The federal government filed a sex and race discrimination suit yesterday in U.S. District Court here against 55 area printing shops, three major printers unions and five of those unions' local chapters.

Some of the defendants accused by the Equal Employment Opportunity Commission of discriminating against women and blacks include Merkle Press Inc., McArdle Printing Co., Local 101 of the International Typographical Union, Local 285 of the Graphic Arts International Union and Local 72 of the International Printing and Graphic Communications Union.

According to the complaint, blacks and women often were required to undergo educational and job tests that had nothing to do with the jobs they were seeking.The complaint alleges that the defendants used a "word-of-mouth" communication network to keep blacks and women from getting jobs or promotions. The EEOC also accuses the unions and job shops of discriminating by putting only white males in charge of hiring and promotions.

The EEOC class-action suit was filed after the defendants and Local 449 of the Washington Printing Specialties and Paper Products Union, which represents many blacks, and Local 42-B of the Graphic Arts International Union, which represents several women, failed to reach a "conciliatory agreement" ordered by the EEOC in 1976.