The temporal #sequence of #influenza #H1N1 and #Mycoplasma pneumoniae co-infection causes disease severity in Syrian hamster models

 

Abstract

Introduction: 

Influenza H1N1 virus is one of the most prevalent subtypes among influenza viruses, and co-infection with Mycoplasma pneumoniae (Mp) is frequently documented in clinical respiratory infections. However, the pathological mechanisms underlying the temporal sequence of H1N1-Mp co-infection remain poorly characterized, and relevant animal models are lacking.

Methods: 

In this study, we established a model of influenza H1N1 and Mycoplasma pneumoniae co-infection in Syrian hamsters and infected two pathogens in interval of 72 hours. Clinical manifestations, body temperature, body weight, pathogen loads in nasal, pharyngeal, and anal swabs, as well as blood cytokine profiles were dynamically monitored over 14 days post-infection (dpi). Additionally, tissue pathogen loads, histopathological changes, routine blood parameters, and blood biochemistry indicators were evaluated at 7 and 14 dpi.

Results: 

The results demonstrated that hamsters first infected with H1N1 followed by Mp (F-M group) exhibited significantly more severe histopathological lesions (assessed by HE staining), higher pathogen loads, and dysregulated cytokine responses compared to other infection groups.

Conclusion: 

Our findings highlight the critical role of infection order in determining the severity of H1N1-Mp co-infection, providing novel insights into the temporal dynamics and pathogenic mechanisms of respiratory co-infections.

Source: 

Link: https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2026.1787294/full

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#Macrolide #Resistance and P1 Cytadhesin Genotyping of #Mycoplasma pneumoniae during #Outbreak, #Canada, 2024–2025

 

Abstract

We investigated macrolide resistance and P1 genotypes of Mycoplasma pneumoniae during the 2024–2025 outbreak in Hamilton, Ontario, Canada. Macrolide resistance remained stable at ≈10%–20%, but significant shifts in P1 genotype distribution and resistance rates in P1 types occurred, indicating notable changes in M. pneumoniae molecular epidemiology in Ontario since 2011–2012.

Source: 

Link: https://wwwnc.cdc.gov/eid/article/31/12/25-0872_article

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Post #COVID19 #resurgence of #Mycoplasma pneumoniae infections in French #children (ORIGAMI): a retrospective and prospective multicentre cohort study

 

Summary

Background

Following a decline during the COVID-19 pandemic, Mycoplasma pneumoniae infections resurged in several countries. We aimed to characterise the clinical presentation of paediatric patients admitted to hospital for M pneumoniae during 2023 and 2024 in France.

Methods

We conducted a nationwide, multicentre, retrospective, and prospective observational study across 37 French paediatric hospitals (September, 2023–September, 2024). Children younger than 18 years who were hospitalised with laboratory-confirmed M pneumoniae infection (PCR or serology) were included. Demographics (excluding race), clinical features, laboratory and radiological findings, management, and outcomes data were described and analysed. Logistic regression was used to identify factors associated with paediatric intensive care unit (PICU) admission. The trial was registered at ClinicalTrials.gov (NCT06260371) and is complete.

Findings

We included 969 children and adolescents with M pneumoniae infection (7·3 years [SD 4·5], 426 [44%] of 966 patients were female and 540 [56%] of 966 were male). 936 (97%) of all patients were positive by PCR for M pneumoniae. Pneumonia was diagnosed in 628 (87%) of the 726 patients with respiratory involvement, and cutaneous manifestations were reported in 132 (14%) of 969 patients, including 56 (42%) of 132 who had erythema multiforme. Macrolides were prescribed in 884 (95%) of the 931 patients who were prescribed antibiotics, primarily azithromycin (563 [64%] of 884). Macrolide resistance was detected in one (5%) of the 21 tested samples. In total, 57 (6%) of 969 patients required PICU admission and four (<1%) died. Factors significantly associated with PICU admission included being older than 11 years (adjusted odds ratio 2·0 [95% CI 1·1–3·6]; p=0·023), asthma (2·2 [1·2–4·0]; p=0·0072), other underlying conditions (2·1 [1·2–3·7]; p=0·013), and erythema multiforme (3·7 [1·6–8·8]; 0·0025).

Interpretation

The 2023–2024 M pneumoniae epidemic in France resulted in a substantial paediatric hospitalisation burden. Although severe cases were uncommon, children older than 11 years, those with asthma, other comorbidities, and erythema multiforme were at increased risk of PICU admission. Ongoing surveillance and targeted management strategies are warranted for future epidemics.

Funding

Association Clinique et Thérapeutique Infantile du Val de Marne (ACTIV).

Source: 

Link: https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(25)00598-5/abstract?rss=yes

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Assessment of #serum #parameters caused by the #outbreak of #mycoplasma pneumoniae #pneumonia in #children after #COVID19

Abstract

Mycoplasma pneumonia pneumonia(MPP) is a common respiratory disease that often occurs in children. The purpose of this study was to explore the clinical characteristics of children with mycoplasma pneumoniae pneumonia, the first outbreak after the prevalence of COVID-19 epidemic. Meanwhile, this study also analyzed the predictive value of serum protein indicators and coagulation parameters in the MPP group, as well as the correlation between these indicators. Children with Mycoplasma pneumoniae admitted to the pediatric ward of Chengdu Fifth People’s Hospital from May 2023 to March 2024 were selected. After screening, 411 children who met the research criteria were selected as the study subjects. All of the blood samples were tested for coagulation function, procalcitonin, serum protein and glucose among MPP group and control group. All data were processed for statistical analysis using GraphPad Prism 10.2.3. Comparison of the serum proteins and coagulation function between the MPP group and control group showed that prothrobin time(PT), thrombin time (TT), fibrinogen(Fbg), activated partial thromboplastin time (APTT), international normalized ration(INR), D-Dimer(DD) were significantly higher(P < 0.05) in MPP group. Total protein, albumin, prealbumin, alkaline phosphatase, lactate dehydrogenase, adanosine deaminase, glucose, platelet, procalcitonin also were significantly higher(P < 0.05) in MPP group. A multiple logistic regression analysis showed that the children in MPP group were a statistically significant difference in comparison of TT, Fbg, total protein, albumin, glucose, platelet expression in predicting the development. Then we analyzed the area under the ROC curve and correlation of serum parameters with significant differences in MPP group children. These results indicate that the coagulation function and serum protein of MPP patients who first broke out after the COVID-19 epidemic are different from the previous clinical characteristics, which can be used as a reference for auxiliary diagnosis.

Source: Scientific Reports, https://www.nature.com/articles/s41598-025-13555-6

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#Mycoplasma pneumoniae #Infections in Hospitalized #Children — #USA, 2018–2024

Summary

- What is already known about this topic?

-- Mycoplasma pneumoniae is a common cause of community-acquired pneumonia (CAP) in school-aged children. In the United States, M. pneumoniae infection prevalence decreased during the COVID-19 pandemic and remained low through 2023.

- What is added by this report?

-- The number of hospital discharges of children with M. pneumoniae–associated CAP from U.S. pediatric hospitals increased sharply in 2024, accounting for approximately one half of hospitalized children with CAP. This number included children aged <5 years, a group in which M. pneumoniae infections have historically been less commonly reported. Data on length of hospitalization and intensive care unit admissions indicate that M. pneumoniae infections in 2024 were not more severe than 2018–2023 infections.

- What are the implications for public health practice?

-- Increased awareness among health care providers might improve diagnosis and could guide treatment of M. pneumoniae infections among children of all ages, especially during periodic increases in M. pneumoniae circulation and among children requiring hospitalization.

Abstract

Mycoplasma pneumoniae is a common bacterial cause of respiratory infection and a leading cause of childhood community-acquired pneumonia (CAP). Increases in M. pneumoniae infection occur every 3–5 years. In the United States, M. pneumoniae prevalence decreased during and immediately after the COVID-19 pandemic. Information from 42 U.S. children’s hospitals that provided information to the Pediatric Health Information System, a database of clinical and resource use information, was used to identify discharge diagnostic codes for 2018–2024 indicating M. pneumoniae infection. M. pneumoniae–associated CAP incidence among children aged ≤18 years was significantly higher in 2024 (12.5 per 1,000 hospitalizations) than during 2018–2023 (2.1). During the study period, an M. pneumoniae diagnostic code was listed in 11.5% of pediatric CAP hospitalizations, peaking at 53.8% in July 2024. Among pediatric M. pneumoniae CAP cases, the highest percentage occurred among children aged 6–12 years (42.6%), followed by children aged 2–5 years (25.7%) and 13–18 years (21.1%). The lowest occurred among those aged 12–23 months (6.4%) and 0–11 months (4.2%). M. pneumoniae infections in 2024 were not more severe than 2018–2023 infections, as assessed by length of hospitalization and percentage of patients admitted to an intensive care unit. The increase in M. pneumoniae infections in the United States in 2024 might be higher than previous periodic increases because the susceptible population was larger after sustained low incidence during and immediately after the COVID-19 pandemic. Health care providers should be aware of the periodicity of M. pneumoniae CAP and consider testing for this pathogen as a cause of respiratory illness among children of all ages.

Source: US Centers for Disease Control and Prevention, MMWR, https://www.cdc.gov/mmwr/volumes/74/wr/mm7423a1.htm?s_cid=mm7423a1_e&ACSTrackingID=USCDC_921-DM147954&ACSTrackingLabel=Week%20in%20MMWR%3A%20Vol.%2074%2C%20June%2026%2C%202025&deliveryName=USCDC_921-DM147954

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Increased #Pneumonia-Related #Emergency Department Visits, Northern #Italy

Abstract

An increase in pneumonia-related emergency department visits was observed in Lombardy, northern Italy, during June–October 2024. Viral causes appear insufficient to explain the increase, suggesting a bacterial cause. Mycoplasma pneumoniae and Bordetella pertussis emerged as possible causes when other surveillance systems were consulted, but the reasons behind this trend remain unknown.

Source: US Centers for Disease Control and Prevention, https://wwwnc.cdc.gov/eid/article/31/5/24-1790_article

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#Mycoplasma pneumoniae #infection in #adult inpatients during the 2023–24 #outbreak in #France (MYCADO): a national, retrospective, observational study

Summary

Background

An epidemic of Mycoplasma pneumoniae infection has been observed in France since September, 2023. We aimed to describe the characteristics of adults hospitalised for M pneumoniae infection and identify factors associated with severe outcomes of infection.

Methods

MYCADO is a retrospective observational study including adults hospitalised for 24 h or more in 76 hospitals in France for a M pneumoniae infection between Sept 1, 2023, and Feb 29, 2024. Clinical, laboratory, and imaging data were collected from medical records. We identified factors associated with severe outcomes of infection, defined as a composite of intensive care unit (ICU) admission or in-hospital death, using multivariable logistic regression.

Findings

1309 patients with M pneumoniae infection were included: 718 (54·9%) were men and 591 (45·1%) were women; median age was 43 years (IQR 31–63); 288 (22·0%) had chronic respiratory failure; 423 (32·3%) had cardiovascular comorbidities; and 105 (8·0%) had immunosuppression. The most common symptoms were cough (1098 [83·9%]), fever (1023 [78·2%]), dyspnoea (948 [72·4%]), fatigue (550 [42·0%]), expectorations (473 [36·1%]), headache (211 [16·1%]), arthromyalgia (253 [19·3%]), ear, nose, and throat symptoms (202 [15·4%]), diarrhoea (138 [10·5%]), and vomiting (132 [10·1%]). 156 (11·9%) of 1309 patients had extra-respiratory manifestations, including 36 (2·8%) with erythema multiforme, 19 (1·5%) with meningoencephalitis, 44 (3·4%) with autoimmune haemolytic anaemia, and 17 (1·3%) with myocarditis. The median hospital stay was 8 days (IQR 6–11). 424 (32·4%) patients had a severe outcome of infection, including 415 (31·7%) who were admitted to the ICU and 28 (2·1%) who died in hospital. Those more likely to present with severe outcomes of infection were patients with hypertension, obesity, chronic liver failure, extra-respiratory manifestations, pulmonary alveolar consolidation or bilateral involvement on CT scan, as well as elevated inflammatory markers, lymphopenia or neutrophilic polynucleosis, and those who did not versus did receive any antibiotic active against M pneumoniae before admission.

Interpretation

This national, observational study highlighted unexpected, atypical radiological presentations, a high proportion of transfers to the ICU, and an association between severity and delayed administration of effective antibiotics. This should remind clinicians that no radiological presentation can rule out M pneumoniae infection, and encourage them to reassess patients early after prescribing a β-lactam, or even to discuss prescribing macrolides as first-line treatment in the context of an epidemic.

Source: Lancet Infectious Diseases, https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(24)00805-3/abstract?rss=yes

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#China, National sentinel #surveillance of acute #respiratory infectious #diseases (Week 52, 2024)

{Excerpt}

In the 52nd week of 2024 ( December 23rd to December 29th ), respiratory samples from outpatient influenza-like cases and hospitalized severe acute respiratory infection cases collected in sentinel hospitals across the country (excluding Hong Kong, Macao and Taiwan) were tested for 10 viruses including the new coronavirus, influenza virus, respiratory syncytial virus, adenovirus, human metapneumovirus, parainfluenza virus, common coronavirus, bocavirus, rhinovirus and enterovirus, as well as multiple respiratory pathogens including Mycoplasma pneumoniae.

1. Test results

The pathogens detected positive in respiratory samples of influenza-like cases in outpatient and emergency departments of sentinel hospitals were mainly influenza virus, human metapneumovirus, and rhinovirus; the pathogens detected positive in respiratory samples of hospitalized severe acute respiratory infection cases were mainly influenza virus, Mycoplasma pneumoniae, and human metapneumovirus. The specific results are shown in Table 1 , Figure 1 , and Figure 2. The test results showed differences between the north and south regions and between different age groups, as shown in Table 2 and Table 3 .

2. Analysis and health tips

The results showed that the overall acute respiratory infectious diseases are showing a continuous upward trend, and the trends of infections caused by different pathogens are different. Influenza is generally in the seasonal epidemic period, and the influenza virus positive rate is rising rapidly. Among them, the influenza virus positive rate of outpatient influenza-like cases nationwide increased by 6.2% compared with last week ; the level of influenza activity varies among provinces, and the increase in northern provinces is slightly obvious, but still lower than the same period last year. Recently, the positive rate of respiratory syncytial virus in cases aged 0 to 4 years and the positive rate of human metapneumovirus in cases aged 14 years and below have fluctuated upward, and the upward trend is more obvious in northern provinces. The positive rate of rhinovirus continues to decline; the positive rate of Mycoplasma pneumoniae in northern provinces continues to decline, and Mycoplasma pneumoniae infection in southern provinces is still at a low level. The positive rate of adenovirus fluctuates and declines. Other respiratory pathogens such as the new coronavirus are at a low epidemic level.

We are still in the season of high incidence of respiratory infectious diseases. In order to reduce the spread of diseases and reduce the harm of diseases, the public is advised to take the following protective measures:

( 1 ) Maintain good hygiene habits: cover your mouth and nose with a tissue, towel or elbow when coughing or sneezing; wash your hands frequently with soap and water for at least 20 seconds, or use alcohol-based hand sanitizer; avoid touching your eyes, nose, and mouth with your hands to reduce the risk of pathogen transmission.

( 2 ) Promote a healthy lifestyle: A balanced diet, moderate exercise and adequate rest can help enhance immunity. If you have a fever, cough or other respiratory infection symptoms, it is recommended to rest at home, avoid going to work or school while sick, wear a mask when in contact with family members, and keep the room well ventilated.

( 3 ) Wear a mask scientifically: Wear a mask throughout the medical treatment process; it is recommended to wear a mask in crowded places or when taking public transportation (such as airplanes, trains, subways, etc.).

( 4 ) Actively vaccinate: People with weak immunity (such as pregnant women, young children, the elderly and patients with chronic diseases) should be vaccinated with relevant vaccines to prevent respiratory infectious diseases in a timely manner according to vaccination guidelines, including influenza vaccine, new coronavirus vaccine and pneumococcal vaccine. In particular, as the level of influenza activity has increased recently, people of appropriate age who have not received influenza vaccination should be vaccinated as soon as possible. 

(...)

Source: China Centers for Disease Control and Prevention, https://www.chinacdc.cn/jksj/jksj04_14275/202501/t20250102_303654.html

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