Appendicitis is an acute abdomen caused by bacterial infection. The treatment of appendicitis consists of surgical removal of the appendix and antibiotic administration. For non-perforated appendicitis, antibiotic treatment plays an important role in preventing postoperative wound infection and intraperitoneal abscess(10). It has been reported that patients who have received an emergency appendectomy should accept preventive antibiotic therapy(11, 12). A medical letter proposed guidelines for the selection of antibiotic therapy for appendicitis patients(13). Sandra I. Berríos-Torres et al. suggested that it is not necessary administer appendicitis patients antibiotic treatment postoperatively(14). However, for perforated appendicitis, antibiotic therapy is necessary. Empirical antibiotic therapy should treat gram-negative bacilli and anaerobic bacteria, and the antibiotics used should be adjusted according to the results of bacterial culture, which is in accord with most reports. However, due to the limitation of technology, only 1% bacteria can be successfully cultured. As shown in Table3, Escherichia coli could be cultured in all samples and was not the most abundant bacterium in either the culture positive or negative groups. Furthermore, bacterial requires a great deal of time, longer than is acceptable in some instances. Thus, simply using bacterial culture results will introduce bias in the selection of antibiotics. In the present study, we used next-generation sequencing to examine bacteria in the guts of patients to completely characterize appendicitis-associated pathogenic bacteria. Our results showed that the next-generation sequencing results were not in accord with those of bacterial culture, further suggesting that bacterial culture has limits in guiding the use of antibiotics in clinical practice.
By using next-generation sequencing, we did not observe any significant difference between the bacterial culture negative and positive groups, nor between the phlegmonous and gangrenous groups. Hope T. Jackson et al. extracted DNA from the microbiota of non-perforated and perforated appendixes for use in 16S rRNA gene sequencing analysis and observed a significant difference between non-perforated and perforated samples(4). Martin Salö et al. conducted a study of 3 control samples, 11 phlegmonous samples, 4 gangrenous samples and 4 perforated samples. They also utilized 16S rRNA gene sequencing but did not observe a significant difference among the different groups(8). Our results demonstrated that there was not significant difference in the microbiota between the non-perforated and perforated appendicitis groups, suggesting that antibiotic selection does not need to be altered based on bacterial culture results. However, we advise that medical institutions should use next-generation sequencing to regularly reanalyze the microbiota spectrum of appendicitis patients and assess the presence drug resistance genes to allow for antibiotic treatments to be adjusted in a timely manner.
Specifically, completely excising lesions of the appendix and eliminating all the intraperitoneal effusion are the most important tasks in the treatment of appendicitis. Different acute abdomens harbor different bacterial species. Because of the similar bacterial species, appendicitis has similar pathogenesis among individuals(15). In the light of all the above deficiencies, it is difficult to make an optimal decision om antibiotic usage based on bacterial culture results alone. Moreover, bacterial species and drug resistance genes change over time. Antibiotic resistance determinants are encoded by several genes, many of which can be transferred between bacteria(16). Thus, next-generation sequencing should be used to examine drug resistance genes at a regular intervals to adjust the choice of antibiotics. However, the cost of next-generation sequencing is high, making it difficult to use on all patients.
Based on the results of the present study and those of previous studies, we propose that a combination of next-generation sequencing and bacterial culture technology should be used guide treatment of appendicitis. Next-generation sequencing can be used to examine the bacterial species present in the appendix and analyze their of drug resistance profiles. Before empirical antibiotic treatment of appendicitis patients, bacterial culture should be performed to assess refractory infections and evaluate the species of bacteria present throughout the treatment period. The combination of next-generation sequencing and bacterial culture will improve the effects of treatments and the use of medical resources. From the perspective of pharmacists, we suggest that we can regularly monitor the top 10 abundant of bacteria to provide evidence that allows them to make antibiotic prescription recommendations.
Our research has several limitations. First, the sample size of our study was small. We collected samples from 22 patients, which may affects the reliability of our results. However, we utilize next generation sequencing in our research, and rather than 16S rRNA gene sequencing, we performed metagenomic sequencing to evaluate all the genes present to the fullest extent possible. The second limit of our research is the use of antibiotics. Before we collected the samples, all patients had already accepted antibiotic treatment, which may also have affected the results of our study. Thus, samples without antibiotic treatment should be evaluated to avoid alterations in the composition of the gut microbiota of appendicitis patients. However, performing such an analysis would be impossible, since antibiotic treatment is an important part of the standard treatment of appendicitis patients. Moreover, our analysis was based on DNA, which is stable enough to resist the influence of antibiotics. After bacteria are killed by antibiotics, their DNA can still can be examined, although its copy number would decrease over time. Since the time between antibiotics administration and surgery is short, it is unlikely that antibiotic administration would substantially altered our results.