Outbreak of extended-spectrum ß-lactamase-producing Klebsiella oxytoca infections associated with contaminated handwashing sinks(1).

Klebsiella oxytoca is primarily a health care-associated pathogen acquired from environmental sources. During October 2006-March 2011, a total of 66 patients in a hospital in Toronto, Ontario, Canada, acquired class A extended-spectrum ß-lactamase-producing K. oxytoca with 1 of 2 related pulsed-field gel electrophoresis patterns. New cases continued to occur despite reinforcement of infection control practices, prevalence screening, and contact precautions for colonized/infected patients. Cultures from handwashing sinks in the intensive care unit yielded K. oxytoca with identical pulsed-field gel electrophoresis patterns to cultures from the clinical cases. No infections occurred after implementation of sink cleaning 3×/day, sink drain modifications, and an antimicrobial stewardship program. In contrast, a cluster of 4 patients infected with K. oxytoca in a geographically distant medical ward without contaminated sinks was contained with implementation of active screening and contact precautions. Sinks should be considered potential reservoirs for clusters of infection caused by K. oxytoca.

New Delhi metallo-ß-lactamase-1: local acquisition in Ontario, Canada, and challenges in detection.

New Delhi metallo-ß-lactamase-1 (NDM-1) is a recently identified metallo-ß-lactamase that confers resistance to carbapenems and all other ß-lactam antibiotics, with the exception of aztreonam. NDM-1 is also associated with resistance to many other classes of antibiotics. The enzyme was first identified in organisms isolated from a patient in Sweden who had previously received medical treatment in India, but it is now recognized as endemic throughout India and Pakistan and has spread worldwide. The gene encoding NDM-1 has been found predominantly in Escherichia coli and Klebsiella pneumoniae. We describe the isolation NDM-1-producing organisms from two patients in Toronto, Ontario. To the best of our knowledge, this is the first report of an organism producing NDM-1 that was locally acquired in Canada. We also discuss the evidence that NDM-1 can affect bacterial species other than E. coli and K. pneumoniae, the limited options for treatment and the difficulty laboratories face in detecting organisms that produce NDM-1.

Antimicrobial properties of hemokinin-1 against strains of Pseudomonas aeruginosa.

AIMS: In this study, we examined whether hemokinin-1, the newest member of the tachykinin family and a close relative of substance P, has antimicrobial properties which have been attributed to other neuropeptides including substance P. MAIN METHODS: Top agar assays were performed to determine the antimicrobial activity of hemokinin-1 and substance P against various microorganisms. KEY FINDINGS: Here we provide evidence that hemokinin-1 peptide possesses antimicrobial properties against some strains of Pseudomonas aeruginosa, while substance P was only marginally effective. SIGNIFICANCE: Our study is the first to link hemokinin-1 to the essential role of defending the body against microbial challenges and adds hemokinin-1 to the list of potential drugs that could help in the fight against P. aeruginosa, an opportunistic human pathogen.

Outbreak of multidrug-resistant Pseudomonas aeruginosa colonization and infection secondary to imperfect intensive care unit room design.

BACKGROUND: Pseudomonas aeruginosa has been increasingly recognized for its ability to cause significant hospital-associated outbreaks, particularly since the emergence of multidrug-resistant strains. Biofilm formation allows the pathogen to persist in environmental reservoirs. Thus, multiple hospital room design elements, including sink placement and design, can impact nosocomial transmission of P. aeruginosa and other pathogens. METHODS: From December 2004 through March 2006, 36 patients exposed to the intensive care unit or transplant units of a tertiary care hospital were infected with a multidrug-resistant strain of P. aeruginosa. All phenotypically similar isolates were examined for genetic relatedness by means of pulsed-field gel electrophoresis. Clinical characteristics of the affected patients were collected, and a detailed epidemiological and environmental investigation of potential sources was carried out. RESULTS: Seventeen of the infected patients died within 3 months; for 12 (71%) of these patients, infection with the outbreak organism contributed to or directly caused death. The source of the outbreak was traced to hand hygiene sink drains, where biofilms containing viable organisms were found. Testing by use of a commercial fluorescent marker demonstrated that when the sink was used for handwashing, drain contents splashed at least 1 meter from the sink. Various attempts were made to disinfect the drains, but it was only when the sinks were renovated to prevent splashing onto surrounding areas that the outbreak was terminated. CONCLUSION: This report highlights the importance of biofilms and of sink and patient room design in the propagation of an outbreak and suggests some strategies to reduce the risks associated with hospital sinks.

Detecting latent tuberculosis infection in hemodialysis patients: a head-to-head comparison of the T-SPOT.TB test, tuberculin skin test, and an expert physician panel.

Current guidelines advocate screening hemodialysis patients for latent tuberculosis infection; however, the tuberculin skin test (TST) is believed to be insensitive in this population. This study compared the diagnostic utility of the TST with that of an IFN-gamma assay (T-SPOT.TB) and the clinical consensus of an expert physician panel. A total of 203 patients with ESRD were evaluated for latent tuberculosis infection with the TST, T-SPOT.TB test, and an expert physician panel. Test results were compared with respect to their association with established tuberculosis risk factors. Tuberculosis infection, as estimated by the tuberculin test, T-SPOT.TB test, and expert physician panel, was detected in 12.8%, 35.5, and 26.1 of patients respectively. Among patients with a history of active tuberculosis and radiographic markers of previous infection, 78.6 and 72.7% had positive T.SPOT.TB results, compared with 21.4 and 18.2% who had positive tuberculin tests. The physician panel unanimously declared infection in these two groups. On multivariate analysis, a positive T-SPOT.TB test was associated with a history of active tuberculosis, radiographic markers of previous infection, and birth in an endemic country, whereas a physician panel diagnosis also was associated with a history of previous tuberculosis contact. The TST is insensitive in hemodialysis patients and is not recommended to be used in isolation to diagnose latent tuberculosis infection. It is suggested that a combination of T-SPOT.TB testing and medical assessment may be the most accurate screening method.

Routine use of mupirocin at the peritoneal catheter exit site and mupirocin resistance: still low after 7 years.

OBJECTIVE: The purpose of this study (the third in a series of similar studies) is to evaluate the prevalence of Staphylococcus aureus (SA), methicillin-resistant SA (MRSA) and mupirocin-resistant SA (MuRSA) carriers in a peritoneal dialysis centre where patients have been instructed to use prophylactic mupirocin ointment at the catheter exit site over the last 7 years. METHODS: Swabs were taken from catheter exit site, nares, axillae and groin in 147 chronic peritoneal dialysis out-patients between November 2003 and January 2004. Axillae/groin and nasal samples were pooled and cultured in the same medium, whereas exit site swabs were cultured separately. All SA isolated were tested for methicillin and mupirocin resistance using oxacillin screening plates and E-test strips. RESULTS: Sixteen of 147 patients (10.9%) were found to be SA carriers: of these 13 (8.8%) had a positive nasal/axillae/groin culture; two (1.4%) had both nasal/axillae/groin- and exit site-positive culture; and one (0.7%) had only exit site-positive culture. In these 16 SA carriers, we found mupirocin-resistant strains (MuRSA) in four patients (25%) and MRSA in two patients (12.5%). Among the four MuRSA carriers, one had both nasal/axillae/groin- and exit site-positive culture and three had only nasal/axillae/groin-positive culture. Three high-level resistance and one low-level resistance MuRSA carriers were isolated. One MuRSA strain was also methicillin resistant. All MRSA strains were sensitive to vancomycin and rifampicin. CONCLUSION: After 7 years' routine use of prophylactic mupirocin ointment at the catheter exit site in non-selected chronic peritoneal dialysis patients, MuRSA was found in 25% of SA strains isolated or in 2.7% of the patients. Compared with our previous study, 3 years earlier, there is no significant increase in the MuRSA prevalence in peritoneal dialysis patients who routinely apply mupirocin ointment at the catheter exit site.

Stability of reconstituted freeze-dried Bacille Calmette-Guérin used for intravesical immunotherapy for bladder cancer.

The product monographs for the commercially available products of Bacille Calmette-Guérin (BCG) state they must be used immediately following reconstitution. We hypothesized that the viability of the reconstituted preparations of BCG would not be altered for a period of up to 4 hours thus allowing a longer time interval between full preparation and its intravesical administration. Vials of freeze-dried ImmuCysttrade mark (Connaught Laboratories) and TICEtrade mark BCG (Organon-Teknika) were fully reconstituted in approximately 50 ml of saline and aliquots of the fully reconstituted product were serially diluted and inoculated onto freshly prepared Lowenstein-Jensen slants and colony counts were conducted at 0, 2, and 4 hours. The colony counts of the freeze-dried preparations of BCG varied between 0.1 and 0.3 x 108 and between 0.6 and 1.1 x 108 per reconstituted volume at 4 hours for the Connaught and TICE strains, respectively. There was no decrease in the colony counts between 0 and 4 hours for either product. There were no significant differences in the viability of the fully reconstituted freeze-dried preparation of BCG for up to 4 hours after complete reconstitution. These findings would suggest some latitude may be provided for institutions where the product is fully reconstituted prior to its actual administration.