| Part ⅠObjective:To understand the epidemic trend of scarlet fever and demographic features of children with culture-proven scarlet fever in Shanghai from 2002 to 2013.Methods:We collected all notifiable cases with culture-proven scarlet fever from the Children’s Hospital of Fudan University (CHFU) between Jan 2002 and Dec 2013 and analyzed the demographic data of children of scarlet fever.Results:The number of children clinically diagnosed as scarlet fever ranged from 151 (in 2003) to 4076 (in 2011) per year, and the number of confirmed scarlet fever cases ranged from 39 (2012) to 1805 (in 2011). The proportion of positive throat swab culture for GAS among patients between 2002 and 2013 were 21.8% (39/179),27.8%(42/151).33.9%(129/380),35.2%(252/715),47.1%(256/543), 43.6%(430/987),42.7%(315/738),41.5%(196/472),54.2%(187/345),44.3% (1805/4076),46.3%(1136/2455),47.0%(959/2038) respectively. Three epidemic waves were observed in 2005,2007 and 2011 during the past twelve years and the peak was striking in 2011 with 3- to 20-fold increase in case number, compared to the numbers in previous years. The activity of scarlet fever remained the relative high level in 2012 and 2013. Scarlet fever is prevalent throughout the year but peaks between April and June during late spring to mid-summer in Shanghai, and a smaller peak can also be observed between November and January in the winter season. The seasonal pattern of scarlet fever is similar by year. Of 5746 children with culture-proven scarlet fever, boys outnumbered girls (59.5%～71.8%versus 28.2%～40.5%). Overall, children aged 4-9 years accounted for 86.8%(4990/5746) and children attending kindergarten and school, accounted for 96.6%(5548/5746). All cases fully recovered and no complications and fatal outcome were observed after 7-10 day’s antibiotic therapy.Conclusion:An unprecedented outbreak of scarlet fever occurred in Shanghai in 2011. Scarlet fever usually peaks in April-June and November-January in Shanghai. Boy are more affected than girls and the major susceptible children aged between 4 years and 9 years.Part ⅡObjective:To actively monitor the molecular characterization of endemic GAS st rains isolated from children with scarlet fever and asymptomatic GAS carriers in 2011 during a major outbreak and in 2012-2013 after the outbreak, and observe the dynamic distribution of emm types and super antigen profiles of GAS strains by year.Methods:We collected the throat swab specimens from children with scarlet fever at our hospital between April-June and November-December in 2011-2013. At the same time, we collected the throat swab specimens in May and December from healthy children in the community and the primary schools where there were scarlet fever cases were reported. GAS was isolated from the swab samples submitted to the CDC reference laboratory. GAS isolates were characterized by emm typing, superantigen profiles, PFGE genotypes and MLST.Results:A total of 384 (50.5%) GAS isolates were recovered from 760 scarlet fever patients,13 (43.3%) GAS isolates were recovered from 30 asymptomatic close contacts in June 2011 at an elementary school where the most clusters of scarlet fever cases were reported,23 (10.7%) GAS isolates were recovered from 215 asymptomatic children in the community in 2012-2013, and 23 (10.7%) GAS isolates were recovered from 215 asymptomatic children in the community in 2012-2013,32 (6.5%) GAS isolates were recovered from 492 asymptomatic children from the primary schools in May in 2011-2013, and 8 (2.2%) GAS isolates were recovered from 360 asymptomatic children from the primary schools in December in 2011-2013. Six emm types were detected in 428 GAS isolates, including emml, emm12, emm3, emm22, emm75, and emm89. Among 371 GAS isolates recovered from scarlet fever patients, emm12 (77.6%) was the most common type, followed by emm1 (20.5%), emm 75 (0.8%), emm22(0.5%), emm3(0.3%), and emm89 (0.3%). Among 57 GAS isolates recovered from asymptomatic carriers, emm12(86.0%) was the most common type, followed by emm1(10.5%), emm 75 (3.5%)。Altogether, emm12 was the predominant type over 3 years. However, the proportion of emml showed an increasing trend in 2013, accounting for 36.1% and 20.0% of emm types in patients and carriers, respectively. Nine superantigens were detected in 279 GAS isolates recovered from scarlet fever patients, including speA (19.0%), speC (87.1%),speG (95.7%),speH (54.5%),spel (73.9%),speJ (18.6%),speL (0.4%), ssa(90.0%)and smeZ(77.0%). Based on the PFGE patterns and similarity, the majority of emm 12 type GAS isolates were clonally related. The allelic profiles of seven housekeeping gene loci generated by MLST revealed that all emm12 type and subtypes with different PFGE patterns belonged to ST36, emml belonged to ST28, emm- 3 belonged to ST315, emm-22 belonged to ST46, emm 75 belonged to ST49, emm89 belonged to ST101.Conclusion:emm12 GAS strain caused the 2011 large outbreak of scarlet fever in Shanghai and also remained the dominant strain in 2012 and 2013. The most emm12 GAS strains were clonally related. Besides, emml GAS strain was also the common endemic strain and the proportion of emml GAS strain increased markedly in 2013. The carriage of GAS in asymptomatic children in the community and the school during the peak months were of particular note, furthermore, the distribution of emm types was similar among patients and carriers, which has some implication in the spread of GAS in the susceptible children.Part ⅢObjective:To monitor the antimicrobial resistance patterns of GAS isolates and guide the rational antibiotic treatment for the GAS infectionsMethods:Antimicrobial susceptibility testing was performed on 371 GAS isolates from patients and 57 GAS isolates from carriers through the disk diffusion method.Results:All tested GAS isolates were all susceptible to benzylpenicillin, ampicillin, cefepime, ceftriaxone/cefotaxime, vancomycin, linezolid and levofloxacin. Resistance to erythromycin, azithromycin, clindamycin and tetracycline among 371 GAS isolates recovered from patients was detected in 98.9%.98.7%,98.7% and 74.4% of isolates, respectively. Resistance to erythromycin, azithromycin, clindamycin and tetracycline among 57 GAS isolates recovered from carriers was detected in 94.9%,94.7%,96.5% and 91.2% of isolates, respectively. Besides, a few of GAS isolates were resistant to chloramphenicol.Conclusion:GAS strains circulating in Shanghai were susceptible to β-lactamase antibiotics.GAS resistance to macrolides and clindamycin was serious in Shanghai. |
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