MICROBIOLOGY
Enhanced in-house MRSA testing algorithm for detecting PVL toxins
Staphylococcus aureus is one of a number of pathogens with increased abilities to evade the effects of antimicrobial agents, with MRSA continuing to evolve. New technology is now allowing quicker identification of infection-causing pathogens, allowing earlier treatment and adoption of other measures to limit spread, explains Camila Onyekwere.
Multidrug resistance, recognised as one of the foremost global health challenges, stems largely from the overuse and misuse of antimicrobial agents. Among the most pressing concerns within this realm are ESKAPE pathogens, representing a group of bacteria resilient to multiple drugs and capable of causing severe infections. ESKAPE, an acronym encompassing both Gram-positive and Gram-negative species, comprises Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter.1
These
pathogens are notorious for their ability to evade the effects of antimicrobial agents,
posing significant threats to public health due to their high resistance to multiple antibiotics.
Impact of multidrug resistance The rising prevalence of antibiotic- resistant organisms, particularly those linked to nosocomial infections, greatly strains healthcare systems worldwide. This strain manifests in various ways, including elevated mortality and morbidity rates, heightened treatment costs, diagnostic challenges, and a growing scepticism toward conventional medical interventions. Consequently, urgent action is warranted to bolster antibiotic stewardship efforts and devise effective
A Grape-like clusters B
Golden yellow colony on an enriched media plate
strategies to combat antimicrobial resistance.1
ESKAPE pathogens, known for
their resilience, can evade the biocidal effects of antimicrobial agents through genetic mutations and the acquisition of mobile genetic elements. They represent new challenges in disease development, resistance to treatment, and transmission. These pathogens have frequently shown resistance to a range of antimicrobial agents, including oxazolidinones, lipopeptides, macrolides, fluoroquinolones, tetracyclines, β-lactams, and even carbapenems, which are considered last-resort treatments,2 highlighting a significant public health concern.
Background to Staphylococcus aureus
Fig 1. Microscopic and phenotypic appearance of Staphylococcus aureus. a) Grape-like (circular) clusters. b) Gold colonies displayed on enriched culture media.3,5,6
WWW.PATHOLOGYINPRACTICE.COM JUNE 2024
This clustering arises from the incomplete separation of daughter cells following division in three alternating perpendicular planes.4 The aureus species component of its name is derived from its golden
Staphylococcus aureus is a clinically significant bacterium responsible for a spectrum of human infections, ranging from mild to severe, including tissue infections and sepsis. This organism is recognised by its grape-like cluster arrangement under a microscope, S. aureus earns its name from the Greek ‘stafle’, meaning wine grape, due to its clustered appearance on Gram staining (Fig 1a).3
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