Preventative antibiotics and other antimicrobials

Penicillins are a class of antibiotics that includes penicillin, amoxicillin, and combinations of penicillins with other drugs that help them work better, such as amoxicillin-clavulanate (trade name Augmentin). They are well tolerated long term and protect against Streptococcus pneumoniae and other common gram-positive bacteria that cause pneumonia, ear infections, and sinusitis. They may also be used to prevent infection when undergoing treatment for gum disease.

Penicillin can cause allergic reactions such as diarrhea, rash, or anaphylaxis (rapid heartbeat, low blood pressure, and difficulty breathing), which is a medical emergency. If you experience these symptoms, it’s important to get tested for penicillin allergies as well as getting medical attention. Healthcare providers test for penicillin allergy by putting a small dose of penicillin in the skin with a needle and looking for red, itchy bumps or by giving five doses of penicillin, starting with a small dose and increasing it to see if there is a reaction. Note that many people with a reported allergy to penicillin are not found to be allergic through testing [4].

Trimethoprim-sulfamethoxazole (TMP-SMX; trade names Bactrim, Septra) is mostly prescribed for people with CGD and Wiskott-Aldrich syndrome (WAS). It is very well tolerated long term and doesn’t cross-react with other antibiotics. It protects against some methicillin-resistant Staphylococcus aureus (MRSA), a gram-positive bacteria, and the gram-negative Serratia marcescens and Burkholderia cepacia complex bacteria. One study found that prophylactic TMP-SMX decreased non-fungal infections in CGD by up to one third [5].

TMP-SMX also acts as an antifungal against pneumocystis pneumonia (PCP), a severe lung infection caused by the fungus Pneumocystis jirovecii. Dosing to prevent bacterial infections is typically higher than dosing to prevent Pneumocystis infections.

TMP-SMX can cause allergies, but an allergist can help a person become less sensitive to it. Rarely, it can cause blood disorders if it’s used at high doses or liver problems.

Azithromycin (trade names Zithromax, Zmax, Z-Pak) is well tolerated and good at preventing chronic sinus infections. It protects against gram-positive Streptococcus spp. and gram-negative Haemophilus influenzae. It works especially well against Mycobacterium spp., which are gram-positive bacteria that live in the soil and cause infections in people with certain PIs such as CGD. Azithromycin has also been shown to have anti-inflammatory properties in patients with cystic fibrosis and chronic obstructive lung disease [6], and helps prevent worsening of bronchiectasis.

A 2019 study showed that people with antibody deficiencies who had chronic, infection-related lung disease had positive results with azithromycin prophylaxis [7]. Those treated had a lower risk of symptoms getting worse, improved quality of life and lung function, lower risk of hospitalizations, and needed fewer additional antibiotics.

Side effects from azithromycin include nausea and diarrhea. In rare cases, it can cause heart rhythm problems such as a prolonged QT interval. People with an irregular heartbeat or other risk factors for heart arrhythmias should not use azithromycin or other antibiotics in the same class, known as macrolide antibiotics, and those on macrolides long term should be monitored for an irregular heartbeat [8].

Another problem with azithromycin is that the gram-positive bacteria Streptococcus pneumoniae and Staphylococcus aureus can easily become resistant to it.

Erythromycin and roxithromycin are two other prophylactic antibiotics commonly prescribed for chronic sinusitis. They prevent infections caused by gram-positive bacteria like Staphylococcus aureus and Streptococcus pneumoniae and gram-negative bacteria like Haemophilus influenzae and Moraxella catarrhalis.

Acyclovir is good at preventing infection from the herpes simplex virus, which causes cold sores or genital herpes, and the varicella-zoster virus, which causes shingles and chickenpox. The drug is very well tolerated and people can be on it for many years. It is often used for those with T cell deficiencies, like severe combined immunodeficiency (SCID) and combined immunodeficiencies (CID), such as GATA2 and DOCK8 deficiency.

Like acyclovir, valacyclovir is good at preventing infection from the herpes simplex virus and the varicella-zoster virus, and is well tolerated. It is also used for those with T cell deficiencies.

Oseltamivir (trade name Tamiflu) can be used as a prophylaxis for infection from the influenza virus.