Comparison of polymerase chain reaction and the indirect particle agglutination antibody test for the diagnosis of Mycoplasma pneumoniae pneumonia in children during two outbreaks

Clinical Value of Different Test Methods in Diagnosing Mycoplasma pneumoniae Infection in Children

This research aimed to investigate the diagnostic value of passive particle agglutination test, Mycoplasma pneumoniae (MP) culture, cold agglutination test (CAT), enzyme-linked immunosorbent assay (ELISA), and polymerase chain reaction-capillary electrophoresis fragment analysis (PCR-CEFA) for MP infection. Children with respiratory tract infections suspected to be MP infection were subjected to passive particle agglutination test, MP culture, CAT, ELISA, and PCR-CEFA. A total of 146 children (81 males, 65 females, mean age: 5.74 ± 3.32 years, and mean course of disease: 9.07 ± 5.18 days) met the inclusion criteria. The positivity rate of MP detection by MP culture was 69.18% (101/146). Using the MP culture method as the standard, higher sensitivity and positive predictive value were found in the PCR-CEFA compared with the other 3 methods. Appropriate methods are selected following the advantages and disadvantages of pathogen detection, and pediatric MP infection is analyzed by integrating various test results.

Community-acquired pneumonia in children: updated perspectives on its etiology, diagnosis, and treatment

Pneumonia is a common pediatric infectious disease that is familiar to pediatricians and a major cause of hospitalization worldwide. Recent well-designed epidemiologic studies in developed countries indicated that respiratory viruses are detected in 30%-70%, atypical bacteria in 7%-17%, and pyogenic bacteria in 2%-8% of children hospitalized with community-acquired pneumonia (CAP). The etiological distribution of CAP varies widely by child age and the epidemiological season of the respiratory pathogen. Moreover, diagnostic tests, particularly for the detection of Streptococcus pneumoniae and Mycoplasma pneumoniae, the 2 major bacterial pathogens involved in pediatric CAP, have several limitations. Therefore, management and empirical antimicrobial therapy for children with CAP should be applied in a stepwise manner based on recent epidemiological, etiological, and microbiological evidence.

Diagnostic significance of HRCT imaging features in adult mycoplasma pneumonia: a retrospective study

Mycoplasma pneumoniae pneumonia (MPP) often overlaps with the clinical manifestations and chest imaging manifestations of other types of community-acquired pneumonia (CAP). We retrospectively analyzed the clinical and imaging data of a group of patients with CAP, summarized their clinical and imaging characteristics, and discussed the diagnostic significance of their certain HRCT findings. The HRCT findings of CAP researched in our study included tree-in-bud sign (TIB), ground-glass opacity (GGO), tree fog sign (TIB + GGO), bronchial wall thickening, air-bronchogram, pleural effusion and cavity. The HRCT findings of all cases were analyzed. Among the 200 cases of MPP, 174 cases showed the TIB, 193 showed the GGO, 175 showed the tree fog sign, 181 lacked air-bronchogram. In case taking the tree fog sign and lack of air-bronchogram simultaneously as an index to distinguish MPP from OCAP, the sensitivity was 87.5%, the specificity was 97.5%, the accuracy was 92.5%. This study showed that that specific HRCT findings could be used to distinguish MPP from OCAP. The combined HRCT findings including the tree fog sign and lacked air-bronchogram simultaneously would contribute to a more accurate diagnosis of MPP.

Etiology and Clinical Characteristics of Community-Acquired Pneumonia in Korean Children During the Pre-COVID-19 Period, 2015-2020

BACKGROUND

There have been many epidemiologic studies on community-acquired pneumonia (CAP) among children, most of which had substantial limitations. This study investigated the etiologic distribution and clinical characteristics of CAP in Korean children for 5 years before the coronavirus disease 2019 (COVID-19) pandemic.

METHODS

A retrospective analysis of children hospitalized for CAP at 4 referral hospitals during 2015-2020 was performed. Cases in which bronchiolitis was suspected or pulmonary infiltration was not evident on chest radiography (CXR) were excluded. Viruses and atypical bacteria were defined as detected when positive in the polymerase chain reaction test performed for respiratory specimens. Serologic testing result for Mycoplasma pneumoniae was incorporated with strict interpretation. Pyogenic bacteria were included only when cultured in blood, pleural fluid, or bronchoalveolar lavage, but those cultured in endotracheal aspirate or sputum when the case was clinically evident bacterial pneumonia were also included.

RESULTS

A total of 2,864 cases of suspected pneumonia were selected by diagnosis code and CXR findings. Medical chart and CXR review excluded nosocomial pneumonia and cases without evident infiltration, resulting in 517 (18.1%) CAP cases among 489 children. Regarding clinical symptoms, high fever was present in 59.4% and dyspnea in 19.9% of cases. Respiratory support was required for 29.2% of patients, including mechanical ventilation for 3.9%. Pathogens were detected in 49.9% of cases, with viruses in 32.3%, atypical bacteria in 17.8%, and pyogenic bacteria in 2.3% of cases. As single pathogens, M. pneumoniae (16.8%) and respiratory syncytial virus (RSV, 13.7%) were the most common. Parenteral β-lactam and macrolide antibiotics were administered in 81.6% and 50.7% of cases, respectively. A total of 12 (2.3%) cases resulted in poor outcomes, including 3 deaths.

CONCLUSION

M. pneumoniae and RSV were the most commonly detected pathogens of pediatric CAP, which was selected by strict clinical and radiologic criteria. It is necessary to carefully decide whether to use parenteral antibiotics based on the epidemiology and clinical features of CAP in children.

Metagenomic next-generation sequencing of bronchoalveolar lavage fluid assists in the diagnosis of pathogens associated with lower respiratory tract infections in children

Worldwide, lower respiratory tract infections (LRTI) are an important cause of hospitalization in children. Due to the relative limitations of traditional pathogen detection methods, new detection methods are needed. The purpose of this study was to evaluate the value of metagenomic next-generation sequencing (mNGS) of bronchoalveolar lavage fluid (BALF) samples for diagnosing children with LRTI based on the interpretation of sequencing results. A total of 211 children with LRTI admitted to the First Affiliated Hospital of Guangzhou Medical University from May 2019 to December 2020 were enrolled. The diagnostic performance of mNGS versus traditional methods for detecting pathogens was compared. The positive rate for the BALF mNGS analysis reached 95.48% (95% confidence interval [CI] 92.39% to 98.57%), which was superior to the culture method (44.07%, 95% CI 36.68% to 51.45%). For the detection of specific pathogens, mNGS showed similar diagnostic performance to PCR and antigen detection, except for Streptococcus pneumoniae, for which mNGS performed better than antigen detection. S. pneumoniae, cytomegalovirus and Candida albicans were the most common bacterial, viral and fungal pathogens. Common infections in children with LRTI were bacterial, viral and mixed bacterial-viral infections. Immunocompromised children with LRTI were highly susceptible to mixed and fungal infections. The initial diagnosis was modified based on mNGS in 29.6% (37/125) of patients. Receiver operating characteristic (ROC) curve analysis was performed to predict the relationship between inflammation indicators and the type of pathogen infection. BALF mNGS improves the sensitivity of pathogen detection and provides guidance in clinical practice for diagnosing LRTI in children.

Consideration in treatment decisions for refractory Mycoplasma pneumoniae pneumonia

Mycoplasma pneumoniae (MP) is the most common cause of childhood bacterial pneumonia. Although macrolide is known to be effective as a first-line therapy, the proportion of macrolide resistance in MP pneumonia has strikingly increased during recent 2 decades in East Asia. This is challenging to physicians since they have to decide more often whether to use secondary treatment. Diagnostic methods to detect macrolide-resistance of MP are currently not available in Korean hospitals. Even in the diagnosis of MP infection, both serologic and molecular test have limitation: inability to differentiate current illness from carriage or asymptomatic infection. Combining these 2 diagnostic methods and excluding infection caused by other respiratory pathogens allow a more reliable diagnosis. This effort is even more demanding in recent years to keep children from unnecessary exposure to secondary antibiotics. Although several observational studies have reported that tetracycline and fluoroquinolone, which are considered in the treatment of refractory MP pneumonia, have efficacy of shortening the duration of fever and respiratory symptoms, those findings need to be proven by well-designed prospective studies. The use of tetracycline and fluoroquinolone in children is generally tolerable, as supported by many observational data. However, since concerns about side effects still remain, careful consideration about benefits and risks is needed to decide their use.

Epidemiology and Clinical Features of Myocarditis/Pericarditis before the Introduction of mRNA COVID-19 Vaccine in Korean Children: a Multicenter Study

BACKGROUND

Korean health authority plans to vaccinate adolescents against coronavirus disease 2019 (COVID-19) starting high school seniors during the summer vacation of 2021. However, the myocarditis/pericarditis following COVID-19 vaccine has been reported recently in adolescents and young adults. This study was performed to answer the urgent questions about the basic epidemiology and clinical course of myocarditis/pericarditis in hospitalized patients prior to the introduction of COVID-19 vaccines in pediatric population.

METHODS

A retrospective medical record analysis including frequency, clinical characteristics, etiology and outcome of myocarditis/pericarditis was conducted in 17 years and younger patients who were hospitalized in two referral hospitals in Korea between 2010 and 2019.

RESULTS

Total 142 patients with myocarditis (n = 119) and/or pericarditis (n = 23) were identified. Median age was 5.4 years (interquartile range, 0.6-12.9 years; range, 11 days-17.8 years), and male was 61%. In adolescents aged 12-17 years, the male to female ratio was 3.2. Myocarditis/pericarditis occurred 0.70 per 1,000 in-patients during the study period: 0.96 (< 1 year), 0.50 (1-5 years), 0.67 (6-11 years) and 1.22 (12-17 years) per 1,000 in-patients, respectively. There was an increasing tendency for the annual frequency from 0.34 in 2010 to 1.25 per 1,000 in-patients in 2019 (P = 0.021). Among the 56 (40%) proven pathogens at admission, Mycoplasma pneumoniae (n = 11, 8%) and enterovirus (n = 10, 7%) were most common. Of the 142 patients, 99 (70%) required pediatric intensive care unit care and 10 (7%) received heart transplantation. In addition, 61 patients (61/131, 47%) without heart medication at admission needed heart medication when they were discharged. Eleven (7.7%) patients died, of which five patients were previously healthy. The median age of deceased patients was lower than the survival group (0.8 vs. 6.3 years, P = 0.014).

CONCLUSION

The frequency of myocarditis/pericarditis was highest among male adolescent in-patients; however, the outcome was favorable in this group without any mortality.

Macrolide resistance and molecular typing of Mycoplasma pneumoniae infections during a 4 year period in Spain

Background

Mycoplasma pneumoniae (MP) causes community-acquired pneumonia affecting mainly children, and tends to produce cyclic outbreaks. The widespread use of macrolides is increasing resistance rates to these antibiotics. Molecular tools can help in diagnosis, typing and resistance detection, leading to better patient management.

Objectives

To assess the MP genotypes and resistance pattern circulating in our area while comparing serological and molecular diagnosis of MP.

Methods

Molecular and serological diagnosis of MP was performed in 821 samples collected in Badalona (Barcelona, Spain) from 2013 to 2017. Multiple locus variable number tandem repeat analysis (MLVA) and macrolide resistance detection by pyrosequencing were performed in those cases positive by PCR. Presence of respiratory viruses and relevant clinical data were also recorded.

Results

MP was detected in 16.8% of cases by PCR, with an overall agreement with serology of 76%. Eleven different MLVA types were identified, with 4-5-7-2 (50.1%) and 3-5-6-2 (29.2%) being the most abundant, with the latter showing a seasonal increase during the study. A total of 8% of the strains harboured a point substitution associated with macrolide resistance, corresponding mainly to an A2063G 23S rRNA mutation and directly related to previous macrolide therapy. Analysis of respiratory viruses showed viral coinfections in most cases.

Conclusions

Serological and molecular tools combined could improve MP diagnosis and the analysis of its infection patterns. Macrolide resistance is associated with previous therapy. Given that MP pneumonia usually resolves spontaneously, it should be reconsidered whether antibiotic treatment is suitable for all cases.

Clinical Efficacy of Doxycycline for Treatment of Macrolide-Resistant Mycoplasma pneumoniae Pneumonia in Children

In areas with high prevalence of macrolide-resistant Mycoplasma pneumoniae (MRMP) pneumonia, treatment in children has become challenging. This study aimed to analyze the efficacy of macrolides and doxycycline with regard to the presence of macrolide resistance. We analyzed children with MP pneumonia during the two recent epidemics of 2014–2015 and 2019–2020 from four hospitals in Korea. Nasopharyngeal samples were obtained from children with pneumonia for MP cultures and polymerase chain reaction (PCR). Macrolide resistance was determined by the analysis of 23S rRNA gene transition. Time to defervescence and to chest X-ray improvement were analyzed. Of 145 cases, the median age was 5.0 years and MRMP accounted for 59 (40.7%). Among macrolide-susceptible MP (MSMP), 78 (90.7%) were treated with macrolides and 21 (35.6%) in the MRMP group with doxycycline. In MRMP pneumonia, shorter days to defervescence (2 vs. 5 days, p < 0.001) and to chest X-ray improvement (3 vs. 6 days, p < 0.001) in the doxycycline group than in the macrolide group was observed, whereas no differences were observed among children with MSMP pneumonia. Compared to macrolides, treatment with doxycycline resulted in better outcomes with a shorter time to defervescence and to chest X-ray improvement among children with MRMP pneumonia.

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.

Ability of high-resolution computed tomography to distinguish Mycoplasma pneumoniae pneumonia from other bacterial pneumonia: Significance of lateral bronchial lesions, less air bronchogram, and no peripheral predominance

BACKGROUND

No study has investigated the capability of high-resolution computed tomography (HRCT) to detect a lateral bronchus abnormality, degree of air bronchogram, and distribution of affected lesions in the diagnosis of Mycoplasma pneumoniae pneumonia (MPP).

METHODS

We prospectively enrolled patients with serologically-confirmed MPP or culture-confirmed other bacterial pneumonia (OBP). The distribution of affected areas, abnormalities in lateral bronchial lesions, the degree of air bronchogram, and previously reported findings on HRCT were evaluated for MPP and OBP. Predictive HRCT findings for MPP were determined by logistic regression analysis. We provisionally designed our HRCT criteria (negative, probable, or highly suspected) for diagnosing MPP and investigated the diagnostic yield of the HRCT criteria.

RESULTS

Sixty-three MPP and 126 OBP patients were included in this study. Logistic regression analysis showed that the absence of peripheral predominance, bronchial wall thickening, lateral bronchial wall thickening, intralobular or lobular ground-glass opacities, intralobular ground-glass opacities connected to a lateral bronchus, and less air bronchogram in infiltrates were significant predictors of MPP. Our HRCT criteria showed that the sensitivity and specificity in negative, probable, and highly suspected MPP were 0.0 and 0.33, 1.0 and 0.69, and 0.5 and 0.98, respectively.

CONCLUSIONS

HRCT had considerable ability to detect a lateral bronchial abnormality and to diagnose or rule out MPP based on the distribution of affected areas, abnormalities in lateral bronchial lesions, and the degree of air bronchogram in the infiltrates.

Correlation between chest radiographic findings and clinical features in hospitalized children with Mycoplasma pneumoniae pneumonia

Background

Radiologic evaluation of children with Mycoplasma pneumoniae is important for diagnosis and management.

Objective

To investigate the correlation between chest radiographic findings and the clinical features in children with Mycoplasma pneumoniae pneumonia.

Materials and methods

This study included 393 hospitalized children diagnosed with M. pneumoniae pneumonia between January 2000 and August 2016. Their clinical features and chest radiographs were reviewed. Radiographic findings were categorized and grouped as consolidation group (lobar or segmental consolidation) and non-consolidation group (patchy infiltration, localized reticulonodular infiltration, or parahilar peribronchial infiltration).

Results

Lobar or segmental consolidation (37%) was the most common finding, followed by parahilar or peribronchial infiltration (27%), localized reticulonodular infiltration (21%) and patchy infiltration (15%). The consolidation group was more frequently accompanied by pleural effusions (63%), compared to the non-consolidation group (16%). Compared with patients in the non-consolidation group, those in the consolidation group were associated with a significantly higher rate of hypoxia, tachypnea, tachycardia, extrapulmonary manifestations, prolonged fever, and longer periods of anti-mycoplasma therapy and hospitalization. Lobar or segmental consolidation was significantly more frequent in children ≥5 years old (44%) compared with children 2–5 years old (34%) and <2 years old (13%). Parahilar peribronchial infiltration was significantly more frequent in children <2 years old (56%) compared with children 2–5 years old (32%) and ≥5 years old (18%).

Conclusion

The chest radiographic findings of children with M. pneumoniae pneumonia correlate well with the clinical features. Consolidative lesions were frequently observed in older children and were associated with more severe clinical features.

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.

Contribution of Co-detected Respiratory Viruses and Patient Age to the Clinical Manifestations of Mycoplasma Pneumoniae Pneumonia in Children

BACKGROUND

The clinical spectrum of Mycoplasma pneumoniae pneumonia is widely variable. This study evaluated the clinical manifestations of M. pneumoniae pneumonia in children of different age groups and by the presence of co-detected respiratory virus.

METHODS

This study included children hospitalized with M. pneumoniae pneumonia between 2010 and 2015. At the time of pneumonia diagnosis, a nasopharyngeal aspirate was analyzed for respiratory viruses by reverse transcription-polymerase chain reaction (RT-PCR). The clinical manifestations and laboratory findings were reviewed from medical records.

RESULTS

Of the 286 children with M. pneumoniae pneumonia, 84 (29.4%) had a co-detected respiratory virus, with the highest co-detection rate in young children (51.9% of children <2 years; P = 0.002). In children <2 years, with and without co-detected virus, wheezing occurred in 35.7% and 15.4%, respectively. Among the 202 children without any virus detected, only 6.4% were <2 years. These young children showed fewer median days of fever than the children ≥2 years (8 vs. 11 days; P = 0.022). Children ≥2 years tended to have accompanying skin rashes (21.7% vs.7.7%; P = 0.310) and elevated liver enzymes (21.7% vs. 0%; P = 0.075) more frequently than children <2 years. Only 53.8% of the patients <2 years were treated with macrolide compared with 94.1% of the patients ≥2 years (P < 0.001).

CONCLUSIONS

The clinical manifestations of M. pneumoniae pneumonia in young children are milder than those in older children. A high prevalence of co-detected respiratory virus in young children suggests that virus might play a role in making pneumonia clinically apparent in this age group.

A comparison study between GeXP-based multiplex-PCR and serology assay for Mycoplasma pneumoniae detection in children with community acquired pneumonia

Background

Diagnosis of community-acquired pneumonia (CAP) caused by Mycoplasma pneumoniae (Mp) in children has been hampered by difficulty in obtaining convalescent serum and time constraints. In this study, the two diagnostic assays that targeted respectively on Mp-antibody and Mp-DNA were retrospectively investigated.

Methods

A total of 3146 children were clinically diagnosed to have CAP and were confirmed by chest X-ray during March 2015 to February 2016 in Children’s hospital of Hebei Province (China). Both of the sera and sputum samples were collected in 24 h after their admission. The Mp-antibody was examined by the passive particle agglutination assay and a fourfold or greater increase of antibody titers of paired sera or≧1:160 titer of single serum was set as the serology positive. Mp-DNA in the sputum samples was tested by a multiplex-PCR method named GeXP assay (multiplex PCR combined with automated capillary electrophoresis). In order to eliminate the false positive results caused by the asymptomatic carriage after infected by M. pneumoniae, the inconsistent samples were tested by the real-time isothermal transcription-mediated RNA amplification assay (SAT).

Results

The inter-rated agreement test was performed in 3146 CAP patients, with a highest kappa value in the school-age children as 0.783. There were 6.29% (198/3146) cases showed inconsistent results determined by GeXP and serology assay. All of the 19 GeXP(+)/Serology (−) samples and a randomly chosen 27 from 179 GeXP(−)/Serology (+) samples were tested by SAT assay, and a 97.8% diagnosis agreement was observed between SAT and GeXP assay, but not with the serology assay. In addition, patients who were detected only by serology or only by multiplex-PCR were significantly younger than those with both methods positive (3.0 and 1.5 years vs. 5.0 years, p < 0.01). The Viral-Mp coinfection accounted for 37.0% (97/262), which was more common in winter and spring (p < 0.05) and in the infantile group (p < 0.01), compared to the pure Mp positive ones.

Conclusion

In some children CAP cases, the Mp laboratory diagnosis was inconsistent between serology and multiplex-PCR assay. Verified by the SAT assay, the GeXP showed a more sensitive and reliable performance compared with the serology assay. Furthermore, employing the multiplex-PCR could provide more information on the associated pathogens for clinical assessment of CAP.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-017-2614-3) contains supplementary material, which is available to authorized users.

Radiologic findings as a determinant and no effect of macrolide resistance on clinical course of Mycoplasma pneumoniae pneumonia

Background

With the emergence of macrolide resistance, concerns about the efficacy of macrolides for the treatment of Mycoplasma pneumoniae (MP) pneumonia in children have been raised. This study aimed to determine the effect of macrolide resistance on the outcome of children who were hospitalized with MP pneumonia.

Methods

Between 2010 and 2015, we performed culture of MP from nasopharyngeal samples obtained from children who were hospitalized with pneumonia at five hospitals in Korea. Macrolide resistance was determined by the analysis of 23S rRNA gene transition and the minimal inhibitory concentrations of four macrolides. Medical records were reviewed to analyze the clinical response to treatment with macrolides.

Results

MP was detected in 116 (4.8%) of the 2436 children with pneumonia. MP pneumonia was prevalent in 2011 and 2015. Of the 116 patients with MP pneumonia, 82 (70.7%) were macrolide-resistant. There were no differences in the age distribution, total duration of fever, and chest x-ray patterns between the macrolide-susceptible and macrolide-resistant groups. After macrolide initiation, mean days to defervescence were longer in the macrolide-resistant group than in macrolide-susceptible group (5.7 days vs. 4.1 days, P = 0.021). However, logistic regression analysis revealed that the presence of extrapulmonary signs (P = 0.039), homogeneous lobar consolidation (P = 0.004), or parapneumonic effusion (P < 0.001) were associated with fever duration of ≥7 days after the initiation of macrolides, regardless of macrolide resistance.

Conclusions

This study demonstrated that fever duration in MP pneumonia was determined by the radiologic findings of chest x-ray, not by the presence of macrolide resistance. The results highlight the need for future studies to assess therapeutic benefit from macrolides in the treatment of children with MP pneumonia.

The epidemiology and clinical features of Mycoplasma pneumoniae infection in neonates

OBJECTIVES

This retrospective study was aimed to explore the epidemiological and clinical profiles of Mycoplasma pneumoniae infection in neonates.

METHODS

From 2011 to 2014, 1322 hospitalized neonates with lower respiratory tract infections were screened for Mycoplasma pneumoniae by detection of Mycoplasma pneumoniae antibodies using Serion ELISA classic Mycoplasma pneumoniae kits.

RESULTS

Mycoplasma pneumoniae was identified in 89 (6.7%) patients. The age ranged from 1 day to 28 days with a median of 22 days. The male to female ratio was 1.15:1. Mycoplasma pneumoniae infection peaked in spring (from March through May) and winter (from December through February). Compared with non-Mycoplasma pneumoniae infected neonates, those with Mycoplasma pneumoniae infection were older, presented fever more frequently, and had less tachypnea.

CONCLUSIONS

Mycoplasma pneumoniae could be an important etiologic agent for respiratory tract infection in neonates. In neonates Mycoplasma pneumoniae infection was usually associated with older age, presence of fever, and less tachypnea. Mycoplasma pneumoniae infection in neonates tends to be a mild process.

Comparisons of etiology and diagnostic tools of lower respiratory tract infections in hospitalized young children in Southern Taiwan in two seasons

BACKGROUND

Lower respiratory tract infections (LRTIs) play an important role in pediatric diseases; however, there are limited data about LRTIs in Southern Taiwan. This study aimed to investigate the clinical and epidemiological data of LRTIs in this area.

METHODS

Children aged under 5 years who were hospitalized at a medical center in Southern Taiwan with acute LRTIs from July 2010 to October 2010 (summer) and from March 2011 to May 2011 (spring) were prospectively enrolled. Nasopharyngeal aspirates were obtained and sent for viral cultures, multiplex polymerase chain reaction (PCR), and traditional quick tests. The clinical features, laboratory data, and imaging findings were recorded and analyzed.

RESULTS

A total of 90 children were enrolled, 70 of whom had detectable pathogens. The positive rate of conventional viral and bacterial cultures was 25.6%, which increased to 77.77% after combining with the two multiplex PCR methods. Adenovirus and enterovirus were the most common viral etiologies identified (26.5% of cases) and Streptococcus pneumoniae was the leading bacterial etiology (46.4%). The seasonal trend of viral infections in Southern Taiwan was different from Northern Taiwan. There were no differences in demographic data, severity of disease, or hospital stay between single and mixed infections. A similar result was found between nonpneumococcal and pneumococcal infections.

CONCLUSION

Viral infections were the main etiologies of LRTIs in young children. Multiplex PCR methods are rapid assays that can increase the diagnostic yield rate. Mixed infections do not seem to affect the severity of disease. Early detection may aid clinicians in appropriate decision-making and treatment.

Novel aspects on the pathogenesis of Mycoplasma pneumoniae pneumonia and therapeutic implications

Mycoplasma pneumoniae (Mp) is a leading cause of community acquired pneumonia. Knowledge regarding Mp pneumonia obtained from animal models or human subjects has been discussed in many different reports. Accumulated expertise concerning this critical issue has been hard to apply clinically, and potential problems may remain undiscovered. Therefore, our multidisciplinary team extensively reviewed the literature regarding Mp pneumonia, and compared findings from animal models with those from human subjects. In human beings, the characteristic pathological features of Mp pneumonia have been reported as alveolar infiltration with neutrophils and lymphocytes and lymphocyte/plasma cell infiltrates in the peri-bronchovascular area. Herein, we demonstrated the novel aspects of Mp pneumonia that the severity of the Mp pneumonia seemed to depend on the host innate immunity to the Mp, which might be accelerated by antecedent Mp exposure (re-exposure or latent respiratory infection) through up-regulation of Toll-like receptor 2 expression on bronchial epithelial cells and alveolar macrophages. The macrolides therapy might be beneficial for the patients with macrolide-resistant Mp pneumonia via not bacteriological but immunomodulative effects. This exhaustive review focuses on pathogenesis and extends to some therapeutic implications such as clarithromycin, and discusses the various diverse aspects of Mp pneumonia. It is our hope that this might lead to new insights into this common respiratory disease.

Clinical significance of different bacterial load of Mycoplasma pneumoniae in patients with Mycoplasma pneumoniae pneumonia

Objective

This retrospective study was conducted to investigate the clinical significance of different Mycoplasma pneumoniae bacterial load in patients with M. pneumoniae pneumonia (MP) in children.

Methods

Patients with MP (n = 511) were identified at the Children's Hospital Affiliated to Soochow University database during an outbreak of MP between January 2012 and February 2013.

Results

Comparing patients with high and low bacterial load those with higher loads were significantly older (p < 0.01) and had fever significantly more frequently (p = 0.01). Presence of wheezing at presentation was associated with low bacterial load (p = 0.03). Baseline positive IgM was present in 93 (56.4%) patients with high bacterial load compared to 46 (27.8%) patients with low bacterial load (p < 0.001). Co-infection with viruses was found significantly more frequent among patients with low bacterial load (24.2%) than those with high bacterial load (8.5%) [p < 0.001]. Bacterial co-infection was also more frequently detected among patients with low bacterial load (22.4%) than in those with high bacterial load (12.1%) [p = 0.01].

Conclusion

M. pneumoniae at a high bacterial load could be an etiologic agent of respiratory tract disease, whereas the etiologic role of MP at a low bacterial load remains to be determined.

Prognostic values of a combination of intervals between respiratory illness and onset of neurological symptoms and elevated serum IgM titers in Mycoplasma pneumoniae encephalopathy

BACKGROUND/PURPOSE

To retrospectively analyze the clinical manifestations of Mycoplasma pneumoniae (M. pneumoniae)-associated encephalopathy in pediatric patients.

METHODS

Pediatric patients with positive serum anti-M. pneumoniae immunoglobulin M (IgM) were enrolled in this study. Clinical signs and symptoms, laboratory data, neuroimaging findings, and electrophysiological data were reviewed.

RESULTS

Of 1000 patients identified, 11 (1.1%; male:female ratio = 7:4) had encephalopathy and were admitted to the pediatric intensive care unit. Clinical presentation included fever, symptoms of respiratory illness, and gastrointestinal upset. Neurological symptoms included altered consciousness, seizures, coma, focal neurological signs, and personality change. Neuroimaging and electroencephalographic findings were non-specific. Specimens of cerebrospinal fluid (CSF) for M. pneumoniae polymerase chain reaction (PCR) were negative. Higher M. pneumoniae IgM titers and longer intervals between respiratory and CNS manifestations were associated with worse outcomes.

CONCLUSION

Clinical manifestations of M. pneumoniae-associated encephalopathy were variable. Diagnosis of M. pneumoniae encephalopathy should not rely on CSF detection of M. pneumoniae by PCR. M. pneumoniae IgM titers and intervals between respiratory and CNS manifestations might be possibly related to the prognosis of patients with M. pneumoniae-associated encephalopathy.

Epidemiology and associations with climatic conditions of Mycoplasma pneumoniae and Chlamydophila pneumoniae infections among Chinese children hospitalized with acute respiratory infections

Background

The incidence of severe acute respiratory tract infections in children caused by Mycoplasma pneumoniae (syn. Schizoplasma pneumoniae) and Chlamydophila pneumoniae (formerly Chlamydia pneumoniae) varies greatly from year to year and place to place around the world. This study investigated the epidemiology of M. pneumoniae and C. pneumoniae infections among children hospitalized with acute respiratory infections in Suzhou, China in the year 2006, and associations between incidence rates and climatic conditions.

Methods

Nasopharyngeal aspirates obtained from 1598 patients (aged 26.4 ± 28.3 months; range, 1 month to 13 years) were analyzed with real-time PCR and ELISA. Meteorological data were obtained from the weather bureau.

Results

About 18.5% of patients were infected with M. pneumoniae and, C. pneumoniae, or both. Isolated M. pneumoniae infection was positively correlated with increasing age (χ² = 34.76, P < 0.0001). Incidence of M. pneumoniae infection was seasonal with a peak in summer (P < 0.0001) and minimum in winter (P = 0.0001), whereas C. pneumoniae infection was low only in autumn (P = 0.02). Monthly mean temperature was strongly correlated with the incidence of M. pneumoniae infection (r = 0.825, P = 0.001).

Conclusions

M. pneumoniae and C. pneumoniae are important infectious agents in hospitalized children with acute respiratory tract infections. M. pneumoniae infection showed a strong direct correlation with environmental temperature.

[Two uncommon extrapulmonary forms of Mycoplasma pneumoniae infection]

Mycoplasma pneumonia is the second most frequent bacterium in pneumonia and the leading intracellular type. M. pneumoniae pulmonary infection is characterized by a slower onset profile and a lower biological inflammatory picture than pneumococcal infection. Both upper and lower respiratory tracts are often affected and sometimes a Kawasaki-like syndrome can be associated, with conjunctivitis or cheilitis. Extrapulmonary forms of the disease can occur, whether or not it is associated with pulmonary infection. We report two cases: in the first case, a renal form of M. pneumoniae disease developed in a 6-year-old girl, with membranous proliferative glomerulonephritis expressed as a picture of impure nephritic syndrome with decreased serum complement concentration, following an upper respiratory infection. Diagnosis was obtained by means of a kidney biopsy. The second case occurred in an 8-year-old girl who expressed, after a respiratory tract infection, neurological symptoms such as ocular flutter, perception disorder, and ataxia. This onset is typical of post-infectious rhombencephalitis. Biological investigations and imaging were normal. In both cases, M. pneumoniae infection was diagnosed on the basis of immunoglobulin M-positive serology. Direct exploration of the bacterium was negative, due to its fragility and delayed diagnostic hypothesis. Several forms of M. pneumoniae infection are either the direct effect of the bacterium or are secondary to a cross-immunological reaction. As its frequency is increasing, M. pneumoniae infection should be raised as a cause of atypical, less well-known extrapulmonary forms of the disease.

Evaluation of P1 adhesin epitopes for the serodiagnosis of Mycoplasma pneumoniae infections

Most glycolipid antigens used for serological tests of Mycoplasma pneumoniae are not M. pneumonia‐specific, and can cross‐react with other microorganism antigens and body tissues, resulting in false positives. It is important to identify M. pneumonia‐specific antigen(s) for serological testing and correct diagnosis. Two epitopes, rP1‐534 and rP1‐513, of P1 adhesin predicted by bioinformatics were successfully expressed and purified, and could be recognized by serum samples from M. pneumoniae‐infected patients and His tag antibodies by Western blot. There was no cross‐reactivity between the anti‐recombinant proteins serum and other respiratory antigens. A total of 400 patients were investigated, their respiratory specimens tested by PCR, and sera tested by a commercial test kit; 56 with positive sera and positive respiratory specimens were designated as standard positive serum and 63 patients were designated as standard negative serum. The purified recombinant proteins were used as a combination of antigens or separately to test the serum. Serological test demonstrated that rP1‐513 of the C terminal of P1 adhesin is a new candidate antigen with greater sensitivity and specificity for IgG and IgM serodiagnosis of M. pneumoniae‐infected patients. The results confirmed that rP1‐513 could be a useful new antigen for the immunodiagnosis of M. pneumoniae infection.

A case of acute myopericarditis associated with Mycoplasma pneumoniae infection in a child

Mycoplasma pneumoniae (M. pneumoniae) primarily causes respiratory tract infections in persons aged 5-20 years. Tracheobronchitis and bronchopneumonia are the most commonly recognized clinical symptoms associated with M. pneumoniae infection. Complications of this infection are unusual; in particular, cardiac involvement is very rare and is generally accompanied by pneumonia. Nonrespiratory illness can therefore involve direct invasion by M. pneumoniae or autoimmune mechanisms, as suggested by the frequency of cross reaction between human antigens and M. pneumoniae. Herein, we report a case of severe acute myopericarditis with pneumonia caused by M. pneumoniae in a healthy young child who presented with fever, lethargy, oliguria and dyspnea. She survived with aggressive therapy including clarithromycin, intravenous immunoglobulin, inotropics, and diuretics. The patient was discharged on the 19th day after admission and followed up 1 month thereafter at the outpatient clinic without sequelae.

Investigation of Mycoplasma pneumoniae infection in pediatric population from 12,025 cases with respiratory infection

Although Mycoplasma pneumoniae (MP) is a major pathogen of primary atypical pneumonia in children, the clinical and laboratory characteristics of MP infection in large pediatric population are less reported. Here, we retrospectively analyzed 12,025 hospitalized children with respiratory infection by using serology and polymerase chain reaction (PCR) methods simultaneously. The results showed that 2433 (20.23%) children had MP infection, which mainly occurred in November to April. The presence of sore throat and pharyngitis was peculiar to MP infection. The positive percentage of MP-DNA was higher than that of MP-IgM in children aged <1 (P < 0.0001) and 1-3 years (P < 0.0001). Moreover, the positive rate of P1 gene, the key adhesion gene for MP infection, was higher in children with MP infection than in those with other pathogens (P < 0.0001). Our work provides the clinical information of children MP infection and highlights the superiority of PCR and potential usage of P1 as a diagnosis target for MP infection.

Quantitative PCR for Etiologic Diagnosis of Methicillin-Resistant Staphylococcus aureus Pneumonia in Intensive Care Unit

Background

Ventilator-associated pneumonia (VAP) requires prompt and appropriate treatment. Since methicillin-resistant Staphylococcus aureus (MRSA) is a frequent pathogen in VAP, rapid identification of it, is pivotal. Our aim was to evaluate the utility of quantitative polymerase chain reaction (qPCR) as a useful method for etiologic diagnoses of MRSA pneumonia.

Methods

We performed qPCR for mecA, S. aureus-specific femA-SA, and S. epidermidis-specific femA-SE genes from bronchoalveolar lavage or bronchial washing samples obtained from clinically-suspected VAP. Molecular identification of MRSA was based on the presence of the mecA and femA-SA gene, with the absence of the femA-SE gene. To compensate for the experimental and clinical conditions, we spiked an internal control in the course of DNA extraction. We estimated number of colony-forming units per mL (CFU/mL) of MRSA samples through a standard curve of a serially-diluted reference MRSA strain. We compared the threshold cycle (Ct) value with the microbiologic results of MRSA.

Results

We obtained the mecA gene standard curve, which showed the detection limit of the mecA gene to be 100 fg, which corresponds to a copy number of 30. We chose cut-off Ct values of 27.94 (equivalent to 1×10⁴ CFU/mL) and 21.78 (equivalent to 1×10⁵ CFU/mL). The sensitivity and specificity of our assay were 88.9% and 88.9% respectively, when compared with quantitative cultures.

Conclusion

Our results were valuable for diagnosing and identifying pathogens involved in VAP. We believe our modified qPCR is an appropriate tool for the rapid diagnosis of clinical pathogens regarding patients in the intensive care unit.

Diagnosis of pneumococcal empyema using immunochromatographic test on pleural fluid and serotype distribution in Korean children

To evaluate the diagnostic value of immunochromatographic test (ICT) on pleural fluid in diagnosing pneumococcal empyema in children and to determine pneumococcal serotypes, 62 exudative parapneumonic effusions from Korean children were tested with culture, ICT for S. pneumoniae, pneumococcal autolysin polymerase chain reaction (PCR), and subsequent sequencing. Of the 62 patients, culture was positive in 3 patients only (4.8%). Pneumococci were identified in 13 samples (21.0%) by sequencing-confirmed PCR and ICT, respectively. When pneumococcal empyema was defined by either positive culture or sequence confirmation, the sensitivity of ICT was 76.9% (10/13) and the specificity of ICT was 93.9%. Eight of 10 patients with positive ICT and culture-negative results had a history of prior antibiotics use, whereas none of the culture-proven cases had. Serotypes of PCR-positive samples were determined by multiplex PCR assays. Multiplex PCR detected serotypes 19A (6), 1 (1), 14 (1), 34 (1), and untypable (4). ICT on pleural fluid is a relatively sensitive and highly specific method for diagnosis of pneumococcal empyema, especially in children given prior antibiotics.

Detection of Mycoplasma pneumoniae in different respiratory specimens

Mycoplasma pneumoniae (M. pneumoniae) is an important community-acquired pneumonia pathogen. Serological test and polymerase chain reaction (PCR) assay are the two main laboratory tests to detect M. pneumoniae now. Little information was compared about the sensitivity and specificity of PCR using different specimens including bronchoalveolar lavage (BAL) and nasopharyngeal aspirate (NPA). The aim of the present study was to evaluate diagnostic values of different specimens by fluorescence quantitative real-time PCR and to find clinical features helpful to diagnose M. pneumoniae pneumonia (MPP). Four hundred and six hospitalized pneumonia children were studied. M. pneumoniae DNA in NPA and BAL samples were detected by fluorescence quantitative real-time PCR. M. pneumoniae-specific IgM was tested by ELISA. MPP were diagnosed based on positive M. pneumoniae-specific IgM in 101 (24.9%) children. The median ages of MPP and non-MPP children were 4.1 and 2.4 years, respectively, with significant difference between them (p < 0.001). Laboratory results including leukocyte count, neutrophil percentage, immunoglobulins, except serum IgM, subgroups of T lymphocyte, and BAL cell count had no significant differences in MPP and non-MPP. BAL macrophage cell percentage was lower in BAL-PCR positive children (p = 0.003), while BAL neutrophil percentage was higher in BAL-PCR positive children (p = 0.007). PCR from NPA and BAL were similar in diagnostic parameters, including sensitivity, specificity, PPV, and NPV (78.6%, 63.4%, 39.8%, and 90.6% for NPA-PCR, respectively; 70.3%, 58.7%, 36.0%, and 85.6% for BAL-PCR, respectively).

CONCLUSIONS

NPA is better than BAL as PCR sample in MPP diagnosis for similar performance in PCR assay, cheap, and less invasive. BAL is useful in defining local inflammatory condition. Age is the only prefigurative factor in MPP.

Emerging advances in rapid diagnostics of respiratory infections

Recent developments in rapid diagnostics for respiratory infections have mostly occurred in the areas of antigen and nucleic acid detection. Nucleic acid amplification tests have improved the ability to identify respiratory viruses in clinical specimens and have played pivotal roles in the rapid characterization of new viral pathogens. Antigen-detection assays in immunochromatographic or similar formats are most easily developed as near-patient tests, although they have been developed commercially only for a limited range of respiratory pathogens. New approaches for respiratory pathogen detection are needed, and breath analysis is an exciting area with enormous potential.

Polymerase chain reaction is superior to serology for the diagnosis of acute Mycoplasma pneumoniae infection and reveals a high rate of persistent infection

Background

Diagnosis of Mycoplasma pneumoniae (MP) infection is traditionally based on serology, which may require more than two weeks for diagnostic antibodies to develop. PCR-based methods offer earlier diagnosis. During a community outbreak of MP infection, we compared semi-nested and real-time PCR of oropharyngeal swabs with serology for diagnosis of MP infection at different time points after disease onset. PCR-positive individuals were followed longitudinally to assess the persistence of MP DNA in throat secretions. We also studied carriage of MP among household contacts and school children.

Results

MP infection was diagnosed in 48 of 164 patients with respiratory tract infection. Forty-five (29%) had detectable MP DNA in oropharynx. A significant increase in MP IgG IgG titre or MP IgM antibodies was detected in 44/154 (27%) subjects. Two MP PCR-positive patients lacked antibody responses. Sera were missing from another two patients. The agreement between serology and PCR was good, κ = 0.90.

During the first three weeks after disease onset the performance of PCR was excellent and all patients but one were detected. In contrast, only 21% of the patients with confirmed MP infection were positive by serum 1 during the first symptomatic week (56% during the second and 100% during the third week). Only 1/237 (0.4%) school children was positive by PCR. This child had respiratory symptoms. Eighteen of 22 (75%) symptomatic household contacts were MP PCR positive.

Persistence of MP DNA in the throat was common. Median time for carriage of MP DNA was 7 weeks after disease onset (range 2 days – 7 months). Adequate antibiotic treatment did not shorten the period of persistence. Bacterial load, measured by quantitative real-time PCR declined gradually, and all followed patients eventually became PCR-negative.

Conclusion

PCR is superior to serology for diagnosis of MP infection during the early phases of infection. Persistent, sometimes long-term, carriage of MP DNA in the throat is common following acute infection, and is not affected by antibiotic therapy. Asymptomatic carriage of MP even during an outbreak is uncommon.