Narrow-spectrum Vs. Broad-spectrum Antibiotics: A Comparative Analysis

Narrow-spectrum Vs. Broad-spectrum Antibiotics
The difference between narrow-spectrum and broad-spectrum lies in the range of bacteria that the antibiotic can act on. The latter class of antibiotics are better at treating different types of bacterial infections.
HealthHearty Staff
Last Updated: Apr 22, 2018
Did You Know?
In recent times, the increasing cases of antibiotic resistance is alarming, and has been described as one of the world's most pressing public health issues.
Antibiotics prescribed for a bacterial infection can either be a broad-spectrum or a narrow-spectrum antibiotic, depending upon its efficacy in targeting the different types of bacteria. We usually notice that a doctor prescribes an antibiotic even without conducting a blood test to identify the type of bacteria. In these cases, the medication given is a broad-spectrum antibiotic which works against a larger group of bacteria.

The following sections elaborate more on the differences between narrow-spectrum and broad-spectrum antibiotics. This comparison of differences will allow us to understand the details of both types in a better and easier way.
In case of narrow-spectrum antibiotics, the range of bacteria that are targeted by the medication is fairly small. These antibiotics are designed only to treat a specific type of bacteria.
Broad spectrum antibiotics are formulated to destroy a large number of different types of bacteria. They are effective against a wide range of infections caused by a variety of bacteria. So, illnesses caused by both gram-negative and gram-positive bacteria can be effectively treated with these antibiotics. They are designed to attack several strains and species of bacteria.
The best example of a narrow-spectrum antibiotic is sodium fusidate, which is formulated to destroy staphylococcal strains of bacteria. Azithromycin, clarithromycin, clindamycin, erythromycin, and vancomycin are some of the medications that belong to this class of antibiotics.
The best example here is amoxicillin, which is effective against a wide spectrum of bacteria, including Helicobacter, Streptococcus, Moraxella, Enterococcus, Bacillus subtilis, and Haemophilus. Another example is tetracycline, which is effective against a variety of bacteria that cause UTIs, skin infections such as acne, respiratory tract infections, strep infections, and even lyme disease. Other examples include amoxicillin, gatifloxacillin, levofloxacin, and streptomycin.
One cannot rule out the possibility of bacteria becoming resistant to narrow-spectrum antibiotics. The reason for this is that these types of antibiotics target only a specific group of bacteria.
These are designed to attack a larger group of bacteria, so they are particularly useful in treating diseases caused by bacteria that are resistant to narrow-spectrum antibiotics.
Narrow-spectrum antibiotics are not helpful in treating infections that are caused by multiple types of bacteria.
Often, it is not just one type of bacteria that causes the infection. In such cases, broad-spectrum antibiotics would be recommended to treat such a 'super' infection.
Blood Test
A blood test is usually ordered before prescribing a narrow-spectrum antibiotic. After the test points toward a specific type of bacteria, the doctor would prescribe an antibiotic that is specifically formulated for that particular infection.
A major advantage here is that a blood test to find out the causative agent is not necessary. Even without diagnosis, broad-spectrum antibiotics, in most cases, work against the infection. For instance, a serious bacterial illness such as meningitis requires urgent medical attention. One simply cannot wait for a blood test. Here, doctors prefer to skip the testing and prescribe a broad-spectrum antibiotic to treat the infection.
Antibiotic Resistance
Narrow-spectrum antibiotics are not prescribed as frequently. Due to this fact, bacteria are found to be less resistant to this class of antibiotics.
People put on these antibiotics are at an increased risk of becoming resistant to these drugs. Though they work against a range of bacterial attacks, the growing number of cases of bacteria surviving treatment with these antibiotics is worrying.
On the whole, when narrow-spectrum antibiotics show no success in treating an infection, resorting to broad-spectrum antibiotics remains the only option. In order to tackle this menace of drug-resistant bacteria, it is necessary to avoid overuse of antibiotics. Popping pills at will won't address the issue, and will only make the bacteria stronger against them. So avoid misuse and take medications only when prescribed.