Streptococci, Flesh Eating Bacteria

Medical and Health Science Project and Seminar Material

Streptococci, Flesh Eating Bacteria


Abstract


Group A beta-haemolytic streptococcal infections have a worldwide distribution among children and it poses an important health problem globally. The study therefore, was aimed at evaluating streptococci flesh eating bacteria. Erythromycin was found to be the most effective antibiotics against Streptococcus pyogenes from this study. A prevalence of 14.7% was recorded for ASO in sera samples.

The level of ASO in patients that tested positive for the presence of ASO ranged from 200IU/ml to 16,000IU/ml. GS21 and GS7 showed the highest concentration of 16,000IU/ml respectively with a mean of 1772IU/ml. Two individuals were recorded to be both positive for Streptococcus pyogenes from throat swab samples as well as positive for Anti- streptolysin O antibody (ASO) from sera samples.

The findings showed that children and parents who practiced good hygiene, cultured less Streptococcus pyogenes as well as those who had good ventilation in school, at home and those who were previously exposed to the infection and completed antibiotics treatment. The findings showed the effectiveness and sensitivity of the use of immunological assay (ASO) for diagnosis of Streptococcus pyogenes infection alongside the use of cultural method.


Table Of Content


Preliminary Page(s)

  • Title page
  • Certification page
  • Dedication
  • Acknowledgement
  • Abstract
  • Table of content

Chapter One

1.0 Introduction

  • 1.1 Background of the Study
  • 1.2 Statement Problem
  • 1.3 Research Objective

Chapter Two

2.0 Review Of Related Literature

  • 2.1 Conceptual Review
  • 2.2 Empirical Review

Chapter Three

3.0 Descriptive And Empirical Results


Chapter Four

4.0 Conclusion And Recommendation

  • References

Chapter One


1.0 Introduction

1.1 Background of the Study

Streptococcus pyogenes is a spherical, Gram-positive, non-motile, non-sporing bacterium that occurs as long chains of cocci and occasionally in pairs. It is less than 2µm in length and forms colonies greater than 0.5mm in size (Murray et al., 2007). It is catalase-negative and has been classified in group A, using Lancefield serotyping because it displays antigen A on its cell wall. Therefore, this bacterium is commonly called the group A (beta-haemolytic) Streptococcus (GABHS or GAS) (Todar, 2002). This pathogen is classified as group A Streptococcus, typically having a capsule composed of hyaluronic acid and are beta-haemolytic which is true for Streptococcus pyogenes (Todar, 2005).

Beta-haemolytic streptococci produce a toxin that forms a clear zone of haemolysis on blood agar, demonstrating its ability to destroy red blood cells. This haemolysis is attributed to toxins formed by group A streptococci called “Streptolysins” which can destroy not only the red blood cells but also the white blood cells responsible for destroying pathogens (Tortora et al., 2007). This bacterium is the causative agent for bacterial pharyngitis, tonsillitis and a wide range of both invasive and non-invasive infections. The name is derived from the Greek word “streptos”, meaning „twisted chain‟ due to the fact that the bacterium resembles a string of small pearls when viewed under the microscope.

Infection of group A Streptococcus may spread through direct contact with mucus or sores on the skin (CDC, 2012). A sore throat infection is often a symptom of a bacterial or viral infection.

This bacterium causes over 50,000 deaths per year (Cohen-Paradosu and Kasper 2007). Despite the emergence of antibiotics as treatment for group A beta-haemolytic Streptococcus infection, this bacterium has become an increasing problem, particularly in the continent of Africa (Carapetis et al., 2005). Usually persons with suppressed or compromised immune system may be susceptible to certain diseases caused by group A Streptococcus than other persons who are immuno-competent. Group A Streptococcus may be present on the skin or in the throat of people and show no symptoms, known as carriers. Non-invasive infections occur when the bacteria colonise the throat area, where they colonise epithelial cells (CDC, 2012).

The two most important infections of group A streptococci are invasive and non-invasive infections. Non-invasive infection includes: pharyngitis where it causes 15-30% of childhood cases and 10% of adult cases including scarlet fever (Cohen-Paradosu and Kasper 2007). The invasive infections caused by group A beta-haemolytic Streptococcus tend to be more severe. This occurs when the bacterium is able to infect areas where bacteria are not usually found, such as blood and organs, as a result of haematogenous spread of the organism.

Group A streptococci may lead to further complications and health conditions such as: rheumatic fever, streptococcal toxic shock syndrome (STSS), necrotizing fasciitis (NF), Post-streptococcal glomerulonephritis (Cohen-Paradosu and Kasper 2007). All severe group A streptococci infections may lead to shock, multi-system organ failures and death. Early recognition and treatment is critical (Dwyer, 2012).

There are currently 74 species under the genus Streptococcus while Streptococcus pyogenes is one of the most virulent species causing human infections (Euzeby, 2012). Streptococcus pyogenes is one of the most common pathogens found worldwide and also the most pathogenic species in the genus Streptococcus. This bacterium can rapidly colonise and multiply within a host, causing acute infections such as “Strep throat” and impetigo to the severe necrotizing fasciitis “flesh eating” and Streptococcal toxic shock syndrome (Todar, 2002).

The pathogenesis of Streptococcus pyogenes infection usually begins in the throat and on the surface of the skin. From there, the bacterium begins to spread into deeper areas of the skin which can potentially lead to life-threatening diseases (Facklam, 2002). This bacterium can be found as a commensal in the upper respiratory tract, particularly in children (Cheesbrough, 2010). The main site of colonization is the oro-pharyngeal mucosa but other locations such as gastrointestinal tract and lower female genital tract can also be colonized. Person-to-person transmission involves respiratory droplets and direct contact.

Acute respiratory infections cause four and a half million deaths among children per annum, especially those in the developing countries (Berman, 1991). Acute respiratory tract infection remains an important cause of childhood morbidity and mortality in developing countries though this infection is potentially treatable and preventable (Gbadegesin et al., 1997).

Transmission of streptococcal infection is through the respiratory tract by inhalation of droplets, hand contact with nasal discharge and direct contact with lesions. In the last century, infections by Streptococcus pyogenes claimed many lives especially, since the organism was the most important cause of puerperal fever (Sepsis after child birth) (Todar, 2005).

The type of haemolytic reaction displayed on blood agar has long been used to classify the streptococci. Beta-haemolysis is associated with „complete lysis‟ of red cells surrounding the colony, while alpha-haemolysis represents “partial” or “green” haemolysis associated with reduction of blood haemoglobin. Non-haemolytic colonies have been termed gamma-haemolytic (Todar, 2005).


1.2 Statement Problem

There are at least 517,000 deaths reported globally each year (Carapetis et al., 2005). These deaths have been attributed to severe Streptococcus pyogenes infection and its prevalence increasing to 30-80%, with at least 18.1 million cases each year and 1.78 million new cases each year. Rheumatic fever alone causes 233,000 deaths (Carapetis et al., 2005). There are about 1,800 invasive Streptococcus pyogenes related deaths in the USA yearly with necrotizing fever killing 30% of patients and Streptococcal toxic shock syndrome with a mortality rate of 30%- 70% (Stevens, 1995; Murray et al., 2007; Torralba and Quismorio, 2009).

It was reported that 15-20% of school aged children has Streptococcus pyogenes in its carrier form in their throat and are more at risk of having the disease (Vincent et al., 2004; Bessen, 2009). If untreated, patients with streptococcal pharyngitis are infective during the acute phase of illness usually 7-10 days (Vincent et al., 2004). As of 2007, there were at least 18.1 million cases of invasive infections which are predominant in older population (Murray et al., 2007).

Streptococcus pyogenes can remain in the body of its carrier (humans) without causing illness in the host, for weeks or months and remains transmissible in this state (Bessen, 2009).


1.3 Research Objective

The objective of this study was to evaluate streptococci flesh eating bacteria.


Chapter Four


4.0 Conclusion And Recommendation

4.1 Conclusion

Acute respiratory tract infection remains an important cause of childhood morbidity and mortality in developing countries despite the fact that it is potentially treatable and preventable (Gbadegesin et al., 1997).
Various kinds of micro-organisms that infect the respiratory tract are transmitted through nasal and throat secretions of infected people, which are expelled as aerosols when they cough or sneeze (Constantainescu et al., 2002). The organisms responsible for upper respiratory tract infections ranges from bacteria, fungi, viruses and other micro-organisms that are pathogenic and are present in dust and air. It is therefore, important to diagnose if a respiratory tract infection is a bacteria source or not, so as to control the indiscriminate use of antibiotics.

The relationship between Streptococcus pyogenes infection and sex, shows that the prevalence of 8.9% in males was higher than that recorded in females (4.2%). This report shows that male children were found to be at higher risk of acquiring the infection than the females. This could probably be because the males are often involved in outdoor activities than the females; they have higher chances of interacting more with other children, exchange more playing materials.

Some risk factors were found to be predisposing factors to Streptococcus pyogenes infection in this study, though they were not statistically significant. Such risk factors included: poor ventilation in school, poor ventilation at home, poor level of hygiene of children, poor level of hygiene of nursing mothers, previous exposure to infection and incomplete drug administration.

In this study, the prevalence of Streptococcus pyogenes infection from throat swabs of children aged 0-5 years was 6.7% and Anti-streptolysin O antibody had prevalence of 14.7%. ASO was found to be more sensitive than culture, probably because as with many infections, pathogen recovery may be impeded by culture due to empirically initiated antibiotics administration.

In this study, two (2) patients were found to be positive both to Streptococcus pyogenes infection in the throat swab (culture) and ASO antibody in the sera.
Erythromycin was found to be the most effective drug for treatment of Streptococcus pyogenes infection in this study.

Anti-streptolysin O remains useful, in the diagnosis of streptococcal infections and their complications, follow- up as well as in evaluating the effectiveness of treatment. ASO is a much easier method than cultural method and could provide baseline information use for diagnosis.


4.2 Recommendation

  1. Proper and adequate ventilation should be encouraged in schools, day-cares and houses.
  2. Early and accurate diagnosis of streptococcal infection is important in order to avoid dissemination of the bacteria.
  3. Effective hand hygiene should be encouraged in our localities.
  4. Strict isolation procedures should be employed in patients who are admitted to hospitals with Group A streptococcal infection.
  5. Health care givers should educate and encourage patients on the importance of drug regimen compliance.
  6. Government should engage in enlightenment campaign programs to enlighten localities on the clinical manifestations, mode of transmission, complications and the importance to seek immediate medical attention if contacts develop symptoms related to Streptococcus pyogenes infection.
  7. Culture and ASO assay should be deployed routinely in laboratories which help in effective diagnosis and in the prescription of appropriate antibiotics.

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