Bacterial infection how is it transmitted

Active carriers have completely recovered from a disease and harbor the organism indefinitely. Salmonella , especially Salmonella Typhi, the cause of typhoid fever, is an example of a bacterial infection that can produce a prolonged carrier state without the individual being aware of the condition. Salmonella can lurk in a quiescent state in organs such as the gallbladder, sometimes even permanently.

These individuals may continuously transfer the pathogen to their contacts. Mary Mallon, a New York City cook in the early s, known as Typhoid Mary, was a carrier responsible for many cases of typhoid fever. Infections acquired from animal reservoirs are referred to as zoonoses or zoonotic diseases.

Humans acquire infection from animals either by direct contact, as in the case of pets or farm animals, by ingestion of the animal or inhalation of bacteria in or around its hide, or through an insect vector that transmits the pathogen from the animal to the human via a bite. Diarrhea caused by Salmonella can occur after handling turtles and contaminating one's hands with their feces, or from ingesting undercooked chicken contaminated with the bacteria, or through other routes such as eating undercooked or raw chicken eggs.

The disease tularemia, caused by the organism Francisella tularensis , is often seen in individuals who have recently skinned a rabbit. Similarly, anthrax caused by Bacillus anthracis follows either inhalation of spores from dead animals or hides, or entry of spores into a wound. In Lyme disease, the deer tick transmits the spirochete Borrelia from the white-footed mouse to the human. Overflow is a phenomenon particularly relevant to zoonotic diseases. Using the example of Lyme disease, the cycle of transmission between tick hosts and animal hosts such as deer and mice leads to the presence of infected ticks that can also infect humans.

Thus the cycle allows the Lyme organisms to overflow from the natural cycle of infection into humans. Reducing the number of infected deer on a New England island through culling, for example, has been shown to greatly decrease the number of infected ticks and almost eliminate infection in humans. Arthropods reservoirs include insects and arachnids.

A vector is commonly understood to be an arthropod that is involved in the transmission of disease. Common insect vectors for bacterial infection include fleas, lice, and flies. Arachnid vectors include mites and ticks.

The diseases caused by the bacteria Borrelia which include relapsing fever and the disease referred to in the Unites States as Lyme disease after it was discovered in Lyme, Connecticut infects ticks that take a blood meal from an infected deer or mouse. These ticks see Figure 3 then inject the bacteria into a human some time later during another blood meal. Other bacterial diseases caused by arthropods include epidemic, murine, and scrub typhus, caused by Rickettsia carried by lice, fleas, and mites, respectively, Rocky Mountain spotted fever also caused by Rickettsia and carried by ticks, and bubonic plague carried by fleas.

Amanda Loffis, Dr. William Nicholson, Dr. Will Reeves, Dr. Chris Paddock. Air can become contaminated by dust or human respiratory secretions containing pathogenic bacteria.

Bacteria do not multiply in the air itself, but may be transported by air currents to areas more conducive to their growth. Infections acquired through the air are characterized as airborne. The classic airborne bacterial infection is tuberculosis. Soil is typically a reservoir for bacteria that form spores when not in a host. The various species of Clostridium can be acquired from exposure of a wound to dirt or soil.

These anaerobic bacteria cause tetanus, botulism, and gas gangrene. Anthrax spores can survive for as long as years in soil. Heavy rain, excavation, and tilling may bring them to the surface and cause an outbreak of anthrax among livestock. In medieval Europe, specific pasturelands were avoided for domesticated animal grazing because of the risk of anthrax.

Food, including milk, when not handled properly, can be the reservoir for a wide variety of pathogenic organisms. Food may be contaminated by feces, or the animal itself may be infected, such as in the case of chickens with Campylobacter or Salmonella. Food can also be contaminated with the ubiquitous spores of Botulinum , which can cause a form of paralysis called botulism. Pasteurization and food sterilization are important public health safeguards against these infections.

Food handlers can carry a variety of bacteria on their hands, and indeed there are stringent regulations in many countries regulating food handling and handlers.

Seafood can be contaminated from bacteria in the water. Soft cheeses are common reservoirs for Listeria monocytogenes. Sometimes, unexpected foods become reservoirs for bacterial infection, as in the case of alfalfa and other raw seed sprouts, which since the s were known to be reservoirs for both Salmonella and Escherichia coli. It is thought that the presoaking and germination of the seeds in nutrient solutions is conducive to the growth and multiplication of these pathogenic bacteria.

The seeds themselves can become contaminated at any point in their production and distribution. Transmission via these uncooked foodstuffs has been documented to cause the majority of foodborne bacterial outbreaks in some locations. Water generally becomes a reservoir for infection when it is contaminated by soil microbes, or animal or human feces. Raw sewage may contaminate drinking water during a storm or flood when sewage systems are overwhelmed, or if it is inadequately treated and dumped into local waters see Figure 4.

There is also concern about the potential for terrorists to use water as a reservoir for bioterrorism pathogens. Sources of water contamination.

Baltimore: Lippincott Williams and Wilkins. Many inanimate objects are considered fomites, as they are capable of indirectly transmitting infection from one person to another by acting as an intermediate point in the cycle of transmission.

Fomites commonly found in households that allow transmission of infection between family members include doorknobs, toilet seats, and utensils. At daycare centers and pediatrician's offices, infection is transmitted via toys handled by children with contaminated hands. In hospitals, there are countless fomites capable of spreading infection. Many respiratory infections are not spread through aerosols, but rather through respiratory secretions saliva, sputum, etc. There are five principal modes by which bacterial infections may be transmitted: Contact, airborne, droplet, vectors, and vehicular contaminated inanimate objects such as food, water, and fomites see Figure 5.

Modes of disease transmission. Transmission via contact includes direct skin-to-skin or mucous membrane-to-mucous membrane contact or fecal—oral transmission of intestinal bacteria. Transfusion of contaminated blood products also transmits several bacterial infections, such as syphilis.

Some bacteria are carried on air currents in droplet nuclei. Q fever, tuberculosis, and Legionella travel great distances from their origin. Animals with Q fever have been known to transmit infection to other animals as far as 10 miles away. They are generally more susceptible than airborne droplet nuclei to filtering in the nose via nasal hairs or to removal by nasal or facial masks. Typically, the arthropod mosquito, tick, louse takes a blood meal from an infected host which can be human or animal and transfers pathogens to an uninfected individual.

Bacteria such as Shigella can adhere to the foot pad of house flies and be transmitted in this manner. Bacterial infection due to food and water generally develops when bacteria enter the intestine via the mouth.

Those organisms that survive the low pH of the stomach and are not swept away by the mucus of the small intestine adhere to the cell surfaces. There they may invade the host cells or release toxins, causing diarrhea.

Infection acquired from fomites is usually the result of the organism attaching to the host's skin generally on their hand when they come in contact with a contaminated object, and then being deposited onto a mucus membrane when the host touches his or her face, or in some cases his or her genitals, with the contaminated body part Table 2.

Among the top causes of mortality in the world, lower respiratory infection is the third most common and diarrhea is the sixth. Both are often caused by bacteria. Tuberculosis is the seventh most common cause of death. Clearly, measures to prevent infection have a dramatic impact on morbidity and mortality.

Prevention is especially important in this age of increasing antibiotic resistance, because treatment can be so difficult to achieve. There are three major principals of control of bacterial infection: Eliminate or contain the source of infection, interrupt the chain of transmission, and protect the host against infection or disease.

In addition, there is increasing recognition that elimination of important cofactors, such as air pollution from vehicles or from indoor cooking, can markedly reduce the incidence of bacterial infections. Which measure is most effective often depends on the reservoir for the infection. Prevention of infection, e. Animals transmit disease in various ways. Some exposures, such as anthrax from animal hides, may be occupational, others, such as Campylobacter or Yersinia , result from contamination of food or water by animal feces.

Measures to prevent infection include the use of personal protective equipment when handling animals, animal vaccinations such as for anthrax or brucellosis , use of pesticides to prevent transmission from animal to human by insect bite, isolation or destruction of diseased animals, and proper disposal of animal waste and carcasses. For control of plague, rat populations can be suppressed by the use of poisons as well as improved sanitation.

Infections acquired from insect vectors can be minimized by the use of window screens, insect repellent, and protective clothing. Checking the body including pets for ticks at the end of each day can prevent transmission of tickborne bacterial infections, as most require a sufficient period of time after attachment to transmit infection. Improperly treated water can lead to outbreaks of typhoid, Escherichia coli , or Shigella as well as viral and parasitic diseases.

Improvement of the water supply in developed areas has been instrumental in decreasing the burden of infection in communities. Most antibiotics work against more than one type of bacteria, but not against them all. There are different ways that you can take antibiotics. You can take them by mouth, topically on the surface of the skin or eye , or through intravenous therapy IV. If you're using a prescription antibiotic, make sure you use it as directed. For example, don't use a skin antibiotic on your eyes.

It's important to take your medication exactly as prescribed and for the complete duration of your prescription.

Your doctor might prescribe pain medicine or anti-inflammatory medication. These medications can help ease the pain and swelling from your bacterial infection. If you have a fever, your doctor may also recommend fever-reducing medication. If you have a painful cough, your doctor may suggest anti-cough medication. And you may need IV fluids if you're becoming dehydrated. If you have an abscess, you may need to have surgery to treat it.

This can be a simple procedure for a superficial abscess in the skin. But an abscess located deep in the body—like in the brain or intestines—may require a more extensive surgery to remove it.

Bacterial infections are incredibly common and are also quite different from one to another. The type of bacteria involved, its cause, location, and timing all influence the course of your infection. Even symptoms vary a great deal. Some infections can worsen and cause severe complications. Even diagnosis and treatment options depend on the specific infection you may have. You're likely going to have at least a few bacterial infections throughout your life. These infections can cause a range of symptoms and effects.

Your doctor can use diagnostic testing to determine which specific infection you have. Sometimes, you may need prescription medicine, such as antibiotics, to treat your condition. Using an antibiotic "just in case" you have a bacterial infection is never a good idea. Reusing an old prescription is also not recommended. Your infection could get worse from taking the wrong medicine. And you could develop bacterial resistance if you use antibiotics unnecessarily. If you think you have a bacterial infection that needs treatment, talk to your doctor.

Looking to avoid getting the flu? Our free guide has everything you need to stay healthy this season. Sign up and get yours today. Acute bacterial prostatitis: diagnosis and management. Am Fam Physician.

Persistent bacterial infections, antibiotic tolerance, and the oxidative stress response. Clinical and pathophysiological overview of acinetobacter infections: a century of challenges.

Clin Microbiol Rev. Combination of white blood cell count and left shift level real-timely reflects a course of bacterial infection. J Clin Lab Anal. Bacterial, fungal, and parasitic infections of the central nervous system: radiologic-pathologic correlation and historical perspectives. Overview of systematic reviews assessing the evidence for shorter versus longer duration antibiotic treatment for bacterial infections in secondary care.

McCullers JA. The co-pathogenesis of influenza viruses with bacteria in the lung. Nat Rev Microbiol. Your email: is required Error: This is required Error: Not a valid value.

Send to: is required Error: This is required Error: Not a valid value. On this page What are bacterial infections? What are the symptoms of a bacterial infection? What causes bacterial infections? When should I see my doctor? What are the complications of bacterial infections? How are bacterial infections treated? How can bacterial infections be prevented? Resources and support Related information on Australian websites What are bacterial infections?

There are some general signs of bacterial infection: fever feeling tired or fatigued swollen lymph nodes in the neck, armpits, groin or elsewhere headache nausea or vomiting What causes bacterial infections? Signs that you may have a bacterial infection and should see doctor include: difficulty breathing a persistent cough , or coughing up pus unexplained redness or swelling of the skin a persistent fever frequent vomiting and trouble holding liquids down blood in urine , vomit or poo stool severe stomach pain or severe headache a cut or burn that is red or has pus What are the complications of bacterial infections?

Seek immediate medical attention if you have any of the following: fever chills uncontrolled shaking rapid breathing and heart rate tiredness headaches How are bacterial infections treated? Resources and support If you think you may have a bacterial infection, use healthdirect's online Symptom Checker. Back To Top.

General search results. Learn when antibiotics are really needed - for infections caused by bacteria, not viruses. Bacteria is a term to describe a group of cells. Why and when to get tested for MRSA. Healthdirect 24hr 7 days a week hotline 24 hour health advice you can count on An infection occurs when germs enter the body, increase in number, and cause a reaction of the body. A Source is an infectious agent or germ and refers to a virus, bacteria, or other microbe.

In healthcare settings, germs are found in many places. People are one source of germs including:. People can be sick with symptoms of an infection or colonized with germs not have symptoms of an infection but able to pass the germs to others.

Germs are also found in the healthcare environment. Examples of environmental sources of germs include:. A susceptible person is someone who is not vaccinated or otherwise immune, or a person with a weakened immune system who has a way for the germs to enter the body.

Devices like IV catheters and surgical incisions can provide an entryway, whereas a healthy immune system helps fight infection. When patients are sick and receive medical treatment in healthcare facilities, the following factors can increase their susceptibility to infection.