Magazine article Drug Topics

Antimicrobial Resistance among Community Pathogens

Magazine article Drug Topics

Antimicrobial Resistance among Community Pathogens

Article excerpt

An ongoing CE program of The University of Florida College of Pharmacy and DRUG TOPICS

The emergence of strains of microorganisms that are resistant to commonly used anti-infectives has become a global issue. Traditionally considered to be a hospital problem, antimicrobial resistance is now affecting pathogens in the community setting. When penicillin was introduced in the 1940s, some clinicians thought that they had won the battle against bacteria, but the reality is that only two pathogens remain routinely susceptible to penicillin: Streptococcus pyogenes, the microbial etiology of strep throat and certain skin infections, and Treponema pallidum, the microorganism that causes syphilis. Methicillin-resistant Staphylococcus aureus (MRSA) left the hospital a decade ago, penicillin-resistant Streptococcus pneumoniae (PRP) have spread widely, and there have already been reports of extended-spectrum beta-lactamase (ESBL)-producing Escherichia colt in the community. The alarming increase in antimicrobial resistance in the face of a drastic decline in the development of new antimicrobial agents may lead to a public health crisis. In the United States, healthcare costs associated with multi-drug resistance have been estimated to be several billion dollars. In addition to an increased cost of treatment, antimicrobial resistance is associated with a heightened risk of treatment failure and greater patient morbidity and mortality. This article reviews the mechanisms of antimicrobial resistance, highlights important microbial pathogens found in the community setting, discusses antimicrobial options for the treatment of resistant pathogens, and provides strategies to reduce antibiotic resistance.

Drivers of resistance in the community

Overuse and inappropriate use of antimicrobials have contributed to the development of resistance in both the inpatient and outpatient settings. As opposed to the inpatient setting, culture and susceptibility methods are often not readily available in the community setting. Thus, clinicians tend to prescribe broad-spectrum empiric antibiotic agents for entire courses of therapy and often do not de-escalate therapy. The impact of the empiric use of broad-spectrum agents was analyzed in one study that reviewed the appropriateness of fluoroquinolone use in the emergency department setting. This study analyzed 100 consecutive emergency department patients who received a fluoroquinolone and were subsequently discharged. Some 81% of patients received a fluoroquinolone despite the fact that it was not considered to be a first-line option or researchers could not determine a need for an antibiotic (i.e., there was no evidence of infection). Even more alarming, of the 19 patients who appropriately received a fluoroquinolone based on indication, only one patient received the appropriate dose for the adequate duration of time.

Additionally, antibiotics are frequently prescribed to treat infections that are not always caused by bacteria. This may be due to knowledge gaps among prescribers or patient attitudes and expectations from an office visit. In a survey of 28,787 office visits to 1529 physicians, antibiotics were prescribed to 51% of patients with colds, 52% of patients with acute upper respiratory infections, and 66% of patients with bronchitis. These are infectious diseases that usually have a viral etiology, and thus would not necessarily require antibiotic therapy. The use of antibiotics to treat viral infections is detrimental to the body's normal flora and may select for resistant pathogens.

In addition to factors previously stated, the cost of antibiotic agents plays a role in the development of resistance. The relatively low cost of antibiotics, the availability of free antibiotics by certain retail chains, and the upcoming generic availability of more broad-spectrum agents may cause an increase in the inappropriate use of antimicrobials, ultimately causing an adverse impact on the resistance crisis. …

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