ATLANTA -- U.S. consumers once again are using credit cards to pay for basics, such as gasoline and groceries, Bloomberg reports. The dollar volume of purchases paid with plastic rose 10.7 percent in June from a year ago, while the transaction numbers jumped 6.8 percent, according to FirstData Corp.??s SpendTrend report.

Silvio Tavares, FirstData senior vice president, attributes the increase to pump prices. "Consumers, particularly in the lower-income end, are being forced to use their credit cards for everyday spending like gas and food," he said. "That??s because there??s been no other positive catalyst, like an increase in wages, to offset higher prices. It??s a cash-flow problem."

With food and gasoline costs rising, Americans have fewer discretionary dollars, which contributes to the slow recovery, according to Tavares. The U.S. Department of Labor found that food prices rose 2 percent January through May, while energy climbed 8.2 percent during the same time.

With food and fuel price swings being "dramatic," the volume of gasoline purchased on credit advanced 39 percent in June from a year earlier, said Tavares. Food shopping jumped 5 percent after dropping 7 percent in 2010.

The average transaction value for credit card purchases were higher than the gain for debit card buys. That shows consumers are turning to credit to for necessities, he said. One bright spot has been falling gasoline prices this summer, which on July 19 had declined 7.6 percent from a nearly three-year high on May 4.