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Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) is rapidly spreading worldwide. MRSA USA300 is a clone of increasing public health concern among rapidly disseminating CA MRSA strains in the United States (1). [...]

The NADase (Nga) of group A streptococci (GAS) has been implicated in the pathogenesis of diseases such as streptococcal toxic shock-like syndrome (STSS) and necrotizing fasciitis. In this study we found that the proportion of NADase-positive strains among clinical isolates in Japan has increased over time. The GAS strains studied could be divided into three groups: strains lacking NADase activity, strains with low NADase activity, and strains with high NADase activity. The older strains, isolated before 1989, belonged to the 'no activity' group. Analysis using GST-Nga recombinants revealed that nga alleles of representative older strains encode inactive Nga. Mutational analysis of the GST-Nga recombinants suggested that residue 330 could be associated with reduced activity, based upon deduced amino acid sequences. We also investigated NADase activity of streptococcal strains other than GAS. All group G streptococcal isolates from STSS patients possessed nga genes encoding active enzymes.

The survival of 58 diarrheagenic strains and of 15 nonpathogenic Escherichia coli strains are determined after drying at 35 degree Celsius for 24 h in paper disks to determine desiccation tolerances of bacterial strains. The effects of pH, food ingredients such as sucrose, storage period, and storage temperature are examined and the survival of these desiccated bacteria in selected dry foods after artificial inoculation are studied.