Orla Sherlock

Comparison of the antimicrobial activity of Ulmo honey from Chile and Manuka honey against methicillin-resistant Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa.

BackgroundHoney has previously been shown to have wound healing and antimicrobial properties, but this is dependent on the type of honey, geographical location and flower from which the final product is derived. We tested the antimicrobial activity of a Chilean honey made by Apis mellifera (honeybee) originating from the Ulmo tree (Eucryphia cordifolia), against selected strains of bacteria.MethodsUlmo 90 honey was compared with manuka UMF® 25+ (Comvita®) honey and a laboratory synthesised (artificial) honey. An agar well diffusion assay and a 96 well minimum inhibitory concentration (MIC) spectrophotometric-based assay were used to assess antimicrobial activity against five strains of methicillin-resistant Staphylococcus aureus (MRSA), Escherichia coli and Pseudomonas aeruginosa.ResultsInitial screening with the agar diffusion assay demonstrated that Ulmo 90 honey had greater antibacterial activity against all MRSA isolates tested than manuka honey and similar activity against E. coli and P. aeruginosa. The MIC assay, showed that a lower MIC was observed with Ulmo 90 honey (3.1% - 6.3% v/v) than with manuka honey (12.5% v/v) for all five MRSA isolates. For the E. coli and Pseudomonas strains equivalent MICs were observed (12.5% v/v). The MIC for artificial honey was 50% v/v. The minimum bactericidal concentration for all isolates tested for Ulmo 90 honey was identical to the MIC. Unlike manuka honey, Ulmo 90 honey activity is largely due to hydrogen peroxide production.ConclusionsDue to its high antimicrobial activity, Ulmo 90 may warrant further investigation as a possible alternative therapy for wound healing.

Enhanced Discrimination of Highly Clonal ST22-Methicillin-Resistant Staphylococcus aureus IV Isolates Achieved by Combining spa, dru, and Pulsed-Field Gel Electrophoresis Typing Data

ABSTRACT ST22-methicillin-resistant Staphylococcus aureus type IV (ST22-MRSA-IV) is endemic in Irish hospitals and is designated antibiogram-resistogram type-pulsed-field group (AR-PFG) 06-01. Isolates of this highly clonal strain exhibit limited numbers of pulsed-field gel electrophoresis (PFGE) patterns and spa types. This study investigated whether combining PFGE and spa typing with DNA sequencing of the staphylococcal cassette chromosome mec element (SCCmec)-associated direct repeat unit (dru typing) would improve isolate discrimination. A total of 173 MRSA isolates recovered in one Irish hospital during periods in 2007 and 2008 were investigated using antibiogram-resistogram (AR), PFGE, spa, dru, and SCCmec typing. Isolates representative of each of the 17 pulsed-field group 01 (PFG-01) spa types identified underwent multilocus sequence typing, and all isolates were ST22. Ninety-seven percent of isolates (168 of 173) exhibited AR-PFG 06-01 or closely related AR patterns, and 163 of these isolates harbored SCCmec type IVh. The combination of PFGE, spa, and dru typing methods significantly improved discrimination of the 168 PFG-01 isolates, yielding 65 type combinations with a Simpsons index of diversity (SID) of 96.53, compared to (i) pairwise combinations of spa and dru typing, spa and PFGE typing, and dru and PFGE typing, which yielded 37, 44, and 43 type combinations with SIDs of 90.84, 91.00, and 93.57, respectively, or (ii) individual spa, dru, and PFGE typing methods, which yielded 17, 17, and 21 types with SIDs of 66.9, 77.83, and 81.34, respectively. Analysis of epidemiological information for a subset of PFG-01 isolates validated the relationships inferred using combined PFGE, spa, and dru typing data. This approach significantly enhances discrimination of ST22-MRSA-IV isolates and could be applied to epidemiological investigations of other highly clonal MRSA strains.

The effect of rapid screening for methicillin-resistant Staphylococcus aureus (MRSA) on the identification and earlier isolation of MRSA-positive patients.

OBJECTIVES (1) To determine whether rapid screening with polymerase chain reaction (PCR) assays leads to the earlier isolation of patients at risk for methicillin-resistant Staphylococcus aureus (MRSA) colonization, (2) to assess compliance with routine MRSA screening protocols, (3) to confirm the diagnostic accuracy of the Xpert MRSA real-time PCR assay (Cepheid) by comparison with culture, and (4) to compare turnaround times for PCR assay results with those for culture results. DESIGN Before-and-after study conducted in a 700-bed acute tertiary care referral hospital. Study periods were (1) a 5-week period before PCR testing began, (2) a 10-week period when the PCR assay was used, and (3) a 5-week period after PCR testing was discontinued. RESULTS Among 489 at-risk patients, MRSA was isolated from 20 (33%) of 60 patients during period 1, 77 (22%) of 349 patients during period 2, and 18 (23%) of 80 patients during period 3. Twenty-two (27%) of 82 at-risk patients were not screened during period 1, compared with 40 (10%) of 389 at-risk patients not screened during period 2 (P < .001). More MRSA-positive patients were preemptively isolated during periods 1 and 3 compared with period 2 (34 [24%] of 140 vs 28 [8%] of 389; P < .001); however, more MRSA-positive patients were isolated after notification of MRSA-positive results during period 2 (47 [13%] of 349) compared with periods 1 and 3 (2 [1%] of 140; P < .001). The sensitivity, specificity, positive predictive value, and negative predictive value of the PCR assay were 95%, 97%, 82%, and 99%, respectively. The mean turnaround time from receipt of specimens in the laboratory to PCR assay result was 2.6 hours. CONCLUSIONS Rapid screening with the Xpert MRSA PCR assay facilitated compliance with screening policies and the earlier isolation of MRSA-positive patients. Discrepant results confirm that PCR testing should be used as a screening tool rather than as a diagnostic tool.

Evaluation of screening risk and nonrisk patients for methicillin-resistant Staphylococcus aureus on admission in an acute care hospital

BACKGROUND Screening for methicillin-resistant Staphylocccus aureus (MRSA) is advocated as part of control measures, but screening all patients on admission to hospital may not be cost-effective. OBJECTIVE Our objective was to evaluate the additional yield of screening all patients on admission compared with only patients with risk factors and to assess cost aspects. METHODS A prospective, nonrandomized observational study of screening nonrisk patients ≤72 hours of admission compared with only screening patients with risk factors over 3 years in a tertiary referral hospital was conducted. We also assessed the costs of screening both groups. RESULTS A total of 48 of 892 (5%) patients was MRSA positive; 28 of 314 (9%) during year 1, 12 of 257 (5%) during year 2, and 8 of 321 (2%) during year 3. There were significantly fewer MRSA-positive patients among nonrisk compared with MRSA-risk patients: 4 of 340 (1%) versus 44 of 552 (8%), P ≤ .0001, respectively. However, screening nonrisk patients increased the number of screening samples by 62% with a proportionate increase in the costs of screening. A backward stepwise logistic regression model identified age > 70 years, diagnosis of chronic pulmonary disease, previous MRSA infection, and admission to hospital during the previous 18 months as the most important independent predictors to discriminate between MRSA-positive and MRSA-negative patients on admission (94.3% accuracy, P < .001). CONCLUSION Screening patients without risk factors increased the number of screenings and costs but resulted in few additional cases being detected. In a hospital where MRSA is endemic, targeted screening of at-risk patients on admission remains the most efficient strategy for the early identification of MRSA-positive patients.

Pilot evaluation of a ward-based automated hand hygiene training system.

A novel artificial intelligence (AI) system (SureWash; GLANTA, Dublin, Ireland) was placed on a ward with 45 staff members for two 6-day periods to automatically assess hand hygiene technique and the potential effectiveness of the automated training system. Two human reviewers assessed videos from 50 hand hygiene events with an interrater reliability (IIR) of 88% (44/50). The IIR was 88% (44/50) for the human reviewers and 80% (40/50) for the software. This study also investigated the poses missed and the impact of feedback on participation (+113%), duration (+11%), and technique (+2.23%). Our findings showed significant correlation between the human raters and the computer, demonstrating for the first time in a clinical setting the potential use of this type of AI technology in hand hygiene training.

MRSA screening: can one swab be used for both culture and rapid testing? An evaluation of chromogenic culture and subsequent Hain GenoQuick PCR amplification/detection

The use of a single swab for both MRSA culture and for rapid testing by PCR was evaluated, using the Hain GenoQuick (GQM) methicillin resistant Staphylococcus aureus (MRSA) assay for the rapid detection of MRSA, as a single swab would be the preferred option for routine diagnostic testing. GQM detected current prevalent Irish MRSA strains incorporating all known SSCmec types, including Panton-Valentine leukocidin-positive strains. Using the GQM method, all methicillin-resistant coagulase-negative staphylococci tested were confirmed to be negative, although three of seven gentamicin-resistant methicillin-sensitive Staphylococcus aureus strains tested were identified as MRSA. The theoretical ex-vivo limit of detection of the assay was 704 CFU per GQM assay reaction (1.7 × 10(4) CFU/mL) when MRSA suspensions were used for DNA extraction, or 1.4 × 10(3) CFU/swab (1.4 × 10(4) CFU/mL) using MRSA absorbed onto Copan screening swabs. Swab processing on chromogenic agar prior to PCR resulted in some inhibition of the PCR reaction, increasing the limit of detection of the assay by a factor of four. Based on 540 single swab screening specimens (nasal and groin) processed first for culture assay, then by GQM, the specificity and positive predictive value were both 100%, the negative predictive value was 92%, and the sensitivity was 57%. Culture followed by PCR from a single specimen is not optimal for the rapid detection of MRSA. Further laboratory validation of the GQM assay is required to determine the true diagnostic sensitivity and value of this kit in routine microbiology laboratories, modifying the protocol for single specimens, or using two specimens.