Frequency of Resistance in Obligate Anaerobic Bacteria Isolated from Dogs, Cats, and Horses to Antimicrobial Agents

Abstract

cClinical specimens from dogs, cats, and horses were examined for the presence of obligate anaerobic bacteria. Of 4,018 specimens cultured, 368 yielded 606 isolates of obligate anaerobic bacteria (248 from dogs, 50 from cats, and 308 from horses). There were 100 specimens from 94 animals from which only anaerobes were isolated (25 dogs, 8 cats, and 61 horses). The most common sites tested were abdominal fluid (dogs and cats) and intestinal contents (horses). The most common microorganism isolated from dogs, cats, and horses was Clostridium perfringens (75, 13, and101 isolates, respectively). The MICs of amoxicillin with clavulanate, ampicillin, chloramphenicol, metronidazole, and penicillin were determined using a gradient endpoint method for anaerobes. Isolates collected at necropsy were not tested for antimicrobial susceptibility unless so requested by the clinician. There were 1/145 isolates tested that were resistant to amoxicillin-clavulanate (resistance breakpoint > 16/8 g/ml), 7/77 isolates tested were resistant to ampicillin (resistance breakpoint > 2 g/ml), 4/242 isolates tested were resistant to chloramphenicol (resistance breakpoint > 32 g/ml), 12/158 isolates tested were resistant to clindamycin (resistance breakpoint > 8 g/ml), 10/247 isolates tested were resistant to metronidazole (resistance breakpoint > 32 g/ml), and 54/243 isolates tested were resistant to penicillin (resistance breakpoint > 2 g/ml). These data suggest that anaerobes are generally susceptible to antimicrobial drugs in vitro.

Pharmacokinetics of chloramphenicol base in horses and comparison to compounded formulations

“…A number of anaerobes are susceptible to low concentrations of chloramphenicol as well, including Porphryomonas spp (MIC = 0.38–0.5 μg/ml, n = 2 isolates) and Prevotella spp (MIC = 0.38–1.5 μg/ml, n = 8) , and most Peptostreptococcus spp (MIC = 0.38–2 μg/ml n = 14, with one isolate having an MIC of 4 μg/ml) and Fusobacterium spp . isolates (0.064–2 μg/ml n = 12, with one isolate having an MIC of 8 μg/ml), and they would be considered susceptible to attainable concentrations in horses (Lawhon, Taylor, & Fajt, ). A report of the antimicrobial susceptibility of two Lawsonia intracellularis isolates demonstrated intracellular MIC values for chloramphenicol ≤2 μg/mL, and this suggests that chloramphenicol could be used to treat this infection (Pereira et al, ).…”

Antimicrobial Susceptibility of Bacteroides spp. From Clinical Samples From Horses

“…Other involvements of Bacteroides spp. in horses include endometritis [5], abscesses [6], peritonitis, septic arthritis [4], diarrhea in foals [7], wounds [1,6] and keratitis [8]. Much research has been done on Bacteroides spp.…”

“…They are important pathogens involved in infections in horses, comprising as much as 8% of anaerobic bacterial infections [1]. Examples of infections involving Bacteroides spp.…”

Clostridium perfringens: a review of the disease in pigs, horses and broiler chickens

“…In contrast, resistance to macrolides (commonly erythromycin) and oxytetracycline is common (SILVA et al, 2013;LAWHON et al, 2013). It is also important to remember that, despite the high susceptibility, some studies suggest that exposure to gentamicin and penicillin could predispose equines to C. perfringens type A infection (HERHOLZ et al, 1999;VILEI et al, 2005;HAZLETT et al, 2011) Similar to the reports for swine, the vaccination of mares with beta toxoid to prevent type-C enterotoxemia in foals is common in some countries, although studies regarding the immune response of equines to this or other clostridial antigens are rare (TIMONEY et al, 2005).…”