Mycoplasma pneumoniae P1 Genotype Indicates Severity of Lower Respiratory Tract Infections in Children

Unravelling distinct patterns of metagenomic surveillance and respiratory microbiota between two P1 genotypes of Mycoplasma pneumoniae

To unravel distinct patterns of metagenomic surveillance and respiratory microbiota between Mycoplasma pneumoniae (M. pneumoniae) P1-1 and P1-2 and to explore the impact of the COVID-19 pandemic on epidemiological features, we conducted a multicentre retrospective study which spanned 90,886 pneumonia patients, among which 3164 cases M. pneumoniae were identified. Our findings revealed a concurrent outbreak of M. pneumoniae, with the positivity rate rising sharply to 9.62% from July 2023, compared to the 0.16% to 4.06% positivity rate observed during the 2020-2022 COVID-19 pandemic. P1-1 had a higher odds ratio of co-detecting opportunistic pathogens. However, no significant differences were observed in the co-detection odds ratio between children and other age groups in P1-2. This study is the first to demonstrate differences in relative abundance, diversity of respiratory microbiota and co-detection rate of opportunistic pathogen between M. pneumoniae P1-1 and P1-2. Through bronchoalveolar lavage (BAL) metagenomic and host transcriptomic analyses, we identified variations in co-detection rates of M. pneumoniae P1-1 genotype with opportunistic pathogens like S. pneumoniae, alterations in respiratory microbiota composition, lung inflammation, and disruption of ciliary function. Consistent with the results of host transcriptome, we found that P1-1 infections were associated with significantly higher rates of requiring respiratory support and mechanical ventilation compared to P1-2 infections (Fisher's exact test, p-value = 0.035/0.004). Our study provides preliminary evidence of clinical severity between M. pneumoniae strains, underscoring the need for ongoing research and development of targeted therapeutic strategies.

Epidemiology and Diagnostic Accuracy of Respiratory Pathogens in Pediatric Populations: Insights From Global Studies

Lower respiratory tract infections (LRTIs) are the most common cause for going to the doctor's at pediatric age. Respiratory infections are still of interest because they are widespread, significantly impact public health by potentially leading to pandemics, drive antimicrobial resistance through antibiotic misuse, more often spread globally due to traveling, and benefit from ongoing advancements in diagnostics and research for better management. This paper's main aim was to offer a systematic review of the literature published over the last 10 years on the etiology of LRTIs. The search strategy was based on reviewing original articles, systematic reviews, position papers, and guidelines published in MEDLINE, EMBASE, Cochrane Library, and PubMed. The review was previously registered with PROSPERO. The final review included 27 articles that met the eligibility criteria (studies identifying the etiology of inferior respiratory infections in children, according to the WHO definition, published in the last 10 years). Statistical analysis was performed using Microsoft Excel Version 2406 (Microsoft Corporation, Redmond, Washington, USA) and SPSS Statistics V.23 (IBM Corp., Armonk, New York, USA). The total number of patients was 2,193,978. Eight articles focused on children younger than five years, and two included children under the age of two. The results revealed that Mycoplasma pneumoniae and respiratory syncytial virus (RSV) are significant respiratory pathogens with seasonal peaks and age-specific prevalence and that nasopharyngeal aspirates (NPAs) are more reliable than throat swabs for confirming infections due to their higher positive predictive value (PPV). The impact of COVID-19 interventions led to reduced infections from RSV, adenovirus, and influenza viruses, but an increase in rhinovirus post-reopening, with high co-infection rates. Co-infections are common, particularly with pathogens like human bocavirus (HBoV) and RSV, underscoring the need for comprehensive diagnostic approaches. The impact of non-pharmaceutical interventions during the COVID-19 pandemic significantly reduced the prevalence of many respiratory pathogens, except for rhinovirus, which increased post-reopening. Understanding these dynamics is crucial for managing respiratory infections, especially in pediatric populations.

Molecular epidemiology of Mycoplasma pneumoniae pneumonia in children, Wuhan, 2020-2022

BACKGROUND

Mycoplasma pneumoniae (M. pneumoniae) is an important pathogen of community-acquired pneumonia in children. The factors contributing to the severity of illness caused by M. pneumoniae infection are still under investigation. We aimed to evaluate the sensitivity of common M. pneumoniae detection methods, as well as to analyze the clinical manifestations, genotypes, macrolide resistance, respiratory microenvironment, and their relationship with the severity of illness in children with M. pneumoniae pneumonia in Wuhan.

RESULTS

Among 1,259 clinical samples, 461 samples were positive for M. pneumoniae via quantitative polymerase chain reaction (qPCR). Furthermore, we found that while serological testing is not highly sensitive in detecting M. pneumoniae infection, but it may serve as an indicator for predicting severe cases. We successfully identified the adhesin P1 (P1) genotypes of 127 samples based on metagenomic and Sanger sequencing, with P1-type 1 (113/127, 88.98%) being the dominant genotype. No significant difference in pathogenicity was observed among different genotypes. The macrolide resistance rate of M. pneumoniae isolates was 96% (48/50) and all mutations were A2063G in domain V of 23S rRNA gene. There was no significant difference between the upper respiratory microbiome of patients with mild and severe symptoms.

CONCLUSIONS

During the period of this study, the main circulating M. pneumoniae was P1-type 1, with a resistance rate of 96%. Key findings include the efficacy of qPCR in detecting M. pneumoniae, the potential of IgM titers exceeding 1:160 as indicators for illness severity, and the lack of a direct correlation between disease severity and genotypic characteristics or respiratory microenvironment. This study is the first to characterize the epidemic and genomic features of M. pneumoniae in Wuhan after the COVID-19 outbreak in 2020, which provides a scientific data basis for monitoring and infection prevention and control of M. pneumoniae in the post-pandemic era.

The Association between Mycoplasma pneumoniae Genotype and Cutaneous Disease

Mycoplasma pneumoniae (Mp) can cause several extrapulmonary manifestations, most frequently dermatological ones. It is largely unknown whether Mp genotype determines Mp-induced cutaneous disease. The aim of our study was to assess the association between Mp genotype and this clinical outcome. We performed a retrospective study of children referred with signs of acute Mp infection from 1 January 2014 to 31 December 2014. We compared the characteristics of children presenting as cutaneous disease, upper (URTI) and lower respiratory tract infection (LRTI). In addition, we separately analyzed the data of patients presenting with Mp-induced cutaneous disease. We evaluated data from 435 patients (mean age 7.3 years, SD 3.4 years; 52.0% boys) who had Mp PCR-positive pharyngeal swab, P1 genotype and/or multilocus variable-number tandem-repeat analysis (MLVA) genotype defined and no viral co-detection, presenting as cutaneous disease (38/435), URTI (46/435) or LRTI (351/435). The majority of patients had urticarial (55%, 21/38) or maculopapular eruptions (37%, 14/38). We found no association between Mp genotype and clinical outcome of cutaneous disease, nor any specific dermatological presentation. In the group with cutaneous disease, 18% (7/38) required hospital admission because of rash. We found that infection with MLVA-3,6,6,2 strains was more common in admitted patients than in outpatients (40% vs. 4%, p = 0.017) and significantly affected the likelihood of hospital admission in a logistic regression model. The results of our cohort study suggest that Mp genotype does not determine Mp-induced cutaneous disease or a specific dermatological presentation. Nevertheless, infections with certain MLVA strains could induce more severe cutaneous disease requiring hospitalization.

Mycoplasma pneumoniae multilocus variable-number tandem-repeat analysis genotypes are associated with inflammatory biomarker levels in children with lower respiratory tract infections

The multilocus variable-number tandem-repeat analysis (MLVA) typing method is commonly used in Mycoplasma pneumoniae (M. pneumoniae) epidemiology. It remains unknown if clinical manifestations of lower respiratory tract infections (LRTI) in children differ between different MLVA genotypes. We aimed to determine if specific M. pneumoniae MLVA genotypes indicate the severity of LRTI in children. We performed a retrospective study of children younger than 18 years with signs of acute M. pneumoniae LRTI from January 1, 2009, to December 31, 2014. All patients who were PCR-positive for M. pneumoniae from pharyngeal swabs and had MLVA genotype successfully defined were included in the study. We compared the epidemiological and clinical data of children infected with different MLVA genotypes. In total, 429 patients (mean age 7.4 years, SD 3.4 years; 54% boys) met the study inclusion criteria. We compared the data of patients infected with the three most common MLVA types: MLVA-3,5,6,2 (86/429), MLVA-3,6,6,2 (71/429) and MLVA-4,5,7,2 (256/429). MLVA-3,5,6,2-infected patients over 5 years of age presented with a significantly higher median C-reactive protein level (34 vs 23 vs 19 mg/L, p = .008) and a higher median white blood cell count (9.4 vs 7.9 vs 8.5 × 10⁹/L, p = .040) compared to MLVA-3,6,6,2- and MLVA-4,5,7,2-infected patients. No such difference was observed in the group of younger than 5 years. The results from our large cohort indicate that different MLVA genotypes may have different pathogenic potential and that children with MLVA-3,5,6,2 LRTI may present with higher inflammatory marker levels in comparison with other MLVA types.

Molecular Tools for Typing Mycoplasma pneumoniae and Mycoplasma genitalium

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

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.