US inflation probably worsened last month on the back of higher prices for gas, eggs, and used cars, a trend that could make it less likely that the Federal Reserve will cut its key interest rate much this year. On Wednesday the Labour Department is expected to report that in December the consumer price index rose 2.8% from a year ago, according to economists surveyed by FactSet, up from a 2.7% yearly increase in November. It would be the third straight rise, after inflation fell to a 3 1/2 year low of 2.4% in September. The uptick could fuel ongoing concerns among many economists and in financial markets that inflation has gotten stuck above the Fed's 2% target. Such concerns have sent interest rates on Treasury securities higher, which has also pushed up borrowing costs for mortgages, cars, and credit cards, even as the Fed has cut its key rate. Last Friday's unexpectedly strong jobs report caused stock and bond prices to plunge on fears that a healthy economy could keep inflation