The current study of discovering new antimicrobial compounds in all
fields of microbial control has stimulated research regarding the
antimicrobial properties of plant compounds. The watery origano
extract was investigated for its antimicrobial activity both in vitro and
in vivo. The in vitro study was carried out to estimate the antibacterial
activity of watery oregano extract against E. coli, Pseudomonas
vulgarius, Enterobacter aerogenes, Salmonella species and
Staphylococcus aureus isolated from 60 fecal samples of diseased and
(liver, intestine, spleen and kidney) of 25 freshly dead broilers
collected during an outbreak in small private poultry farm in
Ismailia.The obtained results indicated that watery oregano extract
was effective against all isolated tested organisms. The in vivo study
was established to investigate its efficacy against experimentally
induced colibacillosis in broiler chicks. This study was carried on 120
apparently healthy un sexed one day-old broiler (Lohman) chicks. At
15th day, they were randomly allocated into main equal 6 groups (of
20 chicks each). The 1st group was non infected non treated, the 2nd
was non infected oregano extract treated, the 3rd was E. coli experimentally infected non treated, the 4th was E. coli experimentally
infected and oregano extract treated, the 5th was E. coli
experimentally infected ciprofloxacin treated and the 6th was E. coli
experimentally infected oregano extract and ciprofloxacin treated. All
treatments given orally in drinking water, started 48 hour pos
infection and continued for 5 consecutive days. At 2nd, 9th, and 16th
day post cessation of treatment, 5 birds per group were slaughtered
for blood, serum (for some haematological and biochemical studies)
and tissue samples (bacteriological reisolation). The obtained findings
displayed that, the mortalities were reduced from 25% in infected non
medicated group to 15% (G:4) and zero% in (G:5) and(G:6),
respectively. All infected treated groups showed a greater reduction in
clinical symptoms and postmortem lesions severity, especially in
groups (G:5) and (G:6). The haematological findings revealed an
increase in lymphocyte count in (G:2), (G:4) and (G:6). The
biochemical study displayed that treatment of infected groups watery
oregano extract, ciprofloxacin or both in combination induced an
improvement in both liver and kidney functions as compared to
infected unmedicated group. In conclusion our results confirm the
antimicrobial potential watery oregano extract both in vitro against
all isolated tested pathogenic microorganisms in this study and in vivo
against experimentally induced colibacillosis in broilers. Additionally,
our findings support the use of watery oregano extract in combination
with known antibacterial drugs to enhance the immunity and reduce
incidence of bacterial resistance. However, further research studies
are still needed to verify its antimicrobial effectiveness and to evaluate
its protection against pathogens as well as to investigate its
mechanism of action. Moreover, the bioassay-guided fractionation
procedure to characterize and isolate the antimicrobial constituents is
needed .