- Clinical science
Nosocomial infections, also known as hospital-acquired infections, are newly acquired infections that are contracted within a hospital environment. Transmission usually occurs via healthcare workers, patients, hospital equipment, or interventional procedures. The most common sites of infection are the bloodstream, lungs, urinary tract, and surgical wounds. Though any bacteria may cause a nosocomial infection, there is an increasing incidence of multidrug-resistant (MDR) pathogens causing hospital-acquired infections. This rise can be explained by indiscriminate use of antibiotics and lacking hygiene measures, especially among medical staff. Commonly seen multidrug-resistant pathogens include methicillin-resistant Staphylococcus aureus (MRSA), extended-spectrum beta-lactamase-producing bacteria (ESBL), and vancomycin-resistant enterococci (VRE). The choice of antibiotic for treating infections with these pathogens is based on the individual resistance profile and often requires additional strict isolation methods for the patient.
Common causative pathogens
|Type of infection|
|Most common pathogens||Other causative pathogens|
|Surgical site infections|
|Nosocomial pneumonia|| |
|Nosocomial urinary tract infections|
- Age > 70 years
Lengthy hospital stays → high risk of infection
- Via medical staff (e.g., insufficient disinfection of hands, clothing) and contact surfaces (e.g., equipment, furniture)
- Via indoor air (may be contaminated by droplets from infected patients, staff, or procedures like bronchoscopy)
- Metabolic diseases (especially diabetes mellitus) and immunosuppression
- Prior antibiotic use
- Iatrogenic (caused by treatment or a diagnostic procedure)
For an overview of the individual drug resistances and treatment options, see “Treatment of multiresistant pathogens” below.
- Resistance: : developed by forming a modified (PBP) that inhibits binding to beta-lactam antibiotics, thereby decreasing their bactericidal effect
- Occurrence: asymptomatic colonization of the nasal mucosa estimated at 0.5–5% of the population
- Measures to curb MRSA
- Resistance: Bacteria produce beta-lactamases that have a broad spectrum and are thus able to cleave penicillins, cephalosporins, and, in isolated cases, carbapenems.
- Isolation in separate rooms required
- Definition: bacterial strains of the genus Enterococcus that are resistant to the antibiotic vancomycin (e.g., E. faecalis , E. faecium)
- Resistance: acquisition of van genes; → alteration of peptidoglycan synthesis pathway; → inhibits binding of vancomycin to peptidoglycan
- Definition: A pathogen is termed as MDRGN when resistance is demonstrated to at least three antibiotic classes (see “Treatment of multiresistant pathogens” below).
- Hospital hygiene and prevention of infection
- Diseases: pneumonia, severely infected wounds, urinary tract infections, otitis externa ("swimmer's ear"), keratitis
The increased use of antibiotics in hospital settings has led to a greater antibiotic resistance of some bacterial strains. The treatment of infections caused by these strains is difficult since common broad spectrum antibiotics are ineffective and use of alternative drugs is necessary. Therefore, prophylaxis involves both preventing the spread of the causative pathogen as well as treating asymptomatic carriers.
|Pathogen||Resistance||First-line therapy||Alternative therapy|
|Vancomycin-resistant enterococci (VRE)|
|pathogens (Extended-spectrum β-lactamase)|