Related Experiment Video

Updated: Aug 16, 2026

A Murine Model of Group B Streptococcus Vaginal Colonization
10:19

A Murine Model of Group B Streptococcus Vaginal Colonization

Published on: November 16, 2016

14.6K

Cefazolin susceptibility of coagulase-negative staphylococci (CoNS) causing late-onset neonatal bacteraemia

I Marr1, K Swe2, A Henderson3

  • 1Infectious Disease Department, The Canberra Hospital, ACT, Australia.

The Journal of Antimicrobial Chemotherapy
|November 18, 2021
PubMed
Abstract

Insights

Cefazolin shows lower minimum inhibitory concentrations (MICs) against Coagulase-negative staphylococci (CoNS) in neonates compared to other beta-lactams. This suggests cefazolin may be a viable alternative for treating neonatal sepsis caused by these bacteria.

Area of Science:

  • Microbiology
  • Neonatal Medicine
  • Infectious Diseases

Background:

  • Coagulase-negative staphylococci (CoNS) bloodstream infections (bacteraemia) are a significant cause of morbidity in neonates.
  • Previous research indicates variability in beta-lactam antibiotic binding affinity to PBP2a, a protein produced by the mecA gene found in most CoNS.

Purpose of the Study:

  • To evaluate cefazolin's minimum inhibitory concentrations (MICs) for CoNS isolated from neonates in an Australian neonatal intensive care unit (NICU).
  • To correlate these MICs with the genotype and phenotype of the CoNS isolates.

Main Methods:

  • Significant blood isolates (2009-2017) were speciated and tested for susceptibility to cefazolin, cefoxitin, oxacillin, and flucloxacillin using broth microdilution.
  • Correlation with mecA gene presence and PBP2a expression was assessed.
  • Whole Genome Sequencing (WGS) was performed on a subset of Staphylococcus capitis isolates.

Main Results:

  • The study identified 99 CoNS isolates, predominantly Staphylococcus capitis (n=57) and Staphylococcus epidermidis (n=32).
  • Cefazolin exhibited lower MIC values (MIC90 = 16 mg/L) compared to cefoxitin, oxacillin, and flucloxacillin (all MIC90s ≥32 mg/L).
  • WGS revealed the presence of the globally established NRCS-A clone of S. capitis.

Conclusions:

  • CoNS isolates demonstrated notably lower MICs for cefazolin than for other tested agents.
  • Variations in cefazolin MICs may be attributed to PBP2a binding affinity or regulation of mecA expression.
  • The persistent presence of NRCS-A S. capitis strains warrants further investigation into potential common environmental sources and supports a randomized clinical trial comparing cefazolin and vancomycin for neonatal sepsis.

More Related Videos

A Neonatal Imaging Model of Gram-Negative Bacterial Sepsis08:46

A Neonatal Imaging Model of Gram-Negative Bacterial Sepsis

Published on: August 12, 2020

6.5K
Antibiotic Efficacy Testing in an Ex vivo Model of Pseudomonas aeruginosa and Staphylococcus aureus Biofilms in the Cystic Fibrosis Lung09:26

Antibiotic Efficacy Testing in an Ex vivo Model of Pseudomonas aeruginosa and Staphylococcus aureus Biofilms in the Cystic Fibrosis Lung

Published on: January 22, 2021

7.2K

Related Concept Videos

Staphylococcal Skin Infections01:29

Staphylococcal Skin Infections

Staphylococcus aureus is a Gram-positive coccus that resides harmlessly on the skin and mucous membranes of healthy individuals. When the skin barrier is breached, it can shift from a commensal to an opportunistic pathogen. This transition is facilitated by surface adhesins, such as clumping factor B and S. aureus surface protein G (SasG), which bind to structural proteins, including loricrin and cytokeratin, in the damaged epidermis. Protein A, another key factor, binds the Fc region of...
Mechanism of Antibiotic Resistance in MRSA01:25

Mechanism of Antibiotic Resistance in MRSA

Antibiotic resistance in bacteria arises when microorganisms evolve the ability to withstand drugs designed to kill them or inhibit their growth, rendering once-effective treatments useless. This phenomenon, driven by genetic change and selection under antibiotic exposure, poses a profound threat to modern medicine. Mechanisms include drug-inactivating enzymes (e.g., β-lactamases), efflux pumps that eject antibiotics, mutations altering antibiotic targets, decreased drug uptake, and acquisition...
Inhibitors of Bacterial DNA Synthesis01:28

Inhibitors of Bacterial DNA Synthesis

Bacterial pathogens depend on precise and efficient DNA replication to sustain infection. Two type II topoisomerases—DNA gyrase and topoisomerase IV—are critical to this process, as they resolve DNA supercoiling and unlink chromosomes during replication. Fluoroquinolones, synthetic derivatives of quinolones, exploit this mechanism by stabilizing the transient DNA–enzyme cleavage complex, preventing strand religation, and causing lethal double-strand breaks. These antibiotics are selectively...
Clinical Significance of Antibiotic Resistance01:25

Clinical Significance of Antibiotic Resistance

Methicillin-resistant Staphylococcus aureus (MRSA) presents a critical public health threat, arising from its capacity to resist β-lactam antibiotics due to acquisition of the mecA gene within the staphylococcal cassette chromosome mec (SCCmec). This gene encodes penicillin-binding protein 2a (PBP2a), which impairs binding efficacy of methicillin and other β-lactams. MRSA has evolved into distinct clonal lineages impacting humans and animals alike, reinforcing its significance within the One...