Injections are given every 48 hours or until the pigs have recovered, thus cutting down on expensive labour and making it particularly convenient to use, especially in the finishing house. High initial blood levels, just after injection, will increase the killing rate of the antibiotic on the bacteria, giving it a quick initial response, which is essential for acute infections such as A. pleuropneumoniae. Blood levels stay above the MIC 90%s of the major bacteria, A. pleuropneumoniae, P. multocida and H. parasuis for 48 hours, giving a prolonged active inhibition of and protection from the bacteria enabling the body's defences to clear the infection. (See Graph 1)
Graph 1. Levels of Nuflor in blood (plasma) compared with MICs
(Voorspoels and others, 1999)
The activity of Nuflor was compared with a number of other antimicrobials and their activity against A. pleuropneumoniae, which can be the most severe form of bacterial pneumonia.
Table 2. Antimicrobial activity (µg/ml) against A. pleuropneumoniae (89 isolates)
|
Antimicrobial |
MIC 50% |
MIC 90% |
MIC Range |
|
Nuflor |
0.25 |
0.5 |
0.06-0.5 |
|
Tetracycline |
16.0 |
32.0 |
0.12-64.0 |
|
Penicillin |
0.5 |
32.0 |
0.12-64.0 |
|
Ceftiofur |
0.03 |
0.03 |
0.03-0.06 |
|
Enrofloxacin |
0.03 |
0.03 |
0.03-0.06 |
|
Tilmicosin |
2.0 |
4.0 |
0.12-4.0 |
|
Spectinomycin |
8.0 |
16.0 |
2.0-64.0 |
|
Trimethoprim/sulpha |
0.06 |
0.06 |
0.06-1.0 |
In this study there is resistance, which is quite marked, against tetracycline and also penicillin, two commonly used injectables, whilst the other antimicrobials such as ceftiofur, enrofloxacin, trimethoprim/sulpha are still active but have to be used on a daily basis rather than every two days like Nuflor.
In a series of field trials with mixed pneumonias (See table 1) Nuflor, given at 15mg/kg (1ml/20kg bodyweight) twice at 48 hours intervals, reduced the mortality of pigs dramatically from 7% to 0.7% and had a 72% recovery rate in comparison with control pigs that were severely affected.
Graph 2. Pneumonia field trial results with Nuflor in 540 pigs with mixed infections
(Zolynas and others, 2003)
In about 30% of cases, a transient anal reddening or inflammation and rectal eversion may be noted and an increase of soft to loose faeces may occur. These are transient and do not require additional treatment and do not interfere with the efficacy of the product.
It is important to continue to develop new antimicrobials for use in pig medicine and it is especially significant to have a new addition such as Nuflor to combat complex respiratory infections that we frequently encounter today.
References:
Salmon, S., Portis, E. and Lindeman, C. (2003) Minimum inhibitory concentrations for ceftiofur and comparator antimicrobial agents against bacterial pathogens of swine.
Proceedings of the AASV meeting, Orlando, USA, pp 235-239
Voorspoels, J., D'Haese, E., De Craene, B.A. and others (1999) Pharmacokinetics of florfenicol after treatment of pigs with single oral or intramuscular doses or with medicated feed for three days.
Veterinary Record, 145, 397-399
Zolynas, R., Cao, J. and Simmons, R. (2003) Evaluation of the efficacy and safety of Nuflor injectable solution (15mg/kg twice 48hours apart) in the treatment of swine respiratory disease (SRD).
Proceedings of the AASV meeting, Orlando, USA, pp 211-214