Cal. Gov. Code § 25480
In any county which does not employ a purchasing agent the board of supervisors shall annually or at such lesser intervals as it deems appropriate advertise for at least 10 days in a newspaper of general circulation in the county for sealed bids for furnishing the county with stationery, clothing, bedding, groceries, provisions, drugs, medicines, and all other supplies. If there is no newspaper published in the county, notices calling for bids shall be posted in three public places in the county.
This section shall not apply to purchases or contracts for medical or surgical equipment or supplies, or for professional services, for a county hospital so long as an appropriation for the costs of such purchases or contracts is included in the county budget.
As used in this section, "medical or surgical equipment or supplies" means only equipment or supplies commonly, necessarily, and directly used by or under the direction of a physician and surgeon in caring for or treating a patient in a hospital.
Ca. Gov. Code § 25480