Carbapenem-resistant Enterobacteriaceae (CRE) are emerging extremely drug-resistant pathogens; blaKPC is the predominant carbapenemase in Israel. Early detection of asymptomatic rectal carriers is important for infection control purposes. We aimed to determine who among newly identified CRE rectal carriers is prone to have a subsequent clinical specimen with CRE. A matched case-control study was conducted in a tertiary care teaching hospital in Israel. Cases with a primary positive CRE rectal test and subsequent CRE clinical specimens were matched in a 1:2 ratio with CRE rectal carriers who did not develop subsequent CRE clinical specimens (controls). Matching was based on calendar time of primary CRE isolation, whether the primary CRE isolation was ≤ 48 h or > 48 h after hospital admission, and time at risk to have a subsequent clinical specimen. Data were extracted from the patients' medical records and from the hospital's computerized database. One hundred and thirty-two newly identified CRE rectal carriers (44 cases, 88 controls) were included. The median time interval between screening and subsequent clinical specimens was 11 days (range, 3-27); 86% of the clinical specimens were classified as true infections. Independent predictors of subsequent CRE clinical specimens were: admission to the intensive care unit, having a central venous catheter, receipt of antibiotics, and diabetes mellitus. Identification of the risk factors for subsequent infections among CRE-colonized patients can be used to control modifiable risk factors and to direct empirical antimicrobial therapy when necessary.

Together with the information available in the MLST database, our results suggest that, like Escherichia coli and Klebsiella pneumoniae, E. cloacae harbours clonal lineages of increased epidemic potential that may be associated with resistance spread.

Prior fluoroquinolone use, transfer from another healthcare facility, and admission less than or equal to 3 months since the first CRE isolation are predictors of persistent CRE rectal carriage. These predictors can be used in designing CRE prevention strategies.

The prospective project MOSAR was conducted in five rehabilitation units: the Berck Maritime Hôpital (Berck, France), Fondazione Santa Lucia (Rome, Italy), Guttmann Institute (GI; Barcelona, Spain), and Loewenstein Hospital and Tel-Aviv Souraski Medical Center (TA) (Tel-Aviv, Israel). Patients were screened for carriage of Enterobacteriaceae resistant to expanded-spectrum cephalosporins (ESCs) from admission until discharge. The aim of this study was to characterize the clonal structure, extendedspectrum ␤-lactamases (ESBLs), and acquired AmpC-like cephalosporinases in the Escherichia coli populations collected. A total of 376 isolates were randomly selected. The overall number of sequence types (STs) was 76, including 7 STs that grouped at least 10 isolates from at least three centers each, namely, STs 10, 38, 69, 131, 405, 410, and 648. These clones comprised 65.2% of all isolates, and ST131 alone comprised 41.2%. Of 54 STs observed only in one center, some STs played a locally significant role, like ST156 and ST393 in GI or ST372 and ST398 in TA. Among 16 new STs, five arose from evolution within the ST10 and ST131 clonal complexes. ESBLs and AmpCs accounted for 94.7% and 5.6% of the ESC-hydrolyzing ␤-lactamases, respectively, being dominated by the CTX-M-like enzymes (79.9%), followed by the SHV (13.5%) and CMY-2 (5.3%) types. CTX-M-15 was the most prevalent ␤-lactamase overall (40.6%); other ubiquitous enzymes were CTX-M-14 and CMY-2. Almost none of the common clones correlated strictly with one ␤-lactamase; although 58.7% of ST131 isolates produced CTX-M-15, the clone also expressed nine other enzymes. A number of clone variants with specific pulsed-field gel electrophoresis and ESBL types were spread in some locales, potentially representing newly emerging E. coli epidemic strains.

Extended-spectrum b-lactamaseIncidence rate Machine learning a b s t r a c t Objectives: The aim of the study was to measure the impact of antibiotic exposure on the acquisition of colonization with extended-spectrum b-lactamase-producing Gram-negative bacteria (ESBL-GNB) accounting for individual-and group-level confounding using machine-learning methods. Methods: Patients hospitalized between September 2010 and June 2013 at six medical and six surgical wards in Italy, Serbia and Romania were screened for ESBL-GNB at hospital admission, discharge, antibiotic start, and after 3, 7, 15 and 30 days. Primary outcomes were the incidence rate and predictive factors of new ESBL-GNB colonization. Random forest algorithm was used to rank antibiotics according to the risk of selection of ESBL-GNB colonization in patients not colonized before starting antibiotics. Results: We screened 10 034 patients collecting 28 322 rectal swab samples. New ESBL-GNB colonization incidence with and without antibiotic treatment was 22/1000 and 9/1000 exposure-days, respectively. In the adjusted regression analyses, antibiotic exposure (hazard ratio (HR) 2.38; 95% CI 1.29e4.40), age 60 e69 years (HR 1.19; 95% CI 1.05e1.34), and spring season (HR 1.25; 95% CI 1.14e1.38) were independently associated with new colonization. Monotherapy ranked higher als combination therapy in promoting ESBL-GNB colonization. Among monotherapy, cephalosporins ranked first followed by tetracycline (second), macrolide (fourth) and cotrimoxazole (seventh). Overall the ranking of cephalosporins was lower when used in combination. Among combinations not including cephalosporins, quinolones plus carbapenems ranked highest (eighth). Among sequential therapies, quinolones ranked highest (tenth) when prescribed within 30 days of therapy with cephalosporins. Conclusions: Impact of antibiotics on selecting ESBL-GNB at intestinal level varies if used in monotherapy or combination and according to previous antibiotic exposure. These finding should be explored in future clinical trials on antibiotic stewardship interventions.