In vitro antimicrobial activity of nitrofurantoin against Escherichia coli and Staphylococcus pseudintermedius isolated from dogs and cats

TY - JOUR

T1 - In vitro antimicrobial activity of nitrofurantoin against Escherichia coli and Staphylococcus pseudintermedius isolated from dogs and cats

AU - Maaland, Marit Gaastra

AU - Guardabassi, Luca

PY - 2011/8/5

Y1 - 2011/8/5

N2 - Minimum inhibitory concentrations (MIC) of nitrofurantoin were determined by agar dilution in 269 canine and feline isolates of Escherichia coli and Staphylococcus pseudintermedius, two of the most common bacterial species associated with urinary tract infection (UTI) in small animals. The MIC90 for E. coli and S. pseudintermedius were 32 and 16μg/ml, respectively. All isolates, including multidrug-resistant strains of known genetic background, displayed MICs below the drug concentrations reported in canine urine following oral administration of nitrofurantoin. Preliminary data on mutant prevention concentration (MPC) and many years of nitrofurantoin usage in human medicine suggest that emergence of resistant mutants during treatment is not a critical issue for this drug. The study provides species-specific data on nitrofurantoin MIC distribution that can be used for setting dog- and cat-specific breakpoints. Although nitrofurantoin is not an appropriate first-line agent for empirical treatment of canine UTI due to toxicity and poor pharmacokinetic properties, it may be indicated for treatment of UTI caused by multidrug-resistant bacteria, which are otherwise difficult to treat using conventional veterinary antimicrobial agents.

AB - Minimum inhibitory concentrations (MIC) of nitrofurantoin were determined by agar dilution in 269 canine and feline isolates of Escherichia coli and Staphylococcus pseudintermedius, two of the most common bacterial species associated with urinary tract infection (UTI) in small animals. The MIC90 for E. coli and S. pseudintermedius were 32 and 16μg/ml, respectively. All isolates, including multidrug-resistant strains of known genetic background, displayed MICs below the drug concentrations reported in canine urine following oral administration of nitrofurantoin. Preliminary data on mutant prevention concentration (MPC) and many years of nitrofurantoin usage in human medicine suggest that emergence of resistant mutants during treatment is not a critical issue for this drug. The study provides species-specific data on nitrofurantoin MIC distribution that can be used for setting dog- and cat-specific breakpoints. Although nitrofurantoin is not an appropriate first-line agent for empirical treatment of canine UTI due to toxicity and poor pharmacokinetic properties, it may be indicated for treatment of UTI caused by multidrug-resistant bacteria, which are otherwise difficult to treat using conventional veterinary antimicrobial agents.

KW - Former LIFE faculty

KW - Veterinary medicine

KW - cystitis

KW - antibiotic resistance

KW - rational antibiotic use

U2 - 10.1016/j.vetmic.2011.03.009

DO - 10.1016/j.vetmic.2011.03.009

M3 - Journal article

C2 - 21482044

SN - 0378-1135

VL - 151

SP - 396

EP - 399

JO - Veterinary Microbiology

JF - Veterinary Microbiology

IS - 3-4

ER -