Microbiology: Tuberculosis and Rickettsial Infections

A type of tuberculosis caused by ingesting contaminated milk.

A form of tuberculosis that affects the lungs.

A form of tuberculosis that affects areas outside the lungs.

The primary site of infection in the lungs, where the bacteria first replicate.

A protective structure formed by the immune system to contain the bacteria.

A type of granuloma that contains giant cells.

The reactivation of a primary infection, leading to a spread of the disease.

Leprosy is caused by the bacteria Mycobacterium leprae, also known as Hansen's Disease.

Leprosy is a slow-growing infection with an average incubation period of 1 year and up to 20 years.

Leprosy is transmitted through prolonged close contact with individuals with lepromatous leprosy who shed the bacteria through nasal secretions and skin lesions.

The optimal growth temperature for Mycobacterium leprae is 30°C, which is lower than body temperature. Therefore, it prefers cooler areas like the skin, nose, eyes, and superficial nerves.

The immune response of an individual determines the type of leprosy they develop. This variation in immune response explains the diverse clinical manifestations of leprosy.

Leprosy can be progressive, leading to permanent damage to the skin, nerves, limbs, and eyes if left untreated. The disfiguring appearance of the disease is due to skin anesthesia, bone resorption, and thickening of the skin and nerves.

Dapsone with rifampin and clofazamine are commonly used to treat leprosy for at least two years until the lesions are free of bacteria.

Leprosy can be prevented by isolating patients with lepromatous leprosy, treating infected individuals, and administering chemoprophylaxis with dapsone to exposed children.

While a vaccine for leprosy is not currently available, the BCG vaccine provides partial protection against the disease.

The smallest free-living organisms that lack a cell wall.

Mycoplasma infections are not affected by antibiotics that target cell wall synthesis.

Mycoplasma infections are difficult to treat because they require special growth conditions and take a long time to cultivate.

Mycoplasma pneumoniae causes atypical pneumonia, attaching to the respiratory tract and inhibiting ciliary action.

Mycoplasma pneumoniae is transmitted through respiratory droplets, often in crowded settings.

Tetracycline antibiotics are effective against Mycoplasma infections because they inhibit protein synthesis.

Mycoplasma infections can cause a variety of symptoms, including pharyngitis, bronchitis, and pneumonia.

Mycoplasma pneumoniae can lead to the production of autoantibodies that cause hemolytic anemia.

Mycoplasma infections are more common in winter and often occur in outbreaks among families and students.

Mycoplasma pneumonia is often called "walking pneumonia" because it causes milder symptoms than other types of pneumonia.

These are the most common bacterial sexually transmitted infections (STIs) worldwide. They are obligate intracellular pathogens with a rigid cell wall and are often stained with Giemsa stain.

They are infectious, metabolically inert, and enter host cells, where they reorganize into a larger, active form. They are non-infectious, metabolically active, and reproduce through binary fission. When conditions are right, they revert to the infectious form to start the cycle again.

Chlamydia trachomatis can cause serious eye infections like trachoma, which can chronically recur and potentially lead to blindness.

Chlamydophila pneumoniae causes atypical pneumonia, while Chlamydophila psittaci causes psittacosis, commonly known as 'parrot disease.' The differences in their molecular structure led to their reclassification from Chlamydia to Chlamydophila.

It's important to be aware of the potential for zoonotic transmission of these bacteria, especially from birds. Psittacosis, caused by Chlamydophila psittaci, can be contracted by humans.

Atypical pneumonia refers to pneumonia caused by bacteria that cannot be easily grown in standard laboratory cultures, leading to a disease with distinctive symptoms like milder presentation, prolonged duration, reduced sputum production, and extra-pulmonary complications.

Mycoplasma pneumonia, a common cause of atypical pneumonia, is known for being difficult to culture in standard laboratory conditions. It's often associated with a unique set of symptoms.

The 'Cold agglutinin test' detects IgM autoantibodies that clump red blood cells at low temperatures (4°C) but not at normal body temperature (37°C). While a positive result can suggest Mycoplasma pneumonia, it's not entirely specific and can be seen in other infections.

Rickettsiae are a group of bacteria that are obligate intracellular parasites, meaning they can only survive and multiply inside the cells of a host. They are pleomorphic, meaning they can take different shapes like cocci, rods, or filaments, and are often found singly or in pairs.

Rickettsiae are divided into two main groups based on their mode of transmission: The Typhus Group and the Spotted Fever Group.

The Typhus Group of Rickettsiae includes louse-borne epidemic typhus (associated with famine and war), flea-borne endemic typhus, and tick-borne Rocky Mountain spotted fever.

Rickettsiae are transmitted through the bites of ectoparasites like lice, fleas, and ticks. These parasites can also introduce infectious fluids or feces into the skin or spread through inhaled infectious particles.

Common symptoms of Rickettsial infections include fever, headache, rash, malaise, hypotension, respiratory distress, and kidney failure.

The Weil-Felix Reaction is a serological test used to diagnose Rickettsial infections. This test relies on the cross-reactivity between antibodies in the patient's serum and antigens from the bacteria Proteus vulgaris. While not specific to Rickettsiae, it can provide useful diagnostic information.