ABSTRACT
Objective:
To investigate the
prevalence and clinical characteristics of
Mycoplasma pneumoniae( Mp)
genotypes and subtypes in
children in Tianjin.
Methods:
Children with
pneumonia admitted to Tianjin
Children′s
Hospital from December 2017 to December 2019 were selected as the
research objects.
Bronchoalveolar lavage fluid was collected by fiberoptic
bronchoscopy. The positive samples were detected by real-
time fluorescent quantitative
PCR and Mp
culture.
PCR-
restriction fragment length polymorphism(
RFLP) and multiple
variable number tandem repeats were used for genotyping. Detailed clinical and
laboratory data were collected for all cases.
Results:
The results of
RFLP showed that there were 138 cases (78.9%) of typeⅠand 37 cases (21.1%) of type Ⅱ; 37 cases of type M3-5-6-2, including six subtypes B, G, M, S, V and Y; 138 cases of M4-5-7-2 were detected, including seven subtypes of E, J, P, U, X, Z and a. In M3-5-6-2 type, there were 1 case of P1-Ⅰtype (2.7%), 36 cases of P1-Ⅱtype (97.3%), 137 cases of P1-Ⅰ type (99.2%) and 1 case of P1-Ⅱ type (0.7%) in M4-5-7-2 type. There was no significant difference in
genotype distribution among different
age groups. There were statistical differences in the distribution of four
seasons among the 13
genotypes of B, G, M, S, V, Y and E, J, P, U, X, Z, a. All Mp infected
children had symptoms of
fever and
cough. The
hospitalization time,
fever duration, high
fever (>39℃),
cough duration,
skin changes,
digestive system symptoms and
liver function
injury rate of P1-Ⅰ/M4-5-7-2
pneumonia children were higher than those of P1-Ⅱ/M3-5-6-2
pneumonia children, but the difference was not statistically significant. The WBC count of P1-Ⅱ/M3-5-6-2 types was higher than that of typeⅠand M4-5-7-2; the LDH of P1-Ⅰ/M4-5-7-2 was higher than that of Ⅱ and M3-5-6-2, with statistical difference. There was no significant difference in the
incidence of inflammatory consolidation,
atelectasis, pleural thickening and
pleural effusion among different
genotypes.
Conclusions:
Mp
infection in
children with
pneumonia in Tianjin is mainly P1-Ⅰ/ M4-5-7-2, and P1-Ⅱ is on the rise. P1-Ⅰ and M4-5-7-2 were associated with
fever and severe symptoms.