Antibiotics Penicillin

Mechanism of Action

Penicillin G, when injected into the patient, will act against actively proliferating penicillin-sensitive strains of bacteria (Drugs.com, 2011). This does not include several strains of staphylococci producing penicillinase or bacteria that are quiescent. The mechanism of action is inhibition of cell-wall mucopeptide biosynthesis. Penicillin G. works best against staphylococci groups A, B, C, G, H, L, and M, pneumococci, Neisseria meningitides, Neisseria gonorrhoeae, Treponemapallidum, and many others.

Clinical Uses

Penicillin is used to treat serious infections, such as septicemia, pneumonia, endocarditis, pericarditis, empyema, and meningitis (Drugs.com, 2011). Penicillin is also indicated in cases of anthrax, botulism, actinomycosis, diphtheria, listeria infections, erysipelothrix endocarditis, severe infections of the oropharynx, lower respiratory tract, and genitals. Penicillin is also used to treat gonorrhea, syphyilis, rat-bite fever, and Haverhill fever. Only penicillin-sensitive bacteria should be treated due to the risk of creating penicillin-resistant strains. Although treatment should begin immediately in urgent cases, the sensitivity of the infectious agent should be determined in all cases to prevent the development of drug-resistant strains.

Adverse Effects

Penicillin should be used cautiously in individuals with a history of allergic disease and should an allergic reaction occur, it use should be discontinued, unless penicillin is the only viable treatment for a life-threatening condition (Drugs.com, 2011). The estimated prevalence of penicillin allergy is between 0.7 to 10%. In patients with syphilis or other spirochetal infections, the following may occur within two hours and resolve within 24 hours: fever, chills, myalgias, headaches, tachycardia, hyperventilation, and vasodilation. This may be due to the release of pyrogens into the system. Gastrointestinal distress can occur: nausea, vomiting, stomatitis, and black or hairy tongue. High doses in renal patients can cause hemolytic anemia, serious or fatal electrolyte imbalances (due to sodium content), congestive heart failure, kidney damage, seizures, and coma.

Gentamicin

Mechanism of Action

Gentamicin belongs to a class of antibiotics defined by an aminoglycoside group (Drugs.com, 2014a). Gentamicin is harvested from the Micromonospora purpurea cultures. The bactericidal activity of gentamicin depends on the binding of the aminoglycoside group to bacterial ribosomes,...

Gentamicin is active against both Gram-positive and -negative organisms.
Clinical Uses

As with most antibiotics, the use of gentamicin should be based on culture results and local epidemiological data to minimize the emergence of drug-resistant strains (Drugs.com, 2014a). Gentamicin is effective against sensitive strains of Pseudomonas aeruginosa, indole-positive and -negative strains of Proteus species, Escherichia coli, Klebsiella-Enterobacter-Serratia species, Citrobacter species, and coagulase-positive and -negative Staphylococcus species. Common uses include serious cases of neonatal sepsis, meningitis, and infections of the urinary, respiratory, and gastrointestinal tracts.

Adverse Effects

Given Gentamicin's toxicity, its use in initial urinary tract infections is not recommended unless the organism is resistant to less toxic antibiotics and susceptible to gentamicin (Drugs.com, 2014a). The organs affected by gentamicin toxicity include kidneys and the nervous system. Neurotoxicity is most common in patients with impaired renal function and can lead to the development of dizziness, vertigo, tinnitus, irreversible hearing loss, and other auditory problems. Peripheral neurotoxicity can cause numbness, tingling, twitching, convulsions, and Myasthenia gravis-like symptoms.

Azithromycin

Mechanism of Action

The bactericidal activity of azithromycin results from binding to prokaryotic 23S ribosomal RNA, thereby inhibiting assembly of the 50S ribosomal unit and subsequent translation (Drugs.com, 2014b). The distribution of the drug to sites of infection may be mediated by the accumulation within phagocytes, at levels 30-times higher than in serum.

Clinical Uses

Azithromycin is recommended for routine treatment of adult airway infections, including patients suffering from community-acquired pneumonia and chronic obstructive pulmonary disease (Drugs.com, 2014b). Azithromycin treatment is contraindicated in patients with hospital-acquired pneumonia, cystic fibrosis, bacteremia, or who require hospitalization. Other uses include treatment of uncomplicated skin infections, urethritis, cervicitis, and genital ulcers. Similar uses are recommended for pediatric patients.

Adverse Effects

The most common adverse effect of azithromycin treatment is caused by multiple-dose regimens, which can lead to the development of gastrointestinal symptoms, including nausea, vomiting, diarrhea, and stomach pain (Drugs.com, 2014b). Rare side…