Which of the following is a common feature of both Staphylococcus and Streptococcus species?

Staphylococcus and Streptococcus species share the common feature of producing exotoxins, which are toxic substances secreted by bacteria into their surrounding environment. These exotoxins can contribute to the pathogenicity of both genera. For example, some Staphylococcus species produce toxins such as toxic shock syndrome toxin (TSST), while certain Streptococcus species, like Streptococcus pyogenes, produce pyrogenic exotoxins.

The other options do not hold true for both genera. Staphylococcus species are typically gram-positive, whereas Streptococcus species are also gram-positive, so the option regarding gram-negative organisms is not applicable. In terms of catalase activity, Staphylococcus species produce the enzyme catalase, which breaks down hydrogen peroxide, while Streptococcus species do not produce this enzyme, making this aspect a distinguishing feature rather than a commonality. Lastly, both genera are primarily facultatively anaerobic, with Staphylococcus being able to grow in aerobic conditions, whereas Streptococcus generally prefers anaerobic environments. Therefore, only the ability to produce exotoxins serves as a shared characteristic between the two.