Targeted next-generation sequencing reveals pathogen spectrum, drug resistance characteristics, and clinical determinants in children with community-acquired pneumonia
Original Article

Targeted next-generation sequencing reveals pathogen spectrum, drug resistance characteristics, and clinical determinants in children with community-acquired pneumonia

Pei-Pei Cai#, Dong Shen#, Ru-Hong Yan, Jiang-Tao Wen, Chang-Song Zhang, Bei Chen

Department of Clinical Laboratory, Suzhou Hospital, Affiliated Hospital of Medical School, Nanjing University, Suzhou, China

Contributions: (I) Conception and design: RH Yan; (II) Administrative support: CS Zhang; (III) Provision of study materials or patients: D Shen, JT Wen; (IV) Collection and assembly of data: PP Cai; (V) Data analysis and interpretation: B Chen; (VI) Manuscript writing: All authors; (VII) Final approval of manuscript: All authors.

#These authors contributed equally to this work.

Correspondence to: Bei Chen, MSc; Chang-Song Zhang, PhD. Department of Clinical Laboratory, Suzhou Hospital, Affiliated Hospital of Medical School, Nanjing University, No.1 Lijiang Road, Suzhou 215153, China. Email: Cb_7224@163.com; hbzcs@126.com.

Background: This study aimed to apply targeted next-generation sequencing (tNGS) to analyze the pathogen distribution in children with acute respiratory tract infections (ARTIs) in our region, compare the diagnostic performance of tNGS with that of the rapid Mycoplasma pneumoniae (MP) immunoglobulin M (IgM) antibody test, and investigate the clinical characteristics of MP infection, the impact of macrolide resistance genes on disease severity, factors associated with the need for bronchoalveolar lavage (BAL), and the clinical relevance of tetracycline use. Our findings are intended to provide a scientific basis for precise diagnosis and rational antimicrobial therapy in pediatric respiratory infections.

Methods: Blood parameters, including white blood cell (WBC) count, neutrophil percentage (Neut%), high-sensitivity C-reactive protein (hs-CRP), procalcitonin (PCT), and MP-IgM, were collected from pediatric patients aged 3 months to 13 years [median 7 years (interquartile range, IQR: 4–8 years)]. A retrospective analysis was performed by integrating these laboratory findings with oropharyngeal swab tNGS results, clinical data, and medication records.

Results: Viruses were the most frequently detected pathogens in children with ARTIs, accounting for 70.57% of cases. WBC count showed statistically significant differences in assessing infection types among children aged >6 years. Among MP-IgM (colloidal gold assay)-positive cases, 53.90% tested negative for MP by tNGS. The overall MP detection rate was 32.20%, with a macrolide resistance gene detection rate of 86.3%; all resistance mutations occurred at the A2063G site of the 23S rRNA gene. The MP-positive group more frequently presented with lobar pneumonia (54.21% vs. 7.59%), longer fever duration (5.25 vs. 4.00 days), and older age (7 vs. 5 years). The MP-negative group had higher rates of bilateral lung involvement (70.89% vs. 42.06%), viral detection (86.10% vs. 46.73%), and wheezing (11.39% vs. 2.80%). Tetracycline therapy did not significantly improve clinical outcomes in MP-infected children. Neut%, lobar pneumonia, use of cephalosporins, and intravenous immunoglobulin (IVIG) were independent predictors for BAL requirement. The presence of resistance genes was not associated with more severe outcomes, whereas MP positivity and lobar pneumonia were identified as risk factors for disease progression.

Conclusions: Age, fever duration, and lobar pneumonia may assist in the assessment of MP infection. MP-IgM (colloidal gold assay) results should be interpreted in conjunction with other clinical indicators. The use of tetracyclines for MP infection requires careful benefit-risk evaluation. Cephalosporin use was associated with a lower likelihood of BAL requirement, whereas a higher Neut% and the presence of lobar pneumonia were associated with a higher likelihood of BAL requirement.

Keywords: Mycoplasma pneumoniae (MP); macrolide resistance; targeted next-generation sequencing (tNGS); bronchoalveolar lavage (BAL)


Submitted Feb 25, 2026. Accepted for publication Apr 10, 2026. Published online May 26, 2026.

doi: 10.21037/tp-2026-1-0177


Highlight box

Key findings

• This oropharyngeal swab targeted next-generation sequencing (tNGS) study in 472 children with acute respiratory tract infections found viruses dominated (70.57% of detections). The Mycoplasma pneumoniae immunoglobulin M (MP-IgM) colloidal gold assay showed 53.90% discordance with tNGS. Macrolide resistance was detected in 86.3% of MP cases (all A2063G mutation), but tetracycline therapy did not improve clinical outcomes in children ≥8 years. Higher neutrophil percentage (Neut%), lobar pneumonia, and intravenous immunoglobulin use independently predicted bronchoalveolar lavage (BAL) requirement, while cephalosporin use reduced BAL likelihood.

What is known and what is new?

• MP is a leading cause of pediatric community-acquired pneumonia (CAP) in China with rising macrolide resistance, but whether resistance genes drive severity or tetracyclines provide real benefit remains unclear. tNGS detects pathogens and resistance genes, but pediatric upper respiratory tNGS data are limited.

• This study provides real-world evidence that positive MP-IgM warrants caution—over half were tNGS-negative. Tetracyclines did not shorten fever duration, hospital stay, or reduce severity in children ≥8 years with resistant MP. A predictive model (91.9% accuracy) identified independent BAL predictors, offering a practical intervention guide.

What is the implication, and what should change now?

• The lack of tetracycline benefit despite high macrolide resistance challenges current second-line strategies and calls for prospective trials. The marked serology-tNGS discordance means MP-IgM results should be weighed with other clinical clues before macrolides. Early risk stratification should rely on Neut%, lobar pneumonia, and other readily available predictors. Local guidelines should incorporate tNGS-based resistance data; routine tNGS may guide personalized therapy and avoid unnecessary BAL or antibiotic exposure in selected pediatric CAP patients.


Introduction

Acute respiratory tract infections (ARTIs) represent a major cause of morbidity and mortality among young children in developing countries. These infections are highly contagious, widely prevalent, and pose substantial risks to children, the elderly, and immunocompromised individuals (1). Community-acquired pneumonia (CAP), defined as an acute infection of the lung parenchyma acquired outside hospitals or healthcare settings, is one of the leading causes of hospitalization and death worldwide (2) and remains a major contributor to childhood mortality in developing regions. The diagnosis of CAP is challenging because its clinical presentation varies with age and is often nonspecific in young children.

Mycoplasma pneumoniae (MP) is a prominent pathogen, accounting for approximately 20–40% of CAP cases. Some children with M. pneumoniae pneumonia (MPP) progress to severe disease, and the incidence of severe MPP has been increasing in recent years (3). Moreover, MPP is difficult to distinguish from bacterial pneumonia based solely on clinical and radiological findings (4). With the widespread use of macrolide antibiotics, resistance rates in MPP have risen steadily (5); however, whether resistant strains lead to more severe disease remains debated.

Targeted next-generation sequencing (tNGS) employs a highly multiplexed polymerase chain reaction (PCR)-based library preparation system to enrich and amplify target sequences, followed by high-throughput sequencing for simultaneous detection of amplified products. This approach enables rapid and objective identification of a broad range of pathogens, including bacteria, fungi, viruses, and atypical organisms, while also enabling the detection of resistance genes, thereby facilitating early clinical recognition of potential pathogens. Compared with metagenomic NGS (mNGS), tNGS offers advantages in speed, sensitivity, and specificity (6) and can identify genetic variants (7). Its application in clinical diagnosis and management has expanded considerably in recent years (8); however, studies evaluating tNGS for respiratory pathogen detection in oropharyngeal swabs from children remain limited.

This study utilized tNGS to analyze oropharyngeal swab specimens from children with ARTIs, aiming to characterize the pathogen distribution, clinical features of MPP, factors influencing bronchoalveolar lavage (BAL), the impact of macrolide resistance on disease severity, and the effect of tetracyclines on outcomes in MPP. The results are intended to provide data supporting infection control strategies in pediatric populations. We present this article in accordance with the STROBE reporting checklist (available at https://tp.amegroups.com/article/view/10.21037/tp-2026-1-0177/rc).


Methods

Study population

Clinical data were collected from 472 children with ARTIs who underwent tNGS testing between November 2023 and February 2025, which were retrieved from the laboratory information system of Nanjing University Medical School Affiliated Suzhou Hospital (Figure 1). This retrospective study was approved by the Ethics Committee of Suzhou Hospital, Affiliated Hospital of Medical School, Nanjing University(Suzhou Science and Technology Town Hospital) (approval No. IRB2025061). Patient data were anonymized. This study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the parents of all patients.

Figure 1 Flow chart of sample screening. A total of 472 patients were enrolled for pathogen distribution analysis based on tNGS testing. Among them, 427 pediatric patients were included in the study investigating infection types. A total of 216 patients with complete MP-IgM (colloidal gold assay) results were used to compare detection rates. After applying the exclusion criteria, 186 patients comprised the final cohort for clinical comparisons (MP-positive vs. MP-negative; mild vs. severe disease) and treatment efficacy analyses (BAL, tetracycline antibiotics). A separate subset of 41 patients aged ≥8 years with detected MP drug resistance genes was analyzed for resistance patterns. BAL, bronchoalveolar lavage; CAP, community-acquired pneumonia; hsCRP, high-sensitivity C-reactive protein; IgM, immunoglobulin M; MP, Mycoplasma pneumoniae; Neut%, neutrophil percentage; tNGS, targeted next-generation sequencing; WBC, white blood cell.

Inclusion and exclusion criteria

The inclusion criteria were as follows: (I) meeting the diagnostic criteria for ARTIs and CAP; (II) age ≤13 years; and (III) tNGS sample collected on the day of admission. CAP diagnosis was established according to the 2019 Guidelines for the Diagnosis and Treatment of Community-Acquired Pneumonia. The exclusion criteria were as follows: (I) underlying conditions such as asthma, chronic cardiopulmonary disease, rheumatologic disorders, or immunodeficiency; (II) treatment at our hospital within the preceding 3 months, especially if the MP-immunoglobulin M (IgM) (colloidal gold assay) result was positive; (III) incomplete clinical data; and (IV) use of macrolide or tetracycline antibiotics before enrollment due to prolonged cough.

Data collection and grouping

Demographic and clinical parameters recorded included age, sex, white blood cell (WBC) count, neutrophil percentage (Neut%), high-sensitivity C-reactive protein (hs-CRP), pathogen profile, macrolide resistance genes, and MP-IgM (colloidal gold assay) results. For hospitalized children, additional data were collected, including procalcitonin (PCT), clinical presentation (pneumonia type, lung involvement, lung auscultation, wheezing), hospital stay, fever duration, medication use [macrolides, tetracyclines, cephalosporins, penicillins, corticosteroids, and intravenous immunoglobulin (IVIG)], and BAL therapy. Subjects who tested positive for MP by tNGS were assigned to the MP-detected group, whereas those with negative tNGS results were assigned to the MP-non-detected group. Detection of a single pathogen was classified as monoinfection, while detection of more than one pathogen was classified as co-infection. Patients who met any of the following criteria were assigned to the severe group: administration of IVIG, requirement of BAL, presence of pulmonary consolidation, presence of wheezing, or fever lasting ≥7 days. Patients who met none of these criteria were assigned to the mild group. Based on the pathogenicity classification provided in the tNGS report, the detected microorganisms were classified as pathogenic, opportunistic, or colonizing flora.

Laboratory methods

MP-IgM (colloidal gold assay)

Fingertip capillary blood was tested using colloidal gold kits (Beijing Innover and Beijing Beier Biotechnology Co., Ltd.), and results were reported within 20 minutes.

Routine laboratory tests

WBC, Neut%, and hs-CRP were measured using a Mindray BC-7500 hematology analyzer. PCT was determined by chemiluminescence (Changguang Huayi).

tNGS

Oropharyngeal swab samples were sent to KingMed Diagnostics (Guangzhou) for tNGS analysis. Data analysis was performed using an independently developed pathogen bioinformatics pipeline (Guangzhou King-Key Biotechnology Co., Ltd.). Quality thresholds included Q30 >75%, minimum raw reads ≥50k, and internal control normalized reads ≥200 or target pathogen normalized reads ≥3,000. A pathogen was considered positive if at least one target showed normalized reads ≥20. Macrolide resistance was defined by detection of known resistance mutations (A2063G, A2064G, A2067G, C2617G) in the MP 23S rRNA gene.

Statistical analysis

All data were analyzed using SPSS version 22.0 and GraphPad Prism version 10. Continuous variables with skewed distributions were expressed as median [interquartile range (IQR)] and compared between two groups using the Mann-Whitney U test. Categorical variables were described as percentages and analyzed using the chi-square test. Binary logistic regression analysis was performed to identify independent factors influencing the outcome variable. Variables with statistically significant differences in univariate analysis were entered into the model as independent variables, and potential confounders were adjusted for in the regression model. A two-tailed P value of less than 0.05 was considered statistically significant.


Results

Pathogen distribution

Among the 472 children with ARTIs [age range: 3 months to 13 years; median 7 years (IQR 4–8 years); 222 males, 250 females], there was no statistically significant difference in age between males and females (P=0.89). A total of 1,182 pathogens were detected, including 501 viruses (42%, 16 types), 528 bacteria (45%, 12 species), and 153 atypical pathogens (13%, 2 species). The most frequently detected agents were adenovirus (116/1,182) among viruses, Haemophilus influenzae (202/1,182) among bacteria, and MP (152/1,182) among atypical pathogens. Of these, 683 were classified as pathogenic, 414 as opportunistic, and 85 as colonizers (Figure 2).

Figure 2 Pathogen detection results. (A) Distribution of pathogen types (bacteria, viruses, and atypical pathogens) among the 1,182 detected pathogens. (B) Classification of all pathogens based on pathogenic potential. (C) Proportional composition of individual pathogens within the atypical pathogen category. (D) Relative abundance of specific bacterial pathogens within the bacterial category. (E) Relative abundance of specific viral pathogens within the viral group; EB, Epstein-Barr.

Differences in WBC, Neut%, and hs-CRP levels among different types of infections

After excluding colonizers flora (reported as normal respiratory flora), 427 children with complete data on WBC count, Neut%, and hs-CRP were stratified by age. Co-infection accounted for 74.94% of cases. A significant difference in WBC count among infection types was observed only in the 6–13 years age group (P<0.05), with higher values noted in co-infected children (Table 1).

Table 1

Comparison of WBC, Neut% and hsCRP in different age subgroups with different types of infection

Age groups Infection indicators Monoinfection (N=107) Co-infections (N=320) P
6–13 years old (N=271) WBC 7.91 (6.04, 9.96) 9.26 (6.79, 12.52) 0.006
Neut% 63.35 (54.48, 72.40) 67.60 (53.70, 76.30) 0.14
hsCRP 8.28 (3.44, 19.58) 8.68 (2.04, 25.71) 0.82
2–5.9 years old (N=119) WBC 9.59 (6.84, 12.38) 8.72 (6.70, 11.82) 0.47
Neut% 55.85 (41.90, 70.80) 63.70 (50.00, 72.90) 0.36
hsCRP 10.07 (2.47, 30.12) 10.95 (1.90, 24.50) 0.42
<2 years old (N=37) WBC 8.20 (6.11, /) 7.93 (6.20, 10.35) 0.78
Neut% 39.70 (20.30, /) 38.6 (28.28, 55.10) 0.91
hsCRP 7.05 (0.2, /) 3.63 (0.92, 8.48) 0.89

Data are presented as median (interquartile range). WBC measurements of 109/L and mg/L for hsCRP, data on colonizing bacteria have been excluded. “/” means high percentiles (75th) could not be calculated for the mono-infection group due to the small sample size. hsCRP, high-sensitivity C-reactive protein; Neut%, neutrophil percentage; WBC, white blood cell count.

Comparison between tNGS and MP-IgM (colloidal gold assay)

Among the 216 children tested using both methods, paired chi-square analysis revealed a statistically significant difference in MP detection rates (P<0.001; Table 2).

Table 2

Comparison of MP detection rates between tNGS and MP-IgM colloidal gold immunoassay

tNGS MP-IgM colloidal gold immunoassay Total P
Negative Positive
Negative 48 76 124 <0.001
Positive 27 65 92
Total 75 141 216

IgM, immunoglobulin M; MP, Mycoplasma pneumoniae; tNGS, targeted next-generation sequencing.

Comparative analysis of clinical features in patients with and without MP detection

MP was detected by tNGS in 152 of 472 children (32.20%); of these MP-positive children, 132 (86.30%) carried a macrolide resistance gene. From the 152 MP-positive and 320 MP-negative children, 186 with radiologically confirmed pneumonia and complete clinical data were further analyzed. Significant differences (P<0.05) were observed in age, viral co-detection, pneumonia type, lung involvement, wheezing, and fever duration. MP-positive children were older (median 7 vs. 5 years). Lobar pneumonia was predominantly associated with MP, accounting for 90.63% of lobar pneumonia cases in the MP-positive group. In contrast, bronchopneumonia was more common in MP-negative children (59.84%). MP-negative cases had higher rates of bilateral lung involvement (70.89% vs. 42.06% in MP-positive cases), viral co-detection (86.10% vs. 46.73%), and wheezing (75% of wheezing cases occurred in MP-negative children) (Table 3).

Table 3

Clinical characteristics of with and without MP detection

Clinical characteristics MP-detected (N=107) MP-non-detected (N=79) P
Gender 0.68
   Male 48 (44.86) 46 (58.20)
   Female 59 (55.14) 33 (41.80)
Virus detection <0.001
   Yes 50 (46.73) 68 (86.08)
   No 57 (53.27) 11 (13.92)
Type of pneumonia <0.001
   Lobar pneumonia 58 (54.21) 6 (7.59)
   Bronchopneumonia 49 (45.79) 73 (92.41)
Extent of lung involvement <0.001
   Bilateral infiltrates 45 (42.06) 56 (70.89)
   Unilateral infiltrates 62 (57.94) 23 (29.11)
Lung consolidation 0.24
   Yes 5 (4.67) 1 (1.27)
   No 102 (95.33) 78 (98.73)
Rales 0.43
   Yes 75 (70.09) 51 (64.56)
   No 32 (29.91) 28 (35.44)
Wheezing 0.02
   Yes 3 (2.80) 9 (11.39)
   No 104 (97.20) 70 (88.61)
Fever duration (days) 5 (3.0, 7.0) 4 (2.0, 6.0) 0.002
Age (years) 7 (6.0, 9.0) 5 (3.0, 8.0) <0.001
WBC (×109/L) 7.40 (6.05, 10.78) 8.76 (6.76, 10.58) 0.16
Neut% (%) 65.00 (55.90, 73.40) 62.50 (40.80, 74.80) 0.16
hsCRP (mg/L) 8.91 (4.34, 22.03) 8.94 (2.17, 23.13) 0.80
PCT (ng/mL) 0.08 (0.05, 0.14) 0.07 (0.05, 0.18) 0.61

Data are presented as number (%) or median (interquartile range). hsCRP, high-sensitivity C-reactive protein; MP, Mycoplasma pneumoniae; Neut%, neutrophil percentage; PCT, procalcitonin; WBC, white blood cell count.

Impact of tetracyclines on clinical outcomes

Among 41 children aged ≥8 years with tNGS-confirmed macrolide resistance genes in MP, no significant differences were observed in fever duration, hospital stay, or severe disease classification between those who received tetracyclines and those who did not (P>0.05; Table 4).

Table 4

Impact of tetracycline antibiotics on clinical outcomes

Clinical characteristics Tetracyclines treatment (N=26) Without tetracyclines treatment (N=15) P
Age (years) 10 (9, 10.25) 10 (9, 10) 0.65
Fever duration (days) 5 (3.5, 7.25) 6 (3.0, 7.0) 0.89
Length of hospital stay (days) 7 (6.0, 8.0) 6 (5.0, 8.0) 0.36
Severe disease 14 (53.85) 6 (40.00) 0.39

Data are presented as number (%) or median (interquartile range).

Factors associated with BAL

Comparison of 186 children with CAP (with vs. without BAL) revealed significant differences (P<0.05) in pneumonia type, use of cephalosporins, tetracyclines, IVIG, Neut%, and fever duration. BAL-treated children were more likely to have lobar pneumonia, higher Neut% (73.00% vs. 63.45%), longer fever duration (median 6 vs. 5 days), and greater use of tetracyclines and IVIG, but lower use of cephalosporins (Table 5). A binary logistic regression analysis was performed with BAL as the dependent variable (BAL performed =1, not performed =0). Variables that showed statistically significant differences in Table 5 were entered as independent variables, including lobar pneumonia, tetracycline use, cephalosporin use, IVIG use, Neut%, and fever duration. In addition, potential confounders including sex, age, and co-infection status were adjusted for in the model. The results showed that Neut%, lobar pneumonia, cephalosporin use, and IVIG use were independent factors associated with BAL (P<0.05). The regression model demonstrated satisfactory goodness-of-fit (Hosmer-Lemeshow test, P>0.99), and the overall prediction accuracy of the model was 91.9% (Figure 3).

Table 5

Factors associated with therapeutic bronchoalveolar lavage

Clinical characteristics Bronchoalveolar lavage (N=18) Without bronchoalveolar lavage (N=168) P
Male 8 (9.90) 73 (90.10) 0.94
Female 10 (9.50) 95 (90.50)
Co-infection 11 (61.10) 118 (70.20) 0.43
Lobar pneumonia 16 (88.89) 48 (28.57) <0.001
Macrolides 16 (88.89) 142 (84.52) >0.99
Tetracyclines 9 (50.00) 37 (22.02) 0.02
Cephalosporins 13 (72.22) 152 (90.48) 0.04
Penicillins 7 (38.89) 33 (19.64) 0.07
Corticosteroid 18 (100.0) 154 (91.67) 0.37
IVIG 3 (16.67) 2 (1.19) 0.007
Unilateral infiltrates 10 (55.56) 75 (44.64) 0.38
Lung consolidation 2 (11.11) 4 (2.38) 0.11
Rale 12 (66.67) 114 (67.86) 0.92
Wheezing 0 (0.0) 12 (7.14) 0.61
Age (years) 7 (5.75, 10.00) 7 (4.00, 9.00) 0.10
WBC (×109/L) 6.88 (5.29, 9.49) 8.21 (6.53, 10.79) 0.15
Neut% (%) 73.00 (65.73, 80.58) 63.45 (51.83, 72.38) 0.006
hsCRP (mg/L) 11.46 (5.51, 39.90) 8.53 (2.90, 22.23) 0.22
PCT (ng/mL) 0.10 (0.05, 0.25) 0.08 (0.05, 0.15) 0.44
Fever duration (days) 6 (4.0, 9.0) 5 (3.0, 7.0) 0.03

Data are presented as number (%) or median (interquartile range). hsCRP, high-sensitivity C-reactive protein; IVIG, intravenous immunoglobulin; Neut%, neutrophil percentage; PCT, procalcitonin; WBC, white blood cell count.

Figure 3 Independent influencing factors of BAL. Binary logistic regression was performed on factors with P<0.05 from Table 5 (lobar pneumonia, tetracycline use, cephalosporin use, IVIG, Neut%, and fever duration) to identify independent predictors for BAL. Neut%, the presence of lobar pneumonia, and the use of IVIG were identified as risk factors associated with an increased need for BAL. In contrast, cephalosporin use was associated with a reduced likelihood of BAL requirement. Among children with lobar pneumonia, 16 underwent BAL. BAL, bronchoalveolar lavage; CI, confidence interval; IVIG, intravenous immunoglobulin; Neut%, neutrophil percentage; OR, odds ratio.

Comparison of clinical characteristics between severe and mild groups

A total of 186 children with CAP were stratified into severe and mild groups. Severe CAP (as defined above) was associated with higher MP detection (68.49% vs. 50.44%) and more frequent lobar pneumonia (45.21% vs. 27.43%) compared with mild cases (P<0.05; Table 6).

Table 6

Comparison between the severe group and the mild group

Clinical characteristics Severe group (N=73) Mild group (N=113) P
MP detected 50 (68.49) 57 (50.44) 0.02
Carry resistance genes 43 (86.0) 50 (87.7) 0.79
Mixed infections 51 (69.9) 81 (71.7) 0.79
Lobar pneumonia 33 (45.21) 31 (27.43) 0.01
Bilateral infiltrates 37 (50.7) 64 (56.6) 0.43
Rale 53 (72.6) 73 (64.6) 0.25
Age (years) 7 (3.5, 9.0) 7 (4.5, 9.0) 0.78
WBC (×109/L) 8.05 (6.11, 10.31) 8.2 (6.34, 11.0) 0.48
Neut% (%) 65 (53.75, 73.9) 64.7 (51.3, 72.9) 0.51
hsCRP (mg/L) 10.26 (4.41, 20.58) 8.46 (2.94, 23.66) 0.91
PCT (ng/mL) 0.079 (0.06, 0.13) 0.078 (0.05, 0.16) 0.88

Data are presented as number (%) or median (interquartile range). hsCRP, high-sensitivity C-reactive protein; MP, Mycoplasma pneumoniae; Neut%, neutrophil percentage; PCT, procalcitonin; WBC, white blood cell count.


Discussion

Upper and lower respiratory tract infections contribute substantially to childhood morbidity and mortality (9); therefore, early pathogen identification and severity assessment are crucial. Previous studies have suggested good concordance between upper and lower respiratory pathogen profiles (10,11). Using tNGS of oropharyngeal swabs, we found that viruses were the most common pathogens in pediatric ARTIs, with pathogenic viruses accounting for 70.57% of viral detections, followed by bacteria. It is recognized that viruses can enhance bacterial colonization of the upper respiratory tract (12), which may subsequently facilitate bacterial invasion of the lungs (13). Accordingly, early antiviral therapy should be emphasized.

Co-infection is often associated with more severe disease progression (14); therefore, early assessment of infection type is of considerable importance. WBC count, Neut%, and hs-CRP are basic indicators used to differentiate bacterial infection and evaluate disease severity. In the present study, no significant differences in Neut% or hs-CRP were observed across infection types in any age group. In contrast, WBC count demonstrated discriminative ability only in children aged 6–13 years, suggesting that this parameter retains clinical value in this older subgroup.

The MP-IgM colloidal gold assay is a rapid and convenient method commonly used for clinical screening of MP. In the present study, 53.90% of patients who tested positive by MP-IgM were negative by tNGS. This discordance may lead to unnecessary use of macrolide antibiotics. Given the absence of a reference standard method for MP detection in this study, the comparative diagnostic performance of the two methods could not be reliably determined, and conclusions regarding their diagnostic accuracy are therefore limited. Consequently, a positive MP-IgM result should be interpreted with caution, and antibiotic therapy should be initiated only after comprehensive evaluation in conjunction with other clinical indicators and manifestations. Macrolide resistance in MP remains a growing concern (15). In this study, the observed resistance rate (86.3%) was lower than that reported by Xu et al. [96% (16)] but higher than that reported by Zhan et al. [64.6% (17)]. All resistant strains carried 23S rRNA mutations, exclusively at the A2063G site, which is consistent with a 2023 surveillance report from Beijing (18).

Previous studies have suggested that viral infection may increase susceptibility to MP (19). Interestingly, in the present study, the MP-negative group had higher rates of viral detection. This finding may be explained by a stronger immune response triggered by MP infection (20), which could interfere with or suppress viral co-infection. MP often presents as lobar pneumonia (21), a finding that is consistent with the present results. MP-positive children had longer fever duration (5.25 vs. 4.00 days), whereas MP-negative children more frequently presented with bronchopneumonia. Notably, bilateral infiltrates and wheezing were more common in the MP-negative group, which consisted of younger children (median age 5 years) with a high rate of bacterial-viral co-infection (94.14%). It is known that viruses promote upper respiratory bacterial colonization (22), and such colonization has been linked to lower respiratory tract infections in young children (11). Therefore, we speculate that secondary bacterial infection may contribute to bilateral infiltrates and wheezing in MP-negative patients. These clinical distinctions may assist clinicians in assessing the likelihood of MP infection.

The use of tetracyclines as second-line agents for macrolide-resistant MPP remains controversial. Some authors recommend switching to doxycycline if fever persists for more than 48 hours after macrolide therapy (23), whereas others advocate reserving alternative antibiotics for severe cases (24). In addition, Cai et al. (25) raised concerns regarding the dermatological effects of doxycycline in children. In the present study, no significant impact of tetracyclines on clinical outcomes was observed, which aligns with the findings of Ha et al. (26). Therefore, for patients showing a slow response to macrolides, further evaluation and individualized management are warranted.

BAL is an effective intervention for severe or refractory pneumonia. The higher Neut% observed in the BAL group (73.00% vs. 63.45%) suggests an enhanced neutrophil-driven immune response, which is consistent with the findings of Zhu et al. (20). In the present cohort, all children who received IVIG and 88.89% of those who underwent BAL were MP-positive. Regression analysis revealed that children with lobar pneumonia had 43.8-fold higher odds of requiring BAL, and IVIG use increased the odds by 18.7-fold. In contrast, cephalosporin use was associated with a reduced likelihood of BAL requirement. The predictive model demonstrated 91.9% accuracy, providing a useful tool for individualized treatment planning.

Notably, the presence of resistance genes did not correlate with more severe disease, whereas MP positivity and lobar pneumonia were identified as independent risk factors for severe CAP, underscoring the need for close monitoring and active management in these patients. In the present study, 46.73% (50/107) of MPP cases had viral co-detection, which is higher than the 27.27% reported by Zhao et al. (27) but lower than the 56.07% reported by Zhou et al. (23), indicating that viruses continue to pose a concurrent threat in MP infections.

Limitations

Several limitations of this study should be acknowledged. First, the single-center retrospective design and the relatively small hospitalized cohort size may limit the generalizability of the findings. Second, the use of oropharyngeal swab samples represents a limitation, as microbial detection in the upper respiratory tract cannot reliably distinguish true infection from colonization. Although the pathogen classification provided in the test report (definite pathogens, opportunistic pathogens, or colonizing flora) was adopted to mitigate this concern, the potential for misclassification remains. Therefore, larger multicenter prospective studies using lower respiratory tract specimens are warranted to validate these findings and enable a more accurate assessment of infection status. Finally, future work should also explore the mechanisms underlying MP-viral co-infection to further guide precision medicine in pediatric respiratory infections.


Conclusions

In conclusion, tNGS of oropharyngeal swabs is effective for pathogen and macrolide resistance detection in pediatric ARTIs. Viruses are the predominant pathogens, and co-infection is common. The MP-IgM colloidal gold assay shows considerable discordance with tNGS, warranting cautious interpretation. Tetracycline therapy did not improve outcomes in children aged ≥8 years with macrolide-resistant MP, challenging current second-line practices. MP-positive children typically present with lobar pneumonia, older age, and longer fever duration, whereas MP-negative children more often have bilateral infiltrates, wheezing, and viral co-detection. Neut%, lobar pneumonia, and IVIG use independently predicted BAL requirement, while cephalosporin use was associated with lower BAL likelihood. Macrolide resistance genes did not correlate with disease severity, whereas MP positivity and lobar pneumonia were independent risk factors for severe CAP. Prospective multicenter studies using lower respiratory tract specimens are needed to validate these findings and optimize antimicrobial stewardship.


Acknowledgments

None.


Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://tp.amegroups.com/article/view/10.21037/tp-2026-1-0177/rc

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Funding: This work was supported by The Science and Technology Program of Suzhou (No. SKY2021032).

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://tp.amegroups.com/article/view/10.21037/tp-2026-1-0177/coif). R.H.Y. reports funding support from The Science and Technology Program of Suzhou (No. SKY2021032). The other authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. This study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the Ethics Committee of Suzhou Hospital, Affiliated Hospital of Medical School, Nanjing University (Suzhou Science and Technology Town Hospital) (approval No. IRB2025061). Written informed consent was obtained from the parents of all patients.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.


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Cite this article as: Cai PP, Shen D, Yan RH, Wen JT, Zhang CS, Chen B. Targeted next-generation sequencing reveals pathogen spectrum, drug resistance characteristics, and clinical determinants in children with community-acquired pneumonia. Transl Pediatr 2026;15(5):178. doi: 10.21037/tp-2026-1-0177

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