Infection with and Carriage of Mycoplasma pneumoniae in Children

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.

Correlation between fat-soluble vitamin levels and inflammatory factors in paediatric community-acquired pneumonia: A prospective study

Community-acquired pneumonia (CAP) is a common respiratory disease in children. This prospective cohort study of 110 children with CAP and 100 healthy children investigated the relationship between the levels of vitamin A, D and E and inflammatory markers, such as tumour necrosis factor (TNF-a), interleukin-1 (IL-1), interleukin-10 (IL-10), neutrophils (NE) and C-reactive protein (CRP), in CAP. The haemoglobin, leukocyte concentration, NE, monocytes and CRP concentration in the CAP group showed significant differences (P < 0.05). The levels of vitamin A, D and E in the CAP group were lower than those in the control group, while the levels of TNF-a and IL-1 were higher than in the control group; the differences were statistically significant (P < 0.05). The IL-10 levels showed no significant differences (P > 0.05). Pearson analysis revealed that the vitamin A, D and E levels were all correlated with the TNF-a, IL-10 and CRP levels (P < 0.05). The vitamin A, D and E levels of the CAP children were lower than those of the healthy children. Thus, the content of fat-soluble vitamins is correlated with the secretion of TNF-a and IL-10. The research provides a new direction for the prevention, diagnosis and treatment of CAP.

Global, regional, and national incidence and mortality burden of non-COVID-19 lower respiratory infections and aetiologies, 1990-2021: a systematic analysis from the Global Burden of Disease Study 2021

BACKGROUND

Lower respiratory infections (LRIs) are a major global contributor to morbidity and mortality. In 2020-21, non-pharmaceutical interventions associated with the COVID-19 pandemic reduced not only the transmission of SARS-CoV-2, but also the transmission of other LRI pathogens. Tracking LRI incidence and mortality, as well as the pathogens responsible, can guide health-system responses and funding priorities to reduce future burden. We present estimates from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 of the burden of non-COVID-19 LRIs and corresponding aetiologies from 1990 to 2021, inclusive of pandemic effects on the incidence and mortality of select respiratory viruses, globally, regionally, and for 204 countries and territories.

METHODS

We estimated mortality, incidence, and aetiology attribution for LRI, defined by the GBD as pneumonia or bronchiolitis, not inclusive of COVID-19. We analysed 26 259 site-years of mortality data using the Cause of Death Ensemble model to estimate LRI mortality rates. We analysed all available age-specific and sex-specific data sources, including published literature identified by a systematic review, as well as household surveys, hospital admissions, health insurance claims, and LRI mortality estimates, to generate internally consistent estimates of incidence and prevalence using DisMod-MR 2.1. For aetiology estimation, we analysed multiple causes of death, vital registration, hospital discharge, microbial laboratory, and literature data using a network analysis model to produce the proportion of LRI deaths and episodes attributable to the following pathogens: Acinetobacter baumannii, Chlamydia spp, Enterobacter spp, Escherichia coli, fungi, group B streptococcus, Haemophilus influenzae, influenza viruses, Klebsiella pneumoniae, Legionella spp, Mycoplasma spp, polymicrobial infections, Pseudomonas aeruginosa, respiratory syncytial virus (RSV), Staphylococcus aureus, Streptococcus pneumoniae, and other viruses (ie, the aggregate of all viruses studied except influenza and RSV), as well as a residual category of other bacterial pathogens.

FINDINGS

Globally, in 2021, we estimated 344 million (95% uncertainty interval [UI] 325-364) incident episodes of LRI, or 4350 episodes (4120-4610) per 100 000 population, and 2·18 million deaths (1·98-2·36), or 27·7 deaths (25·1-29·9) per 100 000. 502 000 deaths (406 000-611 000) were in children younger than 5 years, among which 254 000 deaths (197 000-320 000) occurred in countries with a low Socio-demographic Index. Of the 18 modelled pathogen categories in 2021, S pneumoniae was responsible for the highest proportions of LRI episodes and deaths, with an estimated 97·9 million (92·1-104·0) episodes and 505 000 deaths (454 000-555 000) globally. The pathogens responsible for the second and third highest episode counts globally were other viral aetiologies (46·4 million [43·6-49·3] episodes) and Mycoplasma spp (25·3 million [23·5-27·2]), while those responsible for the second and third highest death counts were S aureus (424 000 [380 000-459 000]) and K pneumoniae (176 000 [158 000-194 000]). From 1990 to 2019, the global all-age non-COVID-19 LRI mortality rate declined by 41·7% (35·9-46·9), from 56·5 deaths (51·3-61·9) to 32·9 deaths (29·9-35·4) per 100 000. From 2019 to 2021, during the COVID-19 pandemic and implementation of associated non-pharmaceutical interventions, we estimated a 16·0% (13·1-18·6) decline in the global all-age non-COVID-19 LRI mortality rate, largely accounted for by a 71·8% (63·8-78·9) decline in the number of influenza deaths and a 66·7% (56·6-75·3) decline in the number of RSV deaths.

INTERPRETATION

Substantial progress has been made in reducing LRI mortality, but the burden remains high, especially in low-income and middle-income countries. During the COVID-19 pandemic, with its associated non-pharmaceutical interventions, global incident LRI cases and mortality attributable to influenza and RSV declined substantially. Expanding access to health-care services and vaccines, including S pneumoniae, H influenzae type B, and novel RSV vaccines, along with new low-cost interventions against S aureus, could mitigate the LRI burden and prevent transmission of LRI-causing pathogens.

FUNDING

Bill & Melinda Gates Foundation, Wellcome Trust, and Department of Health and Social Care (UK).

Characteristics of the Mycoplasma pneumoniae Epidemic from 2019 to 2020 in Korea: Macrolide Resistance and Co-Infection Trends

Mycoplasma pneumoniae, a major etiological agent of community-acquired pneumonia, exhibits distinct cyclic epidemic patterns recurring every three to five years. Several cases of co-infection with severe acute respiratory syndrome coronavirus 2 have been reported globally, resulting in unfavorable clinical manifestations. This study investigated the epidemiological features of the recent M. pneumoniae outbreak (May 2019-April 2020) using retrospective data from the last five years. Molecular test data for macrolide resistance and co-infection were obtained from the Seegene Medical Foundation. National medical expenditure and hospitalization rates were analyzed using data from The Health Insurance Review and Assessment Service of Korea. The macrolide resistance rate was 69.67%, peaking at 71.30% during the epidemic period, which was considerably higher than the 60.89% rate during non-epidemic periods. The co-infection rate with other respiratory pathogens was 88.49%; macrolide-resistant M. pneumoniae strains showed a 2.33% higher co-infection rate than the susceptible strains. The epidemic period had 15.43% higher hospitalization and 78.27% higher medical budget expenditure per patient than non-epidemic periods. The increased rates of macrolide resistance and co-infection observed in macrolide-resistant M. pneumoniae during the epidemic period highlight the importance of monitoring future outbreaks, especially considering macrolide resistance and the risk of co-infection with other pathogens.

Optimization strategy for the early timing of bronchoalveolar lavage treatment for children with severe mycoplasma pneumoniae pneumonia

BACKGROUND

Early evaluation of severe mycoplasma pneumoniae pneumonia (SMPP) and the prompt utilization of fiberoptic bronchoscopic manipulation can effectively alleviate complications and restrict the progression of sequelae. This study aim to establish a nomogram forecasting model for SMPP in children and explore an optimal early therapeutic bronchoalveolar lavage (TBAL) treatment strategy.

METHODS

This retrospective study included children with mycoplasma pneumoniae pneumonia (MPP) from January 2019 to December 2021. Multivariate logistic regression analysis was used to screen independent risk factors for SMPP and establish a nomogram model. The bootstrap method was employed and a receiver operator characteristic (ROC) curve was drawn to evaluate the accuracy and robustness of the model. Kaplan-Meier analysis was used to assess the effect of lavage and hospitalization times.

RESULTS

A total of 244 cases were enrolled in the study, among whom 68 with SMPP and 176 with non-SMPP (NSMPP). A prediction model with five independent risk factors: left upper lobe computed tomography (CT) score, sequential organ failure assessment (SOFA) score, acute physiology and chronic health assessment (APACHE) II score, bronchitis score (BS), and c-reactive protein (CRP) was established based on the multivariate logistic regression analysis. The ROC curve of the prediction model showed the area under ROC curve (AUC) was 0.985 (95% confidence interval (CI) 0.972-0.997). The Hosmer-Lemeshow goodness-of-fit test results showed that the nomogram model predicted the risk of SMPP well (χ2 = 2.127, P = 0.977). The log-rank result suggested that an early BAL treatment could shorten MPP hospitalization time (P = 0.0057).

CONCLUSION

This nomogram model, based on the left upper lobe CT score, SOFA score, APACHE II score, BS, and CRP level, represents a valuable tool to predict the risk of SMPP in children and optimize the timing of TBAL.

Genotyping of Mycoplasma pneumoniae strains isolated in Japan during 2019 and 2020: spread of p1 gene type 2c and 2j variant strains

We characterized 118 Mycoplasma pneumoniae strains isolated from three areas of Japan (Saitama, Kanagawa, and Osaka) during the period of 2019 and 2020. Genotyping of the p1 gene in these strains revealed that 29 of them were type 1 lineage (29/118, 24.6%), while 89 were type 2 lineage (89/118, 75.4%), thereby indicating that type 2 lineage was dominant in this period. The most prevalent variant of type 2 lineage was type 2c (57/89, 64%), while the second-most was type 2j, a novel variant identified in this study (30/89, 33.7%). Type 2j p1 is similar to type 2 g p1, but cannot be distinguished from reference type 2 (classical type 2) using the standard polymerase chain reaction-restriction fragment length polymorphism analysis (PCR-RFLP) with HaeIII digestion. Thus, we used MboI digestion in the PCR-RFLP analysis and re-examined the data from previous genotyping studies as well. This revealed that most strains reported as classical type 2 after 2010 in our studies were actually type 2j. The revised genotyping data showed that the type 2c and 2j strains have been spreading in recent years and were the most prevalent variants in Japan during the time-period of 2019 and 2020. We also analyzed the macrolide-resistance (MR) mutations in the 118 strains. MR mutations in the 23S rRNA gene were detected in 29 of these strains (29/118, 24.6%). The MR rate of type 1 lineage (14/29, 48.3%) was still higher than that of type 2 lineage (15/89, 16.9%); however, the MR rate of type 1 lineage was lower than that found in previous reports published in the 2010s, while that of type 2 lineage strains was slightly higher. Thus, there is a need for continuous surveillance of the p1 genotype and MR rate of M. pneumoniae clinical strains, to better understand the epidemiology and variant evolution of this pathogen, although M. pneumoniae pneumonia cases have decreased significantly since the COVID-19 pandemic.

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.

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.

Amino-modified silica membrane capable of DNA extraction and enrichment for facilitated isothermal amplification detection of Mycoplasma pneumoniae

Herein, we developed a facile integrated Mycoplasma pneumoniae diagnosis platform by combining amino-modified silica membrane (AMSM)-based nucleic acids fast extraction and enrichment with colorimetric isothermal amplification detection. AMSM demonstrates a strong ability to capture and enrich nucleic acids in complicated biological matrices, and the purified AMSM/nucleic acids composite could be directly used to perform isothermal amplification including denaturation bubble-mediated strand exchange amplification (SEA) and loop-mediated isothermal amplification (LAMP) reactions. Through comparing clinical specimens, excellent performance of AMSM-based SEA assay with 93.33% sensitivity and 100% specificity relative to real-time PCR was observed, and for AMSM-based LAMP was 96.67% and 100%, respectively. The diagnostic procedure could be completed within 55 min, and the colorimetric-based visual result further alleviates the use of sophisticated equipment. The proposed approach possesses great potential as a simple and time-saving alternative for point-of-care testing (POCT) of M. pneumoniae in resource-limited regions.

Risk of Dental Discoloration and Enamel Dysplasia in Children Exposed to Tetracycline and Its Derivatives

PURPOSE

To examine the risk of dental abnormalities after exposure to tetracycline and its derivatives (TCs) in Korean children.

MATERIALS AND METHODS

Children aged 0-17 years with a claim for prescriptions of TCs between 2002 and 2015 were identified from the Sample Research Database 2.0 of the National Health Insurance Service. Children not exposed to TCs were selected as the control group by matching sex and age (1:4). Cumulative incidence rate and relative risk of dental abnormalities after TCs exposure were investigated.

RESULTS

The 10-year cumulative incidence rate in the 0-12 years group was 3.1% [95% confidence interval (CI), 2.3-3.9]. The 10-year cumulative incidence rates were 7.0%, 1.9%, and 1.6% in the 0-7, 8-12, and 13-17 years age groups (95% CI: 4.7-9.3, 1.2-2.6, and 1.3-1.9, respectively). There was no significant difference in the risk of dental abnormalities according to TC exposure among the age groups of 0-7 years [adjusted hazard ratio (aHR)=1.0], 8-12 years (aHR=1.1), and 13-17 years (aHR=1.2).

CONCLUSION

Short-term exposure to TCs does not appear to increase the risk of dental abnormalities in children aged 0-7 and 0-12 years. Restrictions on the use of TCs in children aged 8-12 years, in some countries, may warrant consideration.

Clinical role of M. pneumoniae typing antibody detected by chemiluminescent immunoassay in the diagnosis of Mycoplasma pneumoniae pneumonia in children

OBJECTIVE

The levels of serum M. pneumoniae typing antibodies in children with community-acquired pneumonia (CAP) were detected by chemiluminescent immunoassay (CLIA) to explore the clinical role of M. pneumoniae typing antibody (MP-IgM, MP-IgG) in M. pneumoniae pneumonia.

METHODS

A total of 387 Child patients with CAP diagnosed at the Pediatric outpatient department of Zengcheng Branch, Nanfang Hospital, Southern Medical University, were enrolled between January 2020 to December 2021 and divided into M. pneumoniae pneumonia (MPP) group (n = 210) and non-M. pneumoniae pneumonia (NMPP) group (n = 177). Firstly, Clinical data, full blood count (WBC, NEU%, LYM%, MONO%, EOS%, BASO%, RBC, HGB, PLT) and biochemical tests (AST, LDH, ɑ-HBDH, CK, CKMB, CRP, PCT, IL-6) as well as laboratory diagnostic tests (MP-IgM, MP-IgG) were compared between the two groups. Secondly, we assessed the correlation between the average level of M. pneumoniae typing antibody detected by CLIA and the titer of anti-M. pneumoniae antibody (MP-Ab) tested by passive agglutination (PA) method. Thirdly, receiver operating characteristic (ROC) curve for the MP-IgM and MP-IgG was examined to evaluate the value of diagnosing M. pneumoniae pneumonia. Finally, we follow-up 120 cases of MPP group and analysis medication results.

RESULTS

(1) Mean age, runny nose, expectoration, LYM%, NEU%, HGB, AST, MP-IgM and MP-IgG were statistically significant in the MPP group and NMPP group (all P < 0.05). (2) Correlation analysis showed that MP-IgM average level was linearly associated with MP-Ab titer (R² = 0.84) and MP-IgG average level was exponentially correlated with MP-Ab titer under 1:640 (R² = 0.96). (3) The ROC curve of MP-IgM and MP-IgG were significantly different (both P < 0.001). A serum MP-IgM level above 1 S/CO and MP-IgG level above 14.15 AU/mL were significant predictors for M. pneumoniae pneumonia: area under the curve (AUC) of 0.810, 0.815; standard error (SE) of 0.021, 0.022; 95 % confidence interval (CI) of 0.768-0.852, 0.773-0.858; the diagnostic sensitivity of 74.3 %, 62.1 %; and specificity of 72.9 %, 87.0 %; respectively. (4) Of the 120 children with M. pneumoniae pneumonia followed up, 79 (65.8 %) cases took azithromycin and 68 (86.1 %) cases were recovered.

CONCLUSIONS

A series of our studies shown that, CLIA, speedy and automated clinical examination method, has higher specificity and sensitivity for the quantitative detection of MP-IgM and MP-IgG, playing an important role of early diagnosis as well as prompt intervention to reduces macrolide-resistant strains and sequelae of children with M. pneumoniae pneumonia.

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 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.

Mycoplasmas as Host Pantropic and Specific Pathogens: Clinical Implications, Gene Transfer, Virulence Factors, and Future Perspectives

Mycoplasmas as economically important and pantropic pathogens can cause similar clinical diseases in different hosts by eluding host defense and establishing their niches despite their limited metabolic capacities. Besides, enormous undiscovered virulence has a fundamental role in the pathogenesis of pathogenic mycoplasmas. On the other hand, they are host-specific pathogens with some highly pathogenic members that can colonize a vast number of habitats. Reshuffling mycoplasmas genetic information and evolving rapidly is a way to avoid their host's immune system. However, currently, only a few control measures exist against some mycoplasmosis which are far from satisfaction. This review aimed to provide an updated insight into the state of mycoplasmas as pathogens by summarizing and analyzing the comprehensive progress, current challenge, and future perspectives of mycoplasmas. It covers clinical implications of mycoplasmas in humans and domestic and wild animals, virulence-related factors, the process of gene transfer and its crucial prospects, the current application and future perspectives of nanotechnology for diagnosing and curing mycoplasmosis, Mycoplasma vaccination, and protective immunity. Several questions remain unanswered and are recommended to pay close attention to. The findings would be helpful to develop new strategies for basic and applied research on mycoplasmas and facilitate the control of mycoplasmosis for humans and various species of animals.

Laboratory analysis of positive rate of Mycoplasma pneumoniae antibody among 53,273 children with respiratory tract infections in Xi'an from 2017 to 2020

BACKGROUND

Mycoplasma pneumoniae (Mp) is an important pathogen that causes respiratory tract infections in children. Data on epidemiology of paediatric Mp infection in China are little known. The aim of this study was to investigate the infection of children with respiratory tract infection in Xi'an from 2017 to 2020, and to explore the epidemiological features of paediatric Mp infection in Northwest China during the past 4 years.

METHODS

A total of 53,273 paediatric patients diagnosed with respiratory tract infection as the first diagnosis were enrolled. Mp antibody was detected using passive agglutination method. Statistical analysis and epidemiological investigation were carried out on the test results according to different years, seasons, ages and genders. The differences among rates were analyzed by the χ² test. The trends among the rates were analyzed by the Poisson regression.

RESULTS

A total of 14,375 Mp antibody positive patients were detected, with a total positive rate of 26.98%. The rate of Mp infection in 2017 was significantly higher than other years (χ²=431.700; P=0.000), and the rate showed a downward trend year by year [incidence rate ratios (IRR) =0.906; 95% CI: 0.892-0.921; P=0.000]. The rate of Mp infection increased gradually in the order of spring, summer, autumn and winter (IRR =1.078; 95% CI: 1.060-1.097; P=0.000), and peaked in winter (29.08%). As age increased, the positive rate of Mp infection also gradually increased (IRR =1.138; 95% CI: 1.134-1.143; P=0.000). The peak age of Mp infection was between 6 and 12 years, accounting for 51.71%, significantly more compared with other age groups (χ²=4203.000, P=0.000). Female children had significantly higher positive rates than male children (χ²=527.000; P=0.000).

CONCLUSIONS

Mp infection mainly occurs related to year, season, age and gender. Understanding the epidemiological characteristics of paediatric Mp infection can contribute to timely treatment and diagnosis, and may improve the prognosis of children with Mp infection.

A systematic review of the clinical features of pneumonia in children aged 5-9 years: Implications for guidelines and research

Background

Childhood pneumonia presents a large global burden, though most data and guidelines focus on children less than 5 years old. Less information is available about the clinical presentation of pneumonia in children 5-9 years of age. Appropriate diagnostic and treatment algorithms may differ from those applied to younger children. This systematic literature review aimed to identify clinical features of pneumonia in children aged 5-9 years, with a focus on delineation from other age groups and comparison with existing WHO guidance for pneumonia in children less than 5 years old.

Methods

We searched MEDLINE, EMBASE and PubMed databases for publications that described clinical features of pneumonia in children 5-9 years old, from any country with no date restriction in English. The quality of included studies was evaluated using a modified Effective Public Health Project Practice (EPHPP) tool. Data relating to research context, study type, clinical features of pneumonia and comparisons with children less than 5 years old were extracted. For each clinical feature of pneumonia, we described mean percentage (95% confidence interval) of participants with this finding in terms of aetiology (all cause vs Mycoplasma pneumoniae), and method of diagnosis (radiological vs clinical).

Results

We included 15 publications, eight addressing all-cause pneumonia and seven addressing Mycoplasma pneumoniae. Cough and fever were common in children aged 5-9 years with pneumonia. Tachypnoea was documented in around half of patients. Dyspnoea/difficulty breathing and chest indrawing were present in approximately half of all-cause pneumonia cases, with no data on indrawing in the outpatient setting. Chest and abdominal pain were documented in around one third of cases of all-cause pneumonia, based on limited numbers. In addition to markers of pneumonia severity used in children <5 years, pallor has been identified as being associated with poorer outcomes alongside comorbidities and nutritional status.

Conclusions

Quality research exploring clinical features of pneumonia, treatment and outcomes in children aged 5-9 years using consistent inclusion criteria, definitions of features and age ranges are urgently needed to better inform practice and guidelines. Based on limited data fever and cough are common in this age group, but tachypnoea cannot be relied on for diagnosis. While waiting for better evidence, broader attention to features such as chest and abdominal pain, the role of chest radiographs for diagnosis in the absence of symptoms such as tachypnoea, and risk factors which may influence patient disposition (chest indrawing, pallor, nutritional status) warrant consideration by clinicians.

Protocol registration

PROSPERO: CRD42020213837.

Epidemiological Study on Mycoplasma pneumoniae and Chlamydia pneumoniae Infection of Hospitalized Children in a Single Center During the COVID-19 Pandemic

Background

Since the outbreak of COVID-19, a series of preventive and control measures in China have been used to effectively curb the spread of COVID-19. This study aimed to analyze the epidemiological characteristics of Mycoplasma pneumoniae (MP) and Chlamydia pneumoniae (CP) in hospitalized children with acute respiratory tract infection during the COVID-19 pandemic.

Methods

MP IgM antibody and CP IgM antibody were detected in all hospitalized children due to acute respiratory tract infection in the Children’s Hospital Affiliated to Zhejiang University from January 2019 to December 2020. These data were compared between 2019 and 2020 based on age and month.

Results

The overall detection rate of MP and CP in 2020 was significantly lower than that in 2019 (MP: 21.5% vs 32.9%, P<0.001; CP: 0.3% vs 0.9%, P<0.001). This study found a 4-fold reduction in the number of children positive for MP and a 7.5-fold reduction in the number of children positive for CP from 2019 to 2020. The positive cases were concentrated in children aged >1 year old. In 2019, the positive rate of MP was detected more commonly in children 3 years of age or older than in younger children. In 2020, the higher positive rate of MP reached a peak in the 3- to 6-year age group (35.3%). CP was detected predominantly in children aged 6 years older in 2019 and 2020, with positive rates of 4.8% and 2.6%, respectively. Meanwhile, the positive rates of MP in 2019 were detected more commonly in July, August and September, with 47.2%, 46.7% and 46.3%, respectively. Nevertheless, the positive rates of MP from February to December 2020 apparently decreased compared to those in 2019. The positive rates of CP were evenly distributed throughout the year, with 0.5%-1.6% in 2019 and 0.0%-2.1% in 2020.

Conclusions

A series of preventive and control measures for SARS-CoV-2 during the COVID-19 pandemic can not only contain the spread of SARS-CoV-2 but also sharply improve the infection of other atypical pathogens, including MP and CP.

Neutrophil-Mediated Lung Injury Both via TLR2-Dependent Production of IL-1α and IL-12 p40, and TLR2-Independent CARDS Toxin after Mycoplasma pneumoniae Infection in Mice

Mycoplasma pneumoniae (Mp) residing extracellularly in the respiratory tract is the primary cause of bacterial community-acquired pneumonia in humans. However, the detailed pathological mechanism of Mp infection, especially inflammation in the lung, remains unclear. This study examined the role of the neutrophils in the inflammation of Mp-induced pneumonia in mice and the mechanism of neutrophil infiltration into the lungs in the Mp-induced pneumonia. We observed massive infiltration of neutrophils in the bronchoalveolar lavage fluid (BALF) and lung injury after the Mp challenge. The neutrophils were shown to contribute to lung injury in Mp pneumonia but were not involved in eliminating Mp, suggesting that neutrophils are detrimental to the host in Mp pneumonia. Mp also induced the production of inflammatory cytokines and chemokines in the BALF in a toll-like receptor 2 (TLR2)-dependent manner. Particularly, both interleukin (IL)-1α and IL-12 p40 played a crucial role in neutrophil infiltration into the BALF in a coordinated manner. Both IL-1α and IL-12 p40 were released from the alveolar macrophages depending on the TLR2 and reactive oxygen species. In addition, the community-acquired respiratory distress syndrome (CARDS) toxin from Mp were found to induce neutrophil infiltration into BALF in a TLR2-independent and IL-1α-dependent manner. Collectively, the TLR2-dependent production of both IL-1α and IL-12 p40, and CARDS toxin have been elucidated to play an important role in neutrophil infiltration into the lungs subsequently leading to the lung injury upon Mp infection in mice. These data will aid in the development of therapeutics and vaccines for Mp pneumonia.

IMPORTANCE Although Mp-induced pneumonia is usually a self-limiting disease, refractory life-threatening pneumonia is often induced. In addition, the development of alternative therapeutic strategies for Mp is expected because of the emergence of antibiotic-resistant Mp. However, the lack of knowledge regarding the pathogenesis of Mp-induced pneumonia, especially inflammation upon the Mp infection, makes it tedious to design novel therapeutics and vaccines. For example, although neutrophil infiltration is widely recognized as one of the characteristics of Mp-induced pneumonia, the precise role of neutrophils in the aggravation of Mp pneumonia remains unclear. This study showed that the infiltration of neutrophils in the lungs is detrimental to the host in Mp-induced pneumonia in mice. Furthermore, the TLR2-dependent IL-1α and IL-12 p40 production, and CARDS toxin play important roles in neutrophil infiltration into the lung, following lung injury. Our findings apply to the rational design of novel therapeutics and vaccines against Mp.

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.

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

Macrolides (alone or in combination) should be used as first-line empirical therapy of community-acquired pneumonia in children: myth or maxim?

Macrolides should not be used as first-line therapy for community-acquired pneumonia in children as no clinical benefit is shown and widespread use is associated with an emerging increase in macrolide resistance amongst S. pneumoniae and M. pneumoniae https://bit.ly/3yQuedF.

Macrolide-Resistant Mycoplasma pneumoniae Infections in Pediatric Community-Acquired Pneumonia

A high prevalence rate of macrolide-resistant Mycoplasma pneumoniae (MRMP) has been reported in Asia. We performed a systematic review and meta-analysis to investigate the effect of macrolide resistance on the manifestations and clinical judgment during M. pneumoniae infections. We found no difference in clinical severity between MRMP and macrolide-sensitive Mycoplasma pneumoniae (MSMP) infections. However, in the pooled data, patients infected with MRMP had a longer febrile period (1.71 days), length of hospital stay (1.61 day), antibiotic drug courses (2.93 days), and defervescence time after macrolide treatment (2.04 days) compared with patients infected with MSMP. The risk of fever lasting for >48 hours after macrolide treatment was also significantly increased (OR 21.24), and an increased proportion of patients was changed to second-line treatment (OR 4.42). Our findings indicate diagnostic and therapeutic challenges after the emergence of MRMP. More precise diagnostic tools and clearly defined treatment should be appraised in the future.

Mycoplasma pneumoniae infection and risk of childhood asthma: A systematic review and meta-analysis

The etiology of childhood asthma is multifactorial, atypical bacterial pathogens, including Mycoplasma pneumoniae, have been proposed as possible risk factors or contributors. This review aims to assess the possible association between M. pneumoniae infection and childhood asthma. We searched major international literature databases (up to January 10, 2021) to identify relevant studies. We used a random-effects meta-analysis (REM) model to generate the pooled odds ratio (OR) and 95% confidence intervals (CIs). Several subgroups analyses were performed concerning the IgG, IgM, and DNA detection of M. pneumoniae infection. We included 22 eligible studies; these studies involved a total of 5064 children. We found that there was a statistically significant association between M. pneumoniae infection, as determined by IgM serology (OR, 3.13; 95% CI, 1.78-5.48), and DNA detection (OR, 1.57; 95% CI, 1.25-1.97) with increased risk of any type of childhood asthma. Moreover, children with acute asthma had significantly higher seropositivity for anti- M. pneumoniae IgM antibodies (OR, 4.43; 95% CI, 2.80-7.02) than children with stable asthma. Although our findings indicate a positive association between M. pneumoniae infection and childhood asthma, well-designed and -controlled studies are need in the future to rigorously test this association and identify the underlying mechanisms.

Analysis of mycoplasma pneumoniae infection among children with respiratory tract infections in hospital in Chengdu from 2014 to 2020

BACKGROUND

Respiratory tract infection (RTIs) is one of common diseases among the children. In recent years, the incidence of mycoplasma pneumoniae (M. pneumoniae) infection rate has been increasing, which cause respiratory tract infection. This study sought to analyze the epidemiological characteristics of M. pneumoniae hospitalized children with RTIs to provide a theoretical basis for clinical diagnosis and treatments in Chengdu, China.

METHODS

The data of 22,882 cases of children who had been hospitalized for RTIs were collected. M. pneumoniae immunoglobulin M (IgM) antibody was detected using the indirect immunofluorescence method and passive agglutination method. The demographic features of patients, clinical diagnoses and laboratory data were also analyzed.

RESULTS

A total of 4,213 children tested positive for M. pneumoniae. The total positive rate was 18.41% (18.30% for males and 22.72% for females). Female children had statistically significant higher positive rates than male children (χ²=198.078, P<0.01). The positive rates of M. pneumoniae differed significantly among children of different ages (F=162.7532, P<0.01). The incidence rate of M. pneumoniae in 2017 and 2019 was significantly higher than the average (F=538.95, P<0.01). There were higher M. pneumoniae positive rates from April to May, and September to October (P<0.05) in 2016, 2017, 2018, and 2019. There was no correlation between M. pneumoniae infection and temperature and humidity (P>0.05). There was negative correlation with PM_2.5 (particulate matter in the air <2.5 µm) (R=-0.293, P<0.01) and PM₁₀ (particulate matter in the air <10 µm). (R=-0.285, P<0.01). There were significant differences in the constituent ratios of cases of M. pneumoniae infection between in 2020 and other years (F=159.35, P<0.01). Bronchopneumonia accounted for the highest proportion of cases, followed by acute bronchitis and the exacerbation of asthma in 2020.

CONCLUSIONS

The epidemiological distribution of M. pneumoniae in children with RTIs in Chengdu was found to be related to gender, age, year and month; however, no relationship was found to temperature and humidity. There was a higher M. pneumoniae positive rate in children with bronchial pneumonia and asthma in cases. The prevention measures used to control Coronavirus Disease 2019 (COVID-19) also effectively controlled the M. pneumoniae infection rate.

Expression of Serum miR-155 in Children with Mycoplasma pneumoniae Pneumonia and Its Role in Immunity to Mycoplasma pneumoniae

Objective

To investigate the expression of serum miR-155 in children with Mycoplasma pneumoniae pneumonia (MPP).

Methods

A total of 100 children at our hospital with pneumonia caused by Mycoplasma pneumoniae infection were enrolled as a study group, including 45 cases in the acute phase (acute phase group) and 55 in the recovery phase (recovery phase group). An additional 30 healthy children were enrolled during the same period as the control group. The expression levels of miR-155, tumor necrosis factor-α (TNF-α), interleukin-8 (IL-8), IL-10, IL-13, immunoglobulin (Ig) G, IgA, complements (C3 and CH50), and T lymphocyte subsets (CD₃⁺, CD₄⁺, CD₈⁺, and CD₄⁺/CD₈⁺) were determined. Multivariate logistic regression analysis was performed to identify risk factors affecting MPP in children.

Results

miR-155, IL-10, IgG, IgA, CD₃⁺, CD₄⁺, and CD₄⁺/CD₈⁺ were poorly expressed in children with MPP, and their expression in the acute phase group was significantly lower than that in the recovery phase group. TNF-α, IL-13, C3, and CH50 were highly expressed in the children, and their expression was significantly higher in the acute  phase group than in the recovery phase group. In the acute phase group, the expression of IL-8 was significantly higher than that in the control and recovery phase groups but without any significant differences between the recovery phase and control groups. Age, season, low complement state, epidemiological contact history, and antibiotic use time were independent risk factors affecting MPP in children.

Conclusion

Serum miR-155 is poorly expressed in children with MPP, and it can regulate inflammatory disorders and immune responses.

Characteristics and Outcome of Severe Mycoplasma pneumoniae Pneumonia Admitted to PICU in Shanghai: A Retrospective Cohort Study

Objectives:

We aimed to describe the characteristics and outcome in children with severe Mycoplasma pneumoniae pneumonia in a Chinese PICU.

Design:

A retrospective observational study from 2017 to 2019.

Setting:

A 36-bed university tertiary PICU at Shanghai Children’s Hospital.

Patients:

Patients admitted to a tertiary PICU 29 days to 18 years old screened for laboratory-confirmed severe M. pneumoniae pneumonia.

Interventions:

None.

Measurements and Main Results:

Descriptive analysis of baseline characteristics for patients included hospital mortality, organ dysfunctions, use of mechanical ventilation, continuous renal replacement therapy, and/or extracorporeal membrane oxygenation. A total of 817 children with severe pneumonia were admitted to PICU, and 203 of 817 cases (24.8%) with severe M. pneumoniae pneumonia were included in this study. The median age was 41 months (interquartile range, 20–67 mo), of which 77.3% (157/203) were younger than 6 years old. Among 163 patients with the test for macrolide resistance, 90.2% cases (147/163) were macrolide-resistant M. pneumoniae. Severe M. pneumoniae pneumonia-associated organ dysfunction included acute respiratory failure (203 cases, 100%), followed by cardiovascular disorder (79/203, 38.9%), gastrointestinal dysfunction (24/203, 11.8%). The main complications were pleural effusion (79/203, 38.9%), capillary leak syndrome (58/203, 28.6%), and plastic bronchitis (20/203, 9.9%). All patients needed respiratory support, including 64.5% patients (131/203) who received mechanical ventilation and 35.5% patients (72/203) who received high-flow nasal oxygen. Twenty-five patients (12.3%) treated with continuous renal replacement therapy and nine cases (4.4%) received extracorporeal membrane oxygenation. The case fatality rate was 3.9% (8/203). Furthermore, cardiovascular dysfunction, liver injury, or multiple organ dysfunction syndrome were associated with longer mechanical ventilation duration, delayed PICU discharge, and high hospital mortality. Coinfection was a risk factor of delayed PICU discharge.

Conclusions:

Children with severe M. pneumoniae pneumonia mainly occur under the age of 6 years, showing a high proportion of extrapulmonary organ dysfunction and macrolide resistances. Extrapulmonary organ dysfunction and coinfection are associated with worse outcomes. The overall mortality is relatively low after treated with appreciate antibiotics, respiratory support, and extracorporeal life support.

Comparison of different detection methods for Mycoplasma pneumoniae infection in children with community-acquired pneumonia

BACKGROUND

Due to the lack of a sensitive, specific and rapid detection method, aetiological diagnosis of pneumonia caused by Mycoplasma pneumoniae (M. pneumoniae, MP) is a constantly challenging issue. This retrospective study aimed to compare the diagnostic methods for Mycoplasma pneumoniae in children and evaluate their values.

METHODS

From November 2018 to June 2019, 830 children with community-acquired pneumonia were selected from the Department of Respiratory Medicine, Shanghai Children's Medical Center. On the first day of hospitalization, sputum, throat swab and venous blood samples were collected to analyse MP-IgM (particle agglutination, PA), MP-IgM (immune colloidal gold technique, GICT), MP-DNA, MP-RNA (simultaneous amplification and testing, SAT) and MP-DNA (real-time polymerase chain reaction, RT-PCR).

RESULTS

Among these 830 children, RT-PCR showed that the positive rate was 36.6% (304/830), in which the positive rate of macrolide resistance (A2063G mutation) accounted for 86.2% of cases (262/304). Using RT-PCR as the standard, MP-RNA (SAT) had the highest specificity (97.5%), and MP-IgM (PA) had the highest sensitivity (74.0%) and Youden index (53.7%). If MP-RNA (SAT) was combined with MP-IgM (PA), its Kappa value (0.602), sensitivity (84.2%), specificity (78.7%) and Youden index (62.9%) were higher than those of single M. pneumoniae detection.

CONCLUSIONS

Our research indicated that a combination of MP-RNA (SAT) plus MP-IgM (PA) might lead to reliable results as an early diagnostic method for children with clinical manifestations of Mycoplasma pneumoniae pneumonia.

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.

Mycoplasma pneumoniae may cause dyspnoea and hospitalisations in young healthy adults

Polymerase chain reaction (PCR)-based diagnostics for Mycoplasma pneumoniae (M. pneumoniae) from the respiratory tract has become widely available, but the interpretation of the results remains unclear. M. pneumoniae has been suggested to cause mainly mild and self-limiting infections or asymptomatic carriage. However, systematic analyses of the association between PCR results and clinical findings are scarce. This study aimed to clarify the clinical features of PCR-positive M. pneumoniae infections in a hospital setting. We reviewed 103 PCR-positive patients cared for in a university hospital during a 3-year period. Data on age, sex, health condition, acute symptoms, other pathogens found, laboratory and X-ray results and treatments were collected. Over 85% of the patients had a triad of typical symptoms: fever, cough and shortness of breath. Symptoms in the upper respiratory tract were rare. In 91% of the cases, M. pneumoniae was the only pathogen found. The highest incidence was found in the age group of 30–40 years, and 68% of the patients did not have any underlying diseases. Most patients were initially empirically treated with beta-lactam antibiotics and needed 2–4 changes in their treatment. Only 6% were discharged without an antibiotic effective against M. pneumoniae. This study shows that M. pneumoniae often led to hospitalisation and that patients needed appropriate antimicrobial treatment to recover. Mixed infections were rare, and situations that could be interpreted as carriage did not occur.

Why COVID-19 is less frequent and severe in children: a narrative review

BACKGROUND

Despite the streaks of severity, severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) infection is, in general, less frequent and severe in children than in adults. We searched for causal evidence of this mystery.

DATA SOURCES

An extensive search strategy was designed to identify papers on coronavirus disease 2019 (COVID-19). We searched Ovid MEDLINE, PubMed, EMBASE databases, and Cochrane library and carried out a review on the causes of this dilemma.

RESULTS

Our searches produced 81 relevant articles. The review showed that children accounted for a lower percentage of reported cases, and they also experienced less severe illness courses. Some potential explanations, including the tendency to engage the upper airway, the different expression in both receptors of angiotensin-converting enzyme and renin-angiotensin system, a less vigorous immune response, the lower levels of interleukin (IL)-6, IL-10, myeloperoxidase, and P-selectin and a higher intracellular adhesion molecule-1, a potential protective role of lymphocytes, and also lung infiltrations might have protective roles in the immune system-respiratory tract interactions. Finally, what have shed light on this under representation comes from two studies that revealed high-titer immunoglobulin-G antibodies against respiratory syncytial virus and mycoplasma pneumonia, may carry out cross-protection against SARS-CoV-2 infection, just like what suggested about the vaccines.

CONCLUSIONS

These results require an in-depth look. Properties of the immune system including a less vigorous adaptive system beside a preliminary potent innate response and a trained immunity alongside a healthier respiratory system, and their interactions, might protect children against SARS-CoV-2 infection. However, further studies are needed to explore other possible causes of this enigma.

Mycoplasma pneumoniae Infections: Pathogenesis and Vaccine Development

Mycoplasma pneumoniae is a major causative agent of community-acquired pneumonia which can lead to both acute upper and lower respiratory tract inflammation, and extrapulmonary syndromes. Refractory pneumonia caused by M. pneumonia can be life-threatening, especially in infants and the elderly. Here, based on a comprehensive review of the scientific literature related to the respective area, we summarize the virulence factors of M. pneumoniae and the major pathogenic mechanisms mediated by the pathogen: adhesion to host cells, direct cytotoxicity against host cells, inflammatory response-induced immune injury, and immune evasion. The increasing rate of macrolide-resistant strains and the harmful side effects of other sensitive antibiotics (e.g., respiratory quinolones and tetracyclines) in young children make it difficult to treat, and increase the health risk or re-infections. Hence, there is an urgent need for development of an effective vaccine to prevent M. pneumoniae infections in children. Various types of M. pneumoniae vaccines have been reported, including whole-cell vaccines (inactivated and live-attenuated vaccines), subunit vaccines (involving M. pneumoniae protein P1, protein P30, protein P116 and CARDS toxin) and DNA vaccines. This narrative review summarizes the key pathogenic mechanisms underlying M. pneumoniae infection and highlights the relevant vaccines that have been developed and their reported effectiveness.

Arthritis associated with Mycoplasma pneumoniae in a pediatric patient: A case report

INTRODUCTION

Mycoplasma pneumoniae (MP) infection in infants is usually overlooked and it might result in important complications if left untreated. MP-induced arthritis is probably the least common extrapulmonary manifestation and frequently leads to delays in the diagnosis.

PATIENT CONCERNS

We report the case of a 2-year-old female child admitted in our clinic for prolonged fever (onset 2 weeks before the admission), for which the general practitioner established the diagnosis of acute pharyngitis and recommended antibiotics. But the fever persisted and the patient was referred to a pediatrician.

DIAGNOSIS

The laboratory tests revealed leukocytosis with neutrophilia, elevated C-reactive protein and liver cytolysis. The blood and urine cultures, as well as the serological hepatitis B and C, toxoplasmosis, Epstein Barr virus, Rubella, Herpes virus, and cytomegalovirus were negative. The chest X-ray established the diagnosis of pneumonia. The fever persisted for approximately 2 weeks after admission. On the 2nd week of admission, the patient began to experience gait difficulties complaining of pain in the right hip and ankle. The cardiology and pneumology consults revealed no pathological findings. The evolution was favorable after the initiation of Levofloxacin and MP infection was detected as we suspected. Moreover, the ultrasound of the hip revealed a mild joint effusion, while the ankle joint appeared to be normal at ultrasound. Thus, we established the diagnosis of hip and ankle arthritis based on the clinical and ultrasound findings.

INTERVENTIONS

Levofloxacin by vein was continued for 5 days, replaced afterwards with clarithromycin orally for 2 weeks.

OUTCOMES

The gait difficulties persisted for approximately 5 months from the initial diagnosis, and improved once the titer of immunoglobulin M anti-MP antibodies lowered considerably. After more than 8 months, the patient was completely asymptomatic and the immunoglobulin M anti-MP was close to the normal range.

CONCLUSION

The awareness of MP-induced arthritis in children represents the cornerstone in preventing diagnostic delays and initiating the proper treatment.

Susceptibility Analysis in Several Mouse Strains Reveals Robust T-Cell Responses After Mycoplasma pneumoniae Infection in DBA/2 Mice

Mycoplasma pneumoniae (Mp) is a highly contagious respiratory pathogen responsible for human community-acquired pneumonia. The number of antibiotic-resistant Mp strains is increasing; therefore, to develop novel therapeutics, it is crucial to precisely understand the pathogenesis of mycoplasma pneumonia. Herein, we examined the susceptibility and response to Mp among eight inbred mouse strains. Following infection, the bacterial load in the bronchoalveolar lavage fluid (BALF) from DBA/2 mice was higher than that in the other tested strains such as BALB/c mice, which are frequently used in Mp research. In contrast, the numbers of CD45⁺ immune cells and neutrophils in BALF were comparable between BALB/c and DBA/2 mice, with lower numbers observed in C57BL/6J and CBA/N mice than in BALB/c mice. Among the tested strains, the BALF level of interleukin 12 subunit p40 was highest in DBA/2 mice; however, significant differences in other cytokines levels were not observed between BALB/c and DBA/2 mice. After Mp infection, Mp-specific Th1 and Th17 responses were significantly enhanced in DBA/2 mice when compared with BALB/c mice. Furthermore, prior infection with Mp increased the number of neutrophils in BALF after the reinfection of DBA/2 mice through an Mp-specific CD4⁺ T cell-dependent mechanism. Thus, DBA/2 may be an appropriate strain for evaluating Mp infection. Moreover, a comparison of responses revealed by various inbred mouse strains could be useful for elucidating the pathogenesis of Mycoplasma pneumonia.

Current perspectives on atypical pneumonia in children

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

Molecular Detection and Evaluation of MLـ Resistance M. Pneumoniae Associated with Mutation in 23S RNA Gene among Iranian Patients with Respiratory Infections

Background

Mycoplasma pneumoniae is a common cause of community-acquired pneumonia. The global increased resistance of M. pneumoniae strains to macrolide (ML) has become a worrisome health problem. The widespread use of these medications has led to increased rate of reported ML-resistant M. pneumoniae (MRMP) throughout the world. This study was aimed to evaluate the resistance of M. pneumoniae against erythromycin due to mutations in the 23S rRNA gene of patients with respiratory infections in Iran.

Methods

In this study, 100 samples of throat swab from a patient with respiratory problems were collected. After the cultured of all samples in M. pneumonia-specific PPLO medium, PCR technique was performed with specific primers. Afterwards, the broth micro-dilution MIC assay was employed. Finally, the PCR product of the 23S rRNA gene was sequenced to detect mutations of domain V in 23S rRNA gene of MRMP.

Results

It was found that 17 cases (17%) were positive for mycoplasma genus and six cases (6%) positive for M. pneumoniae species. Also, analysis of the sequence of 23S rRNA gene, revealed that one of the samples had mutations at positions A2431G and G2491A. All positive samples M. pneumoniae with 23S rRNA gene were sensitive to erythromycin.

Conclusion

These use of these antibiotics should be limited to prevent the emergence of MRMP in Iran.

Accurate, rapid and low-cost diagnosis of Mycoplasma pneumoniae via fast narrow-thermal-cycling denaturation bubble-mediated strand exchange amplification

Mycoplasma pneumoniae is a strong infectious pathogen that may cause severe respiratory infections. Since this pathogen may possess a latent period after infection, which sometimes leads to misdiagnosis by traditional diagnosis methods, the establishment of a rapid and sensitive diagnostic method is crucial for transmission prevention and timely treatment. Herein, a novel detection method was established for M. pneumoniae detection. The method, which improves upon a denaturation bubble-mediated strand exchange amplification (SEA) that we developed in 2016, is called accelerated SEA (ASEA). The established ASEA achieved detection of 1% M. pneumoniae genomic DNA in a DNA mixture from multiple pathogens, and the limit of detection (LOD) of ASEA was as low as 1.0 × 10^-17 M (approximately 6.0 × 10³ copies/mL). Considering that the threshold of an asymptomatic carriage is normally recommended as 1.0 × 10⁴ copies/mL, this method was able to satisfy the requirement for practical diagnosis of M. pneumoniae. Moreover, the detection process was finished within 20.4 min, significantly shorter than real-time PCR and SEA. Furthermore, ASEA exhibited excellent performance in clinical specimen analysis, with sensitivity and specificity of 96.2% and 100%, respectively, compared with the "gold standard" real-time PCR. More importantly, similar to real-time PCR, ASEA requires only one pair of primers and ordinary commercial polymerase, and can be carried out using a conventional fluorescence real-time PCR instrument, which makes this method low-cost and easy to accomplish. Therefore, ASEA has the potential for wide use in the rapid detection of M. pneumoniae or other pathogens in large numbers of specimens. Graphical abstract.

Viral and bacterial coinfection among hospitalized children with respiratory tract infections

BACKGROUND

The epidemiology of Mycoplasma pneumoniae (MP) and local dominant etiologies of pathogens that cause respiratory tract infections (RTIs) among central China children (≤14 years old) hospitalized are poorly understood.

METHODS

A total of 10,429 specimens were analyzed, and IgM antibodies against 9 respiratory pathogens including MP were detected using indirect immunofluorescence assay from serum.

RESULTS

It showed that 59.3% of the enrolled children were positive for at least 1 pathogen; highest detection rates included those between 3 and <6 years of age (70.4%), female (63.2%), and who were hospitalized in 2014 (80.9%). The most predominant pathogen was MP (45.6%), followed by Parainfluenza viruses (PIVs) (22.6%) and influenza B viruses (IFVB) (14.7%). Coinfection was observed in 2,907 specimens (27.9%); the coinfection combination containing MP and PIVs had the highest detection rate of 15%, followed by MP and IFVB as well as IFVB and PIVs.

CONCLUSIONS

MP was the most commonly detected bacteria among hospitalized children, which should be included in the differential diagnosis for hospitalized children with RTI. These findings will contribute to the effective prevention and therapeutic approaches of pathogens among local children suffering from RTI.

Severe Mycoplasma pneumoniae pneumonia requiring intensive care in children, 2010-2019

BACKGROUND/PURPOSE

Despite the high prevalence of Mycoplasma pneumoniae infections, reports on severe life-threatening M. pneumoniae pneumonia (MPP) in children are limited.

METHODS

We retrospectively enrolled pediatric patients with PCR-positive MPP requiring ICU admission in a children's hospital in Taipei, Taiwan from Jun 2010 to October 2019. Clinical manifestations and laboratory data of severe MPP were analyzed. Macrolide susceptibility was determined by genotyping, and its relationship with clinical manifestations was also analyzed.

RESULTS

Approximately 5% (34/658) children hospitalized for MPP required ICU admission. Compared with non-ICU cases (n = 291), ICU cases (n = 34) were associated with more underlying conditions, more pleural effusion, longer fever duration, longer hospital stay, the requirement of second-line antibiotic treatment, and delayed effective and second-line antibiotic treatment. Macrolide resistance was similar in ICU and non-ICU groups (53% vs 53%; p = 0.986). In severe MPP, patients requiring endotracheal intubation were associated with more septic shock, empyema, ARDS, prolonged fever after effective antibiotic treatment, delayed second-line and effective antibiotic treatment. In 18 of the 22 patients with pleural fluid analysis, the pleural effusion was alkaline (pH > 7.7) and lymphocyte-predominant.

CONCLUSION

M. pneumoniae infection can cause severe life-threatening pneumonia in children. Delayed effective and second-line antibiotic treatments are associated with severe life-threatening MPP.

Distribution characteristics of serum β2-microglobulin between viral and bacterial lower respiratory tract infections: a retrospective study

BACKGROUND

Lower respiratory tract infection (LRTI) is one of the leading cause of death in children under 5 years old around the world between 1980 and 2016. Distinguishing between viral and bacterial infection is challenging when children suffered from LRTI in the absence of pathogen detection. The aim of our study is to analyze the difference of serum β2-microglobulin (β2-MG) between viral LRTI and bacterial LRTI in children.

METHODS

This retrospective study included children with LRTI caused by a single pathogen from Yancheng Third People's Hospital, Yancheng, China, between January 1, 2016 and December 31, 2019. Participants were divided into the younger group (1 year old ≤ age < 3 years old) and the older group (3 years old ≤ age < 5 years old) for subgroup analysis.

RESULTS

A total of 475 children with LRTI caused by common respiratory pathogens were identified. In the younger group as well as the older group, the serum level of β2-MG in respiratory syncytial virus, influenza A virus and influenza B virus groups were significantly increased compared to that in the Mycoplasma pneumoniae group. Compared with Streptococcus pneumoniae infection group, the serum β2-MG level of respiratory syncytial virus, influenza A virus and influenza B virus groups were significantly higher in children between 1 and 3 years old.

CONCLUSIONS

The serum β2-MG may distinguish viral infection from bacterial infection in children with LRTI.

Community-acquired pneumonia: aetiology, antibiotic resistance and prospects of phage therapy

Bacteria are the most common aetiological agents of community-acquired pneumonia (CAP) and use a variety of mechanisms to evade the host immune system. With the emerging antibiotic resistance, CAP-causing bacteria have now become resistant to most antibiotics. Consequently, significant morbimortality is attributed to CAP despite their varying rates depending on the clinical setting in which the patients being treated. Therefore, there is a pressing need for a safe and effective alternative or supplement to conventional antibiotics. Bacteriophages could be a ray of hope as they are specific in killing their host bacteria. Several bacteriophages had been identified that can efficiently parasitize bacteria related to CAP infection and have shown a promising protective effect. Thus, bacteriophages have shown immense possibilities against CAP inflicted by multidrug-resistant bacteria. This review provides an overview of common antibiotic-resistant CAP bacteria with a comprehensive summarization of the promising bacteriophage candidates for prospective phage therapy.

Periodic Genotype Shifts in Clinically Prevalent Mycoplasma pneumoniae Strains in Japan

Nationwide increases in Mycoplasma pneumoniae pneumonia cases in Japan were reported in 2011, 2012, 2015, and 2016. In this study, we isolated 554 M. pneumoniae strains in 4 areas in Japan (Kanagawa, Okayama, Osaka, and Saitama) between 2006 and 2019, and performed genotyping analysis. More than 80% of the strains isolated in 2011 and 2012 harbored type 1 p1 adhesin gene; however, strains harboring type 2 or its variant p1 gene increased in 2015 and 2016 and dominated after 2017. These findings suggested that a shift in the prevalent genotype of M. pneumoniae clinical strains occurred recently in Japan. More than 90% of the type 1 strains isolated after 2010 harbored macrolide-resistance mutations in their 23S rRNA gene, whereas most type 2 lineage strains had no such mutations. Consequently, the increase in type 2 lineage strains in Japan has reduced the macrolide resistance rate of clinical M. pneumoniae strains. During this analysis, we also identified M. pneumoniae strains carrying a novel variant type 1 p1 gene, and we classified it as type 1b. We then sequenced the genomes of 81 selected M. pneumoniae strains that we collected between 1976 and 2017 in Japan, and compared them with 156 M. pneumoniae genomes deposited in public databases to provide insights into the interpretation of M. pneumoniae genotyping methods, including p1 typing, multiple-locus variable-number tandem repeat analysis (MLVA), multi-locus sequence typing (MLST), and typing by 8 single-nucleotide polymorphism markers (SNP-8). As expected, p1 typing, MLST, and SNP-8 results exhibited good correlation with whole-genome SNP analysis results in terms of phylogenetic relationships; however, MLVA typing results were less comparable to those of the other methods. MLVA may be useful for the discrimination of strains derived from a single outbreak within a limited area; however, is not reliable for classification of strains collected from distantly separated areas at different time points. This study showed the usefulness of genome-based comparison of M. pneumoniae for molecular epidemiology. Genome sequencing of more strains will improve our understanding of global propagation routes of this pathogen and evolutionary aspects of M. pneumoniae strains.

The Prevalence of 23S rRNA Mutations in ML-Resistant M. pneumoniae Isolates to Clarithromycin in Patients with Respiratory Infections

BACKGROUND

Mycoplasma pneumoniae is one of the widespread causes of community-acquired pneumonia (CAP). Over recent years, the widespread use of macrolides has led to the emergence of macrolide-resistant M.pneumoniae (MRMP) resulted from mutations at specific positions of domain V of the 23S rRNA gene.

METHODS

We collected 100 samples of throat swabs from patients with respiratory infections. After extraction of DNA from bacterial cell cultured in PPLO broth media using Roche kit (Germany), the PCR was performed on specific samples of M. pneumoniae using specific primers for 23S rRNA gene.Afterwards, for positive samples, minimum inhibitory concentration (MIC) was determined using the broth microdilution with Clarithromycin. Finally, the PCR product was sequenced to detect mutations related to macrolide resistance in domain V of 23S rRNA .

RESULTS

According to the analysis of the sequenced PCR product of M. pneumoniae 23S rRNA gene using Clustalw2 online software, one of the samples were shown to have a mutation at A2431G and G2491A positions. The MIC measurement also revealed that all isolates were sensitive to Clarithromycin, and there was no macrolide resistance to Clarithromycin in all isolates.

CONCLUSION

Sequence analysis of the 23S rRNA gene in M. pneumoniae , revealed no macrolide resistance of M. pneumoniae to Clarithromycin. Thus, the use of these antibiotics should be restricted to prevent the development of macrolide-resistant M. pneumoniae in Iran.

Mycoplasma pneumoniae in Children With and Without Community-acquired Pneumonia. What do PCR and Serology Say?

BACKGROUND

IgM titers of Mycoplasma pneumoniae can remain high for months or years, and specific DNA can be detected in asymptomatic people.

METHODS

We compared the performance of serology and PCR in children with and without community-acquired pneumonia (CAP) for the diagnosis of M. pneumoniae.

RESULTS

In children with CAP, a positive test by M. pneumoniae (PCR and/or paired serology or both) were found in 13.9%. Of these, 10.3% were positive by multiplex PCR (Seeplex-Seegen), and 6.7% exhibited quadrupled titers (22 for IgG, 6 for IgM and 5 for both). Both tests were positive in 2.8% of cases. In the group without CAP, 3.3% were positive by PCR. Thirty-two percent of children with CAP and 38.3% of healthy children had IgM titers >11 in the acute phase.

CONCLUSIONS

The detection of IgM is not useful for diagnosing acute M. pneumoniae infection, and a positive PCR result can be due to colonization and not infection. New and better diagnostic techniques are required.

Human adenovirus Coinfection aggravates the severity of Mycoplasma pneumoniae pneumonia in children

BACKGROUND

Mycoplasma pneumoniae (M. pneumoniae) is an important pathogen of community-acquired pneumonia (CAP) in children. The coinfection rate of M. pneumoniae pneumonia (MPP) can reach 52% in some areas, but the effects of coinfection with different pathogens have not been clearly recognized.

METHODS

The cases of MPP hospitalized in Beijing Children's Hospital from 1/1/2014 to 12/31/2016 were screened. MPP patients coinfected with Human adenovirus (HAdV) were categorized into the research group. Patients with single M. pneumoniae infection were categorized into the control group, matching the research group by age and admission time with a ratio of 1:3. Clinical manifestations, laboratory examinations, and disease severity were compared between these two groups.

RESULTS

A total of 2540 hospitalized MPP cases were screened in Beijing Children's Hospital, among which thirty cases were enrolled in the research group and ninety cases were enrolled in the control group. The results indicated that patients in the research group had longer hospital stays, longer fever durations and a higher rate of dyspnea, as well as a larger proportion applications of oxygen therapy and noninvasive continuous positive airway pressure (NCPAP). No obvious differences were found in lab examinations within the two groups. Regarding disease severity, the proportions of extremely severe pneumonia and severe disease defined by the clinical score system were higher in the research group than in the control group.

CONCLUSION

Compared with single M. pneumoniae infection, MPP coinfected with HAdV in children was relatively more serious.

Vaccination using inactivated Mycoplasma pneumoniae induces detrimental infiltration of neutrophils after subsequent infection in mice

Mycoplasma pneumoniae (Mp) is one of the most common causes of community-acquired pneumonia. Given the emergence and high rates of antibiotic-resistant Mp strains, vaccines that prevent the pneumonia and secondary complications due to Mp infection are urgently needed. Although several studies have shown the protective efficacy of Mp vaccines in human clinical trials, some reports suggest that vaccination against Mp exacerbates disease upon subsequent Mp challenge. Therefore, to develop optimal vaccines against Mp, understanding the immune responses that contribute to post-vaccination exacerbation of inflammation is crucial. Here we examined whether Mp vaccination might exacerbate pneumonia after subsequent Mp infection in mice. We found that vaccination with inactivated Mp plus aluminum salts as an adjuvant induced Mp-specific IgG, Th1 cells, and Th17 cells. Toll-like receptor 2 signaling contributed to the induction of an Mp-specific IgG response and was necessary for Mp-specific Th17-cell-but not Th1-cell-responses in vaccinated mice. In addition, vaccination with inactivated Mp plus aluminum salts suppressed the number of Mp organisms in the bronchoalveolar lavage fluid, indicating that vaccination can reduce Mp infection. However, the numbers of total immune cells and neutrophils in bronchoalveolar lavage fluid after Mp challenge did not differ between vaccinated mice and non-vaccinated control mice. Furthermore, depletion of CD4⁺ T cells prior to Mp challenge decreased pulmonary neutrophil infiltration in vaccinated mice, suggesting that Th1 or Th17 cells (or both) are responsible for the vaccination-induced neutrophil infiltration. These results suggest that, despite reducing Mp infection, vaccination of mice by using inactivated Mp fails to suppress inflammation, such as neutrophil infiltration into the lung, after subsequent Mp infection.

Zinc oxide nanoparticles from Corydalis yanhusuo attenuated the mycoplasmal pneumonia in mice through inhibiting the MAPKs signaling pathway

BACKGROUND

The Mycoplasma pneumoniae (M.pneumoniae) was accounted to 3-10% of total pneumonia incidences. In recent decades, metallic nanoparticles were extensively examined as nano-antibiotics.

OBJECTIVE

In this investigation, we intended to inspect the therapeutic potential of Zinc oxide nanoparticles (ZnONPs) from (Corydalis yanhusuo) C. yanhusuo against the mycoplasma infected pneumonia in mice.

METHODOLOGY

The ZnONPs were formulated via green route technique and characterized by UV-vis spectroscopy, transmission electron microscopy, Fourier transform infrared technique, and atomic force microscopy. The antimicrobial activity of formulated ZnONPs was tested by well diffusion method. The total protein, interleukin-1 (IL-1), interleukin-6 (IL-6), interleukin-8 (IL-8), tumor necrosis factor alpha (TNF-α) and transforming growth factor (TGF) status in the BALF of M. pneumonia infected animals were investigated via kit method. The expressions of ERK1/2, JNK1/2, and NF-κB were examined through the Western blotting. The Histopathological analysis of lung tissues of experimental animals was done.

RESULTS

The UV-vis spectroscopy and TEM examinations were proved the existence of CY-ZnONPs. The formulated CY-ZnONPs were displayed the potential antimicrobial activity. The supplementation of CY-ZnONPs were noticeably diminished the total protein and IL-6, IL-8, and TNF-α levels in the BALF of pneumonia mice. The ERK1/2, JNK1/2, and NF-κB expressions were appreciably diminished in the CY-ZnONPs supplemented mice. It also reduced the inflammatory cells penetration, and exhibited normal tissue arrangements in the lung tissues of pneumonia mice.

CONCLUSION

The findings of this investigation were proved that the synthesized CY-ZnONPs has the potential to ameliorate the M. pneumoniae infected pneumonia in investigational mice.

Epidemiological and clinical analysis of community-acquired Mycoplasma pneumonia in children from a Spanish population, 2010-2015

Introduction and objectives

Mycoplasma pneumoniae (MP) is one of the most common etiological agents of community-acquired pneumonia (CAP) in children. We aimed to describe the clinical and epidemiological characteristics, treatment and outcome of children diagnosed with community-acquired MP pneumonia (CAMP) in a tertiary hospital in Valencia, Spain.

Material and methods

Medical records of children <14 years with CAMP were retrospectively reviewed from January 2010 to December 2015. Patients with radiological evidence of pneumonia and microbiological confirmation of MP (PCR from nasopharyngeal swab and/or serum specific IgM) were considered CAMP.

Results

One hundred and sixty two children were diagnosed with CAMP; median age 6 years (IQR: 4-9). The positive MP test rate among children with CAP progressively increased with age as did the empirical use of macrolides. There were two peaks of cases in 2011 and in 2015, being July, August, November and December the seasons with the higher number of cases. The most frequent radiological pattern was segmental infiltrate (62.3%) and 22 (13.6%) children had pleural effusion. It was noteworthy the mild symptomatology and low levels of inflammatory parameters that children with CAMP had. A macrolide was empirically initiated in 68.5% of cases. Hospital admission rate was inversely proportional to patient's age.

Conclusions

According to this study, older, less symptomatic patients and with lower inflammatory parameters had the greatest rate of MP infection among children with CAP and thus they could benefit of empiric macrolide therapy. Therefore, knowing the epidemiology of a geographical area may be important for the management of CAP in children.

Clinical Role of Serum Interleukin-17A in the Prediction of Refractory Mycoplasma pneumoniae Pneumonia in Children

Background

Mycoplasma pneumoniae pneumonia (MPP) is a common community-acquired pneumonia (CAP) in children, which may become refractory MPP (RMPP) to treatment.

Objective

The purpose of this study was to evaluate the clinical utility of measuring serum interleukin (IL)-17A to predict RMPP.

Patients and Methods

A retrospective clinical study at a single pediatric center included a review of the medical records of all children hospitalized for CAP between November 2015 and October 2019. The diagnosis of MPP was based on clinical presentation, chest radiography, and measurement of serum anti-Mycoplasma immunoglobulin IgM antibody titer using the microparticle agglutination method or sputum samples for Mycoplasma pneumoniae by PCR. Serum levels of IL-18 and IL-17A were determined by ELISA.

Results

Of the 625 children diagnosed with CAP, there were 154 children with MPP and without underlying diseases who were divided into a non-refractory MPP (NRMPP) group (n = 109) and a RMPP group (n = 45). The RMPP group had a higher incidence of tachypnea, cyanosis, hypoxia, segmental or lobar pneumonia, pleural effusion, and a longer period of hospitalization compared with NRMPP group (all P-values < 0.05). A serum IL-17A level above 10.8 pg/mL was a predictor for RMPP: area under the curve (AUC) 0.822; standard error (SE) 0.039; 95% confidence interval (CI) 0.746–0.897; diagnostic sensitivity and specificity of 77.8% and 77.1%, respectively. An LDH level above 436.5 IU/L and an IL-18 level above 464.5 pg/mL were the second most useful markers for RMPP: AUC 0.775, 0.775; SE 0.038, 0.039; 95% CI 0.700–0.850, 0.698–0.852; sensitivity 77.8%, 82.2%; specificity 62.4%, 59.6%; respectively.

Conclusion

This preliminary study of MPP in a pediatric population has shown that measurement of serum IL-17A may be a useful marker for the predictor of RMPP.