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Five methods for the rapid identification and differentiation of Branhamella catarrhalis from other Neisseria species in 86 respiratory specimens were compared. These tests included the 4-methylumbelliferyl butyrate (MUB), API quadFerm, B.CAT.Confirm, Gonochek II, and the Tributyrin disc. All five tests reliably and accurately identified 31 B. catarrhalis isolates. However, the MUB test was the least expensive, least labor intensive, and did not require overnight purity plates for performance. The MUB test provided same-day identification of B. catarrhalis isolates from the initial primary isolation culture.

Background Severe Acute Respiratory Syndrome (SARS) became a global epidemic in 2003. Comprehensive information on 1-year outcomes and health care utilization is lacking. Research conducted during the SARS outbreak may help inform research planning for future public health emergencies. The objective of this study was to evaluate the 1-year outcomes in survivors of SARS and their family caregivers. Method The study was prospective and observational. We evaluated 117 SARS survivors from Toronto, Ontario. Patients were interviewed and underwent physical examination, pulmonary function testing, chest radiography, a 6-minute-walk test, quality-of-life measures, and self-report of health care utilization. At 1 year, informal caregivers were identified for a survey on caregiver burden. Results The enrolled survivors of SARS were young (median age, 42 years), and most were women (67%) and health care workers (65%). At 1 year after hospital discharge, pulmonary function measures were in the normal range, but 18% of patients had a significant reduction in distance walked in 6 minutes. The Medical Outcomes Study 36-Item Short Form Health Survey (SF-36) domains were 0.3 to 1.0 SD below normal at 1 year. Of the patients, 17% had not returned to work by 1 year. Fifty-one patients required 668 visits to psychiatry or psychology practitioners. During the SARS epidemic, informal caregivers reported a decline of 1.6 SD below normal on the mental component score of the SF-36. Conclusions Most SARS survivors had good physical recovery from their illness, but some patients and their caregivers reported a significant reduction in mental health 1 year later. Strategies to ameliorate the psychological burden of an epidemic on the patient and family caregiver should be considered as part of future pandemic planning.

SUMMARYUsing multivariable models, we compared whether there were significant differences between reported outbreak and sporadic cases in terms of their sex, age, and mode and site of disease transmission. We also determined the potential role of administrative, temporal, and spatial factors within these models. We compared a variety of approaches to account for clustering of cases in outbreaks including weighted logistic regression, random effects models, general estimating equations, robust variance estimates, and the random selection of one case from each outbreak. Age and mode of transmission were the only epidemiologically and statistically significant covariates in our final models using the above approaches. Weighing observations in a logistic regression model by the inverse of their outbreak size appeared to be a relatively robust and valid means for modelling these data. Some analytical techniques, designed to account for clustering, had difficulty converging or producing realistic measures of association.

It is not understood how immune inflammation influences the pathogenesis of severe acute respiratory syndrome (SARS). One area of strong controversy is the role of interferon (IFN) responses in the natural history of SARS. The fact that the majority of SARS patients recover after relatively moderate illness suggests that the prevailing notion of deficient type I IFN-mediated immunity, with hypercytokinemia driving a poor clinical course, is oversimplified. We used proteomic and genomic technology to systematically analyze host innate and adaptive immune responses of 40 clinically well-described patients with SARS during discrete phases of illness from the onset of symptoms to discharge or a fatal outcome. A novel signature of high IFN-α, IFN-γ, and IFN-stimulated chemokine levels, plus robust antiviral IFN-stimulated gene (ISG) expression, accompanied early SARS sequelae. As acute illness progressed, SARS patients entered a crisis phase linked to oxygen saturation profiles. The majority of SARS patients resolved IFN responses at crisis and expressed adaptive immune genes. In contrast, patients with poor outcomes showed deviated ISG and immunoglobulin gene expression levels, persistent chemokine levels, and deficient anti-SARS spike antibody production. We contend that unregulated IFN responses during acute-phase SARS may culminate in a malfunction of the switch from innate immunity to adaptive immunity. The potential for the use of the gene signatures we describe in this study to better assess the immunopathology and clinical management of severe viral infections, such as SARS and avian influenza (H5N1), is therefore worth careful examination.

Background: Accurate and precise estimates of the incubation distribution of novel, emerging infectious diseases are vital to inform public health policy and to parameterize mathematical models. Methods: We discuss and compare different methods of estimating the incubation distribution allowing for interval censoring of exposures, using data from the severe acute respiratory syndrome (SARS) epidemic in 2003 as an example. Results: Combining data on unselected samples of 149 and 168 patients with defined exposure intervals from Toronto and Hong Kong, respectively, we estimated the mean and variance of the incubation period to be 5.1 day and 18.3 days and the 95th percentile to be 12.9 days. We conducted multiple linear regression on the log incubation times and found that incubation was significantly longer in Toronto than in Hong Kong and in older compared with younger patients, while it was significantly shorter in healthcare workers than in other patients. Conclusions: Our findings suggest subtle but important heterogeneities in the incubation period of SARS among different strata of patients. Robust estimation of the incubation period should be independently carried out in different settings and subgroups for novel human pathogens using valid statistical methods.

Borderline oxacillin-resistant Staphylococcus aureus (BORSA) exhibit oxacillin MIC values of 1–8 μg ml−1, but lack mecA, which encodes the low-affinity penicillin-binding protein (PBP)2a. The relationship of the BORSA phenotype with specific genetic backgrounds was assessed, as well as amino acid sequence variation in the normal PBP2. Among 38 BORSA, 26 had a common PFGE profile of genomic DNA, and were multilocus sequence type (ST)25. The other isolates were genetically diverse. Complete pbp2 sequences were determined for three BORSA, corresponding to ST25, ST1 and ST47, which were selected on the basis of lacking blaZ-encoded β-lactamase. The essential transpeptidase-domain-encoding segment of pbp2 was also sequenced from seven additional ST25 isolates. Amino acid substitutions occurred in the transpeptidase domain of all BORSA, irrespective of clonal type. A Gln629→Pro substitution was common to all ST25 BORSA, but most could be distinguished from one another by additional unique substitutions in the transpeptidase domain. The ST1 and ST47 isolates also possessed unique substitutions in the transpeptidase domain. Plasmid-mediated expression of pbp2 from an ST25 or ST1 isolate in S. aureus RN6390 increased its oxacillin MIC from 0.25 to 4 μg ml−1, while pbp2 from a susceptible strain, ATCC 25923, had no effect. Therefore, different amino acid substitutions in PBP2 of diverse BORSA lineages contribute to borderline resistance. The predominant ST25 lineage was not related to any of the five clonal complexes that contain meticillin-resistant S. aureus (MRSA), suggesting that ST25 cannot readily acquire mecA-mediated resistance.

Background An accurate prognostic model for patients with severe acute respiratory syndrome (SARS) could provide a practical clinical decision aid. We developed and validated prognostic rules for both high- and low-resource settings based on data available at the time of admission. Methods We analyzed data on all 1755 and 291 patients with SARS in Hong Kong (derivation cohort) and Toronto (validation cohort), respectively, using a multivariable logistic scoring method with internal and external validation. Scores were assigned on the basis of patient history in a basic model, and a full model additionally incorporated radiological and laboratory results. The main outcome measure was death. Results Predictors for mortality in the basic model included older age, male sex, and the presence of comorbid conditions. Additional predictors in the full model included haziness or infiltrates on chest radiography, less than 95% oxygen saturation on room air, high lactate dehydrogenase level, and high neutrophil and low platelet counts. The basic model had an area under the receiver operating characteristic (ROC) curve of 0.860 in the derivation cohort, which was maintained on external validation with an area under the ROC curve of 0.882. The full model improved discrimination with areas under the ROC curve of 0.877 and 0.892 in the derivation and validation cohorts, respectively. Conclusion The model performs well and could be useful in assessing prognosis for patients who are infected with re-emergent SARS.

Background: The USA300 strain of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) can cause severe infection and is increasingly recognized as a cause of community outbreaks. In 2004, an outbreak was identified in the Calgary Health Region (CHR). Methods: MRSA isolates were identified with standard methods at a central regional laboratory and typed via pulsed-field gel electrophoresis (PFGE). Isolates were tested by PCR for mecA , Panton–Valentine leukocidin (PVL), SCC mec , and spa genes. Cases were defined as such if a clinical isolate of the USA300 strain was noted between January 1 and September 30, 2004, and the patient had lived or traveled in CHR within 2 years before symptom onset. Demographic, clinical and risk data on all such cases were collected from several sources for statistical analysis. A case was defined as high-risk if the patient had a history of drug use, homelessness or incarceration. Results: Of 40 isolates with the USA300 PFGE pattern, all tested positive for PVL, SCC mec type IVa and spa type 008. Almost all infections (39/40, 98%) involved skin and soft tissues, except for 1 death from necrotizing hemorrhagic pneumonia; a notable proportion (38%) required hospital admission or intravenous antimicrobial therapy. The outbreak centred on the high-risk population in CHR (70%; risk ratio 169.4, 95% confidence interval 86.1–333.0). Interpretation: People with histories of illicit drug use, homelessness or recent incarceration were at highest risk for infection with CA-MRSA. The emergence and spread of this virulent strain has important implications for treatment and public health in Canada.

(Accepted 3 April 2006, first published online 2 June 2006)SUMMARYUsing isolates from reported cases of Escherichia coli O157 from Alberta, Canada in 2002,we applied randomization tests to determine if cases associated with an outbreak or statisticalspace–time cluster had more similar pulsed-field gel electrophoresis patterns, based on Dicecoefficients, than expected by chance alone. Within each outbreak and space–time cluster, weassessed the mean, median, 25th percentile, 75th percentile, standard deviation, coefficient ofvariation, and interquartile range of the Dice coefficients of each pairwise comparison amongthe isolates. To assess the statistical significance of measures of location (e.g. mean) and variation(e.g. standard deviation) we created randomization distributions using all isolates or only isolatesfrom sporadic cases. We determined that randomization tests are an appropriate tool forevaluating the similarity among isolates from cases that have been linked epidemiologically orstatistically. We found little difference between using all cases or only sporadic cases whencreating our randomization distributions.INTRODUCTIONEscherichia coli O157 is a significant human pathogenthat is routinely detected in public health surveillanceprogrammes in Europe, North America, and Japan[1–4]. It is a major cause of gastroenteritis, haemor-rhagic colitis, and haemolytic–uraemic syndromein these regions [5]. Although E. coli O157 is amajor foodborne pathogen [6], infections have alsobeen associated with contaminated drinking andrecreational water [7], direct exposure to sheddinganimals or humans [8, 9], and exposure to environ-ments contaminated with this pathogen [10]. Bothsporadic and outbreak cases have been reported, andthe use of molecular techniques has facilitated theidentification of cases associated with a commonsource [11].A variety of molecular typing methods have beenproposed for outbreak investigation and routine sur-veillance [12]. For the identification of enteric patho-gens, such as E. coli O157, the use of pulsed-field gelelectrophoresis (PFGE) has become increasinglywidespread throughout North America and theworld. The use of PFGE for surveillance has often

OBJECTIVE:To describe rates of antimicrobial resistance (AMR) amongSalmonellaandShigellaisolates reported in five Canadian provinces, focusing on clinically important antimicrobials.METHODS:The authors retrospectively investigated AMR rates among 6219Salmonellaand 1673Shigellaisolates submitted to provincial public health laboratories in Alberta, Newfoundland and Labrador, Ontario, Prince Edward Island and Saskatchewan from 1997 to 2000; these isolates were estimated to represent 41% ofSalmonellacases and 72% ofShigellacases reported by the study provinces.RESULTS:AmongSalmonellaisolates, 27% (1704 of 6215) were resistant to ampicillin, 2.2% (135 of 6122) to trimethoprim/sulfamethoxazole, 1.5% (14 of 938) to nalidixic acid, 1.2% (one of 84) to lomafloxacin and 0.08% (five of 6163) to ciprofloxacin. AmongShigellaisolates, 70% (1144 of 1643) were resistant to trimethoprim/sulfamethoxazole, 65% (1079 of 1672) to ampicillin, 3.1% (eight of 262) to nalidixic acid, 0.49% (eight of 1636) to ciprofloxacin, 0.14% (one of 700) to ceftriaxone and 0.08% (one of 1292) to ceftazidime.CONCLUSIONS:Higher rates of resistance to clinically important antimicrobials (including ciprofloxacin) were observed among bothSalmonellaandShigellaisolates than has previously been reported. Current Canadian data on rates of AMR for these pathogens are required.

Resistance to the extended-spectrum cephalosporins can occur in Salmonella species via the production of extended-spectrum and AmpC β-lactamases. We describe human infections with Salmonella enterica serotype Newport phage type 14 strains resistant to ceftazidime (CAZ) and cefoxitin (FOX) related to the handling of pet treats containing dried beef. These strains were isolated from five patients in Calgary, Alberta, Canada, during 2002 and were compared to a strain cultured from a commercial pet treat present at the property of one of the patients. The strains were resistant to FOX, CAZ, cefpodoxime, ampicillin, and chloramphenicol; intermediate resistant to ceftriaxone and cefotaxime; and sensitive to the aminoglycosides, ciprofloxacin, cefepime, and imipenem. Isoelectric focusing, multiplex PCR, and sequencing of the amplicons showed that all strains produced the plasmid-encoded AmpC β-lactamase, CMY-2. Restriction analysis of plasmid DNA following transformation demonstrated that bla CMY-2 was encoded on an approximately 140-kb plasmid. Pulsed-field gel electrophoresis showed the human and pet treat Salmonella strains to be highly related. This study is the first to implicate the transfer of multidrug-resistant Salmonella species through the handling of commercial pet treats containing animal products. In addition to documenting the first cases of human infection caused by CMY-2-producing S. enterica serotype Newport strains in Canada, this study illustrates the necessity of rapid and accurate laboratory-based surveillance in the identification of novel types of antimicrobial resistance.

We compared the results of Gram staining and culture of cerebrospinal fluid to results obtained with a rapid PCR assay for the diagnosis of meningococcal meningitis in 281 cases of suspected bacterial meningitis. PCR had a sensitivity of 97% compared to a sensitivity of 55% for culture, and the PCR specificity was 99.6%. PCR results were available within 2 h of the start of the assay.

Rapid detection and accurate identification of methicillin-resistant staphylococci are critical for the effective management of infections caused by these organisms. We describe a multiplex PCR-based assay for the direct detection of methicillin-resistant staphylococci from blood culture bottles (BacT/Alert; Organon-Teknika, Durham, N.C.). A simple lysis method followed by a multiplex PCR assay designed to detect the nuc , mecA , and bacterial 16S rRNA genes was performed. A total of 306 blood culture specimens were collected over a period of 10 months from June 1998 to April 1999, consisting of 236 blood cultures growing staphylococci (including 124 methicillin-resistant Staphylococcus spp.), 50 positive blood cultures which grew organisms other than staphylococci, and 20 blood cultures that were negative for bacterial and fungal pathogens after 5 days of incubation and terminal subculture. DNA extraction, PCR, and detection could be completed in 2.5 h. Of the positive blood cultures with staphylococci, the multiplex PCR assay had a sensitivity and specificity of 99.2% and 100%, respectively. Our results show that rapid, direct detection of methicillin-resistant staphylococci is possible, allowing clinicians to make prompt and effective decisions for the management of patients with staphylococcal bacteremia.

Objectives:To describe the investigation and management of an outbreak due to multiresistantAcinetobacter baumanniiand to determine risk factors for acquisition of the organism.Setting:A 14-bed regional burn unit in a Canadian tertiary-care teaching hospital.Design:Case-control study with multivariate analysis of potential risk factors using logistic regression analysis. Surveillance cultures were obtained from the hospital environment, from noninfected patients, and from healthcare providers.Results:A total of 31 (13%) of 247 patients with acute burn injuries acquired multiresistantA. baumanniibetween December 1998 and March 2000; 18 (58%) of the patients were infected. The organism was recovered from the hospital environment and the hands of healthcare providers. Significant risk factors for acquisition of multiresistantA. baumanniiwere receipt of blood products (odds ratio [OR], 10.8; 95% confidence interval [CI95], 3.4 to 34.4;P< .001); procedures performed in the hydrotherapy room (OR, 4.1; CI95, 1.3 to 13.1;P= .02); and increased duration of mechanical ventilation (OR, 1.1 per day; CI95, 1.0 to 1.1;P=. 02).Interventions:Improved compliance with hand hygiene, strict patient isolation, meticulous environmental cleaning, and temporary closure of the unit to new admissions.Conclusions:Acquisition of multiresistantA. baumanniiwas likely multifactorial, related to environmental contamination and contact with transiently colonized healthcare providers. Control measures addressing these potential sources of multiresistantA. baumanniiwere successful in terminating the outbreak. Ongoing surveillance and continued attention to hand hygiene and adequate environmental cleaning are essential to prevent recurrent outbreaks due to antibiotic-resistant bacteria in burn units.

The MRSA-Screen (Denka-Seiken, Tokyo, Japan) latex agglutination test was evaluated for its ability to detect PBP 2a from 200 clinical isolates of coagulase-negative staphylococci (CoNS; 84 mecA -positive strains and 116 mecA -negative strains) consisting of 108 Staphylococcus epidermidis , 37 S. saprophyticus , 15 S. haemolyticus , 11 S. hominis , 10 S. capitis , 10 S. warneri , and 3 S. lugdunensis species as well as 6 other species of CoNS. The assay was compared with susceptibility testing with an agar screen plate with oxacillin at 6 μg/ml (OXA6), by oxacillin disk diffusion (DD), by broth microdilution (BMDIL), by the E test, and with Vitek GPS-SV and Vitek GPS-107 susceptibility cards. PCR for the detection of the mecA gene was used as the “gold standard.” The sensitivities and specificities for the methods evaluated were as follows: MRSA-Screen, 100 and 100%, respectively; OXA6, 100 and 99%, respectively; DD, 98 and 62%, respectively; BMDIL, 100 and 60%, respectively; E test, 100 and 51%, respectively; Vitek GPS-SV susceptibility card, 98 and 87%, respectively; and Vitek GPS-107 susceptibility card, 100 and 61%, respectively. The MRSA-Screen test accurately and rapidly detected oxacillin resistance in CoNS.

The incidence of infections caused by methicillin-resistant Staphylococcus aureus (MRSA) continues to increase in many countries worldwide. Rapid identification of MRSA from clinical specimens and screening of high-risk patients for MRSA colonization have been found to be cost-effective measures for

Extended-spectrum β-lactamase (ESBL) activity in Escherichia coli, Klebsiella pneumoniae, or Klebsiella oxytoca can be detected by using a standard disk diffusion susceptibility test method with cefotaxime (30-μg), ceftriaxone (30-μg), ceftazidime (30-μg), cefpodoxime (10-μg), or aztreonam (30-μg) disks (2, 3). The presence of an ESBL can then be confirmed by a phenotypic confirmatory disk diffusion test recommended by the National Committee for Clinical Laboratory Standards (3) or by the double disk synergy test described by Jarlier et al. (1). The phenotypic confirmatory disk diffusion test is relatively simple to perform and easy to interpret. It requires testing of both cefotaxime (30-μg) and ceftazidime (30-μg) disks each alone and in combination with clavulanic acid (10 μg). An increase in the zone diameter of ≥5 mm for either antimicrobial agent tested in combination with clavulanic acid over that when tested alone indicates that the isolate is an ESBL producer. However, as clavulanic acid is labile, it is recommended that the disks be used immediately after preparation and that they not be stored (3). This may be an inconvenience for many clinical laboratories. Therefore, we evaluated the stability of disks containing clavulanic acid stored at −20°C for 14 consecutive days. Clavulanic acid powder was obtained from Smith Kline Beecham Pharma (Oakville, Ontario, Canada). A stock solution of clavulanic acid (1,000 μg/ml) was freshly prepared. A 10-μl aliquot was added to each of the cefotaxime (30-μg) and ceftazidime (30-μg) disks, which were then allowed to air dry at room temperature for 30 min. The cefotaxime-clavulanic acid and ceftazidime-clavulanic acid disks were placed in separate screw-capped glass vials containing dessicators (Dricap 1.0 silica gel; Multi-Sorb Technology Inc., Buffalo, N.Y.) and placed in a −20°C freezer. Each day for 14 consecutive days, the containers were removed from the freezer and brought to room temperature. The disks were removed, and the containers were closed and immediately returned to the freezer. The disks were used for phenotypic confirmatory disk diffusion testing (3) to detect ESBLs using E. coli ATCC 25922 (ESBL-negative) and a well-characterized ESBL-producing strain of E. coli (LPTP 9711). Linear regression analysis was used to determine if there was a significant change in the zone diameters over time. There was no significant change in the zone diameters obtained with any of the four disks tested with the two organisms over the 14 days of evaluation (Table ​(Table1).1). For each of the disks tested, the maximum variability in the measured zone diameters was 3 mm. There were no statistically significant changes in the zone diameters with the β-lactam disks alone in comparison to those containing clavulanic acid over the 14 days. These results suggest that disks with clavulanic acid prepared for ESBL phenotypic confirmatory disk diffusion testing (3) are sufficiently stable for use up to 14 days after preparation, provided that they are stored at −20°C. TABLE 1 Phenotypic confirmatory disk diffusion test results using cefotaxime and ceftazidime disks, with and without clavulanic acid, that were stored frozen for up to 14 daysa

The probe-based Velogene Rapid MRSA Identification Assay (ID Biomedical Corp., Vancouver, British Columbia, Canada) and the latex agglutination MRSA-Screen (Denka Seiken Co., Tokyo, Japan) were evaluated for their ability to identify methicillin-resistant Staphylococcus aureus (MRSA) and to distinguish strains of MRSA from borderline oxacillin-resistant S. aureus (BORSA; mecA -negative, oxacillin MICs of 2 to 8 μg/ml). The Velogene is a 90-min assay using a chimeric probe to detect the mecA gene. MRSA-Screen is a 15-min latex agglutination test with penicillin-binding protein 2a antibody-sensitized latex particles. We compared these assays with the BBL Crystal MRSA ID System (Becton Dickinson, Cockeysville, Md.) and with PCR for mecA gene detection. A total of 397 clinical isolates of S. aureus were tested, consisting of 164 methicillin-susceptible strains, 197 MRSA strains, and 37 BORSA strains. All assays performed well for the identification of MRSA with sensitivities and specificities for Velogene, MRSA-Screen, and BBL Crystal MRSA ID of 98.5 and 100%, 98.5 and 100%, and 98.5 and 98%, respectively. Three MRSA strains were not correctly identified by each of the Velogene and MRSA-Screen assays, but repeat testing with a larger inoculum resolved the discrepancies. The BBL Crystal MRSA ID test misclassified four BORSA strains as MRSA. Both the Velogene and the MRSA-Screen assays are easy to perform, can accurately differentiate BORSA isolates from MRSA isolates, and provide a rapid alternative for the detection of methicillin resistance in S. aureus in clinical laboratories, especially when mecA PCR gene detection is unavailable.

Using checkerboard and time-kill assays, we evaluated the in vitro activity of quinupristin-dalfopristin (RP 59500) alone and in combination with five other antimicrobial agents against 12 clinical strains of vancomycin-resistant Enterococcus faecium (VREF). In time-kill studies, six VREF strains exhibited synergism with the combination of quinupristin-dalfopristin and doxycycline and three exhibited synergism with quinupristin-dalfopristin plus ampicillin-sulbactam. Combinations of quinupristin-dalfopristin with these and other agents warrant further clinical evaluation for the treatment of serious VREF infections.

Objectives:To determine the cost-effectiveness of a policy of screening high-risk patients for methicillin-resistantStaphylococcus aureus(MRSA) colonization on admission to hospital.Setting:980-bed university-affiliated tertiary-care hospital.Patients:Between June 1996 and May 1997, patients directly transferred from another hospital or nursing home, or who had been hospitalized in the previous 3 months, were screened for MRSA within 72 hours of hospital admission.Design:Nasal, perineal, and wound swabs were obtained for MRSA screening using standard laboratory methods. Laboratory and nursing costs associated with screening patients for MRSA on admission to hospital were calculated. The costs associated with the implementation of recommended infection control measures for patients with MRSA also were determined.Results:3,673 specimens were obtained from 1,743 patients. MRSA was found on admission in 23 patients (1.3%), representing 36% of the 64 patients with MRSA identified in the hospital during the year. MRSA-colonized patients were more likely to have been transferred from a nursing home (odds ratio [OR], 6.4;P=.04) or to have had a previous history of MRSA colonization (OR, 13.1;P=.05). Laboratory and nursing costs were found to be $8.34 per specimen, for a total cost of $30,632 during the year. The average cost of implementing recommended infection control measures for patients colonized with MRSA was approximately $5,235 per patient.Conclusion:If early identification of MRSA in colonized patients prevents nosocomial transmission of the organism to as few as six new patients, the screening program would save money.

This study evaluated a PCR assay for detection of the streptococcal pyrogenic exotoxin B ( speB ) gene from tissue biopsy specimens of patients with necrotizing fasciitis. speB was detected in specimens from all 10 patients with necrotizing fasciitis due to group A streptococcus. The assay was negative for all 11 patients without culture or serologic evidence of streptococcal infection. These results suggest that the detection of speB by PCR may be useful for confirming group A streptococcal infection when cultures are negative or not available.

The in-vitro susceptibilities of 1658 blood culture isolates to ciprofloxacin and 13 other antimicrobial agents were determined, and compared with the results for isolates obtained before and after the availability of ciprofloxacin in 1989. Only six (0.6%) of 995 Enterobacteriaceae were resistant to the fluoroquinolones tested; all of the ciprofloxacin-resistant strains were isolated after 1989 (P = 0.04). No significant increase in ciprofloxacin resistance was found in Pseudomonas aeruginosa or Acinetobacter spp. No resistance to ciprofloxacin was found in 124 Staphylococcus aureus isolates prior to 1989, but five (2.4%) of 208 S. aureus strains recovered after 1989 were ciprofloxacin-resistant (P = 0.16). Rates of resistance to ciprofloxacin and other antimicrobial agents commonly used to treat bacteraemic infections have remained relatively low in this Canadian teaching hospital over the past 16 years.

The Helisal test is a quantitative enzyme immunoassay for the measurement of Helicobacter pylori-specific immunoglobulin G antibodies in saliva. This test was evaluated in comparison with culture and histopathologic examination of gastric biopsy specimens obtained from 195 patients who underwent 200 endoscopic procedures for the investigation of gastrointestinal symptoms. Forty-one (21%) patients were found to have peptic ulcer disease, and one other patient had a gastric carcinoma. H. pylori was detected in gastric biopsy specimens obtained from 98 (49%) of the procedures. The sensitivity, specificity, and positive and negative predictive values of the Helisal test were 81, 75, 76, and 80%, respectively. The test was negative for 16 (38%) of the 42 patients with peptic ulcer disease or a gastric malignancy diagnosed at endoscopy. These results suggest that the Helisal assay is only moderately accurate for the detection of H. pylori infection in symptomatic patients.

Background Feedlot cattle in North America are routinely fed subtherapeutic levels of antimicrobials to prevent disease and improve the efficiency of growth. This practice has been shown to promote antimicrobial resistance (AMR) in subpopulations of intestinal microflora including Escherichia coli. To date, studies of AMR in feedlot production settings have rarely employed selective isolation, therefore yielding too few AMR isolates to enable characterization of the emergence and nature of AMR in E. coli as an indicator bacterium. E. coli isolates (n = 531) were recovered from 140 cattle that were housed (10 animals/pen) in 14 pens and received no dietary antimicrobials (control - 5 pens, CON), or were intermittently administered subtherapeutic levels of chlortetracycline (5 pens-T), chlortetracycline + sulfamethazine (4 pens-TS), or virginiamycin (5 pens-V) for two separate periods over a 9-month feeding period. Phenotype and genotype of the isolates were determined by susceptibility testing and pulsed field gel electrophoresis and distribution of characterized isolates among housed cattle reported. It was hypothesized that the feeding of subtherapeutic antibiotics would increase the isolation of distinct genotypes of AMR E. coli from cattle. Results Overall, patterns of antimicrobial resistance expressed by E. coli isolates did not change among diet groups (CON vs. antibiotic treatments), however; isolates obtained on selective plates (i.e., MA,MT), exhibited multi-resistance to sulfamethoxazole and chloramphenicol more frequently when obtained from TS-fed steers than from other treatments. Antibiograms and PFGE patterns suggested that AMR E. coli were readily transferred among steers within pens. Most MT isolates possessed the tet(B) efflux gene (58.2, 53.5, 40.8, and 50.6% of isolates from CON, T, TS, and V steers, respectively) whereas among the MA (ampicillin-resistant) isolates, the tem1-like determinant was predominant (occurring in 50, 66.7, 80.3, and 100% of isolates from CON, T, TS, and V steers, respectively). Conclusions Factors other than, or in addition to subtherapeutic administration of antibiotics influence the establishment and transmission of AMR E. coli among feedlot cattle.

The eae gene has recently been shown to be necessary for the attaching and effacing (AE) activity of enteropathogenic Escherichia coli (EPEC) on intestinal epithelial cells. In this paper we report the cloning and nucleotide sequence of a similar gene from a strain of enterohemorrhagic E. coli (EHEC) serotype O157:H7. An EHEC eae sequence was identified which was 97% homologous to the EPEC eae gene for the first 2200 bp and 59% homologous over the last 800 bp. Both eae sequences show 50% homology to the central region of the Yersinia pseudotuberculosis inv gene. The receptor-binding domain of the inv gene product lies near the carboxyl terminus. This suggests that the predicted amino acid sequence divergence in the carboxyl termini of the eae gene products might result in different antigenic and receptor specificity of these putative adhesins.

Objective Ribavirin and corticosteroids were used widely as front-line treatments for severe acute respiratory syndrome; however, previous evaluations were inconclusive. We assessed the effectiveness of ribavirin and corticosteroids as the initial treatment for severe acute respiratory syndrome using propensity score analysis. Methods We analyzed data on 1755 patients in Hong Kong and 191 patients in Toronto with severe acute respiratory syndrome using a generalized propensity score approach. Results The adjusted excess case fatality ratios of patients with severe acute respiratory syndrome receiving the combined therapy of ribavirin and corticosteroids within 2 days of admission, compared with those receiving neither treatment within 2 days of admission, were 3.8% (95% confidence interval, −1.5 to 9.2) in Hong Kong and 2.1% (95% confidence interval, −44.3 to 48.5) in Toronto. Conclusions Our results add strength to the hypothesis that the combination of ribavirin and corticosteroids has no therapeutic benefit when given early during severe acute respiratory syndrome infection. Further studies may investigate the effects of these treatments later in disease course.

We compared the MicroScan Pos MIC Type 6 panel and AMS-Vitek Gram Positive Susceptibility Card (GPS-TA) to agar dilution screen plates for the detection of high-level aminoglycoside resistance in 182 enterococcal isolates. The specificity of the two commercial systems was 100%, with the exception of one susceptible isolate found to be streptomycin resistant by the Vitek system. The MicroScan and Vitek systems had comparable sensitivities for the detection of gentamicin resistance (90 and 95% respectively) and streptomycin resistance (85 and 78%, respectively). These results suggest that screening tests such as agar dilution screen plates, broth dilution, or disk diffusion should continue to be used to detect high-level gentamicin and streptomycin resistance.

Several factors place victims of multiple trauma at increased risk for infection. The purpose of this study was to delineate the frequency of, types of, and risk factors for infection in hospitalized trauma patients.Prospective surveillance for nosocomial infection was conducted for all trauma patients who were admitted for more than 24 hours to a tertiary-care regional trauma center between January 1 and December 31, 1996.A total of 563 patients (414 males) with a mean age of 40 years (range, 15-97 years) were followed. Most (86%) sustained blunt traumatic injuries. A total of 367 infections occurred in 209 (37%) patients for an incidence of 32.1/1,000 patient-days. The hospital stay of 37% of patients was complicated by at least one infection, involving the following sites: lower respiratory tract (28%), urinary tract (24%), surgical wound (18%), skin/soft tissue (13%), intra-abdominal (5%), primary bloodstream (5%), and other sites (8%). Infection was complicated by septic shock in 36 (10%) cases, acute respiratory distress syndrome in 32 (9%) cases, and multiorgan failure in 13 (4%) cases. Death was attributed to infection in four patients. In a multivariate analysis, infected patients were more likely to have been ventilated (odds ratio [OR] = 2.6; p0.001), to have had multiple surgical procedures (OR = 2.8; p = 0.02), to have received multiple blood transfusions (OR = 2.3; p = 0.04), and to have had a spinal cord injury (OR = 5.0; p = 0.002). First surgical procedure within 24 hours of admission was protective (OR = 0.4, p = 0.001).Trauma patients are at high risk for developing infection. Identifying patients who are at increased risk for infection may allow for early intervention and subsequent decrease in infectious morbidity.

The aim of this study was to examine the prevalence and distribution of Escherichia coli O157:H7 lineage-specific polymorphism assay (LSPA) 6 genotypes from cattle (n = 313) and clinical human (n = 203) isolates from northern and southern Alberta, Canada, to understand possible associations of genotypes with host and geographic location. The majority of cattle isolates (feedlot and dairy) typed as LSPA-6 111111 (72.2%), with proportionately higher LSPA-6 222222 (19.4%) than other LSPA-6 genotypes (10.7%). Clinical human isolates also typed primarily as LSPA-6 111111 (90.1%), but a higher percentage of genotypes (6.8%) other than LSPA-6 222222 (3.1%) was observed. A significantly higher frequency of LSPA-6 111111 in southern Alberta cattle (P < 0.0001) and a significant difference in LSPA-6 genotypes between human versus feedlot cattle from northern Alberta (P < 0.0001) were detected. LSPA-6 211111 genotype was third and second most common in cattle and humans, respectively, and several new LSPA-6 genotypes (n = 19) were also discovered. Despite avoiding over-representation of isolates from specific farms or outbreaks, higher strain diversity among cattle by pulsed-field gel electrophoresis (PFGE; 50 genotypes) in contrast to human (9 PFGE genotypes) isolates was observed. The majority of cattle (74.4%) and human (90.6%) isolates were susceptible to the antimicrobials tested. Within resistant cattle isolates, sulfisoxazole-tetracycline resistance was common (62.5%) and was accounted for by the presence of sul1 and sul2, and tet(A) and tet(B) determinants. An association between LSPA-6 and PFGE genotypes but not between geographic location and PFGE genotype for both hosts was evident.

Verotoxin-producing Escherichia coli strains of the serotype O157:H7 belong to a class of gastrointestinal pathogens that adhere to epithelial cells in a characteristic pattern known as attaching and effacing. Recent insight into the nature of E. coli O157:H7 adhesion was provided by the cloning and sequencing of the chromosomal eaeA (for E. coli attaching and effacing) gene homolog (G. Beebakhee, M. Louie, J. De Azavedo, and J. Brunton, FEMS Microbiol. Lett. 91:63-68, 1992, and J. Yu and J. B. Kaper, Mol. Microbiol. 6:411-417, 1992) and isolation of a 60-MDa plasmid referred to as pO157 (I. Toth, M. L. Cohen, H. S. Rumschlag, L. W. Riley, E. H. White, J. H. Carr, W. W. Bond, and I. K. Wachsmuth, Infect. Immun. 58:1223-1231, 1990, and S. Tzipori, H. Karch, K. I. Wachsmuth, R. M. Robins-Browne, A. D. O'Brien, H. Lior, M. L. Cohen, J. Smithers, and M. M. Levine, Infect. Immun. 55:3117-3125, 1987) and an approximately 94-kDa outer membrane protein (94-kDa OMP; P. Sherman, F. Cockerill III, R. Soni, and J. Brunton, Infect. Immun. 59:890-899, 1991). In this study, we examined the gene products of both eaeA and pO157 in relation to the 94-kDa OMP and as candidate effectors for O157:H7 attachment-effacement. Peptide sequencing and immunoassay demonstrated that the C. coli O157:H7 eaeA gene product is distinct from the 94-kDa OMP. Using ultrastructural analyses, we found that both parent and pO157 plasmid-cured O157:H7 strains demonstrated attaching and effacing adhesion to host epithelial cells and reacted equally well to rabbit antiserum raised against the 94-kDa OMP. By both transmission electron microscopy and light microscopy, E. coli HB101 transformed separately with the cloned eaeA gene and the pO157 plasmid did not form attaching and effacing lesions on cultured epithelial cells in vitro and rabbit intestinal tissues in vivo. Since additional determinants may mediate the attaching and effacing phenotype, we examined transposon TnphoA mutants constructed from E. coli O157:H7 strain CL8. Two TnphoA mutants were found deficient in bacterial factors that are necessary for O157:H7 attachment-effacement and likely distinct from the eaeA gene product.