Spontaneous tibiotalar arthrodesis as a complication of acute tibial osteomyelitis due to Panton-Valentine leukocidin-producing Staphylococcus aureus: a case report

Coexistence of the blaZ gene and selected virulence determinants in multidrug-resistant Staphylococcus aureus: insights from three Nigerian tertiary hospitals

BACKGROUND AND PURPOSE

Infections caused by β-lactamase-producing strains of Staphylococcus aureus have become increasingly difficult to treat due to the expression of multiple virulence factors. This has heightened concerns about managing S. aureus-related infections. This study was conducted to characterize the blaZ gene and selected virulence determinants in β-lactam resistant S. aureus from human sources in three Nigerian tertiary hospitals.

MATERIALS AND METHODS

Three hundred and sixty samples were collected for the study. S. aureus was isolated and characterized following standard microbiological protocols and nuc gene amplification. Antibiotic susceptibility and minimum inhibitory concentration tests were performed using the disk diffusion method and E-tests, respectively. Biofilm formation and β-lactamase production were assessed using Congo red agar and nitrocefin kits, while the blaZ gene was examined using conventional PCR. Capsular polysaccharide genotyping, accessory gene regulator (agr) detection, Panton-valentine leucocidin (PVL), and PVL proteins were performed using PCR and Western blotting.

RESULTS

S. aureus was recovered from 145 samples, 50 (34.5%) of these isolates exhibited multidrug resistance, with MICs ranging from 0.125 to 1.00 µg/mL, and showed significant resistance to aminoglycosides, fluoroquinolones, and β-lactams. Of these, 31 strains produced β-lactamases, 30 of which carried the blaZ gene in combination with cap8 (80%) or cap5 (20%). Biofilm formation and PVL gene were observed in 85% of the 20 randomly selected blaZ-positive multidrug-resistant (MDR) strains. The agr2 allele was predominant, found in 70% of the selected MDR strains. No significant difference in the occurrence of the blaZ gene was found among the three clinical sources (p ≤ α0.05).

CONCLUSION

The co-occurrence of the blaZ gene with PVL, capsular polysaccharide genes, and agr alleles is associated with biofilm formation, indicating a high risk of β-lactam-resistant S. aureus infections. Our findings highlight the need for continuous molecular surveillance to enhance infection management, treatment options, and patient outcomes in the study locality. A limitation of this study is the random selection of MDR isolates, which may affect the comprehensiveness of the analyses.

Secretory proteins in the orchestration of microbial virulence: The curious case of Staphylococcus aureus

Microbial virulence showcases an excellent model for adaptive changes that enable an organism to survive and proliferate in a hostile environment and exploit host resources to its own benefit. In Staphylococcus aureus, an opportunistic pathogen of the human host, known for the diversity of the disease conditions it inflicts and the rapid evolution of antibiotic resistance, virulence is a consequence of having a highly plastic genome that is amenable to quick reprogramming and the ability to express a diverse arsenal of virulence factors. Virulence factors that are secreted to the host milieu effectively manipulate the host conditions to favor bacterial survival and growth. They assist in colonization, nutrient acquisition, immune evasion, and systemic spread. The structural and functional characteristics of the secreted virulence proteins have been shaped to assist S. aureus in thriving and disseminating effectively within the host environment and exploiting the host resources to its best benefit. With the aim of highlighting the importance of secreted virulence proteins in bacterial virulence, the present chapter provides a comprehensive account of the role of the major secreted proteins of S. aureus in orchestrating its virulence in the human host.

Panton-valentine leukocidin Staphylococcus aureus severe infection in an infant: a case report and a review of the literature

Background

Panton-Valentine leukocidin (PVL) is one of the major virulence factor of Staphylococcus aureus (SA) that might be associated with invasive life-threating infections. A prompt diagnosis and adequate treatment are essential in achieving the best outcome and avoiding serious sequelae. We describe a case of severe invasive PVL-SA infection in an infant. A literature review starting from 2010 was also performed in order to discuss clinical presentations, radiological findings, treatment and outcome.

Case presentation

This is a case of a 6-month-old boy who rapidly developed high fever and poor general condition. He was diagnosed as having multiple muscular abscesses, multiple foci of osteomyelitis and bloodstream infections caused by Panton-Valentine leukocidin Methicillin-resistant Staphylococcus aureus. He received intravenous antibiotics and surgical drainage of the abscess with progressive recovery.

Conclusion

Our report highlights the importance of improving awareness of this severe infection, as a prompt diagnosis and adequate manage is essential in order to save life and to prevent serious complications.

Panton-Valentine leukocidin osteomyelitis in children: a growing threat

Panton-Valentine leukocidin-producing Staphylococcus aureus osteomyelitis is associated with multiple complications including multiple abscesses, deep vein thrombosis and fulminant sepsis. This article reviews the literature concerning this emerging threat which is currently under-recognized.