Neonatal meningitis due to Listeria or Group B Strep is commonly treated with ampicillin and gentamicin, an aminoglycoside antibiotic which carries a risk of ototoxicity. All aminoglycoside antibiotics bind to the prokaryocyte 30S ribosomal subunit in order to prevent initiation of protein synthesis.
Gentamicin is among the most widely used aminoglycoside and is frequently employed against nosocomial infections. Other examples of aminoglycosies include streptomycin, neomycin, and amikacin. Because aminoglycosides inhibit formation of the initiation complex, they disrupt translation of prokaryotic mRNA, which causes bacterial cell death (bactericidal). Ototoxicity is a potential side effect and administration of gentamicin to pregnant women has even resulted in cases of fetal ototoxicity.
Hamilton and John review evolving management of febrile neonates and young children. With the advent of HiB and pneumococcal vaccinations, the etiology of fever has changed. Although neonates still need an exhaustive workup, chest x-rays and lumbar puncture are not recommended in older children who fail to meet other clinical risk criteria.
Gromadski and Rodnina illuminate the mechanism by which another aminoglycoside, streptomycin, interferes with protein synthesis. Streptomycin binds to the 30S ribosomal subunit in order to cause loss of codon selectivity in the ribosome.
Illustration A shows the mechanism by which aminoglycosides interfere with protein synthesis.
Answer 1, 2, 5: Aminoglycosides bind to the 30s subunit, not the 50S. Macrolide antibiotics, such as azithromycin, bind to the 50S subunit.
Answer 4: Aminoglycosides, such as gentamicin bind irreversibly to the 30S subunit. Doxycycline is an example of an antibiotic which binds reversibly to the 30S subunit.
Hamilton JL, John SP. Evaluation of fever in infants and young children. Am Fam Physician. 2013 Feb 15;87(4):254-60. Review. PubMed PMID: 23418797
PMID:23418797 (Link to Abstract)
Gromadski KB, Rodnina MV. Streptomycin interferes with conformational coupling between codon recognition and GTPase activation on the ribosome. Nat Struct Mol Biol. 2004 Apr;11(4):316-22. Epub 2004 Mar 7.
PMID:15004548 (Link to Abstract)