Table 2.

Representative bacterial isolates that inactivate or degrade ceftiofur and ceftriaxone

IsolateIdentification% drug remaining
CeftiofurCeftriaxone
CYPAaDCAbCYPADCA
11-024Arcanobacterium bernardiae7091NTNT
11-016Escherichia coli60100NTcNT
11-018Escherichia coli201003044
11-021Escherichia coli4892NTNT
03-040Escherichia coli6082NTNT
03-096Escherichia coli90100NTNT
03-107Escherichia coli90100NTNT
03-113Escherichia coli60100NTNT
03-115Escherichia coli5099NTNT
04-024Escherichia coli15636043
04-059Escherichia coli20754053
04-066Escherichia coli22965038
04-071Escherichia coli22846351
04-109Escherichia coli22763357
04-143Proteus mirabilis22854056
11-025Sphingomonas paucimobilis4552NTNT
11-027Sphingomonas paucimobilis45100NTNT
04-020Bacteroides fragilis20506733
04-043Bacteroides fragilis10645383
04-021Bacteroides helcogenes0275347
04-098Bacteroides ovatus20349375
04-093Bacteroides sp.0181218
04-086Bacteroides stercoris0665038
04-092Bacteroides stercoris01905
04-042Bacteroides suis2036074
04-055Bacteroides suis02253100
04-049Bacteroides thetaiotaomicron0.05434073
04-036Bacteroides uniformis10474247
03-041Desulfovibrio vulgaris0226722
03-117Obligate Gram-negative rod85100NTNT
03-013Eubacterium biforme10428742
03-100Eubacterium budayi85100NTNT
04-076Hallella seregens38446369
04-017Actinomyces howelli80100NTNT
04-124Actinomyces sp.80100NTNT
P-41Bacillus cereus0000
P-42Bacillus cereus0000
11-022Bacillus cereus00300
11-019Bacillus mycoides033544
03-023Bacillus mycoides0123012
03-044Bacillus mycoides0152735
03-046Bacillus mycoides40172730
03-008Enterococcus casseliflavus5044NTNT
03-106Enterococcus casseliflavus85100NTNT
03-119Enterococcus casseliflavus60100NTNT
03-077Facultative Gram-positive coccus85100NTNT
03-024Paenibacillus alvei7072NTNT
03-004Streptococcus bovis7081NTNT
03-042Streptococcus bovis5036NTNT
03-090Streptococcus bovis85100NTNT
03-121Streptococcus bovis60100NTNT
04-080Streptococcus suis20596349
03-001Streptococcus sp.7068NTNT
03-088Abiotrophia defectiva90100NTNT
03-126Bifidobacterium breve5043NTNT
03-078Clostridium absonum90100NTNT
03-080Clostridium absonum90100NTNT
03-063Clostridium cellobioparum85100NTNT
04-008Clostridium cocleatum20375027
04-127Clostridium perfringens60100NTNT
03-129Clostridium sartagoformum85100NTNT
03-124Clostridium scatalogenes90100NTNT
03-049Clostridium sp.510070100
03-110Clostridium sp.0418041
03-127Clostridium sp.5066NTNT
03-097Clostridium sporogenes85100NTNT
04-018Lactobacillus hamsteri8985054
03-091Obligate Gram-positive rod8074NTNT
03-104Obligate Gram-positive rod85100NTNT
03-109Obligate Gram-positive rod85100NTNT
03-120Obligate Gram-positive rod85100NTNT
  • a CYPA, cylinder-plate assay, which is a biological assay that measures inactivation and degradation of the drug. Percentages of activities of 1 μg/ml ceftiofur or 30 μg/ml ceftriaxone remaining after 6 h of anaerobic incubation at 35°C in overnight cultures of bacteria grown in brucella broth supplemented with vitamin K and hemin.

  • b DCA, desfuroylceftiofur acetate or desthiotriazinedione ceftriaxone acetate assay, which uses HPLC-MS peak areas to quantify the mass of intact drug left after 6 h of degradation.

  • c NT, not tested. Most weak ceftiofur degraders were not further analyzed for ceftriaxone degradation.