What Flucloxacillin Treats

Flucloxacillin belongs to the penicillin family of antibiotics and is specifically engineered to resist the action of bacterial enzymes known as beta lactamases. These enzymes often render ordinary penicillins ineffective, particularly against Staphylococcus aureus. By remaining stable in the presence of these enzymes, flucloxacillin provides a targeted treatment against penicillinase producing bacteria.

Skin and Soft Tissue Infections
The most common use of flucloxacillin is for infections of the skin and soft tissues. It is the preferred choice for impetigo, where broken skin becomes crusted and inflamed, as well as for boils and abscesses that require not only surgical drainage but also systemic antibiotic cover. Flucloxacillin effectively treats cellulitis, a deeper bacterial invasion characterised by redness, swelling and warmth of the affected area, and erysipelas, which typically presents with raised, sharply demarcated patches of inflamed skin. In cases of infected eczema or wounds where staphylococcal overgrowth is suspected, flucloxacillin helps to clear the infection and allows the skin to heal.

Deeper and Systemic Staphylococcal Infections
Beyond superficial infections, flucloxacillin is indicated for more serious staphylococcal diseases. In osteomyelitis, where bacteria invade bone tissue, prolonged courses of flucloxacillin can eradicate the infection when combined with surgical intervention if needed. Septic arthritis, an infection of the joint space causing severe pain and swelling, also responds well to this antibiotic under hospital supervision. When Staphylococcus aureus enters the bloodstream and causes septicaemia, flucloxacillin is a mainstay of treatment unless methicillin resistant strains are present. For endocarditis prophylaxis or therapy in patients with staphylococcal involvement of the heart valves, flucloxacillin can be used, often alongside other agents as guided by specialist protocols.

Limitations and Resistance Considerations
Flucloxacillin is ineffective against methicillin resistant Staphylococcus aureus and offers no reliable activity against gram negative bacteria or anaerobic organisms. It must be prescribed only when the infecting organism is known or strongly suspected to be penicillinase producing staphylococci. Adherence to the prescribed dose and duration is crucial; incomplete courses risk relapse of infection and contribute to antibiotic resistance. Patients should report any signs of allergy such as rash or breathing difficulties, which require immediate medical attention.

Conclusion
Flucloxacillin remains a first choice antibiotic for a range of staphylococcal infections, from common skin conditions to more severe bone, joint and bloodstream infections. Its resistance to beta lactamase enzymes ensures reliable activity against penicillinase producing Staphylococcus aureus. Careful use under medical supervision, with appropriate dosing and duration, helps to clear infections effectively and minimise the risk of resistance.