Correction to: Perianal Infections Update

to identify poor prognostic factors for perianal infection (PI) in patients with hemoblastosis and to define an effective tactic for preventive and therapeutic measures. The prospective study enrolled 72 patients (37 men and 35 women; mean age, 47 years) with hemoblastosis that was complicated by the development of one of the following forms of PI: abscess, infiltrate, multiple ulcers. Different clinical and laboratory characteristics of the patients were examined to identify risk factors for PI. The species-specific concordance of microorganisms isolated from the anus and blood in the development of PI was assessed to record the latter as a source of sepsis. Treatment policy was defined according to the clinical form of PI. Acute myeloid leukemias and lymphomas were the most common background diseases in 30 (41.7%) and 22 (30.6%) patients, respectively. During induction chemotherapy cycles, perianal tissue infection occurred twice more frequently (66%) than totally at the onset of hemoblastosis (13%) and after achievement of remission (during consolidation and maintenance therapy) (21%; Fisher's exact test; p=0.01). PI in agranulocytosis was more than twice as common as in its absence: 69.4% vs 30.6% (p=0.01) and was responsible for sepsis in 9 (18%) of 50 patients. The main source of perianal tissue infection in patients with granulocytopenia was anal fissures and fistulas and ulcers of the anal canal: 44 (88%) cases of the 50 cases. In PI as an abscess, the average white blood cell count was 5 times higher (p=0.01) than that in PI as an infiltrate (or multiple ulcers): 6.6·109/l and 1.2·109 g/l. Abscess formation was observed in 16 (22.2%) patients and an indication for surgical drain. The inflammatory infiltrate was found to develop in 48 (66.7%) patients; multiple ulcers were seen in 8 (11.1%); in this group, parenteral antimicrobial therapy proved to be effective in 36 (78%) patients. 29 patients were operated on for anal fissures and fistulas at intercycle intervals. After continuing CT, PI recurrences were observed in 4 (9.1%) patients. In the operated versus medically treated patients, the risk of complications associated with abnormalities in the perianal area during continued CT was 5 times statistically significantly lower (odds ratio=0.2; 95% confidence interval 0.1 to 0.5; p=0.04; Cochran-Mantel test). Induction CT cycles, the status of granulocytopenia, and the presence of infection sources in the anal canal as an anal fissure, skin ulcerations, or a fistula should be considered as independent statistically significant prognostic risk factors for PI. The number of granulocytes determines the form of inflammation, the course of infection, and the chance of developing sepsis. The effective prevention encompassing surgical treatment for anal canal diseases reduces the risk of septic complications and the number of paraproctitis recurrences, contributing to the implementation of a planned CT program in patients with hemoblastosis.

Study on five-year continuous improvement path for perianal infection prevention and control in hematopoietic stem cell transplantation Patients—Achieving zero infection through data-driven and optimized nursing schemes

Vacuum sealing is a therapeutic concept to achieve secure and rapid wound healing in traumatic soft tissue damage. Its application and effect in the treatment of severe buttocks and perianal infection are unclear.We describe a case of buttocks and perianal infection using the vacuum sealing drainage (VSD) technique. A 58-year-old man was admitted with buttocks and perianal severe infection, which was caused by injection. The size of the wounds was 40 × 30 cm. Colostomy was applied prior to the prompt surgical debridement to prevent defecation and keep the perianal region clean. Emergency debridement was then conducted. After the wounds were thoroughly washed with conventional disinfection solution, they were then covered by VSD system.The infection was controlled 9 days after the first surgery by prompt surgical debridement, the application of VSD treatment, and the use of narrow-spectrum antibiotics based on susceptibility result. After 3 applications of VSD treatment, skin grafting harvested from the left leg was conducted. All free skin grafts survived at 8 weeks. Colon was placed back into the abdominal cavity finally.Initial colostomy and debridement, the temporary VSD cover followed after several days by skin grafting is a reliable treatment regimen for severe buttocks and perianal infection.

Objective: This study aims to examine the incidence of post-chemotherapy perianal infection and its influencing factors in patients with acute leukemia.<br>Methods: A total of 243 patients with acute leukemia who underwent chemotherapy in the Three Gorges Hospital affiliated to Chongqing University, China, between January 2019 and December 2020 were selected as study subjects. In the present retrospective study, patients with post-chemotherapy perianal infection were monitored, and the perianal infection rate and clinical features of perianal infection were determined. Categorical variables were compared using the Chi-square test, and the influencing factors of post-chemotherapy perianal infection in patients with acute leukemia were evaluated using logistic analysis.<br>Results: A total of 24 patients (9.88%) with acute leukemia suffered post-chemotherapy perianal infection. Age, basic perianal disease (hemorrhoids) history, constipation, diarrhea, duration of agranulocytosis, and length of hospital stay were compared among the patients. Perianal disease classification, perianal ultrasound, colonoscopy, postoperative pathology, and other clinical data were compared and discussed in relation to the occurrence and development of the disease. The results showed that there were no significant differences in perianal infection degrees between genders and among different types of leukemia (p > 0.05). There were no statistically significant differences in age, pain score, minimum white blood cell count, deficiency duration, and length of hospital stay among patients with different degrees of infection. The Spearman rank correlation test showed that the perianal infection degree was positively correlated with the highest hypersensitive C-reactive protein (hs-CRP) level (p < 0.05). The difference was statistically significant; the higher the maximum hs-CRP/procalcitonin levels, the more serious the perianal infection.<br>Conclusions: Perianal infections are common in the procession of chemotherapy or myelosuppression. This is worthy of clinical recognition. Early recognition of perianal infection and the strengthening of infection risk factor control may be beneficial to improving the subjective feelings of patients with acute leukemia undergoing chemotherapy.

Aim. To study risk factors for relapses of perianal infection (PI) in patients with hematological tumors.
 Materials & Methods. This single-center prospective clinical trial (2016–2020) enrolled all oncohematological patients at the National Research Center for Hematology who developed PI at various stages of chemotherapy. To assess the impact of some factors on relapsing perianal infectious complications, the distribution of clinical characteristics in groups of patients with single or multiple PI episodes was analyzed.
 Results. The trial addressed 158 PI episodes in 132 patients; there were 64 men and 68 women, the median age was 40 years (range 18–77 years). PI relapses were identified in 22 (16.67 %) patients, with a higher incidence in acute myeloid leukemia (AML) patients (63.64 %). Recurrent PI episodes were usually registered on program therapy of acute leukemias (73.08 %), more often at consolidation stage (38.46 %) than at other stages of treatment (17.42 %) (hazard ratio [HR] 2.96; 95% confidence interval [95% CI] 1.19–7.35; p < 0.031). With the follow-up of 360 days from the first episode, the probability of PI relapses was 16.2 %, and it was higher in AML patients (24.3 %). In non-remission AML patients having the first PI episode, the probability of PI relapses considerably increased and accounted for 52.6 %. In case of cryptogenic pararectal abscesses, it was 20 %, if solely abscess drainage was performed at the first stage. However, no relapses were registered after the surgical treatment of pararectal fistulas. The risk factors for recurrent PI, as was shown by univariate analysis, were AML diagnosis (HR 2.94; 95% CI 1.14–7.62; p < 0.032) and the lack of remission of hematological tumor by the time of the first PI episode (HR 2.98; 95% CI 1.13–7.90; p < 0.034). By multivariate analysis, the significant risk factor was non-remission AML diagnosis by the time of the first PI episode (HR 6.94; 95% CI 2.93–16.66; p < 0.0001).
 Conclusion. The significant risk factor for PI relapses is non-remission AML diagnosis by the time of the first infectious episode. This category of patients shows the maximal probability of relapsing perianal infectious complications, which is 52.6 %. To prevent PI relapses in patients with cryptogenic pararectal abscesses, abscess drainage should be combined with scheduled surgery of anal fistulas.

In this study, we aimed to investigate the incidence, risk factors, and clinical outcomes of perianal infections during the pre-engraftment phase after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Consecutive patients who underwent non-T-cell-depleted allo-HSCT at the Peking University Institute of Hematology from January 1 to December 31, 2016 were enrolled (n = 646). Ninety-nine patients were found to have perianal infections during the pre-engraftment phase, and 80 were found to have neutropenia on perianal infection diagnosis. The cumulative incidence of perianal infection during the pre-engraftment phase after allo-HSCT was 15.3%. A history of perianal infection (hazard ratio [HR] = 15.28, p < 0.001) or hemorrhoids before allo-HSCT (HR = 3.09, p = 0.001) was significantly associated with the new occurrence of perianal infection after allo-HSCT. All patients received empirical broad-spectrum antimicrobial therapies, and 97 were cured after treatment. The clinical outcomes at 100 days after allo-HSCT were comparable in patients with and without perianal infections. In summary, patients who had perianal infection or hemorrhoids before allo-HSCT had a higher risk of new occurrence of perianal infection after allo-HSCT. With appropriate treatment, perianal infection during the pre-engraftment phase did not influence the clinical outcomes.

AIM: to present clinical variability of perianal infection (PI), developed in the debut of oncohematological disease and to determine the factors that impede PI relief and time of antitumor treatment initiation, as well as the causes of complications during chemotherapy (ChT).PATIENTS AND METHODS: the analysis included 8 patients with an infectious process in the perianal region developed in the debut of hemoblastosis and aplastic anemia (before ChT).RESULTS: in 5 of 8 patients there was a long time between start of PI and the start of ChT for hemoblastosis, from 18 to 49 days. The impediment for a favorable time to start ChT were not clarified diagnosis of hemoblastosis (acute myeloid leukemia – 2 cases, multiple myeloma – 1, lymphoma – 1) and the ongoing infectious process in patients with severe granulocytopenia (GCP). Usually undetected hematological malignancies were observed in patients with compensated data of haemogram. Complications during ChT were associated with recurrence of PI in the area of surgery (palliative drainage of anorectal abscess and fistula-in-ano) and of the sepsis with persisted inflammation in the postoperative wound on the background of GCP.CONCLUSION: PI is one of the infectious complications peculiar for the debut of oncohematological disease. Therefore, a general blood test with leukocyte formula should be performed before surgery in all patients with paraproctitis to exclude hemoblastosis. The unknown diagnosis of hemoblastosis and the ineffectiveness of surgical treatment of paraproctitis in patients with severe GCP were the main reasons for the delay in the beginning of antitumor treatment in this study. Persistent infection (fistula-in-ano) and the persistent inflammation in the wound on the background of the GCP has resulted in the recurrence of PI and sepsis during chemotherapy.

BackgroundLittle is known about the epidemiology of perianal infection in pediatric cancer patients. Objectives were to describe the characteristics, treatment and outcome of perianal infection and describe features of those with and without definite abscess in pediatric patients with acute myeloid leukemia (AML).MethodsWe performed a retrospective analysis of two multi-center cohort studies investigating risk factors for infection in children with AML. We included children with de novo AML ≤18 years of age with a perianal infections prior to the completion of AML treatment or stem cell transplantationResultsOf 235 patients with AML, 17 (7%) experienced 19 perianal infections. Median age at perianal infection was 8.2 (range 0.6–16.1) years. Local bacterial cultures were positive in 6 (32%) episodes, but none matched bacteremia isolates (n = 5). Enterobacteriacae were the most common pathogen. The 19 episodes were stratified by definite abscess (n = 12) and cellulitis/phlegmon (n = 7). All patients presented with local pain, erythema and induration or swelling. Fever was a frequent finding (n = 17, 89.4%). Among the patients with abscess, 9 (75%) were severely neutropenic at diagnosis and surgical intervention was required in 8 (42%). All patients received antibiotics; Metronidazole (n = 14) and Piperacillin/Tazobactam (n = 10) were the drugs most frequently used for treatment. Imaging was commonly performed (n = 16). Diagnostic yield was similar between computerized tomography of pelvis (5/10) and ultrasound (3/5). Severe complications occurred including fistula (n = 1), skin necrosis (n = 2) and mortality (n = 1).ConclusionPerianal infections occurred in 7% of pediatric patients with AML, with many consisting of definite abscess. Diagnostic yield were similar regardless of imaging modality and therefore, ultrasound may be considered for initial evaluation. Future research should develop consistent management approaches to perianal infection in order to improve outcomes.DisclosuresAll authors: No reported disclosures.

The efficacy of surgical intervention for perianal infection in patients with hematologic malignancies is not well established. Therefore, our study aimed to investigate the clinical efficacy and complications of surgical treatment of perianal infection in patients with hematologic malignancies. This retrospective study included patients with hematological malignancies who were diagnosed with perianal infections and treated at the China Aerospace Science & Industry Corporation 731 Hospital between 2018 and 2022. Patient characteristics, hematological data, surgical intervention, and complications, including recurrence and mortality, were analyzed. This study included 156 patients with leukemia aged 2 months to 71 years who were treated surgically for perianal infection, comprising 94 males and 62 females. Perianal infection included 36 cases of abscesses, 91 anal fistulas, and 29 anal fissures accompanied by infection. A total of 36 patients developed severe complications postoperatively, including 4 patients who died, 6 patients with severe incision bleeding, 18 patients with severe pain, 6 patients with sepsis, 12 patients who needed reoperation, 15 patients with hospitalization for more than 2 weeks, and 3 patients with anal stenosis; none of the patients developed anal incontinence. Additionally, risk factors for postoperative complications of perianal infection in patients with hematologic malignancies include leukopenia, agranulocytosis, thrombocytopenia, depth of abscess and not undergone an MRI. Surgical intervention may improve the prognosis of patients with perianal abscess formation, particularly in patients who show no improvement with medical therapy and those who develop perianal sepsis. Granulocytopenia and thrombocytopenia should be improved before surgery, which can significantly reduce postoperative complications. Although these findings are from a case series without a comparator, they may be of value to physicians because to the best of our knowledge, no randomized or prospective studies have been conducted on the management of perianal infections in patients with hematological malignancies.

AIM : to study the perianal infection (PI) in patients with granulocytopaenia (GCP) and hematological malignancies (HM). PATIENTS AND METHODS: the prospective study (2016-1018) includes 95 episodes of PI in 76 patients with HM (male/female 35/44; mean age of 35 (17-69)). 43(54.4%) of the patients were detected to develop acute leukemia (AML – 34 (43%); ALL – 9(11.4%); NHL – 17(21.5%). The comparison of PI episodes within the GCP period (number of granulocytes less than 0.5x10 9 /l) and without it was done. RESULTS: PI episodes within the period of GCP were significantly much more often than those without GCP (77.9% vs 22.1%, relative risk 3.5 (95% CI: 2.4-5.2). The biggest number of PI episodes in the setting of GCP was registered within the period of chemotherapy (ChT): in the phase of consolidation (28.4%) and induction (13.3%) of acute leukemia ChT and lymphomas’ ChT (20.3%). Anal fissures were the most frequent source of PI within GCP period (66.2% vs 19.1% without GCP, p&lt;0.001). Inflammatory changes in perianal tissues were clinical features of PI in the setting of GCP in 89.2% of the cases: inflammatory mass in 71.6% (vs 23.8% without GCP, p&lt;0.001), abscess in 8.1% (vs 66.7% without GCP, p&lt;0.001). In 10.8% of the cases of PI with GCP only perianal pain and fever were registered. No tissues change was detected with the lowest WBC count (Me 0.2 (0.1-0.5) x10 9 /l). Bloodstream infections were detected in 15 (20.3%) episodes within the period of GCP only, of them in 6 (8.1%) cases the species matching of microorganisms in blood and in rectum was noticed. Within the period of GCP antibacterial therapy was carried out in 98.6% of the cases: antibacterial therapy alone was applied in 87.8% of the episodes (vs 7.2% without GCP, p&lt;0.001); both antibacterial therapy and surgical treatment were carried out in 10.8% (vs 61.9% without GCP, p&lt;0.001) of the cases. Mean duration of antibiotic treatment of patients with GCP was drastically longer in the group of postoperative patients in comparison with the group of those who had conservative treatment (25.5 vs 15.1 days, p=0.05). Antimicrobial therapy within GCP period resulted into inflammation regress in 83.1% of the cases; abscess or fistula formation, hence surgical treatment in 13.8% of the cases; progression of infection in 3.1% of the cases. Increase of GCP duration up to 30 and more days is connected with bacteremia rate increase (12.5% vs 28%, p&lt;0.05); combinations of PI with other infections (25% vs 52%, p&lt;0.05); requirement of antimicrobial therapy modification (16.7% vs 40%, p&lt;0.05). CONCLUSION: GCP significantly raises risk of PI. PI that develops in the setting of GCP, is characterized by abnormal, often low clinical manifestations and high risk of sepsis. Invasion of microorganisms through affected tissue seals is the basic mechanism of perianalinfection within the period of GCP. Antibacterial therapy is the prior method of PI treatment in the settings of GCP; antibacterial therapy efficiency is 83.1%. Need for surgery in the period of GCP is associated with the infectious episode and antibacterial therapy duration increase. Lengthening of GCP is a negative predictor in PI treatment.

ObjectivesPerianal infection is a serious complication in patients undergoing chemotherapy for haematological malignancies. Therefore, we aimed to develop a predictive model to help medical staff promptly screen patients at a...

Bone marrow transplantation (BMT) is often associated with profound neutropenia. Allogeneic transplant recipients also have defects in both humoral and cellular immunity and thus are subject to increased risk of serious, often life-threatening, infection even beyond the period of granulocyte recovery. The current study was undertaken to evaluate patients who required operative intervention for perianal sepsis following BMT. The bone marrow transplant database at a single institution was used to identify all patients diagnosed with perianal infections after autologous or allogeneic BMT. Charts were reviewed in a retrospective manner. Over a ten-year period ending in November 1993, 963 BMT were performed at the City of Hope National Medical Center. Twenty-four patients were diagnosed with perianal infections following their transplants. Fifteen patients did not have purulent collections requiring drainage and were treated with antibiotics and supportive measures alone. Nine patients (37.5 percent) required surgical intervention between 10 and 380 days following transplantation. At the time of surgical intervention, seven patients had purulent collections and two patients had acute and chronic inflammation, tissue necrosis, and fibrosis. Of the two patients with an absolute neutrophil count less than 1,000, a purulent collection was found in one of the patients. Cultures taken from perianal abscesses were almost all polymicrobial, and the most common organisms were Escherichia coli, Bacteroides, Enterococcus, and Klebsiella. For those patients undergoing surgical intervention, mean time to complete wound closure by secondary intention was 37.6 days; five patients healed in less than 15 days, two patients healed at 93 and 114 days, and two patients had persistent, open wounds at time of death, which was unrelated to their perianal disease. Five patients were receiving systemic steroids at time of surgical intervention; this did not appear to affect time to wound healing. Perianal infections are a rare complication of BMT. Majority of these infections are polymicrobial, and organisms isolated are similar to those seen in the perianal infections of nonimmunosuppressed patients. Despite steroid use, granulocytopenia does not exclude the possible presence of purulent collections, and clinical examination should guide the decision for surgical drainage. In general, perianal wound healing is not prolonged in BMT patients.

e19016 Background: Perianal infection is a rare and poorly understood complication of patients with acute myeloid/lymphocytic leukemia (AML/ALL). With the advancements in oncology, patients are living longer in an immunocompromised state and thus bearing the inherent problems such as infections that arise with it. Perianal infection and its management impacts patients' quality of life as well as interrupts their ongoing oncologic treatment. The optimal treatment strategy for perianal infections in this highly immunocompromised group remains unclear, as does the selection and outcomes of patients for operative intervention. The aim of this study is to identify patient characteristics associated with perianal infection and to delineate outcomes in patients that undergo operative intervention. Methods: The National Inpatient Sample (NIS) database was used to identify hospitalized patients with diagnoses of perianal abscess and AML/ALL between 2007 and 2015. Patient data were weighted to obtain national estimates. Demographics and clinical characteristics were compared between patients with and without perianal disease using Rao-Scott Chi-square test for categorical variables, and weighted simple linear regression for continuous variables. Characteristics and outcomes were compared between patients who underwent operative or non-operative management. Results: There were 12,626 (0.7%) patients with perianal disease among 1,782,778 AML/ALL patient admissions. Patients with perianal disease were more likely to be younger (43.9 (42.5 – 45.3) years, p &lt; 0.001), male (67.4% vs 32.6%, p &lt; 0.001) and white (65.8% vs 54.8%, p &lt; 0.001). Length of stay (18.4 days vs 9 days, p &lt; 0.001) and hospital cost ($54K vs $25K, p &lt; 0.001) were higher in those with perianal disease, but there was no difference in in-hospital mortality (5.5% in those with perianal diseases vs 6.2% in those without, p = 0.150). Greater proportion of patients without perianal disease were discharged to hospice (12.6% patients without perianal disease vs 5.1% patients with perianal disease, p &lt; 0.001). Receiving a surgical intervention did not improve outcomes with respect to in-hospital mortality (5.9% operative vs 5.4 non-operative, p = 0.596), length of stay (20.2 days vs 18.2 days, p = 0.582) or hospital cost ($67K vs $53K, p = 0.525). Conclusions: Perianal disease is a rare but distressing complication in AML/ALL patients associated with longer hospital stays and higher hospital costs. Operative intervention for perianal disease did not reduce rates of in-hospital mortality, length of stay or hospital cost but it does impact the probability of discharge to hospice. Non-operative and operative intervention both remain equivocal in changing the outcomes these patients. Further studies are required to examine these associations and determine best practices for treatment of this condition in this complex patient population.

BackgroundPerianal infection is a common problem for patients with acute leukemia. However, neutropenia and bleeding tendency are relatively contraindicated to surgical intervention. The epidemiology, microbiology, clinical manifestations and outcomes of perianal infection in leukemic patients are also rarely discussed.MethodThe medical records of 1102 adult patients with acute leukemia at a tertiary medical center in Taiwan between 2001 and 2010 were retrospectively reviewed and analyzed.ResultThe prevalence of perianal infection was 6.7% (74 of 1102) in adult patients with acute leukemia. Twenty-three (31%) of the 74 patients had recurrent episodes of perianal infections. Patients with acute myeloid leukemia had higher recurrent rates than acute lymphoblastic leukemia patients (p = 0.028). More than half (n = 61, 53%) of the perianal infections were caused by gram-negative bacilli, followed by gram-positive cocci (n = 36, 31%), anaerobes (n = 18, 15%) and Candida (n = 1, 1%) from pus culture. Eighteen patients experienced bacteremia (n = 24) or candidemia (n = 1). Overall 41 (68%) of 60 patients had polymicrobial infection. Escherichia coli (25%) was the most common micro-organism isolated, followed by Enterococcus species (22%), Klebsiella pneumoniae (13%), and Bacteroides species (11%). Twenty-five (34%) of 74 patients received surgical intervention. Acute leukemia patients with surgically managed anal fistulas tended to have fewer recurrences (p = 0.067). Four (5%) patients died within 30 days after diagnosis of perianal infection. Univariate analysis of 30-day survival revealed the elderly (≧ 65 years) (p = 0.015) and patients with shock (p<0.001) had worse outcome. Multivariate analysis showed septic shock to be the independent predictive factor of 30-day crude mortality of perianal infections (p = 0.016).ConclusionPerianal infections were common and had high recurrence rate in adult patients with acute leukemia. Empirical broad-spectrum antibiotics with anaerobic coverage should be considered. Shock independently predicted 30-day crude mortality. Surgical intervention for perianal infection remains challenging in patients with acute leukemia.

Introduction. Perianal infection (PI) in patients with hematological malignancies is characterized by a wide spectrum of pathogens and a variety of clinical manifestations and mechanisms of development of the infectious process.Aim: to study the pathogenetic mechanisms of PI development in patients with hematological malignancies and to develop prevention tactics.Materials and methods. The prospective study included 132 patients with hematological malignancies who had episodes of PI. The infectious process in the pararectal fi ber was registered based on the data of clinical examination or magnetic resonance imaging. Sources of infection and microbiologic results were studied.Results: Two main mechanisms of PI development were revealed, the frequency of which was statistically significantly different depending on the presence of neutropenia (p &lt; 0.0001, odds ratio (OR) = 24.42 (confidence interval (CI) 95% [9.82–60.74]). In PI episodes that developed against the background of neutropenia, the predominant mechanism of infection was the penetration of microorganisms through broken tissue barriers (75 %): anal fissures were the entry gate of infection in 62.9 % of episodes; perianal ulcers and skin erosions — in 12.1 %. The alternative route of infection (cryptogladular mechanism) was registered in the majority of patients without neutropenia (66.7 %) and was represented by the involvement of crypts of the anal canal (28.6 %) or the presence of pararectal fistulas (38.1 %). Clinical manifestations of PI were associated with leukocyte count (p &lt; 0.0001) and mechanism of infection (p &lt; 0.0001). The median leukocyte count in patients with abscesses (2.12×109 /L) was statistically significantly higher than in infiltrates (0.57×109 /L) and necrosis (0.74×109 /L). The main source of infection in infiltrates was anal fissures (70.4 %), while in abscesses the main sources of infection were crypts of the anal canal (39 %) and pararectal fistulas (36 %). The main causative agents of PI were Gram-negative bacteria (Escherichia coli (43 %), Klebsiella spp. (15 %), Pseudomonas aeruginosa (4.4 %)), and Enterococci (12.5 %). P. aeruginosa was isolated more often in necrosis (22 %) than in other clinical forms of PI (3–5 %) (p = 0.0033), while the frequency of detection of other bacteria was independent of the clinical manifestations of PI. PI was a microbiologically proven source of sepsis in 9.5 % of PI episodes. The probability of PI-associated bloodstream infections was highest at 5 days and was significantly higher in patients with neutropenia (10 % vs 2 %) (p = 0.0044).Conclusion: Different mechanisms of pararectal cell infection should be taken into account when forming a strategy for the prevention of PI.