PREVALENCE AND ANTIMICROBIAL SUSCEPTIBILITY OF GRAM NEGATIVE BACTERIA IN THE URINE OF CARITAS UNIVERSITY STUDENTS

CHAPTER ONE

INTRODUCTION

Gram negative bacteria are bacteria that do not retain their crystal violet dye in the gram staining protocol. They are differentiated by their cell wall structure. The following characteristics are displayed by gram negative bacteria as follows

Cytoplasmic membrane

Thin peptidoglycan layer(much thinner than gram positive)

Outer membrane containing lipopolysaccharide outside the peptidoglycan layer

Porin exists in the outer membrane, which acts like pores

There is a space between the layer of peptidoglycan and the secondary cell membrane, called the periplasmic space

If present, flagella have four (4) supporting rings instead of two

No techoic acid or lipopolysaccharide

Some examples of gram negative bacteria include; Escherichia coli, Salmonella species, Pseudomonas species, Klebsiella species, Proteus species, Helicobacter species, Mosoxella species, Cyanobacteria species, Spirochetes species.

They also constitute a serious problem in urinary tract infections in many parts of the world. Appropriate antimicrobial treatments are often critical to decreasing morbidity and mortality among hospitalized patients having the infections caused by the pathogens. Gram negative bacteria are non-spore forming bacilli that grow rapidly on ordinary laboratory media under both aerobic and anaerobic conditions. It has been estimated that symptomatic urinary tract infects (UTI) occurs in as many as 7million visits to emergency units and 100,000 hospitalised annually. UTI has been the most common hospital acquired infections, accounting for as many as 35% of nosocomial infection. It is the second most common cause of bacteraemia in hospitalised patients (Nacem, 2000). UTI is known to occur in all populations but has a particular impact on females of all ages and males at two extremes of life, immuno-compromised patients and anyone with function or structural abnormalities of the urinary and excretory system.

UTI is known to be the microbial invasion of any of the tissues of the urinary tract reaching from the renal cortex to the urethrameatus (Nicolle, 2000). It is also known to be the presence in two consecutive urine samples of greater than 100rods (105 ) organisms per ml of a single bacterial strain in the urinary tract. UTI can be categorized in ascending or descending. Infections which are confined to the urethral or the bladder are ascending and referred to as uretitis or cystitis respectively. On the other hand, the pathogens spread from one or other infected body site to the kidney down along the ureter to the bladder. Such descending UTI cause severe kidney infection, a condition called pyelonephritis (Parsons, 1958). This is potentially more serious; infections to the urethra are called urethritis and to the prostrate gland are called prostitis. This classification is the presence or absence of symptoms, reoccurrence or absence or presence of complicating factors which are host factors facilitating establishment and maintenance of bacteraemia or worsening the prognosis of UTI`s engaging the kidney.

Majority of pathogens are gram negative species with predominance of members of Enterobacteriace (Neu, 1992). Escherichia coli accounts for majority of urinary tract infections in young women but other gram negative 16

rods of different genera such as proteus species and pseudomonas aeruginosa an aerobic gram negative rod is also troublesome. As a urinary tract pathogens because of its resistance to antimicrobial medicine make it difficult to treat successfully (Nester et al. 1998).

Antibiotics are used for the control of bacterial infections in human. Generally, gram negative bacteria are sensitive to many antimicrobial agents but strains from different patients and carriers differ in the pattern and degrees of sensitivity to different drugs. Increasing antimicrobials resistance in bacterial pathogen is a worldwide concern. The prevalence of antimicrobial resistance among urinary tract infectious agents is also increasing (Mathai et al. 2001 : Karaloswsky et al. 2001) and its treatment has become more complicated due to increasing resistance and empirical therapy leading to treatment failures of most associated with gram negative bacteria (Blondeau et al. 1999). The present study investigated the pattern of gram negative uropathogens and their antimicrobial resistance pattern among the clinical isolates to the commercially available antibiotics that are often prescribed in urinary tract infectious cases

1.1 Aims and objectives

To find out the prevalence of gram negative organisms in the urinary tract among caritas university students.

To investigate their antibiotic sensitivity pattern to enable formulation of drugs for urinary tract infection in our community.

To determine the age and sex prevalence.

To determine the prevalence of bacterial strains and their antimicrobial susceptibility in urine.

To find the pathogenic bacteria commonly responsible with UTI and susceptibility patterns this will help the clinicians to choose the right empirical treatment.

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MicroBiology

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