Anorectal sepsis: microbiology in relation to fistula-in-ano

The Role of Magnetic Resonance Imaging in Pre-operative Assessment of Anorectal Fistula With Surgical Correlation

Background Anorectal fistulas are chronic inflammations of peri-anal tissues that form a connection between the perineal skin and the anal canal. Accurate preoperative evaluation of the main fistula's trajectory and pelvic tissues is essential for effective surgical treatment of anal fistulas. The inability to detect concealed lesions may result in the recurrence of fistulas and the conversion of a simple fistula into a complex fistula. Magnetic resonance imaging (MRI) imaging can detect concealed pathways and abscesses, thereby exposing the intricate connection between the fistula and anal-sphincter complex. This data serves as a roadmap for making surgical decisions, thereby reducing the likelihood of illness recurrence and complications after surgery. Aim To evaluate the role of MRI in pre-operative assessment of an anorectal fistula, compare its findings with surgical results. Materials and methods The research was conducted at the Radiology Department, Apollo Hospital, Hyderabad. It was a prospective observational study. IBM SPSS Statistics for Windows, Version 17 (released 2008; IBM Corp., Armonk, New York, United States) was utilized for data analysis. The mean and standard deviation were computed. We further applied appropriate statistical tests to determine the significance of MRI features with pre-operative findings. Results MRI accurately detects features like abscesses (sensitivity-100%, specificity-97.06%), secondary tracts of the fistula (sensitivity-93.55%, specificity-94.12%), horseshoe appearance, and supralevator extension (sensitivity-100%, specificity-97.50%, and 97.62%, respectively). Conclusion When comparing our results with intraoperative findings, MRI showed high sensitivity and specificity in detecting abscesses, secondary tracts, horseshoe appearances, and supralevator extensions. Our findings suggest that MRI can offer anatomical and pathological information for the pre-operative care and surgical planning of perianal fistulas.

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.

Anal abscess microbiology as an anal fistula predictor

In order to determine the microbiology of anal abscess as a predictor of anal fistulas in patients who attended the external consultation of the Coloproctology unit of the Dr. Antonio María Pineda University Central Hospital, a prospective, descriptive, longitudinal study was conducted from September 2018 to July 2019. In this study, the population consisted of patients with a diagnosis of anal abscess, without associated comorbidities or contraindications for surgery, who agreed to be included in the study. A non-probabilistic, intentional sample consisting of 42 patients was determined. An appointment-based study protocol was applied by outpatient for patients who met the inclusion criteria applied, to perform due medical history through anamnesis, physical examination and culture taking of suppuration from the anal abscess to subsequently establish medical and surgical behavior thereof. The results were expressed in absolute numbers and percentages, a prevalence of ischiorectal abscesses was observed, followed by deep post-anal space abscesses. Anaerobic bacteria were isolated in 100% of the sample. In all fistulized patients, E. Coli was isolated as a predominant germ.

Persistent Fistula After Anorectal Abscess Drainage: Local Experience of 11 Years

BACKGROUND

The characteristics of patients who develop a fistula-in-ano after an anorectal abscess are unclear.

OBJECTIVE

Our study explored this relationship and patient factors associated with fistula development.

DESIGN

International Classification of Diseases, 10 Revision, and Classification of Interventions and Procedures, version 4, codes were used to identify all of the patients with a primary anorectal abscess. Multivariable analysis was used to identify factors predictive of fistula formation.

SETTINGS

The study was conducted in a district general hospital.

PATIENTS

Patients with anorectal abscess who were admitted to our institution (2004-2015) were included.

MAIN OUTCOMES MEASURES

The rate of subsequent fistula formation was measured.

RESULTS

A total of 1970 abscess patients were identified; 70.0% (n = 1379) were men, and 7.3% (n = 144) had Crohn's disease. Fistulas occurred in 16.2% (n = 319) at a median of 7 months (interquartile range, 3-7 mo). Patients with Crohn's disease were more than twice as likely to develop a fistula than patients without Crohn's disease (32.6% vs 14.9%; OR = 2.5 (95% CI, 1.7-3.7); p < 0.001). Patients with Crohn's disease with a fistula were more likely to be women (55.3% vs 34.6%; p = 0.007) and aged <30 years (51.1% vs 24.3%; p< 0.001) versus patients without Crohn's disease with a fistula. At multivariable analysis of the entire cohort, male sex (OR = 0.7 (95% CI, 0.5-0.9); p = 0.005) and diabetes mellitus (OR = 0.5 (95% CI, 0.3-0.9); p = 0.027) were associated with a reduced likelihood of developing a fistula after abscess formation.

LIMITATIONS

The study was limited by its single-center scope, retrospective analysis, and lack of a standardized definition for Crohn's disease.

CONCLUSIONS

Abscesses are more common in men, but progression to fistula is more likely in women. The rate of fistula progression in Crohn's disease is twice that in patients without Crohn's disease. Identification of patients at risk may help delineate those who will benefit from a more conservative surgical approach, enhanced follow-up, or investigation after abscess drainage. See Video Abstract at http://links.lww.com/DCR/A798.

Review article: pathogenesis of Crohn's perianal fistula-understanding factors impacting on success and failure of treatment strategies

BACKGROUND

Evidence from groups who have studied fistula aetiology and extrapolation from interventional studies supports a multifactorial hypothesis of Crohn's perianal fistula, with several pathophysiological elements that may contribute to fistula formation, persistence and resistance to treatment.

AIM

An evidence synthesis of current understanding of pathophysiological factors underlying Crohn's perianal fistula is presented, exploring the fundamental reasons why some treatments succeed and others fail, as a means of focussing clinical knowledge on improving treatment of Crohn's perianal fistula.

METHODS

Evidence to support this review was gathered via the Pubmed database. Studies discussing pathophysiological factors underpinning perianal fistula, particularly in Crohn's disease, were reviewed and cross-referenced for additional reports.

RESULTS

Pathophysiological factors that impact on success or failure of interventions for Crohn's perianal fistulae include the high-pressure zone, obliterating the dead space, disconnecting the track from the anus, removing epithelialisation, eradicating sepsis and by-products of bacterial colonisation, correcting abnormalities in wound repair and removing the pro-inflammatory environment which allows fistula persistence. Most current interventions for Crohn's perianal fistulae tend to focus on a single, or at best two, aspects of the pathophysiology of Crohn's anal fistulae; as a result, failure to heal fully is common.

CONCLUSIONS

For an intervention or combination of interventions to succeed, multiple factors must be addressed. We hypothesise that correct, timely and complete attention to all of these factors in a multimodal approach represents a new direction that may enable the creation of an effective treatment algorithm for Crohn's anal fistula.

The treatment of anal fistula: second ACPGBI Position Statement - 2018

It is over 10 years since the first ACPGBI Position Statement on the management of anal fistula was published in 2007. This second edition is the result of scrutiny of the literature published during this time; it updates the original Position Statement and reviews the published evidence surrounding treatments for anal fistula that have been developed since the original publication.

Pathogenesis and persistence of cryptoglandular anal fistula: a systematic review

Anal fistulas continue to be a problem for patients and surgeons alike despite scientific advances. While patient and anatomical characteristics are important to surgeons who are evaluating patients with anal fistulas, their development and persistence likely involves a multifaceted interaction of histological, microbiological, and molecular factors. Histological studies have shown that anal fistulas are variably epithelialized and are surrounded by dense collagen tissue with pockets of inflammatory cells. Yet, it remains unknown if or how histological differences impact fistula healing. The presence of a perianal abscess that contains gut flora commonly leads to the development of anal fistula. This implies a microbiological component, but bacteria are infrequently found in chronic fistulas. Recent work has shown an increased expression of proinflammatory cytokines and epithelial to mesenchymal cell transition in both cryptoglandular and Crohn's perianal fistulas. This suggests that molecular mechanisms may also play a role in both fistula development and persistence. The aim of this study was to examine the histological, microbiological, molecular, and host factors that contribute to the development and persistence of anal fistulas.

Assessment of microbiota and peptidoglycan in perianal fistulas

Transanal advancement flap repair has been advocated as the treatment of choice for high transsphincteric perianal fistulas, but fails in 1 of every 3 patients. Persistence of the fistula after flap repair might be the result of ongoing disease in the remaining fistula tract. In 10 specimens of the distal part of the fistula, microbiota was assessed by means of conventional microbiological culture and 16S rRNA gene sequencing. Proinflammatory bacterial peptidoglycan and recognition proteins were assessed by immunohistochemistry. Bacterial species were bowel derived, skin derived, or a combination of both. No mycobacterium species were identified. 16S rRNA gene sequencing failed to identify bacteria in all but 1 specimen, most likely as a result of low numbers of organisms. Peptidoglycan was detected in 90% of the patients, and a host response to peptidoglycan in 60%. Therefore, we suggest that peptidoglycan might play a role in the ongoing inflammation in perianal fistulas.

Does adjuvant antibiotic treatment after drainage of anorectal abscess prevent development of anal fistulas? A randomized, placebo-controlled, double-blind, multicenter study

BACKGROUND

The risk of fistula formation is a major concern after incision and drainage of an anorectal abscess.

OBJECTIVE

Our objective was to the test the effects of antibiotic treatment on fistula formation after incision and drainage of anorectal abscesses.

DESIGN

Randomized, placebo-controlled, double-blind study.

SETTING

Multicenter trial at 3 teaching hospitals in Turkey.

PATIENTS

Patients who underwent abscess drainage between September 2005 and January 2008 were evaluated for eligibility. Exclusion criteria included penicillin allergy, antimicrobial agent usage before enrolment, other infection, previous anorectal surgery, inflammatory bowel disease, suspicion of Fournier gangrene, secondary and recurrent anorectal abscesses, anal fistula at time of the surgery, immune compromised states, and pregnancy.

INTERVENTION

Patients were randomly assigned to receive placebo or amoxicillin-clavulanic acid combination treatment for 10 days after abscess drainage.

MAIN OUTCOME MEASURES

The primary end point was rate of anorectal fistula formation at 1-year follow-up.

RESULTS

: Of 334 patients assessed for eligibility, 183 entered the study (placebo, 92; antibiotics, 91). Data were available for per-protocol analysis from 151 patients (placebo, 76; antibiotics, 75) with a mean age of 37.6 years; 118 patients (78.1%) were men. Overall, 45 patients (29.8%) developed anal fistulas during 1-year follow-up. Fistula formation occurred in 17 patients (22.4%) in the placebo group and in 28 patients (37.3%) in the antibiotic group (P = .044). Risk of fistula formation was increased in patients with ischiorectal abscess (odds ratio, 7.82) or intersphincteric abscess (odds ratio, 3.35) compared with perianal abscess.

CONCLUSION

Antibiotic treatment following the drainage of an anorectal abscess has no protective effect regarding risk of fistula formation.

The impact of specialist experience in the surgical management of perianal abscesses

Perianal abscesses are one of the most common general surgical emergencies and the management of this can be variable. The aim of our study was to assess the management strategy used by different grades of surgeons in the surgical management of an acute perianal abscess.

MATERIAL AND METHODS

A retrospective analysis was carried out of all patients presenting with an abscess in the perianal region over a two-year period from January 2006 to December 2007. Patient demographics and co-morbidities were noted. The management strategies of different grades of operating surgeon were analysed.

RESULTS

During the two-year period, 147 patients presented with a perianal abscess of whom 52 (28%) had recurrent abscess. Fistulae were identified in 30 patients, with more than half picked up by consultants (P = 0.00001). Consultants performed fistulotomy and Seton insertion in 50% and 17% of patients respectively, whilst registrars performed these procedures in only 4% and 8% of patients (p < 0.00001).

CONCLUSION

Whilst surgical management of the perianal abscess is one of the most common surgical emergency procedures performed by the surgical trainees, input from a senior clinician improves the identification and definitive management of an underlying fistula. This study reinforces the importance of involvement of senior surgeons in the management of this common condition.

Thread-dragging therapy in treatment of a rat model of infected subcutaneous fistula

OBJECTIVE

This study was to develop an experimental rat model of subcutaneous fistula induced by bacteria infection and treat it with thread-dragging therapy.

METHODS

A spring-gauze was surgically implanted into 24 male Sprague-Dawley rats' dorsal muscles, respectively, then mixed Staphylococcus aureus and Escherichia coli were injected into the spring-gauze. After 45 d, all the spring-gauzes were removed from the rats under anesthesia. X-ray and ultrasound were performed to assess the fistula tract. Each rat was examined by a fistula probe and four rats were randomly selected for histological assessment. The residual rats were randomly divided into two groups. Group A was treated with thread-dragging therapy, and group B was treated with fistulotomy. The healing time and body weight of the two groups were compared.

RESULTS

On the 45th day of the spring-gauze implantation, imaging assessment proved a tract with two openings in all rats and histological results proved that lumen and surrounding granulation tissue with epithelium were similar to the features of fistula in human beings. The mean healing time of rats in group A was shorter than that of the rats in group B (P<0.01). The body weight of rats in group A was heavier than that of the rats in group B on the 7th and 14th day after surgery, respectively (P<0.05).

CONCLUSION

A rat model of subcutaneous fistula induced by mixed Staphylococcus aureus and Escherichia coli infection was successfully established. Traditional Chinese medicine thread-dragging therapy is less invasive and safer than fistulotomy.

Supralevator fistula-in-ano in tuberculosis

AIM

Perianal Mycobacterium tuberculosis is rare, but tuberculosis (TB) is now endemic in many areas of the world. It is essential to recognize TB to institute appropriate management. We report three cases of TB presenting with supralevator abscess.

METHOD

We analysed the outcomes of three patients who presented to our unit, from 2004 to 2009, with supralevator abscess caused by TB.

RESULTS

The patients presented as emergencies with symptoms of per-anal sepsis. All required multiple drainage procedures. Supralevator extension was confirmed clinically and radiologically (by magnetic resonance imaging in two patients and by computed tomography scanning in one patient). One patient was diagnosed by perianal biopsy, the second by culture of pus and the third by sputum culture. Following drainage, all three patients were given anti-TB medication for 6 months. In all patients, the fistulae had high communication with the anal canal. In one patient, local drainage and medical therapy led to sepsis resolution, the second patient has residual complex fistulae and the third patient has recently commenced antimicrobial therapy.

CONCLUSION

As TB is endemic in many parts of Europe, TB should be suspected in patients with complex and/or recurrent perianal sepsis. Samples for histological and bacteriological analyses should be obtained from these patients. Recurrent perianal drainage procedures are likely to be required, and sepsis may persist after anti-TB therapy.

Clinical and microbiological analysis of adult perianal abscess

BACKGROUND

In Taiwan, Klebsiella pneumoniae is the predominant pathogen causing pyogenic liver abscess in patients with diabetes mellitus (DM). The purpose of our hospital-based study was to determine the predominant bacterial species causing perianal abscess in hospitalized patients with and without DM in Taiwan.

METHODS

Data on patients admitted and then operated on for perianal abscess during the period of March 2001 to December 2008 were reviewed. Information extracted from medical records included clinical information and laboratory data as well as culture and antibiotic sensitivity results.

RESULTS

A total of 183 patients underwent surgery for perianal abscess. The most common pathogen causing perianal abscess in non-DM patients was Escherichia coli (67.1%), and the most common pathogen isolated in DM patients was K pneumoniae (60%; p=0.009). Among the 25 patients with DM, incident DM was diagnosed in 24.0% (6 of 25). In addition, five patients had transient hyperglycemia.

CONCLUSIONS

Escherichia coli was the predominant pathogen isolated from perianal abscesses in patients without DM. Klebsiella pneumoniae, however, was the predominant pathogen isolated in DM patients. In both DM and non-DM patients, more than 90% of K pneumoniae isolates showed in vitro sensitivity to first-generation cephalosporins.

MRSA-related perianal abscesses: an underrecognized disease entity

PURPOSE

Methicillin-resistant Staphylococcus aureus (MRSA) in perianal abscesses represents an underrecognized condition. It is unclear whether these abscesses differ in presentation or other characteristics from their non-MRSA counterparts.

METHODS

Patients diagnosed with perianal abscess, who underwent incision and drainage between January 2003 and September 2005, were identified retrospectively. Demographics, abscess characteristics (induration, erythema, abscess size, amount of purulence), presence of MRSA on culture, MRSA susceptibilities, and clinical course were collected.

RESULTS

A total of 104 patients (62.5 percent male; mean age, 42.7+/-13.7 years) were treated for perianal abscess. For the 69 patients cultured at drainage, MRSA was present in 34.8 percent (24/69) of cases (95 percent confidence interval, 24.6-46.6 percent). MRSA-positive patients did not significantly differ from MRSA-negative patients with respect to age, MRSA risk factors, duration of symptoms, white blood cell count at admission, or length of stay. Patients were more likely to be MRSA-positive if they possessed extensive induration (odds ratio, 6.52; P=0.003), extensive erythema (odds ratio, 5.75; P=0.003), or small amount of purulence (odds ratio, 9.72; P=0.006). Ischiorectal abscesses were significantly less likely to be MRSA-positive (odds ratio, 0.34; P=0.016). No patients with MRSA-positive abscesses developed fistulas. All MRSA isolates were resistant to beta-lactam antibiotics and had limited susceptibility to quinolones.

CONCLUSIONS

The prevalence of MRSA in perianal abscesses has not been described previously and is higher in our group of patients than would be expected. MRSA-positive patients cannot be identified by risk factors alone. Antibiotic resistance spectra of MRSA vary from that of enteric bacteria typically seen in perianal abscesses. Therefore, it may be beneficial to culture all perianal abscesses with extensive induration and erythema or minimal purulence.

Microbiological analysis and endoanal ultrasonography for diagnosis of anal fistula in acute anorectal sepsis

BACKGROUND AND AIMS

Treatment of anorectal sepsis requires prompt surgical drainage, but it is important to identify any associated anal fistula for preventing recurrence. We evaluated whether microbiological analysis and/or endoanal ultrasonography could be used to predict anal fistula in patients with acute anorectal sepsis.

METHODS

Five hundred fourteen consecutive patients with acute anorectal sepsis were studied. Clinical data, digital examination findings, endosonographic findings, and results of microbiological analysis were compared with definitive surgical findings of the presence or absence of anal fistula.

RESULTS

Anorectal abscess with anal fistula was found in 418 patients, and anorectal abscess without anal fistula was found in 96 patients. Microbiological examination showed that Escherichia coli, Bacteroides, Bacillus, and Klebsiella species were significantly more prevalent in patients with fistula (P<0.01), and coagulase-negative Staphylococci and Peptostreptococcus species were significantly more prevalent in patients without fistula (P<0.01). Results of endoanal ultrasonography were concordant with the definitive surgical diagnosis in 421 (94%) of 448 patients studied.

CONCLUSION

Acute anorectal sepsis due to colonization of "gut-derived" microorganisms rather than "skin-derived" organisms is more likely to be associated with anal fistula. When the microbiological analysis yields gut-derived bacteria, but no fistula has been found in the initial drainage operation, repeat examinations during a period of quiescence, including careful digital assessment and meticulous endosonography, are warranted to identify a potentially missed anal fistula.

Controversies in the treatment of common anal problems

Treating common benign anal diseases has evolved towards more outpatient procedures with better outcome. However, minimizing post-procedure morbidities such as pain and the avoidance incontinence remain the most significant concerns. We introduce some controversies and highlight the developments in current surgical practice for the treatment of common anal problems.

The role of surgery in the management of canine anal furunculosis. A review of the literature and a retrospective evaluation of treatment by surgical resection in 51 dogs

AIMS

To retrospectively evaluate the outcome of surgical management of anal furunculosis (AF) in 51 dogs. To compare the outcome of surgery with those of current medical protocols by way of a review of the literature.

METHODS

Dogs referred for treatment of AF (n=51) were treated by en bloc surgical resection of diseased tissue and primary wound closure. This technique was combined with bilateral anal sacculectomy in all cases in which the anal sacs had not been previously removed. Immunomodulatory therapies were not used, with the exception of post-operative metronidazole antibiosis for 7-10 days. Follow-up was performed by the author using a telephone questionnaire.

RESULTS

Forty-eight dogs were eligible for post-operative follow-up 1.5 to 36 (mean 17.4, median 18) months after surgery. Lesion recurrence, faecal incontinence and stricture formation occurred in 2%, 4% and 13% of dogs, respectively. The percentage of dogs considered by their owners to have an acceptable level of faecal continence and an improved quality of life was 94%.

CONCLUSIONS AND CLINICAL RELEVANCE

The aetiopathogenesis of canine AF remains unclear. Whilst recent advances in medical management by the use of various immunomodulatory medications (such as cyclosporine) hold promise, this approach has yet to be refined with respect to affordability, long-term efficacy and morbidity. With meticulous surgical dissection and reconstruction techniques (anoplasty), excellent success rates can be achieved following a single surgical procedure with minimal complications. Surgery remains a viable treatment option, alone or in combination with immunomodulatory medications, until a more thorough understanding of this debilitating disease is achieved.

Experimental model of fistula-in-ano

PURPOSE

This study was designed to create and evaluate an experimental porcine model of fistula-in-ano.

METHODS

Initial cadaveric dissection enabled refinement of the technique for fistula formation and histoanatomical study of the porcine anal canal. Subsequently, three surgically created fistulas were treated by seton drainage in each of eight male pigs (weight, 38-41 kg). After 26 days, magnetic resonance imaging at 1.5 Tesla was performed and setons removed under general anesthesia, enabling clinical and microbiologic track assessment. Two pigs were killed for histologic fistula track assessment.

RESULTS

Histoanatomical assessment noted a rudimentary internal anal sphincter, together with structures resembling anal glands. Artificial fistulas persisted during seton drainage and were more often associated with fecal than skin-derived organisms compared with both perineal and anal canal swabs (P = 0.002). All six fistulas assessed histologically had a lumen, and abundant surrounding granulation tissue similar to that seen in human fistula-in-ano. Epithelialization was not evident in any track. Fistulas were visualized as high signal tracks using magnetic resonance imaging.

CONCLUSIONS

Porcine anal anatomy resembles that of humans, and an experimental model proved suitable when assessed by magnetic resonance imaging, microbiology, and histologically, which demonstrated abundant granulation tissue. This model could be further used to investigate fistula treatments.

Role of microbiological investigations in the management of non-perineal cutaneous abscesses

BACKGROUND

Pus samples for microbiological examination are routinely sent after incision and drainage of abscesses. There is no evidence that microbiology reports influence treatment for non-perineal cutaneous abscesses.

AIMS

This study assessed (1) how often the microbiology report is used to manage patients' treatment after incision and drainage of an abscess and (2) junior surgical trainees' opinions on sending pus for microbiological examination.

METHOD

A retrospective analysis of the notes of all patients undergoing incision and drainage of abscesses from January 2001 to January 2002 was made. A telephone poll of junior surgical trainees was also undertaken.

RESULTS

Most patients, 91%, had specimens referred for microbiology. Of these 43% yielded no growth. Staphylococcus aureus was the most common organism (55.9% of all positive cultures). Anaerobes were a frequent finding from axilla and groin abscesses. Mycobacterium tuberculosis was grown in two patients. Other less common organisms cultured were methicillin resistant S aureus (n=1) and Proteus sp (n=1). Follow up of microbiology reports was found to be inadequate.

CONCLUSION

The bacteria present in non-perineal cutaneous abscesses are, for the most part, predictable. However, a significant number grow less common organisms. It is concluded that pus specimens should be sent routinely for culture and sensitivity and there should be further emphasis on following up microbiology reports by junior medical staff.

Colonization of the cleft nasal floor by anaerobic oral flora in patients with oronasal fistulae

OBJECTIVES

Aerobic oral bacteria only rarely colonize the cleft nasal floor in patients with patent oronasal fistula. There are no studies that have investigated whether anaerobic oral flora colonize this site and whether attempting to culture them is useful for assessing the patency of oronasal fistulae in the clinic.

DESIGN

A prospective study of 13 patients with cleft with patent unilateral oronasal fistulae. Microbiological culture swabs were taken from the oral cavity and both nasal floors, with the unaffected side being used as a control. Following aerobic and anaerobic culture, bacterial isolates were identified and compared.

MAIN OUTCOME MEASURE

A significant growth of anaerobic oral bacteria from the cleft nasal floor when compared with the unaffected side.

RESULTS

Aerobic oral flora was cultured from the oral cavity in all 13 patients. A light growth of aerobic oral flora was found in the cleft nasal floor in two patients, and anaerobic oral flora was cultured from the cleft nasal floor in the same two patients. No statistical correlation was found between growth of anaerobic flora and the cleft nasal floor (p =.48).

CONCLUSIONS

Like aerobic oral flora, anaerobic oral bacteria would appear to only rarely colonize the cleft nasal floor in patients with oronasal fistulae. This additional investigation does not appear to be helpful in the assessment of oronasal fistulae in the clinic.

Anorectal sepsis

Anorectal sepsis is a common cause of hospital admission, presenting with abscess or fistula formation. This article discusses the aetiology of acute anorectal sepsis and its management.

Do oral flora colonize the nasal floor of patients with oronasal fistulae?

OBJECTIVE

To determine if oral bacteria colonize the cleft nasal floor in patients with unilateral oronasal fistula when compared with the unaffected nasal floor and whether the results obtained would be of benefit in assessing oronasal fistulae in the clinic.

DESIGN

Prospective study of 26 patients with cleft palate and unilateral oronasal fistula. Microbiological culture swabs were taken from the mouth and nasal floors of patients. The unaffected nasal floor was used as a control. Bacterial isolates were identified and compared in the laboratory by a senior microbiologist.

MAIN OUTCOMES MEASURE

A significant growth of oral bacteria from the cleft nasal floor when compared with the unaffected nasal floor.

RESULTS

Four patients were excluded because no growth was found on any culture plate. In the remaining 22 cases, a light growth of oral flora was found in the cleft nasal floor in only 3 patients. No statistical correlation between culture of oral bacteria and the cleft nasal floor could be found (p =.12).

CONCLUSIONS

The relative lack of colonization of the cleft nasal floor by oral bacteria may reflect poor transmission of bacteria through the fistula, competition with commensal nasal flora, or an inability of oral bacteria to survive in a saliva-depleted area. The investigation is not helpful in the assessment of oronasal fistulae in the clinic.

Randomized controlled trial of primary fistulotomy with drainage alone for perianal abscesses

PURPOSE

Primary fistulotomy may be advantageous for perianal abscesses because unlike ischiorectal abscesses, fistulas are more commonly found and can be laid open with full preservation of the external anal sphincters. Therefore, a randomized, controlled trial was conducted to compare primary fistulotomy with incision and drainage alone, specifically for perianal abscesses.

METHODS

Fifty-two consecutive patients (43 males; mean age, 40 (standard error of mean, 2) years) with perianal abscesses were randomized to treatment by either incision and drainage (controls; N = 28) or fistulotomy (N = 24). Patients were followed up clinically for a mean of 15.5 (standard error of the mean, 0.7) months. Anorectal manometry was also performed before, six weeks, and three months after surgery.

RESULTS

Persistent fistulas developing after surgery were significantly more common after incision and drainage (N = 7; 25 percent) than after fistulotomy (N = 0; P = 0.009). One patient in each group was also found to have a residual abscess, which required repeat drainage. All patients remained fully continent. The anal pressures after incision and drainage and fistulotomy were not significantly different. Operative time, hospital stay, and time for the wound to heal completely were the same in both groups.

CONCLUSIONS

Primary fistulotomy at the time of drainage for perianal abscesses results in fewer persistent fistulas and no added risk of fecal incontinence.

Anorectal disorders

Anorectal disorders are commonly encountered in the practice of emergency medicine. Most can be diagnosed and treated in the emergency department setting. Almost all anorectal disorders once diagnosed and treated in the emergency department need appropriate follow-up to ensure adequacy of treatment, for further possible diagnostic procedures (e.g., endoscopy, biopsy), or for definitive treatment. Hemorrhoids are the most prevalent anorectal disorder and are the most common cause of hematochezia. Treatment is dependent on the degree of hemorrhoid prolapse and symptoms. Most cases can be treated by conservative medical treatment (e.g., dietary changes, sitz baths) or nonsurgical procedures (e.g., rubber band liagation, infrared coagulation). Surgical excision of symptomatic thrombosed external hemorrhoids is indicated if within 48 to 72 hours of pain onset. Anal fissures are one of the most common causes of anorectal pain. They are most frequently idiopathic, and most are located in the posterior midline of the anal canal. Most anal fissures are adequately treated by a medical approach using sitz baths, stool softeners, and analgesics. If the anal fissure becomes chronic and is not responsive to medical therapy, a lateral sphincterotomy of the internal anal sphincter is the surgical procedure of choice. Pharmacologic treatment (botulinum toxin or nitroglycerin ointment) to decrease internal anal sphincter tone has shown promise in the treatment of anal fissure. Anorectal abscesses are categorized into four types: perianal, ischiorectal, intersphincteric, and supralevator. Most are idiopathic and contain mixed aerobic-anaerobic pathogens. Fistula formation varies from 25% to 50% and is much more common with gut-derived organisms (e.g., E. coli, B. fragilis). Definitive treatment for an anorectal abscess is timely surgical incision and drainage to prevent more serious complications (e.g., serious infection, extension of the abscess). Anal carcinomas are infrequent, the majority of them being squamous cell or epidermoid carcinomas. The emergency physician must maintain a high index of suspicion and obtain a biopsy of suspicious lesions in order not to miss the diagnosis of a cancer. The most common presenting complaint of anal tumors is rectal bleeding. Combination chemotherapy and radiotherapy have shown promising results in the treatment of anal canal tumors. Bacterial, viral, and protozoal infections can be transmitted to the anorectum via anoreceptive intercourse. Such infections must be considered when a patient presents with rectal pain or discharge, tenesmus, or rectal or perineal ulcers. Proctosigmoidoscopy and rectal cultures may be necessary to determine the cause. Potential rectal complications of HIV infection include infectious diarrhea, acyclovir-resistant strains of HSV2, Kaposi's sarcoma, lymphoma, and squamous cell carcinoma. Rectal injuries may result from penetrating or blunt trauma, iatrogenic injuries, or foreign bodies. Rectal injury should be suspected when a patient presents with low abdominal, pelvic, or perineal pain or blood per rectum after sustaining trauma or undergoing an endoscopic or surgical procedure. Tetanus prophylaxis, intravenous antibiotics, and surgical intervention are indicated in all but superficial rectal tears.

Primary suture of anorectal abscess. A randomized study comparing treatment with clindamycin vs. clindamycin and Gentacoll

Gentacoll (Schering-Plough A/S, DK-3520 Farum, Denmark) implant is a biologically absorbable collagen with gentamicin, which enables local use of gentamicin in an abscess cavity.

PURPOSE

To increase healing rate in treatment of perianal abscess with primary suture, the effect of intraoperative parenteral clindamycin and Gentacoll was investigated against monotherapy with intraoperative clindamycin in a randomized study.

METHODS

One hundred seven patients, 55 in the Gentacoll group and 52 in the control group, were enrolled in the study and followed for three months.

RESULTS

Twelve patients (22 percent) in the Gentacoll group developed a new abscess and/or fistula. In the control group nine patients (17 percent) developed a recurrent abscess or a fistula. In both groups 43 patients had an uneventful course. The differences between the two groups were not significant. Of all 107 patients, 19.5 percent had recurrent disease in the follow-up period. Duration of hospitalization and reconvalescence were identical in both groups. One case of superficial thrombophlebitis was seen after clindamycin. No other adverse effects to either Gentacoll or clindamycin were seen.

CONCLUSION

The study shows that Gentacoll is a safe preparation but is without value as a supplement to clindamycin in the treatment of acute perianal abscess with primary suture. The study has documented the value of this treatment under cover with a intraoperative dose of clindamycin.

Gender differences in incidence of idiopathic fistula-in-ano are not explained by circulating sex hormones

The observed increased incidence of idiopathic anal fistulae in men compared with women cannot be explained by the cryptoglandular hypothesis alone. Male predilection is even more pronounced in neonates and is also seen in the canine population. Investigations into hormonal aspects of hidradenitis suppurativa suggest a possible influence of androgens in its pathogenesis. In order to investigate the possibility of a similar effect in fistula-in-ano, we have compared a range of circulating sex hormones in 15 male and 12 female patients with anal fistulae with those in equal numbers of age-matched controls. There were no differences in levels of any measured hormones between male patients and healthy controls. There was no evidence of increased androgenisation of female patients. Women with fistulae had higher levels of circulating oestradiol (253 vs 163 pmol/l, medians, P = 0.03) and lower levels of progesterone (1.05 vs 3.0 nmol/l, medians, P = 0.039) than healthy women. Further work is merited to investigate the possibility of increased local androgen conversion in anal glands.

Surgical assessment of acute anorectal sepsis is a better predictor of fistula than microbiological analysis

Twenty-two patients with acute anorectal sepsis were examined prospectively to compare surgical assessment with microbiological analysis as predictors of the aetiology of the sepsis. Culture of gut organisms was a sensitive method of detecting an underlying fistula but was not particularly specific (80 per cent). Demonstration of sepsis in the intersphincteric space in association with an anorectal abscess was 100 per cent sensitive and 100 per cent specific for detection of an underlying fistula. The demonstration was facilitated by a radially placed incision.

Results of a policy of selective immediate fistulotomy for primary anal abscess

A prospective study of a policy of selective immediate fistulotomy in the management of acute primary anal abscesses was performed. Eighty-nine patients (74%) underwent simple drainage only, as no internal openings were found during drainage of pus (group A). Thirty-one patients (26%) had drainage of pus and immediate fistulotomy (group B). Follow up for groups A and B occurred at a median of 122 weeks (104-136 weeks) and 121 weeks (104-136 weeks), respectively. No patient in group A had residual problems with anal continence whilst two patients (6.5%) from group B had minor anal incontinence following the initial procedure (p = 0.07). Ten patients from group A (11%) and four patients from group B (13%) developed recurrent anal sepsis. The overall rate of recurrent sepsis was 11.7%. In those patients who had incision and drainage alone, 90% of those who developed a recurrence and 71% of those who did not develop a recurrence grew gut-associated organisms from pus obtained during the initial drainage of the acute abscess, giving a positive predictive value for recurrence of 13.8% for a culture of gut-associated organisms. The positive predictive value for recurrent sepsis for both groups taken together for a culture of gut-associated organisms was 28.2%. Patients with acute primary anal abscess should be treated with simple drainage.

Anal fistula

Anal fistula is a common cause of chronic irritation to both patients and surgeons. Treatment failure rates may be decreased by a good appreciation of normal anorectal anatomy and fistula pathoanatomy, as well as a wide and practical knowledge of the possible treatment regimens. The various treatment options available for acute abscesses as well as simple and complex anal fistulae are presented and discussed. Identification of the patient at risk of postoperative anal incontinence or of the difficult or high fistula may allow treatment in a specialized proctology unit.

Bacteriology of anal fistulae

Anal fistulae are said to arise from cryptoglandular infection of the anal glands, which lie within the intersphincteric space. The type and virulence of the micro-organism responsible may determine whether an anal fistula develops. The microbiology of chronic anal fistulae has not been reported previously. Twenty-five consecutive anal fistulae were studied prospectively (eight intersphincteric fistulae, 12 trans-sphincteric fistulae, two suprasphincteric fistulae, one extrasphincteric fistula, one superficial fistula, one anovaginal fistula). There were 18 men and seven women, with a median age of 42 (range 22-71) years. Patients with Crohn's disease or acute anorectal suppuration were excluded. In 18 patients, 0.1 ml granulation tissue from the track of the fistula was obtained and processed within 4 h using standard microbiological techniques. Sixty-nine isolates representing at least 17 species were obtained. The predominant organisms were Escherichia coli (22 per cent), Enterococcus spp. (16 per cent) and Bacteroides fragilis (20 per cent). The majority of the growths were obtained only from enrichment. Bacteria from only one patient grew at a dilution of 10(3). Granulation tissue from 25 patients was processed for mycobacterial culture, and Mycobacterium tuberculosis was grown from one patient. No other mycobacterium was isolated. The chronic inflammation in anal fistulae does not seem to be maintained by either excessive numbers of organisms or organisms of an unusual type.

Anorectal sepsis as a presentation of occult rectal and systemic disease

Between 1980 and 1982, 233 patients were treated for anorectal sepsis in three hospitals. The incidence of underlying disease associated with perianal sepsis and the results of surgical treatment were assessed retrospectively. Of the 233 patients who had perianal sepsis, 136 (58.4 percent) had perianal abscesses, while a further 12 (5.1 percent) had associated fistulas. Ischiorectal abscesses were found in 79 (33.9 percent) and a further two (0.9 percent) had fistulas. Four (1.8 percent) patients were found to have intersphincteric abscesses. One hundred and nine (46.8 percent) had examinations under anesthesia or definitive procedures, while the remaining 124 (53.2 percent) had incision and drainage alone. A second procedure was required by 55 (23.6 percent) patients, 40 (32 percent) in the group who had incision and drainage only and 15 (14 percent) of those having initial examinations under anesthesia (P less than .001). Twenty-seven (11.6 percent) patients had occult disease. Twelve patients (5.1 percent) had systemic disease (six diabetic, three nongastrointestinal neoplasia, two inflammatory, and 1 hematologic), while of the 109 patients who had examinations under anesthesia, 15 (6.4 percent) had associated colorectal pathology (four neoplasia, 11 inflammatory). It is important that patients with anorectal sepsis have complete medical and surgical assessments at the time of their first admission.

Use of hydrogen peroxide to identify internal opening of anal fistula and perianal abscess

Hydrogen peroxide injected into a fistula or perianal abscess produces a jet of white bubbles from the internal orifice on the dentate line. This technique has been helpful in locating this often elusive ostium. Failure to produce such an efflux warns one that the pathology was different from what was expected. Confidence to abandon the search in the absence of an efflux is developing, provided the dictates of gravity are respected in positioning the patient so that the anus lies above the abscess.

Incidence of fistula-in-ano complicating anorectal sepsis: a prospective study

The incidence of fistula-in-ano following anorectal abscesses was studied prospectively in 50 consecutive patients. A total of 13 patients (26 per cent; 95 per cent confidence limits: 14-40) had a fistula diagnosed either in the acute phase or during follow-up within 6 months. Half of the fistulas diagnosed at follow-up were unrecognized by the patients and no fistulas developed in patients where culture from the abscess only revealed skin-derived bacterias. X-ray examination was of no value in the diagnosis of anal fistula.

Perirectal and perineal infections in end-stage renal disease patients

Eight patients with end-stage renal disease (ESRD) who developed bacterial infection of the perirectal area or perineum are reported. The diagnosis was not always straightforward. Bacteremia was seen in 3 of 8 patients and one of these died. Careful examination of the anus, rectum, and perineum should be mandatory in ESRD patients with undiagnosed fever. Treatment consisted of extensive surgical debridement and drainage along with antimicrobial therapy.