Panton–Valentine leukocidin

Panton–Valentine leukocidin (PVL) is a cytotoxin—one of the β-pore-forming toxins associated with Staphylococcus aureus. The presence of PVL is a distinguishing feature of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) strains, though it can also be found in methicillin-susceptible Staphylococcus aureus (MSSA) strains. PVL is linked to severe skin and soft tissue infections as well as necrotizing pneumonia. It is named after Sir Philip Noel Panton and Francis Valentine, who first described it in association with a soft tissue infection in 1932.

Structure and Mechanism

PVL is a bicomponent toxin, consisting of two separate proteins, LukS-PV and LukF-PV, which act together to form pores in the membranes of infected cells. This action leads to cell lysis and death. The genes encoding these proteins, lukS-PV and lukF-PV, are located on a bacteriophage integrated into the Staphylococcus aureus genome, which suggests that PVL's presence in Staphylococcus aureus strains may be due to horizontal gene transfer.

Clinical Significance

PVL-producing Staphylococcus aureus strains are particularly virulent and have been associated with severe clinical outcomes. Infections can range from mild skin infections, such as boils and abscesses, to more severe conditions like necrotizing fasciitis and necrotizing pneumonia. The latter is a life-threatening condition characterized by rapid destruction of lung tissue, high fever, and breathing difficulties. The presence of PVL is considered a risk factor for severe disease, especially in the context of pneumonia.

Diagnosis and Treatment

Diagnosis of PVL-producing Staphylococcus aureus infection is based on the detection of the lukS-PV and lukF-PV genes by polymerase chain reaction (PCR) from clinical specimens. Treatment involves the use of appropriate antibiotics, though the choice of antibiotic may be complicated by the resistance profile of the Staphylococcus aureus strain. In cases of severe infection, supportive care in an intensive care unit (ICU) may be necessary. Surgical intervention may be required for cases involving deep-seated infections or necrotizing fasciitis.

Prevention

Preventive measures against PVL-producing Staphylococcus aureus infections include good hygiene practices, such as regular hand washing and proper wound care. In healthcare settings, adherence to infection control guidelines is crucial to prevent the spread of these bacteria.

Epidemiology

The prevalence of PVL-producing Staphylococcus aureus varies geographically, with higher rates reported in some community settings and among certain populations, such as athletes, military recruits, and children. The global spread of CA-MRSA strains carrying the PVL genes has raised concerns about the potential for increased virulence and transmissibility of these strains.

See Also

• Methicillin-resistant Staphylococcus aureus (MRSA)
• Staphylococcus aureus
• Necrotizing fasciitis
• Necrotizing pneumonia

External Links

• CDC MRSA Information
• World Health Organization (WHO)