Identification of human-dependent routes of pathogen's transmission in a tertiary care hospital

The purpose of the study was to validate the risk of patients' exposure to pathogenic flora carried on hands of students, visitors, and patients themselves, analyzing its density and genera and to compare them with the microflora of healthcare workers (HCWs).

Between May and June 2018, five groups of participants were included. Each group consisted of eight individuals. Palmar skin imprints were obtained from dominant hands of doctors, nurses, students, visitors, and patients in orthopedics ward. Imprints were incubated at 37°C under aerobic conditions, and colony-forming units (CFU) on each plate were counted after 24, 48, and 72 h. Microorganisms were identified.

Hands of doctors were colonized more often by Gram - positive non-spore-forming rods bacteria than hands of nurses (p<0.05). A higher number of Staphylococcus epidermidis CFUs was observed on doctors' than on nurses' hands (p<0.05), whereas Staphylococcus hominis was isolated from doctor's and patients' imprints, but was not from nurses' and students' imprints (p<0.05). Micrococcus luteus colonized patients' hands more often than students' (p<0.05), visitors' hands than doctors' (p<0.05), students' than nurses' (p<0.05), visitors' than nurses' (p<0.05) and patients' hands (p<0.05). Staphylococcus aureus (S. aureus) was isolated only from one doctor and one nurse (203 and 10 CFUs/25 cm² ). Imprints taken from the hands of patients, students and visitors were S. aureus-free. No methicillin-resistant S. aureus (MRSA), vancomycin-resistant enterococci, nor expanded spectrum betalactamase-positive or carbapenemase-positive rods were isolated. The number of Gram-negative rods was the highest on visitors' hands, significantly differing from the number on patient's, doctor's, nurse's, and student's hands. Spore-forming rods from genus of Bacillus were isolated from representatives of all tested groups. Bacillus cereus occurred more commonly on visitors' hands than doctors' hands (p<0.05).

Patients, students, and visitors may play the causal role in the spread of pathogenic bacteria, particularly spore-forming rods. Our study results confirm the effectiveness of educational activities, that is the hospital's hand hygiene program among HCWs, patients, and visitors. Hand hygiene procedures should be reviewed to put much more effort into reducing the impact of all studied groups on the transmission of infectious diseases.