haemolytic activity and streptomycin susceptibility profile of bacterial isolates associated with nasal secretion

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HAEMOLYTIC ACTIVITY AND STREPTOMYCIN SUSCEPTIBILITY PROFILE OF BACTERIAL ISOLATES ASSOCIATED WITH NASAL SECRETION

CHAPTER ONE

 

1.0                                                INTRODUCTION

            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-haemolyticStreptococci (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).

Antimicrobial resistance is a natural biological phenomenon. It is a predictable outcome of antimicrobial use, the rapid which resistance emerges and its extent are proportional to the intensity of antimicrobial use (Lindsey, 2001). Resistance emerges in population with a high frequency of infection, due to either underlying patient status or interventions compromising host defenses, resulting in high rate or antimicrobial use. The introduction of every antimicrobial agent into clinical practices have been followed by the detection in the laboratory of strains of micro-organism which have resistant traits. Such resistance may either be a characteristic associated with the entire species or emerge in strains of normal susceptible species through mutation or genes transfer (Cheesbrough, 2006). Resistant genes encode various mechanisms, which allows micro-organisms to resist inhibitory effects of specific antimicrobials. These mechanisms offer resistance to other antimicrobials of the same class and sometimes to difference classes of antimicrobial (Coast et al., 1996). A nasal swab can be evaluated at the laboratory for some of the more common viruses and bacteria that cause upper respiratory tract infections. Nasal secretion can be benign due to wind or dust and irritation can be due to allergies, it can be indicative of an upper respiratory tract viral infection, or it can be the early stages of a more serious infection or it can be the early stages of a more serious infection.

1.1       AIMS AND OBJECTIVES

The aims and objectives of the study are:

  1. To determine the prevalence of bacterial pathogens that are commonly associated with nasal secretion.
  2. To determine the haemolytic activity of the bacteria associated with nasal secretions.

To investigate the susceptibility of the organisms  to streptomycin.

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