Streptococcus pneumoniae

ACKNOWLEDGEMENT
aCKNOWLEDGEMENT

Table of Contents

Contents Page

 Introduction 3-7
 Methodology 7-8
 Results and Discussion 8-9
 Conclusion 9
 Acknowledgement 10
 References 10































INTRODUCTION
Pasteur discovered Streptococcus pneumoniae in 1880 and before long this organism caused pneumonia.Coope described lobar pneumonia as that “which consist of a series of changes by which the spongy pulmonary tissue is rapidly converted into a solid mass” The symptoms of pneumonia were described by Hippocrates. Pneumonia is an infection of the small air sacs of the lungs (alveoli) and the tissues around them. Pneumonia is one of the most common causes of death worldwide. Pneumonia is the sixth most common cause of death overall, and the most common fatal infection acquired in hospitals. Pneumonia may develop in people living in the community (community-acquired pneumonia), in the hospital (hospital-acquired pneumonia), or in some other institutional setting, such as a nursing home (nursing home–acquired pneumonia). In other cases, pneumonia is caused when bacteria or viruses that are normally present in the mouth, throat, or nose inadvertently enter the lung. During sleep, it is quite common for people to aspirate secretions from the mouth, throat, or nose. If a person is in a weakened condition from another illness, a severe pneumonia can develop. People with recent viral infections, lung disease, heart disease, and swallowing problems, as well as alcoholics, drug users, and those who have suffered a stroke or seizure are at higher risk for developing pneumonia than the general population.
The main types of pneumonia are:
• Bacterial pneumonia - caused by various bacteria. The Streptococcus pneumoniae is the most common bacterium that causes bacterial pneumonia.
Many other bacteria may cause bacterial pneumonia including:
Group B streptococcus (most common in newborns), Staphylococcus aureus, Group A streptococcus (most common in children over age 5)
• Viral pneumonia - caused by various viruses, including the following: respiratory syncytial virus, or RSV (most commonly seen in children under age 5),parainfluenza virus, influenza virus, adenovirus
Viral pneumonias may make a child susceptible to bacterial pneumonia.
• Mycoplasmal pneumonia - presents somewhat different symptoms and physical signs than other types of pneumonia. It is caused by mycoplasmas, the smallest free-living agents of human disease, which have the characteristics of both bacteria and viruses, but which are not classified as either. They generally cause a mild, widespread pneumonia that affects all age groups. [www.schniederchildrenhospital.org/peds.html]
Here we studied only bacterial pneumoniae i.e. Streptococcus pneumoniae
Streptococcus pneumoniae, or pneumococcus, is a Gram-positive, lancet shaped cocci.Usually they are seen as pairs of cocci (diplococci) but they may also occur singly and in short chains. They do not form spores and they are nonmotile.When cultured on blood agar they are hemolytic. Despite the name, the organism causes many types of infection other than pneumonia, including acute sinusitis, otitis media, meningitis, bacteremia, osteomyelitis, septic arthritis, endocarditis, peritonitis, pericarditis, cellulitis, and brain abscess. S. pneumoniae is the most common cause of bacterial meningitis in adults and children, and is one of the top two isolates found in ear infection, otitis media.
S.Pneumoniae is particularly labile organism,sensitive to heat,cold and drying and transmission requires close person to person contact. Like other streptococci they lack catalase and ferment glucose to lactic acid. The cell wall composition is characteristic both in terms of their peptidoglycan .

Gram stain of S.pneumonia [Source: C.D.C]
Pneumococci spontaneously cause disease in humans, monkeys, rabbits, horses, mice and guinea pigs .It is normally found in nasopharynx of healthy person. It attaches to nasopharyngeal cells through interaction of bacterial surface adhesions. Upon reaching the lower respiratory tract, pneumococci bypass the ciliated upper respiratory epithelial cells unless there is damage to the epithelium. Instead, they progress to the alveolus and associate with specific alveolar cells. Bacteria also produce the toxin pneumolysin that destroys host cells. The air sacs (alveoli) fill with fluid and pus, making it difficult for the person affected to breathe.

Alveoli filled with fluid [Source: www.uptodate.com]

When the air sacs in the lungs fill it impairs their main function, which is to get oxygen from the air into blood stream. Lungs become less elastic and cannot take oxygen into the blood or remove carbon dioxide from the blood as efficiently as usual. S.Pneumonia affects the lungs in two ways. If the inflammation affects a section (lobe) of a lung it is called lobar pneumonia and if patches throughout both lungs are affected it is known as bronchial pneumonia. Pneumonia can be very serious, because it directly interferes with your body’s ability to exchange carbon dioxide and oxygen.

Diagram showing exchange of carbondioxide and oxygen in alveoli [www.uptodate.com]

[Source: kms.kaparama.ksbe.edu]
The usual symptoms for pneumonia are:
• High Temperature i.e.105F
• Severe Shaking and chills
• Cough that produces rust colored or greenish mucus
• Severe chest pain and tightness in the chest
• Shortness of breath
• Loss of appetite
• Tiredness and Fatigue
• Rapid pulse and rapid breathing occur
• Bluish colored to lips and nail beads
• Confused mental state
• Sweating and aching
• Expectoration of blood
• Vomiting and diarrhea
METHODOLOGY

A doctor checks for pneumonia by listening to the chest with a stethoscope. It usually produces distinctive sounds. These abnormal sounds are caused by narrowing of airways or filling of the normally air-filled parts of the lungs with inflammatory cells and fluid, a process called consolidation. In people who are very sick then doctors often culture specimens of sputum, blood, and urine in an attempt to identify the organism causing pneumonia. It is particularly important to identify the causative organism when people are severely ill, do not have a normal immune system, or are not responding well to treatment. However, despite these tests, the precise organism cannot be identified conclusively in most people who have pneumonia.When cultured on blood agar plates with added optochin antibiotic disk, they show alpha-hemolytic colonies and a clear zone of inhibition around the disk meaning they're sensitive to the antibiotic. (John G.Bartlett)

Diagram showing α-hemolytic colonies on bood agar [Source: http-web-indstate-edu-thcme-micro-alfahem-jpg.htm.]
Pneumococci are bile soluble. Just like other streptococci, they are catalase negative. A recently developed urinary antigen test may provide a rapid diagnosis of pneumococcal pneumonia in adults

Bile positive test shown by Streptococcus pneumoniae
[Source: randstarteam.blogspot.com]

RESULTS AND DISCUSSIONS
People with pneumonia who are short of breath or have low levels of oxygen in their blood are given supplemental oxygen. Although rest is an important part of treatment. Usually antibiotics are started whenever bacterial pneumonia is suspected, even before the organism is identified. Often, people who have pneumonia but are not very sick can take oral antibiotics and remain at home. Older people, infants, and those who are short of breath, are very sick, or have preexisting heart or lung disease are usually hospitalized and given intravenous antibiotics to start. People may also need supplemental oxygen, intravenous fluids, and, if they are very sick, mechanical respiratory support. Antibiotics are not helpful for viral pneumonias. Pneumonia was susceptible to penicillin. Penicillin G /amoxicillin remain the drug of choice for strains that are fully sensitive. Varying proportion of strains may also be resistant to cephalosporins, macrolides (such as erythromycin), tetracycline, clindamycin and the quinolones.Cefotaxime and ceftriaxone are the first-line alternatives in cases with higher levels of resistance.(Prescott et al)

The most effective way to prevent pneumonia is to stop smoking. Certain pneumonias can be prevented with immunizations. (CDC)
Pneumococcal pneumonia vaccine: Pneumococcal pneumonia, which is caused by Streptococcus pneumoniae, can sometimes be prevented with the pneumococcal pneumonia vaccine. The organism that causes pneumococcal pneumonia can also cause many other infections (such as infections of the blood and meningitis). The pneumococcal pneumonia vaccine also protects people from many of these serious pneumococcal infections. Vaccination is recommended for people at high risk of pneumococcal pneumonia—such as all those older than 65 and younger adults who have lung or heart disease, a weakened immune system, or diabetes or who have had their spleen removed. The protection from vaccination may last a lifetime, although it is recommended that people at highest risk be revaccinated after 5 years. Pregnant women should not receive this vaccine.
Pneumococcal conjugate vaccine: Pneumococcal conjugate vaccine also protects against pneumococcal infections, including pneumonia. This vaccine is given to children younger than 2 years old.
There is currently research into producing vaccines than can be given into the nose rather than by injection. It is believed that this improves vaccine efficiency and also avoids the need for injection. The development of serotype-specific anticapsular monoclonal antibodies has also been an area of vaccine research in recent years. These antibodies have been shown to prolong survival in a mouse model of pneumococcal infection characterized by a reduction in bacterial loads and a suppression of the host inflammatory response.
Conclusion
The result of the present study shows that the tendency toward increasing penicillin resistance in pneumococci in many other parts of world (Spain) may have ended over the last few years. In contrast, erythromycin resistance has been growing continuously. Researchers found decrease in the susceptibility rates for ciprofloxacin over a short time period. Therefore general condition of patients such as immunity is more important which is not there in case of antibiotics but in case of vaccine it is there.
Acknowledgement

From the bottom of my heart, I would like to thank my teacher Dr. Pooja Tandon as without their expertise advice and help, this project would not have been completed. She has not only helped me as a teacher but her boosting and enthusiastic and friendly nature constantly inspired me throughout the endeavor.

While writing this report, I have kept in mind the entire requirements needed. Although every care has been taken to check the entire mistake & misprint. Yet it is difficult to claim perfection.

References
1. CDC. Prevention of pneumococcal disease: Recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR 1997; 46 (no.RR-08).
2. Streptococcus pneumoniae © 2008 Kenneth Todar University of Wisconsin-Madison Department of Bacteriology.
3. John G.Bartlett, MD copyright ©1995-2008 Merck & Co; inc
4. www.schniederchildrenhospital.org/peds.html
5. Prescott, Harley and Klein (2002) Microbiology, 5th ed, McGraw Hill.ISBN 0-07-282905-2.