History of antibiotics
The history of contemporary antibiotics was started in the 19th century when Louis Pasteur during his research discovered that certain microorganisms have anti-bacterial activity. Later, the British physician William Roberts observed during his research that certain types of mold that are used to create cheese free the area affected with the mold from any pathogenic bacteria. Both researchers and many others from all around the world continued to study the mechanism of one bacteria elimination with another microorganism. And finally, in 1928, Scottish biologist Sir Alexander Fleming discovered the molecule of penicillin which had antibacterial activity in cheese during the fermentation process. Further research by biochemists and pharmacologists Ernst Chain and Howard Florey, lead to a development of ready-to-use penicillin formula to treat infections in people. In 1942, penicillin was first used as a treatment of Allied military and became widely used after 1945.
When and how antibiotics are used today
Antibiotic medications are used for the therapy of the diseases caused by Gram-positive, Gram-negative, atypical, and anaerobic bacteria. Some of them are also used for the therapy of diseases caused by parasites.
There are several methods of antibiotics administration. The most common way is oral, i.e. pills or capsules are taken by mouth. The treatment is required in a systemic infection which cannot be directly contacted with topical antibiotic medications.
In some infections with an external localization, topical antibiotic preparations can be used such as nose drops, eye drops, ear drops, ointments, and gels. For example, such treatment methods are used for conjunctivitis, sinusitis, acne, and others. The advantages of the topical preparations are: the minimization of the antibacterial drug’s toxic effect on the entire body and steady concentration of antibiotic at the site of infection. The disadvantages are: it can be hard to control if a proper amount of antibiotic is used and there is a possibility of a local allergic reaction.
In the most severe cases, complicated or deep-seated systemic infections, the drugs are given intravenously or by intramuscular injection.
The antibiotics choice for a particular treatment is based on the fact whether the pathogen for the infection is identified or not. If a disease is suspected to be caused by bacteria but the tests to identify the precise pathogen are not made, doctors prescribe broad-spectrum antibiotics, i.e. antibiotic medications that are effective against a wide range of bacteria.
In case susceptibility test to identify the precise pathogen was made, a doctor can appoint definitive therapy course. In this case, a narrow-spectrum antibiotic can be used. Such treatment methods are mostly reasonable in such infections as tuberculosis or atypical pneumonia for which only certain drugs are effective.
Antibiotics are used to cope with acute, chronic, and latent infections. They can be also used to prevent infection during the surgery or in people with lowered immunity such as HIV-positive patients, cancer patients after chemotherapy, and people with an organ transplant. Currently, they are also used to prevent surgery in non-complicated appendicitis.
Methods of contraction of bacterial infections:
This type of infection spread is also known as airborne. Such infections are transmitted through the air in coughing, sneezing, or even simply breathing in the same air as an infected person in a closed space. Such infections are spread this way because the pathogens that cause them are localizing in mucosa of the airways of an infected person and are contaminating the air he or she breathes out. Such infections can be also spread through air dust, i.e. through the dust particles contaminated with the infection. This way of infection spread is possible with the infections that can stay alive for long periods of time in the environment, for example, the bacteria that cause tuberculosis can contribute to such a way of infection spread.
- Direct contact
This method of infection spread is possible when the pathogens of the infection are localizing on the skin, on the mucous membranes of the eyes, mouth, genitals, on the surface of wounds, or are transmitted from them when these infected areas are in contact with other objects. Another individual can get infected through contacting these areas or touching the objects that were in direct contact with the affected areas.
Transmissible mechanism of infection spread is possible when a pathogen that causes the infectious disease is localized in the blood system or lymph. It is a common way of infection spread through the bites of specific and nonspecific carriers, for example, blood-sucking ticks.
Alimentary way of contraction also known as fecal-oral is possible when the pathogen localization in the carrier is in the intestines. The pathogen is excreted from the hosts’ body with feces and vomits and can be contracted in case a healthy individual drinks contaminated water, eats contaminated food, or eats with dirty hands.
This method of contraction occurs during pregnancy. The carrier of the infection (mother) infects the fetus or a baby with the infection that she has.
In bloodborne infection, the pathogen is in direct contact with the blood. It can occur during surgery, injections (especially non-medical), sexual intercourse, blood transfusion, etc.
The transmission of the infection in such a way occurs through bloodborne or direct contact mechanisms but involves a sexual intercourse. This type of infection spread mechanism is so common that it has a separate group of infections – sexually transmitted infections.
Classification of infections
Infection can develop in different directions and take many forms. The form of the infection development depends on the ratio of microorganism pathogenicity, protection against infection of the host organism, and environmental factors.
First of all, all infections are caused either by primary pathogens or opportunistic ones. Primary pathogens can attack a healthy individual and are contagious while opportunistic are infections that attack only people with lowered immune system and otherwise are harmless. For example, opportunistic pathogens can develop on the basis of such conditions as HIV, cancer, transplanted organ, and so on.
Primary infection is the infection that is considered the main cause of the disease. For example, tuberculosis is a primary infection while an infected wound or burn is considered a secondary infection.
Secondary infection is an infection that occurs on the basis of already existing condition, i.e. when a host already suffers from an infectious or other disease. For example, it can develop on the basis of diabetes or in people with liver or kidney dysfunction. It represents one of the forms of immunodeficiency.
Generalized infection is an infection in which pathogens spread mainly through blood and lymph around macroorganism (host).
Localized infection is a local damage to the tissues under the influence of pathogenic factors. The localized process commonly occurs at the place of microbe penetration into the tissue and is usually accompanied with local inflammatory response. Localized infections include tonsillitis, diphtheria, furuncle, and others. In some cases, localized infection can transform into a systemic infection.
Systemic infection is characterized by the penetration of the pathogenic microorganisms in the blood of the host and their further spread throughout the host’s body. Penetrating the tissues of the body, the microbe replicates at the place of penetration and then spreads to the host’s blood. Such mechanism of spread is common for flu, syphilis, some forms of tuberculosis, viral hepatitis, salmonellosis, typhus, and others.
Latent infection is a condition in which the microorganism that lives and replicates in the tissues of the body doesn’t cause any symptoms (for instance, chronic form of gonorrhea, salmonellosis, streptococcus, etc.)
Symptomatic infection is an infection with obvious clinical signs of specific infection.
Focal infection develops as a result of inflammation of a certain organ and is accompanied with the tissue destruction.
The infections are also classified by the localization: upper and lower respiratory tract, upper and lower urinary tract, genital infections, skin infections, odontogenic infection (tooth or tissues around the teeth), and central nervous system.
Stages of bacterial infection development
Incubation period is the time between the invasion of the infectious agent into the host’s body and the first occurrence of infectious disease symptoms’ manifestation. Within this time, the pathogen replicates in the organism, the number of pathogens and its waste products increases up until certain threshold after which the host’s body begins to respond with reactions (symptoms). The period can range from a few hours and days to a number of years.
Prodromal period comes after the incubation. During this period, usually, the first infectious disease symptoms start to manifest but they are not yet clinically specific nor severe. The common symptoms that manifest during this stage are general weakness, headache, and fatigue. The length of this period usually doesn’t’t exceed 24-48 hours.
Disease development period is characterized by the first manifestations of certain infection or common for the majority of infectious diseases symptoms such as fever, inflammatory focus, chills, and others. During the symptomatic period two stages of symptoms development can be identified: disease flourishing and symptoms fade.
Reconvalescence period is the time when the patient recovers. It can be quick when the recovery happens after a crisis or slow when the recovery is achieved through lysis. During this stage, the infection can transform into a chronic one. In successful cases, the symptoms disappear quicker than the body organs and tissues’ functions fully restore and the complete elimination of the infectious agent from the organism is achieved. The recovery can be also full or accompanied with the development of complications, for example, from the side of the nervous, musculoskeletal or cardiovascular systems. The period of the pathogen elimination from the infected person’s body can be extended and for certain infections it can last for decades, for example, in tuberculosis and typus.
Signs and symptoms
The problem with bacterial infections symptoms is that they can be the same as in the viral infections. For example, acute sinusitis has the same symptoms as viral influenza. But in case with flu, it is easy to know when you should take antibiotics to cope with bacterial infection. Usually, if the flu symptoms do not fade over 5-7 days, it means that you have already developed bacterial complication and need the wide-spectrum antibiotics. However, with other infections, such as genitourinary tract infections, lung infections, and others, it is harder to know without a proper diagnosis which treatment a patient needs.
Considering that the bacterial infections can attack various parts of the body, they have different symptoms. Nevertheless, in the acute phase they have common manifestation: fatigue, appetite loss, general weakness, fever, chills, aches, and others. If the infection is localized on a certain area, such symptoms as swelling, flushing of the skin or mucosa, rash and localized pain can be observed.
Some infections can be asymptomatic in a host but cause a disease in an individual who contracts the infection from the host. In such cases, it is considered that the first individual is a carrier who doesn’t have an infectious disease but has only an infection.
Diagnosis of infectious diseases
The diagnosis of infectious disease can be made based on a physical examination only or further tests. For example, an otolaryngologist can identify tonsillitis without additional tests besides examination of the patient and the symptoms reported. In this case, the precise pathogen is not identified and the doctor can use an empiric approach prescribing the patient broad-spectrum antibiotic medication.
If for a successful treatment it is crucial to find out the precise pathogen or which antibiotics can treat it, biochemical and susceptibility tests are made. The first one is based on the analysis of the presence of certain enzymes in the blood that indicate the infestation with a certain pathogen. The second test is made to identify whether the bacteria that caused the disease is susceptible for the antibiotic your doctor chooses for you.
For some infections x-ray is needed. For example, it is used to see if there are changes in the lungs typical for tuberculosis or pneumonia. If the tests show that there are typical signs, further study of sputum is made to confirm the diagnosis.
Prevention of infectious disease
Though medical advances allow treating the majority of known infections, the most effective and common way to prevent infectious disease nowadays is frequent hand washing with soap. Although, during the medical procedures aseptic techniques play a special role in prevention of the infection spread from doctors to patients and vice versa and from one patient to another.
The introduction of aseptic technique in the 19th century substantially reduced the number of cases of infectious diseases acquired during surgeries and other invasive medical procedures. The technique includes the sterilization of medical tools, use of antiseptics, masks, overshoes, and gloves.
Other measures to prevent infection include the strengthening of immunity through a healthy diet, exercising, and taking vitamins and supplements that may be lacking in your diet. It is also important to cook meat and fish for sufficient time so the probable pathogens will be eliminated and do not cause any disease in you. As for the water, it is highly advised to drink filtered water and stick only to bottled water if you travel to the regions infamous for poor quality of running water.
The sexually transmitted infections are prevented by using condoms. Other serious infections can be avoided refraining from using illegal drugs and services of uncertified physicians and dentists.
To avoid complications of a viral infection during the flu season, if you get infected, comply with bed rest and take medications to eliminate the symptoms. Such therapy can prevent the development of bacterial infection of lungs, throat, nose, and brain.
Medical substances to prevent infection are the following:
- Antiseptics are used to prevent the infestation of the wound or cuts and are applied to the skin.
- Disinfectants are used to clean and disinfect surfaces on which pathogens can be found, i.e. surgical table, bedclothes, cutlery, and so on.
In some cases, to prevent the infection antibiotics are used.
Management with medications
Based on the severity of infection your doctor can prescribe you one or several antibiotics. The treatment course length is usually based either on your doctor suggestions or repeated tests that indicate the effectiveness or ineffectiveness of the drug. For example, tuberculosis treatment can be performed for years before the pathogen is fully eliminated from the body. Doctors prescribe different antibiotics, usually, a combination of several drugs, to avoid bacteria resistance and frequent tests to see if the treatment should be continued or changed.
In the least severe infections, the treatment course can vary from 3 to 10 days. However, you should remember that even if the symptoms go away before you ended the treatment course, you should still take the pills or get injections till the last day of the treatment prescribed by your doctor or indicated in the instruction. First of all, even if the symptoms are gone the infection can be still there and exacerbate or turn into chronic after just a couple of days you stop using the medication. Secondly, if the course is incomplete and the bacteria is still there, you cannot resume the treatment with the same medication as there is a very high chance that the bacteria will develop resistance to this particular medication.