Resistance of bacteria to antibiotics is natural and inevitable. By chance a few bacteria are genes that can protect them from drugs, they will pass on these genes – and not only their offspring, but sometimes the neighbors. Experts in computational epidemiology finally get the required data and process them for modeling this phenomenon. But no one is trying to use these tools to predict the end of the era of antibiotics – it has already arrived. They focus on trying to understand how soon, resistant bacteria are in the majority and that the doctor will be able to do with them – if at all possible.
In 2013, the then Director of the Centers for control and prevention (CDC) Tom Frieden told reporters: "If we're not careful, soon we will be postantibioticski era". Today, just four years later, the Agency claims that we proved it. "We say this because universal resistant bacteria have appeared," says Jean Patel [Jean Patel], the leading CDC office of strategy and coordination of the use of antibiotics. "People are dying for lack of antibiotics that can treat their infections, which not so long ago, it was very easy to heal".
Last August, a woman aged 70 came to the hospital in Reno. Nevada, with bacterial infection of the hip. The bacteria belonged to the class of particularly resistant germs, known as the carbapenem-resistant enterobacteria (CRE). But this bacterium would not take any carbapenems, neither tetracyclinenor colistin, and no antibacterial apparatus of 26 commercially available. A few weeks later she died of septic shock.
For officials from health, to which belongs and Patel, this case marks the end of an era and the beginning of a new one. The question is: how quickly this universal resistance can spread? "When we get to a situation in which the infection often cannot be cured, and the pain. says Patel. – It will be very difficult to predict".
She should know, because she's already tried. In 2002 the first staph that is resistant to vancomycin, showed himself in 40-year-old male from Michigan with a chronic ulcer of the leg. The situation seemed very sad: Staphylococcus aureus is one of the most common infections in humans, and vancomycin – the most common antibiotic for its treatment. In addition, a resistance gene was located on the were found – a free-floating ring of DNA that allowed him to move easily. Epidemiologists from the CDC worked together with microbiologists, such as Patel, on the creation of a model predicting how far and how fast it can spread. Patel can't remember the exact numbers, but she recalls that the results were frightening. "We are very much concerned about it," she says.
Fortunately, in this case the model was wrong. In 2002 there were only 13 cases of the appearance of staph that is resistant to vancomycin, and all patients survived.
This error is very puzzling team. But in biology it is sometimes so difficult. "I worked with this bacterium in the laboratory, where it grows well, but from person to person, apparently, does not apply," said Patel. And although they still do not know why, one hypothesis suggests that the emergence of this resistant gene does not pass to the bacteria completely. He made the Staphylococcus aureus immune to his sworn enemy, at the same time complicating the process of survival outside the human body. Hospital rules, time of year, geography can also influence the spread. It's like trying to predict the weather.
"You can't make those predictions on paper, or by careful reflection, says Bruce Lee [Bruce Lee], a researcher of public health Institute of John Hopkins. He works with organizations involved in health care in Chicago and orange County, predicting the most probable path of spread of CRE bacteria of the type that a woman was murdered in Nevada in the case of their appearance in hospitals. In the past such models have been based purely on mathematics – the so-Patel tried to build their predictions. Yes, their equation was difficult, but not enough to take into account things like human behavior, biology of bacteria and their interaction with the environment. "In our region people are increasingly beginning to understand that in order to understand the spread of antibiotic resistant bacteria with a sufficient degree of detail, it is necessary to work with models based on the data in which you can see millions of different scenarios – as do meteorologists," says Lee.
In the study, published last year, it describes the probability distribution of CRE in 28 hospitals and 74 nursing home orange County. In this model, each virtual hospital was written the number of beds matching the number of beds in real institutions, as well as the information about the connectivity of institutions. In the model, each patient was computational unit which on any particular day either tolerate or not tolerate CRE. These units moved on ecosystem health, interacted with doctors, nurses, beds, chairs, doors, a hundred million times, and each new simulation, these parameters are slightly adjusted. He found that without increased control measures, e.g. regular testing patients for resistance and quarantine vectors, CRE will become an endemic disease — constantly present in virtually all the hospitals in orange County in ten years.
But once CRE gets into the health care system, it will be difficult to get rid of. "It's like trying to get rid of house termites, Li says. – As soon as they get where everything is connected with everything, they become intractable part of the ecosystem“. So, if these doctors and nurses can quickly identify people who are able to distribute CRE, he can at least isolate the threat. Even if the patients themselves they have nothing to offer fail.
While the good news is that the only cases of transmission from person to person 100% of resistant bacteria occur only in the supercomputer Lee. In the real world such cases are not recorded. But it is their looking for Patel and CDC. This will bring the situation to the next level, says Patel. To keep abreast, in the past year, the Agency spent $14.4 million on the establishment of a network of seven local laboratories capable of conducting genetic testing bacterial samples taken from hospitals. Now they are implementing a program that someday will be able to link all hospitals in the USA with a tracking system CDC directly to automatically mark each occurred in the U.S. the event associated with antibiotic-resistant bacteria, in real time.
In parallel, Patel, and, with varying degrees of success, the rest of the world, following the development of antibiotics. In this area, too, not everything went smoothly. Last week, the world health organization released a report with analysis of all in the development of antibacterial drugs. The conclusions are grim: not enough medicines, not enough innovation. Every new medicine of the 51 variant is already available in advance it is resistant to microorganisms. Researchers, such as Patel and Lee, I hope that their work allow to minimize existing threats, detect new ones as they emerge, and give pharmaceutical companies time to develop new drugs. The age of antibiotics may have ended – but with the coming of a new era of much more can be done.
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