| Background: Staphylococcal scalded skin syndrome (SSSS) is the term used for a collection of blistering skin diseases induced by the exfoliative toxins (ETs) of Staphylococcus aureus. It primarily affects neonates and young children. The morbidity of SSSS is rising gradually recently. However, even with appropriate antibiotic therapy, the mortality is still 3% in children, and over 50% in adults, reaching almost 100% in those with underlying disease. ET is regarded as an exotoxin. There are four serological forms of staphylococcal ETs (ETA, ETB, ETD and ETC), of which ETA and ETB can cause SSSS in human.The epidemiological study releaves that different ET serotypes shows a significant geographical distribution. In America, Europe and Africa, ETA is the predominant ET; in contrast ETB has been reported to be more common in Japan. The ETD gene-positive strain might be related to the development of deepseated infections such as furuncles, cutaneous abscesses and finger pulp infection. In past years, It was reported by European and Japanese researchers that SSSS was becoming increasingly associated with Methicillin-resistant Staphylococcus aureus (MRSA). Unfortunately, there were few reports about ET serotype and MRSA prevalence associated with SSSS in China.Objective:To explore the distribution of three exfoliative toxin (ET) serotypes among staphylococcus aureus (SA) isolated from children with staphylococcal scalded skin syndrome (SSSS), comparing with impetigo vulgaris and cutaneous abscess. To investigate the resistance of SA to common antibiotics and the ratio of MRSA, which is benefit for clinical antibiotics option.Methods:108 strains of SA from SSSS, impetigo vulgaris and cutaneous abscess were identified for their exfoliative toxin A,B and D genes by the multiplex PCR. Kirby-Bauer scrip was used for testing the susceptibilities of SA to twenty antibiotics.Results:1. Among 36 SA isolated from SSSS, 100%(36/36) strains were ET producers, including 2 ETA(6%), 7 ETB(19%), 27 both ETA and ETB(75%). Of the 36 isolates from impetigo vulgaris,78% (28/36) strains were positive in terms of ET production with 5 ETA(14%) and 23 both ETA and ETB(64%) . No serotype B producing strains were found. On the other hand, only one strain SA (3%) from cutaneous abscess were ET positive which produces both ETA and ETB. All of the 108 SA, no ETD strains were detected. There is a statistically difference in the distribution of ET serotype among three diseases(x2= 89.4,P<0.01). And the proportion of ET-producing strains of three groups also has a statistically difference (x2= 80.0,P<0.01).The proportion of ET-producing strains in SSSS group is much higher than that in impetigo vulgaris(x2=9,P<0.01) and cutaneous abscess(x2=68.1,P<0.01). Moreover, the proportion of ET-producing strains in impetigo vulgaris group is much higher than that in cutaneous abscess(x2=42.1,P<0.01).2. The ratio of Staphylococcus aureus resistant to penicillin among each subgroups were 100%, 97%, 92% respectively;The ratios were 100%, 97%, 97% to ampicillin respectively; 89%, 89%, 78% to erythromycin respectively; 89%, 92%, 75% to clarithromycin respectively; and 78%, 75%, 36% to clindamycin respectively. While three groups of SA were sensitive to other 15 common antibiotics such as cephalosporin. Two strains MRSA were found in abscess group.Conclusion:1. In Chongqing, ET-producing SA is the most common pathogenic bacteria among SSSS and impetigo vulgaris, in which most strains are both ETA and ETB producers. There is a certain correlation between the clinical manifestation of SA infection and the serotype of exfoliative toxins.2. Staphylococcus aureus from three groups were highly resistant to penicilin, ampicillin, macrolides and clindamycin,while they were sensitive to other 15 common antibiotics such as cephalosporin.3. Few MRSA strains were found in SSSS and impetigo vulgaris patients in this area.
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