Laboratory Studies Of GAS Serologic Markers
Findings: (N=202) Positive throat cultures were obtained from 202 children who were exhibiting symptoms of GABHS infection. ASO titers failed to rise in 46% of patients at 4 weeks and AntiDnaseB failed to rise in 55% of patients. The combination of ASO and/or AntiDnaseB failed to rise in 27% of patients. The authors introduce a measure of the antibody to the C5a peptidase (SCPA) which appears as good or better than the combination of the other antibody titers.
Critique: Timing for AntiDnaseB is somewhat early as other studies indicate it reaches a peak at 8 weeks. It is unclear if this would affect results.
Group A streptococci efficiently invade human respiratory epithelial cells
Findings: Electron microscopy confirmed that streptococci were able to invade epithelial cells and avoided external penicillin and gentamicin. Various strains of streptococci revealed significant differences in their capacity to be internalized (M1 and M12). However, within these strains, M-type M1inv+ was internalized significantly more efficiently than either the M1inv- or M12 strain (potentially explaining outbreaks in north America). M1inv+ was internalized as efficiently as Salmonella typhimurium or L. monocytogenes.