Factors Affecting Bacteria Growth

Bacteria constitute the largest form of life on earth. They are found everywhere; in bodies of living or dead animals and plants, all forms of organic matter, in water, dust, soil, and air. While some bacteria are useful to man, many are extremely harmful. Those that are not usually harmful to man at the sites they inhibit are called Commensals, while harmful ones are called Pathogens. Knowledge of conditions that affect bacteria growth is important in the maintenance of food hygiene.

Air and darkness

Bacteria growth is affected by darkness or reduced light. Bright light slows down the living or metabolic activities of bacteria. Also, most bacteria need air to survive while some can metabolize in the absence of oxygen. Those that require oxygen to live actively are called Aerobic bacteria (aerobes) e.g. Staphylococci and Salmonella, while those that survive without oxygen are known as anaerobes. E.g. Clostridium Botulinum and Clostridium Perfringens.

Food

Living organisms require food substances to metabolize and give energy. Bacteria as living organisms are by no means different. Incidentally, food spoilage or food poisoning organisms thrive best on foods that are most often preferred by human beings such as meat, eggs, milk, and their products. Therefor protein-based foods are the most favorable media for bacteria metabolism provided that environmental conditions are conducive.

PH (Acidity or Alkalinity)

Bacteria thrive actively at neutral PH of 7.0. Which is exactly the PH of the human body. The implication is that the human body is a conducive environment for bacterial growth.

Temperature

Each kind of bacterium has a peculiar temperature at which its activity is greatest (known as its optimum temperature). Bacteria can be grouped into three based on three different temperature ranges in which they can survive or metabolize. They are
Mesophylls- they thrive at an optimum temperature of 37^oC   or 96.8^oF (body temperature). They cause food poisoning and are responsible for food spoilage. 
Psychrophilic bacteria grow below 20^oC. Some cause food spoilage at temperature of the domestic refrigerator.
Thermophiles bacteria grow best at quite hot temperatures of up to 60^oC (140^oF). Thermophiles are prolific in food canning.

Time

Bacteria multiply rapidly but still, they need certain time to grow sufficiently to cause illness in man. Under ideal conditions one bacterium divides into two every 20 to 30 minutes.

Moisture or water

Bacteria like all living organisms need water for metabolism. Most cooked foods contain enough moisture to stimulate bacteria growth. However, bacteria cannot multiply in dried or dehydrated foods, rather they remain dormant till they gain moisture or that water is added and they revive again. Similarly water has a higher concentration of dissolved substances than the bacteria cytoplasm. Hence it causes water to flow out of the bacteria by the principle of osmosis, as a result they get dehydrated. 
Based on the above principle, some foods are dried while salt and sugar are added as a food preservation method. However certain bacteria spores can remain dormant in dehydrated conditions but may revive to vegetative form when favorable conditions return. Foods that have high water content such as creams, sauces, jellies and custards are ideal for the growth of bacteria.

Tinea Pedis

 Tinea Pedis or athlete's foot is a fungal infection that affects the foot and may affect anyone. It is most common in warmer climates and summer months, where it can quickly multiply. This is why the infection is commonly associated with sports and athletes. The reason is that it thrives and grows perfectly in warm, moist environments, such as socks and shoes, sports equipment, and locker rooms.

Symptoms

The infection may behave differently depending on the specific fungus that is infecting the skin. Also, the symptoms may vary slightly from person to person. The symptoms include redness or blisters on the affected area, the infected skin may be soft, or layers may start to break down, peeling or cracking skin (the skin may scale and peel away), itching, stinging, or burning sensations in the infected area.

Prevention

As a preventive measure, allow the feet plenty of air to breathe and keep them clean and dry. Always wear sandals in public places.

Treatment

The infection is often treated with topical anti fungal ointments. Severe infections can require additional oral medications as well. The feet will also need to be cared for and kept dry to help kill the fungus.

Atypical Pneumonia

Atypical Pneumonia is a lower respiratory tract infection caused by some types of bacteria namely Mycoplasma pneumoniae, Chlamydophila pneumonia, Legionella pneumophila and rarely Chlamydophila psittaci, which is contracted from infected birds.

Mycoplasma Pneumoniae usually infects people below 40yrs with mild pneumonia symptoms such as earaches, headaches, and a sore throat. Chlamydophila pneumoniae is common in school-aged children and young adults. Legionella pneumophila sometimes called Legionnaires' disease is more severe and most often infects older adults, smokers, and those with weakened immune systems.

Mode of Spread

Atypical pneumonia is a contagious disease, spreading through close contact with an infected person. Coughs and sneezes that contain the infectious pathogens pass through the air from person to person. Also, the bacteria can survive on a person's hands and spread if they rub their eyes or touch their mouth. Legionnaires' disease usually occurs after breathing in droplets of infected water, rather than through close contact with infected people. Atypical pneumonia can infect anyone. However, people most vulnerable to the infection are people above 65yrs, those with impaired immune systems, smokers, children under the age of two, those with chronic respiratory condition, people that live or work in places prone to outbreaks of atypical pneumonia such as nursing homes, schools and college dorms, hospitals, military barracks and other public places.

Symptoms

The symptoms of atypical pneumonia may vary depending on the type of bacteria causing the infection. Usually symptoms of atypical pneumonia begins slowly. It takes longer to appear compared with other common infections such a common cold, flu viruses and typical pneumonia. An infected person may not notice symptoms until 1-4 weeks after exposure to the infection. Once symptoms emerge, they tend to get worse over the next 2-6 days.

Symptoms may include sore, dry, or itchy throat; chest pain when breathing deeply; Persistent cough that may come in fits during the day; flu-like symptoms, such as fever, chill, or cold sweat; persistent headache; aches and pains in the muscles and joints; weakness or fatigue. An infected person may also experience secondary conditions, such as rashes or ear infections, especially if they have a weakened immune system.

Treatment

Usually, the infection presents mild symptoms than typical pneumonia, and the infection may go away on its own. However, severe infections can require hospitalization. Anyone with symptoms of atypical pneumonia should consult a doctor.