An Overview of Antimicrobials in Pneumonia Pharmacotherapy

During a presentation at the American Association of Pharmacy Technicians 2022 Annual Pharmacy Technician Convention, Andrew Darkow, PharmD, MBA, BCPS, clinical assistant professor at Campbell University and internal medicine clinical pharmacist at Duke Regional Hospital, discussed antibiotic use for pharmacists and an overview of pneumonia pharmacotherapy.

Bacteria does not always have to be bad. In fact, Darkow noted the highest number of bacteria in humans is in the gut, which aids in digestion, prevents harmful infection, and helps immunity. Bacteria can either be commensal or pathogenic and can be identified with a variety of tests, including gram stain, enzyme tests, hemolysis, and more.

The most common way to detect bacteria and determine the right medication to use is with the gram stain test, which will show whether the bacteria is gram-positive or gram-negative. Gram-positive bacteria contain multiple peptidoglycans and a cytoplasmic membrane but does not have an outer membrane or lipopolysaccharide layer, which gram-negative bacteria has, with only 1 peptidoglycan.

Different antibiotics use different techniques to kill or prevent growing bacteria that causes diseases. Antibiotics often work differently than other medications, in that they eradicate bacteria instead of changing the body, such as blood pressure or diabetes medications.

“What's interesting about antibiotics is they're not causing a change directly to our body, or at least the intention is to eradicate the bacteria,” Darkow said in the presentation. “Bacteria has many different components, and so we can take advantage of that by using different mechanisms to target those different components.”

When there are gram-positive bacteria, vancomycin, daptomycin, and linezolid are typically used. When there are gram-negative bacteria, tobramycin, amikacin, gentamicin, and aztreonam are used.

However, there are also antibiotics that can treat both gram-positive and gram-negative bacteria, including penicillin, clindamycin, azithromycin, some sulfa drugs, and fluoroquinolones.

Bacteria can also develop resistance to antibiotics, so decreasing unnecessary antibiotics, using the proper dosages, using the shortest effective duration, and using the most appropriate antibiotic for the type of bacteria can help to reduce resistance.
“We need to try to use antibiotics appropriately to help avoid these downstream consequences, such as decreasing unnecessary antibiotic use. If we don't think that the patient has an infection or we think that they're infection may be viral in nature, an antibiotic isn't going to help them,” Darkow said in the presentation.

Darkow went on to discuss how to treat pneumonia, which is an infection that inflames 1 or both lungs and can cause shortness of breath, fever, chills, and difficulty breathing.

He said that it is essential to identify the type of pneumonia first, which includes community-acquired pneumonia, hospital-acquired pneumonia, ventilator-acquired pneumonia, and aspiration-acquired pneumonia, which occurs when you inhale, food, drink, vomit, or saliva into your lungs.

Darkow touched briefly on categorizing COVID-19 pneumonia, saying there are specific guidelines and treatments that had been FDA-approved or given emergency use authorization.

To diagnose pneumonia, using a chest x-ray is the gold standard, but other methods, such as blood cultures and sputum gram stain and culture, can be used to identify a pneumonia infection.

Once the type of pneumonia is identified, the next step is to identify the pathogen, Darkow said. These can include respiratory pneumonia, strep pneumoniae, haemophilus influenza, mycoplasma pneumonia, chlamydia pneumonia, and legionella pneumonia, with the last 3 lacking cell wells that can help determine the type of antibiotic to use.

Darkow said that physicians can prescribe azithromycin, amoxicillin, and doxycycline to patients who are outpatient and do not have comorbidities. If there is a presence of comorbidities, such as heart disease, lung disease, liver disease, or diabetes, physicians typically prescribe Augmentin or cephalosporin, which both target cell walls, with a macrolide or doxycycline, which do not target cell walls.

Additionally, physicians can prescribe respiratory fluoroquinolone and levofloxacin and moxifloxacin.

Darkow did note that azithromycin is not always sufficient in cases of pneumonia.
For inpatients, if a patient does not have a severe infection, beta-lactam and macrolide can be used with the addition of respiratory fluoroquinolone. For severe patients, beta-lactam and macrolide of beta-lactam and fluoroquinolone can be used.

If the patient has prior respiratory isolation of methicillin-resistant Staphylococcus aureus (MRSA), a type of bacteria resistant to some antibiotics, or present with organ function that has been dysregulated, physicians can add MRSA coverage, such as vancomycin, linezolid, Bactrim, or clindamycin.

Darkow continued by saying that there should be de-escalation of antibiotics to prevent resistance, such as patient counseling and switching from intravenous drugs to oral drugs. He concluded his presentation by emphasizing the importance of getting vaccinated again pneumonia.

“For our patients that it is appropriate for, we want to recommend pneumococcal vaccines,” Darkow said in the presentation. “[We] recommend [it] for all children who have not been previously vaccinated, or with certain medical conditions, specifics schedules, adults [with] a specific condition and it's recommended to get vaccine before age 65.”

Reference

Darkow AT. Simplifying antibiotics: a review of antimicrobials with a focus on pneumonia pharmacotherapy. Raleigh-Durham, NC: AAPT 2022 Annual Pharmacy Technician Convention; July 22, 2022.