Antibiotic usage and risk of colonization and infection with antibiotic-resistant bacteria: a hospital population-based study.
Accurate assessment of risk factors for nosocomial acquisition of colonization by antibiotic-resistant bacteria (ARB) is often confounded by scarce data on antibiotic use. A 12-month, nested, multicenter cohort study was conducted. Target ARB were methicillin (meticillin)-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), and ciprofloxacin-resistant Pseudomonas aeruginosa (CR-PA). Nares and rectal swabs were obtained before and after starting antibiotics. Pulsed-field gel electrophoresis was done to define genetic relatedness of the strains. Primary outcomes were (i) the mean time, in days, for acquisition of target ARB colonization in patients previously not colonized; (ii) the rate of acquisition per 1,000 antibiotic-days according to different classes of antibiotics; (iii) the rate of infection caused by the same bacteria as those previously isolated in screening samples; and (iv) the risk factors for ARB acquisition. In total, 6,245 swabs from 864 inpatients were processed. The rate of acquisition was 3%, 2%, and 1% for MRSA, VRE, and CR-PA, respectively. The rate of acquisition of ARB per 1,000 antibiotic-days was 14 for carbapenems, 9 for glycopeptides, and 6 for broad-spectrum cephalosporins and quinolones. The highest rates of acquisition were observed for carbapenems in dialyzed and diabetic patients. Four risk factors were independently associated with acquisition of target ARB: use of carbapenems, age of >70 years, hospitalization for >16 days, and human immunodeficiency virus infection. During the 30-day follow-up, 4 among 42 patients newly colonized by ARB (9%) suffered from an infection due to the same bacteria as those isolated in a previous screening sample. Colonizing and infecting strains from single patients were genotypically identical. Identifying ARB colonization early during antibiotic therapy could target a high-risk hospitalized population that may benefit from intervention to decrease the risk of subsequent nosocomial infections.
Tacconelli
Evelina
E
Department of Infectious Diseases, Università Cattolica del Sacro Cuore, Rome, Italy. etacconelli@rm.unicatt.it
De Angelis
Giulia
G
Cataldo
Maria Adriana
MA
Mantengoli
Elisabetta
E
Spanu
Teresa
T
Pan
Angelo
A
Corti
Giampaolo
G
Radice
Anna
A
Stolzuoli
Lucia
L
Antinori
Spinello
S
Paradisi
Franco
F
Carosi
Giampiero
G
Bernabei
Roberto
R
Antonelli
Massimo
M
Fadda
Giovanni
G
Rossolini
Gian Maria
GM
Cauda
Roberto
R
D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use*; D001424:Bacterial Infections / Q000188:drug therapy* / Q000453:epidemiology* / Q000382:microbiology; D015780:Carbapenems / Q000627:therapeutic use; D002939:Ciprofloxacin / Q000627:therapeutic use; D015331:Cohort Studies; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D016983:Enterococcus / Q000187:drug effects / Q000472:pathogenicity; D005260:Female; D006761:Hospitals / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects / Q000472:pathogenicity; D008875:Middle Aged; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000472:pathogenicity; D020713:Vancomycin Resistance
D000900:Anti-Bacterial Agents; D015780:Carbapenems; D002939:Ciprofloxacin