Aminoglycosides and Streptogramins Quiz

Arbekacin targets both the 30S and 50S ribosomal subunits in bacteria, disrupting protein synthesis. It also directly damages bacterial membranes, leading to a dual attack on bacterial cells.

Arbekacin is resistant to inactivation by enzymes that normally break down other aminoglycosides, making it effective against bacteria that have developed resistance to those antibiotics.

Arbekacin, when used against MRSA infections, effectively disrupts the biofilm structure and reduces inflammation. This leads to eradication of the biofilm and resolution of the infection.

Arbekacin is highly effective against MRSA and other resistant Staphylococcus and Enterococcus species. It also shows activity against some resistant Pseudomonas aeruginosa and Acinetobacter baumannii strains.

Tobramycin, Gentamycin, and Arbekacin are all effective against Pseudomonas infections.

Streptomycin, Kanamycin, and Amikacin are effective against Mycobacterium tuberculosis infections.

Aminoglycosides are often combined with beta-lactams or glycopeptides (like cephalosporins or penicillin) to enhance their effectiveness against Gram-positive bacteria. This synergistic effect increases the permeability of the bacterial cell wall, allowing greater entry of aminoglycosides.

Tetracyclines are a group of bacteriostatic antibiotics with a broad spectrum of activity against Gram-positive and Gram-negative bacteria, as well as certain pathogens like Rickettsia and Chlamydia.

They are named for their four hydrocarbon rings.

They reversibly bind to the 30S ribosomal subunit of bacteria, preventing the addition of amino acids to the growing peptide chain, thereby inhibiting protein synthesis.

Tetracyclines are active against multiplying bacteria, effectively stopping their growth and preventing further spread of infection.

Tetracyclines are bacteriostatic, meaning they inhibit bacterial growth but don't directly kill them. However, at high dosages, they can exhibit bactericidal activity.

Tetracyclines have a broad spectrum of activity, meaning they can target a wide range of bacteria, including both aerobic and anaerobic, Gram-positive and Gram-negative types.

They penetrate bacterial cells using both passive and active mechanisms, depending on their hydrophilicity and energy dependence.

Tetracyclines are used to treat a variety of infections caused by susceptible bacteria.

They are effective against a wide range of bacteria, including those responsible for acne, Lyme disease, and certain sexually transmitted infections.

A group of antibiotics with a broad spectrum of activity, including against some resistant strains like Acinetobacter spp. They are primarily used for treating complicated intra-abdominal infections. Eravacycline is administered intravenously.

A third-generation tetracycline antibiotic with broad-spectrum activity, including against anaerobic bacteria. It's available in both oral and IV formulations.

A fourth-generation tetracycline with a narrow spectrum of activity. It's specifically used for treating moderate to severe acne vulgaris. Sarecycline is administered orally.

A family of antibiotics characterized by their macrocyclic lactone rings and deoxy sugars. Erythromycin is a naturally occurring macrolide, often used for patients allergic to penicillin. Derivatives include clarithromycin, ketolides, and azithromycin.

Macrolide Antibiotics are active against which bacterial groups?

Resistance mechanisms for third-generation tetracyclines include upregulation of the multidrug efflux system AcrA-AcrB-TolC and presence of adeB genes in VRE and CRE.

Ribosome protective proteins (RPPs) and mutations in 16SRNA contribute to resistance against Omadacycline.

The narrow spectrum of Sarecycline minimizes the impact on gut microbiota, leading to fewer gastrointestinal side effects.

Eravacycline is primarily used for treating complicated intra-abdominal infections (anaerobes).

Sarecycline is specifically used for treating moderate to severe acne vulgaris.

Quinupristin binds to the 50S ribosomal subunit, preventing polypeptide elongation and causing incomplete chains to be released. It acts similarly to macrolides but is bactericidal against Staphylococcus and most organisms except Enterococcus faecium. A prolonged post-antibiotic effect lasts up to 10 hours for Staphylococcus aureus.

Resistance to Streptogramin B can arise from two main mechanisms: Hydrolysis of the antibiotic by the vgb gene, initially observed in Staphylococcus aureus, or modification of the ribosomal target by a 23S rRNA methylase encoded by the ermB gene, leading to the MLSB phenotype.

The MLS (Macrolides-Lincosamides- Streptogramins B) resistance is observed primarily due to three mechanisms: 1. Methylation of rRNA (target modification), 2. Active efflux (M and L only), 3. Inactivation of the antibiotic (M and L only).

The most prevalent resistance phenotype is MLSB (constitutive or inducible), mainly attributed to the presence of ermA and ermC genes. This phenotype shows cross-resistance to Macrolides, Lincosamides, and Streptogramin B.

ErmA and ErmC genes are responsible for encoding proteins that modify the ribosomal target, leading to the MLSB phenotype, where bacteria become resistant to Macrolides, Lincosamides, and Streptogramin B.

Chloramphenicol binds to the bacterial 50S ribosomal subunit preventing the attachment of aminoacyl tRNA to the 50S subunit, thus inhibiting protein synthesis.

It is primarily bacteriostatic, meaning it inhibits the growth of bacteria, but can be bactericidal, meaning it kills bacteria, against certain strains like H. influenzae, N. meningitidis, N. gonorrhea, and Bacteroides fragilis.

Effective against a wide range of bacteria including S. epidermidis, S. aureus, M. pneumoniae, L. monocytogenes, Corynebacterium diphtheriae, P. multocida, Salmonella sp., Shigella sp., E. coli, Rickettsia and Anaerobes.

Chloramphenicol is not effective against Chlamydia infections.

Chloramphenicol is more effective than Tetracyclines in treating Typhoid Fever and other Salmonella infections.

Chloramphenicol can treat serious rickettsial infections like typhus and Rocky Mountain spotted fever.

Chloramphenicol is an alternative to beta-lactams for treating meningococcal meningitis in patients allergic to penicillin.

Chloramphenicol is used as a last resort for severe infections caused by Salmonella Typhi and Paratyphi.

Chloramphenicol can be used to treat infections caused by anaerobes, such as Bacteroides.

Chloramphenicol should be used with caution due to its potential for serious side effects, such as aplastic anemia.