UNIVERSITY OF SAINT LOUIS-TUGUEGARAO
SCHOOL OF HEALTH AND ALLIED SCIENCES
CODE 298: Clinical Bacteriology (Lecture)
1. A 45-year-old man was seen in the emergency department with
fever, chills, nausea, and myalgia. He reported that 2 days earlier
he had eaten raw oyster at a popular seafood restaurant. On the
admission, he had a febrile and hemorrhagic, fluid – filled
bullous lesions on his left leg. The patient has history of
diabetes mellitus and a chronic hepatitis b and heavy alcohol
intoxication. The patient’s temperature was 39.2 degree Celsius.
He has a culture test showing a curved gram-negative rod from
his blood culture, and the third day of admission, he developed
Disseminated intravascular coagulation and died.
A. What is the probable diagnosis?
•
The patient suffered vibriosis which can cause watery diarrhea, often
accompanied by abdominal cramping, nausea, vomiting, fever, and chills. It
explains the case of the old man very well since, the symptoms of vibriosis
occur within 24 hours of ingestion and last about 3 days. And according to
studies, severe illness is rare and typically occurs in people with a weakened
immune system. Taking into consideration that the old man has history of
diabetes mellitus and chronic hepatitis b, and his heavy alcohol intoxication, his
immune system was already at a downfall.
B. What is the causative agent? Explain your answer.
•
•
The causative agent would be Vibrio species, but to be more specific, Vibrio
vulnificus. As stated in the case, the culture test result showed a curved gramnegative rod from his blood culture which is parallel to the description of Vibrio
species, since they are curved, gram-negative rods commonly found in
saltwater. Vibrio bacteria naturally inhabit in coastal waters where oysters live.
And because oysters feed by filtering water, bacteria can concentrate in their
tissues. When raw or undercooked oysters are ingested, viruses or bacteria
that may be in the oyster can cause serious illnesses like vibriosis.
This also explains the febrile and hemorrhagic, fluid – filled bullous lesions on
his left leg, because vibrio bacteria can also cause a skin infection when an
open wound is exposed to salt water or microorganism of salt water, especially
bacteria.
C. What culture media and biochemical tests would help confirm your
answer?
•
Routine stool, wound, and blood cultures aid in the diagnosis of V vulnificus
infection. As said in the case, the old man underwent a blood culture, which
strengthens the case of vibriosis. On the other hand, biochemical tests that
support this medium would be through preliminary identification which is
based on colony appearance on Thiosulfate Citrate Bile Salts (TCBS) agar.
Strains of Vibrio spp. produce yellow colonies on TCBS Agar because of
fermentation of sucrose.
REFERENCES: Centers f or Disease Control and Prevention
National Center f or Emerging and Zoonotic Inf ectious Diseases (NCEZID)
UNIVERSITY OF SAINT LOUIS-TUGUEGARAO
SCHOOL OF HEALTH AND ALLIED SCIENCES
CODE 298: Clinical Bacteriology (Lecture)
Division of Foodborne, Waterborne, and Environmental Diseases
2. An 81-year-old female was admitted to the hospital for a total
knee arthroplasty. After the surgical procedure she had no postoperative complications and a successful recovery. Two years
later, while living independently at home, she began to
experience chronic, daily pain in the knee and joint. To control
the pain, she would take acetaminophen every several hours as
directed. She finally presented to her orthopedic surgeon after
a 2-month history of the pain. She could not recall any injury or
change in activity that may have initiated the pain. Physical
examination of the knee and joint demonstrated moderate
swelling and mild erythema of the artificial joint. She
experienced increased pain with weight bearing and passive
range of motion. A new xray revealed no acute fractures or
deformities but did reveal a small effusion, indicating the need
for an arthrocentesis. Joint fluid revealed no crystals, 110,000
white blood cells, and 25,000 red blood cells. Gram stain of the
synovial fluid revealed gram-positive cocci.
A. What is the clinical significance of the microscopic results- crystals,
Gram Stain, WBC and RBC counts?
•
The microscopic results of the joint fluid analysis are significant in identifying
the underlying cause of the knee pain. The absence of crystals rules out gout
or pseudogout as possible causes of the pain. The elevated white blood cell
count (110,000) and red blood cell count (25,000) suggest an inflammatory
response and possible joint damage. The presence of gram-positive cocci on
the Gram stain indicates a bacterial infection, which may have caused the
inflammation and pain in the joint.
B. What is the probable diagnosis? Why?
•
The probable diagnosis is a bacterial infection of the knee joint, also known as
septic arthritis. The symptoms of chronic pain, swelling, erythema, and limited
range of motion are consistent with septic arthritis. The elevated white blood
cell count and presence of bacteria on the Gram stain confirm the diagnosis.
C. What is the causative agent the disease? Explain your answer.
•
The causative agent of septic arthritis can be any bacteria, but the presence of
gram-positive cocci suggests Staphylococcus aureus as the most likely
pathogen. Staphylococcus aureus is a common cause of septic arthritis and is
commonly found on the skin.
D. What culture media/biochemical test/ other method would help confirm
your answer in C. Elaborate your answer
UNIVERSITY OF SAINT LOUIS-TUGUEGARAO
SCHOOL OF HEALTH AND ALLIED SCIENCES
CODE 298: Clinical Bacteriology (Lecture)
• A culture of the joint fluid can be done to identify the causative organism and
determine antibiotic sensitivity. The fluid can be cultured on blood agar,
chocolate agar, or thioglycollate broth to grow aerobic and anaerobic bacteria.
Biochemical tests such as catalase, coagulase, and mannitol fermentation can
be used to identify Staphylococcus aureus.
References: Pseudogout - Symptoms and causes. (2022, July 28). Mayo Clinic.
https://www.mayoclinic.org/diseases-conditions/pseudogout/symptoms-causes/syc20376983
Ferrand, J., Samad, Y. E., Brunschweiler, B., Grados, F., Dehamchia-Rehailia, N.,
Séjourne, A., Schmit, J. L., Gabrion, A., Fardellone, P., & Paccou, J. (2016, June 1).
Morbimortality in adult patients with septic arthritis: a three-year hospital-based study.
PubMed Central (PMC). https://doi.org/10.1186/s12879-016-1540-0
Pseudogout - Symptoms and causes. (2022, July 28). Mayo Clinic.
https://www.mayoclinic.org/diseases-conditions/pseudogout/symptoms-causes/syc20376983
Group Member:
Jeremy Kanagendaran
Javen Nueva Espana
Justine Barquin
Mv Iringan