CPHLN recommendations for the laboratory detection of Shiga toxin-producing Escherichia coli (O157 and non-O157).

Shiga toxin-producing Escherichia coli (STEC) are important enteric pathogens responsible for sporadic cases and outbreaks of gastroenteritis. E.coli O157:H7/NM (STEC O157) are the most commonly known STEC serotypes but it is now increasingly apparent that non-O157 STEC serotypes have been underreported in the past because they were not part of routine screening in many front-line laboratories. The Canadian Public Health Laboratory Network (CPHLN) has identified the need for improved detection and surveillance of non-O157 STEC and has developed the following recommendations to assist in the decision-making process for clinical and reference microbiology laboratories. These recommendations should be followed to the best of a laboratory's abilities based on the availability of technology and resources. The CPHLN recommends that when screening for the agents of bacterial gastroenteritis from a stool sample, front-line laboratories use either a chromogenic agar culture or a culture-independent diagnostic test (CIDT). CIDT options include nucleic acid amplification tests (NAATs) to detect Shiga toxin genes or enzyme immunoassays (EIAs) to detect Shiga toxins. If either CIDT method is positive for possible STEC, laboratories must have a mechanism to culture and isolate STEC in order to support both provincial and national surveillance as well as outbreak investigations and response. These CPHLN recommendations should result in improved detection of STEC in patients presenting with diarrhea, especially when due to the non-O157 serotypes. These measures should enhance the overall quality of healthcare and food safety, and provide better protection of the public via improved surveillance and outbreak detection and response.

Gepotidacin (GSK2140944) In Vitro Activity against Gram-Positive and Gram-Negative Bacteria.

Gepotidacin is a first-in-class, novel triazaacenaphthylene antibiotic that inhibits bacterial DNA replication and has in vitro activity against susceptible and drug-resistant pathogens. Reference in vitro methods were used to investigate the MICs and minimum bactericidal concentrations (MBCs) of gepotidacin and comparator agents for Staphylococcus aureus, Streptococcus pneumoniae, and Escherichia coli Gepotidacin in vitro activity was also evaluated by using time-kill kinetics and broth microdilution checkerboard methods for synergy testing and for postantibiotic and subinhibitory effects. The MIC90 of gepotidacin for 50 S. aureus (including methicillin-resistant S. aureus [MRSA]) and 50 S. pneumoniae (including penicillin-nonsusceptible) isolates was 0.5 µg/ml, and for E. coli (n = 25 isolates), it was 4 µg/ml. Gepotidacin was bactericidal against S. aureus, S. pneumoniae, and E. coli, with MBC/MIC ratios of ≤4 against 98, 98, and 88% of the isolates tested, respectively. Time-kill curves indicated that the bactericidal activity of gepotidacin was observed at 4× or 10× MIC at 24 h for all of the isolates. S. aureus regrowth was observed in the presence of gepotidacin, and the resulting gepotidacin MICs were 2- to 128-fold higher than the baseline gepotidacin MICs. Checkerboard analysis of gepotidacin combined with other antimicrobials demonstrated no occurrences of antagonism with agents from multiple antimicrobial classes. The most common interaction when testing gepotidacin was indifference (fractional inhibitory concentration index of >0.5 to ≤4; 82.7% for Gram-positive isolates and 82.6% for Gram-negative isolates). The postantibiotic effect (PAE) of gepotidacin was short when it was tested against S. aureus (≤0.6 h against MRSA and MSSA), and the PAE-sub-MIC effect (SME) was extended (>8 h; three isolates at 0.5× MIC). The PAE of levofloxacin was modest (0.0 to 2.4 h), and the PAE-SME observed varied from 1.2 to >9 h at 0.5× MIC. These in vitro data indicate that gepotidacin is a bactericidal agent that exhibits a modest PAE and an extended PAE-SME against Gram-positive and -negative bacteria and merits further study for potential use in treating infections caused by these pathogens.

In Vitro Activity of Gepotidacin (GSK2140944) against Neisseria gonorrhoeae.

Gepotidacin (formerly GSK2140944) is a novel, first-in-class, triazaacenaphthylene antibacterial that inhibits bacterial DNA gyrase and topoisomerase IV via a unique mechanism and has demonstrated in vitro activity against Neisseria gonorrhoeae, including drug-resistant strains, and also targets pathogens associated with other conventional and biothreat infections. Broth microdilution was used to evaluate the MIC and minimum bactericidal concentration (MBC) activity of gepotidacin and comparators against 25 N. gonorrhoeae strains (including five ciprofloxacin-nonsusceptible strains). Gepotidacin activity was also evaluated against three N. gonorrhoeae strains (including a ciprofloxacin-nonsusceptible strain) for resistance development, against three N. gonorrhoeae strains (including two tetracycline- and azithromycin-nonsusceptible strains) using time-kill kinetics and checkerboard methods, and against two N. gonorrhoeae strains for the investigation of postantibiotic (PAE) and subinhibitory (PAE-SME) effects. The MIC50 and MIC90 for gepotidacin against the 25 N. gonorrhoeae isolates tested were 0.12 and 0.25 µg/ml, respectively. The MBC50 and MBC90 for gepotidacin were 0.25 and 0.5 µg/ml, respectively. Gepotidacin was bactericidal, and single-step resistance selection studies did not recover any mutants, indicating a low rate of spontaneous single-step resistance. For combinations of gepotidacin and comparators tested using checkerboard methods, there were no instances where antagonism occurred and only one instance of synergy (with moxifloxacin; fractional inhibitory concentration, 0.375). This was not confirmed by in vitro time-kill studies. The PAE for gepotidacin against the wild-type strain ranged from 0.5 to >2.5 h, and the PAE-SME was >2.5 h. These in vitro data indicate that further study of gepotidacin is warranted for potential use in treating infections caused by N. gonorrhoeae.

Plate augmentation for femoral nonunion: more than just a salvage tool?

OBJECTIVE: The aim of the current study was to determine whether plate augmentation was a successful treatment algorithm for selected femoral nonunions initially managed with intramedullary nailing. MATERIALS AND METHODS: A total of 30 femoral nonunion cases were managed using the plate augmentation strategy with 13 primary cases and 17 multi-operated femurs (avg 2.8 ineffective procedures). Adjunctive strategies included autologous bone grafting and/or BMP for atrophic/oligotrophic and bone defect cases. Deformity correction was performed when required. RESULTS: Osseous union occurred in 29 of 30 cases. One multi-operated case with bone defect and prior infection required repeat autologous grafting prior to union. CONCLUSION: Plate augmentation should be added to the armamentarium for management of selected femoral nonunion that have failed initial intramedullary nailing.

Wedge effect following intramedullary hip screw fixation of intertrochanteric proximal femur fracture.

INTRODUCTION: The aim of the current study was to determine whether application of an intramedullary hip screw for definitive management of intertrochanteric fracture was associated with post-operative deformity. Specifically this study investigated whether nail insertion would cause a "wedge effect" of the intertrochanteric fracture manifesting as lateralization of the femoral shaft and varus malalignment. MATERIALS AND METHODS: The trauma database at the University of Pittsburgh Medical Center was investigated to identify all intertrochanteric fractures (AO/OTA 31A) over the past 3 years treated with an IMHS. Fractures eligible for inclusion were performed under the supervision of a fellowship trained orthopedic trauma surgeon. All fractures were reduced in optimal alignment using percutaneous or mini-open strategies during the reaming process and nail insertion. The entry portal was over-reamed by at least 1.5 mm. Cases selected for review of the "wedge effect" had optimal post-operative imaging allowing for assessment of discrepancy between the operative and normal hip. RESULTS: Forty six patients with an average age of 77 years were included for study. Fifty percent were classified as unstable patterns. Shaft lateralization following IMHS fixation of the fractured hip was found to be an average of 7 mm greater than the contralateral intact hip (p < 0.001) (range 0-30 mm). The neck-shaft angle of the operative hips was 129° as compared to 133° on the intact side (p = 0.009). The stability of the fracture pattern was not predictive for post-operative lateralization of the femoral shaft or varus angulation (p > 0.05) (Table 2). There was no difference in post-operative deformity among techniques used for maintenance of reduction during reaming and nail insertion (p > 0.05). Despite deformity, all cases demonstrated radiographic radiographic fracture union. CONCLUSION: Despite attention to detail, the application of an intramedullary hip screw for intertrochanteric fracture has the tendency to lateralize the shaft relative to the head/neck segment (The "wedge effect").

Antimicrobial activity of solithromycin against serotyped macrolide-resistant Streptococcus pneumoniae isolates collected from U.S. medical centers in 2012.

Solithromycin, a next-generation macrolide and novel fluoroketolide, was tested against a 2012 collection of serotyped U.S. macrolide-resistant Streptococcus pneumoniae isolates associated with community-acquired bacterial pneumonia (CABP). Against all 272 isolates, solithromycin demonstrated high potency (MIC50/90, 0.06/0.25 µg/ml), and it inhibited all strains at MICs of ≤0.5 µg/ml, including the two most prevalent macrolide-resistant serotypes (19A and 35B). These data support the continued clinical development of solithromycin for the treatment of multidrug-resistant CABP.

Variant influenza A (H1N1) virus infection in Canada.

There has been an increase in influenza A variant detections in the US in recent years. In September 2012, an Ontario resident was diagnosed with influenza A (H1N1) variant infection. The demonstrated cross reactivity with the A(H1N1)pdm09 H1 gene CDC realtime PCR suggests that laboratories that only use the pdm09 H1 gene PCR to confirm this subtype would incorrectly report this variant as a A(H1N1)pdm09 subtype unless they were doing further molecular investigations.

Antimicrobial activity of daptomycin tested against gram-positive strains collected in European hospitals: results from 7 years of resistance surveillance (2003-2009).

Daptomycin is a cyclic lipopeptide approved by the European medicines Agency (EMEA) for the treatment of complicated skin and soft tissue infections (cSSTI) and Staphylococcus aureus bacteremia and endocarditis. We evaluated the in vitro activity of daptomycin and comparators tested against clinical isolates from european hospitals over a 7-year period (2003-2009). A total of 36,769 consecutive isolates were collected in 34 medical centers located in 13 European countries, Turkey and Israel. the collection included S. aureus (18,352; 27.2% oxacillin-resistant [MRSA]); coagulase-negative staphylococci (CoNS; 6,874), Enterococcus spp. (7,241; 9.4% vancomycin-resistant), ß-hemolytic (3,009), viridans group streptococci (1,176), and Streptococcus bovis/gallolyticus (107). The organisms were isolated mainly from patients with bloodstream infection (56%) or cSSTI (23%). Daptomycin was very active against S. aureus and CoNS (MIC(50/90), 0.25/0.5 mg/l for both organisms), and its activity was not adversely influenced by oxacillin resistance. All Enterococcus faecalis strains were susceptible to daptomycin (MIC(50/90), 1/1 mg/l). Daptomycin (MIC(50/90), 2/2 mg/l; 100.0% susceptible) and linezolid (MIC(50/90), 1/2 mg/l; 99.7% susceptible) were the most active agents tested against vancomycin-resistant E. faecium. Vancomycin- resistant and -susceptible enterococcal strains were equally susceptible to daptomycin. Daptomycin was also active against ß-hemolytic streptococci (MIC(50/90), 0.06/0.25 mg/l; 100.0% susceptible), viridans group streptococci (MIC(50/90), 0.25/0.5 mg/l; 99.8% susceptible) and S. bovis (MIC(50/90), 0.06/0.12 mg/l; 100.0% susceptible).In summary, daptomycin was very potent against this large collection (36,769) of Gram-positive organisms isolated in european hospitals, and its activity remained stable across the 7-year period evaluated (2003-2009), using reference methods and interpretive criteria. Decreases in daptomycin potency were not observed since EMEA approval and widespread clinical use, and emerging resistance to other compounds did not adversely influence daptomycin activity against contemporary Gram-positive species.

Eight-year (2002-2009) summary of the linezolid (Zyvox® Annual Appraisal of Potency and Spectrum; ZAAPS) program in European countries.

The linezolid surveillance network (ZAAPS program) has been monitoring linezolid activity and susceptibility rates for eight years (2002-2009) in european medical centers. Samples from 12-24 sites annually in 11 countries were monitored by a central laboratory design using reference MIC methods with international and regional interpretations (EUCAST). A total of 13,404 gram-positive pathogens were tested from 6 pathogen groups. Linezolid remained without documented resistance from 2002 through 2005, but beginning in 2006 resistant strains emerged at very low rates among Staphylococcus aureus (G2576T mutant in ireland, 2007), coagulase-negative staphylococci (CoNS; usually Staphylococcus epidermidis, France and Italy in 2006-2009) and enterococci (Enterococcus faecium in Germany [2006, 2008, 2009] and E. faecalis in Sweden [2008], United Kingdom [2008] and Germany [2009]); all but one strain having a target mutation. A mobile cfr was detected in an italian CoNS strain (2008 and 2009), and clonal spread was noted for linezolid-resistant strains (PFGE results). Overall the linezolid susceptibility rates were >99.9, 99.7 and 99.6% for S. aureus, CoNS and enterococci, respectively; and all streptococcal strains were susceptible (MIC(90), 1 mg/l). In conclusion, the ZAAPS program surveillance confirmed high, sustained levels of linezolid activity from 2002-2009 and without evidence of MIC creep or escalating resistance in gram-positive pathogens across monitored european nations.

Nonlinear mirror modelocking of a bounce geometry laser.

We present the investigation of nonlinear mirror modelocking (NLM) of a bounce amplifier laser. This technique, a potential rival to SESAM modelocking, uses a nonlinear crystal and a dichroic mirror to passively modelock a Nd:GdVO(4) slab bounce amplifier operating at 1063nm. At 11.3W, we present the highest power achieved using the NLM technique, using type-II phase-matched KTP, with a pulse duration of 57ps. Using type-I phase-matched BiBO, modelocking was achieved with a shorter pulse duration of 5.7ps at an average power of 7.1W.

Sustained antimicrobial activity of tigecycline against methicillin-resistant Staphylococcus aureus (MRSA) from United States Medical Centers from 2004 through 2008.

Tigecycline, a glycylcycline, has been approved by the United States Food and Drug Administration (USA-FDA) for the treatment of complicated skin and skin structure infections, intra-abdominal infections and community-acquired bacterial pneumonia. based on broth microdilution minimum inhibitory concentration (MIC) testing, tigecycline demonstrated sustained high activity (MIC(50/90), 0.12/0.25 mg/L) against a contemporary collection (10,242) of methicillin (oxacillin)-resistant Staphylococcus aureus (MRSA) collected from 32 USA hospitals over a 5-year period (2004-2008). Tigecycline MIC distribution did not vary significantly during the study period and only three isolates (0.03%) were non-susceptible at USA-FDA breakpoints. Vancomycin (MIC(90), 1 mg/L), trimethoprim/sulfamethoxazole (MIC( 90), <0.5 mg/L) and linezolid (MIC(90), 2 mg/L) were also very active. The results of this study indicate that tigecycline potency and spectrum against MRSA have not changed since its initial regulatory approval by the USA-FDA.

Characterization of macrolide efflux pump mef subclasses detected in clinical isolates of Streptococcus pyogenes isolated between 1999 and 2005.

The macrolide efflux mechanism of resistance, mef, was characterized in community-acquired respiratory tract infections with Streptococcus pyogenes. Fifty-four (4.6%) M phenotype isolates were screen tested as negative for mef(A). Of these 54 isolates, 5 (0.4%), 27 (2.3%), and 1 (0.1%) were considered to be mef(I) positive, a novel mosaic variant of mef, or a novel subclass of mef, respectively. This study shows (i) the definitive presence of mef(E) in S. pyogenes and its global distribution, (ii) the presence of a mosaic variant of mef composed of mef(A) and mef(E), (iii) the previously undescribed presence of mef(I) in S. pyogenes, and (iv) the presence of a novel subclass of mef in S. pyogenes.

Activity of telithromycin and comparators against isolates of Legionella pneumophila collected from patients with community-acquired respiratory tract infections: PROTEKT Years 1-5.

The in-vitro activity of telithromycin and comparator antibacterial agents was determined against clinical isolates of Legionella pneumophila collected in the PROTEKT surveillance study. In total, 133 isolates were collected between 1999 and 2004 from 13 countries (Australia, Belgium, Czech Republic, France, Germany, Hungary, Ireland, Italy, Japan, Portugal, Spain, Sweden and the USA). MICs were determined by broth microdilution. Telithromycin maintained activity between Year 1 (MIC(90) 0.015 mg/L) and Year 5 (MIC(90) 0.03 mg/L), as did the comparator antibacterial agents. Telithromycin appears to be a candidate for coverage of legionellosis in the empirical treatment of community-acquired respiratory tract infection.

High power scaling of a passively modelocked laser oscillator in a bounce geometry.

In this paper we present the first operation and power scaling of a modelocked Nd:YVO4 bounce laser oscillator at 1064 nm. We obtain up to 16.7 W of average output power from 38 W of pump power, in a continuous-wave modelocked pulse train with 30 ps pulses at a repetition rate of 78 MHz. We then use a Master Oscillator Power Amplifier (MOPA) configuration utilising another bounce amplifier, to achieve 60 W of modelocked output power.

In vitro activity of telithromycin against Gram-negative bacterial pathogens.

OBJECTIVES: To investigate the in vitro activity of the ketolide anti-bacterial telithromycin against a range of commensal bacteria and common aerobic Gram-negative respiratory and non-respiratory pathogens. METHODS: Isolates were derived from both clinical material supplied by centres in various European countries and patients with community-acquired respiratory tract infections (RTIs) from centres worldwide as part of a longitudinal surveillance study. Telithromycin susceptibility testing was conducted using methods in accordance with Clinical and Laboratory Standards Institute (CLSI) guidelines and interpreted using CLSI breakpoints. RESULTS: Telithromycin displayed the highest activity against clinical isolates of Haemophilus spp., Neisseria spp., Bordetella pertussis, Legionella pneumophila and Moraxella catarrhalis, with low activity against a number of other bacterial species, including Acinetobacter spp., Enterobacteriaceae spp., Vibrio spp., Campylobacter jejuni, Aeromonas hydrophila, Plesiomonas shigelloides and Pseudomonas aeruginosa. CONCLUSIONS: Telithromycin provides coverage of key Gram-negative respiratory tract pathogens, but has minimal activity against Gram-negative non-respiratory pathogens and commensal bacteria. These data support the use of telithromycin as an alternative empirical therapy for community-acquired RTIs.

Global distribution of TEM-1 and ROB-1 beta-lactamases in Haemophilus influenzae.

OBJECTIVES: To determine the global distribution of TEM-1 and ROB-1 beta-lactamases in Haemophilus influenzae isolated from patients with community-acquired respiratory tract infection during the first 4 years of the PROTEKT study (1999-2003). To investigate the activities of commonly used antibiotics against these isolates. METHODS: For 14 870 H. influenzae, MIC testing was performed using NCCLS broth microdilution methodology. For 2225 beta-lactamase-positive (BLP) H. influenzae, TEM-1 and ROB-1 genes were detected using a Taqman PCR method. RESULTS: beta-Lactamase positivity was 15.0% overall but varied greatly by country (<5% in several countries to 67.9% in Taiwan). Prevalences of TEM-1 and ROB-1 BLP H. influenzae were 93.7% and 4.6%, respectively, however almost all ROB-1 isolates were found in Canada, the USA and Mexico. ROB-1 isolates (n = 102) were less susceptible against cefaclor (29.4% versus 87.6%) and cefprozil (42.2% versus 91.9%) than TEM-1 (n = 2085) isolates. Differences in susceptibility rates for chloramphenicol, co-trimoxazole and tetracycline were also found between the two groups. CONCLUSIONS: The ROB-1 beta-lactamase was found almost exclusively in North America and was more active against cefaclor and cefprozil than the TEM-1 beta-lactamase.

Global distribution of Streptococcus pneumoniae serotypes isolated from paediatric patients during 1999-2000 and the in vitro efficacy of telithromycin and comparators.

Few data exist on the distribution of Streptococcus pneumoniae serotypes in many countries and in non-invasive disease overall. Here, data are presented from 772 paediatric isolates from children with community-acquired respiratory tract infections isolated from the PROTEKT global surveillance study during 1999-2000. Overall, 60.0 % of isolates were covered by the 7-valent pneumococcal vaccine formulation (PCV7), with greater coverage in the USA compared with Europe (69.6 vs 55.5 %, P = 0.014). Geographically dispersed clones of serogroups 3, 11 and 15 accounted for most of the isolates outside PCV7 coverage. Overall, macrolide, penicillin and cotrimoxazole non-susceptibility rates were high; however, all isolates were susceptible to telithromycin. Although only 7.4 % of isolates were resistant to amoxycillin/clavulanate, a higher prevalence of resistance was found in isolates from the USA and South Korea. This study shows the feasibility and importance of serotyping antibiotic surveillance study isolates and the potential of telithromycin as an important option for empiric therapy.

Impact of ketolides on resistance selection and ecologic effects during treatment for respiratory tract infections.

Ketolides are a new class of antibacterials that have been specifically developed for the treatment of community-acquired respiratory tract infections in an era of increasing resistance among major etiologic pathogens. These agents possess several unique structural features, including a 3-keto function and a large aromatic side chain, that confer not only a mode of action that differentiates them from the macrolide class but also a reduced potential to induce--or select for--resistant strains. Studies also suggest that ketolides such as telithromycin have a lower ecologic impact on the body's microflora than agents such as clarithromycin and amoxicillin-clavulanate, potentially reducing the risk of emergence of resistant strains and the spread of such resistance to pathogenic species. Therefore, available evidence suggests that ketolides may not only provide important new treatment options in an era of increasing resistance but may also contribute to reducing the pressure for development of further resistance. Clearly, further studies are required to confirm this low resistance potential once the ketolide agents become more widely used in routine practice.