PNEUMONIA

What is pneumonia?

Pneumonia is an infection of one or both lungs which is usually caused by bacteria, viruses, or fungi. Prior to the discovery of antibiotics, one-third of all people who developed pneumonia subsequently died from the infection. Currently, over 3 million people develop pneumonia each year in the United States. Over a half a million of these people are admitted to a hospital for treatment. Although most of these people recover, approximately 5% will die from pneumonia. Pneumonia is the sixth leading cause of death in the United States.

What are pneumonia symptoms and signs?

Most people who develop pneumonia initially have symptoms of a cold (upper respiratory infection, for example, sneezing,sore throat, cough), which are then followed by a high fever ,shaking chills, and a cough with sputum production. The sputum is usually discolored and sometimes bloody. Depending on the location of the infection, certain symptoms are more likely to develop. When the infection settles in the air passages, cough and sputum tend to predominate the symptoms. In some, the spongy tissue of the lungs that contain the air sacs is more involved. In this case, oxygenation of the blood can be impaired, along with stiffening of the lung, which results in shortness of breath. At times, the individual's skin color may change and become dusky or purplish (a condition known as "cyanosis") due to their blood being poorly oxygenated.

The only pain fibers in the lung are on the surface of the lung, in the area known as the pleura. Chest pain may develop if the outer aspects of the lung close to the pleura are involved in the infection. This pain is usually sharp and worsens when taking a deep breath and is known as pleuritic pain or pleurisy. In other cases of pneumonia, depending on the causative organism, there can be a slow onset of symptoms. A worsening cough, headaches, and muscle aches may be the only symptoms.

Children and babies who develop pneumonia often do not have any specific signs of a chest infection but develop a fever, appear quite ill, and can become lethargic. Elderly people may also have few symptoms with pneumonia.

How is pneumonia diagnosed?

Your doctor will ask you about your symptoms and do a physical exam. He or she may order a chest X-ray and a blood test. This is usually enough for your doctor to know if you have pneumonia. You may need more tests if you have bad symptoms, are an older adult, or have other health problems. In general, the sicker you are, the more tests you will have.

Pneumonia may be suspected when the doctor examines the patient and hears coarse breathing or crackling sounds when listening to a portion of the chest with a stethoscope. There may be wheezing or the sounds of breathing may be faint in a particular area of the chest. A chest X-ray is usually ordered to confirm the diagnosis of pneumonia. The lungs have several segments referred to as lobes, usually two on the left and three on the right. When the pneumonia affects one of these lobes, it is often referred to as lobar pneumonia. Some pneumonias have a more patchy distribution that does not involve specific lobes. In the past, when both lungs were involved in the infection, the term "double pneumonia" was used. This term is rarely used today.

Sputum samples can be collected and examined under the microscope. Pneumonia caused by bacteria or fungi can be detected by this examination. A sample of the sputum can be grown in special incubators, and the offending organism can be subsequently identified. It is important to understand that the sputum specimen must contain little saliva from the mouth and be delivered to the laboratory fairly quickly. Otherwise, overgrowth of noninfecting bacteria from the mouth may predominate. As we have used antibiotics in a broader uncontrolled fashion, more organisms are becoming resistant to the commonly used antibiotics. These types of cultures can help in directing more appropriate therapy.

A blood test that measures white blood cell count (WBC) may be performed. An individual's white blood cell count can often give a hint as to the severity of the pneumonia and whether it is caused by bacteria or a virus. An increased number of neutrophils, one type of WBC, is seen in most bacterial infections, whereas an increase in lymphocytes, another type of WBC, is seen in viral infections, fungal infections, and some bacterial infections (like tuberculosis).

Bronchoscopy is a procedure in which a thin, flexible, lighted viewing tube is inserted into the nose or mouth after a local anesthetic is administered. Using this device, the doctor can directly examine the breathing passages (trachea and bronchi). Simultaneously, samples of sputum or tissue from the infected part of the lung can be obtained.

Sometimes, fluid collects in the pleural space around the lung as a result of the inflammation from pneumonia. This fluid is called a pleural effusion. If a significant amount of fluid develops, it can be removed. After numbing the skin with local anesthetic a needle is inserted into the chest cavity and fluid can be withdrawn and examined under the microscope. This procedure is called a thoracentesis. Often ultrasound is used to prevent complications from this procedure. In some cases, this fluid can become severely inflamed (parapneumonic effusion) or infected (empyema) and may need to be removed by more aggressive surgical procedures. Today, most often, this involves surgery through a tube or thoracoscope. This is referred to as video-assisted thoracoscopic surgery or VATS.

What are some of the organisms that cause pneumonia? What is the treatment for pneumonia? Can pneumonia be prevented?

The most common cause of a bacterial pneumonia is Streptococcus pneumoniae. In this form of pneumonia, there is usually an abrupt onset of the illness with shakingchills, fever, and production of a rust-colored sputum. The infection spreads into the blood in 20%-30% of cases (known assepsis), and if this occurs, 20%-30% of these patients die.

Two vaccines are available to prevent pneumococcal disease: the pneumococcal conjugate vaccine (PCV13) and the pneumococcal polysaccharide vaccine (PPV23; Pneumovax). The pneumococcal conjugate vaccine is part of the routine infant immunization schedule in the U.S. and is recommended for all children < 2 years of age and children 2-4 years of age who have certain medical conditions. The pneumococcal polysaccharide vaccine is recommended for adults at increased risk for developing pneumococcal pneumonia including the elderly, people who havediabetes, chronic heart, lung, or kidney disease, those with alcoholism, cigarette smokers, and in those people who have had their spleen removed. This vaccination should be repeated every five to seven years, whereas the flu vaccine is given annually.

Antibiotics often used in the treatment of this type of pneumonia includepenicillin, amoxicillin and clavulanic acid (Augmentin, Augmentin XR), and macrolide antibiotics including erythromycin (E-Mycin, Eryc, Ery-Tab, PCE, Pediazole, Ilosone), azithromycin (Zithromax, Z-Max), and clarithromycin(Biaxin). Penicillin was formerly the antibiotic of choice in treating this infection. With the advent and widespread use of broader-spectrum antibiotics, significant drug resistance has developed. Penicillin may still be effective in treatment of pneumococcal pneumonia, but it should only be used after cultures of the bacteria confirm their sensitivity to this antibiotic.

Klebsiella pneumoniae and Hemophilus influenzae are bacteria that often cause pneumonia in people suffering from chronic obstructive pulmonary disease (COPD) or alcoholism. Useful antibiotics in this case are the second- and third-generation cephalosporins, amoxicillin and clavulanic acid, fluoroquinolones (levofloxacin [Levaquin], moxifloxacin-oral [Avelox], and sulfamethoxazole/trimethoprim [Bactrim, Septra]).

Mycoplasma pneumoniae is a type of bacteria that often causes a slowly developing infection. Symptoms include fever, chills, muscle aches,diarrhea, and rash. This bacterium is the principal cause of many pneumonias in the summer and fall months, and the condition often referred to as "atypical pneumonia." Macrolides (erythromycin, clarithromycin, azithromycin, and fluoroquinolones) are antibiotics commonly prescribed to treat Mycoplasma pneumonia.

Legionnaire's disease is caused by the bacterium Legionella pneumoniaethat is most often found in contaminated water supplies and air conditioners. It is a potentially fatal infection if not accurately diagnosed. Pneumonia is part of the overall infection, and symptoms include high fever, a relatively slow heart rate, diarrhea, nausea, vomiting, and chest pain. Older men, smokers, and people whose immune systems are suppressed are at higher risk of developing Legionnaire's disease. Fluoroquinolones (see above) are the treatment of choice in this infection. This infection is often diagnosed by a special urine test looking for specific antibodies to the specific organism.

Mycoplasma, Legionnaire's, and another infection, Chlamydia pneumoniae, all cause a syndrome known as "atypical pneumonia." In this syndrome, the chest X-ray shows diffuse abnormalities, yet the patient does not appear severely ill. In the past, this condition was referred to as "walkingpneumonia," a term that is rarely used today. These infections are very difficult to distinguish clinically and often require laboratory evidence for confirmation.

Recently, a study performed in the Netherlands demonstrated that adding a steroid medication, dexamethasone (Decadron), to antibiotic therapy shortens the duration of hospitalization. This medication should be used with caution in patients whom are critically ill or already have a compromised immune system.

Pneumocystis carinii (now known as Pneumocystis jiroveci) pneumonia is another form of pneumonia that usually involves both lungs. It is seen in patients with a compromised immune system, either from chemotherapy forcancer, HIV/AIDS, and those treated with TNF (tumor necrosis factor), such as for rheumatoid arthritis. Once diagnosed, it usually responds well to sulfa-containing antibiotics. Steroids are often additionally used in more severe cases.

Viral pneumonias do not typically respond to antibiotic treatment. These infections can be caused by adenoviruses, rhinovirus, influenza virus (flu),respiratory syncytial virus (RSV), and parainfluenza virus (that also causescroup). These pneumonias usually resolve over time with the body's immune system fighting off the infection. It is important to make sure that a bacterial pneumonia does not secondarily develop. If it does, then the bacterial pneumonia is treated with appropriate antibiotics. In some situations, antiviral therapy is helpful in treating these conditions. More recently, H1N1, swine-origin influenza A, has been associated with very severe pneumonia often resulting in respiratory failure. This disease often requires the use of mechanical ventilation for breathing support. Death is not uncommon when this infection involves the lungs.

Fungal infections that can lead to pneumonia include histoplasmosis, coccidiomycosis, blastomycosis, aspergillosis, and cryptococcosis. These are responsible for a relatively small percentage of pneumonias in the United States. Each fungus has specific antibiotic treatments, among which are amphotericin B, fluconazole (Diflucan), penicillin, and sulfonamides.

Major concerns have developed in the medical community regarding the overuse of antibiotics. Most sore throats and upper respiratory infections are caused by viruses rather than bacteria. Though antibiotics are ineffective against viruses, they are often prescribed. This excessive use has resulted in a variety of bacteria that have become resistant to many antibiotics. These resistant organisms are commonly seen in hospitals and nursing homes. In fact, physicians must consider the location when prescribing antibiotics (community-acquired pneumonia, or CAP, versus hospital-acquired pneumonia, or HAP).

The more virulent organisms often come from the health-care environment, either the hospital or nursing homes. These organisms have been exposed to a variety of the strongest antibiotics that we have available. They tend to develop resistance to some of these antibiotics. These organisms are referred to as nosocomial bacteria and can cause what is known as nosocomial pneumonia when the lungs become infected.

Recently, one of these resistant organisms from the hospital has become quite common in the community. In some communities, up to 50% of Staph aureus infections are due to organisms resistant to the antibiotic methicillin. This organism is referred to as MRSA (methicillin-resistant Staph aureus) and requires special antibiotics when it causes infection. It can cause pneumonia but also frequently causes skin infections. In many hospitals, patients with this infection are placed in contact isolation. Their visitors are often asked to wear gloves, masks, and gowns. This is done to help prevent the spread of this bacteria to other surfaces where they can inadvertently contaminate whatever touches that surface. It is therefore very important to wash your hands thoroughly and frequently to limit further spread of this resistant organism. The situation with MRSA continues to evolve. The community-acquired strain of MRSA tends to be responsive to some of the more commonly used antibiotics whereas the hospital-acquired strains require stronger, more aggressive antibiotic therapies. As this evolution occurs, patients are arriving in the hospital with the community-acquired strains as well as a previous hospital-acquired strain. This further necessitates performing bacterial cultures to determine the best course of action.

Source: http://www.medicinenet.com/pneumonia/