What is the best antibiotic for a staph infection?

October 9, 2025 •

3 min read

In 2017, there were an estimated 119,247 Staphylococcus aureus bloodstream infections and 19,832 associated deaths in the United States. Understanding what is the best antibiotic for a staph infection is critical, as the answer depends heavily on the specific bacterial strain and infection severity.

Quick Summary

The best antibiotic for a staph infection is not a single drug but is determined by whether the strain is methicillin-resistant (MRSA) or susceptible (MSSA), the infection's location, and patient-specific factors. Professional diagnosis is essential.

Key Points

No Single 'Best' Antibiotic: The most effective antibiotic is determined by the specific strain of staph and the infection's severity, requiring a professional diagnosis.
MSSA vs. MRSA is Key: The primary factor is whether the staph is methicillin-susceptible (MSSA) or methicillin-resistant (MRSA), as they require different classes of antibiotics.
Common MSSA Treatments: For non-resistant staph, beta-lactam antibiotics like cephalexin and dicloxacillin are often the first choice.
Standard MRSA Treatments: For serious MRSA infections, IV vancomycin is a primary treatment, while oral drugs like doxycycline or Bactrim are used for community-acquired cases.
Drainage is Crucial: For skin abscesses, incision and drainage by a doctor is a key part of treatment and may sometimes be sufficient without antibiotics.
Resistance is a Serious Threat: Incorrect antibiotic use contributes to resistance; always complete the prescribed course and do not self-medicate.
Professional Diagnosis is Essential: Lab tests are needed to identify the bacteria and its antibiotic sensitivities to ensure effective treatment.

Understanding Staph Infections

Staphylococcus aureus, or "staph," is a common bacterium found on the skin and in the nasal passages of about one-third of the population. While often harmless, it can cause infections if it enters the body through a cut or wound. These infections range from minor skin issues to life-threatening conditions like pneumonia and bloodstream infections. A crucial distinction for treatment is between Methicillin-susceptible S. aureus (MSSA) and Methicillin-resistant S. aureus (MRSA). MRSA is a strain that has developed resistance to several antibiotics, making it more difficult to treat.

How the 'Best' Antibiotic is Determined

There is no single "best" antibiotic for all staph infections. A healthcare provider selects the most appropriate medication based on several critical factors:

Lab Culture and Susceptibility Testing: A sample from the infection site is cultured to identify the specific bacteria and test which antibiotics are effective against it. This is the most reliable way to guide therapy.
Type of Staph (MSSA vs. MRSA): This is the primary determinant. MSSA can be treated with a class of antibiotics called beta-lactams, which are often preferred for their effectiveness, whereas MRSA requires different agents.
Severity and Location of Infection: A simple skin boil may only require drainage or a topical antibiotic, while a severe bloodstream infection (bacteremia) or bone infection (osteomyelitis) requires powerful intravenous (IV) antibiotics.
Patient Factors: A doctor will consider a patient's allergies (especially to penicillin), age, kidney function, and other medical conditions when prescribing an antibiotic.

Common Antibiotics for MSSA Infections

For staph infections susceptible to methicillin (MSSA), beta-lactam antibiotics are commonly used. These include penicillinase-resistant penicillins like dicloxacillin (oral), nafcillin (IV), and oxacillin (IV). First-generation cephalosporins, such as cephalexin (oral) and cefazolin (IV), are also frequent choices, particularly for skin infections.

Tackling Resistant Strains: Antibiotics for MRSA

Treating MRSA requires different antibiotics due to its resistance. Options vary based on infection severity and whether it is community- or hospital-acquired. Vancomycin is a primary IV treatment for serious MRSA infections in hospitalized patients. Oral antibiotics like trimethoprim-sulfamethoxazole, doxycycline, and clindamycin are used for less severe community-acquired MRSA skin infections. Newer antibiotics such as linezolid, daptomycin, and ceftaroline may be considered in complex cases.

Comparison of Common Staph Antibiotics


Antibiotic	Target (Common Use)	Route	Key Considerations
Cephalexin (Keflex)	MSSA	Oral	A first-line choice for non-severe MSSA skin infections. Does not cover MRSA.
Dicloxacillin	MSSA	Oral	A penicillinase-resistant penicillin effective for MSSA skin infections.
Vancomycin	MRSA	IV	The standard for serious, hospitalized MRSA infections. Requires monitoring to avoid kidney damage.
Doxycycline	MRSA (Community)	Oral	A good oral option for community-acquired MRSA. Can cause sensitivity to sunlight.
Clindamycin	MSSA & MRSA	Oral / IV	Used for both types, but resistance in MRSA is a growing concern. Associated with C. difficile diarrhea.

The Critical Role of Medical Professionals

Self-treating staph infections with incorrect antibiotics is dangerous and contributes to antibiotic resistance. The CDC highlights antibiotic resistance as a significant threat. For skin abscesses, incision and drainage by a doctor is often the primary treatment and can be sufficient for simple cases. Always complete the full antibiotic course as prescribed.

Authoritative Link: Learn more about antibiotic resistance from the CDC

Conclusion

Ultimately, the question of what is the best antibiotic for a staph infection can only be answered by a healthcare professional after proper diagnosis and testing. The appropriate treatment depends on the specific staph strain (MSSA or MRSA), the infection's characteristics, and the individual patient's health factors. Seeking timely medical advice is crucial for effective treatment and to help combat antibiotic resistance.

Frequently Asked Questions

MRSA (Methicillin-Resistant Staphylococcus aureus) is a specific type of staph bacteria that is resistant to several common antibiotics, including methicillin. A staph infection can be caused by MRSA or by methicillin-susceptible Staphylococcus aureus (MSSA), which is treatable with a wider range of antibiotics.

No. You should never use leftover antibiotics. The antibiotic may not be effective for your specific infection, and incorrect use contributes to the dangerous rise of antibiotic-resistant bacteria. Always see a doctor for a proper diagnosis and prescription.

For outpatient or community-acquired MRSA skin infections, first-line oral antibiotic options often include trimethoprim-sulfamethoxazole (Bactrim), doxycycline, and clindamycin.

No, cephalexin (Keflex) does not cover MRSA. It is a first-generation cephalosporin that is effective for skin infections caused by MSSA (methicillin-susceptible Staphylococcus aureus), but not resistant strains.

Most people who take the correct oral antibiotics for a staph infection begin to feel better within two to three days. However, it is critical to complete the entire prescribed course, which often lasts 7 to 10 days, to fully eradicate the bacteria.

The primary treatment for a staph abscess or boil is incision and drainage performed by a healthcare professional. For simple, drained abscesses, antibiotics may not always be necessary.

If left untreated or treated incorrectly, a staph infection can worsen and spread, potentially leading to severe complications like bloodstream infections (sepsis), pneumonia, or bone infections. Untreated MRSA can be fatal.