Gene and cytokine profile analysis of macrolide-resistant Mycoplasma pneumoniae infection in Fukuoka, Japan

Challenges in the treatment of pediatric Mycoplasma pneumoniae pneumonia

Mycoplasma pneumoniae (MP) is an important cause of community-acquired pneumonia in children and young adolescents. Despite macrolide antibiotics effectiveness as a first-line therapy, persistence of fever and/or clinical deterioration sometimes may complicate treatment and may even lead to severe systemic disease. To date, there is no consensus on alternative treatment options, optimal dosage, and duration for treating severe, progressive, and systemic MP pneumonia after macrolide treatment failure. Macrolide-resistant MP pneumonia and refractory MP pneumonia are the two major complex conditions that are clinically encountered. Currently, the vast majority of MP isolates are resistant to macrolides in East Asia, especially China, whereas in Europe and North America, whereas in Europe and North America prevalence is substantially lower than in Asia, varying across countries. The severity of pneumonia and extrapulmonary presentations may reflect the intensity of the host's immune reaction or the dissemination of bacterial infection. Children infected with macrolide-resistant MP strains who receive macrolide treatment experience persistent fever with extended antibiotic therapy and minimal decrease in MP-DNA load. Alternative second-line agents such as tetracyclines (doxycycline or minocycline) and fluoroquinolones (ciprofloxacin or levofloxacin) may lead to clinical improvement after macrolide treatment failure in children. Refractory MP pneumonia reflects a deterioration of clinical and radiological findings due to excessive immune response against the infection. Immunomodulators such as corticosteroids and intravenous immunoglobulin (IVIG) have shown promising results in treatment of refractory MP pneumonia, particularly when combined with appropriate antimicrobials. Corticosteroid-resistant hyperinflammatory MP pneumonia represents a persistent or recrudescent fever despite corticosteroid therapy with intravenous methylprednisolone at standard dosage.

CONCLUSION

 This report summarizes the clinical significance of macrolide-resistant and refractory MP pneumonia and discusses the efficacy and safety of alternative drugs, with a stepwise approach to the management of MP pneumonia recommended from the viewpoint of clinical practice.

WHAT IS KNOWN

• Although MP pneumonia is usually a benign self-limited infection with response macrolides as first line therapy, severe life-threatening cases may develop if additional treatment strategies are not effectively implemented. • Macrolide-resistant and refractory MP pneumonia are two conditions that may complicate the clinical course of MP pneumonia, increasing the risk for exacerbation and even death.

WHAT IS NEW

• This report summarizes the clinical relevance of macrolide-resistant and refractory MP pneumonia and discusses the efficacy and safety of alternative drug therapies. • A practical stepwise approach to the management of MP pneumonia is developed based on a comprehensive analysis of existing evidence and expert opinion.

Structure-Based Virtual Screening, ADMET Properties Prediction and Molecular Dynamics Studies Reveal Potential Inhibitors of Mycoplasma pneumoniae HPrK/P

Mycoplasma pneumoniae pneumonia (MPP) is a frequent cause of community-acquired pneumonia (CAP) in children. The incidence of childhood pneumonia caused by M. pneumoniae infection has been rapidly increasing worldwide. M. pneumoniae is naturally resistant to beta-lactam antibiotics due to its lack of a cell wall. Macrolides and related antibiotics are considered the optimal drugs for treating M. pneumoniae infection. However, clinical resistance to macrolides has become a global concern in recent years. Therefore, it is imperative to urgently identify new targets and develop new anti-M. pneumoniae drugs to treat MMP. Previous studies have shown that deficiencies in HPrK/P kinase or phosphorylase activity can seriously affect carbon metabolism, growth, morphology, and other cellular functions of M. pneumoniae. To identify potential drug development targets against M. pneumoniae, this study analyzed the sequence homology and 3D structure alignment of M. pneumoniae HPrK/P. Through sequence and structure analysis, we found that HPrK/P lacks homologous proteins in the human, while its functional motifs are highly conserved in bacteria. This renders it a promising candidate for drug development. Structure-based virtual screening was then used to discover potential inhibitors among 2614 FDA-approved drugs and 948 bioactive small molecules for M. pneumoniae HPrK/P. Finally, we identified three candidate drugs (Folic acid, Protokylol and Gluconolactone) as potential HPrK/P inhibitors through molecular docking, molecular dynamics (MDs) simulations, and ADMET predictions. These drugs offer new strategies for the treatment of MPP.

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.

Proteomic and Phenotypic Studies of Mycoplasma pneumoniae Revealed Macrolide-Resistant Mutation (A2063G) Associated Changes in Protein Composition and Pathogenicity of Type I Strains

Mycoplasma pneumoniae (MP) is an important respiratory pathogen, the prevalence of macrolide-resistant MP (mainly containing A2063G mutation in 23S rRNA) increased in recent years. Epidemiological studies suggest a higher prevalence of type I resistant (IR) strains than corresponding sensitive (IS/IIS) strains, but not type II resistant (IIR) strains. Here, we aimed to analyze the factors underlying the altered prevalence of IR strains. First, proteomic analyses exhibit the protein compositions were type specific, while more differential proteins were detected between IS and IR (227) than IIS and IIR strains (81). mRNA level detection suggested posttranscriptional regulation of these differential proteins. Differential protein-related phenotypic changes were also detected: (i) P1 abundance was different between genotypes (I < II, IR < IS), the adhesion of MPs showed accordance to P1 abundance within IS and IIS strains; (ii) type I, especially IR, strains had a higher proliferation rate, which is potentially associated with differential proteins participating in glycolysis and one carbon pool metabolisms; (iii) A549 cells infected with IR strains had lower activity of caspase-3 and higher levels IL-8, but the differences were not significant between groups (P > 0.05). Correlations of P1 abundance to caspase-3 activity and proliferation rate to the level of IL-8 were obtained. These results suggest changes in protein composition influenced the pathogenicity of MP, especially in IR strains, which may impact the prevalence of MP strains of different genotypes. IMPORTANCE The prevalence of macrolide-resistant MPs increased the difficulty in treatment of MP infections and posed potential threats to children's health. Epidemiological studies showed a high prevalence of IR-resistant strains (mainly A2063G in 23S rRNA) in these years. However, the trigger mechanisms for this phenomenon are not clear. In this paper, proteomic and phenotypic studies suggest that IR strains have reduced levels of multiple adhesion proteins and increased proliferation rate, which may lead to higher transmission rate of IR strains in the population. This suggests that we should pay attention to the prevalence of IR strains.

Macrolide versus Non-Macrolide in Combination with Steroids for the Treatment of Lobar or Segmental Mycoplasma pneumoniae Pneumonia Unresponsive to Initial Macrolide Monotherapy

In the last few decades, macrolide-resistant Mycoplasma pneumoniae (MRMP) has been increasing in proportion. This study aimed to evaluate the treatment outcomes of children with lobar or segmental MP pneumonia unresponsive to the initial 3−5-day macrolide therapy, who then switched to either a non-macrolide, macrolide + steroid, or a non-macrolide + steroid regimen, according to the 2019 KSPID and KAPARD guideline during the 2019−2020 Mycoplasma epidemic in South Korea. A total of 190 patients <18 years old were admitted during the study period for MP lobar or segmental pneumonia, and 16.8% (n = 32/190) were responsive to the initial macrolide monotherapy, whereas 83.2% (158/190) were refractory. The median age of the patients was 7 (interquartile range [IQR], 5−9) years old and 46.2% (n = 73/158) were male. The overall treatment success rates of non-macrolide, macrolide + steroid, and non-macrolide + steroid groups were 46.2%, 80.8%, and 100.0%, respectively. Patients in the non-macrolide + steroid group had the shortest fever duration after a regimen change of 1 (IQR, 0−3) day compared with patients in the non-macrolide group and macrolide + steroid group; 2 (IQR, 1−4) days and 2 (IQR, 1−3.3) days (p = 0.004), respectively. Follow-up CRP (ß, 0.169; CI, 0.050−0.287; p = 0.006), macrolide + steroid therapy (ß, −1.694; CI, −2.463−−0.925; p < 0.001), and non-macrolide+ steroid therapy (ß, −2.224; CI, −3.321−−1.127; p < 0.001) were shown to be significantly associated with the duration of fever after admission. To conclude, in patients with severe MP pneumonia that failed to respond to the initial macrolide therapy, a non-macrolide + steroid had the highest treatment success rate and a shorter duration of fever.

Global prevalence of resistance to macrolides in Mycoplasma pneumoniae: a systematic review and meta-analysis

OBJECTIVES

To determine the prevalence of resistance to macrolides in Mycoplasma pneumoniae worldwide.

METHODS

Prior to 12 December 2020, PubMed, Web of Science, Scopus and Embase databases were searched for epidemiological studies of M. pneumoniae resistance. Two reviewers independently extracted data from included studies. The extracted data include sampling population, total sampling number, the number of resistant strains and the molecular subtype of resistant strains. The estimate of resistance prevalence was calculated using the random-effects model.

RESULTS

A total of 17 873 strains were obtained from five continents and reported in 98 investigations between 2000 and 2020, with 8836 strains characterized as macrolide resistant. In summary, macrolide-resistant M. pneumoniae was most common in Asia (63% [95% CI 56, 69]). In Europe, North America, South America and Oceania, the prevalence was 3% [2, 7], 8.6% [6, 11], 0% and 3.3%, respectively. Over the last 20 years, the prevalence of macrolide-resistant M. pneumoniae has remained high in China (81% [73, 87]), with a significant increasing trend in South Korea (4% [1, 9] to 78% [49, 93], P < 0.0001). Furthermore, a point mutation at 2063 from A to G was mostly related to M. pneumoniae macrolide resistance. In terms of clinical outcomes, longer cough (mean difference [MD]: 2.93 [0.26, 5.60]) and febrile days (MD: 1.52 [1.12, 1.92]), and prolonged hospital stays (MD: 0.76 [0.05, 1.46]) might be induced by macrolide-resistant M. pneumoniae pneumonia.

CONCLUSIONS

The incidence of macrolide-resistant M. pneumoniae varies globally, with eastern Asia having a greater degree of resistance. However, attention is also required in other areas, and antibiotic alternatives should be considered for treatment in high-prevalence countries.

Refractory Mycoplasma pneumoniae Pneumonia in Children: Early Recognition and Management

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

Clinical Characteristics of Macrolide-Refractory Mycoplasma pneumoniae Pneumonia in Korean Children: A Multicenter Retrospective Study

Mycoplasma pneumoniae is a major causative pathogen of community-acquired pneumonia in children, and the treatment of choice is macrolides. There is an increasing trend in reports of refractory clinical responses despite macrolide treatment due to the emergence of macrolide-resistant M. pneumoniae. Early discrimination of macrolide-refractory M. pneumoniae pneumonia (MrMP) from macrolide-sensitive M. pneumoniae pneumonia (MSMP) is vital; however, testing for macrolide susceptibility at the time of admission is not feasible. This study aimed to identify the characteristics of MrMP in Korean children, in comparison with those of MSMP. In this multicenter study, board-certified pediatric pulmonologists at 22 tertiary hospitals reviewed the medical records from 2010 to 2015 of 5294 children who were hospitalized with M. pneumoniae pneumonia and administered macrolides as the initial treatment. One-way analysis of variance and the Kruskal-Wallis test were used to compare differences between groups. Of 5294 patients (mean age, 5.6 years) included in this analysis, 240 (4.5%), 925 (17.5%), and 4129 (78.0%) had MrMP, macrolide-less effective M. pneumoniae pneumonia, and MSMP, respectively. Compared with the MSMP group, the MrMP group had a longer fever duration, overall (13.0 days) and after macrolide use (8.0 days). A higher proportion of MrMP patients had respiratory distress, pleural effusion, and lobar pneumonia. The mean aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, and C-reactive protein levels were the highest in the MrMP group, along with higher incidences of extrapulmonary manifestations and atelectasis (during and post infection). Pre-existing conditions were present in 17.4% (n = 725/4159) of patients, with asthma being the most common (n = 334/4811, 6.9%). This study verified that MrMP patients show more severe initial radiographic findings and clinical courses than MSMP patients. MrMP should be promptly managed by agents other than macrolides.

Genotype and mutation patterns of macrolide resistance genes of Mycoplasma pneumoniae from children with pneumonia in Qingdao, China, in 2019

OBJECTIVES

This study assessed the incidence and resistance of Mycoplasma pneumoniae (MP) in children in Qingdao, China, in 2019.

METHODS

We detected MP infection in 78 pharyngeal swabs from children with pneumonia by qPCR. The RepMP4 element in the P1 adhesin gene, domain V of the 23S rRNA gene, and the L4/L22 ribosomal proteins were amplified by nested PCR. Evolutionary analysis was conducted based on the P1 gene sequence. Resistance mutations in domain V of the 23S rRNA gene and L4/L22 ribosomal proteins were analysed.

RESULTS

The incidence of MP infection in children with pneumonia was 59.0% (46/78). The mean duration of MP infection was longer than that of non-MP infection. According to P1 gene sequencing of 21 samples, 12 (57.1%) were type 1 and 9 (42.9%) were type 2. Drug resistance mutations A2063G in domain V of 23S rRNA gene and T508C in L22 were identified from all sequenced MP. However, mutations at positions 2064 and 2617 were not found in this study. C162A mutation appeared in most type 2 samples. A430G mutation appeared in one type 1 sample and in several type 2 samples. T279C mutation in L22 was mostly found in type 2 samples.

CONCLUSION

The incidence of MP infection was 59.0% in children with pneumonia in Qingdao in 2019. Type 1 MP infection was slightly more common than type 2, indicating that the genotype of MP is gradually shifting from type 1 to type 2. Macrolide resistance mutation A2063G could be detected in all sequenced MP.

The Role of Respiratory Flora in the Pathogenesis of Chronic Respiratory Diseases

Large quantities of bacteria, including Firmicutes, Actinobacteria, and Bacteroidetes, colonize the surface of the respiratory mucosa of healthy people. They interact and coexist with the local mucosal immune system of the human airway, maintaining the immune stability and balance of the respiratory system. While suffering from chronic respiratory diseases, the microbial population in the airway changes and the proportion of Proteobacteria is increased in patients with asthma. The abundance of the microbial population in patients with chronic obstructive pulmonary disease (COPD) is decreased, and conversely, the proportion of Firmicutes and Proteobacteria increased. The diversity of airway microorganisms in cystic fibrosis (CF) patients is decreased, while pathogenic bacteria and conditional pathogenic bacteria are proliferated in large numbers. The proportion of Firmicutes and Proteobacteria is increased in patients with upper airway cough syndrome (UACS), which replaces the dominance of Streptococcus and Neisseria in the pharynx of a normal population. Therefore, a clear understanding of the immune process of the airway flora and the immune dysfunction of the flora on the pathogenesis of chronic respiratory diseases can provide new ideas for the prevention and treatment of human respiratory diseases.

Macrolide resistance and molecular typing of Mycoplasma pneumoniae infections during a 4 year period in Spain

Background

Mycoplasma pneumoniae (MP) causes community-acquired pneumonia affecting mainly children, and tends to produce cyclic outbreaks. The widespread use of macrolides is increasing resistance rates to these antibiotics. Molecular tools can help in diagnosis, typing and resistance detection, leading to better patient management.

Objectives

To assess the MP genotypes and resistance pattern circulating in our area while comparing serological and molecular diagnosis of MP.

Methods

Molecular and serological diagnosis of MP was performed in 821 samples collected in Badalona (Barcelona, Spain) from 2013 to 2017. Multiple locus variable number tandem repeat analysis (MLVA) and macrolide resistance detection by pyrosequencing were performed in those cases positive by PCR. Presence of respiratory viruses and relevant clinical data were also recorded.

Results

MP was detected in 16.8% of cases by PCR, with an overall agreement with serology of 76%. Eleven different MLVA types were identified, with 4-5-7-2 (50.1%) and 3-5-6-2 (29.2%) being the most abundant, with the latter showing a seasonal increase during the study. A total of 8% of the strains harboured a point substitution associated with macrolide resistance, corresponding mainly to an A2063G 23S rRNA mutation and directly related to previous macrolide therapy. Analysis of respiratory viruses showed viral coinfections in most cases.

Conclusions

Serological and molecular tools combined could improve MP diagnosis and the analysis of its infection patterns. Macrolide resistance is associated with previous therapy. Given that MP pneumonia usually resolves spontaneously, it should be reconsidered whether antibiotic treatment is suitable for all cases.

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.

Evaluation of GENECUBE Mycoplasma for the detection of macrolide-resistant Mycoplasma pneumoniae

Introduction. Resistance against macrolide antibiotics in Mycoplasma pneumoniae is becoming non-negligible in terms of both appropriate therapy and diagnostic stewardship. Molecular methods have attractive features for the identification of Mycoplasma pneumoniae as well as its resistance-associated mutations of 23S ribosomal RNA (rRNA).Hypothesis/Gap Statement. The automated molecular diagnostic sytem can identify macrolide-resistant M. pneumoniae.Aim. To assess the performance of an automated molecular diagnostic system, GENECUBE Mycoplasma, in the detection of macrolide resistance-associated mutations.Methodology. To evaluate whether the system can distinguish mutant from wild-type 23S rRNA, synthetic oligonucleotides mimicking known mutations (high-level macrolide resistance, mutation in positions 2063 and 2064; low-level macrolide resistance, mutation in position 2067) were assayed. To evaluate clinical oropharyngeal samples, purified nucleic acids were obtained from M. pneumoniae-positive samples by using the GENECUBE system from nine hospitals. After confirmation by re-evaluation of M. pneumoniae positivity, Sanger-based sequencing of 23S rRNA and mutant typing using GENECUBE Mycoplasma were performed.Results. The system reproducibly identified all synthetic oligonucleotides associated with high-level macrolide resistance. Detection errors were only observed for A2067G (in 2 of the 10 measurements). The point mutation in 23S rRNA was detected in 67 (26.9 %) of 249 confirmed M. pneumoniae-positive clinical samples. The mutations at positions 2063, 2064 and 2617 were observed in 65 (97.0 %), 2 (3.0 %) and 0 (0.0 %) of the 67 samples, respectively. The mutations at positions 2063 and 2064 were A2063G and A2064G, respectively. The results from mutant typing using GENECUBE Mycoplasma were in full agreement with the results from sequence-based typing.Conclusion. GENECUBE Mycoplasma is a reliable test for the identification of clinically significant macrolide-resistant M. pneumoniae.

Benefits and risks of therapeutic alternatives for macrolide resistant Mycoplasma pneumoniae pneumonia in children

Although Mycoplasma pneumoniae pneumonia (MPP) has been generally susceptible to macrolides, the emergence of macrolide-resistant MPP (MRMP) has made its treatment challenging. MRMP rapidly spread after the 2000s, especially in East Asia. MRMP is more common in children and adolescents than in adults, which is likely related to the frequent use of macrolides for treating M. pneumoniae infections in children. MRMP is unlikely to be related to clinical, laboratory, or radiological severity, although it likely prolongs the persistence of symptoms and the length of hospital stay. Thereby, it causes an increased burden of the disease and poor quality of life for the patient as well as a societal socioeconomic burden. To date, the only alternative treatments for MRMP are secondary antimicrobials such as tetracyclines (TCs) or fluoroquinolones (FQs) or systemic corticosteroids; however, the former are contraindicated in children because of concerns about potential adverse events (i.e., tooth discoloration or tendinopathy). A few guidelines recommended TCs or FQs as the second-line drug of choice for treating MRMP. However, there have been no evidence-based guidelines. Furthermore, safety issues have not yet been resolved. Therefore, this article aimed to review the benefits and risks of therapeutic alternatives for treating MRMP in children and review the recommendations of international or regional guidelines and specific considerations for their practical application.

Extra-pulmonary diseases related to Mycoplasma pneumoniae in children: recent insights into the pathogenesis

PURPOSE OF REVIEW

Providing an overview on Mycoplasma pneumoniae-related extra-pulmonary diseases (MpEPDs) in children, who represent the preferred target population by those complications, and discussing the main pathogenic mechanisms implicated or potentially involved.

RECENT FINDINGS

Recent evidences supported the fact that M. pneumoniae is more than an extra-cellular pathogen colonizing epithelial cells of the respiratory tract. It is able to penetrate the cell membrane of host cells and to invade the respiratory mucosa, leading to pronounced inflammatory responses and also spreading outside the respiratory system, to some extent. Thus, direct and indirect (immune-mediated) mechanisms have been described in M. pneumoniae infections, but the latter ones have been mainly implicated in MpEPDs, as reviewed here. Recently, interesting insights have been provided, especially as concern neurologic complications, and new potential mechanisms of disease have been emerging for autoimmunity.

SUMMARY

The awareness of the occurrence of MpEPDs, showing very variable clinical expressions, could promote a correct diagnosis and an appropriate treatment. The knowledge of disease mechanisms in MpEPDs is largely incomplete, but recent advances from clinical studies and murine models might promote and direct future research.

Antimicrobial susceptibility and genotyping of Mycoplasma pneumoniae isolates in Beijing, China, from 2014 to 2016

Background

The presence of macrolide-resistant Myocplasma pneumoniae has been frequently reported in recent years, especially in China. In this study, we investigated the antimicrobial susceptibility and genotype against M. pneumoniae isolates from 2014 to 2016, Beijing.

Methods

We investigated the activities of four antibiotics against 81 M. pneumoniae isolates in vitro. All isolates were amplification of domains II and V of the 23S rRNA gene and the L4 and L22 ribosomal protein fragments. All isolates were genotyped with duplex real-time PCR, MLVA and VNTR detection in p1 gene.

Results

The macrolide resistance rate was 65.4% (53/81). Each of the macrolide-resistant M. pneumoniae isolates was resistant to erythromycin (Minimum Inhibitory Concentration, MIC, ≥256 μg/ml) and azithromycin (MIC, 2-64 μg/ml), but susceptible to tetracycline and levofloxacin in vitro. Fifty two macrolide-resistant isolates harbored the A2063G mutation, and only 1 macrolide-resistant isolates harbored the A2064G mutation in domain V of the 23S ribosomal RNA gene. The C162A, A430G, and T279C mutations in the L4 and L22 ribosomal protein genes were not responsible for macrolide resistance, but they were related to the particular genotype of M. pneumoniae. 95.7% of type 1 isolates (45/47) were macrolide-resistance, and 23.5% of the type 2 isolates (8/34) were macrolide-resistance. Type 2 M. pneumoniae macrolide-resistance rate was 50.6% higher than that of the previous reports in China. The eight macrolide-resistant type 2 M. pneumoniae isolates were belong to 3/5/6/2 and 3/5/7/2 MLVA genotypes.

Conclusion

To our knowledge, this phenomenon likely resulted from a combination of genotype shifting from type1 to type 2 and antibiotic selection pressure in M. pneumoniae in China in recent years. The increase of resistance in type 2 is not due to the spread of same clone. However, the relationship between genotype shifts and macrolide resistance in M. pneumoniae needs to be further verified with more extensive surveillance data.

Comparison of Efficacy of Antimicrobial Agents Among Hospitalized Patients With Mycoplasma pneumoniae Pneumonia in Japan During Large Epidemics of Macrolide-Resistant M. pneumoniae Infections: A Nationwide Observational Study

Background

Mycoplasma pneumoniae strains with resistance to macrolides have been spreading worldwide. Here, we aimed to clarify which antimicrobial agent is a better treatment for patients with M. pneumoniae pneumonia in a setting with large epidemics of macrolide resistance.

Methods

Adult patients hospitalized with laboratory-confirmed M. pneumoniae pneumonia from 2010 to 2013 were identified from the Japanese Diagnosis Procedure Combination national database. Drug switching, length of stay (LOS), 30-day mortality, and total costs for patients who underwent macrolide, quinolone, and tetracycline therapy were compared using propensity score analyses.

Results

Eligible patients (N = 1650) from 602 hospitals were divided into the macrolide group (n = 508), quinolone group (n = 569), or tetracycline group (n = 573). We found that 52.8%, 21.8%, and 38.6% of patients in the macrolide, quinolone, and tetracycline groups, respectively, had to switch drugs (P < .0001). There was no significant difference in the LOS and the 30-day mortality rates among these 3 groups. Cost was highest in the quinolone group (P = .0062). The propensity score-matched pairs (n = 487×2) generated from the quinolone and tetracycline groups also showed a lower proportion of patients who require switches in the quinolone group than in the tetracycline group (21.2% vs 39.6%, P < .0001) but not in the LOS, mortality, and cost.

Conclusions

There were no significant differences in the LOS and mortality among any antimycoplasmal drugs as initial treatment for hospitalized M. pneumoniae pneumonia patients despite the lower switching rate in the quinolone group.

Mycoplasma pneumoniae: A Potentially Severe Infection

Mycoplasma pneumoniae infections remain one of the most common etiologies of community-acquired pneumonia (CAP). The clinical presentation and manifestations vary widely and can affect all organs of the body. Diagnosis is challenging because there are no constant findings in physical exams or laboratory or radiological assessments that indicate Mycoplasma pneumoniae pneumonia, and specific diagnostic tools are not readily available. Extrapulmonary manifestations and severe pulmonary manifestations can lead to long-term sequelae. The increasing emergence of Mycoplasma pneumoniae that is resistant to macrolides in some areas of the world and increased world travel could add to the difficulty of controlling and treating Mycoplasma pneumoniae infections. We present a concise and up-to-date review of the current knowledge of Mycoplasma pneumoniae pneumonia.

Mycoplasma pneumoniae from the Respiratory Tract and Beyond

Mycoplasma pneumoniae is an important cause of respiratory tract infections in children as well as adults that can range in severity from mild to life-threatening. Over the past several years there has been much new information published concerning infections caused by this organism. New molecular-based tests for M. pneumoniae detection are now commercially available in the United States, and advances in molecular typing systems have enhanced understanding of the epidemiology of infections. More strains have had their entire genome sequences published, providing additional insights into pathogenic mechanisms. Clinically significant acquired macrolide resistance has emerged worldwide and is now complicating treatment. In vitro susceptibility testing methods have been standardized, and several new drugs that may be effective against this organism are undergoing development. This review focuses on the many new developments that have occurred over the past several years that enhance our understanding of this microbe, which is among the smallest bacterial pathogens but one of great clinical importance.

Encouraging rational antibiotic use in childhood pneumonia: a focus on Vietnam and the Western Pacific Region

Globally, pneumonia is considered to be the biggest killer of infants and young children (aged <5 years) outside the neonatal period, with the greatest disease burden in low- and middle-income countries. Optimal management of childhood pneumonia is challenging in settings where clinicians have limited information regarding the local pathogen and drug resistance profiles. This frequently results in unnecessary and poorly targeted antibiotic use. Restricting antibiotic use is a global priority, particularly in Asia and the Western Pacific Region where excessive use is driving high rates of antimicrobial resistance. The authors conducted a comprehensive literature review to explore the antibiotic resistance profile of bacteria associated with pneumonia in the Western Pacific Region, with a focus on Vietnam. Current management practices were also considered, along with the diagnostic dilemmas faced by doctors and other factors that increase unnecessary antibiotic use. This review offers some suggestions on how these issues may be addressed.

Therapeutic efficacy of azithromycin, clarithromycin, minocycline and tosufloxacin against macrolide-resistant and macrolide-sensitive Mycoplasma pneumoniae pneumonia in pediatric patients

OBJECTIVE

To clarify therapeutic effects of azithromycin, clarithromycin, minocycline and tosufloxacin against macrolide-resistant Mycoplasma pneumoniae (MRMP) pneumonia and against macrolide-sensitive Mycoplasma pneumoniae (MSMP) pneumonia in pediatric patients.

METHODS

A prospective, multicenter observational study was conducted from July 2013 to August 2015. The therapeutic effects of azithromycin, clarithromycin, minocycline and tosufloxacin were evaluated in 59 patients with pneumonia caused by MRMP and in 50 patients with pneumonia caused by MSMP. In vitro activities of antimicrobial agents against isolates of Mycoplasma pneumoniae were also measured.

RESULTS

Mean durations of fever following commencement of treatment in patients infected with MRMP and MSMP were 5.2 and 1.9 days, respectively (log-rank test, P < 0.0001). Among patients infected with MRMP, mean durations of fever were 4.6, 5.5, 1.0 and 7.5 days for patients treated with azithromycin, clarithromycin, minocycline and tosufloxacin, respectively (log-rank test, P < 0.0001). Among patients infected with MSMP, mean durations of fever were 2.5, 1.7, 0.9 and 4.3 days for patients treated with azithromycin, clarithromycin, minocycline and tosufloxacin, respectively (log-rank test, P = 0.0162). The MIC90s of azithromycin and clarithromycin among the 27 isolates of MRMP were 64 and 256 μg/ml, respectively, and those among the 23 isolates of MSMP were <0.000125 and 0.001 μg/ml, respectively. The MIC90s of minocycline and tosufloxacin among the 27 isolates of MRMP were 1.0 and 0.25 μg/ml, respectively, and those among the 23 isolates of MSMP were 1.0 and 0.5 μg/ml, respectively.

CONCLUSION

Both minocycline and tosufloxacin showed good in vitro activities against MRMP. Minocycline, but not tosufloxacin, shortened the duration of fever in pediatric patients infected with MRMP compared to the duration of fever in patients treated with macrolides.

Mycoplasma pneumoniae: Current Knowledge on Macrolide Resistance and Treatment

Mycoplasma pneumoniae causes community-acquired respiratory tract infections, particularly in school-aged children and young adults. These infections occur both endemically and epidemically worldwide. M. pneumoniae lacks cell wall and is subsequently resistant to beta-lactams and to all antimicrobials targeting the cell wall. This mycoplasma is intrinsically susceptible to macrolides and related antibiotics, to tetracyclines and to fluoroquinolones. Macrolides and related antibiotics are the first-line treatment of M. pneumoniae respiratory tract infections mainly because of their low MIC against the bacteria, their low toxicity and the absence of contraindication in young children. The newer macrolides are now the preferred agents with a 7-to-14 day course of oral clarithromycin or a 5-day course of oral azithromycin for treatment of community-acquired pneumonia due to M. pneumoniae, according to the different guidelines worldwide. However, macrolide resistance has been spreading for 15 years worldwide, with prevalence now ranging between 0 and 15% in Europe and the USA, approximately 30% in Israel and up to 90–100% in Asia. This resistance is associated with point mutations in the peptidyl-transferase loop of the 23S rRNA and leads to high-level resistance to macrolides. Macrolide resistance-associated mutations can be detected using several molecular methods applicable directly from respiratory specimens. Because this resistance has clinical outcomes such as longer duration of fever, cough and hospital stay, alternative antibiotic treatment can be required, including tetracyclines such as doxycycline and minocycline or fluoroquinolones, primarily levofloxacin, during 7–14 days, even though fluoroquinolones and tetracyclines are contraindicated in all children and in children < 8 year-old, respectively. Acquired resistance to tetracyclines and fluoroquinolones has never been reported in M. pneumoniae clinical isolates but reduced susceptibility was reported in in vitro selected mutants. This article focuses on M. pneumoniae antibiotic susceptibility and on the development and the evolution of acquired resistance. Molecular detection of resistant mutants and therapeutic options in case of macrolide resistance will also be assessed.

Infection with and Carriage of Mycoplasma pneumoniae in Children

“Atypical” pneumonia was described as a distinct and mild form of community-acquired pneumonia (CAP) already before Mycoplasma pneumoniae had been discovered and recognized as its cause. M. pneumoniae is detected in CAP patients most frequently among school-aged children from 5 to 15 years of age, with a decline after adolescence and tapering off in adulthood. Detection rates by polymerase chain reaction (PCR) or serology in children with CAP admitted to the hospital amount 4–39%. Although the infection is generally mild and self-limiting, patients of every age can develop severe or extrapulmonary disease. Recent studies indicate that high rates of healthy children carry M. pneumoniae in the upper respiratory tract and that current diagnostic PCR or serology cannot discriminate between M. pneumoniae infection and carriage. Further, symptoms and radiologic features are not specific for M. pneumoniae infection. Thus, patients may be unnecessarily treated with antimicrobials against M. pneumoniae. Macrolides are the first-line antibiotics for this entity in children younger than 8 years of age. Overall macrolides are extensively used worldwide, and this has led to the emergence of macrolide-resistant M. pneumoniae, which may be associated with severe clinical features and more extrapulmonary complications. This review focuses on the characteristics of M. pneumoniae infections in children, and exemplifies that simple clinical decision rules may help identifying children at high risk for CAP due to M. pneumoniae. This may aid physicians in prescribing appropriate first-line antibiotics, since current diagnostic tests for M. pneumoniae infection are not reliably predictive.

Atopy: a risk factor of refractory mycoplasma pneumoniae pneumonia?

OBJECTIVE

To investigate the relationship of pathogen DNA copies with clinic and laboratory features among children with Mycoplasma pneumoniae (MP) pneumonia.

METHODS

A total of 95 enrolled children with MP pneumonia were assigned into the high-MP-load group (>10⁶ /mL) and the low-MP-load group (≤10⁶ /mL) according to MP-DNA copies in bronchoalveolar lavage fluid (BALF). Clinical characteristics and any allergy history were collected. Aeroallergens and food allergens were detected with a skin test. Serum IgE and eosinophil cationic protein (ECP) were assessed using enzyme immunoassay. BALF levels of IL-4, IFN-γ, IL-8 and TNF-α were assessed by ELISA.

RESULTS

Compared with the low-MP-load group, 72.7% in the high-MP-load group developed refractory MP pneumonia who failed to respond to at least 1-week treatment with macrolides (72.7% vs 41.9%, P = 0.005). More children in the high-load group than those in the low-load group presented with extrapulmonary manifestations, lung consolidation, pleural effusion and atopic conditions including any allergy history, positive findings of aeroallergen test and increased serum IgE and ECP (P < 0.05). A significant higher BALF IL-4 level was seen in the high-load group versus the low-load group (23.00 ± 11.24 vs 14.68 ± 7.12; pg/mL; P < 0.01). There were no significant differences in BALF levels of IFN-γ, IL-8 and TNF-α between the two groups (P > 0.05).

CONCLUSION

Atopy may be a risk factor for the presence and severity of refractory MP pneumonia due to the high pathogen load in airway.

Th1/Th2 Cytokine Profile and Its Diagnostic Value in Mycoplasma pneumoniae Pneumonia

BACKGROUND

The levels of Th1/Th2 cytokine can alter in pathogenic infection in children with pneumonia.

OBJECTIVES

To evaluate Th1/Th2 cytokine profile and its diagnostic value in M. pneumoniae pneumonia in children.

PATIENTS AND METHODS

Children with M. pneumoniae mono-infection and 30 healthy children were tested with cytokines assay. We used real time PCR to detect M. pneumoniae in children with pneumonia.

RESULTS

M. pneumoniae test was positive in 2188 (16.62%) out of 13161 pneumonia children. Children aged 5 - 9 years had the highest rate and summer was a season with high rate of M. pneumoniae incidence in Zhejiang province. During the course of study, in 526 pneumonia children with M. pneumoniae mono-infection and 30 healthy children cytokines assay was performed. IL-2 level of M. pneumoniae pneumonia children was lower than that of healthy children (median levels, pg/mL: IL-2: 3.2 vs. 5.7, P = 0.00), while IL-4, IL-10 and IFN-γ were higher than in healthy children (median levels, pg/mL: IL-4: 3.2 vs. 1.5, P = 0.00; IL-10: 5.6 vs. 2.5, P = 0.001; IFN-γ: 20.4 vs. 4.8, P = 0.001).

CONCLUSIONS

IL-2 decreases and IL-4, IL-10 and IFN-γ increase in children with M. pneumoniae pneumonia, which has a promising prospect in diagnosis of this disease in clinical practice.

Classification of Extrapulmonary Manifestations Due to Mycoplasma pneumoniae Infection on the Basis of Possible Pathogenesis

The list of extrapulmonary manifestations due to Mycoplasma pneumoniae infection can be classified according to the following three possible mechanisms derived from the established biological activity of M. pneumoniae; (1) a direct type in which the bacterium is present at the site of inflammation and local inflammatory cytokines induced by the bacterium play an important role (2) an indirect type in which the bacterium is not present at the site of inflammation and immune modulations, such as autoimmunity or formation of immune complexes, play an important role, and (3) a vascular occlusion type in which obstruction of blood flow induced either directly or indirectly by the bacterium plays an important role. Recent studies concerning extrapulmonary manifestations have prompted the author to upgrade the list, including cardiac and aortic thrombi as cardiovascular manifestations; erythema nodosum, cutaneous leukocytoclastic vasculitis, and subcorneal pustular dermatosis as dermatological manifestations; acute cerebellar ataxia, opsoclonus-myoclonus syndrome, and thalamic necrosis as neurological manifestations; pulmonary embolism as a respiratory system manifestation; and renal artery embolism as a urogenital tract manifestation. Continuing nosological confusion on M. pneumoniae–induced mucositis (without skin lesions), which may be called M. pneumoniae-associated mucositis or M. pneumoniae-induced rash and mucositis separately from Stevens-Johnson syndrome, is argued in the dermatological manifestations. Serological methods are recommended for diagnosis because pneumonia or respiratory symptoms are often minimal or even absent in extrapulmonary manifestations due to M. pneumoniae infection. Concomitant use of immunomodulators, such as corticosteroids or immunoglobulins with antibiotics effective against M. pneumoniae, can be considered as treatment modalities for most severe cases, such as encephalitis. Further studies would be necessary to construct a comprehensive therapeutic strategy, covering microbiology (antibiotics), immunology (immunomodulators), and hematology (anticoagulants). The possible influence of the emergence of macrolide-resistant M. pneumoniae on extrapulmonary manifestations, which can be considered of limited clinical threat in Japan where the resistant rate has currently decreased, is discussed on the basis of unique biological characteristics of M. pneumoniae, the smallest self-replicating organism.

Regional Differences in Prevalence of Macrolide Resistance among Pediatric Mycoplasma pneumoniae Infections in Hokkaido, Japan

Recently, macrolide-resistant (MR) Mycoplasma pneumonia appeared, and prevalence of macrolide resistance among M. pneumoniae infections varies by country. However, reports on regional differences in the prevalence of MR M. pneumonia within a country are scarce. In this study, 617 nasopharyngeal swab samples were collected from 617 pediatric patients, and DNA of M. pneumoniae was identified in 95 samples. In 51 of the 95 M. pneumonia positive samples, we detected the presence of mutation A2063G mutation (conferring macrolide resistance) in the 23S rRNA gene. The overall macrolide resistance rate was 53.7%, but there were regional differences: 0.0% in Muroran, 5.3% in Asahikawa, 55.3% in Sapporo, and 100.0% in Kushiro. Statistically significant pairwise differences in the prevalence of MR M. pneumoniae were observed among these cities except for the pair of Muroran and Asahikawa. After exclusion (in order to avoid the influence of macrolides) of patients who were prescribed macrolides before collection of nasopharyngeal swab samples, statistically significant differences persisted: 0.0% in Muroran, 5.6% in Asahikawa, 38.5% in Sapporo, and 100.0% in Kushiro.

Mycoplasma pneumoniae infections--does treatment help?

Mycoplasma pneumoniae is a common cause of respiratory tract infections (RTI's), especially in children. While severe M. pneumoniae infections are generally treated with antibiotics, the diagnosis as well as treatment of these infections should be reconsidered in the light of recent clinical findings. First, M. pneumoniae was found to be carried in the upper respiratory tract of a relatively high percentage of healthy, asymptomatic children. Clearly, this complicates the diagnosis of a suspected M. pneumoniae RTI and, thus, the decision when to initiate treatment. A complication in the treatment of these infections is that data on the efficacy of antibiotic treatment of M. pneumoniae RTI's are sparse and derived exclusively from comparative studies. A recent Cochrane review concluded that there is insufficient evidence about the efficacy of antibiotics for M. pneumoniae lower respiratory tract infections (LRTI) in children. Due to side effects associated with the use of tetracyclines and quinolones in children, only macrolides can be used to treat M. pneumoniae infections in young patients. The general applicability of macrolides, however, is currently threatened by the worldwide increase in macrolide-resistant M. pneumoniae strains. Finally, limited evidence is available that corticosteroids might have an additional benefit in the treatment of M. pneumoniae infections. In this review, the current issues related to the diagnosis and treatment of M. pneumoniae infections will be discussed.

Pregnant women infected with pandemic H1N1pdm2009 influenza virus displayed overproduction of peripheral blood CD69+ lymphocytes and increased levels of serum cytokines

The first pandemic of the 21^st century occurred in 2009 and was caused by the H1N1pdm influenza A virus. Severe cases of H1N1pdm infection in adults are characterized by sustained immune activation, whereas pregnant women are prone to more severe forms of influenza, with increased morbi-mortality. During the H1N1pdm09 pandemic, few studies assessed the immune status of infected pregnant women. The objective of this study was to evaluate the behavior of several immune markers in 13 H1N1pdm2009 virus-infected pregnant (PH1N1) women, in comparison to pregnant women with an influenza-like illness (ILI), healthy pregnant women (HP) and healthy non-pregnant women (HW). The blood leukocyte phenotypes and the serological cytokine and chemokine concentrations of the blood leukocytes, as measured by flow cytometry, showed that the CD69+ cell counts in the T and B-lymphocytes were significantly higher in the PH1N1 group. We found that pro-inflammatory (TNF-α, IL-1β, IL-6) and anti-inflammatory (IL-10) cytokines and some chemokines (CXCL8, CXCL10), which are typically at lower levels during pregnancy, were substantially increased in the women in the ILI group. Our findings suggest that CD69 overexpression in blood lymphocytes and elevated levels of serum cytokines might be potential markers for the discrimination of H1N1 disease from other influenza-like illnesses in pregnant women.

Novel aspects on the pathogenesis of Mycoplasma pneumoniae pneumonia and therapeutic implications

Mycoplasma pneumoniae (Mp) is a leading cause of community acquired pneumonia. Knowledge regarding Mp pneumonia obtained from animal models or human subjects has been discussed in many different reports. Accumulated expertise concerning this critical issue has been hard to apply clinically, and potential problems may remain undiscovered. Therefore, our multidisciplinary team extensively reviewed the literature regarding Mp pneumonia, and compared findings from animal models with those from human subjects. In human beings, the characteristic pathological features of Mp pneumonia have been reported as alveolar infiltration with neutrophils and lymphocytes and lymphocyte/plasma cell infiltrates in the peri-bronchovascular area. Herein, we demonstrated the novel aspects of Mp pneumonia that the severity of the Mp pneumonia seemed to depend on the host innate immunity to the Mp, which might be accelerated by antecedent Mp exposure (re-exposure or latent respiratory infection) through up-regulation of Toll-like receptor 2 expression on bronchial epithelial cells and alveolar macrophages. The macrolides therapy might be beneficial for the patients with macrolide-resistant Mp pneumonia via not bacteriological but immunomodulative effects. This exhaustive review focuses on pathogenesis and extends to some therapeutic implications such as clarithromycin, and discusses the various diverse aspects of Mp pneumonia. It is our hope that this might lead to new insights into this common respiratory disease.