Flies buzzed around the fluorescent lights of the operating rooms at Sterling Regional Medical Center, prompting the ire of the medical director.

Yet, weeks later, the insect infestation remained a problem, inspectors noted when they visited in November 2015. Staffers had resorted to vacuuming or swatting the bugs, records show.

At Memorial Hospital in Colorado Springs, technicians failed to follow manufacturer instructions for pre-cleaning vaginal probes, putting patients at risk of infection, inspectors found in May 2016.

And this year, Porter Adventist Hospital in Denver is under fire for failing to promptly notify patients of questionable sanitary practices after the disclosure that a doctor there last April found a bone fragment from a previous surgery stuck to a tool he was about to use.

The issue of whether hospitals are doing enough to prevent infections from spreading is of vital importance from the metro Denver area to the Eastern Plains and Western Slope.

“Hospital-acquired infections are an incredible concern for patient safety and for the community,” said Hollynd Hoskins, a lawyer who sued Swedish Medical Center in Englewood for lapses that allowed an HIV-infected surgical tech to steal a painkiller syringe from an operating room. “This is a known risk. It’s absolutely critical that all the hospitals, as well as the state and federal agencies that have responsibility for oversight monitoring and enforcement, are sure there is surveillance control and protection.”

Statistics raise concerns on how Colorado is faring in preventing such infections.

The Centennial state ranked eighth-highest in the nation for the percentage of reviewed hospitals that face potential fines for hospital-acquired conditions, according to numbers from the Centers for Medicare & Medicaid Services, or CMS. The conditions surveyed included infections in patients with catheters in major veins and their bladders as well as eight other patient problems.

Fifteen of 48 Colorado hospitals faced potential fines based on the CMS data, according to data collected from January 2015 through December 2016. The review did not include certain rural hospitals. Notably, Colorado ranked No. 9 on the same list in 2014, based on data from January 2012 through December 2013.

How seriously a hospital takes the issue can be a matter of life and death for patients. About 1.7 million healthcare-associated infections occur annually in the nation, according to the Centers for Disease Control and Prevention. About 99,000 of those patients die each year, the CDC reports, causing an estimated $20 billion in estimated health care costs.

“Each year, about 1 in 25 U.S. hospital patients is diagnosed with at least one infection related to hospital care alone,” the CDC says.

“Hospitals are making a valiant effort, but they are fighting a battle against a very determined and resourceful enemy,” said Phil Danielson, a University of Denver professor who specializes in infectious diseases.

More drug-resistant strains of bacteria have developed in the past 10 years than in all the previous years of antibiotic use, he said. And intensive care units are jammed with people with compromised immune systems who often rely on catheters or IV lines, all of which create an environment for infections to proliferate.

“In some hospitals, they are seeing patients in ICU with infection rates as high as 50 percent,” Danielson said.

Research is underway on self-cleaning metals for surgical instruments as one way to reduce such infections, he said. Silver-plated hospital equipment may not be on the horizon, but “there are some metals that seem to have properties about them that seem to inhibit bacterial growth,” Danielson said.

A team of 15 state officials monitors how hospitals and other health facilities in Colorado are doing on preventing facility-acquired infections. In addition, Colorado is one of 10 state health departments in the country participating in the CDC’s Emerging Infections Program, which allows for extra monitoring and research of hospital-acquired infections.

In Colorado, one issue in particular has raised concerns among public health officials. The state has been an outlier when compared to others on infections of Clostridium difficile, a diarrhea disease that generally occurs in patients exposed to health care and antibiotics. About 14,000 deaths in the nation annually are tied to this specific infection, according to the CDC.

Colorado’s acute-care hospitals have historically performed worse than their peers in other states on the rate of patients infected by Clostridium difficile, according to data from August 2014 through July 2016. Colorado hospitals reported 2,668 of their patients ended up with that infection during that time frame, resulting in more than 3.2 million hospital patient days. Deaths were not included in the tallies.

Hospitals that performed poorly on the rate of patients with Clostridium difficile complications from August 2014 to July 2015 were Penrose Hospital in Colorado Springs, St. Anthony Hospital in Denver, St. Anthony Hospital in Westminster, Medical Center of Aurora, St. Luke’s Hospital in Denver, Good Samaritan Hospital in Lafayette, Parker Adventist Hospital and Swedish Medical Center in Englewood, the state reported. From August 2015 to July 2016, Penrose, St. Anthony in Denver, Parker Adventist and St. Luke’s again had a worse rate than the national average. Joining them were St. Mary-Corwin Medical Center in Pueblo, Medical Center of the Rockies in Loveland and Lutheran Medical Center in Wheat Ridge, the state said.

A new annual report on health care-associated infections is due in July. Preliminary data show that Clostridium difficile complications tied to hospitals are leveling off, said Wendy Bamberg, Colorado’s health care-associated infections program manager.

Of about 50 Colorado hospitals reporting to the CDC in April 2016 through March 2017, the most recent time period for available data, the state scored better than the national infection rate in two other high-risk areas, central-line associated bloodstream infections and catheter-associated urinary tract infections.

CMS inspection reports from last year show that inspectors cited seven of 21 hospitals for lapses in infections protocols.

While hospitals still were researching issues identified in The Denver Post’s reporting and research, their officials stressed that they strive to correct problems when they surface.

Officials at Sterling Medical Center said that when the issue with the flies surfaced, they acted to address the problem and find out the cause. Hospital leaders cleared the operating room and sterilized all equipment before surgeries resumed, they said. The hospital also corrected structural issues, improved equipment inspections and educated staff on the importance of immediately reporting and correcting problems, they added.

“When this issue was recognized, it was addressed expeditiously and effectively with ongoing education and inspections put into place to prevent future issues,” said Hoyt Skabelund, chief executive officer at Sterling. “Patients in Sterling and northeast Colorado can be confident in the documented safety and quality of care that we provide.”

Officials with Centura Health, which owns three hospitals that two years in a row had a high rate of Clostridium difficile infections, said they take the condition seriously and diligently monitor such infections. Centura put together a task force to study the high rate of infections, and also is working to reduce the use of antibiotics at St. Anthony in Denver and St. Anthony in Westminster. Those hospitals also initiated additional focused cleaning with bleach and hydrogen to further drive down those infections, according to officials.

Centura’s Porter Adventist hospital resumed surgeries April 12 after officials there warned, through letters, 5,800 patients of a separate infection risk related to its sterilization procedures, and after they addressed additional concerns related to water quality. The Colorado Health Department has announced that a number of patients at Porter suffered surgery-related infections between July 21, 2016, and April 5, although state officials say they don’t know whether the infections are related to the problems in how the hospital cleaned surgical instruments.

“We are cooperating with the state officials and have resumed surgeries now,” said Centura Health spokeswoman Wendy Forbes.

But lawyer Hoskins said the fact that patients weren’t warned until about a year after the bone fragment was found at Porter raises concerns.

“The ball has been dropped on numerous levels,” said Hoskins, who is representing patients who plan to sue the hospital. “It’s really something we should all be concerned about. There needs to be open transparency to the public about what exactly went wrong and when Porter officials knew about this.”

Editor’s note: This story was updated at about 4:30 p.m. Monday with a comment from Sterling Medical Center.