Pus Samples in Complicated Appendicitis: An Important Investigation or a Waste of Resources: A Prospective Cohort Study

Perforated Appendicitis in Children: Management, Microbiology, and Antibiotic Stewardship

Although appendicitis has been described for more than 300 years, its optimal management remains a topic of active investigation. Acute appendicitis is the most common cause of peritonitis in children, and rates of perforated appendicitis are much higher in children than in adults. Increased risk for perforated appendicitis in children is related to a delay in diagnosis due to age, size, access to care, and more. Surgical options include immediate appendectomy versus nonoperative management with intravenous antibiotics ± a drainage procedure, with a subsequent interval appendectomy. Microbiota of perforated appendicitis in children most often includes Escherichia coli, Bacteroides fragilis, Streptococcus, and more. Even though the most common organisms are known, there is a large variety of practice when it comes to postoperative antibiotic management in these patients. Studies discuss the benefits of mono- versus dual or triple therapy without a particular consensus regarding what to use. This is reflected across differing practices at various institutions. In this review, we aim to explore the implications of perforated appendicitis in pediatrics, common organisms seen, antibiotic regimen coverage, and the implications of variations of practice. Resistance to commonly used broad-spectrum antibiotics is evolving, therefore minimization of care variability is needed for improved patient outcomes and proper antibiotic stewardship.

An Update on Acute Appendicitis in Lebanon: Insights From a Single-Center Retrospective Study

Background Acute appendicitis is the most common surgical emergency worldwide with scarce reports about its prevalence in the Middle East. To date, no epidemiological article has described the incidence of appendicitis in Lebanon. Our primary objective was to estimate the rate of appendicitis in a single center in Lebanon. Our secondary objectives included identifying differences between simple and complicated appendicitis regarding demographics, pre and postoperative characteristics, and symptoms and signs of appendicitis. Methodology A retrospective study was conducted at a single central university hospital in Lebanon. Patients with a clear diagnosis of acute appendicitis were included. Pregnant women, lactating women, patients with organ dysfunction, and patients younger than 18 years old or older than 80 years old were excluded. We reviewed and collected the data of patients who presented to the hospital between November 2018 and November 2019 and November 2020 and November 2021. Results A total of 95 patients were included in our study, with 35 women and 60 men. The mean body mass index of patients with simple appendicitis was 19.14 ± 9.66 kg/m² compared to 18.97 ± 10.37 kg/m² in patients with complicated appendicitis (p = 0.94). A total of 42.3% of patients who used antibiotics 24 hours after the operation had simple appendicitis, whereas 20.8% had complicated appendicitis (p = 0.004). Conclusions Antibiotic usage and the length of hospital stay were correlated with the severity of appendicitis, as reported in the literature. Further randomized studies with a larger number of patients and covering several hospitals in Lebanon are warranted.

Do Cultures From Percutaneously Drained Intra-abdominal Abscesses Change Treatment? A Retrospective Review

BACKGROUND

Routinely obtaining intraoperative cultures for abdominal infections is not a currently recommended evidence-based practice. Yet, cultures are frequently sent from these infections when they are managed by image-guided percutaneous drains.

OBJECTIVE

This study aimed to determine the utility of cultures from percutaneously drained intra-abdominal abscesses.

DESIGN

Retrospective medical record review.

SETTING

Single university-affiliated institution.

PATIENTS

Inpatients with an intra-abdominal abscess secondary to diverticulitis or appendicitis between 2013 and 2021 managed with image-guided percutaneous drain, excluding those with active chemotherapy, HIV, or solid organ transplant, were included in the study.

MAIN OUTCOME MEASURES

Frequency culture data from percutaneous drains changed antimicrobial therapy.

RESULTS

There were 221 patients who met the inclusion criteria. Of these, 56% were admitted for diverticulitis and 44% for appendicitis. Patients were 54% female and had a median age of 62 years (range, 18-93), and 14% were active smokers. The median length of hospitalization was 8 days (range, 1-78) and the median antibiotics course was 8 days (range, 1-22). Culture data from percutaneous drains altered antimicrobial therapy in 8% of patients (16/211). A culture was obtained from 95% of drains, with 78% of cultures with growth. Cultures grew multiple bacteria in 66% and mixed variety without speciation in 13%. The most common pathogen was the Bacteroides family at 33% of all bacteria. The most common empiric antibiotic regimens were ceftriaxone used in 33% of patients and metronidazole used in 40% of patients. Female sex ( p = 0.027) and presence of bacteria with any antibiotic resistance ( p < 0.01) were associated with higher likelihood of cultures influencing antimicrobial therapy.

LIMITATIONS

Retrospective and single institution's microbiome.

CONCLUSIONS

Microbiology data from image-guided percutaneous drains of abdominal abscesses altered antimicrobial therapy in 8% of patients, which is lower than reported in previously published literature on cultures obtained surgically. Given this low rate, similar to the recommendation regarding cultures obtained intraoperatively, routinely culturing material from drains placed in abdominal abscesses is not recommended. See Video Abstract at http://links.lww.com/DCR/C64 .

LOS CULTIVOS DE ABSCESOS INTRA ABDOMINALES DRENADOS PERCUTNEAMENTE CAMBIAN EL TRATAMIENTO UNA REVISIN RETROSPECTIVA

ANTECEDENTES:La obtención rutinaria de cultivos intra-operatorios para infecciones abdominales no es una práctica basada en evidencia actualmente recomendada. Sin embargo, con frecuencia se envían cultivos de estas infecciones cuando se manejan con drenajes percutáneos guiados por imágenes.OBJETIVO:Determinar la utilidad de los cultivos de abscesos intra-abdominales drenados percutáneamente.DISEÑO:Revisión retrospectiva de gráficos.ESCENARIO:Institución única afiliada a la universidad.PACIENTES:Pacientes hospitalizados con absceso intra-abdominal secundario a diverticulitis o apendicitis entre 2013 y 2021 manejados con drenaje percutáneo guiado por imagen, excluyendo aquellos con quimioterapia activa, VIH o trasplante de órgano sólido.PRINCIPALES MEDIDAS DE RESULTADO:Los datos de cultivo de frecuencia de los drenajes percutáneos cambiaron la terapia antimicrobiana.RESULTADOS:Hubo 221 pacientes que cumplieron con los criterios de inclusión. De estos, el 56% ingresaron por diverticulitis y el 44% por apendicitis. El 54% de los pacientes eran mujeres, tenían una edad media de 62 años (18-93) y el 14% eran fumadores activos. La duración de hospitalización media fue de 8 días (rango, 1-78) y la mediana del curso de antibióticos fue de 8 días (rango, 1-22). Los datos de cultivo de drenajes percutáneos alteraron la terapia antimicrobiana en el 7% (16/221) de los pacientes. Se obtuvo cultivo del 95% de los drenajes, con un 79% de cultivos con crecimiento. Los cultivos produjeron múltiples bacterias en el 63% y variedad mixta sin especiación en el 13%. El patógeno más común fue la familia Bacteroides con un 33% de todas las bacterias. El régimen de antibiótico empírico más común fue ceftriaxona y metronidazol, utilizados en el 33% y el 40% de los pacientes, respectivamente. El sexo femenino ( p = 0,027) y la presencia de bacterias con alguna resistencia a los antibióticos ( p < 0,01) se asociaron con una mayor probabilidad de que los cultivos influyeran en la terapia antimicrobiana.LIMITACIONES:Microbioma retrospectivo y de una sola institución.CONCLUSIONES:Los datos microbiológicos de los drenajes percutáneos guiados por imágenes de los abscesos abdominales alteraron la terapia antimicrobiana en el 7% de los pacientes, que es inferior a la literatura publicada previamente sobre cultivos obtenidos quirúrgicamente. Dada esta baja tasa, similar a la recomendación sobre cultivos obtenidos intraoperatoriamente, no se recomienda el cultivo rutinario de material de drenajes colocados en abscesos abdominales. Consulte Video Resumen en http://links.lww.com/DCR/C64 . (Traducción-Dr. Mauricio Santamaria.

Using Microbiology Culture in Pediatric Appendicitis to Risk Stratify Patients: A Cohort Study

Background: We sought to investigate the value of intra-operative microbiology samples in pediatric appendicitis. Proposed benefits include tailoring post-operative antimicrobial management, risk-stratifying patients, and reducing post-operative intra-abdominal abscess formation. Patients and Methods: All cases of appendicitis managed with appendicectomy in a single center were collected from January 2015 to August 2020. Intra-operative microbiology samples were taken routinely. Post-operative outcomes were analyzed with reference to culture and sensitivity results. Histologic findings were further categorized as normal, simple, or complex. Results: Six hundred seventy-eight children had appendicectomies, and 608 had both microbiology and histology samples taken. Intra-abdominal fluid collection and subsequent intervention rates were 22% and 9%, respectively. There were more collections in those with a culture positive result (p < 0.001), and those growing each of three recognized organisms, Escherichia coli (p < 0.001), Pseudomonas aeruginosa (p = 0.01), and Streptococcus anginosus group (p < 0.001). Intervention rate was higher in the culture-positive result group (p = 0.002) and the Streptococcus anginosus group (p < 0.001). Conclusions: This study shows an increased risk of developing a collection with the isolation of one of three key organisms (Escherichia coli, Pseudomonas aeruginosa, Streptococcus anginosus group). Sersoal swabs are an effective and practical method of gathering information on organisms. Microbiologic yield was correlated to the severity of appendicitis. Isolation of Streptococcus anginosus increases the incidence of collections to 50%. This is useful to empower surgeons to prognosticate patients' potential outcomes based on both intra-operative, and microbiologic findings, and is useful in counseling patients and managing expectations. A prolonged course of antibiotic agents or higher dose may mitigate this risk.

Implications of bacteriological study in complicated and uncomplicated acute appendicitis

Purpose

Bacteriological sample in the presence of intraabdominal free fluid is necessary to adapt the antibiotherapy and to prevent the development of resistance. The aim was to evaluate the differences between uncomplicated (UAA) and complicated acute appendicitis (CAA) in terms of bacterial culture results and antibiotic resistance, and to evaluate the factors linked with CAA.

Methods

We performed a single-center, retrospective observational study of all consecutive patients who presented with appendicular peritonitis and underwent emergent surgery in a tertiary referral hospital in Brussels, Belgium, between January 2013 and December 2020. The medical history, parameters at admission, bacterial culture, antibiotic resistance, and postoperative outcomes of 268 patients were analyzed. UAA was considered catarrhal or phlegmonous inflammation of the appendix. CAA was considered gangrenous or perforated appendicitis.

Results

Positive microbiological cultures were significantly higher in the CAA group (68.2% vs. 53.4%). The most frequently isolated bacteria in UAA and CAA cultures were Escherichia coli (37.9% and 48.6%). Most observed resistances were against ampicillin (28.9% and 21.7%) and amoxicillin/clavulanic acid (16.4% and 10.5%) in UAA and CAA, respectively. A higher Charlson comorbidity index, an elevated white blood cell count, an open procedure, and the need for drainage were linked to CAA. Culture results, group of bacterial isolation, and most common isolated bacteria were not related to CAA.

Conclusion

CAA presented a higher rate of positive cultures with increased identification of gram-negative bacteria. Bacterial culture from the peritoneal liquid does not reveal relevant differences in terms of antibiotic resistance.

[The importance of microbiological results for the treatment of complicated appendicitis-a monocentric case-control study]

BACKGROUND

Patients with complicated appendicitis frequently develop postoperative septic complications. There are no uniform standards for the choice of perioperative antibiotic prophylaxis and the duration of postoperative antibiotic treatment. The purpose of this study was to investigate associations between microbiological samples and postoperative complications.

METHODS

Patients with appendectomy and positive intraoperative swabs during 2013-2018 were included in this case-control study. Pathogen classes and their resistance patterns were evaluated in initial and follow-up swabs and compared in each of the groups with and without complications.

RESULTS

A total of 870 patients underwent surgery during the period studied. Pathogen detection succeeded in 102 of 210 cases (48.6%) with suspected bacterial peritoneal contamination. Conversion from laparoscopic to open intra-abdominal perforation and the presence of an abscess were independent risk factors for wound infections in the multivariate analysis. The combination of different classes of pathogens resulted in significantly increased overall resistance to ampicillin/sulbactam in both the initial swabs (57%) and the follow-up swabs (73%). Resistant E. coli strains combined with certain anaerobes were also regularly detected in postoperative intra-abdominal abscesses. Piperacillin/tazobactam was effective against 83% of positive swabs in our resistance tests.

CONCLUSION

Surgical treatment for complicated appendicitis remains the central therapeutic column. A regular review of the existing resistance patterns in perforated appendicitis can help to adjust and improve antibiotic treatment. Piperacillin/tazobactam should be used cautiously as a reserve antibiotic. A valid alternative is second or third generation cephalosporins in combination with metronidazole.

A Retrospective Comparative Study Assessing Patients With Acute Appendicitis During the Pre and Through Lebanese Financial Crisis

Introduction

In the past three years, Lebanon, a country located in the Middle East, has faced a severe financial crisis. This crisis had many effects on several sectors in Lebanon, including the healthcare sector. The authors expected an increase in the rate of complicated appendicitis after the crisis due to the shortage of medical supplies. The aim of the study was to compare the rate of complicated acute appendicitis before and after the Lebanese crisis.

Methods

The study included two groups of patients with acute appendicitis. The first group included patients admitted in the period between November 2018 and November 2019 (before the crisis). The second group included patients admitted between November 2020 and November 2021 (during the crisis). The data were collected retrospectively and analyzed using SPSS software (version 25.00) (SPSS Inc., Chicago, IL). Ethical approval was obtained and the study was registered at Al Zahraa hospital, University Medical Center in Beirut, Lebanon.

Results

The study included 49 patients in the first group (before the crisis) and 46 patients in the second group (after the crisis). The percentage of complicated appendicitis has increased from 22.4% before the crisis to 28.3% during the crisis. The study showed a statistically significant difference between the two groups in the white blood cell count (10,831 versus 7180 cu.mm, respectively, p=0.006), the operating time (59.9 versus 79.0 minutes, respectively; p=0.004), the need to obtain an intra-peritoneal swab for bacterial culture (83.7% versus 58.7%, respectively; p=0.007), and the need for intra-abdominal abscess drainage (6.1% versus 28.3%, respectively; p=0.004). There were no significant differences in the demographics, the duration of postoperative antibiotic use, the duration of stay in the hospital, and the postoperative complications in the first month following surgery.

Conclusion

Due to the decreased financial income, the high cost of medical care during the Lebanese crisis, and the delay of patients’ presentation to the hospital, the rate of complicated appendicitis increased during the crisis.

Are We Hitting the Target?: The Effectiveness of Distinct Antibiotic Regimens in Pediatric Appendectomies

BACKGROUND

Currently, a range of different antibiotics are administered perioperatively during appendectomy surgery in the pediatric population. One reason for the lack of a uniform treatment regimen is the paucity of large studies on microbiologic data and susceptibility patterns.

METHODS

A retrospective, monocentric study on antibiotic susceptibility, including 1258 pediatric patients undergoing appendectomy from 2012 to 2020 was performed. Predictors for prolonged length of stay (LOS) and complications were determined using regression analysis, and objective criteria for broad-spectrum antibiotic regimens were identified. Simulations of the effectiveness of different antibiotic regimens against identified bacterial susceptibility results were conducted.

RESULTS

The most important predictors for prolonged LOS and an increased incidence of infectious complications are elevated preoperative C-reactive protein levels, high intraoperative severity gradings and insufficient primary antibiotic treatment. Based on our results, a simple antibiotic treatment, consisting of cefuroxime-metronidazole (C-M) or ampicillin-sulbactam (AS), is sufficient in around 85% of all patients; both options being equally efficient. In severe appendicitis, the likelihood of resistance is 31% and 32% for C-M and AS, respectively. For piperacillin-tazobactam and C-M-tobramycin, the incidence of bacterial resistance decreases to 12%. Resistance is reduced to 8% for AS-tobramycin treatment. The patient populations benefiting most from an extended antibiotic regimen are those with a high intraoperative severity grading.

CONCLUSIONS

Evidence suggests that an insufficient antibiotic regimen is associated with a prolonged LOS and a higher rate of infectious complications, justifying the expansion of a simple antibiotic regimen in cases of severe intraabdominal findings. In all other cases, a simple antibiotic treatment with AS is recommended.

Management and Microbiology of Perforated Appendicitis in Pediatric Patients: A 5-Year Retrospective Study

INTRODUCTION

This study aims to assess the current epidemiology and microbiology of perforated appendicitis, how antibiotic choice and duration correlate with meaningful clinical outcomes, and whether serial white blood cell (WBC) counts provide clinical value.

METHODS

Five-year retrospective cohort study, 2015-2019, among 333 consecutive children, ages 0-18 years, treated at St. Louis Children's Hospital for perforated appendicitis. Main outcomes included length of stay (LOS), postoperative abscess formation, and readmission. Statistical analysis was performed with uni- and multi-variate analyses.

RESULTS

Intra-abdominal cultures most commonly grew Bacteroides fragilis (52%) and Escherichia coli (50%). Patients who initially received broad-spectrum antibiotics (meropenem, piperacillin-tazobactam, fourth-generation cephalosporins) for perforated appendicitis had greater rates of postoperative abscess formation (25% vs. 12%, p < 0.01) and LOS (7.0 vs. 5.7 days, p < 0.01). Similarly, antibiotics at time of discharge were associated with greater postoperative abscess formation (22% vs. 9%, p < 0.01) and LOS (6.4 vs. 5.6 days, p = 0.02). However, discharge with strictly oral antibiotics was not correlated with greater LOS, postoperative abscess formation, or readmission rates compared to discharge without antibiotics. Serial WBC counts had no predictive value for LOS, postoperative abscess formation, or readmission.

CONCLUSIONS

Bacteroides fragilis and E. coli were the most common intra-abdominal microbes for perforated appendicitis among our cohort. In non-critically ill children, the routine use of broad-spectrum antibiotics or continuation of antibiotics beyond discharge was not correlated with improved clinical outcomes. Additionally, WBC counts were not correlated with meaningful clinical outcomes.

Case report: appendicitis induced Staphylococcus aureus and Klebsiella pneumoniae bacteremia in a young healthy male

Background

Appendicitis is one of the most frequently encountered conditions at the emergency department. Distinction is made between complicated and uncomplicated appendicitis. Complicated appendicitis may cause serious intra-abdominal infection, bacteremia, or sepsis. Emergency health providers should be highly alert to any early signs indicating such complications.

Case presentation

We present the case of a healthy young male with a gangrenous appendicitis, who received antibiotics and underwent appendectomy. Blood cultures showed unequivocal Staphylococcus aureus and concomitant Klebsiella pneumoniae bacteremia requiring prolonged antibiotic treatment and further diagnostic evaluation.

Conclusions

Although rare, appendicitis can cause Staphylococcus aureus and Klebsiella pneumoniae bacteremia with extensive implications for workup and antibiotic management. Our case stresses the importance of obtaining cultures in patients with suspicion of bacteremia given its consequences for clinical management.

The intraperitoneal bacteriology and antimicrobial resistance in acute appendicitis among children: a retrospective cohort study between the years 2007-2017

This study aims to describe the microbiology and susceptibility profile of the intraperitoneal flora in complicated appendicitis. It is a retrospective cohort study including children < 18-year-old with pathologically confirmed appendicitis, from 2007 to 2017. It included 1466 children. Intraperitoneal samples were obtained from 655 (44.7%) patients, and 201 (30.7%) had positive culture with 395 pathogens. Gram-negative rods comprised 67.6%, Gram-positive cocci 21.5%, and anaerobes 10.9% of the isolates. Gram-positive cocci were detected in 67 (37.8%) patients. Milleri group Streptococci was the most frequently isolated Gram-positive (44.7%). The proportional rate of Milleri group Streptococci from Gram-positive cocci increased from 9.5 to 56.3% (P < 0.001, OR 12.214). Patients with Gram-positive cocci had longer hospital stay (mean 9.36 + 6.385 vs 7.72 + 4.582, P = 0.036, (CI -3.165, -0.105)) and more complicated disease (89.5% vs 78.4%, P = 0.045, OR 2.342). Patients with Milleri group Streptococci isolates readmitted more frequently (26.5% vs 13.2%, P = 0.05, OR 2.37). Resistance to amoxicillin-clavulanate, gentamicin, ceftazidime, piperacillin-tazobactam, and amikacin were detected in 29.1%, 6.5%, 2.3%, 1.2%, and 0.7% of the Gram-negative rods, respectively.Conclusion: The rates of Gram-positive cocci and particularly Milleri group Streptococci in peritoneal fluid are increasing. More complicated disease and longer hospital stay in Gram-positive cocci and higher readmission rate in Milleri group Streptococci. These emphasize the role of anti-Gram-positive antimicrobials. What is known: • Gram-negative rods are the main isolates in complicated appendicitis. • The choice of antibiotic regimen is an unsettled issue due to resistance. What is new: • Increased rate of Gram-positive cocci and Milleri group Streptococci. • More complicated disease, longer hospital stay, and higher readmission rate.

[Recommendations on treatment of acute appendicitis : Recommendations of an expert group based on the current literature]

The paradigm shift in the treatment concept for acute appendicitis is currently the subject of intensive discussions. The diagnosis and differentiation of an uncomplicated from a complicated appendicitis as well as the selection of an adequate treatment is very challenging, especially since nonoperative treatment models have been published. The laparoscopic appendectomy is still the standard for most cases. Guidelines for the treatment of acute appendicitis do not exist in Germany. Therefore, a group of experts elaborated 21 recommendations on the treatment of acute appendicitis after 3 meetings. After initial definition of population, intervention, comparison and outcome (PICO) questions, recommendations have been finalized through the Delphi voting system. The results were evaluated according to the current literature. The aim of this initiative was to define a basic support for decision making in the clinical routine for treatment of acute appendicitis.

Routine Intraoperative Bacterial Culture May Be Needed in Complicated Appendicitis

Purpose

Choosing the appropriate antibiotic is important for treatment of complicated appendicitis. However, increasing multidrug resistant bacteria have been a serious problem for successful treatment. This study was designed to identify bacteria isolated from patients with complicated appendicitis and reveal their susceptibilities for antibiotics and their relationship with patient clinical course.

Methods

This study included patients diagnosed with complicated appendicitis and examined the bacterial cultures and antimicrobial susceptibilities of the isolates. Data were retrospectively collected from medical records of Kangbuk Samsung Hospital from January 2008 to February 2018.

Results

The common bacterial species cultured in complicated appendicitis were as follows: Escherichia coli (n=113, 48.9%), Streptococcus spp. (n=29, 12.6%), Pseudomonas spp. (n=23, 10.0%), Bacteriodes spp. (n=22, 9.5%), Klebsiella (n=11, 4.8%), and Enterococcus spp. (n=8, 3.5%). In antibiotics susceptibility testing, the positive rate of extended-spectrum beta lactamase (ESBL) was 9.1% (21 of 231). The resistance rate to carbapenem was 1.7% (4 of 231), while that to vancomycin was 0.4% (1 of 231). E. coli was 16.8% ESBL positive (19 of 113) and had 22.1% and 19.5% resistance rates to cefotaxime and ceftazidime, respectively. Inappropriate empirical antibiotic treatment (IEAT) occurred in 55 cases (31.8%) and was significantly related with organ/space surgical site infection (SSI) (7 of 55, P=0.005).

Conclusion

The rate of antibiotic resistance organisms was high in community-acquired complicated appendicitis in Koreans. Additionally, IEAT in complicated appendicitis may lead to increased rates of SSI. Routine intraoperative culture in patients with complicated appendicitis may be an effective strategy for appropriate antibiotic regimen.

Intraoperative cultures during appendectomy in children are poor predictors of pathogens and resistance patterns in cultures from postoperative abscesses

BACKGROUND

Intraoperative cultures are commonly sent in complicated appendicitis. Culture-guided antibiotics used to prevent postoperative infectious complications are debated. In this study, we describe the microbial overlap between intraoperative and abscess cultures, and antibiotic resistance patterns.

METHOD

A local register of a children's hospital treating children 0-15 years old with appendicitis between 2006 and 2013 was used to find cases with intraoperative cultures, and cultures from drained or aspirated postoperative intraabdominal abscesses. Culture results, administered antibiotics, their nominal coverage of the identified microorganisms, and rationales given for changes in antibiotic regimens were collected from electronic medical records.

RESULTS

In 25 of 35 patients who met inclusion criteria, there was no overlap between the intraoperative and abscess cultures. In 33 of 35 patients, all identified intraoperative organisms were covered with postoperative antibiotics. In 14 patients, organisms in the abscess culture were not covered by administered antibiotics. Enterococci not found in the intraoperative culture were found in 12 of 35 abscesses. We found no difference in the antibiotic coverage between rationales given for antibiotic changes.

CONCLUSION

The overlap between intraoperative cultures and cultures from subsequent abscesses was small. Lack of antibiotic coverage of intraoperative cultures was not an important factor in abscess formation.