the hematology department of the hospital contains a 15-bed conventional unit and a 9-bed protective isolation unit . at the entrances of rooms in the conventional unit , there is a hand hygiene sink ( for staff and visitors ) and a bathroom in a separate area ( shower stall , sink , and toilets ) . in the protective isolation unit , air is filtered through a laminar flow system , and a sink and toilets are located next to each bed ( distance 1.5 m ) . the ceramic sinks have no counter space , and drains are made of stainless steel . all faucets in the department are hand - operated and provided with antibacterial filters ( 0.22 m ) . surfaces are cleaned daily ( once in the conventional unit ) and twice in the protective isolation unit with a solution containing quaternary ammonium compounds ( 0.25% didecyldimethylammonium chloride ) . during 20092016 , a total of 7 patients ( p1p7 ) in the department were infected or colonized by imp-19producing p. aeruginosa , which were isolated from blood samples ( 2 patients ) , urine samples ( 2 patients ) , throat swab samples ( 2 patients ) , and a central venous catheter ( 1 patient ) . all patients underwent throat , urine , and feces sampling at admission and were free of p. aeruginosa , thus indicating nosocomial acquisition . all isolates were resistant to ceftazidime , imipenem , meropenem , doripenem , ciprofloxacin , and most aminoglycosides ; 4 isolates were susceptible to piperacillin and 3 to amikacin . more than 100 environmental samples were obtained when no patients were colonized ( except for samples collected in room 32 a few hours after patient p7 had been transferred to an intensive care unit ) . water samples were collected from different faucets ( nursing room , medication preparation rooms , and rooms of some patients ) . first - catch lukewarm water ( 500 ml ) was collected in sterile bottles containing 20 mg / l sodium thiosulfate and concentrated by filtration ( 0.45-m membrane filters ) . all sinks and shower drains were sampled by rotating a cotton swab inserted through the drain . environmental testing for imp-19 producers in investigation of nosocomial infections linked to contaminated sinks , france . a ) sink ( blue circles ) , swab specimen of sink , and drain ( red circles ) tested . we plated samples from filters ( for water ) and swab specimens ( from sinks ) on drigalski medium containing ceftazidime ( 32 mg / l ) . when a positive culture was observed after 48 hours of incubation , a pcr specific for blaimp-19 was performed for the culture mixture . for samples with a positive pcr result , we then plated a dilution of the culture mixture on drigalski medium containing ceftazidime ( 32 mg / l ) and imipenem ( 16 mg / l ) to obtain isolated colonies , which we further subjected to identification and confirmation of imp-19 production . we used mass spectrometry and nrda gene sequencing to identify for achromobacter isolates ( 6 ) . we used pulsed - field gel electrophoresis after xbai digestion to genotype p. aeruginosa isolates ( 9 ) . pulsotypes were compared by calculating the dice correlation coefficient with dendroupgma software ( http://genomes.urv.cat/upgma/ ) . the 7 clinical isolates belonged to 3 distinct genotypes a , b , and c ( table ; figure 2 ) . we detected environmental imp-19producing isolates belonging to 8 species of gram - negative nonfermenting bacilli : p. aeruginosa , achromobacter xylosoxidans , a. aegrifaciens , p. putida , stenotrophomonas maltophilia , p. mendocina , comamonas testosteroni , and sphingomonas sp . of the 7 environmental isolates of p. aeruginosa we identified , 6 belonged to the same genotype as clinical isolates ( genotype a ) . unweighted pair group method with arithmetic mean cluster analysis of xbai - generated pulsotypes constructed with dice coefficients for the 7 clinical isolates and the 7 environmental isolates of imp-19producing pseudomonas aeruginosa linked to contaminated sinks , france . the blaimp-19 gene was located in various integrons , mainly on a sul - type class 1 integron and a tn402-like class 1 integron . in these integrons , blaimp-19 was associated with different gene cassettes , including aac(6)-ib , aada13 , aadb , or fused qacg - aac(6)-ib ( figure 3 ) . few isolates had several copies of blaimp-19 located on integrons of different structures ( table ) . diversity of integrons harboring blaimp-19 isolated from patients with nosocomial infections linked to contaminated sinks , france . f , sui - type class 1 integrons ; g , tn402like class 1 integron . aac(6)-ib , aminoglycoside 6-n - acetyltransferase ; aada13 , aminoglycoside adenyltransferase ant(3 ) ; aadb , aminoglycoside-2-o - nucleotidyltransferase ; blaimp-19 , metallo--lactamase imp-19 ; fused qacg , aminoglycoside 6-n - acetyltransferase ; intl1 , class 1 integron integrase ; orf5 , open reading frame 5 ; qace1 , multidrug exporter ; sul1 , dihydropteroate synthase ; tniq , transposition protein ; tnir , resolvase . the incidence of mbl producers among imipenem - resistant p. aeruginosa in france is low compared with incidences for other countries ( 2,10 ) . the long intervals without cases , the absence of any overlap between cases , and genotypic diversity of clinical isolates did not suggest a single common source of infection . imp-19 producers were detected in 9 of 15 rooms in the conventional unit and 2 of 9 rooms in the protective isolation unit . these producers were p. aeruginosa and a wide variety of gram - negative nonfermenting bacilli . most of these producers have little clinical relevance , but they are silent reservoirs for dissemination of blaimp-19 to major pathogens . the role of these environmental bacterial species in the spread of mbl suggested in previous studies ( 13,14 ) is confirmed by our findings . the diversity of species found and genetic structures involved with blaimp-19 indicated that the environmental contamination occurred a long time ago . one isolate of imp-19producing aeromonas caviae was found in a patient in the same building in 2006 ( 7 ) . this phenomenon is probably endemic to our hospital , in which sink drains are not accessible for removal of biofilms without complete dismantling ( inappropriate sink design ) . water from faucets is directed straight into the drain , resulting in splashing that can lead to contamination of an area < 1 m from the sink ( 15 ) . therefore , patients can be contaminated when they brush their teeth , wash their hands , or take a shower . healthcare personnel are also at risk for hand contamination , which might lead to transfer of pathogens to patients during care . because the building tested was 16 years old , it has been decided to completely rebuild the ward in early 2017 , paying special attention to water distribution and discharge systems to minimize hospital - acquired infections . in conclusion , our findings might help other hospitals to identify potential reservoirs of carbapenemase - producing bacteria and lead to implementation of rapid control measures to contain outbreaks .
we isolated imp-19producing pseudomonas aeruginosa from 7 patients with nosocomial infections linked to contaminated sinks in france . 
 we showed that blaimp-19 was located on various class 1 integrons among 8 species of gram - negative bacilli detected in sinks : p. aeruginosa , achromobacter xylosoxidans , a. aegrifaciens , p. putida , stenotrophomonas maltophilia , p. mendocina , comamonas testosteroni , and sphingomonas sp .