Morganella Morganii Infection: Pathogenesis, Symptoms, and Management

Introduction

Morganella morganii is an emerging superbug that can cause many nosocomial and bloodstream infections. The microbial pathogen belongs to the tribe Proteeae. The genera Proteus and Providencia also comprise the tribe Proteeae. Morganella morganii is resistant to Cephalosporins and Penicillins because of the presence of blaAmpC, which is encoded in its chromosomal DNA. Antibiotic treatment with Quinolones, Aminoglycosides, Cotrimoxazole, or Carbapenems is advised. However, Morganella morganii has got an increased potential to acquire resistance against other antibiotics also. Despite its emerging potential to cause infections, very little literature is available. Therefore, this article unravels the virulence and potency of this superbug for causing infections.

Why Is Morganella Morganii Labeled As an Emerging Superbug?

• Because of the occurrence of blaAmpC and other virulence factors that are deeply encoded in the bacterial chromosomal DNA (deoxyribonucleic acid), Morganella morganii is labeled as an emerging superbug. It is resistant to Cephalosporins and Penicillins.

• It has the ability to cause invasive diseases in children and adults. It can enter the bloodstream and cause blood-borne infections.

• It has got the potential to acquire resistant strains against other antibiotics.

What Is the Microbiology of Morganella Morganii?

• Morganella is a Gram-negative bacterium. It is rod-shaped. It frequently occurs in the environment and lives in a commensal relationship as normal flora in the intestinal tracts of human beings, reptiles, and mammals. It belongs to the tribe Proteeae. The genus belongs to the family Enterobacteriaceae.

• The bacterium was first discovered by the researcher Morgan in 1960, who discovered a non-lactose fermenting microbial pathogen in pediatric patients suffering from summer infantile diarrhea. Later, this bacterium was identified as Morganella and became known as Morgan’s bacillus.

• They are mobile, non-lactose fermenting bacilli rods with a Gram-negative cell wall.

• They share their biochemical properties with other members of the Proteeae family but they can be differentiated from other species by production of hydrogen sulfide gas, liquefaction of gelatin, and inability to swarm on the agar plates. Morganella species also contain ornithine decarboxylase, an enzyme. This enzyme is absent in Proteus species. The species can also ferment mannose sugars.

• The bacteria are naturally resistant to several Beta-lactam antibiotics, which leads to delayed treatment.

What Is the Epidemiology of Morganella Morganii Species?

Though Morganella morganii species are present widely, they are an infrequent cause of community-acquired infections. They are commonly found in nosocomial infections. The bacterium was believed to cause summer diarrhea. But it has been found that the Morganella morganii infection is frequently associated with opportunistic community-acquired diseases. The infection accounts for approximately 0.70 % of bacteremia globally.

What Are the Clinical Signs and Symptoms of Morganella Morganii Infection?

• The most commonly affected sites by M. morganii infection are the skin, intestinal tract, urinary tract, soft tissues of the body, and hepatobiliary system.

• The most frequently occurring clinical infection is the urinary tract infection. M. morganii is the fifth most common cause of urinary tract infections.

• Elderly patients hospitalized for a longer time with long-term catheters are susceptible to acquiring the disease.

• Skin, wound, and soft tissue infections are also caused by morganii.

• Intra-abdominal infections like a liver abscess, biliary infection, etc., are also caused by Morganella.

• It results in a high mortality rate in some infections.

• It can cause sepsis, bacteremia, abscess, osteomyelitis, and even cellulitis.

• The patient may usually present with fever, chills, nausea, vomiting, abdominal pain, lethargy, jaundice, irritability, hyperexcitability, severe body ache, and malaise.

• In exceptionally few rare cases, the infection can be life-threatening.

What Is the Pathogenesis of Morganella Morganii Infection?

• Morganella morganii bacteria possess MR/K hemagglutinin that increases its bond to urinary catheters, thereby increasing its susceptibility to cause urinary tract infections.

• Also, Morganella synthesizes a urease enzyme that makes it prone to grow readily on the urinary catheters, thereby infecting them. The Morganella urease can also be activated at a low pH. This increases the survival rate of bacteria at a considerably low pH.

• Hemolysin is also synthesized by Morganella species. Hemolysin increases the pathogenicity of the Morganella bacterium by breaking down red blood cells due to hydrophilic pore formation in its cell wall.

How Is Morganella Morganii Infection Diagnosed?

The healthcare professional usually recommends the isolation of the bacterium in the laboratory. The bacteria usually form flat, colorless colonies on MacConkey agar and blood agar in laboratory isolation. Bacterial culture is the clinical test to confirm the presence of the causative bacterium. A blood, urine, wound, mucus, or stool sample is usually collected for bacterial culture identification.

What Is the Treatment of Morganella Morganii Infection?

• The healthcare provider mainly opts for antibiotic therapy to cure the Morganella morganii bacterial infection. The antibiotic is usually given depending on the infection site, the host’s immune response, and the pattern of resistance.

• Mostly, Quinolones, third-generation Cephalosporins, Aminoglycosides, and other broad-spectrum antibiotics are the drug treatment of choice for such infections.

• Besides antibiotic therapy, the urinary catheter must be periodically replaced in urinary tract Morganella infections.

• In cases of wound infections, wounds should be debrided sufficiently.

• The intravenous lines must be changed from time to time in case of sepsis or bacteremia.

How to Prevent Morganella Morganii Infection?

In recent years, there has been an increased trend in the antibiotic resistance of Morganella species. Hence, in nursing homes, infection control measures should be executed to limit the spread of the bacterium pathogen. Some such preventive measures involve:

• Washing hands using soap and water frequently.

• Isolation of infected patients in the hospitals.

• Antibiotics should be used effectively with changes in usage policy among infected patients to prevent antibiotic resistance.

• Replacing urinary catheters periodically to prevent the colonization of the microbial pathogen.

Conclusion

Morganella morganii bacterium has recently emerged as a potential superbug with the ability to cause life-threatening bacteremia infections. Certain species of this bacteria have become antibiotic-resistant, thereby increasing the risk of spreading serious nosocomial and blood infections. Therefore, it is important to seek medical advice for prompt treatment. Preventive measures should also be taken by hospitals to prevent the spread of this infective microbial pathogen.