1. Background
Acute gastroenteritis (AGE) refers to the inflammation of the mucous membranes lining the digestive tract that causes diarrhea and vomiting and is transmitted through person-to-person contact and the consumption of contaminated food (1). AGE is one of the most common human infectious diseases that affects more than 2.5 billion children annually (2, 3). AGE occurs in both developing and developed countries and is the second leading cause of child mortality worldwide; approximately 1.5 million children under the age of five die annually due to the incidence of the disease (4, 5). Viruses, bacteria, and parasites are the three main groups of agents that produce AGE in children, with viruses accounting for over 80% in this population (2). The most common bacteria responsible for AGE in children are Escherichia coli, Shigella, Salmonella, and Campylobacter, and they can cause serious gastrointestinal and non-gastrointestinal complications despite their lower incidence than viral factors (6, 7).
The Campylobacter genus is a Gram-negative, curved, motile, thermophilic, and microaerophilic bacillus that does not produce spores (8) and is comprised of 26 species, the most important of which are Campylobacter jejuni and Campylobacter coli (9). Gastroenteritis, meningitis, and septicemia are considered as the most important infectious diseases caused by Campylobacter (9). Campylobacter is one bacterial cause of AGE in developed countries (10). In developed countries, Campylobacter accounts for about 5% - 20% of all cases of AGE in children younger than 5 years of age; in developing countries, this incidence ranges from 5% - 35% (11, 12). Campylobacter is transmitted through food and water and appears more often during the warm seasons (13). Although diarrhea caused by Campylobacter is self-limiting in nature, antimicrobial therapy can reduce the severity of symptoms and shorten the course of the disease (14).
The quality of treatment for patients can be improved with the proper differentiation of diarrhea caused by Campylobacter from that precipitated by other factors. Cultivation of this organism, however, entails a period of about 48 - 72 hours, which can lead to a delay in the initiation of treatment.
Knowledge of the epidemiology as well as the clinical and laboratory symptoms of AGE caused by Campylobacter will thus significantly contribute to improving the diagnosis and treatment process and thereby also reduce the incidence of complications from the infection.
Despite numerous studies on the frequency of this pathogen in different areas, clinical and laboratory symptoms of children suffering from Campylobacter infection have received little attention.
2. Objectives
This study was designed and implemented to evaluate the frequency level as well as the clinical and laboratory symptoms of diarrhea caused by Campylobacter in children with AGE in the city of Semnan, Iran.
3. Patients and Methods
3.1. Study Design and Participants
In this cross-sectional study, 419 children aged 1–12 years were examined during the period from July 2014 to January 2015.
Given the results of Sorokin et al.’s study, in which the frequency of diarrhea caused by Campylobacter spp. was reported to be 10.5%, the sample size was calculated as 419 by assuming Z1-ɑ / 2 = 1.96 and d = 0.03 using the Kish Leslie formula (15).
All children referred to the pediatric emergency department of Semnan Imam Ali hospital with the complaint of acute diarrhea were selected for this study using a convenience sampling method until the required sample size was reached. In addition, children treated with fever-reducing drugs or methods were excluded, as were children who had received antibiotics within the previous two weeks or who suffered from anomalies of the gastrointestinal tract. After the provision of information on how to perform the study, written informed consent to participate in the study was obtained from the parents of the children, whose demographic and clinical information (including abdominal pain, vomiting, and dehydration) were then recorded in a questionnaire. The tympanic temperature in the children was measured and recorded using a Braun Thermo Scan 5 IRT4520 digital thermometer that had been previously calibrated by the provider. Tympanic temperatures above 38°C were considered to be a fever.
3.2. Specimen Sampling and Laboratory Procedures
Five mL of venous blood were taken from all children by a qualified nurse. All samples were sent to the lab with a previously recorded identification (ID) number for blood cell count tests using the Sysmex KX-21N cell counter; the number of white blood cells (WBCs) was then recorded in the questionnaire. Leukocytosis was defined as a WBC count higher than the age-dependent upper reference value (16).
Before starting treatment with antibiotics, two samples were collected from the stools of patients: part of the sample was collected in sterile containers for the preparation of smears and to determine the red blood cell (RBC) and WBC count of the patients’ stool (HiMedia, India). For bacteriological examination under sterile conditions, some of the patients’ stool was transferred with a loop to Cary-Blair medium (MP202, HiMedia, India), where the sample was stored at 4°C before being sent to the laboratory. More than 5 RBCs and WBCs per high-power field [HPF] were considered positive for RBCs or WBCs.
The culture method was used to evaluate Campylobacter strains in the sample. The sample was moved using a sterile loop from the transport medium to the Skirrow’s medium (MP994, HiMedia, India), where it was cultured using the Strick method. The prepared plates were microaerophilically incubated at 42°C for 48 - 72 hours using gas packs. Smears were taken from the colonies that appeared on the Skirrow’s medium, and Gram staining was performed to assess the morphology of the organism. In addition, oxidase and catalase tests were carried out on all positive cultures, and any samples containing curved Gram-negative organisms (which were positive for oxidase and catalase production) were considered positive for the presence of Campylobacter.
3.3. Statistical Analysis
Data were analyzed using the statistical package for the social sciences (SPSS) version 18. Descriptive results were reported using absolute and relative abundance. After the data distribution was assessed by the Kolmogorov-Smirnov test, the average age between genders was compared using the Mann-Whitney U test, given the abnormal distribution of data on the patients’ ages.
The demographic, clinical, and laboratory characteristics of patients were compared using the chi-square test. The odds ratios and 95% confidence intervals were then reported. P values less than 0.05 were considered statistically significant.
4. Results
In total, 419 children were examined; they were mostly female (n = 233, 55.6%) with a mean age of 6.3 ± 3.36 years. The highest frequency age group included participants from 6 - 12 years (203 patients, 48.4%). During the visit, 23.9% of participants reported abdominal pain, 49.2% had vomiting, 25.5% reported a fever, and 71.6% experienced symptoms of dehydration. The characteristics of the study population are shown in Table 1.
Table 1. Demographic and Clinical Characteristics of the Study Population
| Variable | Gender | P Value | |
|---|---|---|---|
| Male (n = 186) | Female (n = 233) | ||
| Agea | 6.48 ± 3.36 | 6.16 ± 3.37 | 0.36 |
| Age groupb | 0.39 | ||
| < 2 | 27 (14.5) | 45 (19.3) | |
| 2 - 6 | 68 (36.6) | 76 (32.6) | |
| < 6 | 91 (48.9) | 112 (48.1) | |
| Abdominal Painb | 0.43 | ||
| No | 145 (78.0) | 174 (74.7) | |
| Yes | 41 (22.0) | 59 (25.3) | |
| Vomitingb | 0.14 | ||
| No | 87 (46.8) | 126 (54.1) | |
| Yes | 99 (53.2) | 107 (45.9) | |
| Dehydrationb | 0.36 | ||
| No | 57 (30.6) | 62 (26.6) | |
| Yes | 129 (69.4) | 171 (73.4) | |
| Feverb | 0.21 | ||
| No | 144 (77.4) | 168 (72.1) | |
| Yes | 42 (22.6) | 65 (27.9) | |
aValues are expressed as mean ± SD.
bThe values are presented as No. (%).
Microscopic examination of the stool samples showed the presence of RBCs in 29 patients (6.9%) and WBCs in 114 patients (27.2%). A complete blood count indicated the presence of leukocytosis in 201 patients (48.0%). Thirty-six participants (8.6%) had positive bacteriological examinations for infection with Campylobacter strains, and the frequency of diarrhea caused by Campylobacter was 6.4% and 10.3% in boys and girls, respectively. Table 2 shows the demographic, clinical, and laboratory characteristics of children with acute gastroenteritis by etiologic agent.
Table 2. Demographic, Clinical, and Laboratory Characteristics of Children Both With and Without Campylobacter Infection
| Variablea | Campylobacter | P Value | OR (95% CI) | |
|---|---|---|---|---|
| Positive | Negative | |||
| Gender | 0.16 | 1.66 (0.81 - 3.43) | ||
| Male | 12 (33.3) | 174 (45.4) | ||
| Female | 24 (66.7) | 209 (54.6) | ||
| Age group | 0.02 | - | ||
| < 2 | 10 (27.8) | 62 (16.2) | ||
| 2 - 6 | 5 (13.9) | 139 (36.3) | ||
| < 6 | 21 (58.3) | 182 (47.5) | ||
| Abdominal pain | < 0.001 | 15.12 (6.61 - 34.55) | ||
| No | 8 (22.2) | 311 (81.2) | ||
| Yes | 28 (77.8) | 72 (18.8) | ||
| Vomiting | 0.13 | 1.7 (0.84 - 3.42) | ||
| No | 14 (38.9) | 199 (52.0) | ||
| Yes | 22 (61.1) | 184 (48.0) | ||
| Dehydration | 0.39 | 1.43 (0.63 - 3.23) | ||
| No | 8 (22.2) | 111 (29.0) | ||
| Yes | 28 (77.8) | 272 (71.0) | ||
| Dehydration severity | 0.38 | - | ||
| Mild | 150 (54.3) | 19 (67.9) | ||
| Moderate | 80 (29.0) | 6 (21.4) | ||
| Severe | 46 (16.7) | 3 (10.7) | ||
| Fever | 16.2 (6.84 - 38.36) | |||
| No | 7 (19.4) | 305 (79.6) | ||
| Yes | 29 (80.6) | 78 (20.4) | < 0.001 | |
| Leukocytosis | 0.002 | 3.09 (1.45 - 6.58) | ||
| No | 10 (27.8) | 208 (54.3) | ||
| Yes | 26 (72.2) | 175 (45.7) | ||
| Stool WBC | < 0.001 | 5.68 (2.76 - 11.66) | ||
| No | 13 (36.1) | 292 (76.2) | ||
| Yes | 23 (63.9) | 91 (23.8) | ||
| Stool RBC | 0.3 | 1.79 (0.59 - 5.46) | ||
| No | 32 (88.9) | 358 (93.5) | ||
| Yes | 4 (11.1) | 25 (6.5) | ||
aValues are expressed as No. (%).
5. Discussion
In this study, 419 children with acute gastroenteritis were examined for infection with Campylobacter strains, and Campylobacter was the cause of diarrhea in 8.6% of the participants. Several Iranian studies have obtained different values than those reported in our study. Feizabadi et al. (17) investigated 500 Tehrani children with acute diarrhea, and the frequency of Campylobacter strains in their stool cultures was reported to be 8%; over 85% of these were Campylobacter jejuni. According to Alborzi et al.’s study (18) of 719 Iranian children to investigate the etiology of acute gastroenteritis in Shiraz, 2% of the cases of acute diarrhea in children were caused by Campylobacter strains. Dallal identified a frequency of 0.9% for Campylobacter strains in acute diarrhea among children younger than 5 years of age in south Tehran (19). Various studies have reported Campylobacter frequencies, such as 3.0% in Senegal, 8.4% in Uruguay, 9.6% in Egypt, 9.7% in Tanzania, 9.3% in Uganda, 10.5% in Romania, 11.0% in Sudan, 12.7% in Ethiopia, and 22.6% in Ghana (11, 12, 15, 20-25). Therefore, the average contribution of Campylobacter strains to AGE in children was about 9% in most studies. The significant differences observed in some studies necessitate epidemiological examinations in different regions to better understand the etiological status of acute diarrhea in children.
This study found that 47.5% of cases of diarrhea caused by Campylobacter occurred in children aged 6 - 12 years and there is a relationship between age group and infection with AGE caused by Campylobacter. Relevant studies have shown inconsistent results. According to a study conducted in Shiraz, children over the age of 11 years had the highest incidence of Campylobacter (26). In contrast, Rathaur et al. (27) found that the age group from 1 - 3 years made up 52.9% of patients with Campylobacter diarrhea. Children from 2 - 5 years of age had the highest risk of diarrhea caused by Campylobacter in a Ghanaian study (26). In addition, a Polish study of all cases of Campylobacteriosis diagnosed in 2012 revealed that over 79% of patients were younger than 4 years (28), while German children aged 1 - 4 years constituted the majority of patients in a 10-year study of Campylobacteriosis (29). A review of the studies that included a wide (statistical) population indicated that most Campylobacter infections occur from the ages of 1 - 5 years. A meta-analysis should make the situation clearer.
In this study, fever, abdominal pain, leukocytosis, and WBCs in the stool were associated with diarrhea caused by Campylobacter. Different results have been found in the few existing relevant studies. One report on children under 5 years merely noted a relationship between the frequency of Campylobacter and abdominal pain (30); the frequency of fever, vomiting, and dehydration in another study was similar in several different types of diarrhea caused by bacterial pathogens (27). A comparison between children with Campylobacter diarrhea and those with diarrhea caused by Salmonella showed a relationship between Campylobacter and abdominal pain and leukocytosis; four criteria have been recommended for the differentiation of Campylobacter diarrhea: age over 5 years, leukocytosis, abdominal pain, and diarrhea (31). Based on the evidence and results of this study, abdominal pain is a common clinical symptom in patients with Campylobacter, but other clinical and laboratory findings are not reliable enough; the epidemiological situation and clinical and laboratory symptoms must therefore be considered for the diagnosis of AGE caused by Campylobacter. Further studies will be required to develop reliable diagnostic criteria.
This study is one of the few that has included a wide population; it also attempted to use the most precise equipment to measure the clinical, bacteriological, and laboratory variables to evaluate the clinical and laboratory symptoms of AGE caused by Campylobacter in children. There were some limitations to the study as follows. Campylobacter strains cannot be determined exactly, and differences in the development of symptoms in various strains may disrupt the careful examination of the study variables. Therefore, future studies should consider the role of different strains in developing clinical and laboratory symptoms.
