Bacteriology Lecture 12

Brucella Bacteria

• Brucella bacteria are gram-negative, motile, and aerobic, with a capsule.
• They are intracellular parasites and can survive within host cells.
• There are four main species of Brucella bacteria: Br. abortus, Br. suis, Br. canis, and Br. melitensis, which can cause disease in humans.

Brucellosis Disease

• Brucellosis is a zoonotic disease, meaning it can be transmitted from animals to humans.
• The disease can be transmitted through consumption of contaminated dairy products or direct contact with infected animals.
• Symptoms of brucellosis include fever, sweating, fatigue, and weight loss, and can take 2-3 weeks to develop.
• The disease can cause inflammation in various parts of the body, such as the lymph nodes, liver, and spleen.

Lab Diagnosis of Brucellosis

• The bacteria can be isolated from blood cultures or tissue samples.
• Serological tests, such as the Brucella agglutination test, can detect the presence of antibodies against Brucella.
• PCR (polymerase chain reaction) can also be used to detect the bacteria.

Treatment of Brucellosis

• The treatment of brucellosis typically involves a combination of antibiotics, such as doxycycline and rifampicin.
• The treatment can be prolonged and may take several weeks to months.

Yersinia Pestis Bacteria

• Yersinia pestis bacteria are gram-negative, bipolar staining, and have a capsule.
• They are facultative anaerobes and can grow on nutrient-rich media.
• The bacteria can cause bubonic plague, pneumonic plague, and septicemic plague.

Plague Disease

• Plague is a zoonotic disease, primarily affecting rodents and other small mammals.
• The disease can be transmitted to humans through the bites of infected fleas or direct contact with infected animals.
• Symptoms of plague include fever, chills, and swollen lymph nodes, and can take 1-7 days to develop.
• The disease can cause pneumonia, meningitis, and septicemia.

Lab Diagnosis of Plague

• The bacteria can be isolated from blood cultures, lymph node aspirates, or tissue samples.
• Serological tests, such as the Yersinia pestis agglutination test, can detect the presence of antibodies against Yersinia pestis.
• PCR can also be used to detect the bacteria.

Treatment of Plague

• The treatment of plague typically involves a combination of antibiotics, such as streptomycin and gentamicin.
• The treatment can be prolonged and may take several weeks to months.

Bacteroides Bacteria

• Bacteroides bacteria are gram-negative, anaerobic, and have a capsule.
• They are normally found in the human gut and can cause infections in various parts of the body.
• There are several species of Bacteroides bacteria, including B. fragilis, B. corrodens, and B. melaninogenicus, which can cause disease in humans.

Infections Caused by Bacteroides Bacteria

• Bacteroides bacteria can cause infections in the mouth, throat, lungs, and abdomen.
• They can also cause abscesses, sepsis, and meningitis.
• The bacteria can enter the body through wounds, surgical incisions, or Medical instruments.