Abscesses in different body sites among children: a single-center prospective study

Introduction

An abscess is a localized collection of pus contained within a fibrous capsule, which includes polymorphonuclear cells, necrotic leucocytes, infective organisms, and tissue cells. ¹ Many types of microorganisms like bacteria, viruses, fungi, and even parasites within an abscess can invade organs in the body, resulting in severe infection and leading to severe morbidity and even mortality. ² Previous studies have demonstrated that polymicrobial aerobic and anaerobic organisms are the most common etiology of an abscess, and there is a correlation between the anatomical site of the infection and the bacterial flora involved. ³

The objectives of the present study were to determine the demographic pattern, common anatomical sites, risk factors, and the microbial profile of abscesses in different body sites among children.

Methods

Between January 2019 and December 2022, we conducted a prospective study in our pediatric surgical department including children with abscesses in different body sites. All children from 0 to 14 years who attended our center with abscess in different body sites were included in the study. We excluded children whose parent or guardian did not consent to the child participating in the study. All children included in this study had a previous history of antibiotic therapy overuse.

All children underwent surgical procedures involving incision and drainage of the abscess. Pus aspirate samples were collected after abscess drainage and were immediately sent and processed in the microbiology laboratory. Standard biochemical tests were performed for the identification of causative organisms and the pus specimens were cultured. Postoperative oral antibiotic therapy was given to all children for 6 days. During the follow-up period, children's parents were instructed in how to properly care for and promote healing of the wound.

Statistical analysis was conducted using R version 4.4.1 (www.r-project.org). We used the Z test for conducting the analysis and descriptive statistics. This study is reported according to The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement. ⁴

Ethics approval and consent

This study was approved by the Ethics Committee of the University of Anbar College of Medicine (reference number 434). Written informed consent for study participant and publication was obtained from the legal guardian of all children with the understanding that every effort will be made to conceal the identity of the child. Patients’ details were de-identified.

Results

During the study period of January 2019 and December 2022, 85 children with abscess aged 0 to 14 years were enrolled in this study, including 56 (66%) male and 29 (34%) female patients. The age distribution among children with abscess was less than 2 years old (40 patients), age 2 to 5 years (10 patients), and age 5 to 14 years (35 patients).

The most common anatomical sites for abscess were the pelvis (34%), abdomen (26%), neck (16%), and extremities (14%) (Figure 1).

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Figure 1.

Abscess body sites in children with abscess.

In our study, the main risk factors for abscesses in different body sites included cannulation, lymphadenitis, mastitis, perforated appendix, and perianal fistula (Table 1).

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Table 1.

Risk factors according to abscess site.

Site of abscess	Etiology
Head	Cannulation
Neck	Infected lymph nodes
Breast	Neonatal mastitis
Abdomen	Perforated appendix or viscera
Pelvis	Perianal fistula, insect bite
Extremities	Cannulation

We observed that 74% of abscesses were polymicrobial in nature and 26% of abscesses were monomicrobial (Figure 2). Aerobic gram-negative bacilli and anaerobic gram-negative bacilli were the most prevalent bacteria isolated from samples of abdominal and pelvic abscesses (Table 2).

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Figure 2.

Distribution of microorganisms isolated from abscess samples.

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Table 2.

Most common microorganisms isolated from abscesses in different body sites.

Infection site	Types of microorganism
Head and neck	Aerobic gram-positive cocci
Abdomen	Aerobic gram-negative bacilli, Anaerobic gram-negative bacilli
Pelvis	Aerobic gram-negative bacilli, Anaerobic gram-negative bacilli
Extremities	Aerobic gram-positive cocci
Breast	Aerobic gram-positive cocci

Discussion

The present study was conducted in the Department of Pediatric Surgery. The key findings of our study were as follows. Of a total 85 children with different types of abscess, 66% were boys and 34% were girls, which is in line with other related studies.^1,5–8 The reason for the male preponderance in our study is that perianal fistula and perforated appendix, which were among the main risk factors for abscess, are slightly more common in male individuals.

The age range of our patients was from 0 to 14 years old, with most patients aged 0 to 2 years (n = 40), followed by age 5 to 14 years (n = 35). Another study ⁸ found that of 369 patients with ear abscess, 28% were less than 5 years old, 22% were aged 15 to 24 years, and 20% were aged 5 to 14 years.

In our study, the most common anatomic sites for abscesses were the pelvis (34%), abdomen (26%), neck (n = 16%), and extremities (14%). Talbot et al. ⁹ found that the most common site of abscess were the extremities (58%) and pelvis (25%). Gupta et al. ¹ reported that of 35 patients, the most common body sites of abscesses were the limbs (n = 11), breast (n = 7), and liver (n = 4). In the present study, the main risk factors for abscesses in different body sites were cannulation, lymphadenitis, mastitis, perforated appendix, and perianal fistula. Gupta et al. ¹ reported that the most common risk factors of abscesses included diabetes mellitus, appendicitis, and lactation. These discrepant results may be owing to differences in sample sizes and demographic patterns.

Abscesses can occur at any site in the human body, and each type of abscess has different characteristics. Abscesses are generally associated with multiple organisms. ¹⁰ Culture-based studies have shown that 44% of splenic abscesses, ¹¹ 11% to 40% of liver abscesses,^8–11 and 11% to 18% of intracranial abscesses^7,10 are polymicrobial in nature. Brook ³ found that of 52 intra-abdominal abscess specimens, 65% were mixed anaerobic and aerobic infections and 90% were polymicrobial. In our study, 74% of abscesses were polymicrobial and 26% abscesses were monomicrobial. The explanation for a polymicrobial nature in abscess formation remains poorly understood. Further studies should focus on the relationship between a previous history of antibiotic overuse and bacteria present in abscesses. Our study highlights the importance of aerobic gram-positive cocci as potential agents in abscesses of the head, neck, breast, and extremities. Aerobic gram-negative bacilli and anaerobic gram-negative bacilli were the most prevalent bacteria found in abdominal and pelvic abscesses in our study. The microbiology of intra-abdominal and perirectal abscesses mainly comprises the same types of organisms and is made up of bowel flora at the level of the visceral perforation. The main organisms isolated from these locations are anaerobic bacteria (Bacteriodes fragilis group) and facultative bacteria including Enterobacteriaceae. In the oro-facial, neck, and dental areas including peritonsillar, parotic, retropharyngeal, and cervical lymph nodes abscesses, the oral flora are mainly involved. The main organisms isolated from these locations are anaerobes and aerobic Streptococcus pyogenes and Staphylococcus aureus. ³ Sharma and Anuradha found that the most common cause for the development of ascites fluid with infection was gram-negative organisms (90%), with Escherichia coli the most common isolate (35%), followed by Acinetobacter spp. (26.8%) and Klebsiella spp. (21.9%). ²

This study has several limitations. The research was carried out in one department of a single hospital, which limits the generalizability of the findings to a single geographic area. The sample size of this study was relatively small, with 85 children. We did not specify the follow-up duration, so many complications in patients could have been missed.

Conclusion

In this study, the most common anatomical sites for abscess were the pelvis, abdomen, neck, and extremities. Most abscesses in these sites were polymicrobial. Aerobic gram-positive cocci were the most prevalent bacteria isolated from abscess samples of children in this study. Aerobic gram-negative bacilli and anaerobic gram-negative bacilli were the most prevalent bacteria found in abdominal and pelvic abscesses.

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