Зміст
Legionella pneumophila bacteria are widely distributed in the environment. To limit the spread of legionella infections, reservoirs of bacteria must be eliminated. This can be achieved by regularly disinfecting the building’s water supply, for example by heating water above 70 °C. You cannot get the bacteria from another person or through drinking water
Legionellosis – causes and most common sources of infection
They occur naturally in aquatic environments such as lakes, pools, ponds, streams, and damp places such as damp soil. They are also present in all kinds of water and sewer systems in every building. The development of bacteria is facilitated by the rust accumulating inside the pipes. The optimal growth temperature of bacteria is 35 °C (range 25-45 °C), and the temperature of their destruction is 60-65 °C. Infection with the pathogen can progress to an acute infection – Legionnaires’ disease, manifested by severe pneumonia, or a milder form – Pontiac fever.
Legionella has been confirmed to be found in:
- showers and washbasins,
- air conditioners and humidifiers,
- whirlpool baths,
- swimming pools, thermal pools, jacuzzi,
- decorative fountains and water features such as water curtains or city taps for drinking water,
- hot water tanks and heaters,
- large, complex hydraulic systems,
- car washes,
Curiously, legionella can develop in a reservoir of car windshield wiper fluid, especially if the reservoir is filled with, for example, water, and not real glass cleaner containing a specific set of chemicals. In hospitals, patients who require breathing apparatus, such as a ventilator, are at a higher risk of contracting bacteria.
What promotes the growth of Legionella pneumophila bacteria?
Factors favorably influencing the colonization of bacteria that cause acute pneumonia are, first:
- temperature in the range of 25-45°С,
- low concentration of disinfectants,
- rust in pipes,
- stagnant water, especially rich in calcium and magnesium salts,
- iron and manganese ions and high levels of carbon dioxide,
- the presence of algae, protozoa, biofilms.
It takes 2 to 6 days for Legionella pneumophila to grow. Studies have shown that bacteria can survive for about 20 minutes at 55 °C and for 2 minutes at 5 degrees higher, i.e., 60 °C. Unfortunately, legionella is a spore-forming bacterium that is able to survive in low temperatures until environmental conditions improve in order to attack in an optimal way.
How can you get Legionnaires’ disease?
Legionella enters the body by airborne droplets or inhaled aqueous aerosol. When drinking water contaminated with bacteria, there is practically no risk of infection. You cannot catch Legionnaires’ disease from another person.
The bacterium enters the lungs, where it is absorbed by the cells of the immune system – macrophages. The role of these cells is to fight pathogens through the so-called phagocytosis. Unfortunately, legionella is able to skillfully bypass immune mechanisms and lead to severe respiratory infections.
What are the symptoms of Legionnaires’ disease?
As mentioned, Legionella pneumophila bacteria can cause two different symptoms of infection: Legionnaires’ disease or Pontiac fever.
Pontiac’s fever is a flu-like infection with a so-called self-limiting, that is, mild, that may not require any treatment. Symptoms of infection may appear from about a few hours to 3 days after the bacteria enter the body.
The symptoms of Pontiac fever resemble those of a mild fever, the flu:
- heat,
- chills,
- labored breathing,
- tiresome dry cough,
- general weakness and fatigue of the body,
- headache, muscle and joint pain,
- sometimes – nausea, vomiting, diarrhea.
With Pontiac fever, the patient may feel this way for 2 to 5 days. After this time, the disease disappears.
Worse is the situation with legionellosis, which for some can be a fatal disease. Statistics show that the mortality rate from this infection varies and depends, among other things, on the age of the patient and the presence of other chronic diseases, as well as whether the person smokes, which puts additional strain on the respiratory system. Different sources give different numbers. The mortality rate ranges from 10% to 80%, depending on the aforementioned aggravating factors.
Symptoms of legionellosis are similar to those observed in severe cases of the disease. Pneumonia:
- headache,
- pain in muscles and joints,
- high fever, chills,
- difficulty breathing, shortness of breath,
- chest pain,
- cough – dry, stubborn at first and over time, a wet cough is accompanied by expectoration of sputum (maybe bloody),
- nausea,
- vomit,
- apathy,
- general fatigue, which can turn into excessive drowsiness, and then into a coma and disorders of consciousness or orientation,
- loss of appetite
- diarrhea (watery),
- low blood pressure and low heart rate.
Legionellosis progresses quite quickly. This can lead not only to respiratory failure, but also to dysfunction of other organs, such as the kidneys, heart (heart murmur), or pancreas. The period of development of the disease usually ranges from 2 to 10 days.
How to diagnose legionellosis?
In the case of Pontiac fever, no treatment is required, nor is a medical consultation itself. The symptoms are mild, the disease goes away on its own. However, it is useful to remember to support your immune system so that the immune system works as efficiently as possible, copes better and faster with a possible disease, or so that symptoms simply do not occur.
In a situation where a patient has severe symptoms of legionellosis, including those associated with acute respiratory failure, you should immediately contact a medical facility, such as a hospital emergency department.
It is impossible to make an accurate diagnosis based on physical examination alone. The panel of laboratory tests is always performed from biological material taken from the patient, i.e., blood, urine, or sputum. Unfortunately, none of the currently used laboratory methods is the so-called. A rapid diagnostic test, i.e., you will have to wait at least a few days for the test result. It depends on the necessary time for the cultivation of bacterial rods.
The fastest method is enzyme immunoassay for the presence of L. pneumophila antigens in the patient’s urine. It is assumed that antibodies specific to Legionella pneumophila antigens become detectable from the 7th day after infection. It is important to note that they reach the highest concentration at the 3-4th week. Antibody testing should be done in duplicate, 10 to 14 days apart. This is due to a significant increase in antibody titer, indicating an ongoing legionella infection.
Legionella – treatment
In order to be able to treat the patient, avoiding the above difficulties, use the so-called point scale of clinical symptoms and laboratory tests. Physical symptoms characteristic of Legionnaires’ disease, overall organ performance, and evaluation parameters, e.g., the presence of inflammation in the body.
Treatment of legionellosis most often requires hospitalization and constant outpatient monitoring. The patient is prescribed antibiotics without confirmation of legionella infection, which is caused by a long waiting period for the results of diagnostic studies. The rationale for prescribing antibiotics is due to the fact that the risk of complications caused by the pathogen is reduced. Feeding is also recommended; electrolytes help prevent dehydration and minimize breathing difficulties.
Difficulties arise in the treatment of legionella pneumonia due to the fact that the bacteria of this group produce beta-lactamase. The consequence of this is that they become resistant to penicillins and cephalosporins. The drug of choice here is an antibiotic called erythromycin, which has the ability to penetrate the aforementioned alveolar (lung) macrophages. The possibility of using macrolides (azithromycin) and ketolides (telithromycin), which show more effective activity against legionella strains, is being investigated. It is important to note that these substances penetrate to a greater extent into the lung tissue. Outpatients take oral tetracyclines (e.g., doxycycline, minocline) and macrolides (spiramycin, clarithromycin). In turn, patients whose condition is severe (requiring hospitalization) are treated with intravenous antibiotics – azithromycin or fluoroquinolones. The use of ofloxacin and levofloxacin is a good solution for patients with immunosuppression (induced by a decrease in the body’s immunity) and reduces the length of hospitalization.
Can legionellas be completely cured? Certainly. Many patients make a full recovery. The most dangerous situation arises when we are dealing with the need for hospitalization of the elderly and/or chronically ill.
How can I protect myself from Legionella pneumophila infection?
It should be remembered that legionellas loves rust, so water pipes should be kept clean or replaced periodically. Hot tubs or jacuzzis – this is where regular water changes come in handy. Places such as swimming pools and water-handling devices such as treatment rooms should be subjected to chlorination, ozonation, or other disinfection processes. Hot water systems must maintain temperatures above 60 °C and cold-water systems below 20 °C. Establishments such as hospitals, hotels, schools, resorts should use chlorine dioxide generators.
