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Bacteria that Bite


July 2005

by Natalie Gutierrez

It was a hot summer afternoon in 2003. Lara Neitsch, 28, was enjoying a game of cards with friends in her backyard when she felt a sharp sting on her left knee. "I thought something had bitten me," she said. The red boil resembled two others that appeared on her body three weeks earlier. But what Neitsch thought were spider bites turned out to be far more toxic, and left her and her family caught in a web of illness and frustration for nearly six months.

Within a few days, the boil increased in size and became so painful that Neitsch had trouble walking. Her family physician prescribed Duricef, an antibiotic used to treat spider bites. But when the boil failed to heal after three rounds of antibiotics, and a fourth boil appeared on her left thigh, Neitsch became worried. Within a few weeks her husband, Brian; her son, Brian Jr., 4; and her daughter, Regan, 8, developed the same boils on their bodies. By that time, Neitsch had developed further complications, including an upper respiratory infection, fever and malaise. Concerned for her family’s health, Neitsch sought the help of infectious diseases expert Jan Patterson, M.D.
This scanning electron micrograph depicts a grouping of methicillin resistant Staphylococcus aureus (MRSA) bacteria.

Dr. Patterson is professor of medicine and pathology at the Health Science Center, director of hospital epidemiology for the University Health System and the South Texas Veterans Health Care System, and chief of medical services for the VA. With assistance from Ronald Stewart, M.D., who surgically drained and cultured Neitsch’s abscess, Dr. Patterson immediately diagnosed community-associated methicillin-resistant staphylococcus aureus (CA-MRSA).

Dr. Stewart is associate professor of surgery and director of trauma and emergency surgery for the Health Science Center and the University Health System.

According to the U.S. Centers for Disease Control and Prevention, staph bacteria are among the most common causes of skin infections in the United States and are commonly carried on the skin or in the nose of healthy people. One-fourth to one-third of Americans have them in the nose but have no resulting problems. Sometimes, however, they turn aggressive. When not treated properly, staph infections can poison the bloodstream or cause pneumonia.

MRSA is a type of staph that is resistant to many common antibiotics. In the past MRSA usually occurred most frequently in hospitals or nursing homes in patients with weakened immune systems. However, in the last five years health care providers have witnessed an increase in MRSA cases in healthy individuals in the general population, leading them to name this staph community-associated MRSA.

"CA-MRSA is a complex bacterium that carries a particularly toxic protein," Dr. Patterson said. "These bacteria contain genes that mediate antibiotic resistance, and a protein that makes them very aggressive and easily spread on the skin and underlying soft tissue. Although cases are on the rise, there have been few substantial studies on how CA-MRSA is treated in surgical settings."

Under the direction of Dan Dent, M.D., associate professor of surgery, and Dr. Patterson, Nabilla Porbandarwalla, second-year medical student, led the first epidemiological study of CA-MRSA in a surgical setting. What she discovered was disturbing. Of the more than 350 patients with CA-MRSA admitted to the emergency room at University Hospital, 71 percent had been administered antibiotics to which the CA-MRSA strains were not susceptible. Many of the patients were initially misdiagnosed as having an insect bite.

"By the time we were able to treat them properly, many of these patients’ infections had become more serious," Porbandarwalla said. "Some had abscesses two inches deep, others had respiratory complications and one patient nearly died." Porbandarwalla’s findings were so compelling, her study earned first-place honors at the American Medical Association’s Research Poster Award ceremony in Chicago last year. Her abstract was chosen from 88 posters submitted by students from medical schools across the country. Her work also earned the Dean James J. Young Alumni Association Award at the Health Science Center’s Medical Student Research Day.

One of Porbandarwalla’s and Dr. Patterson’s goals is to educate health care providers across the country regarding the proper diagnosis and treatment of CA-MRSA. Dr. Patterson recently met with representatives of the Texas Department of State Health Services to finalize health guidelines for the control and prevention of CA-MRSA. "We plan to begin in Texas by providing educational outreach to primary care providers. Nabilla’s study will definitely assist physicians in understanding and managing this problematic infection," she said.

Because a vaccine for CA-MRSA isn’t available to the general population, Dr. Patterson said awareness and education are the best defenses against contracting and spreading an infection. "Every health care provider should know what it is and how to properly treat it," Dr. Patterson said. "And everybody should know what to do to avoid spreading it."

It’s been about two years since Lara Neitsch and her family struggled with CA-MRSA. "I’m glad to know that CA-MRSA awareness is on the rise. Now that I know more about it, I’ll never look at what might look like a ‘bite’ the same way again. No one should."


What are MRSA and CA-MRSA?

  • MRSA is a type of staph that is resistant to many common antibiotics.
  • CA-MRSA bacteria carry a toxic protein making them aggressive and easily spread on the skin and underlying soft tissue.


    Suspicious Symptoms

  • A skin infection that may look like a spider bite, pimple or boil and can be red, swollen, painful, or have pus or other drainage.
  • More serous infections may cause pneumonia, bloodstream infections or surgical wound infections.


    How can I prevent a staph or MRSA skin infection?

  • Wash hands thoroughly with soap and water or use an alcohol-based sanitizer.
  • Keep cuts and scrapes clean and bandaged until healed.
  • Avoid contact with other people’s wounds or bandages.
  • Avoid sharing items such as towels or razors.

    Source: U.S. Centers for Disease Control and Prevention

    To view the Texas Department of State Health Services’ guidelines for the control and prevention of CA-MRSA, visit www.tdh.state.tx.us/ideas/antibiotic_resistance/overview/health_care/.





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