Continued pressure from the hurting oil industry and the strong U.S. dollar helped to drop Ecolab's first-quarter revenue.

Sales for the quarter were $3.3 billion, down 1 percent from the same quarter a year ago and in line with what analysts were expecting. The St. Paul-based company said, using local dollars, sales would have increased ­4 ­percent.

Net income was $233 ­million, up from $191 million last year. Earnings per share increased 24 percent to 77 cents. Excluding one-time events and charges, earnings per share were 80 cents. Analysts predicted 81 cents per share.

"While food service and light industrial markets ­continue to show improving trends, energy markets contracted faster than expected and currency head winds have increased," Chief Executive Douglas Baker Jr. said in a statement. "We have adjusted our earnings outlook for the year and continue to look for strong earnings growth in 2015."

The company revised its forecast for the year downward to earnings per share in the $4.45 to $4.60 range. ­Previous guidance was $4.50 to $4.70.

Ecolab shares fell $3.12, or 2.69 percent, to close Tuesday at $112.97.

Catherine Roberts