الفهرس 
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Abstract
Quinolones are a group of synthetic antibacterial agents which has been recently used in animal medicine, among this group come norfloxacin as one of the most recently used drug which have an excellent in-vivo activity. Hence, the present study was aimed to evaluate the in-vitro activity as well as in-vivo antibacterial and pharmacological
profile of norfloxacin.
For this purpose, 240 apparently healthy chicks were used and classified into 3 main groups and the results are summarized as follows:
Determination of MIC:
The minimal inhibitory concentrations (MIC) of norfloxacin against freshly isolated different types of microorganisms were 0.01 pg/m1 for Escherichia coli and Salmonella, 0.35 p.g/m1 for Coryza, 0.45 pg/m1 for Pseudomonas aeruginosa, 0.5 pg/m1 for Bacillus subtilis, 0.70 p.g/ml for Staphylococcus aureus and 2.0 p.g/m1 (2 x 108 CFU) for
Mycoplasma gallisepticurn.
In vitro activity:
In-vitro activity of norfloxacin as a chemotherapeutic agent compared with seven commonly used antibiotics against 5 microorganisms (Staph. aureus, Bacillus subtilis; Coryza; P. aeruginosa and Escherichia coli) demonstrates that norfloxacin is the most potent antibiotic used for Staph. aureus, Bacillus subtilis and Coryza. It is potent also against Mycoplasma gallisepticum.
Blood concentration level:
Blood concentration level of norfloxacin in healthy and infected chickens after single intramuscular injection of 2.5 mg/kg b.wt. demonstrates that norfloxacin reached its maximum level in serum after 2.5 hours in both healthy and artificially E. coli infected chickens and then significantly declined till completely disappeared from serum after 36 and 33 hours in healthy and diseased chickens respectively. Rising and depletion rate of serum norfloxacin concentrations in healthy as well as infected chickens showed that norfloxacin concentration reached its maximum level in infected chickens faster than in healthy ones.
Determination of norfloxacin residues:
Following intramuscular injection of norfloxacin in a dose level of 2.5 mg/kg b.wt. for 5 consecutive days in healthy chicken, the liver contained the highest residue concentration which remained for longer periods of time where it completely disappeared after about 4 days from the last dose followed by lung, muscles and kidney then heart and gizzard. Norfloxacin reached maximum level after 8 hours in liver and kidney, and faster in muscle, heart, gizzard and lung. Complete withdrawal of norfloxacin residues was as follows: gizzard (24 hours), followed by heart, muscle, lung and kidney and lastly by liver after 4
days.
The residue levels of norfloxacin in liver, muscles, kidney, heart, gizzard and lung of artificially infected E. coli chickens after intramuscular injection of norfloxacin (2.5 mg/kg b.wt. for 5 consecutive days) demonstrated that norfloxacin residues were more predominant in liver. The residue levels in chickens was nearly similar in pattern to that recorded in healthy ones. The maximum observed levels reached faster than that recorded in case of the healthy. The pattern of organ clearance from norfloxacin residues in artificially E. coli infected chickens is nearly similar to that observed in healthy ones where it disappears completely from muscles, heart, gizzard and lung after 3 days and from
kidney after 4 days followed by liver.
Correlation between norfloxacin residues in the studied organs of healthy chicken was highly positive between liver and lung, muscle and heart and moderately with kidney. A highly correlated relation was noticed between muscle and (lung, heart & gizzard) as w 11 as bet w en heart and (lung, & gizzard) and likewise, between gizzard and lung. The correlation between the residual levels is generally lower in artificially E. coli infected chickens than that observed in healthy chickens. Time needed to norfloxacin to reach its maximum levels in tissue is nearly similar in healthy and artificially E. coli infected chickens.
Effect on liver function:
Injection of norfloxacin into healthy chickens produced non-significant changes of serum direct, indirect as well as total bilirubin levels compared with control group allover the experimental period, on the other hand infection with E. coli evoked a significant elevatation (P < 0.001). Treatment of E. coli infected chickens with norfloxacin elicited a significant decrease (P < 0.001) of direct, indirect and total bilirubin levels compared with the control group (infected and non-treated) starting from the 7th day post-treatment through the end of the experiment (3 weeks).
Administration of norfloxacin to chickens infected with E. coli elicited a significant decrease in activities of serum AST, ALT and ALP while, in healthy chickens caused non-significant elevation in the activities of these enzymes along the entire period of the experiment compared with the control group. The serum cholinestease activity of healthy and infected chickens was non significantly affected as a result of treatment with norfloxacin b.wt. for 5 successive days throughout the experimental period (21 days).
Concerning, kidney function parameters (creatinine, uric acid and urea) in both healthy and infected chickens, injection with norfloxacin intramuscularly did not reveal any significant alteration between their level in serum of control and treated healthy chickens allover the experimental period. Whereas, the levels of these parameters were significantly elevated as a result of infection with E. coli These elevated parameters were reverted to nearly the control values (non infected non-treated) as a result of treatment with norfloxacin.
Therefore, it is believed that norfloxacin is a useful antibiotic in Egyptian farms against different types of microorganisms.