The city Health Department received notification of 676 cases of methicillin-resistant Staphylococcus aureus since Feb. 27 when hospitals and private laboratories became required to report them, the New York Post reported Sunday. That number is thought to be low because only 21 of 49 labs have reported in so far, the Post said.

"We would assume we would have about 4,000" reports, Melissa Marx of the department's antibiotic-resistance unit told doctors at Columbia University Medical Center last week.

Health officials intend to use the reports to determine whether MRSA is on the rise and whether certain groups of people are at greater risk than others, Marx said.

MRSA is a type of staph infection common in hospital patients and is not treatable with antibiotics. A different strain has been infecting people outside of hospitals.