instruction: give the number of patients diagnosed with streptococcal septicemia and had lab test for blood gas .
response: SELECT COUNT(DISTINCT demographic.subject_id) FROM demographic INNER JOIN diagnoses ON demographic.hadm_id = diagnoses.hadm_id INNER JOIN lab ON demographic.hadm_id = lab.hadm_id WHERE diagnoses.long_title = "Streptococcal septicemia" AND lab."CATEGORY" = "Blood Gas"