Carriage of Mycoplasma pneumoniae in the upper respiratory tract of symptomatic and asymptomatic children: an observational study

Laboratory diagnosis and treatment of Mycoplasma pneumoniae infection in children: a review

Mycoplasma pneumoniae (MP) is the cause of Mycoplasma pneumoniae pneumonia (MPP) in children and adolescents, with the clinical manifestations highlighted by intermittent irritating cough, accompanied by headache, fever and muscle pain. This paper aimed to study the research status and focal points in MP infection, especially the common laboratory diagnostic methods and clinical treatment of Mycoplasma pneumoniae. Laboratory diagnostic methods include molecular assay, serological antibody detection, rapid antigen detection and isolation and culture. Polymerase chain reaction (PCR) is the gold standard with high sensitivity and specificity. The serological antibody can detect various immune antibodies qualitatively or quantitatively in serum. Rapid antigen can be detected faster, with no equipment environment requirements, which can be used for the early diagnosis of MP infection. While the culture growth cycle is long and insensitive, not recommended for routine diagnosis. Macrolides were the preferred drug for children with MPP, while the drug resistance rate was rising in China. Tetracycline can be substituted but was not recommended for children under 8 years of age, quinolone drugs are not necessary, severe MPP can be combined with glucocorticoids, involving the nervous or immune system can choose gamma globulin. Other treatments for MPP including symptomatic treatment which can alleviate symptoms, improve lung function and improve prognosis. A safe and effective vaccine needed to be developed which can provide protective immunity to children and will reduce the incidence of MPP.

Position statement of the Spanish Society of Paediatric Infectious diseases on the diagnosis and treatment of Mycoplasma pneumoniae infection

Mycoplasma pneumoniae (M. pneumoniae) is a bacterium with particular characteristics that give rise to a broad clinical spectrum, being respiratory infection the most frequent presentation. Infection by M. pneumoniae occurs in cyclical epidemics, and paediatricians in Spain have noticed an increase in cases since January 2024, establishing hospital registers to collect surveillance data (as it is not a notifiable disease in Spain). The diagnosis of infection by M. pneumoniae is made through serological testing and/or the detection of genetic material by means of polymerase chain reaction (PCR). Neither methods can differentiate between colonization and active infection, so a precise diagnosis is not possible and testing should only be requested in the case of high clinical suspicion. The role of antibiotherapy in infection by M. pneumoniae in its different clinical variants is not well defined. Most infections are self-limiting and mild, and there is insufficient evidence to support the use of antibiotherapy in these cases. Antibiotic treatment is justified in patients with risk factors for the development of severe disease (Down syndrome, anatomical or functional asplenia, immunosuppression), in hospitalized patients with respiratory infection and in patients with moderate or severe extrapulmonary forms. Taking into account aspects concerning the rational use of antimicrobials, the treatment of choice would be clarithromycin, with azithromycin as an alternative, reserving the use of doxycycline and levofloxacin for cases of antimicrobial resistance and/or infections of the central nervous system.

Post COVID-19 Pandemic Increased Detection of Mycoplasma Pneumoniae in Adults Admitted to the Intensive Care

Background: Mycoplasma pneumoniae (M. pneumoniae) infections can progress to severe respiratory complications, necessitating intensive care treatment. Recent post COVID-19 pandemic surges underscore the need for timely diagnosis, given potential diagnostic method limitations. Methods: A retrospective case series analysis was conducted on M. pneumonia PCR-positive patients admitted to two Dutch secondary hospitals' ICUs between January 2023 and February 2024. Clinical presentations, treatments, outcomes, and mechanical ventilation data were assessed. Results: Seventeen ICU-admitted patients were identified, with a median age of 44 years, primarily due to hypoxia. Non-invasive ventilation was effective for most, while five required invasive mechanical ventilation. None of the patients required extracorporeal membrane oxygenation. No fatalities occurred. Post-PCR, treatment was adjusted to doxycycline or azithromycin; seven received steroid treatment. Discussion: Increased ICU admissions for M. pneumoniae infection were observed. Diverse clinical and radiological findings emphasize heightened clinical awareness. Early molecular diagnostics and tailored antibiotic regimens are crucial since beta-lactam antibiotics are ineffective. Conclusion: This study highlights the escalating challenge of severe M. pneumoniae infections in ICUs, necessitating a multifaceted approach involving accurate diagnostics, vigilant monitoring, and adaptable treatment strategies for optimal patient outcomes.

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.

Increased incidence of Mycoplasma pneumoniae infections and hospital admissions in the Netherlands, November to December 2023

Mycoplasma pneumoniae is an important cause of pneumonia and extra-pulmonary manifestations. We observed a rise in admissions due to M. pneumoniae infections starting October 2023 in a regional hospital in the Netherlands and an increased incidence in national surveillance data. The incidence in the Netherlands has not been that high since 2011. The patients had a lower median age compared with 2019 and 2020 (28 vs 40 years). M. pneumoniae should be considered in patients with respiratory symptoms, especially children.

Unique Changes in the Incidence of Acute Chest Syndrome in Children With Sickle Cell Disease Unravel the Role of Respiratory Pathogens: A Time Series Analysis

BACKGROUND

Acute chest syndrome (ACS) is a life-threatening complication of sickle cell disease (SCD). Although respiratory pathogens are frequently detected in children with ACS, their respective role in triggering the disease is still unclear. We hypothesized that the incidence of ACS followed the unprecedented population-level changes in respiratory pathogen dynamics after COVID-19-related nonpharmaceutical interventions (NPIs).

RESEARCH QUESTION

What is the respective role of respiratory pathogens in ACS epidemiology?

STUDY DESIGN AND METHODS

This study was an interrupted time series analysis of patient records from a national hospital-based surveillance system. All children aged < 18 years with SCD hospitalized for ACS in France between January 2015 and May 2022 were included. The monthly incidence of ACS per 1,000 children with SCD over time was analyzed by using a quasi-Poisson regression model. The circulation of 12 respiratory pathogens in the general pediatric population over the same period was included in the model to assess the fraction of ACS potentially attributable to each respiratory pathogen.

RESULTS

Among the 55,941 hospitalizations of children with SCD, 2,306 episodes of ACS were included (median [interquartile range] age, 9 [5-13] years). A significant decrease was observed in ACS incidence after NPI implementation in March 2020 (-29.5%; 95% CI, -46.8 to -12.2; P = .001) and a significant increase after lifting of the NPIs in April 2021 (24.4%; 95% CI, 7.2 to 41.6; P = .007). Using population-level incidence of several respiratory pathogens, Streptococcus pneumoniae accounted for 30.9% (95% CI, 4.9 to 56.9; P = .02) of ACS incidence over the study period and influenza 6.8% (95% CI, 2.3 to 11.3; P = .004); other respiratory pathogens had only a minor role.

INTERPRETATION

NPIs were associated with significant changes in ACS incidence concomitantly with major changes in the circulation of several respiratory pathogens in the general population. This unique epidemiologic situation allowed determination of the contribution of these respiratory pathogens, in particular S pneumoniae and influenza, to the burden of childhood ACS, highlighting the potential benefit of vaccine prevention in this vulnerable population.

A Case of Mycoplasma Infection with an Atypical Presentation of Abducens Nerve Palsy, Erythema Multiforme and Polyarthritis without Respiratory Manifestations

Mycoplasma pneumoniae is a self-propagating microorganism that commonly causes respiratory tract infections. It can also cause a variety of extrapulmonary symptoms with or independently of respiratory symptoms, such as skin lesions, arthralgia, myalgia, hemolysis, cardiac lesions, gastrointestinal symptoms, and central nervous system lesions, which are rare manifestations reported in approximately 0.1% of cases. In this study, we present a unique case of Mycoplasma-related abducens nerve palsy, polyarthritis, and erythema multiforme without respiratory disease. The patient was a 69-year-old woman who presented to our hospital with a skin rash, fever, arthralgia, and diplopia without respiratory symptoms. Brain magnetic resonance imaging showed optic neuritis on the right side, suggesting the diplopia was caused by right abducens nerve palsy. However, the etiologies of abducens nerve palsy were not revealed by the physical examination, blood biochemistry tests, or bacteriological examinations, including the cerebrospinal fluid examination obtained at admission. Mycoplasma infection was suspected from erythema multiforme revealed by a skin biopsy and polyarthralgia, and it was finally diagnosed according to elevated Mycoplasma particle agglutination (PA) antibodies in paired serum. Though minocycline did not improve her diplopia, the daily administration of 30 mg of prednisolone gradually improved her symptoms, and the Mycoplasma PA antibody titer, which was regularly measured in the clinical course, also decreased, suggesting a relationship between Mycoplasma infection and abducens nerve palsy. This is the first case of isolated abducens nerve palsy, which was reported as the only central neurological symptom in an adult patient with Mycoplasma infection. The mechanism or pathogenesis of CNS manifestations caused by Mycoplasma pneumoniae remains to be elucidated, and further investigation is needed. Hence, Mycoplasma infection is a common disease. Clinicians should be aware of the diverse manifestations, including abducens nerve palsy, of Mycoplasma infection and should consider Mycoplasma infection even in the absence of typical respiratory symptoms.

Mycoplasma pneumoniae carriage in children with recurrent respiratory tract infections is associated with a less diverse and altered microbiota

BACKGROUND

Mycoplasma pneumoniae is a common cause of community-acquired pneumonia in school-aged children and can be preceded by asymptomatic carriage. However, its role in recurrent respiratory tract infections is unclear. We studied the prevalence of M.pneumoniae carriage in children with recurrent respiratory infections and identified associated factors.

METHODS

We tested M.pneumoniae carriage by qPCR in children with recurrent infections and their healthy family members in a cross-sectional study. Serum and mucosal total and M.pneumoniae-specific antibody levels were measured by ELISA and nasopharyngeal microbiota composition was characterized by 16S-rRNA sequencing.

FINDINGS

Prevalence of M.pneumoniae carriage was higher in children with recurrent infections (68%) than their family members without infections (47% in siblings and 27% in parents). M.pneumoniae carriage among family members appeared to be associated with transmission within the household, likely originating from the affected child. In logistic regression corrected for age and multiple comparisons, IgA (OR 0.16 [0.06-0.37]) and total IgG deficiency (OR 0.15 [0.02-0.74]) were less prevalent in M.pneumoniae carriers (n = 78) compared to non-carriers (n = 36). In multivariable analysis, the nasopharyngeal microbiota of M.pneumoniae carriers had lower alpha diversity (OR 0.27 [0.09-0.67]) and a higher abundance of Haemophilus influenzae (OR 45.01 [2.74-1608.11]) compared to non-carriers.

INTERPRETATION

M.pneumoniae carriage is highly prevalent in children with recurrent infections and carriers have a less diverse microbiota with an overrepresentation of disease-associated microbiota members compared to non-carriers. Given the high prevalence of M.pneumoniae carriage and the strong association with H. influenzae, we recommend appropriate antibiotic coverage of M.pneumoniae and H. influenzae in case of suspected pneumonia in children with recurrent respiratory tract infections or their family members.

FUNDING

Wilhelmina Children's Hospital Research Fund, 'Christine Bader Stichting Irene KinderZiekenhuis', Sophia Scientific Research Foundation, ESPID Fellowship funded by Seqirus, Hypatia Fellowship funded by Radboudumc and The Netherlands Organisation for Health Research and Development (ZonMW VENI grant to LM Verhagen).

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.

Tracking severe acute respiratory syndrome coronavirus 2 transmission and co-infection with other acute respiratory pathogens using a sentinel surveillance system in Rift Valley, Kenya

BACKGROUND

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been the most significant public health challenge in over a century. SARS-CoV-2 has infected over 765 million people worldwide, resulting in over 6.9 million deaths. This study aimed to detect community transmission of SARS-CoV-2 and monitor the co-circulation of SARS-CoV-2 with other acute respiratory pathogens in Rift Valley, Kenya.

METHODS

We conducted a cross-sectional active sentinel surveillance for the SARS-CoV-2 virus among patients with acute respiratory infections at four sites in Rift Valley from January 2022 to December 2022. One thousand two hundred seventy-one patients aged between 3 years and 98 years presenting with influenza-like illness (ILI) were recruited into the study. Nasopharyngeal swab specimens from all study participants were screened using a reverse transcription-quantitative polymerase chain reaction (RT-qPCR) for SARS-CoV-2, influenza A, influenza B and respiratory syncytial virus (RSV).

RESULTS

The samples that tested positive for influenza A (n = 73) and RSV (n = 12) were subtyped, while SARS-CoV-2 (n = 177) positive samples were further screened for 12 viral and seven bacterial respiratory pathogens. We had a prevalence of 13.9% for SARS-CoV-2, 5.7% for influenza A, 2% for influenza B and 1% for RSV. Influenza A-H1pdm09 and RSV B were the most dominant circulating subtypes of influenza A and RSV, respectively. The most common co-infecting pathogens were Streptococcus pneumoniae (n = 29) and Haemophilus influenzae (n = 19), accounting for 16.4% and 10.7% of all the SARS-CoV-2 positive samples.

CONCLUSIONS

Augmenting syndromic testing in acute respiratory infections (ARIs) surveillance is crucial to inform evidence-based clinical and public health interventions.

Comparison of serodiagnosis methods for community-acquired Mycoplasma pneumoniae respiratory tract infections in children

This study aimed to evaluate the diagnostic value of chemiluminescence immunoassay (CLIA), passive particle agglutination (PPA), and indirect immunofluorescence assay (IFA) in detecting Mycoplasma pneumoniae infection in children. Serum samples from 165 children with acute community-acquired respiratory tract infections were examined using CLIA, PPA, and IFA, and consistency coefficient, specificity, and sensitivity were analyzed. Compared with the PPA (titer ≥ 1:160), the consistency coefficients of the immunoglobulin(Ig)M-CLIA, immunoglobulin(Ig)G-CLIA and IgM-IFA methods were 93.94%, 75.76%, and 83.64%, respectively. The positive likelihood ratio (PLR) and specificity of IgM-CLIA was 19.40 and 95.49%, respectively. The consistency coefficient of (IgM+IgG)-CLIA and PPA (titer ≥ 1:160) was 89.1%, and the sensitivity and negative predictive value of (IgM+IgG)-CLIA were 96.88% and 98.94%, respectively. CLIA MP-IgM has high concordance with PPA, and its specificity and sensitivity are higher than those of CLIA MP-IgG and IFA MP-IgM, suggesting its better diagnosis of early MP infection. The sensitivity and negative predictive value of CLIA MP (IgM+IgG) were higher than those of PPA or IFA, indicating that it should be considered as a priority in the diagnosis of MP infection.

Absolute quantification of Mycoplasma pneumoniae in infected patients by droplet digital PCR to track disease severity and treatment efficacy

Mycoplasma pneumoniae is a common causative pathogen of community-acquired pneumonia. An accurate and sensitive detection method is important for evaluating disease severity and treatment efficacy. Digital droplet PCR (ddPCR) is a competent method enabling the absolute quantification of DNA copy number with high precision and sensitivity. We established ddPCR for M. pneumoniae detection, using clinical specimens for validation, and this showed excellent specificity for M. pneumoniae. The limit of detection of ddPCR was 2.9 copies/reaction, while that for real-time PCR was 10.8 copies/reaction. In total, 178 clinical samples were used to evaluate the ddPCR assay, which correctly identified and differentiated 80 positive samples, whereas the real-time PCR tested 79 samples as positive. One sample that tested negative in real-time PCR was positive in ddPCR, with a bacterial load of three copies/test. For samples that tested positive in both methods, the cycle threshold of real-time PCR was highly correlated with the copy number of ddPCR. Bacterial loads in patients with severe M. pneumoniae pneumonia were significantly higher than those in patients with general M. pneumoniae pneumonia. The ddPCR showed that bacterial loads were significantly decreased after macrolide treatment, which could have reflected the treatment efficacy. The proposed ddPCR assay was sensitive and specific for the detection of M. pneumoniae. Quantitative monitoring of bacterial load in clinical samples could help clinicians to evaluate treatment efficacy.

Clinical, Laboratory, and Radiographic Features Can Help Predict Mycoplasma pneumoniae Lower Respiratory Tract Infection in Children

Mycoplasma pneumoniae (Mp) is a common cause of lower respiratory tract infection (LRTI) in children that is difficult to distinguish from LRTI of other etiologies. We aimed to determine if a combination of clinical, laboratory, and chest radiographic features can help identify patients at higher risk of Mp LRTI. We reviewed medical charts of children referred to our tertiary hospital with suspected acute mycoplasmal LRTI. Pharyngeal swabs obtained from patients were tested by Mp PCR. We compared epidemiological and clinical data of children with positive and negative Mp PCR results. In addition, a multivariable logistic regression analysis was performed to predict Mp LRTI based on the patient's age, duration of symptoms, presence of extrapulmonary manifestations, laboratory findings, and chest radiographic findings. We included 65 children with Mp PCR-negative and 49 with Mp PCR-positive LRTI and no viral co-detection. Children with Mp LRTI were older (median age 5.8 vs. 2.2 years, p < 0.001), had a longer duration of symptoms on referral (median 7 vs. 4 days, p < 0.001), and lower median WBC (9.9 vs. 12.7 × 10⁹/L, p < 0.001). On chest radiograph, unilateral infiltrates were more frequently observed in the Mp PCR-positive group (57.5% vs. 24.1%, p = 0.001). Age, duration of symptoms, and chest radiographic findings had the highest predictive value for Mp LRTI in a multivariable logistic regression model. Our analysis suggests that a combination of clinical, laboratory, and chest radiographic features can be used to assess the likelihood of Mp LRTI and assist in decision-making for which children need further tests or macrolide antibiotic treatment.

Novel mechanisms of macrolide resistance revealed by in vitro selection and genome analysis in Mycoplasma pneumoniae

Mycoplasma pneumoniae is an important pathogen causing upper and lower respiratory tract infections in children and other age groups. Macrolides are the recommended treatments of choice for M. pneumoniae infections. However, macrolide resistance in M. pneumoniae is increasing worldwide, which complicates the treatment strategies. The mechanisms of macrolide resistance have been extensively studied focusing on the mutations in 23S rRNA and ribosomal proteins. Since the secondary treatment choice for pediatric patients is very limited, we decided to look for potential new treatment strategies in macrolide drugs and investigate possible new mechanisms of resistance. We performed an in vitro selection of mutants resistant to five macrolides (erythromycin, roxithromycin, azithromycin, josamycin, and midecamycin) by inducing the parent M. pneumoniae strain M129 with increasing concentrations of the drugs. The evolving cultures in every passage were tested for their antimicrobial susceptibilities to eight drugs and mutations known to be associated with macrolide resistance by PCR and sequencing. The final selected mutants were also analyzed by whole-genome sequencing. Results showed that roxithromycin is the drug that most easily induces resistance (at 0.25 mg/L, with two passages, 23 days), while with midecamycin it is most difficult (at 5.12 mg/L, with seven passages, 87 days). Point mutations C2617A/T, A2063G, or A2064C in domain V of 23S rRNA were detected in mutants resistant to the 14- and 15-membered macrolides, while A2067G/C was selected for the 16-membered macrolides. Single amino acid changes (G72R, G72V) in ribosomal protein L4 emerged during the induction by midecamycin. Genome sequencing identified sequence variations in dnaK, rpoC, glpK, MPN449, and in one of the hsdS (MPN365) genes in the mutants. Mutants induced by the 14- or 15-membered macrolides were resistant to all macrolides, while those induced by the 16-membered macrolides (midecamycin and josamycin) remained susceptible to the 14- and 15-membered macrolides. In summary, these data demonstrated that midecamycin is less potent in inducing resistance than other macrolides, and the induced resistance is restrained to the 16-membered macrolides, suggesting a potential benefit of using midecamycin as a first treatment choice if the strain is susceptible.

Galacto-Oligosaccharides as an Anti-Infective and Anti-Microbial Agent for Macrolide-Resistant and -Sensitive Mycoplasma pneumoniae

The worldwide increase in the incidence of antibiotic resistance of the atypical bacterium Mycoplasma pneumoniae (MP) challenges the treatment of MP infections, especially in children. Therefore, alternative strategies for the treatment of MP infections are warranted. Galacto- and fructo-oligosaccharides (GOS and FOS) are a specific group of complex carbohydrates that were recently shown to possess direct anti-pathogenic properties. In this study, we assessed whether GOS and FOS exert anti-microbial and anti-infective effects against MP and, especially, macrolide-resistant MP (MRMP) in vitro. The MIC values of GOS for MP and MRMP were 4%. In contrast, the MIC values of FOS for both MP and MRMP were 16%. A time-kill kinetic assay showed that FOS possess bacteriostatic properties, while for GOS, a bactericidal effect against MP and MRMP was observed after 24 h at a concentration of 4x MIC. In co-cultures with human alveolar A549 epithelial cells, GOS killed adherent MP and MRMP and also concentration-dependently inhibited their adherence to A549 cells. Further, GOS suppressed (MR)MP-induced IL-6 and IL-8 in A549 cells. None of the aforementioned parameters were affected when FOS were added to these co-cultures. In conclusion, the anti-infective and anti-microbial properties of GOS could provide an alternative treatment against MRMP and MP infections.

Nasopharyngeal detection of atypical bacteria by multiplex polymerase chain reaction panel in acutely ill children was associated with an increased risk of pneumonia

AIM

We aimed to assess whether detection of respiratory bacteria by multiplex polymerase chain reaction (PCR) testing associates with clinical outcomes in acutely ill children.

METHODS

This cross-sectional study enrolled children under the age of 18 with a suspected respiratory infection treated in a paediatric emergency department of Oulu University Hospital, Finland from January 2015 through December 2015. Nasopharyngeal samples were routinely analysed for 16 respiratory viruses and later, after storage, analysed with a multiplex PCR panel for seven respiratory bacteria.

RESULTS

At least one bacterial pathogen was detected in 600 out of the 1195 children (50%). The mean age was 3.3 (SD 3.7) years and 54% were boys. Atypical bacteria were associated with a risk of pneumonia (adjusted odds ratio [aOR] 14.1, 95% CI 3.98-50.1). Co-detection of rhinovirus with Streptococcus pneumoniae was not associated with risk of pneumonia (aOR 2.39, 95% CI 0.78-7.30). Detection of Streptococcus pneumoniae, Haemophilus influenzae or both was not associated with the risk of hospital admission or prescription of antibiotics.

CONCLUSION

Nasopharyngeal detection of atypical bacteria in acutely ill children was associated with a markedly increased risk of pneumonia. The clinical utility of wide testing for other respiratory bacteria needs further evaluation.

Pathogen spectra in hospitalised and nonhospitalised children with community-acquired pneumonia

Background

Paediatric community-acquired pneumonia (CAP) is a leading cause of paediatric morbidity. However, particularly for outpatients with paediatric CAP, data on aetiology and management are scarce.

Methods

The prospective pedCAPNETZ study multicentrically enrols children and adolescents with outpatient-treated or hospitalised paediatric CAP in Germany. Blood and respiratory specimens were collected systematically, and comprehensive analyses of pathogen spectra were conducted. Follow-up evaluations were performed until day 90 after enrolment.

Results

Between December 2014 and August 2020, we enrolled 486 children with paediatric CAP at eight study sites, 437 (89.9%) of whom had radiographic evidence of paediatric CAP. Median (interquartile range) age was 4.5 (1.6-6.6) years, and 345 (78.9%) children were hospitalised. The most prevalent symptoms at enrolment were cough (91.8%), fever (89.2%) and tachypnoea (62.0%). Outpatients were significantly older, displayed significantly lower C-reactive protein levels and were significantly more likely to be symptom-free at follow-up days 14 and 90. Pathogens were detected in 90.3% of all patients (one or more viral pathogens in 68.1%; one or more bacterial strains in 18.7%; combined bacterial/viral pathogens in 4.1%). Parainfluenza virus and Mycoplasma pneumoniae were significantly more frequent in outpatients. The proportion of patients with antibiotic therapy was comparably high in both groups (92.4% of outpatients versus 86.2% of hospitalised patients).

Conclusion

We present first data on paediatric CAP with comprehensive analyses in outpatients and hospitalised cases and demonstrate high detection rates of viral pathogens in both groups. Particularly in young paediatric CAP patients with outpatient care, antibiotic therapy needs to be critically debated.

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.

Modern approaches at the management of children with community-acquired pneumonia

Experts of The Union of Pediatricians of Russia have developed current clinical guidelines for management of children with community-acquired pneumonia, which were approved by the Scientific and Practice Council of Ministry of Public Health of the Russian Federation in January 2022. Particular attention is paid to the etiological structure, modern classification, diagnostic tests and flagship approaches to antibacterial therapy of community-acquired pneumonia in children based on the principles of evidentiary medicine. 

The Contribution of Viruses and Bacteria to Childhood Community-acquired Pneumonia: 11-Year Observational Study From Norway

BACKGROUND

Viruses are associated with pediatric community-acquired pneumonia (CAP) but are also common in the upper airways of healthy children. We have determined the contribution of respiratory viruses and bacteria by comparing children with CAP and hospital controls.

METHODS

Children less than 16 years old with radiologically confirmed CAP (n = 715) were enrolled over an 11-year period. Children admitted for elective surgery during the same period served as controls (n = 673). Nasopharyngeal aspirates were tested for 20 respiratory pathogens by semiquantitative polymerase chain reaction tests and cultivated for bacteria and viruses. We used logistic regression to calculate adjusted odds ratios [aOR; 95% confidence intervals (CIs)], and estimated population-attributable fractions (95% CI).

RESULTS

At least 1 virus was detected in 85% of cases and 76% of controls, and greater than or equal to 1 bacterium was detected in 70% of cases and controls. The presence of respiratory syncytial virus (RSV) (aOR, 16.6; 95% CI: 9.81-28.2), human metapneumovirus (HMPV) (13.0; 6.17-27.5) and Mycoplasma pneumonia e (27.7; 8.37-91.6) were most strongly associated with CAP. For RSV and HMPV, there were significant trends between lower cycle-threshold values indicating higher viral genomic loads, and higher aORs for CAP. The population-attributable fraction estimates of RSV, HMPV, human parainfluenza virus, influenza virus and M. pneumoniae were 33.3% (32.2-34.5), 11.2% (10.5-11.9), 3.7% (1.0-6.3), 2.3% (1.0-3.6) and 4.2% (4.1-4.4), respectively.

CONCLUSIONS

RSV, HMPV and M. pneumoniae were most strongly related to pediatric CAP and accounted for half of all cases. There were positive trends between increasing viral genomic loads of RSV and HMPV, and higher odds for CAP.

Atypical Pathogens in Adult Community-Acquired Pneumonia and Implications for Empiric Antibiotic Treatment: A Narrative Review

Atypical pathogens are intracellular bacteria causing community-acquired pneumonia (CAP) in a significant minority of patients. Legionella spp., Chlamydia pneumoniae and psittaci, Mycoplasma pneumoniae, and Coxiella burnetii are commonly included in this category. M. pneumoniae is present in 5-8% of CAP, being the second most frequent pathogen after Streptococcus pneumoniae. Legionella pneumophila is found in 3-5% of inpatients. Chlamydia spp. and Coxiella burnetii are present in less than 1% of patients. Legionella longbeachae is relatively frequent in New Zealand and Australia and might also be present in other parts of the world. Uncertainty remains on the prevalence of atypical pathogens, due to limitations in diagnostic means and methodological issues in epidemiological studies. Despite differences between CAP caused by typical and atypical pathogens, the clinical presentation alone does not allow accurate discrimination. Hence, antibiotics active against atypical pathogens (macrolides, tetracyclines and fluoroquinolones) should be included in the empiric antibiotic treatment of all patients with severe CAP. For patients with milder disease, evidence is lacking and recommendations differ between guidelines. Use of clinical prediction rules to identify patients most likely to be infected with atypical pathogens, and strategies of narrowing the antibiotic spectrum according to initial microbiologic investigations, should be the focus of future investigations.

Development of a model for early differentiation of adenovirus pneumonia from Mycoplasma pneumoniae pneumonia

BACKGROUND

Adenovirus pneumonia (AVP) and Mycoplasma pneumoniae pneumonia (MPP) have similar clinical manifestations such as a high prevalence of lung consolidation, making the differential diagnosis difficult before the etiology is reported. This study aimed to compare AVP and MPP, and to build a predictive model to differentiate them early.

METHODS

We selected 198 cases of AVP and 876 cases of MPP. Clinical manifestations, computed tomography (CT) features, and biomarkers were compared. A logistic regression model was built to predict AVP. The area under the curve (AUC) of the receiver-operating characteristic was calculated to evaluate the discriminant ability of the prediction model.

RESULTS

Patients in the AVP group were mainly infants and toddlers, while the MPP group had more pre-school age children. The rate of hypoxemia and severe pneumonia was 3- and 11-times higher, respectively, in the AVP group than in the MPP group (5.6% vs. 1.8%, 27.8% vs. 2.5%, P<0.01). The proportion of patients with a Pediatric Logistic Organ Dysfunction-2 score ≥2 was 10 times higher in the AVP group than in the MPP group (17.4% vs. 1.7%, P<0.01). Bilateral pneumonia was present in 90.2% of the AVP group. Biomarkers, such as interleukin (IL)-2 receptor, IL-10 and lactic dehydrogenase (LDH), were considerably higher in the AVP group than in the MPP group (P<0.01). The predictive model included eight variables, namely: age, severe pneumonia, bilateral pneumonia, ground-glass attenuation, consolidation, atelectasis, C-reactive protein, and LDH. The AUC was 86.6%.

CONCLUSIONS

Compared with MPP, AVP affects younger children, presents a more severe respiratory tract involvement, results in a larger range of lung lesions, and is associated with higher inflammatory biomarkers. Our predictive model includes a combination of clinical features, imaging findings, and biomarkers. It may help pediatricians in the early differentiation of AVP from MPP.

Antimicrobial Susceptibility Profiles and Genetic Characteristics of Mycoplasma pneumoniae in Shanghai, China, from 2017 to 2019

Objective

The current study investigated the recent genetic characteristics and antimicrobial susceptibility profiles of Mycoplasma pneumoniae (M. pneumoniae) in Shanghai, becoming a clinical reference for treating M. pneumoniae infection in Shanghai.

Methods

Clinical strains were isolated from nasopharyngeal aspirates of the pediatric patients in Shanghai from 2017 to 2019. Nine antimicrobial agents of three antimicrobial classes macrolides, fluoroquinolones and tetracyclines, against M. pneumoniae isolates were investigated using the broth microdilution method. The mechanism of macrolide resistance was analyzed by evaluating the sequences of the 23S rRNA gene and the ribosomal protein genes L4 and L22. Molecular genotyping was undergone to classify the P1 subtypes and the multi-locus variable-number tandem-repeat analysis (MLVA) types.

Results

A total of 72 isolates were resistant to macrolides (MICs > 64 mg/L for erythromycin) based on the A2063G mutation in the 23S rRNA gene. These strains were susceptible to tetracyclines and fluoroquinolones. P1 type 1 (166/182, 91.2%) and MLVA type 4-5-7-2 (165/182, 90.7%) were the dominant subtypes. MLVA type was associated with the P1 subtypes. The distribution of the P1 subtypes and MLVA types did not change over time. The macrolide-resistant rate in P1 type 2 and MLVA type 3-5-6-2 strains were increased during the three-year study. The 5-loci MLVA typing scheme revealed the clonal expansion of MLVA type 3-4-5-7-2 strains which are macrolide-resistant in 2019.

Conclusion

Macrolide resistance in M. pneumoniae in Shanghai is very high and is evolving among certain subtypes. Cautions should be taken for the possible clonal spreading of macrolide-resistant genotypes within this populated region.

Mycoplasma pneumoniae Compared to Streptococcus pneumoniae Avoids Induction of Proinflammatory Epithelial Cell Responses despite Robustly Inducing TLR2 Signaling

Mycoplasma pneumoniae and Streptococcus pneumoniae are the most common bacterial causes of pneumonia in children. The clinical characteristics of pneumonia differ significantly between the two bacteria. We aimed to elucidate the differences in pathogenesis between M. pneumoniae and S. pneumoniae by characterizing the respiratory epithelial cell immune response to both pathogens. Using primary human bronchial epithelial cells in air-liquid interface cultures, we observed lower production of the proinflammatory cytokines interleukin-6 (IL-6) and IL-8 in response to M. pneumoniae than to S. pneumoniae. In contrast to the differences in proinflammatory cytokine production, Toll-like receptor 2 (TLR2)-mediated signaling in response to M. pneumoniae was stronger than to S. pneumoniae. This difference largely depended on TLR1 and not TLR6. We found that M. pneumoniae, but not S. pneumoniae, also induced signaling of TLR10, a coreceptor of TLR2 that has inhibitory properties. M. pneumoniae-induced TLR10 signaling on airway epithelial cells was partially responsible for low IL-8 production, as blocking TLR10 by specific antibodies increased cytokine production. M. pneumoniae maintained Th2-associated cytokine production by epithelial cells, which concurs with the known association of M. pneumoniae infection with asthma. M. pneumoniae left IL-33 levels unchanged, whereas S. pneumoniae downregulated IL-33 production both under homeostatic and Th2-promoting conditions. By directly comparing M. pneumoniae and S. pneumoniae, we demonstrate that M. pneumoniae avoids induction of proinflammatory cytokine response despite its ability to induce robust TLR2 signaling. Our new findings suggest that this apparent paradox may be partially explained by M. pneumoniae-induced signaling of TLR2/TLR10.

Vaccination with Mycoplasma pneumoniae membrane lipoproteins induces IL-17A driven neutrophilia that mediates Vaccine-Enhanced Disease

Bacterial lipoproteins are an often-underappreciated class of microbe-associated molecular patterns with potent immunomodulatory activity. We previously reported that vaccination of BALB/c mice with Mycoplasma pneumoniae (Mp) lipid-associated membrane proteins (LAMPs) resulted in lipoprotein-dependent vaccine enhanced disease after challenge with virulent Mp, though the immune responses underpinning this phenomenon remain poorly understood. Herein, we report that lipoprotein-induced VED in a mouse model is associated with elevated inflammatory cytokines TNF-α, IL-1β, IL-6, IL-17A, and KC in lung lavage fluid and with suppurative pneumonia marked by exuberant neutrophilia in the pulmonary parenchyma. Whole-lung-digest flow cytometry and RNAScope analysis identified multiple cellular sources for IL-17A, and the numbers of IL-17A producing cells were increased in LAMPs-vaccinated/Mp-challenged animals compared to controls. Specific IL-17A or neutrophil depletion reduced disease severity in our VED model—indicating that Mp lipoproteins induce VED in an IL-17A-dependent manner and through exuberant neutrophil recruitment. IL-17A neutralization reduced levels of TNF-α, IL-1β, IL-6, and KC, indicating that IL-17A preceded other inflammatory cytokines. Surprisingly, we found that IL-17A neutralization impaired bacterial clearance, while neutrophil depletion improved it—indicating that, while IL-17A appears to confer both maladaptive and protective responses, neutrophils play an entirely maladaptive role in VED. Given that lipoproteins are found in virtually all bacteria, the potential for lipoprotein-mediated maladaptive inflammatory responses should be taken into consideration when developing vaccines against bacterial pathogens.

Molecular Tools for Typing Mycoplasma pneumoniae and Mycoplasma genitalium

Mycoplasma pneumoniae and Mycoplasma genitalium are cell wall-less bacteria with strongly reduced genome content and close phylogenetic relatedness. In humans, the only known natural host, the microorganisms colonize the respiratory or genitourinary mucosa and may cause a broad range of clinical presentations. Besides fundamental differences in their tissue specificity, transmission route, and ability to cause prevalence peaks, both species share similarities such as the occurrence of asymptomatic carriers, preferred populations for infection, and problems with high rates of antimicrobial resistance. To further understand the epidemiology of these practically challenging bacteria, typing of strains is necessary. Since the cultivation of both pathogens is difficult and not performed outside of specialized laboratories, molecular typing methods with adequate discriminatory power, stability, and reproducibility have been developed. These include the characterization of genes containing repetitive sequences, of variable genome regions without the presence of repetitive sequences, determination of single and multi-locus variable-number tandem repeats, and detection of single nucleotide polymorphisms in different genes, respectively. The current repertoire of procedures allows reliable differentiation of strains circulating in different populations and in different time periods as well as comparison of strains occurring subsequently in individual patients. In this review, the methods for typing M. pneumoniae and M. genitalium, including the results of their application in different studies, are summarized and current knowledge regarding the association of typing data with the clinical characteristics of infections is presented.

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.

Refractory Mycoplasma pneumoniae Pneumonia in Children: Early Recognition and Management

Refractory Mycoplasma pneumoniae pneumonia (RMPP) is a severe state of M. pneumoniae infection that has attracted increasing universal attention in recent years. The pathogenesis of RMPP remains unknown, but the excessive host immune responses as well as macrolide resistance of M. pneumoniae might play important roles in the development of RMPP. To improve the prognosis of RMPP, it is mandatory to recognize RMPP in the early stages, and the detection of macrolide-resistant MP, clinical unresponsiveness to macrolides and elevated proinflammatory cytokines might be clues. Timely and effective anti-mycoplasmal therapy and immunomodulating therapy are the main strategies for RMPP.

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.

Clinical Characteristics and Etiology of Community-acquired Pneumonia in US Children, 2015-2018

BACKGROUND

Pneumonia has a major impact on childhood health and health care costs. This study was designed to obtain contemporary information on the clinical characteristics and etiology of community-acquired pneumonia (CAP) in children from both inpatient and outpatient settings in the USA.

METHODS

We conducted a prospective, multicenter, observational study of CAP among previously healthy children 2 months to 18 years of age in 6 children's hospitals in Ohio from 2015 to 2018. For pathogen detection, nasopharyngeal swabs were collected from all subjects. Blood and pleural fluid cultures were available per standard of care.

RESULTS

We enrolled a convenience sample of 441 patients: 380 hospitalized and 61 outpatients. Tachypnea and radiologic findings of consolidation and pleural effusion were more frequent among inpatients than outpatients. A pathogen was detected in 64.6% of patients: viruses in 55.6%, atypical bacteria in 8.8% and pyogenic bacteria in 4.3%. Eighteen (4.1%) patients had both viruses and bacteria detected. Rhinovirus/enterovirus (RV; 18.6%) and respiratory syncytial virus (RSV; 16.8%) were the viruses most frequently detected, and Mycoplasma pneumoniae (8.2%) and Streptococcus pneumoniae (2.3%) were the most common bacteria. Except for S. pneumoniae, which was identified more frequently in inpatients, there were no significant differences between inpatients and outpatients in the proportions of children with specific pathogens detected.

CONCLUSIONS

Rhinovirus/enterovirus and RSV among viruses and M. pneumoniae and S. pneumoniae among bacteria were the most common pathogens detected in children with CAP. Tachypnea and chest radiographs with consolidation and/or pleural effusion were associated with hospitalization.

A prediction study of IL-18 and IFN-γ in glucocorticoid treatment response in infants and young children with severe Mycoplasma pneumoniae pneumonia

BACKGROUND

In infants and young children, the clinical decision to apply glucocorticoids to severe Mycoplasma pneumoniae pneumonia (SMPP) is more an empirical choice with reference to clinical symptoms, but the effect is not satisfying. We aimed to explore and identify early predictive indicators of ideal response to glucocorticoids treatment in SMPP in infants and young children.

METHODS

We retrospectively reviewed the data of 59 patients, which met the age range and diagnostic criteria, admitted to Department of Pediatrics, the Sixth People's Hospital Affiliated to Shanghai Jiaotong University, from January to December 2017. Patients were divided into a glucocorticoid treatment group and a normal treatment group according to whether glucocorticoid treatment was used, and the difference in therapeutic effectiveness was compared between two groups. The glucocorticoid treatment group was further subdivided into effective versus ineffective treatment groups dependent on the difference of glucocorticoid treatment effect in main clinical symptoms improvement. We obtained the test value of biomarkers by ELISA, and identified several specific indicators with significantly different expressions in the early stage by independent sample t-tests and calculated their cut-off values by ROC curve.

RESULTS

Thirty-one SMPP patients who received glucocorticoid treatment were divided into effective and ineffective treatment groups according to the clinical improvements shown on different days of glucocorticoid use. The expression of two markers, interleukin-18 (IL-18) and interferon-γ (IFN-γ), were significantly different in cases showing improvement in the early stage of SMPP (P<0.05), and the cut-off values for IL-18 (218.19 pg/mL, AUC =0.581, sensitivity =0.909, 1-specificity =0.786) and IFN-γ (11.24 pg/mL, AUC =0.566, sensitivity =0.905, 1-specificity =0.795) were identified.

CONCLUSIONS

The expressions of IL-18 and IFN-γ in the early stage of SMPP might suggest their predictive effect of early application of glucocorticoid for effective treatment of SMPP in infants and young children. Further study with larger sample size will be carried on in the future.

Incidence of lower respiratory tract infection and associated viruses in a birth cohort in the Philippines

Background

Lower respiratory tract infection (LRTI) is an important cause of morbidity and mortality in infants and young children. However, the etiological role of viruses and the timing of developing LRTI are not well defined.

Methods

We analyzed the data of a prospective cohort study in the Philippines as a birth cohort. We detected LRTI among children who visited healthcare facilities with respiratory symptom, and collected nasopharyngeal swabs for virus detection. We analyzed the incidence rates (IRs) and cumulative proportion of LRTI and severe LRTI by age group and each virus detected.

Results

A total of 350 LRTI episodes were observed from 473 child-years yielded from 419 children. The IRs of LRTI were 70.8, 70.7, and 80.8 per 100 child-years for 0–5, 6–11, and 12–23 months of age, respectively. By 12 months of age, 45% of children developed LRTI at least once. Rhinovirus and respiratory syncytial virus were the most frequently detected viruses in all age groups. However, the IRs of influenza virus were low especially at 0–5 months of age.

Conclusions

We identified various patterns of age-specific IRs of LRTI and severe LRTI for different viruses, which should be considered to establish more effective interventions including vaccinations.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-022-07289-3.

Mycoplasma pneumoniae Pleural Effusion in Adults

Parapneumonic effusions often complicate Mycoplasma pneumoniae (MP) pneumonia, contrary to the notion that they are a rare feature of MP infection. Increased research and evidence on MP parapneumonic effusions (MPPE) can help elucidate its clinical significance as one of the variable manifestations of MP infection. This article aims to summarize the existing literature about the clinical characteristics of MPPE in adults and discuss its diagnostic implications from the perspective of pleural fluid analysis. Approximately 20–25% of adult patients with MP pneumonia develop MPPE, and its frequency in children and adults seems to be similar. Although the pathogenesis of MPPE remains to be elucidated, MP-induced cell-mediated immune mechanisms might be partially associated with the development of MPPE. MPPE usually shows mononuclear leukocyte predominance with elevated adenosine deaminase (ADA) activity, similar to tuberculous pleural effusion (TPE). The degree of increase in pleural fluid ADA levels and serum inflammatory biomarkers may help differentiate between MPPE and TPE. During the acute phase, a single positive IgM and positive polymerase chain reaction results allow for a precise and reliable MP infection diagnosis. The mainstay of treatment is the selection of adequate anti-mycoplasma antibiotics with or without corticosteroid, based on the local epidemiologic data on macrolide resistance.

Mycoplasma Pneumoniae Infection and Persistent Wheezing in Young Children: A Retrospective Case-Control Study

BACKGROUND

To investigate the clinical characteristics of children with persistent wheezing (PW) with Mycoplasma pneumoniae (MP) DNA in bronchoalveolar lavage fluid (BALF).

METHODS

This retrospective case-control study included consecutive admitted children under 3 years of age who were diagnosed with PW and had MP DNA detected in BALF. Patients with mycoplasma pneumoniae pneumonia (MPP) and foreign-body aspiration (FBA) were enrolled as controls. The clinical characteristics of the groups were compared.

RESULTS

During the study period, there were 89 patients diagnosed with PW without structural anomalies of the conductive airways, and 30 of these patients (33.7%, 30/89) with MP DNA detected in the BALF were selected as the study group. We included 44 patients with MPP and 44 patients with FBA as controls. Patients with MPP were older and had a higher occurrence of fever and C-reactive protein (CRP) than patients with PW (all P < 0.001). The median MP DNA copy number in patients with MPP was higher than that of patients with PW (P = 0.004). The median level of MP IgG in patients with PW was lower than that of patients with MPP and higher than that of patients with FBA (all P < 0.001). MP DNA copy number positively correlated with age (r = 0.392, P = 0.001) and CRP (r = 0.235, P = 0.048).

CONCLUSIONS

Our study reveals that MP was highly detected in the BALF of PW patients. In addition, young patients with a low load of MP infection showed lower amounts of antibody, and a weak inflammatory response might be associated with PW.

Viral and Atypical Bacterial Detection in Young Nepalese Children Hospitalized with Severe Pneumonia

Respiratory viruses cause a substantial proportion of respiratory tract infections in children but are underrecognized as a cause of severe pneumonia hospitalization in low-income settings. We employed 22 real-time PCR assays and retrospectively reanalyzed 610 nasopharyngeal aspirate specimens from children aged 2 to 35 months with severe pneumonia (WHO definition) admitted to Kanti Childrens' Hospital in Kathmandu, Nepal, from January 2006 through June 2008. Previously, ≥1 of 7 viruses had been detected by multiplex reverse transcription-PCR in 30% (188/627) of cases. Reanalyzing the stored specimens, we detected ≥1 pathogens, including 18 respiratory viruses and 3 atypical bacteria, in 98.7% (602/610) of cases. Rhinovirus (RV) and respiratory syncytial virus (RSV) were the most common, detected in 318 (52.1%) and 299 (49%) cases, respectively, followed by adenovirus (AdV) (10.6%), human metapneumovirus (hMPV) (9.7%), parainfluenza virus type 3 (8.4%), and enterovirus (7.7%). The remaining pathogens were each detected in less than 5%. Mycoplasma pneumoniae was most common among the atypical bacteria (3.7%). Codetections were observed in 53.3% of cases. Single-virus detection was more common for hMPV (46%) and RSV (41%) than for RV (22%) and AdV (6%). The mean cycle threshold value for detection of each pathogen tended to be lower in single-pathogen detections than in codetections. This finding was significant for RSV, RV, and AdV. RSV outbreaks occurred at the end of the monsoon or during winter. An expanded diagnostic PCR panel substantially increased the detection of respiratory viruses in young Nepalese children hospitalized with severe pneumonia. IMPORTANCE Respiratory viruses are an important cause of respiratory tract infections in children but are underrecognized as a cause of pneumonia hospitalization in low-income settings. Previously, we detected at least one of seven respiratory viruses by PCR in 30% of young Nepalese children hospitalized with severe pneumonia over a period of 36 months. Using updated PCR assays detecting 21 different viruses and atypical bacteria, we reanalyzed 610 stored upper-respiratory specimens from these children. Respiratory viruses were detected in nearly all children hospitalized for pneumonia. RSV and rhinovirus were the predominant pathogens detected. Detection of two or more pathogens was observed in more than 50% of the pneumonia cases. Single-virus detection was more common for human metapneumovirus and RSV than for rhinovirus and adenovirus. The concentration of virus was higher (low cycle threshold [CT] value) for single detected pathogens, hinting at a high viral load as a marker of clinical significance.

Mycoplasma Pneumoniae Testing and Treatment Among Children With Community-Acquired Pneumonia

OBJECTIVES

To describe testing and treatment practices for Mycoplasma pneumoniae (Mp) among children hospitalized with community-acquired pneumonia (CAP).

METHODS

We conducted a retrospective cohort study using the Pediatric Health Information Systems database. We included children 3 months to 18 years old hospitalized with CAP between 2012 and 2018 and excluded children who were transferred from another hospital and those with complex chronic conditions. We examined the proportion of patients receiving Mp testing and macrolide therapy at the hospital level and trends in Mp testing and macrolide prescription over time. At the patient level, we examined differences in demographics, illness severity (eg, blood gas, chest tube placement), and outcomes (eg, ICU admission, length of stay, readmission) among patients with and without Mp testing.

RESULTS

Among 103 977 children hospitalized with CAP, 17.3% underwent Mp testing and 31.1% received macrolides. We found no correlation between Mp testing and macrolide treatment at the hospital level (R ² = 0.05; P = .11). Patients tested for Mp were more likely to have blood gas analysis (15.8% vs 12.8%; P < .1), chest tube placement (1.4% vs 0.8%; P < .1), and ICU admission (3.1% vs 1.4%; P < .1). Mp testing increased (from 15.8% to 18.6%; P < .001), and macrolide prescription decreased (from 40.9% to 20.6%; P < .001) between 2012 and 2018.

CONCLUSIONS

Nearly one-third of hospitalized children with CAP received macrolide antibiotics, although macrolide prescription decreased over time. Clinicians were more likely to perform Mp testing in children with severe illness, and Mp testing and macrolide treatment were not correlated at the hospital level.

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

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.

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.

Atypical case of mild encephalopathy/encephalitis with reversible splenial lesion of the corpus callosum (MERS) associated with Mycoplasma pneumoniae infection in a paediatric patient

Mild encephalopathy with reversible splenial lesion (MERS) is a disorder characterised by prodromal symptoms such as fever, cough, vomiting or diarrhoea, followed by mild encephalopathy 1-7 days later with a documented reversible corpus callosum splenial lesion. MERS is mostly reported in children in the region of East Asia. To the best of our knowledge, this is the first reported case of MERS associated with mycoplasma infection in a child in North America. A brief review of literature is also a part of this report.

Antigen-Presenting Cells in the Airways: Moderating Asymptomatic Bacterial Carriage

Bacterial respiratory tract infections (RTIs) are a major global health burden, and the role of antigen-presenting cells (APCs) in mounting an immune response to contain and clear invading pathogens is well-described. However, most encounters between a host and a bacterial pathogen do not result in symptomatic infection, but in asymptomatic carriage instead. The fact that a pathogen will cause infection in one individual, but not in another does not appear to be directly related to bacterial density, but rather depend on qualitative differences in the host response. Understanding the interactions between respiratory pathogens and airway APCs that result in asymptomatic carriage, will provide better insight into the factors that can skew this interaction towards infection. This review will discuss the currently available knowledge on airway APCs in the context of asymptomatic bacterial carriage along the entire respiratory tract. Furthermore, in order to interpret past and futures studies into this topic, we propose a standardized nomenclature of the different stages of carriage and infection, based on the pathogen’s position with regard to the epithelium and the amount of inflammation present.

The Role of the Respiratory Microbiome and Viral Presence in Lower Respiratory Tract Infection Severity in the First Five Years of Life

Lower respiratory tract infections (LRTIs) in children are common and, although often mild, a major cause of mortality and hospitalization. Recently, the respiratory microbiome has been associated with both susceptibility and severity of LRTI. In this current study, we combined respiratory microbiome, viral, and clinical data to find associations with the severity of LRTI. Nasopharyngeal aspirates of children aged one month to five years included in the STRAP study (Study to Reduce Antibiotic prescription in childhood Pneumonia), who presented at the emergency department (ED) with fever and cough or dyspnea, were sequenced with nanopore 16S-rRNA gene sequencing and subsequently analyzed with hierarchical clustering to identify respiratory microbiome profiles. Samples were also tested using a panel of 15 respiratory viruses and Mycoplasma pneumoniae, which were analyzed in two groups, according to their reported virulence. The primary outcome was hospitalization, as measure of disease severity. Nasopharyngeal samples were isolated from a total of 167 children. After quality filtering, microbiome results were available for 54 children and virology panels for 158 children. Six distinct genus-dominant microbiome profiles were identified, with Haemophilus-, Moraxella-, and Streptococcus-dominant profiles being the most prevalent. However, these profiles were not found to be significantly associated with hospitalization. At least one virus was detected in 139 (88%) children, of whom 32.4% had co-infections with multiple viruses. Viral co-infections were common for adenovirus, bocavirus, and enterovirus, and uncommon for human metapneumovirus (hMPV) and influenza A virus. The detection of enteroviruses was negatively associated with hospitalization. Virulence groups were not significantly associated with hospitalization. Our data underlines high detection rates and co-infection of viruses in children with respiratory symptoms and confirms the predominant presence of Haemophilus-, Streptococcus-, and Moraxella-dominant profiles in a symptomatic pediatric population at the ED. However, we could not assess significant associations between microbiome profiles and disease severity measures.

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.

Mycoplasma pneumoniae biofilms grown in vitro: traits associated with persistence and cytotoxicity

The atypical bacterial pathogen Mycoplasma pneumoniae is a leading etiological agent of community-acquired pneumonia in humans; infections are often recalcitrant, recurrent and resistant to antibiotic treatment. These characteristics suggest a mechanism that facilitates long-term colonization in hosts. In an in vitro setting, M. pneumoniae forms biofilms that are unusual in that motility plays no more than a very limited role in their formation and development. Given the unusual nature of M. pneumoniae biofilms, open questions remain concerning phenotypes associated with persistence, such as what properties might favour the bacteria while minimizing host damage. M. pneumoniae also produces several cytotoxic molecules including community-acquired respiratory distress syndrome (CARDS) toxin, H₂S and H₂O₂, but how it deploys these agents during growth is unknown. Whereas several biochemical techniques for biofilm disruption were ineffective, sonication was required for disruption of M. pneumoniae biofilms to generate individual cells for comparative studies, suggesting unusual physical properties likely related to the atypical cell envelope. Nonetheless, like for other bacteria, biofilms were less susceptible to antibiotic inhibition and complement killing than dispersed cells, with resistance increasing as the biofilms matured. CARDS toxin levels and enzymatic activities associated with H₂S and H₂O₂ production were highest during early biofilm formation and decreased over time, suggesting attenuation of virulence in connection with chronic infection. Collectively, these findings result in a model of how M. pneumoniae biofilms contribute to both the establishment and propagation of M. pneumoniae infections, and how both biofilm towers and individual cells participate in persistence and chronic disease.

Mycoplasma pneumoniae-associated mucositis

A 9-year-old boy presented to the emergency department of a paediatric hospital with non-painful lesions on his lips and inside his mouth, associated with lip swelling. On examination, his oral mucosa and lips showed numerous blisters with yellowish serofibrinous content and lip oedema. An eye examination revealed bilateral conjunctival injection. Genitalia was unaffected and no other skin lesions were found. He was on day 4 of clarithromycin prescribed for atypical pneumonia caused by Mycoplasma pneumoniae The patient was diagnosed with M. pneumoniae-associated mucositis and was started on topical treatment with fusidic acid and betamethasone, with gradual improvement of the oral lesions.

Seasonality in testing and positive respiratory bacterial infections in the Australian Capital Territory, 1997-2007

Background

Chlamydia pneumoniae (Cp) and Mycoplasma pneumoniae (Myco) bacteria are atypical pathogens that can cause pneumonia and exacerbate underlying conditions such as asthma and chronic obstructive pulmonary disease. In the Australian Capital Territory, there is limited information on how seasonal patterns for positive infections and testing may vary, a gap that has implications for control strategies.

Methods

We examined seasonal patterns of immunoassay results of patients from Canberra Hospital, Australia, who were tested for Cp and/or Myco. Pathology data, collected from August 1997 to March 2007 from 7,275 patients, were analysed with time series additive decomposition and time series regression.

Results

The proportion of positive Cp infections was highest in March and April (autumn) and lowest in June and August (winter). The proportion of positive Myco infections was highest in December and January (summer) and lowest in August (winter), even though testing for the pathogen peaked in winter with a low in summer. Models with a long-term trend and a variable for month were a better fit for the data than the null models for both infections.

Conclusion

We found differences in seasonal patterns of testing and in the proportion of positive infections. These findings suggest that preventative measures for common infections need to account for seasonal testing practices so as to build an accurate picture of temporal changes in these infections.

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.