Diagnosis of Mycoplasma pneumoniae Pneumonia with Measurement of Specific Antibody-Secreting Cells

New Insights into the Epidemiological Characteristics of Mycoplasma pneumoniae Infection before and after the COVID-19 Pandemic

Mycoplasma pneumoniae (M. pneumoniae), a prevalent respiratory pathogen affecting children and adolescents, is known to trigger periodic global epidemics. The most recent significant outbreak commenced in the first half of 2023 and reached its peak globally during the autumn and winter months. Considering the worldwide repercussions of the COVID-19 pandemic, it has become increasingly essential to delve into the epidemiological characteristics of M. pneumoniae both before and after the pandemic. This review aims to provide a comprehensive analysis of the key features of M. pneumoniae epidemics in the pre-and post-COVID-19 contexts, including but not limited to shifts in the susceptible population, the molecular genotypes of the pathogen, the clinical manifestations, and potential new trends in drug resistance. Additionally, we will introduce the latest advancements in the diagnosis of M. pneumoniae.

A randomized controlled non-inferiority trial of placebo versus macrolide antibiotics for Mycoplasma pneumoniae infection in children with community-acquired pneumonia: trial protocol for the MYTHIC Study

BACKGROUND

Mycoplasma pneumoniae is a major cause of community-acquired pneumonia (CAP) in school-aged children. Macrolides are the first-line treatment for this infection. However, it is unclear whether macrolides are effective in treating M. pneumoniae CAP, mainly due to limitations in microbiological diagnosis of previous studies. The extensive global use of macrolides has led to increasing antimicrobial resistance. The overall objective of this trial is to produce efficacy data for macrolide treatment in children with M. pneumoniae CAP.

METHODS

The MYTHIC Study is a randomized, double-blind, placebo-controlled, multicenter, non-inferiority trial in 13 Swiss pediatric centers. Previously healthy ambulatory and hospitalized children aged 3-17 years with clinically diagnosed CAP will be screened with a sensitive and commercially available M. pneumoniae-specific IgM lateral flow assay from capillary blood. Mycoplasma pneumoniae infection in screened patients will be verified retrospectively by respiratory PCR (reference test) and IgM antibody-secreting cell enzyme-linked immunospot (ELISpot) assay (confirmatory test for distinguishing between carriage and infection). Patients will be randomized 1:1 to receive a 5-day treatment of macrolides (azithromycin) or placebo. The co-primary endpoints are (1) time to normalization of all vital signs, including body temperature, respiratory rate, heart rate, and saturation of peripheral oxygen (efficacy), and (2) CAP-related change in patient care status (i.e., admission, re-admission, or intensive care unit transfer) within 28 days (safety). Secondary outcomes include adverse events (AEs), as well as antimicrobial and anti-inflammatory effects. For both co-primary endpoints, we aim to show non-inferiority of placebo compared to macrolide treatment. We expect no macrolide effect (hazard ratio of 1, absolute risk difference of 0) and set the corresponding non-inferiority margins to 0.7 and -7.5%. The "at least one" success criterion is used to handle multiplicity with the two co-primary endpoints. With a power of 80% to reject at least one null hypothesis at a one-sided significance level of 1.25%, 376 patients will be required.

DISCUSSION

This trial will produce efficacy data for macrolide treatment in children with M. pneumoniae CAP that might help to reduce the prescription of antibiotics and therefore contribute to the global efforts toward reducing antimicrobial resistance.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT06325293. Registered on 24 April 2024.

Combinatorial Host-Response Biomarker Signature (BV Score) and Its Subanalytes TRAIL, IP-10, and C-Reactive Protein in Children With Mycoplasma pneumoniae Community-Acquired Pneumonia

BACKGROUND

Host-response biomarkers to differentiate bacterial from viral etiology in children with respiratory infections have shown high accuracies, but are understudied in Mycoplasma pneumoniae (Mp) infections.

METHODS

We compared BV scores (0-34 indicating viral etiology, and 66-100 indicating bacterial etiology), tumor necrosis factor-related apoptosis-inducing ligand (TRAIL; pg/mL), interferon-γ inducible protein 10 (IP-10; pg/mL), and C-reactive protein (CRP; mg/L) serum levels between Mp-positive (Mp+) and Mp-negative (Mp-) community-acquired pneumonia (CAP) patients. We performed receiver operating characteristic (ROC) curve analyses for clinical features and biomarkers.

RESULTS

Of 80 CAP patients (median age, 6.3 years; 57.5% male), 26 had Mp+CAP. In Mp+CAP patients, compared to Mp-CAP patients, BV scores were lower (14.0 [3.0-27.8] vs 54.0 [12.0-84.8]; P = .0008), TRAIL levels were higher (86.5 [67.4-123.0] vs 65.5 [42.5-103.9]; P = .025), CRP levels were lower (12.9 [4.0-22.3] vs 36.7 [13.0-132.8]; P = .0019), and IP-10 levels were comparable (366.0 [150.2-603.8] vs 331.0 [154.3-878.8]; P = .73) (all median [interquartile range]). ROC analyses yielded a comparable discriminatory accuracy for the combination of age, fever duration, and duration of respiratory symptoms, with either procalcitonin or BV score (area under the ROC curve, 0.87 vs 0.86; P = .94).

CONCLUSIONS

Children with Mp+CAP have atypically low, viral levels of the BV score, underscoring the complementary role of microbiological testing.

Clinical characteristics and changes in serum CXCL10 and CXCL16 levels in patients with severe mycoplasma pneumonia

To explore the clinical characteristics and changes in serum CXCL10 and CXCL16 in patients with severe mycoplasma pneumonia, and to analyze the risk factors of severe mycoplasma pneumonia. About 258 children with acute mycoplasma pneumoniae pneumonia (MPP) admitted to the respiratory department of a certain hospital from January 2020 to December 2022 were selected as the study subjects. According to the severity of MPP, patients are divided into 2 groups, namely the mild illness group (Q group) and the severe illness group (Z group). The number of cases in these 2 groups of children is 167 and 91, respectively. The serum CXCL10, CXCL16, and other indicators of 2 groups are tested. Compared to group Q, patients in group Z have a higher proportion of extrapulmonary complications, longer cough time, longer shortness of breath, and longer wheezing time (P < .05). The serum CXCL16 is higher and the proportion of pleural effusion is higher (P < .01). There are more cases of fever, longer fever duration, longer hospital stay, higher serum CXCL10, and higher D-dimer levels (P < .001). The area under the curve of the probability curve for predicting severe mycoplasma pneumonia is 0.975 (P < .05). Children with severe mycoplasma pneumonia have significantly longer fever duration and hospital stay than those with mild symptoms. The serum levels of CXCL10 and CXCL16 are significantly elevated.

Childhood community-acquired pneumonia

Community-acquired pneumonia (CAP) is a common disease in children, and its aetiological and clinical diagnosis are challenging for physicians in both private practice and hospitals. Over the past three decades, conjugate vaccines have successfully reduced the burden of the former main causes of CAP, Streptococcus pneumoniae and Haemophilus influenzae type b. Today, viruses are by far the most commonly detected pathogens in children with CAP.  Conclusion: New insights into the aetiology and treatment of CAP in children in recent years have influenced management and are the focus of this review. In addition to reducing diagnostic uncertainty, there is an urgent need to reduce antibiotic overuse and antimicrobial resistance in children with CAP. What is Known: • Conjugate vaccines against Streptococcus pneumoniae and Haemophilus influenzae type b have shifted the epidemiology of childhood CAP to predominantly viral pathogens and Mycoplasma pneumoniae. • Clinical, laboratory, and radiological criteria cannot reliably distinguish between bacterial and viral aetiology in children with CAP. What is New: • Test results and epidemiological data must be carefully interpreted, as no single diagnostic method applied to non-pulmonary specimens has both high sensitivity and high specificity for determining pneumonia aetiology in childhood CAP. • This review provides a simple and pragmatic management algorithm for children with CAP to aid physicians in providing optimal and safe care and reducing antibiotic prescribing.

Mycoplasma pneumoniae detections before and during the COVID-19 pandemic: results of a global survey, 2017 to 2021

Background

Mycoplasma pneumoniae respiratory infections are transmitted by aerosol and droplets in close contact.

Aim

We investigated global M. pneumoniae incidence after implementation of non-pharmaceutical interventions (NPIs) against COVID-19 in March 2020.

Methods

We surveyed M. pneumoniae detections from laboratories and surveillance systems (national or regional) across the world from 1 April 2020 to 31 March 2021 and compared them with cases from corresponding months between 2017 and 2020. Macrolide-resistant M. pneumoniae (MRMp) data were collected from 1 April 2017 to 31 March 2021.

Results

Thirty-seven sites from 21 countries in Europe, Asia, America and Oceania submitted valid datasets (631,104 tests). Among the 30,617 M. pneumoniae detections, 62.39% were based on direct test methods (predominantly PCR), 34.24% on a combination of PCR and serology (no distinction between methods) and 3.37% on serology alone (only IgM considered). In all countries, M. pneumoniae incidence by direct test methods declined significantly after implementation of NPIs with a mean of 1.69% (SD ± 3.30) compared with 8.61% (SD ± 10.62) in previous years (p < 0.01). Detection rates decreased with direct but not with indirect test methods (serology) (–93.51% vs + 18.08%; p < 0.01). Direct detections remained low worldwide throughout April 2020 to March 2021 despite widely differing lockdown or school closure periods. Seven sites (Europe, Asia and America) reported MRMp detections in one of 22 investigated cases in April 2020 to March 2021 and 176 of 762 (23.10%) in previous years (p = 0.04).

Conclusions

This comprehensive collection of M. pneumoniae detections worldwide shows correlation between COVID-19 NPIs and significantly reduced detection numbers.

Single-Cell Technologies for the Study of Antibody-Secreting Cells

Antibody-secreting cells (ASC), plasmablasts and plasma cells, are terminally differentiated B cells responsible for large-scale production and secretion of antibodies. ASC are derived from activated B cells, which may differentiate extrafollicularly or form germinal center (GC) reactions within secondary lymphoid organs. ASC therefore consist of short-lived, poorly matured plasmablasts that generally secrete lower-affinity antibodies, or long-lived, highly matured plasma cells that generally secrete higher-affinity antibodies. The ASC population is responsible for producing an immediate humoral B cell response, the polyclonal antibody repertoire, as well as in parallel building effective humoral memory and immunity, or potentially driving pathology in the case of autoimmunity. ASC are phenotypically and transcriptionally distinct from other B cells and further distinguishable by morphology, varied lifespans, and anatomical localization. Single cell analyses are required to interrogate the functional and transcriptional diversity of ASC and their secreted antibody repertoire and understand the contribution of individual ASC responses to the polyclonal humoral response. Here we summarize the current and emerging functional and molecular techniques for high-throughput characterization of ASC with single cell resolution, including flow and mass cytometry, spot-based and microfluidic-based assays, focusing on functional approaches of the secreted antibodies: specificity, affinity, and secretion rate.

The epidemiology, clinical characteristics, and macrolide susceptibility of Mycoplasma pneumoniae pneumonia in children in Southern Taiwan, 2019-2020

BACKGROUND

Since the global use of the pneumococcal conjugate vaccine, Mycoplasma pneumoniae (MP) has become the most common bacterial cause of lower respiratory tract infections among children. Monitoring the changing epidemiology and antimicrobial resistance rates of this organism is important for MP clinical management.

METHODS

This study characterizes key features of MP during the 2019-2020 epidemic in children in Taiwan. The cohort included all hospitalized children under 18 years of age with polymerase chain reaction (PCR)-confirmed community-acquired mycoplasma pneumonia (CAMP) in southern Taiwan. Macrolide resistance was identified by mutations in domain V of MP 23S rRNA. Severe disease referred to symptoms warranting oxygen therapy, septic shock, or intensive care unit admission.

RESULTS

Among 495 LRTI patients, 195 (39.4%) had CAMP, of which 106 (54.4%) had concurrent serological evidence of MP infection. The diagnostic sensitivity of IgM in the acute phase was 65.6%. CAMP case numbers were highest from July 2019 to January 2020. The most common clinical presentations of CAMP were fever (99.0%), cough (99.0%), and coryza (31.8%). Despite a high rate of macrolide resistance (88.1%), macrolide-resistant MP (MRMP) did not differ from macrolide-sensitive MP (MSMP) in clinical course or severity. Delayed administration of effective antimicrobial treatment was also associated with severe disease (p < 0.05).

CONCLUSION

Early diagnosis and determination of MRMP are needed for effective management of MP infection.

Macrolide Resistance, Clinical Features, and Cytokine Profiles in Taiwanese Children With Mycoplasma pneumoniae Infection

Background

The factors that predict the progression of Mycoplasma pneumoniae infection remain inconclusive. Therefore, we investigated macrolide resistance prevalence, M pneumoniae genotype, and clinical characteristics of childhood M pneumoniae respiratory tract infections in Taiwan.

Methods

A total of 295 children hospitalized with respiratory tract infections with positive serological M pneumoniae immunoglobulin M test results were enrolled in this 3-year prospective study. Oropharyngeal swabs were obtained for M pneumoniae cultures and polymerase chain reaction tests. All M pneumoniae specimens were further characterized by P1 typing, multilocus variable-number tandem-repeat analysis (MLVA), and macrolide resistance genotyping. The clinical characteristics and blood cytokine profiles were analyzed accordingly.

Results

Of 138 M pneumoniae specimens, type I P1 was the predominant (136 of 138, 98.6%). The MLVA type P (4-4-5-7-2) was the leading strain (42 of 138, 30.4%), followed by type J, U, A, and X. The overall macrolide-resistant rate was 38.4% (53 of 138); the resistance rate increased dramatically yearly: 10.6% in 2017, 47.5% in 2018, and 62.5% in 2019 (P < .001). All macrolide-resistant M pneumoniae (MRMP) harbored the A2063G mutation and were MLVA type 4-5-7-2 (49 of 53, 92.5%), especially type U and X. No significant differences in clinical symptoms, duration of hospital stay, and radiographic findings were identified among patients between MRMP and macrolide-sensitive M pneumoniae (MSMP) groups. Patients with MRMP infection had more febrile days before and during hospitalization and higher interleukin (IL)-13 and IL-33 levels than patients with MSMP infection (P < .05).

Conclusions

Macrolide-resistant M pneumoniae surged in Taiwan throughout the study period, but macrolide resistance was not a determinant factor of clinical severity.

Mycoplasma pneumoniae carriage evades induction of protective mucosal antibodies

Background

Mycoplasma pneumoniae is the most common bacterial cause of pneumonia in children hospitalised for community-acquired pneumonia (CAP). Prevention of infection by vaccines may be an important strategy in the presence of emerging macrolide-resistant M. pneumoniae. However, knowledge of immune responses to M. pneumoniae is limited, complicating vaccine design.

Methods

We studied the antibody response during M. pneumoniae respiratory tract infection and asymptomatic carriage in two different cohorts.

Results

In a nested case–control study (n=80) of M. pneumoniae carriers and matched controls we observed that carriage by M. pneumoniae does not lead to a rise in either mucosal or systemic M. pneumoniae-specific antibodies, even after months of persistent carriage. We replicated this finding in a second cohort (n=69) and also found that during M. pneumoniae CAP, mucosal levels of M. pneumoniae-specific IgA and IgG did increase significantly. In vitro adhesion assays revealed that high levels of M. pneumoniae-specific antibodies in nasal secretions of paediatric patients prevented the adhesion of M. pneumoniae to respiratory epithelial cells.

Conclusions

Our study demonstrates that M. pneumoniae-specific mucosal antibodies protect against bacterial adhesion to respiratory epithelial cells, and are induced only during M. pneumoniae infection and not during asymptomatic carriage. This is strikingly different from carriage with bacteria such as Streptococcus pneumoniae where mucosal antibodies are induced by bacterial carriage.

Antibodies against M. pneumoniae, the most common bacterial cause of pneumonia in children, are able to prevent adhesion of M. pneumoniae to epithelial cells, but are only induced during infection and not during asymptomatic carriagehttps://bit.ly/3CNdAhM

A potent antibody-secreting B cell response to Mycoplasma pneumoniae in children with pneumonia

BACKGROUND

Mycoplasma pneumoniae is a major pathogen for community-acquired pneumonia and frequently causes outbreaks in children. M. pneumoniae-specific antibody response is detected upon acute infection and the serology is widely used in the clinical setting. Nevertheless, the cellular basis for antigen-specific antibody response to acute M. pneumoniae infection is largely undetermined in children.

METHODS

Hospitalized children with community-acquired pneumonia were enrolled and the infection with M. pneumoniae was confirmed with positive PCR result and negative findings for other pathogens. The M. pneumoniae P1-specific antibody-secreting B cell (ASC) response was examined with the ex vivo enzyme-linked immunosorbent spot assay and the relationships between the ASC frequency and serological level and clinical parameters within M. pneumoniae patients were studied.

RESULTS

A robust M. pneumoniae P1-specific ASC response was detected in the peripheral blood among M. pneumoniae-positive patients. By contrast, no M. pneumoniae-specific ASCs were detected among M. pneumoniae-negative patients. The IgM-secreting B cells are the predominant class and account for over 60% of total circulating M. pneumoniae-specific ASCs in the acute phase of illness. The M. pneumoniae P1-specific ASC frequency significantly correlated with the fever duration, and the IgG ASC frequency significantly correlated with serological titer among patients.

CONCLUSION

A rapid and potent elicitation of peripheral M. pneumoniae-specific ASC response to acute infection provides the cellular basis of antigen-specific humoral response and indicates the potential of cell-based diagnostic tool for acute M. pneumoniae infection. Our findings warrant further investigations into functional and molecular aspects of antibody immunity to M. pneumoniae.

Mycoplasma pneumoniae Genotypes and Clinical Outcome in Children

Factors leading to the wide range of manifestations associated with Mycoplasma pneumoniae infection are unclear. We investigated whether M. pneumoniae genotypes are associated with specific clinical outcomes. We compared M. pneumoniae loads and genotypes of children with mucocutaneous disease to those of children with pneumonia, family members with upper respiratory tract infection (URTI), and carriers from a prospective cohort study (n = 47; 2016 to 2017) and to those of other children with mucocutaneous disease from a case series (n = 7; 2017 to 2020). Genotyping was performed using macrolide resistance determination, P1 subtyping, multilocus variable-number tandem-repeat analysis (MLVA), and multilocus sequence typing (MLST). Comparisons were performed with a pairwise Wilcoxon rank sum test and a Fisher exact test with corrections for multiple testing, as appropriate. M. pneumoniae loads did not statistically differ between patients with mucocutaneous disease and those with pneumonia or carriers. Macrolide resistance was detected in 1 (1.9%) patient with mucocutaneous disease. MLVA types from 2016 to 2017 included 3-5-6-2 (n = 21 [46.7%]), 3-6-6-2 (n = 2 [4.4%]), 4-5-7-2 (n = 14 [31.1%]), and 4-5-7-3 (n = 8 [17.8%]), and they correlated with P1 subtypes and MLST types. MLVA types were not associated with specific outcomes such as mucocutaneous disease, pneumonia, URTI, or carriage. They were almost identical within families but varied over geographic location. MLVA types in patients with mucocutaneous disease differed between 2016 to 2017 (3-5-6-2, n = 5 [62.5%]) and 2017 to 2020 (4-5-7-2, n = 5 [71.4%]) (P = 0.02). Our results suggest that M. pneumoniae genotypes may not determine specific clinical outcomes.

Circulating Antibody-Secreting Cell Response During Mycoplasma pneumoniae Childhood Pneumonia

BACKGROUND

We recently demonstrated that the measurement of Mycoplasma pneumoniae (Mp)-specific immunoglobulin (Ig)M antibody-secreting cells (ASCs) improved diagnosis of Mp infection. Here, we aimed to describe Mp ASC kinetics and duration in comparison to conventional measures such as pharyngeal Mp deoxyribonucleic acid (DNA) and serum antibodies.

METHODS

This is a prospective longitudinal study of 63 community-acquired pneumonia (CAP) patients and 21 healthy controls (HCs), 3-18 years of age, from 2016 to 2017. Mycoplasma pneumoniae ASCs measured by enzyme-linked immunospot assay were assessed alongside Mp DNA and antibodies during 6-month follow-up.

RESULTS

Mycoplasma pneumoniae ASCs of the isotype IgM were found in 29 (46%), IgG were found in 27 (43%), and IgA were found in 27 (43%) CAP patients. Mycoplasma pneumoniae ASCs were detected from 2 days to a maximum of 6 weeks after symptom onset, whereas Mp DNA and antibodies persisted until 4 months (P = .03) and 6 months (P < .01). Mycoplasma pneumoniae ASCs were undetectable in HCs, in contrast to detection of Mp DNA in 10 (48%) or antibodies in 6 (29%) controls for a prolonged time. The Mp ASC response correlated with clinical disease, but it did not differ between patients treated with or without antibiotics against Mp.

CONCLUSIONS

Mycoplasma pneumoniae-specific ASCs are short-lived and associated with clinical disease, making it an optimal resource for determining Mp pneumonia etiology.

Mycoplasma pneumoniae: a pathogen with unsolved therapeutic problems

INTRODUCTION

Despite the amount of new information, the most effective approach for the diagnosis and treatment of Mycoplasma pneumoniae infections is not established. In this narrative review the pharmacological options for macrolide-resistant (ML) M. pneumoniae infections in children are discussed.

AREAS COVERED

Despite significant improvement in the diagnosis and in the definition of diseases potentially associated with this pathogen, not all the problems related to M. pneumoniae infection are solved. True epidemiology of M. pneumoniae diseases and the real role of this pathogen in extra-respiratory manifestations is still unestablished. This reflects on therapy. It is not known whether antibiotics are really needed in all the cases, independently of severity and localization. The choice of antibiotic therapy is debated as it is not known whether ML resistance has clinical relevance. Moreover, not precisely defined is the clinical importance of corticosteroids for improvement of severe cases, including those associated with ML-resistant strains.

EXPERT OPINION

Improvement in M. pneumoniae identification is mandatory to reduce antibiotics overuse , especially in the presence of ML-resistant strains. Priority for future studies includes the evaluation of the true benefit of therapeutic approaches including corticosteroids in patients with severe CAP and in those with extra-respiratory M. pneumoniae diseases.

Acute respiratory distress syndrome during the COVID-19 pandemic: not only SARS-CoV-2

A previously healthy 30-year-old woman developed severe ARDS at the beginning of the COVID-19 pandemic. SARS-CoV-2 infection was suspected, but testing was negative. Mycoplasma pneumoniae was detected by PCR in bronchoalveolar lavage fluid and blood. This case illustrates that M. pneumoniae infection can progress to septicemia and ARDS with severe respiratory failure in young healthy adults.

Randomised placebo-controlled multicentre effectiveness trial of adjunct betamethasone therapy in hospitalised children with community-acquired pneumonia: a trial protocol for the KIDS-STEP trial

INTRODUCTION

Community-acquired pneumonia (CAP) causes around 10 hospitalisations per 1000 child-years, each associated with an average 13 non-routine days experienced and more than 4 parent workdays lost. In adults, steroid treatment shortens time to clinical stabilisation without an increase in complications in patients with CAP. However, despite promising data from observational studies, there is a lack of high-quality evidence for the use of steroids.

METHODS AND ANALYSIS

The KIDS-STEP trial is a multicentre, randomised, double-blind, placebo-controlled superiority trial of betamethasone treatment on outcome of hospitalised children with CAP. Children are enrolled in paediatric emergency departments of hospitals across Switzerland and randomised to adjunct oral betamethasone for 2 days or matching placebo in addition to standard of care treatment. The co-primary outcomes are the proportion of children clinically stable 48 hours after randomisation and the proportion of children with CAP-related readmission within 28 days after randomisation. Secondary outcomes include length of hospital stay, time away from routine childcare and healthcare utilisation and total antibiotic prescriptions within 28 days from randomisation.Each of the co-primary outcomes will be analysed separately. We will test clinical stability rates using a proportion test; to test non-inferiority in readmission rates, we will construct 1-α % CI of the estimated difference and test if it contains the pre-defined margin of 7%. Success is conditional on both tests. A simulation-based sample size estimation determined that recruiting 700 patients will ensure a power of 80% for the study.

ETHICS AND DISSEMINATION

The trial protocol and materials were approved by ethics committees in Switzerland (lead: Ethikkommission Nordwest und Zentralschweiz) and the regulatory authority Swissmedic. Participants and caregivers provide informed consent prior to study procedures commencing. The trial results will be published in peer-reviewed journals and at national and international conferences. Key messages will also be disseminated via press and social media where appropriate.

TRIAL REGISTRATION NUMBER

NCT03474991 and SNCTP000002864.

Frequency and Clinical Presentation of Mucocutaneous Disease Due to Mycoplasma pneumoniae Infection in Children With Community-Acquired Pneumonia

Importance

The diagnosis of Mycoplasma pneumoniae infection as the cause of mucocutaneous disease is challenging because current diagnostic tests are not able to differentiate M pneumoniae infection from carriage.

Objective

To examine the frequency and clinical presentation of M pneumoniae-induced mucocutaneous disease in children with community-acquired pneumonia (CAP) using improved diagnostics.

Design, Setting, and Participants

This prospective, longitudinal cohort study included 152 children aged 3 to 18 years with CAP enrolled in a CAP study from May 1, 2016, to April 30, 2017, at the University Children's Hospital Zurich. Children were inpatients or outpatients with clinically defined CAP according to the British Thoracic Society guidelines. Data analysis was performed from July 10, 2017, to June 29, 2018.

Main Outcomes and Measures

Frequency and clinical presentation of M pneumoniae-induced mucocutaneous disease in childhood CAP. Mycoplasma pneumoniae infection was diagnosed by polymerase chain reaction (PCR) of oropharyngeal samples and confirmed with the measurement of specific peripheral blood IgM antibody-secreting cells by enzyme-linked immunospot assay to differentiate M pneumoniae-infected patients from carriers with CAP caused by other pathogens. Mucocutaneous disease was defined as any eruptive lesion that involved skin and/or mucous membranes occurring during the CAP episode.

Results

Among 152 enrolled children with CAP (median [interquartile range] age, 5.7 [4.3-8.9] years; 84 [55.3%] male), 44 (28.9%) tested positive for M pneumoniae by PCR; of these, 10 children (22.7%) developed mucocutaneous lesions. All 10 patients with mucocutaneous eruptions tested positive for specific IgM antibody-secreting cells. Skin manifestations were found in 3 cases (2.8%) of M pneumoniae PCR-negative CAP (P < .001). The spectrum of M pneumoniae-induced mucocutaneous disease included M pneumoniae-induced rash and mucositis (3 cases [6.8%]), urticaria (2 cases [4.5%]), and maculopapular skin eruptions (5 cases [11.4%]). Two patients had ocular involvement as the sole mucosal manifestation (bilateral anterior uveitis and nonpurulent conjunctivitis). Patients with M pneumoniae-induced mucocutaneous disease had longer duration of prodromal fever (median [interquartile range], 10.5 [8.3-11.8] vs 7.0 [5.5-9.5] days; P = .02) and higher C-reactive protein levels (median [interquartile range], 31 [22-59] vs 16 [7-23] mg/L; P = .04) than patients with CAP due to M pneumoniae without mucocutaneous manifestations. They were also more likely to require oxygen (5 [50%] vs 1 [5%]; P = .007), to require hospitalization (7 [70%] vs 4 [19%]; P = .01), and to develop long-term sequelae (3 [30%] vs 0; P = .03).

Conclusions and Relevance

Mucocutaneous disease occurred significantly more frequently in children with CAP due to M pneumoniae than in children with CAP of other origins. Mycoplasma pneumoniae-induced mucocutaneous disease was associated with increased systemic inflammation, morbidity, and a higher risk of long-term sequelae.

Improved Diagnostics Help to Identify Clinical Features and Biomarkers That Predict Mycoplasma pneumoniae Community-acquired Pneumonia in Children

BACKGROUND

There are no reliable signs or symptoms that differentiate Mycoplasma pneumoniae (Mp) infection in community-acquired pneumonia (CAP) from other etiologies. Additionally, current diagnostic tests do not reliably distinguish between Mp infection and carriage. We previously determined that the measurement of Mp-specific immunoglobulin M antibody-secreting cells (ASCs) by enzyme-linked immunospot assay allowed for differentiation between infection and carriage. Using this new diagnostic test, we aimed to identify clinical and laboratory features associated with Mp infection.

METHODS

This is a prospective cohort study of children, 3-18 years of age, with CAP from 2016 to 2017. Clinical features and biomarkers were compared between Mp-positive and -negative groups by Mann-Whitney U test or Fisher exact test, as appropriate. Area under the receiver operating characteristic curve (AUC) differences and optimal thresholds were determined by using the DeLong test and Youden J statistic, respectively.

RESULTS

Of 63 CAP patients, 29 were Mp-positive (46%). Mp positivity was statistically associated with older age (median, 8.6 vs 4.7 years), no underlying disease, family with respiratory symptoms, prior antibiotic treatment, prolonged prodromal respiratory symptoms and fever, and extrapulmonary (skin) manifestations. Lower levels of C-reactive protein, white blood cell count, absolute neutrophil count, and procalcitonin (PCT), specifically PCT <0.25 μg/L, were statistically associated with Mp infection. A combination of age >5 years (AUC = 0.77), prodromal fever and respiratory symptoms >6 days (AUC = 0.79), and PCT <0.25 μg/L (AUC = 0.81) improved diagnostic performance (AUC = 0.90) (P = .05).

CONCLUSIONS

A combination of clinical features and biomarkers may aid physicians in identifying patients at high risk for Mp CAP.

Reactive infectious mucocutaneous eruption: Mycoplasma pneumoniae-induced rash and mucositis and other parainfectious eruptions

Mycoplasma pneumoniae-induced rash and mucositis is the most accurate diagnosis for patients with blistering mucocutaneous disease provoked by an infection. Recent literature suggests expansion of the name is required, as other infections have caused a clinically similar presentation. This review provides a concise update on current understanding of M. pneumoniae-induced rash and mucositis and other reactive infectious mucocutaneous eruptions.

Pediatric SJS-TEN: Where are we now?

Stevens–Johnson syndrome and toxic epidermal necrolysis are rare severe blistering skin reactions triggered by medications or infections. Over the last 5 to 10 years, a number of important publications have advanced understanding of these diseases and their response to treatment. Importantly, a subset of patients with disease triggered by infection has been identified as having Mycoplasma pneumoniae–induced rash and mucositis, suggesting a reconsideration of the diagnostic paradigm. We present an update on pediatric Stevens–Johnson syndrome and toxic epidermal necrolysis in the broader context of cutaneous adverse drug reactions and focus on challenges and recent advances in diagnosis, management, and prevention.

Mycoplasma pneumoniae-associated mucositis complicated by herpes simplex virus dissemination and Staphylococcus Epidermidis bacteremia

Prominent mucositis with minimal or no cutaneous involvement in the setting of Mycoplasma pneumoniae infection describes a clinical entity recently termed Mycoplasma-induced rash and mucositis (MIRM). About 81% of patients with MIRM experience complete resolution; however, the disease course in approximately 11% of patients is complicated by mucosal sequelae. We describe a patient with MIRM complicated by HSV dissemination and Staphylococcus epidermidis bacteremia and outline the management of mucocutaneous eruptions without systemic immunosuppressant agents.

Paediatric critical illness associated with respiratory infection: a single-centre, retrospective cohort study

OBJECTIVES

To describe critically ill children with respiratory infections, classify them by infection syndrome type and determine the prevalence of Mycoplasma pneumoniae detection.

STUDY DESIGN

A retrospective, single-centre cohort study. All children aged 2 months-18 years with presumed respiratory infection who were admitted to a tertiary hospital paediatric intensive care unit (PICU) between September 2015 and October 2016 were eligible. Subjects were grouped by clinical syndrome (viral respiratory infection, asthma exacerbation, undifferentiated/uncomplicated pneumonia, pneumonia complicated by effusion/empyema and 'other'). All subjects had nasopharyngeal swabs tested for respiratory viruses, M. pneumoniae and Chlamydia pneumoniae.

RESULTS

There were 221 subjects; the median age was 3.1 years; 44% were female; and 78% had medical comorbidities. The majority (75%) was treated with antibiotics, most often ceftriaxone (90% of treated children). Those with any pneumonia were significantly less likely to have a respiratory virus identified in their nasopharynges and had significantly higher C reactive protein (CRP) values than those in the viral infection and asthma groups. There were 10 subjects in whom M. pneumoniae was detected (4.5%, 95% CI 2.2% to 8.2%). Mycoplasma-positive children were older (difference 3.5 years, 95% CI 0.66 to 6.4 years) and had fewer viral coinfections (30% compared with 69%, p=0.02). The prevalence of Mycoplasma infection in children aged >5 years with any pneumonia was 13.2% (95%CI 4.4% to 28%).

CONCLUSIONS

The majority of participants had respiratory viruses detected and were treated with broad-spectrum antibiotics. Differences in CRP and viral prevalence were observed between children with different infection syndrome types. M. pneumoniae infection was not rare in school-aged children with pneumonia admitted to the PICU. Attention to antibiotic treatment and rapid diagnostic testing for Mycoplasma in older, critically ill children should be considered to optimise management and avert morbidity and mortality from respiratory infection.