What drugs cover Pseudomonas aeruginosa? What drugs cover MRSA? These are two of the most important bacterial pathogens to cause healthcare-associated infections today. To help answer these questions, here is a study list of antibiotics that can cover Pseudomonas and/or MRSA.
Authored by: Timothy P. Gauthier, Pharm.D., BCPS-AQ ID
Last Updated: 25 April 2021
Many pharmacy students are introduced to antimicrobial spectrum of activity basics through microbiology coursework. During this time it is common for the student to receive a somewhat overwhelming amount of information and little guidance on the relative clinical importance of the material. In my experience this is partly driven by non-clinician instructors being responsible for many university-level microbiology courses.
As students move into higher-level classes, if they cannot adequately identify and define previously covered content, they are likely to find it difficult applying pharmacotherapy concepts to clinical cases. Not all students will struggle with this, but many do and simple study lists can be a great way to refresh or highlight some of the important points.
In an effort to provide an additional resource for learning antimicrobial spectrum basics, I have composed this article, which focuses on two of the most important pathogens in healthcare today: methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa.
MRSA Snapshot
MRSA is a catalase-positive Gram positive cocci and facultative anaerobe. In 2013 the U.S. Center for Disease Control and Prevention (CDC) released a report on antibiotic resistance threats (available here), which identified MRSA as a “serious” threat. Within this report it is noted that MRSA is a leading cause of healthcare-associated infections, with over 80,000 serious infections and over 11,000 deaths in the U.S. each year.
MRSA is such an important organism that the Infectious Diseases Society of America (IDSA) developed a clinical practice guideline (available here) to assist in managing MRSA infections. Whether working in the community or in the hospital, MRSA is an important pathogen.
Pseudomonas Snapshot
Pseudomonas aeruginosa is a non-fermenting Gram negative rod. Similar to MRSA, it made the 2013 CDC Threat Report, in which multidrug-resistant Pseudomonas aeruginosa was identified as a “serious” threat. Within the report it is identified that an estimated 51,000 healthcare-associated Pseudomonas aeruginosa infections occur in the U.S. each year, with nearly 7,000 of them being caused by multidrug-resistant strains.
Pseudomonas aeruginosa does not have it’s own clinical practice guideline, but it is an organism covered extensively in the organ system-focused IDSA guidelines. It is an incredibly important pathogen for healthcare personnel to be aware of and pharmacists should have a general awareness of which drugs can have activity against it.
List of Antibiotics that can Cover Pseudomonas and/or MRSA
The table below is sectioned into drug classes. One thing that can help when trying to list all the drugs that cover these organisms is to attempt to recall them using a structured approach, one class at a time.
Antibiotics without activity versus either of the pathogens have not been included.
NOTE: This general table is provided for study purposes only. Depending on factors such as infection type, patient-specific variables, and the presence of antibiotic resistance, some of the labeled options below may or may not be valid in clinical practice. For example, tigecycline can cover MRSA, but it distributes rapidly into the tissues upon IV administration, so tigecycline is a poor choice for MRSA bacteremia. In addition aminoglycosides and fluoroquinolones are indicated as a “no” for MRSA, but they may be an option as part of combination therapy.
Also, note that while lefamulin does cover MRSA, there is a lack of clinical data using it for this bug.
Hopefully this visual will be helpful for learning about which antibiotics can cover Pseudomonas aeruginosa and/or MRSA.
| Pseudomonas | MRSA | |
| Piperacilin-tazobactam |
+ |
– |
| Ceftazidime |
+ |
– |
| Ceftazidime-avibactam |
+ |
– |
| Cefepime |
+ |
– |
| Ceftaroline |
– |
+ |
| Ceftolozane-tazobactam |
+ |
– |
| Cefiderocol |
+ |
– |
| Imipenem-cilastatin |
+ |
– |
| Imipenem-cilastatin-relebactam |
+ |
– |
| Doripenem |
+ |
– |
| Meropenem |
+ |
– |
| Meropenem-vaborbactam |
+ |
– |
| Aztreonam |
+ |
– |
| Ciprofloxacin |
+ |
– |
| Levofloxacin |
+ |
– |
| Delafloxacin |
+ |
+ |
| Tetracycline |
– |
+ |
| Doxycycline |
– |
+ |
| Minocycline |
– |
+ |
| Tigecycline |
– |
+ |
| Omadacycline |
– |
+ |
| Eravacycline |
– |
+ |
| Sulfamethoxazole-trimethoprim |
– |
+ |
| Clindamycin |
– |
+ |
| Vancomycin |
– |
+ |
| Daptomycin |
– |
+ |
| Telavancin |
– |
+ |
| Oritavancin |
– |
+ |
| Dalbavancin |
– |
+ |
| Linezolid |
– |
+ |
| Tedizolid |
– |
+ |
| Dalfopristin-quinupristin |
– |
+ |
| Polymyxin B |
+ |
– |
| Polymyxin E (colistin) |
+ |
– |
| Gentamicin |
+ |
– |
| Tobramycin |
+ |
– |
| Amikacin |
+ |
– |
| Fosfomycin |
– |
+ |
|
+ |
+ |
|
| Nitrofurantoin |
– |
+ |
| + |
+ |
Recommended Readings & Resources
- Lui C, et al. Clinical practice guidelines by the infectious diseases society of america for the treatment of methicillin-resistant Staphylococcus aureus infections in adults and children. Clinical Infectious Diseases. 2011.
- Morita Y, et al. Responses of Pseudomonas aeruginosa to antimicrobials. Frontiers in Microbiology. 2013.
- Navon-Navezia S, et al. Update on Pseudomonas aeruginosa and Acinetobacter baumannii infections in the healthcare setting. Current Opinion Infectious Diseases. 2005.
- Sanford Guide antimicrobial spectra tables. Products available here.
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