A rally in Jacobs Engineering ( JEC) shows the infrastructure sector can be bought again, Jim Cramer said on CNBC's "Stop Trading!" segment Tuesday. Jacobs, which "blew the cover off the ball" with its recent earnings, single-handedly vanquished frustration caused over the last few weeks by Shaw Group ( SGR) and Halliburton ( HAL), Cramer said. "This signals it's time to buy Fluor ( FLR) and McDermott ( MDR). Jacobs' good fortune highlights that most U.S. infrastructure concerns are "international companies" that are more dependent on spending in Bahrain and China than by Texas utilities. "Infrastructure is global in nature, not U.S. in nature." In another sector, Cramer praised Medtronic ( MDT) on a belief that the federal government won't cut back Medicare and Medicaid reimbursements for its devices as much as feared. Cramer also reiterated his belief that trading in the Oil Services Holders ( OIH) fund is being manipulated. He noted the ETF "snapped back nine points" since being "jammed down" toward $130 last week during an options expiration. "The SEC is busy investigating hedge funds. Why don't you check out what happened in the OIH?"