Assessment of serum parameters caused by the outbreak of mycoplasma pneumoniae pneumonia in children after COVID-19

Abstract

Mycoplasma pneumonia pneumonia(MPP) is a common respiratory disease that often occurs in children. The purpose of this study was to explore the clinical characteristics of children with mycoplasma pneumoniae pneumonia, the first outbreak after the prevalence of COVID-19 epidemic. Meanwhile, this study also analyzed the predictive value of serum protein indicators and coagulation parameters in the MPP group, as well as the correlation between these indicators. Children with Mycoplasma pneumoniae admitted to the pediatric ward of Chengdu Fifth People’s Hospital from May 2023 to March 2024 were selected. After screening, 411 children who met the research criteria were selected as the study subjects. All of the blood samples were tested for coagulation function, procalcitonin, serum protein and glucose among MPP group and control group. All data were processed for statistical analysis using GraphPad Prism 10.2.3. Comparison of the serum proteins and coagulation function between the MPP group and control group showed that prothrobin time(PT), thrombin time (TT), fibrinogen(Fbg), activated partial thromboplastin time (APTT), international normalized ration(INR), D-Dimer(DD) were significantly higher(P < 0.05) in MPP group. Total protein, albumin, prealbumin, alkaline phosphatase, lactate dehydrogenase, adanosine deaminase, glucose, platelet, procalcitonin also were significantly higher(P < 0.05) in MPP group. A multiple logistic regression analysis showed that the children in MPP group were a statistically significant difference in comparison of TT, Fbg, total protein, albumin, glucose, platelet expression in predicting the development. Then we analyzed the area under the ROC curve and correlation of serum parameters with significant differences in MPP group children. These results indicate that the coagulation function and serum protein of MPP patients who first broke out after the COVID-19 epidemic are different from the previous clinical characteristics, which can be used as a reference for auxiliary diagnosis.

Introduction

Mycoplasma pneumoniae is the smallest and simplest self-replicating pathogen available, with a hammer-shaped shape that sits between bacteria and viruses^1,2. During the infection cycle of Mycoplasma pneumoniae pneumonia, Mycoplasma pneumoniae multiplies in the host body and releases many toxic metabolites that can cause damage to host cells^3,4. Pneumonia is currently a major issue affecting children’s health worldwide^5,6. With the use of vaccines and changes in the pathogen spectrum, Mycoplasma pneumoniae has become one of the most common pathogens of community-acquired pneumonia and up up 70% in some areas of China⁷. In addition, the incidence rate of MP infection is increasing in both northern and southern regions, and a regional epidemic occurs every 2–3 years or so, both in autumn and winter^8,9.

After the COVID-19 outbreak in 2019, more than 90% of the population in Chinese mainland had received three doses of COVID-19 vaccine. After the cancellation of the COVID-19 blockade policy in 2023, the number of children infected with Mycoplasma pneumoniae continues to rise^10,11. Subsequently, pneumonia caused by Mycoplasma pneumoniae infection appeared in Chengdu, Sichuan Province. In the study, we retrospectively collected 578 hospitalized children with pneumonia who tested positive for Mycoplasma pneumoniae nucleic acid and had fever from May 2023 to March 2024, Among them, 411 children met our research criteria. We analyzed the coagulation function, blood routine, biochemical indicators, glucose, and procalcitonin levels these 411 pediatric patients. Compared with the normal control group, some of the parameters are significant higher than the normal control group, with significant differences, and are also significantly different from other scholar’s studies. It can be seen that the experimental indicators of Mycoplasma pneumoniae pneumonia, the first epidemic in children after the COVID-19 epidemic, are different from those in the past.

Materials and methods

Participants and hospital settings

The retrospective study was conducted in Chengdu City, Sichuang Province, China, from May 2023 through March 2024. All pediatric patients were inpatients in the pediatric ward of the Chengdu Fifth People’s Hospital, Chengdu University of Traditional Chinese Medicine, a 2188-bed tertiary care government hospital. The subjects were recruited consecutively in the pediatric ward which was composed of three separate units that had 129 beds. They all met the diagnostic criteria of the MPP diagnosis and treatment expert consensus(2023 version) for children. MPP diagnostic criteria: A diagnosis can be made based on medical history, clinical symptoms, signs, and imaging findings, as well as meeting one of the following positive laboratory diagnostic criteria(1) MP antibody titer increases by four times or more during the recovery phase compared to the acute phase; (2) MP culture positive or MP-DNA or RNA positive. The clinical feature were mainly fever, cough, with or without respiratory distress or other systemic symptoms, such as dry and wet rales in the lungs, accompanies by signs of lung consolidation and changes in the lungs. PCR is the gold standard for diagnosing Mycoplasma pneumoniae infection for its high specificity than serology.

Clinical characteristics

The clinical characteristics included gender, age, prothrombin(PT), thrombin time(TT), activated partial thromboplastin time(APTT), fibrinogen(Fbg), D-Dimer(D2), total protein, albumin, prealbumin, alkaline phosphatase(ALP), lactate dehydrogenase(LDH), adenosine deaminase(ADA), procalcitonin(PCT), glucose, platelet(PLT). In this case-control study, 100 health children come from children who underwent health check up during the same period. The coagulation parameters were determined by testing the serum samples on SEKISUI; platelet was performed on Mindray BC-6800; PCT was determined by MACCURA; total protein, albumin, prealbumin, alkaline phosphatase, lactate dehydrogenase, adenosine deaminase, glucose were performed by the Hitachi 7180 automatic biochemical analyzer. During the study, internal quality control, and rxternal quality assessment scheme of the study parameters were all controlled.

Statistical analysis

All statistical analyses were performed using GraphPad Prism 10.2.3. Data are presented as mean and standard deviation. The unpaired t-test was used to compared the two groups, and the correlation was compared using Pearson’s correlation coefficient. The area under the receive operating characteristic(ROC) curves were computed for clinical parameters. A logistic regression analysis of the risk factor in children with MPP was also performed. A P < 0.05 was considered statistically significant.

Ethical statement

The study was approved by the Ethics Committee of Chengdu Fifth people’s Hospital, and all methods were conducted according to Declaration of Helsinki and current ethical guidelines. The Ethics Committee of Chengdu Fifth People’s Hospital approved the retrospective study. Informed consent procedures, which were carried out individually. Additionally, written Informed consent was obtained from all of the parents before any procedures were performed.

Results

Clinical parameters

A total of 411 MPP children were evaluated and analyzed for this study. All cases with fever for more than 1 day. Most patients have cough, sore throat, and some children will have symptoms of headache and rhinitis. Demographic characteristics and laboratory data were collected from the subjects’ records. In addition, mycoplasma pneumoniae nucleic acid test was positive, influenza virus and COVID-19 nucleic acid test was negative. The clinical characteristics of these children were analyzed(Table 1). Significant difference were detected in PT, TT, INR, Fbg, D2,total protein, albumin, prealbumin, ALP, LDH, ADA, PCT, PLT in the two groups. Except for APTT, coagulation parameters in the MPP group were significantly higher than those in the healthy control group(P < 0.05). The mean glucose and PLT in MPP group(5.42 ± 0.93 mmol/L,322.15 ± 124.70 × 109/L) were significantly higher than of the control group(4.97 ± 0.48 mmol/L, 246.10 ± 49.48 × 109/L, p < 0.0001). The mean total protein, albumin, prealbumin, ALP, LDH, ADA, PCT, PLT, glucose in MPP group were also significantly higher than that of the health control group(p < 0.0001).

Table 1. Demographics of the study cohort.

Variables	Mycoplasma pneumoniae pneumonia group (n = 411)	Control group (n = 100)	P value	95% confidence interval	R squared (eta squared)
Gender (male/famale)	194/217	42/58
Age	6.89 ± 2.65	6.58 ± 2.16	0.2784	− 0.8713 to 0.2513	0.002308
Prothrombin (s)	14.57 ± 0.87	13.32 ± 0.48	< 0.0001	− 1.427 to − 1.073	0.2739
Thrombin time (s)	16.05 ± 2.25	17.38 ± 0.98	< 0.0001	0.8776 to 1.782	0.06151
international normalized ratio	1.20 ± 0.07	1.11 ± 0.04	< 0.0001	− 0.1043 to − 0.07571	0.2311
Activated partial thromboplastin time (s)	33.26 ± 4.23	32.39 ± 5.14	0.0782	− 1.839 to 0.09863	0.00608
Fibrinogen (g/L)	4.42 ± 0.78	3.64 ± 3.96	0.0002	− 1.192 to − 0.3678	0.02644
D-Dimer (mg/L)	1.39 ± 2.96	0.72 ± 0.12	0.0242	− 1.252 to − 0.08792	0.009947
Total protein (g/L)	68.88 ± 4.36	72.15 ± 3.50	< 0.0001	2.349 to 4.191	0.08717
Albumin (g/L)	40.77 ± 2.84	44.52 ± 2.24	< 0.0001	3.151 to 4.349	0.2292
Prealbumin (mg/L)	121.79 ± 38.88	249.65 ± 46.73	< 0.0001	119.0 to 136.7	0.6113
Alkaline phosphatase (U/L)	172.26 ± 79.33	76.12 ± 20.61	< 0.0001	− 111.9 to − 80.42	0.2209
Lactate dehydrogenase (U/L)	326.19 ± 100.15	180.77 ± 33.17	< 0.0001	− 165.4 to − 125.5	0.2872
Adenosine deaminase (U/L)	20.64 ± 5.16	11.38 ± 4.23	< 0.0001	− 10.35 to − 8.166	0.3522
Procalcitonin (ng/L)	0.27 ± 0.66	0.05 ± 0.01	0.0009	− 0.3498 to − 0.09023	0.02133
Glucose (mmol/L)	5.42 ± 0.93	4.97 ± 0.48	< 0.0001	− 0.6386 to − 0.2614	0.04137
Platelet (109/L)	322.15 ± 124.70	246.10 ± 49.48	< 0.0001	− 101.0 to − 51.07	0.06567

Multiple logistic regression analysis of parameters in patients with MPP

By comparing the coagulation parameters, total protein, albumin, ALP, LDH, ADA, glucose, PLT, we predicted the development of patients with MPP. However, there were statistically significant difference in PT, TT, Fbg, total protein, albumin, ADA, glucose, PLT(P < 0.05, Table 2).

Table 2. Multiple logistic regression analysis of parameters in patients with MPP.

parameters	P value	OR value	95% confidence interval (profile likelihood)
Prothrombin (s)	0.0483	0.005	0.0007160–0.01566
Thrombin time (s)	< 0.0001	1.293	1.118–1.471
Fibrinogen (g/L)	< 0.0001	0.5299	0.2632–1.002
Total protein (g/L)	< 0.0001	1.293	1.210–1.390
Albumin (g/L)	< 0.0001	0.7751	0.7201–0.8308
Prealbumin (mg/L)	0.3738	1.073	1.057–1.095
Alkaline phosphatase (U/L)	0.7373	0.8521	0.8074–0.8866
Lactate dehydrogenase (U/L)	0.5644	0.9594	0.9511–0.9667
Adenosine deaminase (U/L)	0.0002	0.6925	0.6376–0.7461
Glucose (mmol/L)	< 0.0001	0.4505	0.3198–0.6191
Platelet (109/L)	< 0.0001	0.9918	0.9887–0.9946

The ROC curve analysis

The receive operating characteristic(ROC) curve and the area under the curve(AUC) of parameters associated in patients with MPP showed statistically significant difference(P < 0.0001). Alkaline phosphatase expression had the largest area under the ROC curve(AUC), with an AUC of 0.9895. PLT expression had the smallest area under the ROC curve (AUC), with an AUC of 0.6723(Table 3).

Table 3. The ROC curve analysis.

parameters	Area	95% confidence interval	P value
Prothrombin (s)	0.9584	0.9405–0.9763	< 0.0001
Thrombin time (s)	0.9169	0.8907–0.9432	< 0.0001
Fibrinogen (g/L)	0.8454	0.8120–0.8788	< 0.0001
Total protein (g/L)	0.7915	0.7507–0.8323	< 0.0001
Albumin (g/L)	0.7018	0.6353–0.7683	< 0.0001
Prealbumin (mg/L)	0.9841	0.9734–0.9948	< 0.0001
Alkaline phosphatase (U/L)	0.9895	0.9800–0.9991	< 0.0001
Lactate dehydrogenase (U/L)	0.9375	0.9159–0.9591	< 0.0001
Adenosine deaminase (U/L)	0.8609	0.8257–0.8960	< 0.0001
Glucose (mmol/L)	0.6862	0.6429–0.7295	< 0.0001
Platelet (109/L)	0.6723	0.6285–0.7161	< 0.0001

Correlation analysis

Furthermore, we conducted a correlation analysis on the 11 parameters in Table 3 and plotted a heatmap(Fig. 1). The heatmap showed that these parameters have both positive and negative correlations, as well as no correlation. The maximum positive correlation value is 0.45(blue box), and the maximum negative correlation value is -0.58(red box).

Fig. 1 [Images not available. See PDF.]

Correlation analysis.

Discussion

Mycoplasma pneumoniae is a known pathogen that has been shown in many studies to cause disease in humans¹². Mycoplasma pneumonia is more common in children and adolescents¹³. After entering the body, Mycoplasma releases toxic metabolites that cause damage to the host, stimulate immune cells, and lead to immune hyperfunction, thereby causing pathological changes in the system^14,15. Some scholars believe that Mycoplasma pneumoniae pneumonia can affect the body’s coagulation function^16,17. Mycoplasma pneumoniae can activate the body’s coagulation and inflammatory systems¹⁸. After the first outbreak of Mycoplasma pneumoniae infection after the COVID-19, whether the clinical characteristics of the patients have changed from that before the COVID-19 outbreak, so this study also examined the clinical characteristics of children with Mycoplasma pneumoniae pneumonia, and analyzed the clinical characteristics that can provide reference for the diagnosis and treatment of the disease.

The results of the study showed that clinical variables, such as PT, TT, INR, Fbg, D2,total protein, albumin, prealbumin, ALP, LDH, ADA, PCT, PLT, were significantly higher in children with MPP group. Except for APTT, coagulation parameters in the MPP group were significantly higher than those in the healthy control group(P < 0.05). This is different from the results of coagulation indicators in patients with mycoplasma pneumoniae pneumonia before COVID-19. Most of the previous coagulation parameters were D-Dimer elevation¹⁹. It was found in the study that a mean PCT was higher in MPP groups, this result is similar to the immune status of Mycoplasma pneumoniae pneumonia before the COVID-19 epidemic²⁰. According to the ROC curve, we found that the area under the curve(AUC) of PT, TT, Fbg, total protein, albumin, prealbumin, ALP, LDH, ADA, PLT, glucose associated in patients with MPP showed statistically significant difference(P < 0.0001). Further correlation analysis will be conducted on these 11 indicators and plotted a heatmap. The heatmap showed that these parameters have both positive and negative correlations, as well as no correlation. It can be seen that the clinical parameters of mycoplasma pneumonia in children after the COVID-19 epidemic are positively or negatively correlated with each other.

Conclusion

In summary, our study suggests that after the COVID-19 epidemic, the clinical parameters of mycoplasma pneumonia in children have changed to some extent, mainly in serum protein, coagulation indicators and platelets, while the clinical parameters of mycoplasma pneumonia in children before the COVID-19 epidemic have relatively little change. Thus, the change may be a cause of significant serious conditions. That is because the clinical symptoms of mycoplasma pneumonia in children in Chengdu after the COVID-19 epidemic are more serious than those before the epidemic, and the epidemic duration is longer.

Acknowledgements

This study was supported by grants from the Chengdu Municipal Health Commission (No.2024079).

Author contributions

Zhou Fangye wrote the main manuscript text and Yang Sen and Zhang Wenchang prepared figures and tables, Huang Min collate datas.All authors reviewed the manuscript.

Data availability

The datasets used and/or analysed during the current study available from the corresponding author on reasonable request.

Declarations

Competing interests

The authors declare no competing interests.

Publisher’s note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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