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Arresting drug-resistant organisms



Bad bugs are up to new tricks. Find out about emerging pathogens that resist antibiotics and learn how to subdue them.

Protect your vulnerable patients and yourself from emerging diseases that resist many antibiotics.



ANYONE WHO'S SICK or otherwise compromised is especially vulnerable to emerging infectious diseases caused by organisms that are either new or manifesting themselves in new ways. In this article, we'll look at several emerging diseases characterized by antibiotic resistance: community-acquired methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), vancomycin-resistant S. aureus (VRSA), and extended-spectrum beta–lactamase (ESBL)-producing organisms. Here's what you need to know to protect your patients and yourself.

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Community-acquired MRSA: Neighborhood bully

You're probably familiar with hospital-acquired MRSA, which causes ventilator-associated pneumonia, bacteremia associated with central lines, and other nosocomial infections. In contrast, community-acquired MRSA most often causes soft-tissue infections.

Hospital-acquired MRSA typically affects the chronically ill and elderly, but community-acquired MRSA tends to infect younger people. The good news is that although it's resistant to methicillin, it's sensitive to other antibiotics.

Persons at higher risk include children in day care, amateur and professional athletes (who are in close contact and may share equipment), users of injected recreational drugs, men who have sex with men, and prisoners. It's transmitted primarily via direct physical contact, not through respiratory droplets. Transmission via indirect contact (for example, contact with contaminated door handles, eating utensils, and furniture) isn't likely. But in institutions or households, the disease may be transmitted via clothes and linens that are grossly contaminated with drainage from an infected wound. Athletes' sharing of soap and towels is another risk factor.

A soft-tissue MRSA infection often involves abscesses, furuncles, or cellulitis. Initially, the patient may assume he was bitten by a spider.

Although hospital-acquired MRSA may respond only to vancomycin, community-acquired MRSA is sensitive to many more antibiotics. After an infected wound is irrigated and debrided, the patient may be prescribed tetracycline, doxycycline, clindamycin, or sulfamethoxazole-trimethoprim. Besides methicillin, community-acquired MRSA is considered resistant to cephalexin, dicloxacillin, erythromycin, and quinolones.

To protect yourself and your patients, take contact precautions as recommended by the Centers for Disease Control and Prevention (CDC). (See Taking steps to stay safe) Teach your patient not to use topical antibiotics if new abscesses or cellulitis develop; new culture specimens will need to be obtained first. Ask him about his direct contacts (anyone he's touched or who has touched him), to identify others with the same signs and symptoms who may need treatment.

To help him prevent further disease transmission in the household, teach him to clean household surfaces with regular soap (not antimicrobial) and water and to wash linens and clothing with detergent and dry them in a dryer.

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VRE: First among resistant organisms

Enterococci were the first organisms to be found resistant to vancomycin. The morbidity and mortality rates for VRE are low. However, VRE occurs at higher rates in patients with MRSA. Researchers worry that treating MRSA with vancomycin has encouraged the development of vancomycin–resistant strains of S. aureus, which are rare.

In the hospital, VRE is dangerous to patients being treated with invasive devices, which increase infection risk, especially if their immune systems are compromised. However, although VRE can be found throughout an infected patient's room, the disease is spread by direct contact.

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S. aureus resistance: This VISA shouldn't go anywhere

As bacteria develop drug resistance, they evolve from sensitive to intermediate to resistant. Vancomycin intermediate S. aureus (VISA) and VRSA have recently been identified. Currently, vancomycin is the treatment of choice for strains of S. aureus that have developed resistance to methicillin (MRSA). This emerging resistance to vancomycin means that available antibiotics may become useless against these infections, which would be a serious development: Before antibiotics, S. aureus infections killed up to 40% of all patients undergoing major surgery.

Fortunately, neither VISA nor VRSA has been transmitted between patients to date. All patients known to have had VISA had a history of prolonged and recurrent vancomycin treatment, and all had the hospital strain of MRSA. Because VISA and VRSA evolved from MRSA, patients with VISA also are resistant to methicillin.

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ESBLs: Upping the antibiotic ante

Microorganisms that produce ESBL are resistant to extended-spectrum (or third-generation) cephalosporins such as ceftazidime, cefotaxime, and ceftriaxone, and monobactams such as aztreonam. The most common ESBL-producing organisms are the Gram-negative bacteria, typically Klebsiella species and Escherichia coli, although ESBL production has also been found in some strains of the Salmonella species, Proteus mirabilis, and Pseudomonas aeruginosa. These organisms don't cause more serious disease or a different manifestation of disease than their non-ESBL-producing counterparts. But the infections they cause are more difficult to treat because the organisms resist first-line antibiotics used to treat Gram-negative bacterial infections.

Patients at risk include those with intravenous or indwelling urinary catheters or gastrostomies, patients on mechanical ventilation, patients who've had previous antibiotic therapy or emergency abdominal surgery, patients with gastrointestinal colonization or severe illness, and those with long stays in the hospital or intensive care unit.

Most ESBL infections respond to a carbapenem antibiotic, such as imipenem or meropenem. If your patient has a Gram-negative bacterial infection, culture specimens should be taken and tested for ESBL production and sensitivity so that he receives an effective antibiotic.

ESBL-producing organisms can spread by direct and indirect contact. If you're caring for a patient with this type of infection, don't touch your eyes, nose, or mouth during patient care. Perform appropriate hand hygiene before and after giving care and before drinking or eating.

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Isolation tactics

A patient with an antibiotic-resistant bacteria should be placed in a private room or in a room with another patient with the same infection. Follow isolation precautions recommended by the CDC.

  • Don personal protective equipment before entering the room. Put on the gown first, then a mask or respirator (if needed because the patient has another illness such as tuberculosis), then goggles or face shield (if splashing of body fluids is possible), and finally gloves.
  • Change gloves if they tear or touch body fluids.
  • Remove your gloves and goggles (or face shield) and gown and perform hand hygiene before leaving the patient's room.
  • Remove the respirator outside the patient's room.
  • Follow infection control protocols for bagging and disposing of protective gear.
  • If possible, each patient should have dedicated equipment, such as a stethoscope, blood pressure cuff, and rectal thermometer. If equipment must be shared, thoroughly clean and disinfect it before using it on another patient.
  • Make sure that other staff members who enter the room understand and comply with these precautions. For more information, see “Getting the Most from your Personal Protective Gear,” Exposure Safety, in the December issue of Nursing2004.
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Supporting your patient

A patient who must be isolated is likely to be worried and depressed. Provide emotional support and encourage him to stay as engaged and active as his condition permits. Inform him about support services available from volunteers or the chaplain.

By understanding the newest trends in antibiotic resistance, you can help protect your patients and yourself from emerging diseases.

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Taking steps to stay safe

To reduce the risk of spreading antibiotic-resistant infections, follow these guidelines from the Centers for Disease Control and Prevention for contact precautions.

  • Practice meticulous hand hygiene. Patients, their families, and health care providers should wash their hands before eating and before and after patient contact. Using warm water and soap, scrub for 15 seconds, rinse with water, and dry your hands with a paper towel. If your hands aren't visibly soiled, you can use an alcohol-based hand rub instead of soap and water.
  • Use indwelling and I.V. catheters only when essential and remove them as soon as possible. Use proper insertion technique and follow catheter care protocols. If your patient has a central venous access device that hasn't been used in days, ask the health care provider if it can be removed. If your patient is incontinent, use a skin barrier cream and disposable incontinence products instead of an indwelling urinary catheter if possible.
  • Implement and follow an antibiotic protocol. To ensure prudent use of vancomycin and extended-spectrum cephalosporins, your facility should have an antibiotic surveillance team and guidelines for the proper use of antibiotics. Know which antibiotics are being used to treat which organisms and treat infection, not colonization. Colonization doesn't harm the patient, and treating it often leads to more resistant organisms. Treatment is rarely indicated for patients with positive cultures but no signs of infection (such as fever, erythema, or increased white blood cell count).
  • Place a patient with multidrug-resistant organisms in a private room or in a room with another patient who has the same organism.
  • To reduce the risk of transmitting organisms to other patients or to staff, disinfect surfaces in the patient's room—especially high-touch surfaces such as countertops, bed rails, and door handles—daily.
  • Follow standard precautions when handling and disposing of linen. No special precautions are needed for dishes, glasses, cups, or eating utensils; use disposable cups or plates only if ordered.

Rebecca Kjonegaard is an infection control practitioner at Sharp Grossmont Hospital in La Mesa, Calif. Frank Edward Myers III is manager of clinical epidemiology and safety at Scripps Mercy Hospital in San Diego, Calif.

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Centers for Disease Control and Prevention: Community-associated MRSA

Last accessed on May 2, 2005.

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