Proteus mirabilis

A Microbial Biorealm page on the genus Proteus mirabilis

Classification

Higher order taxa

Domain; Phylum; Class; Order; family [Others may be used. Use NCBI link to find]

Species

NCBI: Taxonomy

Genus species

Genome structure

The genome sequence of Proteus mirabilis was completed in March 28, 2008 by Melanie M. Pearson identifying more than 3,658 coding sequences with 7 rRNA loci (Pearson etc. al, 2008). The genome’s total length is 4.063 Mb with a 28.8% GC content. P. mirabilis also carries a single plasmid with 36, 298 nucleotides. The plasmid itself does not contain any virulence genes but it may contain a bacteriocin and its immunity system Within the genome is a genomic island involved in pathogenicity that codes for a type III secretion system comprising 24 genes used to inject bacterial proteins into a host genome. This type III system appears to be incorporated through horizontal gene transfer and is noted for its relatively smaller G+C content compared with the rest of the genome (Pearson etc. al, 2008). The genome sequence encodes 17 different types of fimbriae as well as a 54 kb flagellar regulon. The flagella made by the strain all come from a single locus. This information is characterized for a specific uropathogenic strain of P. mirabilis, HI4320. It is the first completed sequence of the bacterium out of more than 75 known strains that were identified using one dimensional SDS PAGE of cellular proteins mostly from human origin (Holmes etc. al, 2008).

Current Research

Proteus mirabilis makes several different fimbriae that promote adhesion to mucosal surfaces. One of these fimbriae, called the mannose resistant Proteus- like fimbriae, has been highly present in patients associated with urinary tract infections (Xin etc. al, 1999). A mannose resistant Proteus- like gene (mrpH) present in the mrp operon of mrp fimbrae has been recently shown to be essential for functional adhesion of MR/P fimbrae(Xin etc. al, 1999). By using insertional mutagenesis, researchers noted that without the functional gene mrpH, there was less MR/P fimbriation. This information led to the conclusion that further research into the capabilities of the mrpH gene could lead to the production of a vaccine to render this gene ineffective. This would ultimately halt the ability of the Proteus mirabilis bacterium from attaching to mucosal surfaces, hindering infection (Xin etc. al, 1999).

Proteus mirabilis can be commonly present in healthy individuals as part of the normal mucosa. The bacterium becomes a significant problem mostly in individuals that have vulnerable immune systems and are in danger of nosocomial transmission, such as hospital patients (Farkosh etc. al, 2008). Current studies show that there are a number of antibiotics that were once effective against Proteus mirabilis that are now useless due to extended spectrum beta lactamases (ESBLs). These are enzymes passed through plasmids and are found in most of the Enterobacteriaceae. These plasmids were found within abscesses, blood, catheter tips, lung, peritoneal fluid, sputum, and throat culture (Farkosh etc. al, 2008). Detected in the 1980’s in Klebsiella and E. coli, these enzymes were found to hydrolyze antibiotic cephalosporin thus making it ineffective. The ESBL’s become highly dangerous when produced in copious amounts, conveying resistance to a large number of antibiotics used universally. The spread of these plasmids is primarily prevalent in healthcare facilities where patients have extended hospital stays, are using catheters, are within the ICU, have had recent surgery or are administered consistently with antibiotics.

References

Farkosh, S. Mary. “Extended-Spectrum beta-lactamase Producing Gram Negative Bacilli”. 2000. JHH HEIC. November 21, 2008. www.nosoweb.org/infectious_diseases/esbl.htm

Li, Xin; Johnson, E. David; and Mobley L.T Harry. “Requirement of MrpH for Mannose-Resistant Proteus-Like Fimbria-Mediated Hemagglutination by Proteus mirabilis”. American society of Microbiology. Infect Immun. 1999 June; 67(6): 2822–2833. [PubMed]

Pearson MM, Sebaihia M, Churcher C, Quail MA, Seshasayee AS, Luscombe NM, Abdellah Z, Arrosmith C, Atkin B, Chillingworth T, Hauser H, Jagels K, Moule S, Mungall K, Norbertczak H, Rabbinowitsch E, Walker D, Whithead S, Thomson NR, Rather PN, Parkhill J, Mobley HL. Complete genome sequence of uropathogenic Proteus mirabilis, a master of both adherence and motility. J Bacteriol. 2008 Jun;190(11):4027-37. Epub 2008 Mar 28.

Edited by Isioma Agboli, Michael Cao, Janice Love, and Fatima Morales