[Detection of drug-resistance genes of Mycoplasma pneumoniae in bronchoalveolar lavage fluid of children with refractory Mycoplasma pneumoniae pneumonia]

OBJECTIVE

To study the drug resistance of Mycoplasma pneumoniae (MP) in the bronchoalveolar lavage fluid (BALF) of children with refractory Mycoplasma pneumoniae pneumonia (RMPP) and the distribution of drug-resistance genes, as well as the association of alleles at 2063 locus of 23SrRNA V region central ring with resistance to antimicrobial drugs.

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 (P < 0.05).

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.

[Detection of drug-resistance genes of Mycoplasma pneumoniae in bronchoalveolar lavage fluid of children with refractory Mycoplasma pneumoniae pneumonia]

OBJECTIVE

To study the drug resistance of Mycoplasma pneumoniae (MP) in the bronchoalveolar lavage fluid (BALF) of children with refractory Mycoplasma pneumoniae pneumonia (RMPP) and the distribution of drug-resistance genes, as well as the association of alleles at 2063 locus of 23SrRNA V region central ring with resistance to antimicrobial drugs.

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 (P < 0.05).

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.

[Value of chitinase-like protein YKL-40 in bronchoalveolar lavage fluid for predicting refractory Mycoplasma pneumoniae pneumonia in children]

OBJECTIVE

To evaluate the value of chitinase-like protein YKL-40 in bronchoalveolar lavage fluid (BALF) for predicting refractory Mycoplasma pneumoniae pneumonia (RMPP) in children.

METHODS

A total of 50 children with common Mycoplasma pneumoniae pneumonia (MPP) and 22 children with RMPP were enrolled. The two groups were compared in terms of clinical features, laboratory examination results, imaging findings, and YKL-40 levels in BALF. The receiver operating characteristic (ROC) curve was used to evaluate the value of YKL-40 in BALF for predicting RMPP.

RESULTS

Compared with the common MPP group, the RMPP group had significantly higher incidence rates of fever, shortness of breath, lung consolidation, and pleural effusion (P < 0.05) and significantly higher serum levels of C-reactive protein and lactate dehydrogenase (P < 0.05). The RMPP group had a significantly higher level of YKL-40 in BALF than the common MPP group (P < 0.05). The ROC curve plotted based on the level of YKL-40 in BALF had an area under the ROC curve of 0.750, a sensitivity of 72.7% and a specificity of 64.0% for predicting RMPP.

CONCLUSIONS

There is an increase in the level of YKL-40 in BALF in children with RMPP, and the level of YKL-40 in BALF has a certain value for predicting RMPP.

[Association of YKL-40 in bronchoalveolar lavage fluid with airway damage in children with Mycoplasma pneumoniae pneumonia]

OBJECTIVE

To investigate the association of YKL-40 in bronchoalveolar lavage fluid (BALF) with airway damage in children with Mycoplasma pneumoniae pneumonia (MPP).

METHODS

A total of 60 children with MPP who were admitted to the hospital were enrolled as the MPP group, and 12 children with bronchial foreign bodies were enrolled as the control group. According to the imaging findings, the MPP group was further divided into 3 subgroups: pulmonary patchy shadow (n=34), pulmonary consolidation (n=19) and pulmonary ground-glass opacity (n=7). According to the bronchoscopic findings, the MPP group was further divided into 3 subgroups: mucosal congestion/edema (n=38), mucous secretion (n=18) and plastic bronchitis (n=4). The clinical manifestations and laboratory characteristics of the children with MPP were analyzed, the expression of YKL-40 in BALF was measured.

RESULTS

The MPP group had significantly higher levels of serum lactate dehydrogenase and BALF YKL-40 than the control group (P<0.05). The pulmonary consolidation subgroup had significantly higher levels of serum C-reactive protein and lactate dehydrogenase than the pulmonary patchy shadow subgroup (P<0.05), and the pulmonary consolidation and pulmonary ground-glass opacity subgroups had a significantly higher level of BALF YKL-40 than the pulmonary patchy shadow subgroup (P<0.05). The plastic bronchitis subgroup had a significantly higher level of BALF YKL-40 than the mucous secretion and mucosal congestion/edema subgroups (P<0.05). The mucous secretion and plastic bronchitis subgroups had a significantly higher proportion of children with shortness of breath than the mucosal congestion/edema subgroup (P<0.05). The plastic bronchitis subgroup had significantly higher serum levels of C-reactive protein and lactate dehydrogenase than the mucosal congestion/edema subgroup (P<0.05).

CONCLUSIONS

The level of BALF YKL-40 is associated with airway damage and disease severity in children with MPP.

[Pathogens in bronchoalveolar lavage fluid of children with lower respiratory tract infection]

OBJECTIVE

To study the features of pathogens in children with lower respiratory tract infection.

METHODS

A total of 108 children who were hospitalized due to lower respiratory tract infection and underwent fiber bronchoscopy between January 2017 and June 2018 were enrolled. Bronchoalveolar lavage fluid samples were collected. Multiple quantitative real-time PCR was performed to detect pathogens.

RESULTS

Of the108 children, 85 (78.7%) were found to have pathogens, among whom 52 (48.1%) had single pathogen infection and 33 (30.6%) had multiple pathogen infections. Mycoplasma pneumoniae was detected in 38 children (35.2%), and was the most common pathogen. The children aged 36 - <72 months had the highest detection rate of Mycoplasma pneumoniae. Both Streptococcus pneumoniae and Haemophilus influenzae were detected in 29 children (26.9%) and Streptococcus pneumoniae was mainly detected in children aged <24 months. Each of Acinetobacter baumannii, Candida albicans and Klebsiella pneumoniae was detected in 3 children. Among the 31 children with bronchopneumonia, 9 were found to have Haemophilus influenza, with the highest detection rate of 29%. Among the 34 children with lobar pneumonia, 22 were found to have Mycoplasma pneumoniae, with the highest detection rate of 65%. Among the 22 children with bronchial foreign bodies and bronchopneumonia, 10 were found to have Streptococcus pneumoniae, with the highest detection rate of 45%.

CONCLUSIONS

In children with lower respiratory tract infection, Mycoplasma pneumoniae is the most common pathogen, followed by Streptococcus pneumoniae and Haemophilus influenzae. There are differences in the detection rates of pathogens between children with different ages and different types of lower respiratory tract infection.

[Pathogens in bronchoalveolar lavage fluid of children with lower respiratory tract infection]

OBJECTIVE

To study the features of pathogens in children with lower respiratory tract infection.

METHODS

A total of 108 children who were hospitalized due to lower respiratory tract infection and underwent fiber bronchoscopy between January 2017 and June 2018 were enrolled. Bronchoalveolar lavage fluid samples were collected. Multiple quantitative real-time PCR was performed to detect pathogens.

RESULTS

Of the108 children, 85 (78.7%) were found to have pathogens, among whom 52 (48.1%) had single pathogen infection and 33 (30.6%) had multiple pathogen infections. Mycoplasma pneumoniae was detected in 38 children (35.2%), and was the most common pathogen. The children aged 36 - <72 months had the highest detection rate of Mycoplasma pneumoniae. Both Streptococcus pneumoniae and Haemophilus influenzae were detected in 29 children (26.9%) and Streptococcus pneumoniae was mainly detected in children aged <24 months. Each of Acinetobacter baumannii, Candida albicans and Klebsiella pneumoniae was detected in 3 children. Among the 31 children with bronchopneumonia, 9 were found to have Haemophilus influenza, with the highest detection rate of 29%. Among the 34 children with lobar pneumonia, 22 were found to have Mycoplasma pneumoniae, with the highest detection rate of 65%. Among the 22 children with bronchial foreign bodies and bronchopneumonia, 10 were found to have Streptococcus pneumoniae, with the highest detection rate of 45%.

CONCLUSIONS

In children with lower respiratory tract infection, Mycoplasma pneumoniae is the most common pathogen, followed by Streptococcus pneumoniae and Haemophilus influenzae. There are differences in the detection rates of pathogens between children with different ages and different types of lower respiratory tract infection.

[Levels of surfactant proteins A and D in bronchoalveolar lavage fluid of children with pneumonia and their relationships with clinical characteristics]

OBJECTIVE

To observe the levels of pulmonary surfactant proteins A and D (SP-A, SP-D) in bronchoalveolar lavage fluid (BALF) of children with pneumonia, and to explore their relationships with clinical characteristics.

METHODS

Thirty-five children with pneumonia were enrolled in this study. Differential cell counts were obtained by Countstar counting board. The levels of SP-A and SP-D in BALF were detected using ELISA.

RESULTS

In children with pneumonia, SP-D levels were significantly higher than SP-A levels (P<0.001). SP-D levels were negatively correlated with the neutrophil percentage in BALF (r(s)=-0.5255, P<0.01). SP-D levels in BALF in children with increased blood C-reactive protein levels (>8 mg/L) were significantly lower than in those with a normal level of C-reactive protein (P<0.05). Compared with those in children without wheezing, SP-D levels in children with wheezing were significantly lower (P<0.01). There was no correlation between SP-A levels and clinical characteristics.

CONCLUSIONS

SP-D levels in BALF are significantly higher than SP-A levels, and have a certain correlation with clinical characteristics in children with pneumonia. As a protective factor, SP-D plays a more important role than SP-A in regulating the immune and inflammatory responses.