This study was carried out on hemolytic activity and streptomycin susceptibility profile of bacteria isolates associated with nasal secretion. To date, very little work has been done on the respiratory system flora of apparently healthy cattle. The objective of this study was to identify bacterial species found in the upper respiratory system and lungs of apparently healthy cattle; the isolates from nasal cavity were tested for susceptibility to selected antimicrobials. A total of 255 nasal swabs were collected from apparently healthy cattle in Maiduguri, Kaduna and Kano states, Nigeria, from which four hundred and four (404) bacterial isolates were identified, following the identification criteria given by Shears et al., (1993) and Quinn et al., (1994). They included: Bacillus 160/404 (39.60%), coagulase negative Staphylococcus 121/404(29.95%), Streptococcus species other than Streptococcus agalactiae 104/404 (25.74%), coagulase positive Staphylococcus 16/404 (3.96%) and Streptococcus agalactiae 3/404 (0.74%). Additionally, coagulase negative Staphylococcus (37.04%), coagulase positive Staphylococcus (37.04%), Streptococcus species (14.81%) and E. coli (11.11%), were also isolated from cattle lungs obtained from Athi river cattle slaughterhouse, some of which were showing pathological lesions. When the nasal isolates were tested for antimicrobial susceptibility, they were found to be most susceptible to Gentamycin (95.8%), followed by Tetracycline (90.5%), Kanamycin and Chloramphenicol (each at 85.3%), Sulphamethoxazole (84.2%), Co-Trimoxazole (82.1%), Ampicillin (78.9%) and finally Streptomycin (76.8%). Antimicrobial resistance was reported in
ascending order in Gentamycin (4.21%), followed by Tetracycline (9.47%), Kanamycin and Chloramphenicol (14.74%), Sulphamethoxazole (15.79%), Co-Trimoxazole (17.89%), Ampicillin (21.05%) and finally Streptomycin (23.16%). Multidrug resistance was reported in 30.5% of all isolates subjected to the test antimicrobials. Most of the resistant organisms showed resistance to a combination of two antimicrobials which was 20% of the total number resistant. This study indicated presence of similar bacteria in both nasal cavity and lungs, thus strongly suggesting the involvement of the otherwise harmless nasal commensals in pulmonary disease causation in cattle. These nasal bacteria may find their way to the lungs in cases when the animals are stressed, as a result of the harsh conditions that the animals live in and also in the way they are used for transport and are burdened by humans. The levels of antimicrobial resistance to the antimicrobials used, as demonstrated in this study, indicate that the antimicrobial resistant normal flora (bacteria) harbor resistance genes which are transferable to pathogenic bacteria in the animal, not to mention transfer of resistant bacteria to other animals and humans; compounding the antimicrobial resistance situation. This study identified Gentamycin, Tetracycline, Kanamycin and Chloramphenicol as the most effective antimicrobials that can currently be used for treating respiratory or other infections in cattle.
1.1 Background information
Infectious diseases are the world’s major threat to human health and account for almost 50,000 deaths everyday (Ahmad and Beg, 2001). The most important reason for the use of antimicrobial agents is to cure or prevent infectious diseases by using the best available agents. The study of antimicrobial susceptibility patterns of common pathogens in nasal secretions and the periodic review of such data is very essential in modern health care and the data provide a pre-emptive therapy either on the receipt of culture reports or a guide for overall course of treatment where therapy might be wholly empirical without laboratory diagnosis. This is fast becoming the norms in many developing countries as a result of dwindling resources (WHO, 2001). The benefits of the individual who deserves treatment must be weighed against the risk of emergence of resistant micro-organisms to the public (Kunin, 1988).
The choice of antimicrobial chemotherapy is initially dependent on clinical diagnosis. However, for many infections, establishing a clinical diagnosis implies determining possible microbiological causes which requires laboratory information from samples collected, preferably before antibiotic therapy is begun. Laboratory isolation and susceptibility testing of organisms make diagnosis to be established and also make drug selection more rational.
Microbial flora are those micro-organisms that make their home in some parts of the human body. These micro-organisms of which majority are bacteria comprise of the microbiota also termed normal flora (Michael et al., 1993). The microbial flora consists of the normal and transient flora. The microbial flora of man has physiological peculiarities that enhance their survival in their natural habitats on mucosal surface, and in competition with other bacteria. In the human body, the term normal flora implies that the micro-organisms are harmless, and in most parts they do not cause diseases and are even beneficial some are opportunities pathogens; that is, they may cause infections if tissue injury occurs at specific sites or if the resistance of the body to infection is decreased (Michael et al., 1993). Most are commensals; they benefit from the association with the host but the host is not affected. Others have a mutual association with the host; they benefits from the host in some ways while thriving in the host’s body. This is important because in recent years there has been a rising incidence of infection from these micro-organisms.
The normal flora present colonization of the body area by virulent strains of other micro-organisms and readily re-establishes when it is disturbed while the transient flora inhabits the mucous membrane briefly and are mainly itself from exogenous environment sources (Kunin, 1988). The nose is the most common reservoir for these micro-organisms. (Kunin, 1988).
Nasal secretion can vary in significance, from being innocuous to being indicative of a serious problem. Microbial flora can be responsible for endogenous or exogenous infections and the presence of a foreign body in the nose is a relatively uncommon occurrence(Nelson, 1994). Some of the species of Streptococci and Staphylococci are among the most important pathogens of man and children are the more susceptible to the infection caused by them (Nelson, 1994). Unlike foreign bodies in other parts of the body that often produce noticeable symptoms, foreign bodies in the nose can go unrecognized for significant periods of time. A low incidence of common microbial flora of bacteria, fungi, viral and protozoal origin has been observed and the recent study revealed a carrier rate of 14.1% for beta-haemolytic Streptococci (Nelson, 1994).
The bacteria flora of the nasal cavity has been studied extensively and exhaustively for the definition of the composition of the normal flora and for the identification of nasal carriers of certain bacterial species such as Streptococcus pyogenes or Staphylococcus aureus for the purpose of epidemiology. The major components of the normal flora of the nasals cavity are coagulase negative Staphylococci (which was reported to be present in widely varied percentage. Ranging from 12 to 81%), Staphylococcus aureus (6 to 34%) and many aerobic species, such as Streptococci of the viridans group, Meningococci, enteric bacteria and Moraxella species have been isolated occasionally, (Hannele et al., 1989). There are many different types of nasal secretion, it can be serous (clear, watery) , mucoid (yellow and mucous- like), purulent (green-yellow, thick, looks like pus) or sanguineous (bloody). Nasal secretion can be unilateral (only ever from one nostril) or bilateral (from both nostrils) which helps identify the source of the secretion. Secretion that is unilateral typically comes from the nasal passage, the sinus while bilateral secretion can arise from the pharynx, or the lower respiratory tract (trachea and lungs) secretion can also be constant or intermittent. Nasal secretion can be acute in onset within hours to a couple of days) or chronic (lasting more than 2-3 days). Nasal discharge may be the only clinical symptom or there may be other clinical symptoms as ocular discharge, enlarged lymph nodes (which is non-specific and present with many types of nasal discharge), fever, cough, abnormal noise when breathing or exercising, lethargy or weight loss. Sometimes, nasal secretion can have a foul odour, which can be specific to certain types of bacterial infections, tissues damage or sinus infections (Hannele et al., 1989).