CHAPTER ONE
INTRODUCTION
1.1 Background to the Study
Cattle are the most common and largest domesticated animal in the world (Bollongino,2012). They are reared for meat, milk and other dairy products. According to an estimate from 2011, there are about 1.4 billion cattle in the world. In 2009, cattle became one of the first livestock animals to have a fully mapped genome(Brown, 2009). They are herbivores because they feed on grasses, legumes and roughage. They are also known as ruminants because they have one stomach with four compartments. In Nigeria (West Africa), commercial beef cattle production is common especially in the Northern part of the country (Bollongino, 2012).
Pseudomonas aeruginosa (P. aeruginosa) is a bacterium capable of causing serious infections in cattle e.g. mastitis. It is found in the milk of cattle because it requires few nutrients to grow and multiply. Water supplies, contaminated drugs and infusion equipment are the major sources of this organism. It has also been isolated from waste feed, soil, manure and animal skin. Cows that are immunologically compromised due to other infectious diseases or are nutritionally deficient are also more susceptible to P. aeruginosa infections. The bacterium is resistant to antibiotics (John & Roger, 2011). In 2005, Haydar was able to isolate some bacteria causing pneumonia from the nasal cavity of healthy cattle especially in animals suffering from defects in their immune status or stressed (Haydar, 2005). About 2.43% of the isolates were Pseudomonas species. This showed that Pseudomonas aeruginosa can be an infectious agent in cattle and can be transmitted as zoonotic infection (Haydar, 2005).
Pseudomonas aeruginosa is a Gram-negative, rod-shaped, monoflagellated bacterium ranging from about 1-5 µm long and 0.5-1.0 µm wide (Lederberg, 2000). They are ubiquitous microorganism that can be isolated from soil, water, humans, animals, plants, sewage, and hospitals (Lederberg, 2000). Itis an opportunistic human pathogen which often colonizes immunocompromised patients such as those with cystic fibrosis, cancer or AIDS (Botzenhardt et al., 1993). Itis the second leading cause of Gram-negative nosocomial infections (Carmeli et al., 1999) carrying a 40-60% mortality rate (Fick, 1993). It has a natural resistance mechanism to many antibiotics because of a resistance transfer plasmid, extra genetic material carried in the cells with genes that code for proteins that destroy antibiotic substances (Madigan & Martinko 2006).