QUESTION: Which of the following is not a broad spectrum antibiotic?
A Tetracycline
B Chloromycetin
C Penicillin
D None of these
ANSWER: Penicillin
| Aspect | Broad-Spectrum Antibiotics | Narrow-Spectrum Antibiotics |
| Range of coverage and usage | · These antibiotics target a wide range of bacteria, including both Gram-positive and Gram-negative species.
· Used when the infecting bacteria are unidentified or when a mixed infection is suspected. |
· These antibiotics target only a specific group or species of bacteria.
· Used when the infecting bacteria are known or when a specific pathogen is suspected. |
| Mode of Action | · Target common bacterial functions shared by many species. | · Target specific cellular components or processes of certain bacteria. |
| Risk of Resistance | · High risk of promoting antibiotic resistance due to killing both harmful and beneficial bacteria. | · Lower risk of promoting antibiotic resistance, as they target specific bacteria. |
| Impact on Microbiota | · May disrupt the balance of normal gut flora, leading to secondary infections. | · Less likely to disrupt the normal microbiota. |
| Clinical Indications | · Often used in severe infections or when the causative bacteria are unknown. | · Typically used for targeted infections where the causative agent is known. |
| Examples | · Ciprofloxacin
· Amoxicillin · Clavulanate · Tetracycline · Chloromycetin |
· Penicillin
· Erythromycin used for Gram-positive bacteria |
| Advantages | · Can provide broad coverage in emergency situations. | · Reduces the risk of antibiotic resistance and minimizes collateral damage to microbiota. |
| Disadvantages | · Can lead to antibiotic resistance and superinfections. | · May not be effective if the infecting pathogen is not within their spectrum. |
| Cost and Availability | · Generally more expensive and widely available. | · Often less expensive and may have more limited availability. |
| Applicability in Immunocompromised Patients | · Often used when the immune system is compromised and the risk of opportunistic infections is high. | · May be preferred to avoid disrupting the weakened immune system. |