Mycoplasma pneumoniae Macrolide Resistance and MLVA Typing in Children in Beijing, China, in 2016: Is It Relevant?

OBJECTIVE: The aim of this study is to investigate the macrolide resistance rate and molecular type with multiple-locus variable-number tandem-repeat analysis (MLVA) of Mycoplasma pneumoniae of Beijing in 2016 in pediatric patients. METHODS: Real-time quantitative polymerase chain reaction (PCR) was used to identify M. pneumoniae, and MLVA was performed. The domain V of the 23S rRNA was sequenced to detect macrolide-resistant point mutations. We also investigated the activities of antibiotics against M. pneumoniae isolates in vitro. RESULTS: The PCR detection rate of M. pneumoniae in children in Beijing was 40%, and the macrolide resistance rate was 66%. The A2063G mutation in the 23S rRNA V region is the dominant mutation (137/146, 93.84%), whereas the A2064G mutation is rare (9/146, 6.16%). Seventy-three samples were typed successfully by MLVA typing, including 86.3% (63/73) were MLVA type 4-5-7-2, and 13.7% (10/73) were MLVA type 3-5-6-2. No other types were found. No strains were resistant to levofloxacin or tetracycline. CONCLUSION: In 2016, a specific decrease in the macrolide resistance rate occurred in Beijing. The detection rate and macrolide resistance rate of outpatients are lower than those of inpatients. The A2063G mutants M. pneumoniae have high levels of resistance to erythromycin and azithromycin. The primary MLVA type is 4-5-7-2, followed by 3-5-6-2. No other MLVA types were detected. No strains resistant to tetracycline or levofloxacin were found in vitro.

P1 gene of Mycoplasma pneumoniae in clinical isolates collected in Beijing in 2010 and relationship between genotyping and macrolide resistance.

BACKGROUND: Mycoplasma pneumoniae is a common pathogen that caused community-acquired pneumonia (CAP). P1 protein served as major adhesion and immunodominant protein in Mycoplasma pneumoniae, but little about P1 gene was learned and the relationship between P1 genotype and macrolide resistance has yet to be explored. METHODS: The DNA sequence of the entire P1 gene from 35 strains isolated from clinical specimens collected in Beijing, China, in 2010 was determined. The resulting sequences were checked for known macrolide resistance mutations, such as A2063G, A2064G, C2617G in domain V of 23S rRNA. Antibiotic susceptibility test was done to further identify macrolide resistant strains. RESULTS: Thirty-four clinical strains were type 1, and were identical to type 1 reference strain MP129. Only one clinical strain, MpYYM22, was type 2, and proved to be variant 2c. One synonymous point mutation in the P1 type 1 gene from two isolates was identified relative to the MP129 P1 sequence at nucleotide position (nt) 552 (C>A), while another two isolates had missense mutations at nt 2504 (G>A). This point mutation caused an amino acid change from glycine to glutamic acid. An AGT tri-nucleotide variable-number tandem repeat (VNTR), coding for serine and repeating 6-11 times, up to 15-16 times, was found in the region between the RepMP4 and RepMP2/3 elements in the 35 isolates examined. All 35 clinical strains, including MpYYM22, demonstrated macrolide resistance with the range of minimum inhibitory concentration (MIC) of erythromycin from 64 to 256 µg/ml, having an A2063G transition in domain V of the 23S rRNA gene. CONCLUSIONS: P1 type 1 was the dominant type of Mycoplasma pneumoniae in Beijing in 2010, although variant 2c strains were present. More samples are needed to determine whether there is a relationship between the P1 genotype and macrolide resistance, as the 35 strains examined did not allow a conclusive result. However, the AGT tri-nucleotide VNTR may be a more informative locus for multi-locus VNTR analysis.

[Treatment of Cr( VI) in deoxygenated simulated groundwater using nanoscale zero-valent iron].

Laboratory experiments and theoretical modeling studies were performed to investigate the mechanisms of Cr( VI) removal from deoxygenated simulated groundwater using nanoscale zero-valent iron, and to evaluate influencing factors and kinetics based on zeta potential, redox potential, ferrous concentrations, and the pe-pH diagram of Fe-Cr-H2O system. Experimental results demonstrate that the removal efficiency of Cr(VI) decreases with the increasing Cr( VI)/Fe mass ratio. When the Cr(VI)/Fe mass ratios are 0.025, 0.050, 0.075, and 0.100, the corresponding Cr(VI) removal rates are 100.0%, 85.6%, 72.7% and 39.6%, respectively. The Cr( VI) removal is favorable at acidic pH with fixed Cr(VI)/Fe mass ratio of 0.100. When pH are 3.0, 5.0, 7.0, 9.0 and 11.0, the Cr(VI) removal rates are 73.4%, 57.6%, 39.6%, 44.1%, and 41.2%, accordingly. The Cr(VI) removal follows the pseudo second-order kinetics. When pH is 7.0 and Cr(VI)/nZVI mass ratio is 0.025, the rate of Cr(VI) removal is the highest with rate constant at 9.76 x 10(-3) g x (mg x min)(-1). The conversion from Cr2O7(2-) to Cr3+ should be instantaneous when Cr2O7(2-) is absorbed on the surface of Fe. The Cr(VI) was reduced to Cr(III), which was subsequently incorporated into the FeOOH shell and formed a Cr-Fe film. The film once formed could further inhibit the electron transfer between Cr2O7(2-) and Fe. Then Cr(V) removal was primary controlled by the adsorption process.

[The analysis of the test results in HIV screening laboratory of Beijing Friendship Hospital in 2008].

OBJECTIVE: According to test results of the Hospital of AIDS screening laboratory in 2008, after counting analysis to assess the prevalence of AIDS, we can early detect positive cases in the future and effectively control the spread of AIDS. METHODS: All serum samples were screened by ELISA method and we reexaminated the samples by PA. As long as one result is positive by the two methods, then we sent the positive samples to Beijing Center for Disease Control and Prevention by Western Blot method to confirm the result. RESULTS: A total of 21 467 samples were detected and 29 (13.5% 0) were positive screening results. We confirm there were 7 (24.1%) positive samples and 12 (41.4%) suspected samples. We researched the epidemiology of the specimens by its source and age and sex. CONCLUSION: Application of ELISA method for HIV screening test has a practical significance, it is accurate and fit to record the results of the screening test for AIDS.

[Study on genotyping of Mycobacterium leprae and families with multi-cases].

OBJECTIVE: Multiple locus variable number-tandem repeat (VNTR) analysis (MLVA) had been proposed as a means of strain typing for tracking of source and studying the transmission chain of pathogens. However, empirical data for a defined population from scale and duration were lacking for studying the transmission chain of leprosy. METHODS: MLVA on 7 VNTR loci was applied to the strain typing on prevalent Mycobacterium leprae isolates collected from Qiubei county, Yunnan province during 2002-2006 in the study on the relationship between geographic distribution and genotypes of M. leprae. The strain typing, combined with conventional epidemiological investigation was performed to trace the transmission chain. RESULTS: (1) Phylogenetic analyses through application of PAUP 4.0, The M. leprae were grouped into A, B, C, D and E strains according to the allelic range 9, 11-13, 15-26 and > 26 on the GTA9 locus. The strains with 9 copies on GTA9 locus, was named A. (2) Genotypes of strains from the five multi-case families located at North and North-West parts were similar and belonged to A strains. VNTR patterns of intra-family were identical or similar but not identical inter-family. (3) Not only A cluster appeared higher proportion in total isolates but also distributes cluster, indicating ongoing transmission from recent findings. CONCLUSION: VNTR strain typing was suitable to trace the short chain of transmission in both small area and intra-families. Multi-case families might constitute epidemic foci and source of M. leprae in villages, causing the predominant strain or cluster which tends to be those identified in multi-case families and resulted in the spreading of leprosy. A long-term study was underway to reveal whether A strain was predominant strain and to observe the evolution of M. leprae in this spatially and temporally defined endemic population.

[Preliminary study on the genotyping of Mycobacterium leprae on 50 isolates from China].

OBJECTIVE: To understand the genotypic mapping of Mycobacterium leprae identified in China and to compare with those from other countries to select suitable alleles for epidemiological investigation in the transmission chain of leprosy. METHODS: Various number of tandem repeat(VNTR) in genomic DNA of Mycobacterium leprae was used in the present genotyping study. 33 skin biopsies from Wenshan prefecture,Yunnan province and 17 from other parts of China were studied. DNA extracted from skin biopsies of leprosy patients was subjected to PCR followed by agarose gel analysis and DNA sequencing to determine the number of repeats. RESULTS: Loci GGT-5,12-5,21-3 and 23-3 were as highly homogenous as 100%; The homogeneity of loci AC-8, 18-8, 27-5 and rpoT were 97%, 94%, 97% and 85% respectively. Loci GTA-9, AC-9 and 6-7 showed significant allelic diversity in isolates and the diversity of GTA-9 in Mycobacterium leprae isolated from China was also different from those identified other countries. We had subjected loci GTA-9 and the ten loci to phylogenetic tree analysis respectively. CONCLUSION: The present study revealed that the genotype of Mycobacterium leprae identified from China was close to the strains from the Philippines and India although a few loci were somehow differentiate. Locus 12-5 manifested as only 3 copies in China whereas 4-5 copies predominating in other countries. 12-5 locus might serve as a useful marker to diffrentiate Chinese strains from those in other countries. However, further study on the diversity of GTA-9 was needed in China. The molecular typing of Mycobacterium leprae from different geographic areas might be useful in studying the transmission of leprosy.