Analysis of pathogen distribution and antimicrobial resistance at infected sites in plastic surgery

By analyzing the distribution and drug resistance of common pathogen in different sites in plastic surgery to provide reference for clinicians to choose the best antibacterial treatment plan.


| INTRODUC TI ON
Infection is one of the common complications in plastic surgery and the leading cause of delaying wound recovery, an extended treatment time, poor cosmesis, and even letting deformities. Higher requirements were demanded in the healing quality and appearance of the wound in plastic surgery, which was the fusion of medicine and aesthetics. Various treatment methods such as flap transplantation, application of expander, foreign body implantation, and bacterial colonization in some treatment areas 1 will increase the risk of infections. Therefore, the prevention of infections between the perioperative and treatment period is of utmost importance in plastic surgery.
In addition, the irregular abuse, misuse, and overuse of antibiotics lead to the emergence of antibiotics-resistant bacterial strains and high selective antibiotic pressure, which accompany with the increasing morbidity and mortality of infection. Numerous studies have revealed that reasonable antibiotic application of antibiotics can reduce medical costs, the incidence of infection, and the colonization prevalence of drug-resistant strains. 2 Previous studies have mostly focused on the profile and the antibiotic resistance of microorganisms from the perspective of specimen type and bacterial classification, and few studies were conducted from the perspective of infected sites. In addition, the first use of antibiotics is usually performed without microbiological results, and mostly based on the epidemiology of microbiology. Therefore, it is crucial to investigate the distribution differences and drug resistance characteristics of common pathogenic bacteria in different parts of plastic surgery to provide useful and valuable scientific evidence and information for the prevention, control, and treatment of infections in plastic surgery.

| Clinical specimens
A retrospective study was performed to analyze the information of patients infected after plastic surgery in the plastic surgery hospital located in Beijing from January 2011 to December 2021. In this study, the presence of one of the following symptoms was considered as infection, including erythema, local warmth, swelling, purulent discharge, delayed wound healing beyond expectations, new or increasing pain, and increasing malodour. 3  therefore, a total of 11 antibacterial drugs selected for gram-positive bacteria were used in this study, including cefoxitin, cotrimoxazole, penicillin, clindamycin, tetracycline, levofloxacin, erythromycin, vancomycin, chloramphenicol, gentamicin, and linezolid. Drug-sensitive piece of paper came from the British Oxoid company. The quality control strains were S. aureus (ATCC25923), Escherichia coli (ATCC25922), Pseudomonas aeruginosa (ATCC27853), and Enterococcus faecalis (ATCC29212). The identified strains were stored at −80°C.

| Statistical analysis
Data were primarily input and processed using Microsoft Excel 2016, and percentages were calculated. The categorical data were expressed as frequencies and percentages. The statistical analysis was performed using SPSS 19.0 (IBM analytics) and WHONET 5.6 software. Trend chi-square test (linear-by-linear association) was used to analyze whether there was a linear relationship between the detection rates of pathogen and years. p < 0.05 indicated that there was a linear trend between the detection rates of pathogen and years. For pathogens with a linear trend with the years, use Microsoft Excel 2016 to make trend charts and determine trend direction.  Table 1. Of the gram-negative bacteria, P. aeruginosa had the highest percentage (137/465) ( Table 2). Overall, from 2011 to 2021, the detection rates of Enterococci and P. aeruginosa showed a downward trend (p < 0.05), while the detection rate of E.coli showed an upward trend (p < 0.05). There was no obvious variation trend in other strains (p > 0.05), as shown in Figure 1.

| The change trends of MRSA and MRCNS
From 2011 to 2021, the detection rates of MRSA and MRCNS in our hospital showed an upward trend, as shown in Table 3.

| The pathogen distribution in different sites
As shown in Table 4, E. coli (18/76) and P. aeruginosa (9/76) were the most common pathogen of perineum. In oral cavity, S. aureus (13/ was the most frequent pathogen, followed by P. aeruginosa (12/61).
In other parts in our study, the predominant pathogen was S. aureus, and secondly CoNS.

| Antimicrobial Resistance of S. aureus in different parts
As mentioned，S. aureus was the most common types of grampositive bacteria in all parts, all of them were completely sensitive to vancomycin. As shown in In addition, the erythromycin resistance rate of neck and perineum was also 100%, as shown in Table 6.

| DISCUSS ION
Infections have always been one of the common and feared complications after plastic surgery. Two main factors contribute to the postoperative infections. Frist, some treatment area of plastic surgery such as ear, nose, oral cavity, breast, and perineum are colonized by opportunistic pathogens. Once the colonization bacteria break through the barrier, they can invade the body and cause infection. [5][6][7] Second, infection is a common complication after the application of foreign bodies such as expanders and prostheses. 8,9 In addition, some studies also revealed that the implants contaminated with bacteria were the main cause of infection. 10,11 Hence, the infection has become a great challenge for plastic surgery. In recent years,     past. However, at present, some strains of CoNS are recognized as opportunistic pathogens, which is the most common bacteria in clinical nursing and closely related to the application of medical equipment due to the emergence and rapid spread of methicillin resistance. 16,17 The second most common pathogen in the breast infection in our study was CoNS, accounting for more than 25%.

Cases (n) MRSA (n) Proportion (%) Cases (n) MRCNS (n) Proportion (%)
However, Mesa et al. 18  Although currently linezolid can be used for severe gram-positive infections with methicillin resistance and has been used in a variety of diseases with CoNS infections, we cannot ignore the phenomenon of linezolid resistance. Therefore, it is more necessary to refine medication principle according to infection site and formulate strict and reasonable medication indications.
The proper use of antibiotics is critical to reducing the emergence of resistant strains. The selection of antibiotics is often based solely on the type of pathogen in the past; however, we found that there were differences in pathogen species and drug sensitivity characteristics in different parts of infections. Therefore, summarizing the common types of pathogens, understanding the characteristics of drug sensitivity of pathogens in different parts, and taking the differences of anatomic site as one of the references for medication are helpful to improve the accuracy of empirical use of antibiotics and provide suggestions for formulating prevention and control measures.

AUTH O R CO NTR I B UTI O N S
Sien Zhan and Jintian Hu developed the idea and provided the methodology for the study. Fengli Jiang analyzed the data and wrote the paper. Xueshang Su collected the data and wrote the paper. The remaining authors contributed to refining the ideas, discussing the results, and revising the manuscript.

FI N A N CI A L D I SCLOS U R E S TATEM ENT
The authors have no financial interest to declare in relation to the content of this article.

ACK N OWLED G EM ENT
We are grateful that this work was supported by the National Natural Science Foundation of China (81671933) and the Key Medical Discipline Research Project of Beijing Shijingshan District.

DATA AVA I L A B I L I T Y S TATA E M E N T
The data that support the findings of this study are available from the corresponding author upon reasonable request.

E TH I C A L S TATEM ENT
The authors confirm that the ethical policies of the journal, as