MD Conference Express ICAAC 2011 - (Page 19)
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Preventing Resistance – The Role of Optimized Dosing
Written by Rita Buckley
Resistance in the Gut The rapid emergence of antibiotic resistance is a major public health concern [Zhang L et al. Appl Environ Microbiol 2011]. Johan W. Mouton, MD, Nijmegen Institute for Infection, Inflammation & Immunity, Nijmegen, The Netherlands, discussed five questions of resistant bacteria in the gut: • Their possible presence without antibiotic exposure • Whether there is selection of resistant gut bacteria during antimicrobial exposure • Whether there is selection of resistance during systemic treatment for other infections • Whether it is possible to avoid or minimize selection • How optimization of treatment relates to selection of resistance in the gut Data suggest that early development of antibiotic resistance in human gut microbiota is independent of an infant’s exposure to antibiotics but is likely to be affected by exposure to maternal and environmental microbes during and after delivery. The population of foodborne antibiotic-resistant bacteria is also significantly amplified within the host, even in the absence of antibiotic-selective pressure [Zhang L et al. Appl Environ Microbiol 2011]. Prof. Mouton cited a study in which 2 of 20 children with no known antibiotic exposure, living in a very remote Senegalese village, were fecal carriers of a multiresistant Escherichia coli clone that produced CTX-M-15 [Ruppe E et al. Antimicrob Agents Chemother 2009], strongly suggesting that the pC15-1a multidrug-resistant region can persist in the intestinal flora in the absence of significant selective pressure, at least that we know of. Based on a report by de Smet et al. [Lancet Infect Dis 2011], Prof. Mouton justified the widespread use of selective digestive tract decontamination in intensive care units with low levels of antibiotic resistance. Prof. Mouton presented an extensive analysis of an experimental study that looked at the effects and duration of antimicrobial treatment for pneumonia in selecting resistant microorganisms in the gut [Goessens WH et al. JAC 2007]. This showed that the more frequent the dosing regimen, the higher the propensity for selecting resistant bacteria. Emergence of resistance is dependent on dose (inverse U shape), duration of therapy, and dosing regimen. For the first three questions that were posed, Prof. Mouton answered “yes;” “perhaps” to the fourth; and “not good” to the fifth. Resistance in a Dynamic Model Didier Guillemot, MD, Institut Pasteur/Univ. Versailles Saint Quentin/Inserm, Paris, France, discussed the impact of antibiotic dose on resistance selection in the community. His findings were based on a dynamic model of Streptococcus pneumoniae. His presentation covered β-lactam doses and pneumococci susceptibility, accounting for β-lactam doses. From a public health point of view, antibiotics do more to increase the clearance of susceptible bacteria than the acquisition of a new mechanism or resistant strain. Prof. Guillemot noted that much is known about the relation between S. pneumoniae, antibiotics, and resistance, but not at the population level.
Peer-Reviewed Highlights from the
51st ICAAC
Official Peer-Reviewed Highlights from the 51st ICAAC
19
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Table of Contents for the Digital Edition of MD Conference Express ICAAC 2011
MD Conference Express ICAAC 2011
Contents
Infectious Disease Genomics
Emerging Resistance Among Gram-Negative Pathogens
Procalcitonin-Guided Antibiotic Therapy In Patients with Lower Respiratory Tract Infections
Combination Therapy with Flucytosine Improves Survival in AIDS-Related Cryptococcal Meningitis
CXA-201 Effective Against Common ICU Pathogens
Tigecycline Plus Standard Therapy Is More Effective For Treating Infections in Febrile Neutropenic Cancer Patients
Interventions Aimed at Reducing MRSA BSIs Led to Decreased Rates of Nosocomial MSSA BSIs
Is the Effectiveness of aP Vaccine in Pre-Adolescents Insufficient?
TMC435 Effective in the Treatment of HCV Genotype 1 Infection
HIV
Vaccines
Antibiotic Resistance
Drug Discovery
The Conundrum of MDR TB and Combination Therapy
New Drugs to Treat MDR Pathogens
Immunizations in Reproductive Health
Why Can’t Microbes Just Get Along?
The Role of Adjunctive Steroids in the Treatment of Bacterial Meningitis
Human and Animal Viruses Share “One World” and Emerging Zoonotic Infections Continue to Threaten
MD Conference Express ICAAC 2011
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