Differential diagnosis of Listeria monocytogenes

Abstract

Dannon Wise, a 79-year-old female living in a nursing home presents confusion and refusal to drink and eat. Examinations show sign of pneumonia. From the patient history, demographics and laboratory diagnosis, it is quite conclusive to say that the patient suffers from Listeriosis an infection from Listeria monocytogenes. The pathology of the infections and the factors affecting vulnerability is part of the discussion in this paper. Also discussed, is the differential diagnosis that led to the conclusion in the diagnosis.

Medical case study

Dannon Wise, a 79-year-old female living in a nursing home presents confusion and refusal to drink and eat. Examinations show sign of pneumonia. The patient also displays signs of lethargy and is very febrile. The history of the patient reveals osteomyelitis of the foot, kidney disease, heart failure, diverticulitis, and diabetes. She also had a history of alcoholism and heavy smoking. Gram-stained smear revealed gram-positive bacilli whose culture morphology was small, smooth translucent colonies with a narrow zone of beta hemolysis.

Discussion

The diagnosis was that the patient suffered from Listeria monocytogenes infection. The bacterium is an infection that commonly infects pregnant women, neonates and elderly individuals who are immunocompromised. It is a food-borne infection whose major clinical pathologies include diarrhea, fever, nausea, and vomiting. The identification characteristics include motile, non-spore forming, gram-positive rods that grow an anaerobically and catalyzes lactose. It grows best at neutral pH and a wide range of temperatures. It is beta-hemolytic and gives a blue-green sheen on blood agar. Infections mostly occur through the oral route and the immune response to the bacteria is through activation of T-cells in macrophages and interleukin-18. CNS manifestations are meningitis and meningoencephalitis while local infections show sepsis, osteomyelitis and pneumonia in rare cases.

The infection is mistakable with infection from Group B streptococci. This bacterium also infects immunocompromised adults such as the elderly and pregnant women and neonates. The infection is the most common cause of sepsis and meningitis. It afflicts adults with certain immunocompromised conditions like diabetes, heart disease, obesity, and cancer. The infection rates increase with age and develops sepsis, osteomyelitis, pneumonia and urinary tract infection. Rarely causes meningitis. The definitive diagnosis is still quite similar to Listeria monocytogenes in the use of isolation techniques from body fluids such as blood or CSF (Cerebral spinal fluid) and sometimes urine. The infection rate is also high in adults living in nursing homes. In non-pregnant adults, the most common pathology is sepsis, pneumonia, abscesses and infections of the bone. Pneumonia leads to shortness of breath and fever.

These two organisms resemble each other in various morphological and biochemical characteristics. The differences in macroscopy and microscopy of solid media show size differences and length of the organisms. When faced by these two organisms one would look for chaining to determine the presence of Streptococcus agalactiae. On the other hand, L. monocytogenes show resistance to furadantin.

Major differential steps

Listeria monocytogenes - is facultatively anaerobic, gram-positive coccobacillus with a size of 0.5 to 2 micrometers diameter. It can thrive in low temperatures with a pH range between 4.3 and 9.6. The bacterium reproduces at very wide range of temperatures from 10c to 450c. However, the bacterium is quite different from Group B strep in that it is motile, and GBS is not motile. It is also catalase and oxidase positive unlike the other bacterium. These are the major differential features between these two bacteria. Treatment of the infection is by broad-spectrum antibiotics and the most active against the bacterium is ampicillin and amoxicillin. Gentamycin is usually useful later to kill the infection completely. The infection is highly susceptible to adults with immunocompromized conditions like diabetes, heart diseases and renal conditions as well as a history of alcoholism like in the case of the patient, Dannon Wise. Also, infections increase with the increase with age especially in people above 65 years of age.

Streptococcus agalactiae- is a gram positive and facultative anaerobe but usually found in chains of up to 50 cells and even more. The size range is between 0.5 and 1.0 micrometers in diameter. It is b-hemolytic on blood agar. The reason the bacterium is not the final diagnosis, in this case, is because the bacterium is catalase and oxidase negative and immotile, unlike Listeria monocytogenes. Also, the shape of the bacterium is completely coccus. The bacterium is also susceptible to ampicillin and an aminoglycoside. However, it is resistant to clindamycin and macrolides.

Conclusion

Listeria monocytogenes is a not- fastidious bacterium that grows well on cultivation media. It has formations of small colonies about 1-2 mm within 24hrs of incubation. The colonies formed are b-hemolytic with narrow zones of hemolysis. The bacterium is gram-positive and rod-shaped and causes listeriosis that is a food-borne infection. The rates of infection are high in newborns and pregnant women as well as the elderly especially in nursing homes. They grow both at refrigerated temperatures and body temperatures. The case of Dannon Wise fits perfectly into Listeria monocytogenes infection because she has a history of alcoholism, diabetes, kidney failure diseases that make her vulnerable to the infection. Also, a factor is her age because the infection rates increase with age.

Carolyn Morgan is the author of this paper. A senior editor at Melda Research in nursing research paper writing service. if you need a similar paper you can place your order for a custom research paper from custom nursing writing service.

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