Sudan sheep wealth contribution in the national income is limited by superficial lymph node abscesses (LNA), which according to the Annual Reports of Port Sudan Veterinary Quarantine (1996-2005) resulted in rejection of 2.75% of sheep inspected and almost 4% of sheep exported to the Kingdom of Saudi Arabia.
This study meant to investigate export sheep for LNA and bacterial causes in correlation with site of affected lymph nodes, sheep breeds, internal quarantines, quarantine period, weight and age-group; to facilitate establishment of effective control measures.
The mean number of sheep rejected from exportation was (1.44±0.95), of which LNA was (0.60±o.41) and that constituted (48.99±26.82) of total rejections. Lymph nodes affected and other cases, in order, were: parotid, submandibular, prescapular, involvement of two types of lymph nodes, precrural, other superficial abscesses and then cases of involvement of multiple types of lymph nodes. There was, relatively, proportional increase in rates of LNA with increased sheep weight, age and quarantine period. The Zagawi and Kubbashi sheep exceeded the Hamari in rate of affection, but the Butana and Garag breeds, though least affected, showed significant differences in Parotid cases; the Hamari and Kubbashi breeds shared showing cases of other superficial abscess alone, while the Kubbashi exhibited the highest rates of prescapular cases.
Cases of involvement of multiple types of lymph nodes, which reflected mainly in vivo dissemination of pathogens, were found only in the Hamari, Zagawi and Garag breeds. LNA of sheep came from Rahad, Khowi and Kadaro quarantines (western breeds) were significantly high than those of Shoak quarantine (Butana breed), but, sheep of the Khowi were top in both, multiple enlarged lymph nodes and other superficial abscesses. Right Parotid and other superficial abscesses cases were significantly different in sheep quarantined less than 2 weeks, while sheep exceeded two weeks exhibited high rate of prescapular lymph cases. Sheep less than 35 Kg and more than 25 Kg were highly affected by parotid and submandibular lymph cases, while affection with prescapular LNA increased with increased weight, notably, decreased rate of submandibular and other superficial abscesses was shown by sheep weighing more than 45 Kg. Parotid cases were equally shown by all age groups, but sheep less than one year old were significantly higher in submandibular LNA, while prescapular cases scored the peak in older sheep. Correlation analysis linked, generally, sheep LNA with sheep quarantine period and weight; the quarantine period, specifically, correlated with submandibular, right prescapular and left parotid LNA; the weight with parotid LNA; while cases of involvement of two types of lymph nodes with the submandibular, parotid and prescapular LNA and other superficial abscesses.
The right and left precrural LNA correlated with each other and with involvement of multiple types of lymph nodes; finally the other superficial abscesses correlated only with the parotid LNA.
Out of 143 pus samples, 129 bacterial isolates were obtained. According to their microscopic, cultural and biochemical characteristics, these isolates were identified as: S. aureus subsp. anaerobius (12%); S. aureus other than subsp. anaerobius (8%); other staphylococci (27%); C. pseudotuberculosis (5%); Arcanobacterium pyogenes (3%), Clostridium species (1%), Micrococci and Peptococci (8%), Bacilli (9%), Enterobacteria (10%), Pseudomonas species (3%) and other Gram-negative bacteria 4%.
Fourteen samples were negative for any type of growth.
The staphylococci predilection sites were the parotid and prescapular lymph nodes, while C. pseudotuberculosis and A. pyogenes were mainly isolated from prescapular lymph nodes. No significant differences were found for pathogens in different sheep breeds, except the Coagulase-negative staphylococci which were significantly higher in number in Garag breed. Most types of bacterial isolates were found in the Hammari breed, but C. Pseudotuberculosis and A. pyogenes were not isolated from the Kubbashi. S. aureus subsp. anaerobius were found in all breeds, but S. aureus was not isolated from the Zagawi or Garag breeds.
Antibiotic sensitivity test was performed for all isolates, 12 type of antibiotics against Gram-positive and Gram-negative bacteria (four of them shared).
The Gram-positive isolates, mainly staphylococci, were collectively over 60% sensitive to antibiotics, specifically to Gentamycin and Tetracycline; almost 50% were resistant to Ampicillin, Streptomycin, Cloxacillin, Chloramphenicol and Erythromycin; while 90% were resistant to Penicillin, which reflected a serious build up of antibiotic resistance.
Exceptionally, Actinomyces pyogenes were 100% sensitive to Tetracycline and 75% to Cloxacillin. The Gram-negative isolates were over 65% resistant to most antibiotics, mainly Ampicillin, Cotrimizol, Tetracycline, Nalidixic acid and Colistin; 100% were resistant to Nitrofurantoin; while 60% of isolates were sensitive to Gentamycin and 50% to Streptomycin.