From the Guidelines
The gut plays a crucial role as a reservoir for microorganisms, and its disruption can lead to infections, emphasizing the need for strategies to prevent colonization and maintain a healthy microbiome. The gut microbiome is a complex ecosystem that, when balanced, provides colonization resistance against pathogenic microorganisms, thereby preventing infections. However, when this balance is disrupted, harmful bacteria can overgrow and cause local or systemic infections.
To prevent colonization by harmful organisms, several strategies can be implemented:
- Selective digestive decontamination (SDD) using antibiotics like polymyxin E, tobramycin, and amphotericin B can be effective in high-risk patients, particularly those in intensive care 1.
- Probiotics containing Lactobacillus and Bifidobacterium species can help maintain a healthy microbiome, typically dosed at 10-20 billion CFU daily 1.
- Fecal microbiota transplantation (FMT) has shown remarkable success in treating recurrent Clostridioides difficile infections, with cure rates exceeding 90% 1.
- For established colonization, targeted antibiotic therapy based on susceptibility testing is essential, such as vancomycin (125 mg four times daily for 10-14 days) for C. difficile or carbapenem antibiotics for resistant gram-negative infections 1.
- Maintaining good hand hygiene, implementing contact precautions, and antibiotic stewardship are crucial preventive measures.
The transition from colonization to infection can be facilitated by various risk factors, including recent exposure to antibiotics, hospitalization, and underlying health conditions. Therefore, it is essential to identify these risk factors and implement preventive strategies to minimize the risk of infection.
In the context of intra-abdominal infections, the choice of empiric antibiotic regimens should be based on the clinical condition of the patients, the individual risk for infection by resistant pathogens, and the local resistance epidemiology 1. The use of broad-spectrum antibiotics should be limited to preserve their activity, and alternative options such as ceftolozone/tazobactam and ceftazidime/avibactam can be considered for treating infections caused by multidrug-resistant gram-negative bacteria.
Overall, maintaining a healthy gut microbiome through preventive strategies and appropriate antibiotic use is crucial for preventing infections and promoting overall health. The most effective approach to preventing colonization and infection is a multifaceted one, incorporating SDD, probiotics, FMT, targeted antibiotic therapy, and good hygiene practices.
From the Research
Role of the Gut as a Reservoir
- The gut microbiota plays a crucial role in preventing invading microbes from colonizing the gastrointestinal tract, a phenomenon known as colonization resistance 2.
- The human gastrointestinal tract hosts a diverse network of microorganisms, collectively known as the microbiota, which influences various aspects of human health 3.
- The gut microbiota acts as a pivotal mediator in establishing a harmonious mutualistic symbiosis with the host and shielding the host against pathogens 4.
Risk Factors for Colonization
- Perturbations to the microbiota, such as antibiotic administration, can alter microbial composition and result in the loss of colonization resistance 2.
- Antibiotic use can disrupt the intestinal microbiota, increasing the risk of colonization by intestinal pathogens 5.
- The use of oral antibiotics, such as ampicillin, vancomycin, metronidazole, and neomycin, can have long-term negative effects on the intestinal microbiota and promote the development of antibiotic-resistant bacterial strains 5.
Transition from Colonization to Infection
- Dysbiosis of the microbial community can lead to enteric infections 4.
- The transition from colonization to infection can occur when the balance of the gut microbiota is disrupted, allowing pathogens to overgrow and cause infection 2.
- Restoring the balance of the gut microbiota through fecal microbiota transplantation or standardized microbiome restoration therapies can help prevent and treat infections, such as recurrent Clostridioides difficile infection 6.