Optochin Susceptibility Test- Principle, Procedure, Results


Pneumococcus, also known as Streptococcus pneumoniae, is a type of bacteria that can cause various infections in humans, especially in the respiratory tract. Pneumococcus is one of the most common causes of community-acquired pneumonia, which is a lung infection that occurs outside of hospitals or other health care facilities. Pneumococcus can also cause other diseases, such as sinusitis, otitis media, meningitis, sepsis, and more.

Pneumococcus is a Gram-positive, spherical bacterium that usually appears in pairs (diplococci) under the microscope. It has a polysaccharide capsule that protects it from being recognized and destroyed by the immune system. There are more than 100 different types (serotypes) of pneumococcus, and they vary in their ability to cause disease (virulence), their prevalence in different regions of the world, and their resistance to antibiotics.

Pneumococcus can be found in the nose and throat of healthy people, who are called carriers. Carriers do not have any symptoms of infection, but they can spread the bacteria to others through respiratory droplets when they cough or sneeze. Pneumococcus can also be transmitted by touching contaminated surfaces or objects.

Pneumococcus can cause infection when it invades the tissues or blood of a susceptible person. Susceptibility depends on several factors, such as age, immune status, underlying medical conditions, and previous exposure to pneumococcus or its vaccine. Some people are more likely to get sick from pneumococcus than others, such as young children, older adults, people with chronic diseases (such as diabetes, heart disease, lung disease, or HIV), and people who have weakened immune systems (such as those who have had organ transplants, cancer treatment, or spleen removal).

Pneumococcal infections can range from mild to severe and life-threatening. The symptoms and complications depend on the type and site of infection. Some common signs and symptoms of pneumococcal infections are:

  • Fever
  • Cough
  • Chest pain
  • Shortness of breath
  • Sputum production
  • Headache
  • Stiff neck
  • Confusion
  • Ear pain
  • Nasal congestion
  • Facial pain or swelling

Pneumococcal infections can be diagnosed by taking samples of body fluids (such as blood, sputum, cerebrospinal fluid, or middle ear fluid) and testing them for the presence of pneumococcus or its antigens. Pneumococcus can be identified by its characteristic appearance on Gram stain (lancet-shaped diplococci), its sensitivity to optochin (a chemical that inhibits its growth), and its solubility in bile (a substance that dissolves its capsule). Pneumococcus can also be typed by its serotype using specific antibodies or molecular methods.

Pneumococcal infections can be treated with antibiotics, but some strains of pneumococcus have become resistant to many commonly used drugs. Therefore, it is important to choose the appropriate antibiotic based on the local patterns of resistance and the results of susceptibility testing. In some cases, additional treatments may be needed to manage the complications of pneumococcal infections, such as oxygen therapy, fluid replacement, surgery, or intensive care.

Pneumococcal infections can be prevented by vaccination and by avoiding exposure to the bacteria. There are two types of vaccines available for pneumococcus: a polysaccharide vaccine (PPSV23) that covers 23 serotypes and a conjugate vaccine (PCV13) that covers 13 serotypes. The vaccines are recommended for different groups of people based on their age and risk factors. The vaccines can reduce the incidence and severity of pneumococcal infections, but they cannot prevent all cases or eliminate carriage of the bacteria. Therefore, it is still important to practice good hygiene measures, such as washing hands frequently, covering coughs and sneezes, and staying away from sick people.

Pneumococcus is a major public health problem worldwide, causing millions of cases and deaths every year. It is estimated that pneumococcus is responsible for about 15% of all pneumonia cases, 50% of all bacterial meningitis cases, and 40% of all sepsis cases globally. Pneumococcus also contributes to the burden of antimicrobial resistance, as it is one of the most common bacteria that develop resistance to multiple drugs. Therefore, it is essential to monitor the epidemiology, microbiology, and pathogenesis of pneumococcus and to implement effective strategies for its prevention and control.