We examined the carriage of selected resistant bacteria in the stools of healthcare workers who provided direct patient care. Neither vancomycin-resistant enterococci, methicillin-resistant Staphylococcus aureus, nor Clostridium difficile was recovered from the 55 stool specimens collected. A ceftazidime-resistant Citrobacter freundii was isolated from one specimen. We conclude that the stool of healthcare workers is colonized infrequently with these resistant organisms.
Objective To define the epidemiology of broad-spectrum cephalosporin-resistant Gram-negative bacilli in intensive care units (ICUs) during a nonoutbreak period, including the prevalence, the risk factors for colonization, the frequency of acquisition, and the rate of infection. Design Prospective cohort study. Setting Tertiary care hospital. Patients Consecutive patients admitted to two surgical ICUs. Main Outcome Measurements Serial patient surveillance cultures screened for ceftazidime (CAZ) resistance, antibiotic and hospital exposure, and infections. Results Of the 333 patients enrolled, 60 (18%) were colonized with CAZ-resistant Gram-negative bacilli (CAZ-RGN) at admission. Clinical cultures detected CAZ-RGN in only 5% (3/60) of these patients. By using logistic regression, CAZ-RGN colonization was associated with duration of exposure to cefazolin (odds ratio, 10.3; p or=to3 days, 26% acquired a CAZ-RGN. Of the 14 infections caused by CAZ-RGN, 11 (79%) were attributable to the same species present in surveillance cultures at admission to the surgical ICU. Conclusions Colonization with CAZ-RGN was common and was usually not recognized by clinical cultures. Most patients colonized or infected with CAZ-RGN had positive surveillance cultures at the time of admission to the surgical ICU, suggesting that acquisition frequently occurred in other wards and institutions. Patients exposed to first-generation cephalosporins, as well as broad-spectrum cephalosporins/penicillins, were at high risk of colonization with CAZ-RGN. Empirical treatment of nosocomial Gram-negative infections with broad-spectrum cephalosporins, especially in the critically ill patient, should be reconsidered. (Crit Care Med 1999; 27:1090-1095)
VanD-mediated glycopeptide resistance has been reported for an isolate of Enterococcus faecium, BM4339. Three clinical isolates of vancomycin-resistant E. faecium collected from 3 patients during a 6-week period in 1993 had agar dilution MICs of vancomycin and teicoplanin of 128 and 4 μg/mL, respectively. Polymerase chain reaction (PCR) using degenerate primers complementary to genes encoding D-Ala-D-X ligases yielded a 630-bp product that was similar to the published partial sequence of vanD. By use of inverse PCR, vanD, vanHD, and two partial flanking open-reading frames were sequenced. The deduced amino acid sequence of VanD showed 67% identity with VanA and VanB. vanD appeared to be located on the chromosome and was not transferable to other enterococci. The 3 isolates were indistinguishable by pulsed-field gel electrophoresis and differed from BM4339. No other isolates carrying vanD were found in a subset of 875 recent US isolates of vancomycin-resistant enterococci.
The utility of peptide nucleic acid fluorescence in situ hybridization (PNA FISH) for the detection of Acinetobacter spp. and Pseudomonas aeruginosa was evaluated on broth suspensions and spiked blood cultures of ATCC strains and clinical isolates with select gram-negative rods. After testing 60 clinical isolates, PNA FISH had a sensitivity and specificity of 100% and 100%, respectively, for Acinetobacter spp. and 100% and 95%, respectively, for P. aeruginosa. PNA FISH was able to detect both pathogens simultaneously and directly from spiked blood cultures.
ObjectivesThe G2576T mutation in domain V of 23S rRNA has been most often associated with the rare cases of linezolid resistance in Staphylococcus aureus. In a linezolid-susceptible S. aureus (A8761B) possessing a single mutated (G2576T) copy, originally derived from a resistant clinical isolate, we assessed the persistence of the mutation on further passage on antibiotic-free medium and the selection of resistance upon re-exposure of the susceptible strain to linezolid.
ABSTRACT We described the molecular epidemiology of expanded-spectrum cephalosporin-resistant gram-negative bacilli (RGN) recovered from inanimate surfaces. RGN were isolated from 9% of environmental cultures. Numerous species, each with multiple unique strains, were recovered. Epidemiological links between environmental, personnel, and patient strains suggested the exogenous acquisition of RGN from the hospital environment.
