The employee appeals from the compensation judge’s denial of her claim that she sustained an occupational disease arising out of her employment.

Coleen A. Anderson, the employee, attained a license as a licensed practice nurse (LPN) in 1985.  She worked as an LPN in the Apple Valley Medical Center emergency room until 1992.  The employee left that position because of a work-related injury to her back resulting in restrictions that precluded her from doing hands-on patient care.  In 1993, the employee went to work for Cascade Medical where she worked on a triage nurses’ line, providing medical advice over the telephone to individuals who had questions or problems with their blood glucose monitoring devices.  In 1999, the employee went to work for France Avenue Family Physicians where she worked as a triage nurse responding to patient problems on the telephone until 2002.

In October 2002, the employee went to work for Accurate Home Care, providing pediatric home care for sick children.  The employee worked in the homes of the children, typically in their bedrooms.  Over the two years the employee worked for Accurate, she cared for eight patients.  Of those eight patients, two [Patient A and Patient B] were young children who were positive for Methicillin-resistant Staphylococcus aureus (MRSA).  The employee provided home care to Patient A from October 2002 through February 2003, spending approximately 154 hours with Patient A.  Patient A was a one-year old premature infant with asthma.  The employee’s primary responsibilities for Patient A included feeding, respiratory assistance, tracheotomy care, clearing the child’s breathing equipment of secretions, cleaning respiratory and other medical equipment, weaning the child off a ventilator, monitoring the child’s vital signs, assisting with a nebulizer, performing range of motion exercises, bathing, cleaning and providing the necessary hygiene for the patient.  The employee cared for Patient B from April 7 through July 19, 2003, spending approximately 200 hours caring for the child.  Patient B had a multitude of neuromuscular problems.  The child was on a ventilator and was fed by a G-T tube inserted into the child’s intestine.  The employee’s duties with Patient B were similar to those with Patient A.

The employee left her position at Accurate on October 21, 2004, and was unemployed until she went to work for Edelweiss Home Care, Inc., on February 3, 2005.  At Edelweiss, the employee worked with a 1-year-old child, Patient 1, who was MRSA colonized.  The employer’s records reflect the employee spent 74.5 hours with Patient 1 between February 3 and February 14, 2005.  Patient 1 was on a respirator, a ventilator and had an inserted G-tube and a J-tube which were for feeding.  The employee was responsible for Patient 1's respiratory care, feeding, administering a nebulizer, cleaning the patient’s tubes and equipment, and bathing and dressing the patient.

When caring for Patients A, B, and 1, the employee practiced universal precautions.  These precautions involved wearing latex gloves, hand washing and using extreme care when touching any bodily fluid.  The employee did not wear a mask but she was required to wear a gown, mask or eye protection if there was an expectation or possibility she would come into contact with spurting fluids.

The employee suffers from a number of different medical conditions, including diabetes, and has been insulin dependent since 1975.  She was treated for epigastric pain at United Hospital in 1993, and was later diagnosed with pericarditis.  Her medical history includes insulin-dependent diabetes under “relatively poor control,” depression, chronic sleep disorder, and dyspepsia.  The employee was seen for sternal chest pain in February 1994 and in March 1994 and  underwent a esophagogastroduodenoscopy.  The employee was hospitalized in 1996 for chest pain and was hospitalized at United Hospital in June 1999 for recurrent pericarditis.  She was again treated in 1999 for ongoing esophageal and heart problems.

While working at Edelweiss, the employee participated in a diabetic study.  Following an abnormal EKG test, the employee saw her physician on February 14, 2005, and was referred for an angiogram which occurred on February 16, 2005, at Methodist Hospital.  The employee was admitted to the hospital where she underwent cardiac bypass surgery on February 17, 2005.  Following surgery, the employee remained hospitalized at Methodist Hospital for approximately six weeks in the intensive care unit.  A sputum test on February 25, 2005, revealed the employee was colonized with MRSA.  On March 28, 2005, the employee was transferred to United Hospital where it was noted she had a sternal wound draining purulent material that was cultured and found to contain MRSA.

Dr. Gary Kravitz, an infectious disease specialist, began treating the employee in March 2005.  The doctor reported the employee’s hospital course was complicated by adult respiratory distress syndrome as a complication of her surgery and infection, and she was on a ventilator for three weeks.  In addition, the employee developed problems with dysphagia and swallowing difficulties and severe depression requiring intensive psychiatric intervention.  Further, the employee’s underlying type one diabetes was volatile during the employee’s hospitalization.  The employee was discharged from United Hospital on May 18 to a nursing home where she completed an additional month of vancomycin therapy.  On June 26, 2005, the employee was readmitted to the hospital because of persistent upper sternal pain.  CT and MRI scans showed evidence of chronic osteomyelitis involving the sternoclavicular joints which required debridement.

Three medical doctors provided expert testimony in this case: Dr. Gary Kravitz, Dr. Christian Schrock and Dr. Jeffrey Mandel.  The doctors provided essentially consistent testimony regarding the history of Staphylococcus aureus and its evolution.  Staphylococcus aureus  or staph, is a bacteria that can cause serious infections in humans.  After penicillin was developed, all staph infections were treated with it.  By the 1970's however, certain strains of staph developed that were resistant to penicillin because the bacteria developed an enzyme that rendered the penicillin ineffective.  The medical community responded by developing types of synthetic penicillin that worked in the presence of the enzyme including methicillin, nafcillin, and oxycillin.  More recently, staph bacteria have developed resistence to the synthetic penicillins.  The common name for this condition is Methicillin resistence.  If the resistence is to Staphylococcus aureus, the condition is referred to as Methicillin-resistant Staphylococcus aureus or MRSA.  The original form of MRSA was found in the health care setting and the medical community refers to this as hospital-acquired MRSA or HA-MRSA.  More recently, a new strain of MRSA has developed called community-acquired MRSA or CA-MRSA which is a different strain adapted for transmission within the general population.  Not every person exposed to MRSA develops an infection.  Some persons become carriers of the organism without symptoms.  Risk factors for acquiring an infection include diabetes.

Dr. Kravitz testified by deposition and stated 80% of his practice involves seriously ill patients in a hospital setting with either community-acquired or hospital-acquired infections.  The doctor stated that HA-MRSA is highly associated with being a patient or working in the health care system whereas CA-MRSA is associated with congregate living situations such as prisons or associated with athletic teams.  Dr. Kravitz testified CA-MRSA is a more aggressive organism that tends to cause skin and soft tissue infections.  HA-MRSA causes blood stream infections, wound infections, urine infections, and is deeply entrenched in the health care system.  Dr. Kravitz testified a person becomes exposed to MRSA through touching the skin or open wound of an infected person, from the inanimate environment of an infected person or from the air, such as when an infected person sneezes or otherwise disseminates droplets into the air.  The person becomes colonized when the staph bacteria adheres to specific sites on the body, particularly the nose.  Dr. Kravitz stated the duration of an HA-MRSA colonization varies from a few days or weeks to several years and the median length of colonization was 40 months.  He testified health care workers are at an increased risk of colonization, especially those providing direct patient care.

Dr. Kravitz testified the employee had several diagnoses, but the one he dealt with primarily was a chronic sternal wound infection which he described as an infection of the sternum and adjacent cartilage caused by HA-MRSA.  Dr. Kravitz opined the employee’s risk of MRSA infection was very high because she dealt exclusively with chronically ill patients in a home care setting.  The doctor testified the medical literature showed the vast preponderance of MRSA infections were due to bacteria which colonized the patient prior to the hospital admission.  Dr. Kravitz concluded the employee did not acquire her MRSA while she was at Methodist Hospital.  Rather, in Dr. Kravitz’s opinion,  the employee’s MRSA colonization infection occurred as the result of her exposures to the bacteria at work which she brought with her to the hospital which then resulted in a post-operative infection.  Because the employee’s exposure at Edelweiss was more proximate in time to her hospital admission, the doctor opined it was more likely the employee developed her MRSA as a result of her exposure working for Edelweiss.

Dr. Christian Schrock, an infectious disease specialist, examined the employee on behalf of Accurate Home Care and its insurer and testified by deposition.  The doctor acknowledged the two types of MRSA, hospital and community acquired, but stated there was considerable overlap and the distinction between the two was becoming blurred and difficult to distinguish.  Dr. Schrock opined the employee’s exposure to her patients while working for Accurate Home Care was not a substantial contributing cause of her MRSA infection.  The doctor based this opinion on the fact that no culture was taken of the employee at the time of her admission to the hospital, so there was no proof she was colonized at that time.  Further, the doctor stated the length of time between the employee’s work for Accurate and her admission to the hospital eliminated that exposure as a reasonable source for the infection.  Rather, the doctor opined it was much more likely the employee acquired the MRSA infection after her admission to the hospital.

Dr. Jeffrey H. Mandel, an occupational medicine and epidemiology consultant, reviewed the employee’s medical records, the medical literature regarding MRSA, and hypothetical questions from the attorney for Edelweiss and prepared a medical report.  The doctor diagnosed osteomyelitis of the sternum caused by MRSA.  Dr. Mandel stated MRSA is a common infection within the health care industry occurring at high rates within hospitals and nursing facilities and in a lesser degree in the general community with a ratio of approximately 10 to 1.  The doctor stated the employee was predisposed to getting MRSA because of her underlying health conditions, but opined the precise origin of her infection could not be identified.  Absent a culture in advance of the employee’s heart surgery, Dr. Mandel stated it was difficult to determine whether she was colonized from her work at Edelweiss, but opined it was more likely than not that the employee’s MRSA originated from a hospital or nursing facility.

The employee’s claim petition seeking workers’ compensation benefits for an occupational disease in the nature of a MRSA infection was tried before a compensation judge at the Office of Administration Hearings.  In a Findings and Order, the compensation judge found that approximately 30% of the population is MRSA colonized at any given time and that health care workers have a higher rate of colonization than the general population.  The compensation judge further found:

The employee contends the compensation judge’s finding, that at any time 30% of the population is MRSA colonized, is incorrect.  In an article entitled “A Simple Guide to MRSA,” the following statement appears: “About 30% of the general population are colonized by S. aureus.”  (Pet. Ex. K, Ex. 5 at 2.)  This statement, the employee asserts, refers not to MRSA but to general staph infections.  In his article, “Epidemiology and clinical manifestations of methicillin-resistant Staphylococcus aureus infection to adults,” Dr. John M. Boyce states,

The compensation judge specifically found that 30% of the population at any given time is colonized with MRSA.  In her memorandum, the compensation judge stated:

In Dozier v. Control Data Corp., 44 W.C.D. 246 (W.C.C.A. 1990), the compensation judge rejected the opinion of one of the medical experts based upon a misreading of the doctor’s testimony.  In light of the compensation judge’s apparent misperception of the testimony, this court remanded the case to the judge for reconsideration.  In Hollister v. Aslesens, 472 N.W.2d 871, 45 W.C.D. 23 (Mem. Op., Minn. 1991), the issue was whether the employee’s personal injury was a substantial contributing cause to a subsequent permanent loss of function related to multiple sclerosis.  The Supreme Court concluded the compensation judge decided the case on a theory not addressed by the parties and determined the case should be reversed and remanded to the compensation judge.  The court explained:

There is a significant difference between the rate of MRSA colonization in the community assumed by the compensation judge and the actual rate.  We cannot determine the extent to which this error influenced the compensation judge’s decision.  We note, however, the compensation judge made several references to this statistic in the findings and order and specifically cites the statistic as one of the bases for her decision.  It is logical to assume that the higher the rate of MRSA colonization in the community, the less the significance which might be attributed to the employee’s exposures at work.  We, therefore, conclude principles of fairness and the interests of justice require the compensation judge to reconsider the case.  The compensation judge’s findings of fact are vacated and the matter is remanded to the compensation judge for further findings.