Related Experiment Video
Updated: Jul 18, 2026
Harvesting Venom Toxins from Assassin Bugs and Other Heteropteran Insects
Published on: April 21, 2018
[Proteus penneri]
Rafael Cantón1, M Paz Sánchez-Moreno, María Isabel Morosini Reilly
1Servicio de Microbiología, Hospital Universitario Ramón y Cajal, Madrid, España. rcanton.hrc@salud.madrid.org
Abstract:
Proteus penneri, formerly P. vulgaris biogroup 1, was recognized as a new species in 1982. This species is associated with clinical processes similar to those involving P. mirabilis and P. vulgaris and expresses similar pathogenic determinants. In clinical samples, P. penneri is mainly isolated from urine (50%), wound and soft tissue exudates (25%), and blood cultures (15%), mostly of nosocomial origin. Although P. penneri is easy to identify, it can be misidentified as P. vulgaris by automatic systems that do not include the indol test result in the identification process. This species has a characteristic susceptibility profile, essentially due to the production of the chromosomal inducible beta-lactamase HugA, which presents a high homology (86%) with CumA from P. vulgaris. HugA is inhibited by clavulanic acid and determines resistance to aminopenicillins and first- and second-generation cephalosporins, including cefuroxime, but does not affect cephamycins or carbapenems, and is inhibited by clavulanic acid. HugA is derepressed due to mutational processes in gene regulators, affecting the activity of cefotaxime and, to a much lesser extent, that of ceftazidime and aztreonam. This phenotype resembles the production of an extended spectrum beta-lactamase. Like other Proteus species, P. penneri is resistant to tetracyclines and should be considered resistant to nitrofurantoin.
Insights
Proteus penneri, a nosocomial pathogen, is often misidentified and exhibits unique antibiotic resistance due to the HugA beta-lactamase. Understanding its resistance profile is crucial for effective clinical treatment.
Area of Science:
- Microbiology
- Clinical Infectious Diseases
- Bacterial Pathogenesis
Context:
- Proteus penneri, previously P. vulgaris biogroup 1, is a distinct species identified in 1982.
- This bacterium shares clinical similarities and pathogenic factors with Proteus mirabilis and Proteus vulgaris.
- Predominantly isolated from nosocomial infections, particularly urine (50%), wound exudates (25%), and blood cultures (15%).
Purpose:
- To highlight the diagnostic challenges in identifying Proteus penneri, especially its misidentification as P. vulgaris by automated systems lacking the indole test.
- To characterize the unique antimicrobial susceptibility profile of P. penneri, focusing on the role of the HugA beta-lactamase.
- To elucidate the genetic basis and phenotypic expression of HugA-mediated resistance.
Summary:
- Proteus penneri is a nosocomial pathogen frequently isolated from urine and wound infections.
- It can be misidentified as P. vulgaris due to reliance on automated systems that omit the indole test.
- A key feature is the inducible beta-lactamase, HugA, conferring resistance to aminopenicillins and early-generation cephalosporins, with altered activity against later-generation agents.
- HugA's activity is similar to extended-spectrum beta-lactamases (ESBLs) and is inhibited by clavulanic acid.
Impact:
- Accurate identification of P. penneri is essential to avoid misdiagnosis and ensure appropriate antibiotic selection.
- Understanding the HugA beta-lactamase mechanism aids in predicting resistance patterns and managing infections caused by this species.
- The study emphasizes the need for specific diagnostic tests, like the indole test, for reliable Proteus species differentiation in clinical settings.
Related Concept Videos
01:15Diversity of Protists I
02:40Epiphytes, Parasites, and Carnivores