant staphylococcal infection indicates an explosive, intense, and severe infection occurring in a patient whose previous condition and antecedent would never have caused any anticipation of life-threatening development. This includes necrotizing pneumonia, necrotizing fasciitis, and to some extent toxic shock syndrome and infective endocarditis. In the three former diseases, toxin production plays a major role whereas in the latter (fulminant presentation of infective endocarditis), association with any particular toxinic profile has never been demonstrated. This article reviews the clinical, pathophysiological, and therapeutic aspects of these diseases.

A Case of Recurrent Erysipelas Caused by Streptococcus mitis Group

The aetiology of erysipelas remains poorly defined though beta-haemolytic streptococci are considered as the main causative pathogens. We describe a case of a 70-year-old woman with recurrent erysipelas in her left arm due to infection with streptococci of the mitis group. Her past medical history includes lymphoedema of the left arm secondary to lymph node dissection due to breast cancer surgery. On seven different occasions during a decade, she has presented a clinical picture of erysipelas and in three of them with Streptococcus mitis group bacteraemia. The results indicate that two cases were caused by Streptococcus mitis and one case was caused by Streptococcus oralis. This is, to our knowledge, the first reported cases of S. mitis and of S. oralis as the causative agents of erysipelas.

Which outcomes are reported in cellulitis trials? Results of a review of outcomes included in cellulitis trials and a patient priority setting survey

BACKGROUND

There is an emerging need to develop consistent outcomes in clinical trials to allow effective comparison of treatment effects. No systematic review has previously looked at the reporting of outcome measures used in randomized controlled trials (RCTs) on the treatment and prevention of cellulitis (erysipelas).

OBJECTIVES

The primary aim of this review was to describe the breadth of outcomes reported from RCTs on cellulitis treatment and prevention. The secondary aim was to identify outcome themes from patients' and healthcare professionals' feedback from a cellulitis Priority Setting Partnership (PSP).

METHODS

We conducted a review of all outcome measures used in RCTs from two recent Cochrane reviews. Free-text responses from a cellulitis priority setting survey were used to understand the perspectives of patients and healthcare professionals.

RESULTS

Outcomes from 42 RCTs on treatment of cellulitis and six RCTs on prevention of cellulitis were reviewed. Only 28 trials stated their primary outcome. For trials assessing treatment of cellulitis, clinical response to treatment was categorized in 25 different ways. Five of these trials used an outcome that was in accordance with FDA guidance and only four trials incorporated either quality of life or patient satisfaction. For trials assessing prevention of cellulitis, recurrence was the key outcome measure. From the cellulitis PSP, prevention of recurrence, clinical features and long-term disease impact were the most important outcome themes for patients.

CONCLUSIONS

We have shown that in cellulitis treatment and prevention research, there is significant heterogeneity in clinical outcomes, inadequate focus on patient-reported outcomes, and a disparity between what is currently measured and what patients and healthcare professionals feel is important. We recommend that future cellulitis treatment trials consider the use of longer-term outcomes to capture recurrence and long-term morbidity, as well as short-term resolution of acute infection.

Cellulitis and Soft Tissue Infections

Cellulitis and soft tissue infections are a diverse group of diseases that range from uncomplicated cellulitis to necrotizing fasciitis. Management of predisposing conditions is the primary means of prevention. Cellulitis is a clinical diagnosis and thus is made on the basis of history and physical examination. Imaging may be helpful for characterizing purulent soft tissue infections and associated osteomyelitis. Treatment varies according to the type of infection. The foundations of treatment are drainage of purulence and antibiotics, the latter targeted at the infection's most likely cause.

Guidelines vs Actual Management of Skin and Soft Tissue Infections in the Emergency Department

Background

Infections of skin and soft tissue (SSTI) commonly cause visits to hospital emergency departments (EDs). The Infectious Diseases Society of America (IDSA) has published guidelines for the management of SSTI, but it is unclear how closely these guidelines are followed in practice.

Methods

We reviewed records of patients seen in the ED at a large tertiary care hospital to determine guidelines adherence in 4 important areas: the decision to hospitalize, choice of antibiotics, incision and drainage (I&D) of abscesses, and submission of specimens for culture.

Results

The decision to hospitalize did not comply with guidelines in 19.6% of cases. Nonrecommended antibiotics were begun in the ED in 71% of patients with nonpurulent infections and 68.4% of patients with purulent infections. Abscesses of mild severity were almost always treated with antibiotics, and I&D was often not done (both against recommendations). Blood cultures were done (against recommendations) in 29% of patients with mild-severity cellulitis. Abscess drainage was almost always sent for culture (recommendations neither favor nor oppose). Overall, treatment fully complied with guidelines in 20.1% of cases.

Conclusions

Our results show a striking lack of concordance with IDSA guidelines in the ED management of SSTI. Social factors may account for discordant decisions regarding site of care. Use of trimethoprim/sulfamethoxazole (TMP/SMX) in cellulitis was the most common source of discordance; this practice is supported by some medical literature. Excess antibiotics were often used in cellulitis and after I&D of simple abscesses, opposing antibiotic stewardship. Ongoing education of ED doctors and continued review of published guidelines are needed.

Aetiology and clinical features of facial cellulitis: a prospective study

BACKGROUND

In the early 20th century, the face was the predominant site of cellulitis. Despite a relative decrease in the incidence of facial cellulitis, it is still common. There are few studies on this condition during the last decades. The aim of this study was to describe contemporary aetiological and clinical characteristics of patients admitted to hospital with non-suppurative facial cellulitis.

METHODS

Patients were included prospectively. Clinical details, comorbidities and biochemistry results were recorded. Investigations included cultures of skin swab and blood and tests for streptococcal antibodies during the acute and convalescent stages.

RESULTS

Sixty-five patients were included. Serology, cultures and response to penicillin monotherapy identified probable or confirmed β-haemolytic streptococci (BHS) aetiology in 75% (49/65) of cases. Significant comorbidities were present in 54% (35/65). Fever, chills or rigors before or at admission was noted in 91% (59/65). Patients presented most often with sharply demarcated erythema and raised borders (54/64). Penicillin or penicillinase-resistant penicillin alone or in combination cured 68% (44/65) of the patients. Supplementary clindamycin was used in 28% (18/65), most often only for 1-3 days. Only four patients needed a second course of antibiotics. Clinical failure was more often seen in patients with non-BHS aetiology (p = .037). Few complications were noted; 14.5% (9/62) experienced transient diarrhoea, and only one had confirmed Clostridium difficile infection. No patients developed cerebral venous sinus thrombosis, and there were no fatalities.

CONCLUSIONS

Our findings indicate that BHS are the leading cause of facial cellulitis. Most patients exhibit sharply demarcated lesions and systemic symptoms. Narrow-spectrum β-lactam antibiotics and short hospital stay appear sufficient. Few complications and low recurrence rates were seen.

Interventions for the prevention of recurrent erysipelas and cellulitis

BACKGROUND

Erysipelas and cellulitis (hereafter referred to as 'cellulitis') are common bacterial skin infections usually affecting the lower extremities. Despite their burden of morbidity, the evidence for different prevention strategies is unclear.

OBJECTIVES

To assess the beneficial and adverse effects of antibiotic prophylaxis or other prophylactic interventions for the prevention of recurrent episodes of cellulitis in adults aged over 16.

SEARCH METHODS

We searched the following databases up to June 2016: the Cochrane Skin Group Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, and LILACS. We also searched five trials registry databases, and checked reference lists of included studies and reviews for further references to relevant randomised controlled trials (RCTs). We searched two sets of dermatology conference proceedings, and BIOSIS Previews.

SELECTION CRITERIA

Randomised controlled trials evaluating any therapy for the prevention of recurrent cellulitis.

DATA COLLECTION AND ANALYSIS

Two authors independently carried out study selection, data extraction, assessment of risks of bias, and analyses. Our primary prespecified outcome was recurrence of cellulitis when on treatment and after treatment. Our secondary outcomes included incidence rate, time to next episode, hospitalisation, quality of life, development of resistance to antibiotics, adverse reactions and mortality.

MAIN RESULTS

We included six trials, with a total of 573 evaluable participants, who were aged on average between 50 and 70. There were few previous episodes of cellulitis in those recruited to the trials, ranging between one and four episodes per study.Five of the six included trials assessed prevention with antibiotics in participants with cellulitis of the legs, and one assessed selenium in participants with cellulitis of the arms. Among the studies assessing antibiotics, one study evaluated oral erythromycin (n = 32) and four studies assessed penicillin (n = 481). Treatment duration varied from six to 18 months, and two studies continued to follow up participants after discontinuation of prophylaxis, with a follow-up period of up to one and a half to two years. Four studies were single-centre, and two were multicentre; they were conducted in five countries: the UK, Sweden, Tunisia, Israel, and Austria.Based on five trials, antibiotic prophylaxis (at the end of the treatment phase ('on prophylaxis')) decreased the risk of cellulitis recurrence by 69%, compared to no treatment or placebo (risk ratio (RR) 0.31, 95% confidence interval (CI) 0.13 to 0.72; n = 513; P = 0.007), number needed to treat for an additional beneficial outcome (NNTB) six, (95% CI 5 to 15), and we rated the certainty of evidence for this outcome as moderate.Under prophylactic treatment and compared to no treatment or placebo, antibiotic prophylaxis reduced the incidence rate of cellulitis by 56% (RR 0.44, 95% CI 0.22 to 0.89; four studies; n = 473; P value = 0.02; moderate-certainty evidence) and significantly decreased the rate until the next episode of cellulitis (hazard ratio (HR) 0.51, 95% CI 0.34 to 0.78; three studies; n = 437; P = 0.002; moderate-certainty evidence).The protective effects of antibiotic did not last after prophylaxis had been stopped ('post-prophylaxis') for risk of cellulitis recurrence (RR 0.88, 95% CI 0.59 to 1.31; two studies; n = 287; P = 0.52), incidence rate of cellulitis (RR 0.94, 95% CI 0.65 to 1.36; two studies; n = 287; P = 0.74), and rate until next episode of cellulitis (HR 0.78, 95% CI 0.39 to 1.56; two studies; n = 287). Evidence was of low certainty.Effects are relevant mainly for people after at least two episodes of leg cellulitis occurring within a period up to three years.We found no significant differences in adverse effects or hospitalisation between antibiotic and no treatment or placebo; for adverse effects: RR 0.87, 95% CI 0.58 to 1.30; four studies; n = 469; P = 0.48; for hospitalisation: RR 0.77, 95% CI 0.37 to 1.57; three studies; n = 429; P = 0.47, with certainty of evidence rated low for these outcomes. The existing data did not allow us to fully explore its impact on length of hospital stay.The common adverse reactions were gastrointestinal symptoms, mainly nausea and diarrhoea; rash (severe cutaneous adverse reactions were not reported); and thrush. Three studies reported adverse effects that led to discontinuation of the assigned therapy. In one study (erythromycin), three participants reported abdominal pain and nausea, so their treatment was changed to penicillin. In another study, two participants treated with penicillin withdrew from treatment due to diarrhoea or nausea. In one study, around 10% of participants stopped treatment due to pain at the injection site (the active treatment group was given intramuscular injections of benzathine penicillin).None of the included studies assessed the development of antimicrobial resistance or quality-of-life measures.With regard to the risks of bias, two included studies were at low risk of bias and we judged three others as being at high risk of bias, mainly due to lack of blinding.

AUTHORS' CONCLUSIONS

In terms of recurrence, incidence, and time to next episode, antibiotic is probably an effective preventive treatment for recurrent cellulitis of the lower limbs in those under prophylactic treatment, compared with placebo or no treatment (moderate-certainty evidence). However, these preventive effects of antibiotics appear to diminish after they are discontinued (low-certainty evidence). Treatment with antibiotic does not trigger any serious adverse events, and those associated are minor, such as nausea and rash (low-certainty evidence). The evidence is limited to people with at least two past episodes of leg cellulitis within a time frame of up to three years, and none of the studies investigated other common interventions such as lymphoedema reduction methods or proper skin care. Larger, high-quality studies are warranted, including long-term follow-up and other prophylactic measures.

Early Response in Cellulitis: A Prospective Study of Dynamics and Predictors

In this prospective study of cellulitis, several nonpharmacological factors were associated with lack of early response. Such early nonresponse was rarely related to inappropriate therapy but strongly predictive of early treatment escalation, suggesting that broadening antibiotic treatment often may be premature.

Background. Skin and soft tissue infections are common reasons for medical care. Use of broad-spectrum therapy and costs have increased. Assessment of early treatment response has been given a central role both in clinical trials and everyday practice. However, there is a paucity of data on the dynamics of response, causes of early nonresponse, and how early nonresponse affects resource use and predicts outcome.

Methods. We prospectively enrolled 216 patients hospitalized with cellulitis. Clinical and biochemical response data during the first 3 days of treatment were analyzed in relation to baseline factors, antibiotic use, surgery, and outcome. Multivariable analysis included logistic lasso regression.

Results. Clinical or biochemical response was observed in the majority of patients the day after treatment initiation. Concordance between clinical and biochemical response was strongest at days 2 and 3. Female sex, cardiovascular disease, higher body mass index, shorter duration of symptoms, and cellulitis other than typical erysipelas were predictors of nonresponse at day 3. In contrast, baseline factors were not predictive of clinical failure assessed posttreatment. Among cases with antibiotic treatment escalation by day 2, 90% (37/41) had nonresponse at day 1, but only 5% (2/40) had inappropriate initial therapy. Nonresponse at day 3 was a predictor of treatment duration >14 days, but not of clinical failure.

Conclusions. Nonpharmacological factors had a major impact on early response dynamics. Delayed response was rarely related to inappropriate therapy but strongly predictive of early treatment escalation, suggesting that broadening antibiotic treatment may often be premature.