cefquinome and Streptococcal-Infections

The objectives of the present study were to evaluate the efficacy of intra-mammary-administered cefquinome for the treatment of sub-clinical mastitis in lactating dairy cows and to determine if extended therapy would enhance treatment efficacy. Seventy-three Holstein dairy cows from a single farm with 150 infected quarters were enrolled in the study. Infected cows were allocated randomly to one of three treatment regimens: (1) conventional (standard) regimen: 75 mg of cefquinome administered three times at 16-h intervals (25 infected cows, 52 intra-mammary infections (IMI)), (2) extended regimen: 75 mg of cefquinome administered six times at 16-h intervals (26 infected cows, 58 IMI) and (3) negative untreated control group (22 cows, 40 IMI). Most IMI were caused by coagulase-negative staphylococci, streptococci other than Streptococcus agalactiae and coliforms. The overall bacteriological cure (BC) rates for sub-clinical IMI were 84.61%, 91.37% and 20% for the conventional, extended and the control groups, respectively, indicating a higher BC rate for the treated groups than the control group (P < 0.001). Significant differences in somatic cell count (SCC) were detected between the treated versus the control group (P < 0.001). No differences, concerning the BC rate or SCC, were observed between the extended and the conventional groups. Although fat and protein percentages increased in the treated groups, there were no significant differences in post-treatment milk production between the groups. Results of this study indicate that cefquinome therapy was effective in reducing SCC and eliminating sub-clinical IMI in lactating dairy cows, but extended therapy did not enhance treatment efficacy.

Topics: Animals; Anti-Bacterial Agents; Asymptomatic Infections; Cattle; Cell Count; Cephalosporins; Enterobacteriaceae; Enterobacteriaceae Infections; Female; Injections, Intradermal; Iran; Mammary Glands, Animal; Mastitis, Bovine; Staphylococcal Infections; Staphylococcus; Streptococcal Infections; Streptococcus; Time Factors

Streptococcus suis serotype 2 is an emerging zoonotic pathogen and causes severe disease in both pigs and human beings. Cefquinome (CEQ), a fourth-generation cephalosporin, exhibits broad-spectrum activity against Gram-positive bacteria such as S. suis. This study evaluated the in vitro and in vivo antimicrobial activities of CEQ against four strains of S. suis serotype 2 in a murine neutropenic thigh infection model. We investigated the effect of varied inoculum sizes (10(6) to 10(8) CFU/thigh) on the pharmacokinetic (PK)/pharmacodynamic (PD) indices and magnitudes of a particular PK/PD index or dose required for efficacy. Dose fractionation studies included total CEQ doses ranging from 0.625 to 640 mg/kg/24 h. Data were analyzed via a maximum effect (Emax) model using nonlinear regression. The PK/PD studies demonstrated that the percentage of time that serum drug levels were above the MIC of free drug (%ƒT>MIC) in a 24-h dosing interval was the primary index driving the efficacy of both inoculum sizes (R(2) = 91% and R(2) = 63%). CEQ doses of 2.5 and 40 mg/kg body weight produced prolonged postantibiotic effects (PAEs) of 2.45 to 8.55 h. Inoculum sizes had a significant influence on CEQ efficacy. Compared to the CEQ exposure and dosages in tests using standard inocula, a 4-fold dose (P = 0.006) and a 2-fold exposure time (P = 0.01) were required for a 1-log kill using large inocula of 10(8) CFU/thigh.

Topics: Animals; Anti-Bacterial Agents; Cephalosporins; Disease Models, Animal; Dose-Response Relationship, Drug; Female; Mice, Inbred ICR; Microbial Sensitivity Tests; Neutropenia; Streptococcal Infections; Streptococcus suis; Thigh