— Last July, the state Department of Education Professional Standards and Practice Commission opened an investigation into allegations against Michael Zack, a substitute teacher in Northumberland County accused of sending explicit text messages to female students at Shamokin High School.

A month later, the commission suspended Zack’s teaching license. Zack, 24, was sentenced last month to six months house arrest and must register as a Megan’s Law offender.

In January 2012, the professional standards commission opened an investigation into allegations that Kevin DeFrancesco, a teacher in Mercer County’s Jamestown School District had engaged in similar conduct with two girls — ages 13 and 14. In March, the commission suspended DeFrancesco’s license. In November, DeFrancesco, 29, was sentenced to 27 months in prison.

Shane Putorek, 27, from Cambria County a music teacher in the Harmony Area School District was arrested last May on charges alleging he raped a 15-year-old boy. He is awaiting trial. Putorek surrendered his license before the commission needed to take any action, PDE records show.

These were three of 563 misconduct investigations opened against teachers in Pennsylvania last year, more than double the number reported in the prior year.

Gov. Tom Corbett’s budget includes a plan to increase the cost of a license for a would-be teacher by one-third to cover the cost of hiring staff to deal with a dramatic increase in allegations of teacher misconduct.

Tim Eller, a Department of Education spokesman, said that the Department of Education gets about 36,000 new applications for licenses each year — including 21,000 level I certificates for brand-new teachers and 14,000 certificates for level II teachers, who have completed the initial training required for level I teachers.

The Department of Education plans to hire an addition attorney and a law clerk, while the Professional Standards and Practices Commission will also get another attorney and a law clerk, Eller said.

While the allegations of sexual misconduct grab most of the headlines, Eller said there appear to be a number of other factors at play, including the state’s investigation of allegations of wide-spread cheating by teachers during state standardized tests.

A Pennsylvania State Education Association spokesman said the union certainly frowns upon cheating by teachers. But the union also believes that the Corbett Administration has suggested that the problems are more widespread than they actually are.

“Secretary (Ron) Tomalis seemed to suggest that the scrutiny had contributed to a statewide drop in test scores,” Wythe Keever of the PSEA said. “It is one thing to say that you have evidence that there was cheating involving 100 teachers, but it’s another thing to say thousands across school districts were involved in a conspiracy to inflate test scores.”

There are about 120,000 public school teachers in Pennsylvania.

Even with the dramatic increase in allegations, complaints about teacher misconduct are still less common than similar complaints about licensed professionals in other fields. There are more than 900,000 professionals employed in jobs that require licenses governed by boards overseen by the Department of State, said Ron Ruman, a Department of State spokesman.

Last year, there were 3,790 investigations opened against individuals employed in a field overseen by one of the 28 boards — including professions in such wide-ranging fields as doctors, nurses, dentists, architects, cosmetologists, real estate agents, social workers, car sales people and veterinarians.

In 2012, there was 1 investigation for every 237 licensed professionals, compared to 1 complaint per 213 teachers.