Early Serologic Diagnosis of Mycoplasma pneumoniae Pneumonia: An Observational Study on Changes in Titers of Specific-IgM Antibodies and Cold Agglutinins

Risk Prediction Model for Necrotizing Pneumonia in Children with Mycoplasma pneumoniae Pneumonia

Objective

To analyze the predictive factors for necrotizing pneumonia (NP) in children with Mycoplasma pneumoniae pneumonia (MPP) and construct a prediction model.

Methods

The clinical data with MPP at the Children's Hospital of Kunming Medical University from January 2014 to November 2022 were retrospectively analyzed. Eighty-four children with MPP who developed NP were divided into the necrotizing group, and 168 children who did not develop NP were divided into the non-necrotizing group by propensity-score matching. LASSO regression was used to select the optimal factors, and multivariate logistic regression analysis was used to establish a clinical prediction model. The receiver operating characteristic (ROC) curve and calibration curve were used to evaluate the discrimination and calibration of the nomogram. Clinical decision curve analysis was used to evaluate the clinical predictive value.

Results

LASSO regression analysis showed that bacterial co-infection, chest pain, LDH, CRP, duration of fever, and D-dimer were the influencing factors for NP in children with MPP (P < 0.05). The results of ROC analysis showed that the AUC of the prediction model established in this study for predicting necrotizing MPP was 0.870 (95% CI: 0.813-0.927, P < 0.001) in the training set and 0.843 (95% CI: 0.757-0.930, P < 0.001) in the validation set. The Bootstrap repeated sampling for 1000 times was used for internal validation, and the calibration curve showed that the model had good consistency. The Hosmer-Lemeshow test showed that the predicted probability of the model had a good fit with the actual probability in the training set and the validation set (P values of 0.366 and 0.667, respectively). The clinical decision curve showed that the model had good clinical application value.

Conclusion

The prediction model based on bacterial co-infection, chest pain, LDH, CRP, fever duration, and D-dimer has a good predictive value for necrotizing MPP.

Poor accuracy of single serological IgM tests in children with suspected acute Mycoplasma pneumoniae infection in Guangzhou, China

Introduction. Early and accurate diagnosis of Mycoplasma pneumoniae (MP) infection of children with pneumonia is at the core of treatment in clinical practice.Gap Statement. Serological immunoglobulin M (IgM) tests for MP infection of children in south China have been rarely described.Aim. To assess the diagnostic performance and clinical application of serodiagnosis of MP infection in paediatric pneumonia patients.Methodology. Serum samples from 144 children diagnosed with MP pneumonia were subjected to a particle agglutination (PA)-based IgM assay. Meanwhile, we used an established suspension array as the reference standard method for the detection of MP DNA in bronchoalveolar lavage fluid (BALF) from all patients to assess the reliability of serological assays.Results. When running immunological testing in single serum samples, 80.6 %(79/98) of cases were diagnosed with MP infection, whereas only 55 (56.1 %) cases were positive in MP DNA analysis. Furthermore, single serum tests for IgM during acute MP infection resulted in 85.5 % (47/55) sensitivity and 25.6 % (11/43) specificity. Nevertheless, immunological testing and MP DNA analysis yielded the same results when paired sera were available for MP IgM antibody testing.Conclusion. Paired serological IgM assays are necessary for the determination of an acute MP infection, whereas single serological IgM testing is unreliable. Moreover, even a short interval of two MP serological tests works well.

The molecular characteristics, diagnosis, and treatment of macrolide-resistant Mycoplasma pneumoniae in children

The purpose of this study is to review the molecular characteristics, the diagnosis, and treatment of the widespread infection of macrolide-resistant Mycoplasma pneumoniae (M. pneumoniae; MRMP) in children, thus providing a better knowledge of this infection and presenting the associated problems. Single point mutations in the V region of the 23S rRNA gene of M. pneumoniae genome are associated with macrolide resistance. P1-1, MLVA4-5-7-2, and ST3 are usually the predominated genetic types in the M. pneumoniae epidemics. The short-term two times serological IgM (or together with IgG) test in the acute stage can be used for confirmation. Combined serological testing and PCR might be a more prudent method to reduce macrolide consumption and antibiotic selective pressure in a clinical setting. Molecular methods for the detection of single-nucleotide mutations in the V region of the 23S rRNA gene can be used for the diagnosis of MRMP. The routine use of macrolide for the treatment of macrolide-sensitive Mycoplasma pneumoniae (MSMP) infections can get good effect, but the effects are limited for severe MRMP infections. Additional corticosteroids may be required for the treatment of severe MRMP infections in children in China during the era of MRMP.

Analytical Studies of Antimicrobial Peptides as Diagnostic Biomarkers for the Detection of Bacterial and Viral Pneumonia

Pneumonia remains one of the leading causes of infectious mortality and significant economic losses among our growing population. The lack of specific biomarkers for correct and timely diagnosis to detect patients’ status is a bane towards initiating a proper treatment plan for the disease; thus, current biomarkers cannot distinguish between pneumonia and other associated conditions such as atherosclerotic plaques and human immunodeficiency virus (HIV). Antimicrobial peptides (AMPs) are potential candidates for detecting numerous illnesses due to their compensatory roles as theranostic molecules. This research sought to generate specific data for parental AMPs to identify viral and bacterial pneumonia pathogens using in silico technology. The parental antimicrobial peptides (AMPs) used in this work were AMPs discovered in our previous in silico analyses using the HMMER algorithm, which were used to generate derivative (mutated) AMPs that would bind with greater affinity, in order to detect the bacterial and viral receptors using an in silico site-directed mutagenesis approach. These AMPs’ 3D structures were subsequently predicted and docked against receptor proteins. The result shows putative AMPs with the potential capacity to detect pneumonia caused by these pathogens through their binding precision with high sensitivity, accuracy, and specificity for possible use in point-of-care diagnosis. These peptides’ tendency to detect receptor proteins of viral and bacterial pneumonia with precision justifies their use for differential diagnostics, in an attempt to reduce the problems of indiscriminate overuse, toxicity due to the wrong prescription, bacterial resistance, and the scarcity and high cost of existing pneumonia antibiotics.

Development and validation of a nomogram to predict plastic bronchitis in children with refractory Mycoplasma pneumoniae pneumonia

Background

Early identification of plastic bronchitis (PB) is of great importance and may aid in delivering appropriate treatment. This study aimed to develop and validate a nomogram for predicting PB in patients with refractory Mycoplasma pneumoniae pneumonia (RMPP).

Methods

A total of 547 consecutive children with RMPP who underwent fiberoptic bronchoscopy (FOB) intervention from January 2016 to June 2021 were enrolled in this study. Subsequently, 374 RMPP children (PB: 137, without PB: 237) from January 2016 to December 2019 were assigned to the development dataset to construct the nomogram to predict PB and 173 RMPP children from January 2020 to June 2021 were assigned to the validation dataset. The clinical, laboratory and radiological findings were screened using Least Absolute Shrinkage and Selection Operator (LASSO) regression and logistic regression was applied to construct a nomogram. The performance of the nomogram was evaluated by discrimination, calibration and clinical utility. Comparsion of ROC analysis and decision curve analysis (DCA) between nomogram and other models was performed to evaluate the discrimination ability and clinical utility.

Results

The development dataset included 374 patients with a mean age of 6.6 years and 185(49.5%) were men. The validation dataset included 173 patients and the mean age of the dataset was 6.7 years and 86 (49.7%) were men. From 26 potential predictors, LASSO regression identified 6 variables as significant predictive factors to construct the nomogram for predicting PB, including peak body temperature, neutrophil ratio (N%), platelet counts (PLT), interleukin-6 (IL-6), actic dehydrogenase (LDH) and pulmonary atelectasis. The nomogram showed good discrimination, calibration and clinical value. The mean AUC of the nomogram was 0.813 (95% CI 0.769–0.856) in the development dataset and 0.895 (95% CI 0.847–0.943) in the validation dataset. Through calibration plot and Hosmer–Lemeshow test, the predicted probability had a good consistency with actual probability both in the development dataset (P = 0.217) and validation dataset (P = 0.183), and DCA showed good clinical utility. ROC analysis indicated that the nomogram showed better discrimination ability compared with model of peak body temperature + pulmonary atelactsis and another model of N% + PLT + IL-6 + LDH, both in development dataset (AUC 0.813 vs 0.757 vs 0.754) and validation dataset (AUC 0.895 vs 0.789 vs 0.842).

Conclusions

In this study, a nomogram for predicting PB among RMPP patients was developed and validated. It performs well on discrimination ability, calibration ability and clinical value and may have the potential for the early identification of PB that will help physicians take timely intervention and appropriate management.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-022-02047-2.

Prediction Model for Severe Mycoplasma pneumoniae Pneumonia in Pediatric Patients by Admission Laboratory Indicators

OBJECTIVE

The purpose of this study was to develop a model for predicting severe Mycoplasma pneumoniae pneumonia (SMPP) in pediatric patients with Mycoplasma pneumoniae pneumonia (MPP) on admission by laboratory indicators.

METHODS

Pediatric patients with MPP from January 2019 to December 2020 in our hospital were enrolled in this study. SMPP was diagnosed according to guideline for diagnosis and treatment of community-acquired pneumonia in children (2019 version). Prediction model was developed according to the admission laboratory indicators. Receiver operating characteristic curve and Goodness-of-fit test were analyzed for the predictive value.

RESULTS

A total of 233 MPP patients were included in the study, with 121 males and 112 females, aged 4.541 (1-14) years. Among them, 84 (36.1%, 95% CI 29.9-42.6%) pediatric patients were diagnosed as SMPP. Some admission laboratory indicators (immunoglobulins M (IgM), eosinophil proportion, eosinophil count, hemoglobin, erythrocyte sedimentation rate (ESR), total protein, albumin and prealbumin) were found statistically different (p < 0.05) between non-SMPP group and SMPP group. Logistic regress analysis showed IgM, eosinophil proportion, eosinophil count, ESR and prealbumin were independent risk factors for SMPP. According to these five admission laboratory indicators, the prediction model for SMPP in pediatric patients was developed. The area under curve of the prediction model was 0.777, and the goodness-of-fit test showed that the predicted SMPP incidence by the model was consistent with the actual incidence (χ2 = 244.51, p = 0.203).

CONCLUSION

We developed a model for predicting SMPP in pediatric patients by admission laboratory indicators. This model has good discrimination and calibration, which provides a basis for the early identification SMPP on admission. However, this model should be validated by multicenter studies with large sample.

Clinical significance of respiratory virus coinfection in children with Mycoplasma pneumoniae pneumonia

BACKGROUND

The prevalence of refractory Mycoplasma pneumoniae (MP) pneumonia has been increasing. However, few studies have investigated the impact of respiratory virus coinfection in patients with MP pneumonia, and their results have been inconclusive. This study aimed to investigate the impact of respiratory virus coinfection in children hospitalized with MP pneumonia.

METHODS

This study enrolled 145 children hospitalized with MP pneumonia between May 2019 and March 2020. The patients were divided into two groups: the respiratory virus coinfection and non-coinfection groups. All the children underwent polymerase chain reaction testing for respiratory virus infection. Information on clinical, laboratory, and radiologic findings were obtained retrospectively via medical chart reviews.

RESULTS

Children in the respiratory virus coinfection group were younger than those in the non-coinfection group. Respiratory virus coinfection in children hospitalized with MP pneumonia was significantly associated with persistence of fever more than 6 days (adjusted odds ratio [aOR], 2.394; 95% confidence interval [95% CI], 1.172-4.892), severe pneumonia (aOR, 4.602; 95% CI, 1.154-18.353), and poor response to the stepwise approach for MP pneumonia (aOR, 4.354; 95% CI, 1.374-13.800). In addition, higher levels of liver enzymes and lactate dehydrogenase at admission were associated with respiratory virus coinfection in children with MP pneumonia.

CONCLUSIONS

The results of this study suggest that respiratory virus coinfection in children hospitalized with MP pneumonia may be associated with refractory MP pneumonia.

Clinical significance of Mycoplasma pneumoniae specific IgM titer in children hospitalized with Mycoplasma pneumoniae pneumonia

BACKGROUND

The present study aimed to identify the clinical significance of Mycoplasma pneumoniae (MP)-specific immunoglobulin M (IgM) titer, in addition to a diagnosis of MP infection, in children with MP pneumonia.

METHODS

This study was performed in 155 children hospitalized with MP pneumonia. The clinical features and laboratory and radiographic findings on admission in children with positive or negative MP-specific IgM titers were retrospectively reviewed from the electronic medical records.

RESULTS

The mean age of the included children was 6.0 years, and 118 (76.1%) of the children were positive for MP-specific IgM. A longer duration between symptom onset and admission (adjusted odds ratio [aOR] 1.47, 95% confidence interval [CI] 1.24-1.75), longer duration of symptoms during the illness (aOR 1.15, 95% CI 1.02-1.30), and development of extra-pulmonary manifestations (aOR 9.16, 95% CI 1.96-42.81) were significantly associated with a positive MP-specific IgM titer. Serum lactate dehydrogenase levels (aOR 1.00, 95% CI 1.00-1.01) and pneumonic infiltration involving > 50% of the total lung volume on chest radiography (aOR 4.68, 95% CI 1.12-19.55) were associated with positive MP-specific IgM in children with MP pneumonia. A poor response to stepwise treatment for MP pneumonia was more common in children with a positive MP-specific IgM titer than those with a negative MP-specific IgM titer on admission.

CONCLUSIONS

A positive MP-specific IgM titer at diagnosis of MP pneumonia may partially suggest an exaggerated immune response with a higher disease burden compared to children with MP pneumonia with a negative MP-specific IgM titer.

Pathogenic changes of community-acquired pneumonia in a children's hospital in Beijing, China before and after COVID-19 onset: a retrospective study

BACKGROUND

This study aimed to analyze the pathogenic characteristics of community-acquired pneumonia (CAP) in a children's hospital before and after the coronavirus disease 2019 (COVID-19) pandemic and to provide testimony for preventing CAP in the future.

METHODS

A retrospective analysis was performed. The information was collected from the electronic medical record system of the hospital. A total of 2739 children were included from February 1, 2019, to January 31, 2021.

RESULTS

Among these 2739 patients were 1507 (55.02%) males and 1232 (44.98%) females; the median age was 3.84 years. There were 2364 cases during the pre-COVID-19 period and 375 cases during the post-COVID-19 period. The number of hospitalized children after the pandemic was 84.14% lower. The median age after the onset was 1.5 years younger than that before the onset (4.08 years old) (Z = - 7.885, P < 0.001). After the pandemic, the proportion of CAP in school-age children and Mycoplasma pneumoniae pneumonia (MPP) and influenza virus pneumonia (IVP) decreased significantly. During the pre-COVID-19 period, the proportions of detected pathogens were as follows: MP (59.56%) > bacteria (50.42%) > viruses (29.57%) > fungi (3.43%). During the post-COVID-19 period, the pathogen proportions were bacteria (56.53%) > viruses (53.60%) > MP (23.47%) > fungi (3.73%).

CONCLUSIONS

There was a significant decrease in the number of children with CAP hospitalized after the pandemic, especially among school-age children, and the pathogen proportions of CAP with MP and IV were significantly decreased. We inferred that CAP was effectively prevented in school-age children because of the strong mitigation measures.

Early Confirmation of Mycoplasma pneumoniae Infection by Two Short-Term Serologic IgM Examination

The aim of the present study is to re-evaluate the clinical application of two-times serologic immunoglobulin M (IgM) tests using microparticle agglutination assay (MAA), an enzyme-linked immunosorbent assay (ELISA), and polymerase chain reaction (PCR) assay in diagnosing Mycoplasma pneumoniae (MP) infection. A retrospective analysis of 62 children with MP pneumonia during a recent epidemic (2019–2020) was conducted. The MAA and ELISA immunoglobulin M (IgM) and IgG measurements were conducted twice at admission and around discharge, and MP PCR once at presentation. Diagnostic rates in each test were calculated at presentation and at discharge. The seroconverters were 39% (24/62) of patients tested by MAA and 29% (18/62) by ELISA. At presentation, the diagnostic positive rates of MAA, ELISA, and PCR tests were 61%, 71%, and 52%, respectively. After the second examination, the rates were 100% in both serologic tests. There were positive correlations between the titers of MAA and the IgM values of ELISA. The single serologic IgM or PCR tests had limitations to select patients infected with MP in the early stage. The short-term, paired IgM serologic tests during hospitalization can reduce patient-selection bias in MP infection studies.

Clinical characteristics of refractory mycoplasma pneumoniae pneumonia in children treated with glucocorticoid pulse therapy

BACKGROUND

To observe the effect of corticosteroids in the treatment of children with refractory Mycoplasma pneumoniae pneumonia (RMPP) under different doses, to summarize the clinical features of children treated with glucocorticoid pulse therapy.

METHODS

The clinical data of 125 children with RMPP hospitalized in Tianjin Children's Hospital from September 2018 to October 2019 were retrospectively analyzed. They were divided into two groups according to the dose of hormone. Compare the clinical features, laboratory findings, and imaging between the two groups, and use meaningful related indicators as ROC curves to find reference indicators for pulse therapy.

RESULTS

(1) The median age of the group II was older than that of the group I(P < 0.05). (2) We found more severe presentations, higher incidence of extra-pulmonary complications and more serious radiological findings in group II, which needed oxygen more often, higher the hormone, higher usage rate of gamma globulin, higher usage rate of bronchoscopy, and higher incidence of plastic bronchitis(P < 0.05). (3) WBC, CRP, LDH, FER, D-D dimer, APTT, TT, PCT, IL-6 and the percentage of neutrophils in peripheral blood in Group II were higher than those in Group I(P < 0.05). (4) In ROC curve analysis, CRP, LDH, FER, and neutrophils of leukocyte classification were independent related factors that could be used as valuable predictors of methylprednisolone pulse therapy for RMPP in children. The cut-off values were CRP44.45 mg/L, LDH590IU/L, FER411ng/L, and neutrophils in leukocyte classification were 73.75%, respectively.

CONCLUSION

CRP ≥ 44.45 mg/L, LDH ≥ 590 IU/L, FER ≥ 411 ng/L, neutrophil≥73.75%, lung consolidation, and pleural effusion may be predictors that guide the treatment of RMPP with pulse dose of GC.

Autoimmune Hemolytic Anemia in the Pediatric Setting

Autoimmune hemolytic anemia (AIHA) is a rare disease in children, presenting with variable severity. Most commonly, warm-reactive IgG antibodies bind erythrocytes at 37 °C and induce opsonization and phagocytosis mainly by the splenic macrophages, causing warm AIHA (w-AIHA). Post-infectious cold-reactive antibodies can also lead to hemolysis following the patient’s exposure to cold temperatures, causing cold agglutinin syndrome (CAS) due to IgM autoantibodies, or paroxysmal cold hemoglobinuria (PCH) due to atypical IgG autoantibodies which bind their target RBC antigen and fix complement at 4 °C. Cold-reactive antibodies mainly induce intravascular hemolysis after complement activation. Direct antiglobulin test (DAT) is the gold standard for AIHA diagnosis; however, DAT negative results are seen in up to 11% of warm AIHA, highlighting the need to pursue further evaluation in cases with a phenotype compatible with immune-mediated hemolytic anemia despite negative DAT. Prompt supportive care, initiation of treatment with steroids for w-AIHA, and transfusion if necessary for symptomatic or fast-evolving anemia is crucial for a positive outcome. w-AIHA in children is often secondary to underlying immune dysregulation syndromes and thus, screening for such disorders is recommended at presentation, before initiating treatment with immunosuppressants, to determine prognosis and optimize long-term management potentially with novel targeted medications.

Current perspectives on atypical pneumonia in children

The major pathogens that cause atypical pneumonia are Mycoplasma pneumoniae, Chlamydophila pneumoniae, and Legionella pneumophila. Community-acquired pneumonia (CAP) caused by M. pneumoniae or C. pneumoniae is common in children and presents as a relatively mild and self-limiting disease. CAP due to L. pneumophila is very rare in children and progresses rapidly, with fatal outcomes if not treated early. M. pneumoniae, C. pneumoniae, and L. pneumophila have no cell walls; therefore, they do not respond to β-lactam antibiotics. Accordingly, macrolides, tetracyclines, and fluoroquinolones are the treatments of choice for atypical pneumonia. Macrolides are the first-line antibiotics used in children because of their low minimum inhibitory concentrations and high safety. The incidence of pneumonia caused by macrolide-resistant M. pneumoniae that harbors point mutations has been increasing since 2000, particularly in Korea, Japan, and China. The marked increase in macrolide-resistant M. pneumoniae pneumonia (MRMP) is partly attributed to the excessive use of macrolides. MRMP does not always lead to clinical nonresponsiveness to macrolides. Furthermore, severe complicated MRMP responds to corticosteroids without requiring a change in antibiotic. This implies that the hyper-inflammatory status of the host can induce clinically refractory pneumonia regardless of mutation. Empirical macrolide therapy in children with mild to moderate CAP, particularly during periods without M. pneumoniae epidemics, may not provide additional benefits over β-lactam monotherapy and can increase the risk of MRMP.

Identify clinical factors related to Mycoplasma pneumoniae pneumonia with hypoxia in children

Background

To analyze the clinical characteristics of Mycoplasma pneumoniae pneumonia with hypoxia in children, and identify the associated risk factors of hypoxia in MPP.

Methods

A retrospective case-control study was performed on 345 children with Mycoplasma pneumoniae pneumonia (MPP) admitted to our hospital wards from January 2017 to June 2019. They were divided into three groups, namely MPP with hypoxia, refractory Mycoplasma pneumoniae pneumonia (RMPP), and general Mycoplasma pneumoniae pneumonia (GMPP). The clinical features, laboratory findings, imaging, and management were collected and compared in the three groups.

Results

The MPP with hypoxia patients (n = 69) had longer disease duration, a higher extra-pulmonary complications rate, and more severe radiological abnormalities (P < 0.05). They also needed more complicated treatments (P < 0.05). Meanwhile, the levels of white blood cell count (WBC), C-reactive protein (CRP), lactic dehydrogenase (LDH), interleukin (IL)-6, ferritin, D-dimer, fibrinogen (FG), alanine aminotransferase (ALT) and the percentage of neutrophils in the MPP with hypoxia group were significantly higher than those in the RMPP group and the GMPP group (P < 0.05). In ROC curve analysis, the percentage of neutrophils, WBC, CRP, LDH, IL-6, ferritin, D-dimer, and ALT were contributed to identify the MPP with hypoxia patients. Multivariate logistic regression analysis revealed that ferritin> 174.15 ng/mL, IL-6 > 25.475 pg/ml, and pleural effusion were significantly associated with the incidence of hypoxia in MPP (P < 0.01).

Conclusion

MPP with hypoxia patients presented more serious clinical manifestations. Ferritin> 174.15 ng/mL, IL-6 > 25.475 pg/ml and pleural effusion were related risk factors for hypoxia in MPP.

Epidemiology and molecular identification of mycoplasma pneumoniae associated with respiratory infections in Zhejiang province, China, 2008-2017

Introduction

Mycoplasma pneumoniae is a common cause of respiratory infections in humans. The aim of this study was to investigate the infection of Mycoplasma pneumoniae (MP) in patients with acute respiratory tract infections in Zhejiang Province from 2008 to 2017, and to provide evidence for the early diagnosis and prevention of MP pneumonia.

Methods

MP‐DNA was detected in nasopharyngeal swabs of patients with acute respiratory tract infection by real‐time fluorescent PCR (TaqMan probe). Statistical analysis and epidemiological investigation were carried out on the test results.

Results

There were 10 296 patients with acute respiratory tract infection in Zhejiang Provincial People's Hospital from 2008 to 2017, including 4387 females and 5909 males. A total of 1251 MP‐DNA–positive patients were detected, with a total positive rate of 12.2% (1251/10296). Among 1251 patients with MP infection, 571 were female positive, with an average positive rate of 13.0% (571/4387), and 680 were male positive, with a positive rate of 11.5% (680/5909). From 2008 to 2017, the positive rates were 22.8% (33 cases), 20.9% (211 cases), 20.9% (350 cases), 5.5% (70 cases), 11.7% (136 cases), 15.2% (190 cases), 7.8% (94 cases), 5.9% (62 cases), 7.8% (56 cases), and 6.0% (49 cases), respectively. Of 1251 MP‐DNA–positive patients, 1243 (99.4%) were younger than 18 years old.

Conclusions

Mycoplasma pneumoniae infection mainly occurs from late summer to autumn and in the age below 18 years, suggesting that early diagnosis and prevention of MP infection in adolescents should be emphasized.

Immunopathogenesis of COVID-19 and early immunomodulators

The novel coronavirus disease 2019 (COVID-19) is spreading globally. Although its etiologic agent is discovered as severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), there are many unsolved issues in COVID-19 and other infectious diseases. The causes of different clinical phenotypes and incubation periods among individuals, species specificity, and cytokine storm with lymphopenia as well as the mechanism of damage to organ cells are unknown. It has been suggested that in viral pneumonia, virus itself is not a direct cause of acute lung injury; rather, aberrant immune reactions of the host to the insults from viral infection are responsible. According to its epidemiological and clinical characteristics, SARS-CoV-2 may be a virus with low virulence in nature that has adapted to the human species. Current immunological concepts have limited ability to explain such unsolved issues, and a presumed immunopathogenesis of COVID-19 is presented under the proteinhomeostasis-system hypothesis. Every disease, including COVID-19, has etiological substances controlled by the host immune system according to size and biochemical properties. Patients with severe pneumonia caused by SARS-CoV-2 show more severe hypercytokinemia with corresponding lymphocytopenia than patients with mild pneumonia; thus, early immunomodulator treatment, including corticosteroids, has been considered. However, current guidelines recommend their use only for patients with advanced pneumonia or acute respiratory distress syndrome. Since the immunopathogenesis of pneumonia may be the same for all patients regardless of age or severity and the critical immune-mediated lung injury may begin in the early stage of the disease, early immunomodulator treatment, including corticosteroids and intravenous immunoglobulin, can help reduce morbidity and possibly mortality rates of older patients with underlying conditions.

Immunochromatography for the diagnosis of Mycoplasma pneumoniae infection: A systematic review and meta-analysis

The aim of this study was to evaluate the diagnostic performance of immunochromatographic tests (ICTs) for the detection of Mycoplasma pneumoniae. Medline/Pubmed, Embase, the Cochrane Library, and ISI Web of Science were searched through June 12, 2019 for relevant studies that used ICTs for the detection of M. pneumoniae infection with polymerase chain reaction (PCR) or microbial culturing as reference standards. Pooled diagnostic accuracy with 95% confidence interval (CI) was calculated using a bivariate random effects model. We also constructed summary receiver operating characteristic curves and calculated the area under the curve (AUC). Statistical heterogeneity was evaluated by χ² test or Cochrane’s Q test. Thirteen studies including 2,235 samples were included in the meta-analysis. The pooled sensitivity and specificity for diagnosing M. pneumoniae infection were 0.70 (95% CI: 0.59–0.79) and 0.92 (95% CI: 0.87–0.95), respectively. The positive likelihood ratio (LR) was 8.94 (95% CI: 4.90–14.80), negative LR 0.33 (95% CI: 0.22–0.46), diagnostic odds ratio 29.20 (95% CI: 10.70–64.20), and AUC 0.904. In subgroup analysis, ICTs demonstrated similar pooled sensitivities and specificities in populations of children only and mixed populations (children + adults). Specimens obtained from oropharyngeal swabs exhibited a higher sensitivity and specificity than those of nasopharyngeal swab. Moreover, pooled estimates of sensitivity and accuracy for studies using PCR as a reference standard were higher than those using culture. The pooled sensitivity and specificity of Ribotest Mycoplasma^®, the commercial kit most commonly used in the included studies, were 0.66 and 0.89, respectively. Overall, ICT is a rapid user-friendly method for diagnosing M. pneumoniae infection with moderate sensitivity, high specificity, and high accuracy. This suggests that ICT may be useful in the diagnostic workup of M. pneumoniae infection; however, additional studies are needed for evaluating the potential impact of ICT in clinical practice.

The Association Between Mycoplasma pneumoniae and Chlamydia pneumoniae, a Life-Threatening Condition in Small Children-A Case Report and a Review of the Literature

Mycoplasma pneumoniae (MP) and Chlamydia pneumoniae (CP) are two atypical pathogens that may result in mild, moderate or severe acute respiratory infections. We report the case of a 2 years and 9-month-old male child admitted with prolonged fever, dry cough, and shortness of breath for which he underwent symptomatic treatment. The laboratory tests showed leukocytosis with neutrophilia, anemia, and elevated inflammatory biomarkers and the thoracic radiography revealed pleural effusion raising the suspicion of inferior right pneumonia. Although we the initial evolution was favorable being treated with 3rd class cephalosporin and Oxacillin, on the 8th day of admission the fever and the acute phase reactants levels increased as well as the quantity of the pleural effusion, requiring surgical drainage. We ruled out lung tuberculosis, but we identified positive IgM for both MP and CP. Based on these findings we changed the antibiotic therapy on Levofloxacin for 10 days with favorable evolution. MP and CP are two atypical pathogen that are difficult to be diagnosed due to their slow-growing pattern. Despite their self-limiting feature, the association between them might carry a vital risk in small children, especially in the lack of a proper and timely diagnosis.

Epidemiology and mechanism of drug resistance of Mycoplasma pneumoniae in Beijing, China: A multicenter study

Mycoplasma pneumoniae (M. pneumoniae) is one of the most common causes of community-acquired respiratory tract infections (RTIs). We aimed to investigate the prevalence of M. pneumoniae infection, antibiotic resistance and genetic diversity of M. pneumoniae isolates across multiple centers in Beijing, China. P1 protein was detected by Nested PCR to analyze the occurrence of M. pneumoniae in pediatric patients with RTI. M. pneumoniae isolates were cultured and analyzed by Nested-PCR to determine their genotypes. Broth microdilution method was used to determine the minimum inhibitory concentration (MIC) of antibiotics. Out of 822 children with RTI admitted to 11 hospitals in Beijing, 341 (41.48%) were positive for M. pneumoniae by Nested PCR and 236 (69.21%) samples had mutations in 23S rRNA domain V. The highest proportion of M. pneumoniae positive samples was observed in school-age children (118/190; 62.11%) and in pediatric patients with pneumonia (220/389; 56.56%). Out of 341 M. pneumoniae positive samples, 99 (12.04%) isolates were successfully cultured and the MIC values were determined for 65 M. pneumoniae strains. Out of these, 57 (87.69%) strains were resistant to macrolides, and all 65 strains were sensitive to tetracyclines or quinolones. M. pneumoniae P1 type I and P1 type II strains were found in 57/65 (87.69%) and 8/65 (12.31%) of cultured isolates, respectively. Overall, we demonstrated a high prevalence of M. pneumoniae infection and high macrolide resistance of M. pneumoniae strains in Beijing. School-age children were more susceptible to M. pneumoniae, particularly the children with pneumonia. Thus, establishment of a systematic surveillance program to fully understand the epidemiology of M. pneumoniae is critical for the standardized use of antibiotics in China.

Early Corticosteroid Therapy for Mycoplasma pneumoniae Pneumonia Irrespective of Used Antibiotics in Children

Antibiotics’ effect on Mycoplasma pneumoniae (MP) infection still remains controversial. A prospective study of 257 children with MP pneumonia during a recent epidemic (2015–2016) was conducted. All MP pneumonia patients were treated with corticosteroids within 24–36 h after admission. Initially, oral prednisolone (1 mg/kg) or intravenous methylprednisolone (IVMP; 1–2 mg/kg) was administered for mild pneumonia patients, and IVMP (5–10 mg/kg/day) for severe pneumonia patients. If patients showed a persistent fever for 36–48 h or disease progression, additive IVMP (5 mg/kg or 10 mg/kg) was given. Thirty-three percent of patients received only a broad-spectrum antibiotic without a macrolide. The mean age and the male-to-female ratio was 5.6 ± 3.1 years and 1:1, respectively. Seventy-four percent of patients showed immediate defervescence within 24 h, and 96% of patients showed defervescence within 72 h with improvements in clinical symptoms. Three percent of patients (8/257) who received additive IVMP also showed clinical improvement within 48 h without adverse reactions. There were no clinical or laboratory differences between patients treated with a macrolide (n = 172) and without (n = 85). Early corticosteroid therapy might reduce disease morbidity and prevent disease progression in MP pneumonia patients without side effects, and antibiotics may have limited effects on MP infection.

Epidemiological relationship between Mycoplasma pneumoniae pneumonia and recurrent wheezing episode in children: an observational study at a single hospital in Korea

OBJECTIVE

This study was aimed to evaluate epidemiological and clinical relationship between Mycoplasma pneumoniae (MP) infection and childhood recurrent wheezing episode (RWE).

DESIGN

Retrospective case note review.

SETTING

Paediatric department at a single Korean institution.

PARTICIPANTS

Consecutive admitted patients with MP pneumonia and RWE (0-15 years of age) between 2003 and 2014.

METHODS

The retrospective medical records of patients with (MP) pneumonia (n=793 for epidemiological analysis and n=501 for clinical analysis) and those with RWE (n=384) from 2003 to 2014 were analysed. Diagnosis of MP pneumonia was made based on two-times titration of IgM antibody during hospitalisation. An RWE patient was defined as one with expiratory wheezing with at least one or more wheezing episodes based on medical records.

RESULTS

During three MP pneumonia epidemics, there were no corresponding increases of patients with RWE in the epidemic years. In the 501 MP pneumonia patients, 52 (10.4%) had wheezing at presentation and 15 (3%) had RWE. The MP pneumonia patients with wheezing at presentation (n=52) were younger and were more likely to have an allergic disease history than those without wheezing (n=449). Among wheezing patients at presentation, 10 patients had previously RWE history. In a follow-up study, 13 patients (including 5 RWE) with initial wheezing and 25 patients (including 2 RWE) without wheezing had wheezy episodes after discharge. Among the total 501 patients, it was estimated that at least 31 MP pneumonia patients (6.2%) showed recurrent wheezing after initial MP infection.

CONCLUSIONS

A small part of children with MP pneumonia showed recurrent wheezing after MP pneumonia, and patients with RWE had a greater likelihood of experiencing wheezing when they had an initial MP infection. However, there were no increased admitted patients with RWE in MP pneumonia epidemic periods because of rarity of MP reinfection in children including patients with RWE or asthma.

Early Diagnosis of Mycoplasma pneumoniae in Children: Simultaneous Amplification and Testing (SAT) Is the Key

Objective: The effective diagnosis of Mycoplasma pneumoniae (MP) pneumonia (MPP) in children has been hampered by the difficulty of achieving an early diagnosis. The simultaneous amplification and testing (SAT) has the potential for early diagnosis of MP in children. Methods: Of the 1,180 children enrolled in this study, 169 were MPP antibody (Ab) seroconversion positive, 641 showed MPP positivity with a single Ab test, and 370 were MPP negative. Sera and pharyngeal swabs were collected for antibody testing and SAT detection, respectively, on admission. When the samples were Ab negative, the paired -Ab test was requested for MP 7 days later. Results: Using the Ab results as the diagnostic standard, the sensitivity, specificity, positive predictive values (PPV), and negative predictive values (NPV) for SAT were 72.8, 95.1, 97.0, and 61.5%, respectively. SAT had superior diagnostic value in the MPP group who had undergone Ab seroconversion (sensitivity: 82.2%; NPV: 92.1%) and in the short-course group also (sensitivity: 81.0%; NPV: 81.3%). Good agreement was observed between SAT and the paired-Ab results (kappa value = 0.79; P < 0.001), but there was a lack of consistency between SAT and the single-Ab test results on admission (kappa value = 0.54, P < 0.001). Conclusions: SAT is a rapid, sensitive, and specific method for MP diagnosis in pediatric patients. Our results indicate its value as an effective diagnostic tool for detecting MPP at the initial stage of an infection.

Comparison of chemiluminescence immunoassay, enzyme-linked immunosorbent assay and passive agglutination for diagnosis of Mycoplasma pneumoniae infection

Objective

This study aimed to compare the performance of chemiluminescence immunoassay (CLIA), enzyme-linked immunosorbent assay (ELISA), and passive agglutination (PA) method in detecting Mycoplasma pneumoniae (MP) infection.

Methods

This study enrolled a total of 280 patients who were consecutively seen at the Nanfang Hospital of the Southern Medical University in Guangdong Province, China, between August and December 2016. Serum was collected and examined by CLIA, ELISA, and PA, respectively.

Results

There were 180 positive (64.3%) and 100 negative cases (35.7%) by PA, 184 positive (65.7%) and 96 negative cases (34.3%) by CLIA MP-immunoglobulin (Ig) M, 89 positive (31.8%) and 191 negative cases (68.2%) by CLIA MP-IgG, 196 positive (70%) and 84 negative cases (30%) by ELISA MP-IgM, and 114 positive (40.7%) and 166 negative cases (59.3%) by ELISA MP-IgG. Patients were allocated to two groups based on PA results. In PA-negative group (≤1:40), the positive rates of MP-IgM by CLIA were 22.8% and 51.2% and by ELISA were 33.3% and 53.5%, respectively. In the PA-positive group (1:80 to ≥1:1,280), MP-IgM negative cases showed a decreasing trend: 40%, 18%, 14.3%, 10%, and 6.7% (CLIA), and 43.3%, 8%, 14.3%, 5%, and 6.7% (ELISA). The consistency between CLIA/ELISA MP-IgM, -IgG, and -IgG+MP-IgM was >92% for negative cases and >75% for positive cases, resulting in an overall consistency rate >88%. The kappa coefficients were 0.804, 0.763, and 0.806, respectively.

Conclusion

CLIA and ELISA have a higher sensitivity compared with PA. CLIA has a high concordance with ELISA. Moreover, CLIA has a higher specificity and sensitivity for the detection of IgM and IgG and should be used for the clinical diagnosis of MP infection.

Dual dye-loaded Au@Ag coupled to a lateral flow immunoassay for the accurate and sensitive detection of Mycoplasma pneumoniae infection

We present an attractive model of surface-enhanced Raman scattering-based lateral flow immunoassay (SERS-LFIA) for the sensitive and accurate detection of Mycoplasma pneumoniae (MP) infection in human serum. The SERS-LFIA strip uses Au@Ag nanoparticles (Au@Ag NPs) loaded with two layers of Raman dye 5,5′-dithiobis-(2-nitrobenzoic acid) (DTNB) as SERS tags. The advantages of the dual dye-loaded SERS tags (Au/DTNB@Ag/DTNB) are the high sensitivity and the bioconjugation flexibility of the detection antibody. As determined from our SERS-LFIA strip, human IgM was quantified by monitoring the SERS signal on the test line. The limit of detection for human IgM was 0.1 ng mL⁻¹, which was 100 times more sensitive than that by using the colorimetric method. Our assay results for 20 MP-specific IgM positive serum specimens showed 100% accuracy and detection rate, whereas the parallel enzyme-linked immunosorbent assay only showed 85% detection rate. The SERS-LFIA strip also exhibited high specificity and potential clinical applications. Therefore, our SERS-based LFIA strip has strong potential for practical applications in the sensitive and rapid detection of MP.

Schematic illustration of quantitative detection of human IgM using SERS-based lateral flow immunoassay.

Etiology of community-acquired pneumonia in 1500 hospitalized children

Childhood community‐acquired pneumonia (CAP) is a common illness; however, comprehensive studies of hospitalizations for CAP among children in China based on prospective and multicenter data collection are limited. The aim of this investigation was to determine the respiratory pathogens responsible for CAP in hospitalized children. From January to December 2015, oropharyngeal swabs and blood serum were collected from hospitalized children with CAP symptoms ranging in age from 6 months to 14 years at 10 hospitals across China. We used immunofluorescence to detect antibodies for eight respiratory viruses and passive agglutination to detect specific IgM against Mycoplasma pneumoniae (M. pneumoniae). Of 1500 children presenting with CAP, 691 (46.1%) tested positive for at least one pathogen (virus or M. pneumoniae). M. pneumoniae (32.4%) was detected most frequently, followed by respiratory syncytial virus (11.5%), adenovirus (5.0%), influenza A virus (4.1 %), influenza B virus (3.4%), parainfluenza virus types 2 and 3 type (3.1 %), parainfluenza virus type 1 (2.9%), and human metapneumovirus (0.3%). Co‐infections were identified in 128 (18.5%) of the 691 cases. These data provide a better understanding of viral etiology and M. pneumoniae in CAP in children between 6 months and 14 years in China. More study of the etiologic investigations that would further aid the management of pneumonia is required. With effective immunization for RSV, ADV, and M. pneumoniae infections, more than one‐half of the pneumonia cases in this study could have been prevented.

Role of Serum Mycoplasma pneumoniae IgA, IgM, and IgG in the Diagnosis of Mycoplasma pneumoniae-Related Pneumonia in School-Age Children and Adolescents

Mycoplasma pneumoniae is an important causative pathogen of community-acquired pneumonia in children. Rapid and reliable laboratory diagnosis of M. pneumoniae infection is important so that appropriate antibiotic treatment can be initiated to reduce the misuse of drugs and resistance rates. Anti-M. pneumoniae immunoglobulin M (IgM) is an indicator of recent primary infection but can persist for several months after initial infection. It has been suggested that anti-M. pneumoniae immunoglobulin A (IgA) can be a reliable indicator for recent M. pneumoniae infection in adults. We investigated the clinical diagnostic value of M. pneumoniae IgA in school-age children and adolescents with M. pneumoniae-related pneumonia. Eighty children with pneumonia and seropositive for M. pneumoniae IgM or with a 4-fold increase of anti-M. pneumoniae immunoglobulin G (IgG) were enrolled from May 2015 to March 2016. The titers of M. pneumoniae IgA, IgM, and IgG, the clinical features, and laboratory examinations of blood, C-reactive protein, and liver enzymes were analyzed. The initial positivity rates for M. pneumoniae IgM and IgA upon admission to the hospital were 63.6 and 33.8%, respectively. One week after admission, the cumulative positivity rates for M. pneumoniae IgM and IgA increased to 97.5 and 56.3%, respectively. Detection of M. pneumoniae IgM was more sensitive than detection of M. pneumoniae IgA for the diagnosis of M. pneumoniae-related pneumonia in school-age children and adolescents; however, paired sera are necessary for a more accurate diagnosis.