Retrospective Clinical and Microbiologic Analysis of Patients with Anorectal Abscess

Causal relationship between obesity and anorectal abscess: a Mendelian randomization study

Background

Observational studies have indicated that obesity is a risk factor for anorectal abscess (ARB). However, it remains unclear whether a causal genetic relationship exists between obesity and ARB.

Methods

Univariate and multivariate Mendelian randomization (MR) were conducted using data from a large, published genome-wide association study (GWAS) of European ancestry to infer a causal relationship between obesity and ARB. Inverse variance weighted (IVW) analysis served as the primary analysis method, with results reported as odds ratios (OR).

Results

MR analysis revealed that body mass index (BMI) positively affects ARB (OR 1.974, 95% confidence interval (CI) 1.548-2.519, p = 4.34 × 10-8). The weighted median method (OR = 1.879, 95% CI 1.248-2.829, p = 0.002) and Bayesian model averaging (BMA) (OR = 1.88, 95% CI 1.477-2.392, p = 2.85 × 10-7) also demonstrated consistent results. Subsequently, the impact of several obesity-related characteristics on ARB was assessed. Body fat percentage (BF), whole body fat mass (FM), waist circumference (WC), and hip circumference (HC) were found to be causally associated with an increased risk of ARB. However, these associations vanished after adjusting for BMI effects.

Conclusion

The study confirms a positive causal effect of obesity on ARB, highlighting that reasonable weight control is an important strategy to reduce the incidence of ARB.

Aerobic Microbiological Spectrum and Antibiotic Resistance in Children Operated for Anorectal Abscesses

(1) Background: Anorectal abscesses are a relatively rare pathology in childhood. Most often, male children under 1 year of age are affected. The importance of microbiological examination for the diagnosis and treatment of such patients remains debatable among surgeons, resulting in scarce data being available in the literature. We aimed to identify the aerobic microbiological spectrum and antibiotic resistance of isolates in children undergoing operation to treat anorectal abscesses. (2) Methods: We performed a case series of 102 children diagnosed and operated for anorectal abscesses over a period of 10 years (2010-2019). Purulent wound exudate was used for microbiological evaluation, which was subsequently cultured on 5% sheep-blood agar and eosin-methylene blue agar. For microbiological identification, conventional biochemical tests and semi-automated (API 20, bioMerieux, Marcy-l'Étoile, France) tests were used, as well as automated systems (Vitek-2 Compact, bioMerieux, France). Antimicrobial susceptibility testing was performed by the disk diffusion method of Bauer-Kirby and by determining the minimal inhibitory concentrations for glycopeptides. The results were interpreted according to the EUCAST standard for the corresponding year. (3) Results: Microbiological testing in children operated for anorectal abscesses mainly identified the gut commensals that normally reside in the rectal mucosa. Monocultures were found in just over half of the cases. Escherichia coli, Klebsiella pneumoniae complex, and Proteus mirabilis were the most frequently isolated. In addition, Staphylococcus aureus was found in 7% of patients. In Gram-negative bacteria, antibiotic resistance was most often observed in penicillins, cephalosporins, sulfonamides, and fluoroquinolones. (4) Conclusions: The increasing rates of antimicrobial resistance impose the need for the local monitoring of circulating commensal bacteria associated with anorectal abscesses in children to guide antibiotic therapy when indicated.

Microbiota in adult perianal abscess revealed by metagenomic next-generation sequencing

The microbiota of perianal abscesses is scarcely investigated. Identifying causative bacteria is essential to develop antibiotic therapy. However, culture-based methods and molecular diagnostics through 16S PCR technology are often hampered by the polymicrobial nature of perianal abscesses. We sought to characterize the microbiota composition of perianal abscesses via metagenomic next-generation sequencing (mNGS). Fourteen patients suffering from perianal abscesses between March 2023 and August 2023 underwent retrospective assessment. Information from medical records was used, including clinical information, laboratory data, and culture and mNGS results. Forty bacterial taxa were identified from perianal abscesses through mNGS, with Bilophila wadsworthia (71.4%), Bacteroides fragilis (57.1%), and Escherichia coli (50.0%) representing the most prevalent species. mNGS identified an increased number of bacterial taxa, with an average of 6.1 compared to a traditional culture-based method which only detected an average of 1.1 in culture-positive perianal abscess patients, predominantly E. coli (75.0%), revealing the polymicrobial nature of perianal abscesses. Our study demonstrates that a more diverse bacterial profile is detected by mNGS in perianal abscesses, and that Bilophila wadsworthia is the most prevalent microorganism, potentially serving as a potential biomarker for perianal abscess.IMPORTANCEAccurately, identifying the bacteria causing perianal abscesses is crucial for effective antibiotic therapy. However, traditional culture-based methods and 16S PCR technology often struggle with the polymicrobial nature of these abscesses. This study employed metagenomic next-generation sequencing (mNGS) to comprehensively analyze the microbiota composition. Results revealed 40 bacterial taxa, with Bilophila wadsworthia (71.4%), Bacteroides fragilis (57.1%), and Escherichia coli (50.0%) being the most prevalent species. Compared to the culture-based approach, mNGS detected a significantly higher number of bacterial taxa (average 6.1 vs 1.1), highlighting the complex nature of perianal abscesses. Notably, Bilophila wadsworthia emerged as a potential biomarker for these abscesses. This research emphasizes the importance of mNGS in understanding perianal abscesses and suggests its potential for improving diagnostic accuracy and guiding targeted antibiotic therapy in the future.

Fistula development after anal abscess drainage-a multicentre retrospective cohort study

PURPOSE

Anal abscesses are common and, despite correct treatment with surgical drainage, carry the risk of developing fistulas. Studies identifying risk factors for the development of anal fistulas are sparse. This study aimed to identify the risk factors for anal fistulas after anal abscess surgery.

METHODS

This was a multicentre, retrospective cohort study of patients undergoing acute surgery for anal abscesses in the Capital Region of Denmark between 2018 and 2019. The patients were identified using ICD-10 codes for anal abscesses. Predefined clinicopathological factors and postoperative courses were extracted from patient records.

RESULTS

A total of 475 patients were included. At a median follow-up time of 1108 days (IQR 946-1320 days) following surgery, 164 (33.7%) patients were diagnosed with an anal fistula. Risk factors for developing fistulas were low intersphincteric (OR 2.77, 95CI 1.50-5.06) and ischioanal (OR 2.48, 95CI 1.36-4.47) abscesses, Crohn's disease (OR 5.96, 95CI 2.33-17.2), a history of recurrent anal abscesses (OR 4.14, 95CI 2.47-7.01) or repeat surgery (OR 5.96, 95CI 2.33-17.2), E. coli-positive pus cultures (OR 4.06, 1.56-11.4) or preoperative C-reactive protein (CRP) of more than 100 mg/L (OR 3.21, 95CI 1.57-6.71).

CONCLUSION

Several significant clinical risk factors were associated with fistula development following anal abscess surgery. These findings are clinically relevant and could influence the selection of patients for specialised follow-up, facilitate expedited diagnosis, and potentially prevent unnecessarily long treatment courses.

New Perianal Sepsis Risk Score Predicts Outcome of Elderly Patients with Perianal Abscesses

Antibiotic therapy following surgical perianal abscess drainage is debated, but may be necessary for high-risk patients. Frailty has been shown to increase the risk of unfavorable outcomes in elderly surgical patients. This study aims to identify high-risk patients by retrospectively analyzing a single-center cohort and using a pretherapeutic score to predict the need for postoperative antibiotics and extended nursing care following perianal abscess drainage surgery. The perianal sepsis risk score was developed through univariable and multivariable analysis. Internal validation was assessed using the area under receiver-operating characteristic curve. Elderly, especially frail patients exhibited more severe perianal disease, higher frequency of antibiotic therapy, longer hospitalization, poorer clinical outcomes. Multivariable analysis revealed that scores in the 5-item modified frailty index, severity of local infection, and preoperative laboratory markers of infection independently predicted the need for prolonged hospitalization and anti-infective therapy after abscess drainage surgery. These factors were combined into the perianal sepsis risk score, which demonstrated better predictive accuracy for prolonged hospitalization and antibiotic therapy compared with chronological age or frailty status alone. Geriatric assessments are becoming increasingly important in clinical practice. The perianal sepsis risk score identifies high-risk patients before surgery, enabling early initiation of antibiotic therapy and allocation of additional nursing resources.

Drug resistant bacteria in perianal abscesses are frequent and relevant

Perianal abscesses are frequent diseases in general surgery. Principles of standard patient care are surgical drainage with exploration and concomitant treatment of fistula. Antiinfective therapy is frequently applied in cases of severe local disease and perianal sepsis. However, the role of microbiologic testing of purulence from perianal abscesses is disputed and the knowledge concerning bacteriology and bacterial resistances is very limited. A retrospective cohort study was performed of consecutive patients (≥ 12 years of age) from a tertiary care hospital, who underwent surgical treatment for perianal abscess from 01/2008 to 12/2019. Subdividing the cohort into three groups regarding microbiological testing results: no microbiological testing of purulence (No_Swab, n = 456), no detection of drug resistant bacteria [DR(−), n = 141] or detection of bacteria with acquired drug resistances from purulence [DR(+), n = 220]. Group comparisons were performed using Kruskall–Wallis test and, if applicable, followed by Dunn´s multiple comparisons test for continuous variables or Fishers exact or Pearson’s X² test for categorical data. Fistula persistence was estimated by Kaplan Meier and compared between the groups using Log rank test. Corralation analysis between perioperative outcome parameters and bacteriology was performed using Spearman´s rho rank correlation. Higher pretherapeutic C-reactive protein (p < 0.0001) and white blood cell count (p < 0.0001), higher rates of supralevatoric or pararectal abscesses (p = 0.0062) and of complicated fistula-in-ano requiring drainage procedure during index surgery (p < 0.0001) reflect more severe diseases in DR(+) patients. The necessity of antibiotic therapy (p < 0.0001), change of antibiotic regimen upon microbiologic testing results (p = 0.0001) and the rate of re-debridements during short-term follow-up (p = 0.0001) were the highest, the duration until definitive fistula repair was the longest in DR(+) patients (p = 0.0061). Escherichia coli, Bacteroides, Streptococcus and Staphylococcus species with acquired drug resistances were detected frequently. High rates of resistances against everyday antibiotics, including perioperative antibiotic prophylaxis were alarming. In conclusion, the knowledge about individual bacteriology is relevant in cases of complex and severe local disease, including locally advanced infection with extended soft tissue affection and perianal sepsis, signs of systemic inflammatory response as well as the need of re-do surgery for local debridements during short-term and fistula repair during long-term follow-up. Higher rates of acquired antibiotic resistances are to be expected in patients with more severe diseases.

Treatment of anal fistula with Baccharis dracunculifolia extract. Experimental study in rats

OBJECTIVE

to evaluate the efficacy of Baccharis dracunculifolia extract in the treatment of anal fistulas in rats.

METHODS

twenty male Wistar rats were submitted to anal fistula and, after 30 days, were divided into three groups: Control Group, with five animals; Carbopol Group, with five animals; and Baccharis dracunculifolia Group, with ten animals. In the Control Group, no treatment was performed. In the Carbopol Group, a daily infusion of Carbopol was performed for 30 days. In the Baccharis dracunculifolia Group, a daily infusion of Carbopol plus Baccharis dracunculifolia extract was performed for 30 days. Specimens were taken for histological analysis after euthanasia.

RESULTS

there was no complete closure of the fistulous tract in any of the animals. The mean area of the remaining tract was of 847.2µm2, 565.6µm2 and 372.7µm2, in the Control Group, Carbopol Group, and Baccharis dracunculifolia Group, respectively, (p=0.001). The mean of the inflammatory process score was of 2.4, 2.4, and 2.1, in the Control Group, Carbopol Group, and Baccharis dracunculifolia Group, respectively, (p=0.285), while the mean values of vascular congestion were of 1.6, 1.4, and 1.1, in the Control Group, Carbopol Group, and Baccharis dracunculifolia Group, respectively, (p=0.031).

CONCLUSION

Baccharis dracunculifolia extract was able to reduce the lumen of the fistulous tracts and the degree of vascular congestion, without, however, reducing the local inflammatory process or totally closing the fistulous tracts.