Fending off antimicrobial resistance is a battle of constant attack, research
Bacteria are becoming more and more resistant to the latest round of antibiotics created to fight them. The fear is that the organisms may eventually become so resistant to antibiotics that they will be able to kill patients without interference.
"This is already a reality," John Bosso, PharmD, professor of pharmaceutical sciences at the Medical University of South Carolina’s College of Pharmacy in Charleston, tells Drug Utilization Review. "With gram-positives, this is already a problem with Enterococcus and Staph aureus. With Enterococcus, we have the problem of vancomycin resistance as well as resistance to older agents. With Staphylococcus aureus there is a concern over rising MICs [minimum inhibitory concentrations]. Some isolates, while not yet resistant to vancomycin, have higher MICs."
Rising MICs can predict approaching drug resistance.
"Methicillin-resistant Staph aureus [MRSA] is more prevalent now and is no longer limited to hospital environments," Bosso says. "We’re seeing people not at risk enter the hospital with MRSA. Resistant gram-negative organisms include Pseudomonas, Klebsiella, and E. coli. These are becoming quite problematic. However, there are several actions that pharmacists can take to play an important role in helping prevent the widespread growth of this problem."
Educate your patients
"Pharmacists can educate patients about the non-necessity of using and abusing antibiotics for viral infections, especially respiratory infections. Physicians are all too often fueled to prescribe antibiotics by patient expectations that they’re not receiving good medical care unless they walk away from the physician’s office with a prescription."
Often, that prescription is completely unnecessary and only adds to the growing resistance problem, according to Bosso.
"Pharmacists who follow and advocate good infection-control procedures will help retard this growing problem," says Bosso. "The conventional wisdom of using the drug with the narrowest spectrum of activity is still an effective strategy."
The more pharmacists follow up on patient cultures and sensitivities, matching those lab findings to the appropriate antibiotic, the more they help. "Using the appropriate therapy is key," says Bosso. "That includes using the drug with the narrowest effective spectrum of activity, and being sure to provide adequate dosing. Underdosing adds to the problem of resistance too. Conversely, overextended duration of therapy also increases the resistance problem."
The careful matching of cultures and sensitivities to disease state to antibiotic is a balancing act that can be performed by pharmacists and that will have an effect not only on patient-specific outcomes, but on the overall public health.
"There are tricks to correctly creating and using antibiograms, but their proper use can be very effective in helping slow the growth of resistant organisms in an institution," says Bosso.
He recommends quarterly updates of antibiogram information. As the antibiograms of an institution are followed over time, emerging resistance trends can be detected in their early stages and appropriate changes made in antibiotic prescribing habits before the resistance problem gets out of hand. Bosso adds that antibiograms can be problematic because they represent pooled data — they reflect all the isolates tested by the institution’s lab. It is valuable to be able to know if the data represent inpatient vs. outpatient isolates, or a combination of the two. Other valuable information is whether data represent urine or non-urine isolates, or both. Additionally, data representing isolates found hospitalwide may well be different than data representing isolates just from the burn unit or the medical intensive care unit.
An ounce of prevention
"Prevention is always the most desirable plan," says Bosso. Carefully following aseptic techniques is important for anyone in the clinical setting, not just pharmacists.
Employing proper skin preparation techniques for vascular procedures and surgery is another way to prevent infections, often septicemia. Chlorhexidine gluconate 2% solution in 70% isopropyl alcohol (ChloraPrep) was recently approved by the FDA in a 3 mL sponge applicator to be used during skin preparation.
"ChloraPrep is at least equivalent to currently available products for skin preparation at 10 minutes. But ChloraPrep also exhibits a cumulative effect that extends to five days," Rebecca Minion, vice president of Strategic Planning for Medi-Flex Hospital Products, tells DUR.
The formulation appears to be both bactericidal and bacteriostatic. For those organisms it does not kill, it exhibits a proven static effect. Other formulations of chlorhexidine gluconate (CHG) have been in use for approximately 30 years with proven efficacy against bacterial organisms. When used as part of the aseptic technique (for handwashing), CHG appears to be better tolerated than other preparations. Minion comments that in one handwashing study, 50% of staff who used povidone iodine had severe skin irritation. By comparison, only 38% of those who used CHG reported mild irritation.
New labeling would emphasize resistance
The Food and Drug Administration (FDA) has proposed labeling requirements for systemic antibacterial drug products to address the growing problem of drug-resistant organisms. The FDA encourages physicians to prescribe systemic antibiotics only in situations where truly necessary and to counsel patients on the importance of taking prescribed antibiotics precisely as directed.
Under this proposal, revised labeling would address these reminders to physicians:
• Antibacterial drugs should only be used in situations where a bacterial infection is either proved or strongly suspected. Antibacterials do not treat viral infections.
• The type of bacteria involved in an illness and its antimicrobial susceptibility pattern should be used to direct the initial choice of an antibiotic.
• Antimicrobial therapy should be modified once microbiologic results are available.
• Patients should be counseled about the proper use of antibiotics and the importance of taking them only as directed.
(See www.fda.gov/ for more information. Click on the search button at the bottom of the page, then type these words: labeling requirements for systemic antibacterial drug products. Click on the circle that says "All of the words." When the new page appears, click on "Search by date." Then choose article No. 2.)
Newer, stronger antibiotics, such as the ketolides, continue to be developed that have not led to resistance problems yet. Organisms become stronger the more they fight. Once they learn the killing mechanism of an antibiotic, they are able to adapt to that mechanism, changing themselves enough to be resistant to the old pharmaceutical weaponry.
Sources
• John Bosso, PharmD, Professor of Pharmaceutical Sciences, MUSC College of Pharmacy, 150 Ashley Ave., RT Annex, Charleston, SC 29425. Telephone: (843) 792-8501.
• Rebecca Minion, Vice President, Strategic Planning, Medi-Flex Hospital Products Inc., 8717 W 110th St., Overland Park, KS 66210. Telephone: (913) 451-0880.
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