Pantoea: Introduction, Classification Morphology, Pathogenicity, Lab Diagnosis, Treatment, and Prevention

Introduction

Pantoea is a genus of gram-negative bacteria that belong to the family Enterobacteriaceae. These bacteria are commonly found in soil, water, and plant surfaces, and some species are known to be associated with plants, animals, and humans as opportunistic pathogens.

There are several species within this genus, including Pantoea agglomerans, P. dispersa, P. ananatis, and P. stewartii. P. agglomerans is one of the most common species found in various environments and is known to be involved in plant growth promotion, biocontrol of plant pathogens, and degradation of organic pollutants. However, it can also cause opportunistic infections in humans, particularly in immunocompromised individuals.

Classification of Pantoea

The scientific classification of Pantoea is as follows:

  • Domain: Bacteria
  • Phylum: Proteobacteria
  • Class: Gammaproteobacteria
  • Order: Enterobacterales
  • Family: Enterobacteriaceae
  • Genus: Pantoea
  • Species: P. agglomerans

There are currently more than 20 recognized species within the Pantoea genus, each with their own unique characteristics and properties. Some of the most well-known species include P. agglomerans, P. ananatis, P. dispersa, and P. stewartii.

Morphology

Pantoea bacteria are gram-negative, rod-shaped bacteria. They are typically 1-2 micrometers in length and 0.5-1 micrometer in width. Like other gram-negative bacteria, they have an outer membrane and a thinner peptidoglycan layer in their cell wall.

Pantoea colonies are typically smooth, shiny, and circular in shape, with a slightly raised appearance. They are usually white, cream or yellow in color and may exhibit pigmentation under certain growth conditions.

Under a microscope, Pantoea cells appear as rods that are often found singly but can also form short chains or clusters. Some species of Pantoea can also produce polar flagella or be motile through twitching motility, which is the movement of the bacterial cell by extending and retracting pili.

Pantoea in Gram Staining of Culture Microscopy at Magnification of 4000X
Fig. Pantoea in Gram Staining of Culture Microscopy at Magnification of 4000X

Pathogenicity of Pantoea

Pantoea bacteria are generally considered to be opportunistic pathogens, meaning that they can cause disease in certain circumstances, particularly in individuals with weakened immune systems or in patients with pre-existing medical conditions.

Some species of this bacteria are known to be associated with infections in humans, such as urinary tract infections, wound infections, and bloodstream infections. P. agglomerans is perhaps the most well-known pathogenic species, and has been linked to infections in both healthy and immunocompromised individuals, particularly in hospital settings.

In addition to causing infections in humans, some species of Pantoea can also be plant pathogens, causing diseases in crops and other plants. For example, P. stewartii is a pathogen of maize plants, causing Stewart’s wilt disease, which can result in significant crop losses.

Lab Diagnosis of Pantoea

The laboratory diagnosis of Pantoea involves a combination of microbiological and molecular techniques.

Isolation and identification of Pantoea can be achieved using culture-based methods, such as streaking a sample onto a selective agar medium, such as MacConkey agar, and incubating at an appropriate temperature (typically 35-37°C) for 24-48 hours. The colonies of Pantoea are typically smooth, shiny, and circular in shape, with a slightly raised appearance. They are usually white, cream or yellow in color and may exhibit pigmentation under certain growth conditions.

Pantoea lactose fermenting colonies on CLED agar
Fig. Pantoea lactose fermenting (LF) colonies on CLED agar

Further identification can be done using biochemical tests to determine the characteristics of the isolated bacteria. Some commonly used tests include oxidase, catalase, indole production, and the ability to ferment various sugars.

Molecular methods, such as polymerase chain reaction (PCR), can also be used to identify Pantoea at the species level. PCR amplifies specific DNA sequences that are unique to different species of Pantoea, allowing for more rapid and accurate identification.

In cases where Pantoea is suspected to be the causative agent of infection, additional tests may be performed to determine antibiotic susceptibility, which can guide appropriate treatment options.

Pantoea species in tryptone soy broth mount microscopy at a magnification of 1600X
Fig. Pantoea species in tryptone soy broth mount microscopy at a magnification of 1600X

Treatment and Prevention

The treatment of Pantoea infections depends on the species causing the infection, the severity of the infection, and the overall health of the patient.

In general, Pantoea infections are treated with antibiotics, such as fluoroquinolones, aminoglycosides, cephalosporins, and carbapenems. The choice of antibiotic depends on the antibiotic susceptibility of the specific strain of Pantoea causing the infection. Antimicrobial susceptibility testing should be performed on the isolate to guide appropriate antibiotic therapy.

It is worth noting that some species of this genus have been shown to be resistant to certain antibiotics, and emerging antibiotic resistance is a growing concern. Therefore, it is important to use antibiotics judiciously and to follow appropriate antibiotic stewardship practices.

In addition to antibiotic therapy, supportive care may also be necessary, such as fluid and electrolyte management, wound care, and management of any underlying medical conditions.

Prevention measures, such as good hand hygiene and infection control practices, can also help to reduce the risk of Pantoea infections, particularly in hospital settings where opportunistic infections are more common.

Keynotes

  • It is important to note that taxonomic classification is an ongoing process, and as new research is conducted on Pantoea and other bacteria, the classification may be subject to revision or updates.
  • It is worth noting, however, that not all species of this genus are pathogenic. Some species have been shown to have beneficial properties, such as promoting plant growth, producing enzymes that can degrade pollutants, and having probiotic effects on the gut microbiome. The pathogenicity of this bacteria depends on the species and the context in which they are found.

Leave a Comment