OBJECTIVE: To study the drug resistance of METHODS: BALF specimens were collected from 245 children with RMPP who were admitted to the Children's Hospital Affiliated to Zhengzhou University from March 2016 to December 2020. A rapid cultured drug sensitivity assay was used to detect the resistance of MP isolates to nine commonly used antimicrobial drugs. The real-time PCR was used to measure MP DNA. The direct sequencing was used to detect gene mutations in MP 23SrRNA V region central ring. RESULTS: Among the 245 BALF specimens, 207 tested positive for MP DNA, with a positive rate of 84.5%. The results of drug susceptibility test showed that the children with RMPP had a resistance rate of > 70% to macrolide antimicrobial drugs, with the highest resistance rate to clarithromycin, followed by roxithromycin, clindamycin, acetylspiramycin, erythromycin, and azithromycin, and these children had a resistance rate of < 5% to quinolone antimicrobial drugs. Among the 207 MP DNA-positive specimens, 41 (19.8%) had no drug-resistance gene mutations and 166 (80.2%) had drug-resistance gene mutations, among which 154 (74.4%) had an A→G mutation at 2063 locus of 23SrRNA V region central ring, 7 (3.4%) had an A→G mutation at 2064 locus, and 5 (2.4%) had mutations in both 2063 and 2064 loci. Among the 166 specimens with point mutations of the MP 23SrRNA gene, 159 (95.8%) had point mutations at 2063 locus. The A→G point mutation at 2063 locus of 23SrRNA V region central ring had a great impact on resistance to macrolide antimicrobial drugs. There was a significant difference in the distribution of alleles at 2063 locus between the children with resistance to clarithromycin, roxithromycin, clindamycin, acetylspiramycin, erythromycin, and azithromycin ( CONCLUSIONS MP in the BALF of children with RMPP has a relatively high resistance rate to macrolide antimicrobial drugs. Resistance to macrolide antimicrobial drugs is closely associated with the A→G point mutation in the 23SrRNA gene, and the point mutation at 2063 locus of 23SrRNA V region central ring may affect the drug-resistance mechanism of MP.
Anti-Bacterial Agents/pharmacology* ; Bronchoalveolar Lavage Fluid ; Child ; Drug Resistance, Bacterial/genetics* ; Humans ; Mycoplasma pneumoniae/genetics* ; Pneumonia, Mycoplasma/drug therapy*

OBJECTIVEThe P1 protein of Mycoplasma pneumoniae (MP) plays an important role in the pathogenesis of MP pneumonia. It mediates the attachment of the pathogen to host cells and elicits a strong humoral immune response during infection. In early studies, only two types of MP P1 genes were assumed to exist. Later, eight subtypes of MP P1 genes and some variations of P1 gene were reported. However, there are no related reports in China until now. This study aimed to understand epidemiology of MP subtype in Zhejiang province, China, as well as the relationship between MP subtype and clinical severity of MP pneumonia.

METHODClinical samples were collected by nasopharyngeal aspiration from children with MP pneumonia hospitalized in the Children's Hospital of Zhejiang University School of Medicine from February to December in 2009. P1 gene fragment was amplified by using PCR method (with primers of ADH1/ADH2 and ADH3/ADH4, respectively). Then ADH1/ADH2-generated fragments were digested with HaeIII, HpaII, Sau3A, and the ADH3/ADH4-generated fragments digested with HaeIII, Sau3A, HhaI, RsaI. The MP P1 subtypes were determined based on resulting fragments. Part of samples were selected for sequencing. The clinical data of different MP subtype pneumonia were compared.

RESULTA total of 300 hospitalized children with MP pneumonia were enrolled in this study. All the samples produced specific bands for MP P1 gene after PCR with primers of ADH1/ADH2 and ADH3/ADH4 respectively. By restrictive fragment length polymorphism analysis, 297 clinical specimens showed the characteristic band patterns for P1 type 1 identical to Mp129, and only 3 clinical specimens showed the characteristic band pattern for P1 type 2 identical to MP-FH. All P1 type 1 and P1 type 2 showed the same subtype bands respectively, as subtype 1b and 2a. After sequencing, one synonymous point mutation in P1 type 1 was identified relative to the MP129 P1 sequence at nucleotide position (nt) 208(G→A). Three cases with P1 type 2 MP pneumonia were found to have liver damage, and longer hospital stay and fever duration than P1 type 1, but no statistically significant difference was found.

CONCLUSIONClinical samples can be used directly for genotyping of MP. The dominating type of MP in Zhejiang Province was P1 type 1 subtype 1b. But whether there was any relationship between MP subtype and clinical severity remains to be clarified.

Adhesins, Bacterial ; genetics ; Child ; China ; DNA, Bacterial ; genetics ; Genotype ; Humans ; Mycoplasma pneumoniae ; genetics ; isolation & purification ; Nasopharynx ; microbiology ; Pneumonia, Mycoplasma ; microbiology ; Polymorphism, Restriction Fragment Length

OBJECTIVETo investigate the association of drug resistance of Mycoplasma pneumoniae (MP) with DNA load and genotypes in children with MP pneumonia.

METHODSA total of 230 children who were hospitalized and diagnosed with MP pneumonia between January 2012 and December 2016 were enrolled. Throat swabs were collected from the 230 children, and a rapid drug sensitivity assay was used to determine the sensitivity of clinical isolates of MP to nine commonly used antibacterial agents. Quantitative real-time PCR was used to measure MP-DNA load in throat swabs. PCR sequencing was used to determine the genotype of 2063 locus of the MP 23S rRNA V domain.

RESULTSOf the 230 children, 86 (37.4%) had genotype A in 2063 locus, 134 (58.3%) had genotype G, 8 (3.5%) had genotype C, and 2 (0.9%) had genotype T. Mutant strains (genotype G+C+T) had a significantly higher MP-DNA load than wild-type strains (genotype A) (P<0.05). The strains resistant to erythromycin, azithromycin, clarithromycin, and clindamycin had a significantly higher MP-DNA load than non-resistant strains (P<0.05). MP had a high drug resistance rate to macrolide antibiotics. More than 60% of the cases with resistance to macrolides were found to have A2063G mutations. MP was rarely resistant to quinolones (less than 2%).

CONCLUSIONSMutations in 2063 locus of the MP 23S rRNA V domain may result in the resistance of MP to macrolides and the change in DNA load and can be used as a basis for selecting drugs for MP.

Child ; Child, Preschool ; DNA, Bacterial ; analysis ; Drug Resistance, Bacterial ; Female ; Genotype ; Humans ; Infant ; Male ; Mycoplasma pneumoniae ; drug effects ; genetics ; Pneumonia, Mycoplasma ; drug therapy ; microbiology

OBJECTIVETo investigate the infection rate and genotypes of Mycoplasma pneumoniae (MP) by examining bronchoalveolar lavage fluid from children with community acquired pneumonia (CAP).

METHODSPolymerase chain reaction (PCR) was used for detecting MP in bronchoalveolar lavage fluid from 220 children hospitalized with CAP, and the accuracy was confirmed by quantitative real-time PCR. Positive samples were digested with HaeⅡ and Hae Ⅲ and compared with standard strain to analyze the genotypes of MP from positive samples. The accuracy of genotyping was confirmed by sequencing the amplified products of some randomly selected positive samples.

RESULTSThe positive rate of MP in 220 samples was 55.0% (121/220). MP infection occurred mostly in preschool and school-age children (63.5%, 101/159), and the lowest positive rate was seen in children aged under 6 months (20%, 1/5). The positive rate showed no significant differences between sexes and between seasons. Sixty randomly selected MP-positive samples showed a genotype of P1 type 1 after restriction digestion, which was further confirmed by sequencing of 4 samples.

CONCLUSIONSMP is one of the main pathogens of pneumonia in children, and the MP infection rate is significantly correlated with age. The dominant genotype of MP in children is P1 type 1.

Adolescent ; Child ; Child, Preschool ; Female ; Genotype ; Hospitalization ; Humans ; Infant ; Male ; Mycoplasma pneumoniae ; classification ; genetics ; Phylogeny ; Pneumonia, Mycoplasma ; microbiology ; Real-Time Polymerase Chain Reaction ; Seasons

OBJECTIVEMycoplasma pneumoniae (Mp) infection is one of major causes of community-acquired pneumonia. Isolation and culture of Mp are very difficult, fluorescent quantitative PCR is a new technique to detect Mp. The aim of this study was to explore the diagnostic value of fluorescent quantitation PCR for Mp infection.

METHODMp-DNA from the deep respiratory tract secretion of children suffering from pneumonia was tested by a fluorescent quantitative PCR. Totally 256 cases who were positive for Mp DNA were enrolled into this study, 164 (64.1%) were male, 92 (35.9%) were female; the age ranged from 9 days to 16 years. All the patients also had results of Mp-IgM test. These patients were divided into 2 groups according to the result of Mp-IgM detection, namely, Mp-IgM positive and negative groups. Area under the roc curve (Az) was used as the index to evaluate the diagnostic value of fluorescent quantitation PCR for Mp detection. The number of Mp-DNA copies, age and course of disease of the 2 groups were also compared.

RESULTS(1) Diagnostic accuracy of fluorescent quantitative PCR for detecting Mp infection was that Az = 0.641. (2) The number of copies of the cases in Mp-IgM positive group was 5.42 +/- 1.26 [log(Mp-DNA copy/ml)], while that of Mp-IgM-negative group was 4.87 +/- 1.29 [log(Mp-DNA copy/ml), t = 3.43, P < 0.05]. (3) The age of Mp-IgM positive group was dramatically younger than Mp-IgM negative group (P < 0.001).

CONCLUSIONThe diagnostic accuracy of fluorescent quantitative PCR for mycoplasma pneumoniae (Mp) infection is low; however for children whose immunologic systems are not fully developed, this technique has some diagnostic value, and higher number of Mp-DNA copies may support diagnosis of Mp infection.

Adolescent ; Child ; Child, Preschool ; Female ; Humans ; Immunoglobulin M ; blood ; Infant ; Infant, Newborn ; Male ; Mycoplasma pneumoniae ; genetics ; immunology ; isolation & purification ; Pneumonia, Mycoplasma ; diagnosis ; Polymerase Chain Reaction ; methods

OBJECTIVETo establish and evaluate a real-time PCR assay to detect Mycoplasma pneumoniae (M.pneumoniae) in clinical specimens.

METHODSBy analysing the whole p1 gene sequence of 60 M.pneumoniae clinical isolates in Beijing of China, an optimized real-time PCR assay (MpP1) using p1 gene conserved region was designed. The specificity and sensitivity of this assay were evaluated and compared with other two reported assays (RepMp1 and Mp181) using 40 positive and 100 negative clinical specimens.

RESULTSThe detection limit of the new assay was 8.1 fg (about 1∼3CFU) M.pneumoniae DNA. The sensitivity of MpP1, RepMp1, and Mp181 assays appeared to be 100%, 100%, and 85%, respectively.

CONCLUSIONMpP1 assay is suitable for the detection of M.pneumoniae in Chinese clinical specimens.

Genes, Bacterial ; Humans ; Mycoplasma pneumoniae ; genetics ; isolation & purification ; Real-Time Polymerase Chain Reaction ; Sensitivity and Specificity ; Sequence Analysis, DNA

OBJECTIVEMutations in 23S rRNA gene are known to be associated with macrolide resistance in Mycoplasma pneumoniae (M. pneumoniae). However, these mutations alone do not fully explain the high resistance rates in Asia. The aim of this study was to investigate other possible mutations involved in macrolide resistance in M. pneumoniae.

METHODSThe whole genomes of 10 clinical isolates of M. pneumoniae with macrolide resistance were sequenced by Illumina HiSeq2000 platform. The role of the macrolide-specific efflux transporter was assessed by efflux-pump inhibition assays with reserpine and carbonyl cyanide m-chlorophenyl-hydrazone (CCCP).

RESULTSA total of 56 single nucleotide polymorphisms (SNPs) were identified in 10 clinical isolates in comparison to the reference strains M129 and FH. Strikingly, 4 of 30 SNPs causing non-synonymous mutations were clustered in macrolide-specific efflux system gene macB encoding macrolide-specific efflux pump protein of the ATP-binding cassette transporter family. In assays of the minimal inhibitory concentrations (MIC) of macrolide antibiotics in the presence of the efflux pump inhibitors caused a significant decrease of MICs, even under detectable levels in some strains.

CONCLUSIONOur study suggests that macrolide efflux pump may contribute to macrolide resistance in M. pneumoniae in addition to the common point mutations in 23S rRNA gene.

Anti-Bacterial Agents ; pharmacology ; Drug Resistance, Bacterial ; genetics ; Genome-Wide Association Study ; Macrolides ; pharmacology ; Microbial Sensitivity Tests ; Mutation ; Mycoplasma pneumoniae ; drug effects ; genetics

BACKGROUNDMycoplasma pneumoniae (M. pneumoniae) is one of the common pathogens causing atypical pneumonia. In recent years, resistance to macrolides has become more common, especially in China. Previous studies have confirmed that the mutation at position 2063 in domain V of the 23S rRNA is the most prevalent, followed by the mutation at position 2064. Reported molecular detection methods for the identification of these mutations include direct sequencing, restriction fragment length polymorphism analysis, real-time polymerase chain reaction (PCR) with high-resolution melt analysis, and nested PCR-linked with capillary electrophoresis, etc. The most commonly used method for monitoring resistance-conferring mutations in M. pneumoniae is direct DNA sequencing of PCR or nested PCR products. However, these methods are time-consuming, labor-intensive or need expensive equipments. Therefore the development of rapid and sensitive methods is very important for monitoring the resistance globally.

METHODSIn this study, we reported a fast and cost-effective method for detecting 2063 and/or 2064 macrolide resistant mutations from specimens using a modified allele-specific PCR analysis, and all results were compared with the sequencing data. We also analyzed the clinical courses of these samples to confirm the modified allele-specific PCR results.

RESULTSAmong 97 M. pneumoniae specimens, 88 were found to possess mutations by this method, and all modified allele-specific PCR analysis results were consistent with the sequencing data. The data of the clinical courses of these 97 cases showed that they suffered from severe pneumonia. Erythromycin showed better efficacy on cases from which no macrolide resistance mutation was found on their specimens. However, in some cases from which mutations were detected, erythromycin monotherapy had poor efficacy, and on these patients severe symptoms improved only when azithromycin was added to the treatment.

CONCLUSIONSThe drug-resistant M. pneumoniae is very common in Beijing, China. Our modified allele-specific PCR analysis can identify erythromycin resistant mutations more rapidly from specimens than any other method currently available. Erythromycin is still effective for treating patients infected with the mutation negative M. pneumoniae, but this treatment fails to work on mutant organisms. This method can facilitate clinicians in selecting appropriate therapy within short timescales.

Alleles ; Anti-Bacterial Agents ; pharmacology ; China ; Drug Resistance, Bacterial ; genetics ; Erythromycin ; pharmacology ; Mycoplasma pneumoniae ; drug effects ; genetics ; Polymerase Chain Reaction ; methods

OBJECTIVEMycoplasma pneumoniae (MP) is an important pathogen for community-acquired pneumonia in children. MP infection was considered to be self-limited, but many severe refractory MP pneumonia cases have been reported in recent years. The reason for variation in severity of MP pneumonia remains unclear. MP virulence including drug-resistance and host immunologic function are important influencing factors. The present study aimed to clarify relationship between local MP load and severity of MP pneumonia.

METHODMP DNA was quantitatively detected by fluorescent real-time PCR in bronchoalveolar lavage fluid (BALF) from 77 children with MP pneumonia. They were classified into groups of low MP load ( < 10(3)/ml, n = 14) , moderate MP load (10(3)-10(6)/ml, n = 22) and high MP load ( > 10(6)/ml, n = 41) . Clinical symptoms, main laboratory and imaging results of children among the three groups were compared.

RESULTWhen compared with low load group and moderate load group, high load group had longer fever duration (7 d, 10 d vs. 12 d) , longer time to normalization of temperature with macrolide administration (4 d, 8 d vs. 10 d) , more patients with high fever (50.0%, 68.2% vs. 87.8%) and longer duration of fever than 10 d (35.7%, 50.0% vs. 73.2%).Statistically significant difference existed in CRP among the three groups (1.0 mg/L, 11.5 mg/L, 34 mg/L). Large field of consolidation or atelectasis were found in 58.5% of high load patients, much higher than 22.7% in moderate load and 14.3% in low load patients. Bilateral or massive pleural effusion was not found in low load group, while in moderate load and high load group, they were 13.6% and 24.4%. However, no significant difference was found in symptoms and main laboratory and imaging results among different age groups in high load patients.

CONCLUSIONThere is a close relationship between MP load in BALF and clinical characteristics in children with MP pneumonia. Those with high MP load have a more severe process.

Adolescent ; Bacterial Load ; Bronchoalveolar Lavage Fluid ; microbiology ; Child ; Child, Preschool ; Colony Count, Microbial ; DNA, Bacterial ; genetics ; Female ; Humans ; Infant ; Male ; Mycoplasma pneumoniae ; genetics ; isolation & purification ; Pneumonia, Mycoplasma ; microbiology ; pathology ; Real-Time Polymerase Chain Reaction ; Severity of Illness Index

Amino Acid Sequence ; Animals ; Bacterial Proteins ; genetics ; metabolism ; Bacterial Toxins ; genetics ; metabolism ; Base Sequence ; Community-Acquired Infections ; microbiology ; Gene Expression Regulation, Bacterial ; Humans ; Lung ; microbiology ; pathology ; Mycoplasma pneumoniae ; Pneumonia, Mycoplasma ; microbiology ; Respiratory Distress Syndrome, Adult ; microbiology