Pneumonia is the infection of the lungs. It's usually a result of primary infection of the upper respiratory tract. It can be bacterial or viral but rarely is it parasitic.
The most common bacterial cause of pneumonia is streptococcus pneumonia and chlamydia pneumonia. Viral pneumonia occur due Respiratory Syncytial Virus, Influenza and Par influenza virus. Fungal pneumonia can occur though it's equally rare as parasitic infection.
Leading causes of pneumonia
- Rhino virus infection. Pneumonia occur after primary rhinitis has disseminated to the lungs.
- Respiratory syncytial virus. Cause upper respiratory infection followed by the dissemination to the lungs
- Pneomocytis pneumonia
- Streptococcus pneumoniae
- Mycoplasma pneumonia
- Legionella bacteria
- Human parainfluenza virus (HPIV)
1.0 Chlamydia pneumonia
This pneumonia is caused by bacterial agent chlamydia pneumonia. It's treated using various class of drugs
They are made up of macro cyclic lactone ring in which it may be attached to clamidinose or cladinose sugar. It's a group of natural antibiotics. The mode of action of macrolide is the inhibition of protein synthesis. They bind to the enzyme peptidyltransferase preventing them from adding peptides together. This will lead to the termination of the protein synthesis thus the bacteria dies.
They also act by inhibition of the enzyme peptidyl-tRNA. They inhibit the dissociation from the ribosome.
They also act by binding to the 50S subunits of the amino acid at the P site of the bacterial ribosome. This action inhibits protein synthesis of proteins and is bacteriostatic.
On administration of macrolide they usually bind and concentrate on the white blood cells and are transported together to the site of infection.
Example of macrolide are azithromycin which is very effective to chlamydia pneumonia. Azithromycin is the first drug administered to the patient.
They also act by inhibition of protein synthesis in bacteria. However instead of binding to the S site of ribosome the bind to the A site of the ribosome 30S subunit preventing the attachment of aminoacyl-tRNA. This eventually leads to the prevention of addition of amino acid to the growing peptide chain. However the action of the drug is potent only when administered and reverses when the drug is withdrawn. These drugs are less effective in humans as they also act on human ribosomal subunits.
It's used in treatment of chlamydia pneumonia and is the first line of treatment of Mycoplasma pneumoniae.
The spectrum of the antibiotic is broad acting on a number of other bacteria apart from chlamydia pneumoniae and mycoplasma pneumoniae. It's very good drug by the fact that it treats penicillin resistant infections.
2.0 Treatment of streptococcus pneumoniae
Streptococcus pneumoniae can be treat in various ways. The most important is the prevention. This is acquired through vaccines. Treatment is through use of antibiotics.
The world through WHO has initiated a massive worldwide vaccination against streptococcus pneumonia as the first step to elimination of pneumonia. This include the use of PCV especially in the USA and in Europe.
Antibiotic treatment of streptococcal pneumonia
Levofloxacin is usually used for treatment of streptococcal pneumonia. It's a flouroquinolone which act by inhibition of protein synthesis in bacteria. It's mostly used in treatment of streptococcal infections that has resistant to penicillin drug.
Penicillin is another choice of first line of drug if the bacteria is penicillin susceptible. A minimum inhibitory concentration (MIC) of 2mcg/ml is administered. Alternatively penicillin G or amoxicilin may be use.
The mode of action of penicillin and other beta lactam antibiotics. They inhibit the growth of peptidoglycan in the bacterial cell wall during the process of bacterial remodeling. They bind to the enzyme DD- transfer peptidase inhibiting their function of catalyzing the formation of the bacteria peptidoglycan cross linkage. This leads to death of the bacterial cell hence elimination of the infection. They also enable the penetration of the aminoglycosides into the bacterial cell thus co administration of the two drug is worthwhile.
Vancomycin and linezolid
It's an alternative therapy in case of penicillin resistance. A broad spectrum antibiotic that is used for the treatment. The dosage should be quite high 3g/day with an MIC greater than 4 microgram/ml.
These drugs act by inhibiting the process of formation of secondary bacterial cell wall. This makes the bacterial cell wall to lack integrity and thus easily lysed and phagocytized. In treatment of streptococcus infection.
This disease is prevented by the use of influenza vaccine which is highly effective in prevention of new infections. Hib vaccine is present and is recommended to each one of us. However in infection the vaccine is of very little help.
Beta lactamase haemophilus influenza is treated by use of amoxilicin antibiotic. It has the same mode of action as that of penicillin i.e. they act on the bacteria at the stage of highest dividing state by preventing cross linkage of peptidoglycan.
This is another causative agent of pneumonia. It's mainly treated by administration of flouroquinole antibiotics such as azithromycin as the first line therapy. Alternative drugs is doxycycline.
They both have the same mode of action in that they prevent cellular protein synthesis by binding to the 30S subunit of ribosome leading to death of the cell i.e. bactericidal.
Viral pneumonia treatment
There are various etiological agents that are because viral pneumonia in man and are all managed in a similar way.
The first mode of prevention of viral pneumonia is the administration of vaccine. The available vaccines are influenza vaccine.
Chemoprophylaxis may also be done using oseltamivir and zanamivir.
Treatment therapy include administration of oseltamavir, peramivir and zanamavir
Oseltamivir mode of action
Oseltamivir is a pro drug. A pro drug is a biological substance that mimics the cellular protein or amino acid and can be utilized by the cell, however, it's always inactive. It's an ethyl ester compound. It inhibits the function of neuraminidase enzyme by competing with it for the binding site. They thus prevent new virions from being released thus preventing continuous infection.
Both peramivir and zanamivir are also prodrugs which inhibit neuraminidase enzyme preventing release of virions.
Mainly the treatment of influenza pneumonia is use of antibiotics. Also, the patients are given supportive treatment trough administration of analgesia and anti-pyretic.
Act mainly by preventing inhibition of the M2 proton channel. This results to inhibition acidification of the cell because there is no hydrogen transport to the cell. This acidification leads to dissociation of the ribonucleoproteins initiating viral replication. The drug will prevent acidification of the cell thus inhibiting replication of influenza virus. This drug has a limited spectrum to influenza a virus alone. They can also be used for prevention.
Pneumonia caused by Respiratory syncytial virus
Treatment is supportive in nature in uncomplicated state. The drug of choice for treatment of RSV pneumonia is Ribavirin. Ribavirin act by interference of viral transcription process. It's a nucleoside analogue of guanosine. During virus replication process the virus incorporates ribavirin in the growing chain of amino acid. Ribavirin is uncomplimentary to other guanosine and thus there will be a premature stoppage of synthesis of viral amino acid. This lead to failure of formation of the virions subsiding replication hence infection.
It's recommended that the drug be given to those who are severely sick and high dose of 60mg/ml for two hours aerosol can be given to the patient.
This is an immunoglobulin produced by DNA recombination technique that is used for treatment of RSV. It's of importance especially in infants who are premature and born with other lung diseases or pneumonia. A combination of oral Ribavirin and aerosolize synagis is used to test complicated patient and high risk patients. The use of this drug regimen is not globally recognized or recommended by Food and drug association (FDA).
The main drug for treatment of adenovirus associate pneumonia is intravenous administration of CIdofovir. Cidofovir is an inhibitor of viral DNA polymerase enzyme. By binding to the viral DNA polymerase enzyme it inhibits the synthesis of viral DNA thus leading to stoppage of viral replication. Of great importance is to note that Cidofovir also binds to human DNA but the action on human genome is greatly reduced.
It's highly effective to adenovirus serotype 14. Its administration is best suited for imunocompromised people. Epidemiological study show a variation of in vitro action on adenovirus for instance species C was shown to be more sensitive than other species.
Pneumonia due to parainfluenza
Oral administration of ribavirin and aerosolized ribavirin inhalation together with in vitro ribavirin are effective against parainfluenza pneumonia. They are also effective in immunocompromised individuals and is highly recommended for use by high risk individual.
Herpes simplex pneumonia (HSV)
Intravenous administration of 250mg of acyclovir is quite effective to HSV and is the most current choice of treatment. Acyclovir mode of action is inhibition of the viral DNA synthesis by acting on the viral DNA polymerase enzyme inhibiting the binding of the nucleotides to it.
It should be noted that sometimes there may be occurrence of concomitant bacterial infection with HSV thus should be supplemented by other broad spectrum anti biotic.
Corona virus associated pneumonia
Pneumonia is associated with severe acute respiratory syndrome corona virus (SARS-CoV) the main drugs used in treatment of this type of pneumonia are protease inhibitors which include lopinavir and ritonavir.
These drug act by inhibiting the function of the enzyme protease by inhibiting a liver enzyme that synthesizes the enzyme cytochrome P450-3A4 (CYP3A4), which synthesizes protease inhibitor. The drug is usually used in low dose.
Note that ribavirin is not active against SARS-CoV nod thus not recommended for use.
Measles associated pneumonia
Treatment is generally supportive by use of analgesics and antipyretic drugs. Of great concern however is the immunocompromised individuals and the infants. They should be administered with a dose of ribavirin intravenously at a dose of 20-35mg/kg body weight daily for a week.
Varicella zoster associated pneumonia
Basically treatment is supportive first by treating the skin lesions using anti-retroviral drugs and monitoring systemic infection by administration of antipyretic drugs to monitor fever. Acyclovir should administered to patients who are imunnopcomromised.
Is the infection of the lungs by fungal agents? This is usually as a result of opportunistic infections and rarely endemic infections. It has high fatality rate of about 90%.
Treatment is mainly done by surgery to remove anti-fungal agents i.e. fungal debriment or by use of anti-fungal drugs
Caused by parasitic infection of the lungs and is usually transient in nature due to migration of the parasite in their life cycle process. These parasite include Ascaris lumbricoides and pragnonimus westermani.
Treatment is by administration of anti-parasitic agents and removal of the parasite from the lungs through aspiration and surgery.
Treatment is also symptomatic and supportive in nature.
Community acquired pneumonia
This is pneumonia acquired outside the hospital environment. It usually occur two days after the admission to hospital. These type of pneumonia is among the greatest reported pneumonia in the USA and is as a result of a many pathogenic microorganism such as E. coli, streptococcus pneumoniae among others. These patients should be treated according to the type of etiological agent that cause the pneumonia after laboratory investigation. Recommendations and guidelines should also be followed in the management of this patients. These include supportive treatment, use of antiviral drugs, antibacterial drugs and broad spectrum antibiotics.
Hospital acquired pneumonia
Also known as nosocomial pneumonia. They are due to staphylococcus or pseudomonas bacteria and are beta lactam resistant thus not treated with penicillin. Its pneumonia acquired after 48 hours of admission to hospital. It's usually complicated and they need a comprehensive cover of methicillin resistance staphylococcus aureus. They are treated with vancomysin or linezolid therapy.