Many scientists and doctors believe that humanity is entering a new era, when antibiotics that save many lives are no longer effective against new strains of microbes. The situation is exacerbated every year largely due to the fact that people abuse drugs and literally grow invulnerable bacteria themselves. Staphylococcus aureus, resistant to methicillin, is just one such deadly monster. "Lenta.ru" writes about the danger of new strains of staphylococci, where they came from and whether they can be defeated.
Hard case
In 2008, a ten-year-old girl was admitted to the pediatric department at Aristotle University (Greece) with a scratch on her right elbow. The child had a high temperature of 40 degrees for the last three days, and she could hardly move her right leg. Doctors diagnosed inflammation of the right hip joint. Suspecting a bacterial infection, the doctors prescribed the antibiotic cloxacillin. Then they did not yet know that they were faced with a deadly adversary.
The girl's condition worsened every hour. Symptoms of brain damage and severe breathing problems due to the penetration of the infection into the lungs appeared. It became clear that cloxacillin was not helping, so several new antibiotics were prescribed at once. On the fifth day, x-rays showed extensive involvement of the right femur and adjacent muscle tissue. The doctors drained the soft tissue in the leg and released pus, which was teeming with methicillin-resistant Staphylococcus aureus (MRSA).
Microbial cultures of Staphylococcus aureus
The girl was in critical condition for a whole week, after which her health began to improve thanks to intensive therapy. However, the infection terrorized the child's body for several months, and the bacteria practically "ate" the bone. It took three years for the body to fully recover from a severe infection. The girl is very lucky because only a small percentage of such cases are successful.
MRSA is commonly associated with nosocomial infections. In other words, patients in hospitals with wounds and weakened immunity are the main risk group. Staphylococcus aureus is able to survive in near sterile conditions and spreads despite disinfection. But, unfortunately, MRSA is also found outside hospitals, in this case it is called household. It was he who was picked up by a ten-year-old patient through an ordinary scratch. Staphylococcus aureus may not cause infection, but if the body is weakened for some reason, the consequences can be catastrophic.
Eating alive
MRSA is one of those “flesh-eating bacteria” that the media tell chilling stories about. This microbe is responsible for a third of all cases of necrotizing fasciitis, a severe infection that literally eats away at the soft tissues of the body. The gateway for a deadly microbe can be a cut or burn, although fasciitis has been known to develop after eating raw seafood. Dental diseases also increase the risk of infection.
However, necrotizing fasciitis can be prevented with proper wound care, hand washing, and good oral hygiene. During treatment, doctors amputate the affected tissue and inject a shock mixture of antibiotics. However, even with proper and timely treatment, a third of patients die.
Lungs affected by staphylococcus
In 2015, doctors reported a highly unusual case of necrotizing fasciitis caused by household staphylococcus aureus. The infection developed with lightning speed in a patient with a normal immune system. A 52-year-old man was admitted to the hospital with unbearable pain in his left hip and swelling that had lasted for a week. Hematomas, blisters were visible on the skin of the leg, and the affected areas lost sensitivity. Despite aggressive therapy, surgical debridement, and broad-spectrum antibiotics, the patient died of sepsis less than 24 hours after treatment. The man did not have any injuries or suspected contact with MRSA, but he was treated for osteoarthritis of the left knee with periodic injections of steroids. The last injection was given three weeks before the onset of symptoms.
MRSA causes more than just soft tissue infections. Staphylococcus, along with necrotizing fasciitis, is capable of provoking fatal necrotizing pneumonia or internal gangrene, which rapidly destroys lung tissue. In most cases, the disease is fatal, even in spite of a loading dose of potent antibiotics directed against staphylococci. Such pneumonia develops more often in children and young adults, especially after a viral respiratory infection, but it also affects older people.
Dangerous species
Nearly 300,000 Staphylococcus aureus-related hospitalizations are reported annually in the United States, with MRSA accounting for almost half. Household staphylococcus aureus differs from nosocomial genetically. In North America, the most common "super infectious" strain USA300.
Resistance to methicillin is conferred by the mecA gene located in the so-called staphylococcal cassette chromosome (SCC), which have different structures in different strains. Household strains have a smaller and less complex version of SCC, which experts refer to as SCC mecA type IVa. It contains fewer genes that contribute to resistance than nosocomial MRSA species, but it includes unique genes for virulence, that is, the ability to cause disease or death of an organism. Thus, household strains are easier to treat, but they kill faster than those that attack patients in hospitals and clinics. Virulence genes produce toxins that are dangerous even to healthy people with normal immunity. One such toxin, Panton Valentine's Leukocidin (PVL), helps bacteria fight off immune cells. The ingestion of PVL-producing MRSA into the human body often leads to soft tissue infections, including necrotizing fasciitis.
Distribution of Staphylococcus aureus in Europe
The USA300 strain arrived in North America in the first half of the 20th century from Europe, where it appeared in the middle of the 19th century. It was then less contagious and did not have many of the mutations that now make it deadly. The bacteriophage ϕSa2USA, which infected the staphylococcus, played a fatal role in the creation of the monster supermicrobe, which carried the gene encoding PVL. At the beginning of the third millennium, the strain became widespread in the United States, and also migrated to South America, Europe, Africa and the Asia-Pacific region. By 2001, the MRSA is believed to have colonized approximately eight percent of the US population.
Fight with the monster
The journalist Sonia Shah in her book "Pandemic: The World History of Deadly Viruses" recalls her meeting with a household MRSA, which her son was infected with: “The pediatrician, usually playful and cheerful, looking at my son's knee, sharply stern. She wrote out the appointment without waiting for the test results: a strong antibiotic clindamycin, good old and reliable bactrim and, in addition, a tough regimen of getting rid of pus with hot compresses and squeezing … Worse still, she hasn't settled on towels, beds, upholstery or free surfaces where she can wait a whole year in the wings."
Staphylococcus aureus
The child recovered, however, despite all efforts and hygiene procedures, the family was not able to completely get rid of the MRSA. Relapse first happened in my son, since staphylococcus settled in his body, sometimes manifesting itself in the form of painful abscesses filled with pus. After a while, the infection spread to the journalist. Shah writes that the chronic infection has subsided by itself, despite all the struggle with the insidious microbes. Nevertheless, in advanced cases, sometimes the only way to stop the infection is to amputate the limbs.
So far, MRSA remains susceptible to a number of antibiotics that do not belong to beta-lactams. However, new strains are being discovered that show resistance to other drugs. The situation is complicated by the fact that antibiotics are used everywhere and often incorrectly, which only provokes the multiplication of bacteria that cause intractable or even incurable infections. At the same time, antibiotics of new classes are invented quite rarely, and, unfortunately, there are no effective substitutes yet.
