Related Experiment Video

Updated: Aug 15, 2026

Characterization of a Pathogenic Escherichia coli Strain Derived from Oreochromis spp. Farms Using Whole-Genome Sequencing
09:44

Characterization of a Pathogenic Escherichia coli Strain Derived from Oreochromis spp. Farms Using Whole-Genome Sequencing

Published on: December 23, 2022

SHV-type extended-spectrum beta-lactamase production is associated with Reduced cefepime susceptibility in

Dóra Szabó1, Robert A Bonomo, Fernanda Silveira

  • 1Division of Infectious Diseases, University of Pittsburgh, Pittsburgh, PA 15213, USA.

Journal of Clinical Microbiology
|October 7, 2005
PubMed

Insights

Cefepime effectiveness against Enterobacter cloacae is challenged by extended-spectrum beta-lactamases (ESBLs). Many ESBL-producing strains show high cefepime resistance, potentially misclassified as susceptible by current guidelines.

Area of Science:

  • Microbiology
  • Infectious Diseases
  • Pharmacology

Background:

  • Cefepime is a fourth-generation cephalosporin antibiotic.
  • Enterobacter cloacae is an opportunistic pathogen.
  • Extended-spectrum beta-lactamases (ESBLs) confer resistance to beta-lactam antibiotics.

Purpose of the Study:

  • To investigate the prevalence and characteristics of ESBL production in Enterobacter cloacae bloodstream isolates.
  • To evaluate the in vitro susceptibility of these isolates to cefepime.
  • To assess the reliability of phenotypic ESBL detection methods.

Main Methods:

  • PCR amplification of bla genes to detect ESBLs.
  • Determination of minimum inhibitory concentrations (MICs) for cefepime.
  • Comparison of cefepime MICs with Clinical and Laboratory Standards Institute (CLSI) breakpoints.

Main Results:

  • One-third of E. cloacae isolates produced SHV-type ESBLs, often alongside AmpC hyperproduction and TEM-1.
  • ESBL-producing strains exhibited significantly higher cefepime MICs (MIC(90) = 64 µg/ml) compared to non-producers (MIC(90) = 0.5 µg/ml).
  • Two-thirds of ESBL-producing isolates were misclassified as susceptible to cefepime using current CLSI breakpoints.

Conclusions:

  • The emergence of ESBLs in E. cloacae compromises cefepime efficacy.
  • Current cefepime breakpoints may overestimate susceptibility in ESBL-producing strains.
  • Reevaluation of cefepime pharmacokinetic/pharmacodynamic (PK/PD) parameters and clinical breakpoints for E. cloacae is warranted.

More Related Videos

Isolation and Identification of Waterborne Antibiotic-Resistant Bacteria and Molecular Characterization of their Antibiotic Resistance Genes08:58

Isolation and Identification of Waterborne Antibiotic-Resistant Bacteria and Molecular Characterization of their Antibiotic Resistance Genes

Published on: March 3, 2023

Related Concept Videos

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...
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...
Development of Antibiotic Resistance01:30

Development of Antibiotic Resistance

Antibiotic resistance is a major public health concern that arises when bacteria evolve mechanisms to withstand the effects of antibiotic treatments. This resistance can be intrinsic, acquired through genetic mutations, or transferred between bacteria via horizontal gene transfer. The development of antibiotic resistance poses significant challenges in treating bacterial infections and necessitates ongoing research to develop new therapeutic strategies.Intrinsic resistance occurs when bacterial...
Bacterial Gastroenteritis01:18

Bacterial Gastroenteritis

Bacterial gastroenteritis, characterized by diarrhea, abdominal cramps, and vomiting, is often caused by ingestion of contaminated food or water and is frequently associated with pathogenic Escherichia coli strains. These microbes exploit two principal mechanisms to inflict disease.Shiga toxin–producing E. coli, also referred to as STEC—notably O157:H7—release Shiga toxins that target ribosomes, blocking protein synthesis. The B subunit of the toxin binds the host glycolipid receptor...
Inhibitors of Gram-positive Cell Wall Synthesis01:23

Inhibitors of Gram-positive Cell Wall Synthesis

Bacterial cell walls are typically rigid structures composed mainly of peptidoglycan, a mesh-like polymer that provides mechanical strength and maintains cell shape. The synthesis of peptidoglycan is a crucial process in bacterial growth and serves as a primary target for many antibiotics.Mechanism of Action of Beta-Lactam AntibioticsBeta-lactam antibiotics, such as penicillin, inhibit peptidoglycan synthesis in actively growing cells. These antibiotics share a characteristic four-membered...
Pharmaceutical Alternatives: Stability-Related Therapeutic Nonequivalence01:22

Pharmaceutical Alternatives: Stability-Related Therapeutic Nonequivalence

Generic intravenous (IV) drugs are considered bioequivalent to their branded counterparts due to their 100% bioavailability upon administration. However, variations in stability among different drug products can significantly influence their therapeutic performance, even if they are pharmaceutically equivalent.Cefuroxime, a prophylactic antimicrobial, is often used as a single-dose IV injection for patients undergoing coronary artery bypass grafting surgery. A 3 g dose typically provides...