PriceSmart Inc.'s fiscal fourth-quarter profit fell from the same period last year, as higher revenues were not enough to outweigh higher costs of business, the company announced Wednesda.

The San Diego, Calif.-based operator of membership warehouse clubs saw its net income decline on a year to year basis to $12.7 million, or $0.42 per share, from $13.2 million last year, or $0.44 per share, for the quarter ended Aug. 31.

This missed the consensus estimates of experts polled by Thomson Reuters, who expected $0.54 per-share earnings for the quarter.

Breaking down the report, sales grew - but costs grew even more.

PriceSmart's total revenue rose 22 percent to $447 million, in line with a 22-percent increase in its net warehouse club sales, which grew to $436 million compared with $357 million a year ago.

But costs also rose sharply. The cost of goods sold at net warehouse clubs grew to more than $371 million from $301 million. Adding operating and general and administrative expenses, total operating expenses ballooned to $428.7 million from $345.6 million a year ago.

One reason for optimism is the continued growth in net warehouse club sales. The company announced on Wednesday that in October 2011 - in the first quarter of its new fiscal year - net warehouse club sales rose 23.9 percent to $159.6 million from $128.8 million in October 2010. For the two-month span ending Oct. 31, net warehouse club sales increased 24.7 percent.

PriceSmart is the largest membership warehouse club chain in Central America and the Caribbean.

As of 2:30 p.m. ET, shares of PriceSmart plunged 13.47 percent to $67.18. On Tuesday, the company had closed at $77.71.