''Morganella morganii'' is a species of Gram-negative bacteria.eMedicine
Morganella infections
/ref> It has a commensal relationship within the intestinal tracts of humans, mammals, and reptiles as normal flora. Although ''M. morganii'' has a wide distribution, it is considered an uncommon cause of community-acquired infection, and it is most often encountered in

postoperative Surgery ''cheirourgikē'' (composed of χείρ, "hand", and ἔργον, "work"), via la, chirurgiae, meaning "hand work". is a medical specialty that uses operative manual and instrumental techniques on a person to investigate or treat a pat ...

and other nosocomial infections, such as urinary tract infections.

Historical identification and systematics

''Morganella morganii'' was first described by a British bacteriologist H. de R. Morgan in 1906 as Morgan's bacillus. Morgan isolated the bacterium from stools of infants who were noted to have had "summer diarrhea". Later in 1919, Winslow'' et al.'' named Morgan's bacillus, ''Bacillus morganii''. In 1936, though, Rauss renamed ''B. morganii'' as ''Proteus morganii''. Fulton, in 1943, showed that ''B. columbensis'' and ''P. morganii'' were the same and defined the genus ''Morganella'', due to the DNA-DNA hybridization. ''M. morganii'' has two subspecies – ''M. m. morganii'' and ''M. m. columbensis''. However, in 1962, a review article by Ewing reported that ''M. columbensis'' had been re-identified as '' Escherichia coli'', thereby removing that organism from the genus ''Morganella''.

Microbiology

''Morganella morganii'' is facultatively anaerobic and oxidase-negative. Its colonies appear off-white and opaque in color, when grown on agar plates. ''M. morganii'' cells are straight rods, about 0.6–0.7

μm The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Unit ...

in diameter and 1.0–1.7 μm in length. This organism moves by way of peritrichous

flagella A flagellum (; ) is a hairlike appendage that protrudes from certain plant and animal sperm cells, and from a wide range of microorganisms to provide motility. Many protists with flagella are termed as flagellates. A microorganism may have f ...

, but some strains do not form flagella at . ''M. morganii'' can produce the enzyme

catalase Catalase is a common enzyme found in nearly all living organisms exposed to oxygen (such as bacteria, plants, and animals) which catalyzes the decomposition of hydrogen peroxide to water and oxygen. It is a very important enzyme in protecting t ...

, so it is able to convert hydrogen peroxide to water and oxygen. This is a common enzyme found in most living organisms. In addition, it is

indole test Indole is an aromatic Heterocyclic compound, heterocyclic organic compound with the formula Carbon, C8Hydrogen, H7Nitrogen, N. It has a bicyclic structure, consisting of a six-membered benzene ring fused to a five-membered pyrrole ring. Indole ...

-positive, meaning that this organism can split tryptophan to indole,

pyruvate Pyruvic acid (CH3COCOOH) is the simplest of the alpha-keto acids, with a carboxylic acid and a ketone functional group. Pyruvate, the conjugate base, CH3COCOO−, is an intermediate in several metabolic pathways throughout the cell. Pyruvic aci ...

, and ammonia. Methyl red tests positive in ''M. morganii'', an indicator dye that turns red due to the bacterium's acid production during

fermentation Fermentation is a metabolic process that produces chemical changes in organic substrates through the action of enzymes. In biochemistry, it is narrowly defined as the extraction of energy from carbohydrates in the absence of oxygen. In food ...

. Although a rare human pathogen, ''M. morganii'' has been reported as a cause of urinary tract infections, nosocomial surgical wound infections, peritonitis, central nervous system infection, endophthalmitis, pneumonia, chorioamnionitis, neonatal sepsis,

pyomyositis Pyomyositis is a bacterial infection of the skeletal muscles which results in an abscess. Pyomyositis is most common in tropical areas but can also occur in temperate zones. Diagnosis Diagnosis is done via the following manner: * Pus discharge cul ...

, necrotizing fasciitis, and

arthritis Arthritis is a term often used to mean any disorder that affects joints. Symptoms generally include joint pain and stiffness. Other symptoms may include redness, warmth, swelling, and decreased range of motion of the affected joints. In som ...

. Numerous cases of nosocomial infection have been described, usually as postsurgical wound infections or urinary tract infections. Patients in whom

bacteremia Bloodstream infections (BSIs), which include bacteremias when the infections are bacterial and fungemias when the infections are fungal, are infections present in the blood. Blood is normally a sterile environment, so the detection of microb ...

develops are typically immunocompromised, diabetic, or elderly, or have at least one serious underlying disease.

Role of bacteria

''M. morganii'' consists of two species: ''M. morganii'' and ''M. sibonii''. ''M. morganii'' has been regarded as a normally harmless opportunistic pathogen, but some strains carry " antibiotic-resistant

plasmid A plasmid is a small, extrachromosomal DNA molecule within a cell that is physically separated from chromosomal DNA and can replicate independently. They are most commonly found as small circular, double-stranded DNA molecules in bacteria; how ...

s" and have been associated with nosocomial outbreaks of infections. Several reports indicate ''M. morganii'' causes sepsis, ecthyma, endophthalmitis, and chorioamnionitis, and more commonly urinary tract infections, soft tissue infections, septic arthritis,

meningitis Meningitis is acute or chronic inflammation of the protective membranes covering the brain and spinal cord, collectively called the meninges. The most common symptoms are fever, headache, and neck stiffness. Other symptoms include confusion or ...

, and

, in the latter 2 cases with frequent fatal consequences. In a rare case published in 2003, a patient presented with bilateral necrosis of both upper and lower eyelids. Upon microbial analysis, the areas were shown to have heavy growth of ''M. morganii''.

Treatment and antibiotic resistance

Treatment of ''M. morganii'' infections may include: * Ticarcillin * Piperacillin * Ciprofloxacin * Third-generation and fourth-generation cephalosporins A study conducted at the University Hospital at Heraklion, Crete, Greece, showed a 92% success rate in the use of these

antibiotic An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention of ...

s. However, some ''M. morganii'' strains are resistant to

penicillin Penicillins (P, PCN or PEN) are a group of β-lactam antibiotics originally obtained from ''Penicillium'' moulds, principally '' P. chrysogenum'' and '' P. rubens''. Most penicillins in clinical use are synthesised by P. chrysogenum using ...

, ampicillin/sulbactam, oxacillin, first-generation and second-generation cephalosporins, macrolides, lincosamides, fosfomycin, colistin, and polymyxin B. The emergence of highly resistant strains of ''M. morganii'' have been associated with use of third-generation cephalosporins. Polymicrobial infections are most abundantly caused by this microbe which additionally damages the skin, soft tissues, and

urogenital tract The genitourinary system, or urogenital system, are the organs of the reproductive system and the urinary system. These are grouped together because of their proximity to each other, their common embryological origin and the use of common pathwa ...

; these can be cured through use of the aforementioned antibiotics.

References

External links