Ecological effects of selective decontamination on resistant gram-negative bacterial colonization.
BACKGROUND
Selective digestive tract decontamination (SDD) and selective oropharyngeal decontamination (SOD) eradicate gram-negative bacteria (GNB) from the intestinal and respiratory tract in intensive care unit (ICU) patients, but their effect on antibiotic resistance remains controversial.


OBJECTIVE
We quantified the effects of SDD and SOD on bacterial ecology in 13 ICUs that participated in a study, in which SDD, SOD, or standard care was used during consecutive periods of 6 months (de Smet AM, Kluytmans JA, Cooper BS, Mascini EM, Benus RF, van der Werf TS, van der Hoeven JG, Pickkers P, Bogaers-Hofman D, van der Meer NJ, et al. N Engl J Med 2009;360:20-31).


METHODS
Point prevalence surveys of rectal and respiratory samples were performed once monthly in all ICU patients (receiving or not receiving SOD/SDD). Effects of SDD on rectal, and of SDD/SOD on respiratory tract, carriage of GNB were determined by comparing results from consecutive point prevalence surveys during intervention (6 mo for SDD and 12 mo for SDD/SOD) with consecutive point prevalence data in the pre- and postintervention periods.


RESULTS
During SDD, average proportions of patients with intestinal colonization with GNB resistant to either ceftazidime, tobramycin, or ciprofloxacin were 5, 7, and 7%, and increased to 15, 13, and 13% postintervention (P < 0.05). During SDD/SOD resistance levels in the respiratory tract were not more than 6% for all three antibiotics but increased gradually (for ceftazidime; P < 0.05 for trend) during intervention and to levels of 10% or more for all three antibiotics postintervention (P < 0.05).


CONCLUSIONS
SOD and SDD have marked effects on the bacterial ecology in an ICU, with rising ceftazidime resistance prevalence rates in the respiratory tract during intervention and a considerable rebound effect of ceftazidime resistance in the intestinal tract after discontinuation of SDD.
Oostdijk
Evelien A N
EA
Department of Medical Microbiology, University Medical Center Utrecht, GA Utrecht, The Netherlands. E.A.N.Oostdijk@umcutrecht.nl
de Smet
Anne Marie G A
AM
Blok
Hetty E M
HE
Thieme Groen
Emily S
ES
van Asselt
Gerard J
GJ
Benus
Robin F J
RF
Bernards
Sandra A T
SA
Frénay
Ine H M E
IH
Jansz
Arjan R
AR
de Jongh
Bartelt M
BM
Kaan
Jan A
JA
Leverstein-van Hall
Maurine A
MA
Mascini
Ellen M
EM
Pauw
Wouter
W
Sturm
Patrick D J
PD
Thijsen
Steven F T
SF
Kluytmans
Jan A J W
JA
Bonten
Marc J M
MJ
D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D019072:Antibiotic Prophylaxis / Q000009:adverse effects; D002442:Ceftazidime / Q000627:therapeutic use; D002939:Ciprofloxacin / Q000627:therapeutic use; D003428:Cross Infection / Q000188:drug therapy / Q000382:microbiology / Q000517:prevention & control; D024881:Drug Resistance, Bacterial / Q000187:drug effects*; D006090:Gram-Negative Bacteria / Q000187:drug effects*; D016905:Gram-Negative Bacterial Infections / Q000188:drug therapy / Q000382:microbiology / Q000517:prevention & control*; D006801:Humans; D007362:Intensive Care Units; D008137:Longitudinal Studies; D012007:Rectum / Q000382:microbiology; D012137:Respiratory System / Q000382:microbiology; D012141:Respiratory Tract Infections / Q000188:drug therapy / Q000382:microbiology / Q000517:prevention & control*; D014031:Tobramycin / Q000627:therapeutic use
D000900:Anti-Bacterial Agents; D002939:Ciprofloxacin; D002442:Ceftazidime; D014031:Tobramycin