Κλινικοεργαστηριακή διερεύνηση της φορείας και των λοιμώξεων από πολυανθεκτικά στελέχη σε ασθενείς της μονάδας εντατικής θεραπείας και των μονάδων αυξημένης φροντίδας

Abstract

The purpose of this study was to investigate the colonization and infectionscaused by KPC-producing Klebsiella pneumoniae (KPC-Kp), vancomycin-resistantEnterococcus (VRE) and methicillin-resistant Staphylococcus aureus in patientshospitalized in the Intensive Care Units of the University Hospital of Patras (ICU A)and the General Hospital “Saint Andrew” during October 2009 and February 2012.The dissemination of KPC-Kp constitutes the most important issue in GreekICUs, with its percentage rising in medical and surgical wards. During the duration ofthis study, 12.8% of patients admitted in the ICU A (52 from 405 patients) werecolonized upon admission and previous ICU stay, chronic obstructive pulmonarydisease, duration of previous hospitalization and previous usage of carbapenem orcombination of beta-lactamic/lactamase were found to influence colonization. Agradual increase of the percentage of colonized patients admitted at the ICU from3.9% (4 from 102 patients) during the first 6 months to 15.8% (48 from 300 patients)the next 16 months that reflects the dissemination of KPC-Kp in non-ICU wards.Among the 226 non-colonized upon ICU A admission patients, 164 (72.6%)became colonized during their stay with the presence of colonized patients in nearbybeds and the previous colonized occupant in the same bed were associated withcolonization, which did not influence mortality. The high percentage of colonizationin combination with the aforementioned factors indicates the importance of thedissemination of KPC-Kp among patients via the personnel and signifies the value ofa strict implementation of infection control protocols.In total, 53 patients developed KPC-Kp bloodstream infection during ICU Astay with 43.4% mortality. The most important factors that influence mortality werethe resistance of the strain to gentamicin/colistin/tigecycline and septic shock, whilethe treatment with two active antibiotics was associated with better survivalconfirming the results of previous studies favoring combination therapy for thetreatment of KPC-Kp infection.The development of resistance against colistin or tigecycline, which areconsidered the last frontier in the treatment of KPC-Kp infections, is an alarmingphenomenon. In total, 24.4% and 17.9% of ICU A patients became colonized byKPC-Kp resistant to colictin or tigecycline, respectively. As expected, the administration of colistin or tigecycline influenced colonization, while the mostimportant factor favoring colonization was the presence of colonized patients innearby patients, indicating the importance of dissemination of these strains against denovo resistance development.The comparison of the two ICUs, found a higher percentage of patientscolonized during ICU A stay (61.8% vs 34.1%) and in a shorter period (10.6 vs 19.9days). These results may be explained by the higher percentage of patients colonizedupon admission (11.4% vs 1.8%), the lower nurse/patient ration and the highercarbapenem administration.In total, 305 and 100 strains of K. pneumoniae isolated from patientshospitalized in ICU A and B, respectively, were positive for the presence of blaKPCgene while five strains in ICU A were positive for the blaVIM gene also. All strainswere resistant to penicillins, cephalosporins, aztreonam, trimethoprimsulfamethoxazole (30% of ICU B strains were sensitive), amikacin, tombramycin andquinolones. The resistance rates to carbapenems (67.9% vs 60%), colisitn (35.1% vs18%), gentamicin (50.8% vs 24%) and tigecycline (17% vs 18%) among the ICUsstrains were comparable. PFGE of 57 and 20 isolates from ICU A and B, respectively,revealed that ICU A strains belonged in two types, with type A comprising 65.5% ofthe isolates, while all ICU B isolates belonged in type A.The percentage of VRE colonization in both ICUs were lower in comparisonwith those of KPC-Kp. During ICU admission 14.3% (71 from 497 patients) wasalready colonized, while 14.4% (36 from 250 patients) became colonized during stay.The most important factor influencing colonization was the presence of colonizedpatients in nearby beds, indicating that non adherence with hand hygiene may play apredominate role in VRE dissemination.In total 107 VRE strains were isolated (100 E. faecium and 7 E. faecalis).Eighty four were positive for the vanA gene and resistant to vancomycin andteicoplanin, while the rest were vanB positive and were characterized by low levelresistance to vancomycin (12 were in susceptibility range) and susceptible toteicoplanin. All strains were susceptible to linezolid, daptomycin and tigecycline. AsMLST revealed, E. faecium strains belonged in six different Sequencing Types(ST117, ST17, ST203, ST226, ST786, ST125) with 90% among them belonging tothe Clonal Complex CC17. E. faecalis strains were categorized in four STs (ST6,ST41, ST19, ST28). The proportion of colonized patients by MRSA upon admission and duringICU stay was very low (5.3% and 3.7%, respectively). The most important factorassociated with colonization was enteric carriage of vanA-positive Enterococcus.Surveillance cultures revealed 28 mecA-positive S. aureus strains, with the majority(n=19) being PVL-positive, belonging to ST80 and resistant only to kanamycin,tetracycline and fucidic acid, while the remaining were categorized in four STs (6strains in ST239 and one at ST225, ST72 and ST30). The ST30 strain was tstpositive.The comparison of colonization strains from patients (n=67) and personnel(n=23) of the ICUs (Group A) with the strains of colonization (n=53) and bloodstreaminfections (n=75) isolated from non-ICU patients (Group B), revealed a higherpercentage of MRSA and PVL-positive strains in Group B, while Group A wascharacterized by higher percentage of tst-positive strains indicating their silentdissemination between ICU patients and personnel.The present study has identified the risk factors for colonization of infectionby KPC-Kp, VRE and MRSA, in order to guide the future efforts towards containingtheir dissemination in the two ICUs, as well as, to the Greek hospitals, which in totalare plagued by the aforementioned pathogens.