Search PubMed⌕ Search

Biomedical subjects

D E Low

Publications and source records attributed to D E Low.

At least 109 records · Page 6Linked to original sources
PubMed1998

Development of specific nested oligonucleotide PCR primers for the Streptococcus iniae 16S-23S ribosomal DNA intergenic spacer.

Streptococcus iniae is a cause of septicemia, meningoencephalitis, and death in farmed fish and of cellulitis in human beings. A set of nested oligonucleotide PCR primers that specifically amplified a 373-bp subunit from a variety of clinical isolates from farmed fish and human patients were constructed from a 524-bp consensus sequence of the S. iniae 16S-23S ribosomal DNA intergenic spacer.

Animals↗
PubMed1997

Invasive infections due to a fish pathogen, Streptococcus iniae. S. iniae Study Group.

BACKGROUND: Streptococcus iniae is a pathogen in fish, capable of causing invasive disease and outbreaks in aquaculture farms. During the winter of 1995-1996 in the greater Toronto area there was a cluster of four cases of invasive S. iniae infection in people who had recently handled fresh, whole fish from such farms. METHODS: We conducted a prospective and retrospective community-based surveillance for cases of S. iniae infection in humans. To obtain a large sample of isolates, we studied cultures obtained from the surface of fish from aquaculture farms. Additional isolates were obtained from the brains of infected tilapia (oreochromis species). All the isolates were characterized by pulsed-field gel electrophoresis (PFGE). RESULTS: During one year, our surveillance identified a total of nine patients with invasive S. iniae infection (cellulitis of the hand in eight and endocarditis in one). All the patients had handled live or freshly killed fish, and eight had percutaneous injuries. Six of the nine fish were tilapia, which are commonly used in Asian cooking. Thirteen additional S. iniae isolates (2 from humans and 11 from infected tilapia) were obtained from normally sterile sites. The isolates from the nine patients were indistinguishable by PFGE and were highly related to the other clinical isolates. There was substantial genetic diversity among the 42 surveillance isolates from the surface of fish, but in 10 isolates the PFGE patterns were identical to those from the patients with S. iniae infection. CONCLUSIONS: S. iniae can produce invasive infection after skin injuries during the handling of fresh fish grown by aquaculture. We identified a clone of S. iniae that causes invasive disease in both humans and fish.

Adult↗
PubMed1997

A practical guide for the diagnosis and treatment of acute sinusitis.

OBJECTIVE: To develop guidelines for the diagnosis and management of acute sinusitis. OPTIONS: Diagnostic clinical criteria and imaging techniques, the role of antimicrobial therapy and duration of treatment, and the role of adjunct therapy, including decongestants, glucocorticosteroids and nasal irrigation. OUTCOMES: Improved accuracy of clinical diagnosis, better utilization of imaging techniques and rational use of antimicrobial therapy. EVIDENCE: A MEDLINE search for relevant articles published from 1980 to 1996 using the MeSH terms "sinusitis," "acute sinusitis," "respiratory infections," "upper respiratory infections," "sinusitis" and "diagnosis," "sinusitis" and "therapy," "sinusitis" and "etiology," and "antimicrobial resistance" and search for additional articles from the reference lists of retrieved articles. Papers referring to chronic sinusitis, sinusitis in compromised patients and documented nonbacterial sinusitis were excluded. The evidence was evaluated by participants at the Canadian Sinusitis Symposium, field in Toronto on April 26-27, 1996. VALUES: A hierarchical evaluation of the strength of evidence modified from the methods of the Canadian Task Force on the Periodic Health Examination was used. Strategies were identified to deal with problems for which no adequate clinical data were available. Recommendations arrived at by consensus of the symposium participants were included. BENEFITS, HARMS AND COSTS: Increased awareness of acute sinusitis, accurate diagnosis and prompt treatment should reduce costs related to unnecessary investigations, time lost from work and complications due to inappropriate treatment. As well, physicians will be better able to decide which patients will not require antimicrobial therapy, thus saving the patient the cost and potential side effects of treatment. RECOMMENDATIONS: Clinical diagnosis can usually be made from the patient's history and findings on physical examination only. Five clinical findings comprising 3 symptoms (maxillary toothache, poor response to decongestants and a history of coloured nasal discharge) and 2 signs (purulent nasal secretion and abnormal transillumination result) are the best predictors of acute bacterial sinusitis (level I evidence). Transillumination is a useful technique in the hands of experienced personnel, but only negative findings are useful (level III evidence). Radiography is not warranted when the likelihood of acute sinusitis is high or low but is useful when the diagnosis is in doubt (level III evidence). First-line therapy should be a 10-day course of amoxicillin (trimethoprim-sulfamethoxazole should be given to patients allergic to penicillin) (level I evidence) and a decongestant (level III evidence). Patients allergic to amoxicillin and those not responding to first-line therapy should be switched to a second-line agent. As well, patients with recurrent episodes of acute sinusitis who have been assessed and found not to have anatomic anomalies may also benefit from second-line therapy (level III evidence). VALIDATION: The recommendations are based on consensus of Canadian and American experts in infectious diseases, microbiology, otolaryngology and family medicine. The guidelines were reviewed independently for the advisory committee by 2 external experts. Previous guidelines did not exist in Canada.

Acute Disease↗
PubMed1997

Population-based surveillance for group A streptococcal necrotizing fasciitis: Clinical features, prognostic indicators, and microbiologic analysis of seventy-seven cases. Ontario Group A Streptococcal Study.

PURPOSE: To determine the incidence of group A streptococcal necrotizing fasciitis in Ontario, Canada, and to describe the clinical features, outcome, and microbiologic characteristics of this infection. PATIENTS AND METHODS: Prospective, population-based surveillance for invasive group A streptococcal infections was conducted in Ontario from November 1991 to May 1995. All 77 patients meeting clinical and/or histopathologic criteria for streptococcal necrotizing fasciitis were included. Demographic and clinical information was obtained by patient interviews and chart review. Group A streptococci were characterized by M-protein and T-agglutination typing, and polymerase chain reaction (PCR) detection of streptococcal pyrogenic exotoxin genes A and C (speA; speC). RESULTS: The incidence of group A streptococcal necrotizing fasciitis increased during the study from 0.085 per 100,000 population in the first year to 0.40 per 100,000 population in the last year (P < 0.001). The median age of cases was 57.5 years and the rate of disease increased with increasing age. Seventy-nine percent of cases were community-acquired, 11% were nosocomial, and 10% were acquired in a nursing home. Forty-seven percent of cases were associated with the presence of streptococcal toxic shock syndrome (Strep TSS) and 46% were bacteremic. Thirty-four percent of cases died and mortality was correlated with increasing age (P = 0.006), presence of hypotension (P = 0.01), and bacteremia (P = 0.03). The most common streptococcal serotypes were M1 (35%) and M3 (25%). Forty-one percent of strains possessed the speA gene and 30% the speC gene. Outcome was not correlated with M-type or the presence of spe genes. CONCLUSIONS: The incidence of necrotizing fasciitis caused by group A streptococcus increased in Ontario between 1992 and 1995. Elderly individuals were more likely to acquire the disease and to die from it. Mortality because of streptococcal necrotizing fasciitis was also associated with the presence of hypotension, Strep TSS, or bacteremia, but not with M-type or the presence of pyrogenic exotoxin genes.

Aged↗
PubMed1997

Complications associated with laparoscopic anti-reflux surgery: one multispecialty clinic's experience.

BACKGROUND: The records of all patients with significant complications of laparoscopic anti-reflux surgery (LARS) seen at our institution between June 1993 and September 1996 were reviewed. Specifically excluded were patients who had mild perioperative complications or postoperative dysphagia that either did not require bougienage or responded to one to two dilations. Data collected included patient demographics; type of surgery; complication and its presentation; response to medical, endoscopic, and/or surgical therapy; and outcomes. RESULTS: Nine patients (five men and four women, mean age 59 years) presented at a mean of 4 months post-LARS (seven Nissen fundoplications and two Hill posterior gastropexy repairs). Symptoms included refractory dysphagia (4), intractable gas bloat (5), various degrees of chest or abdominal pain (4), and incapacitating diarrhea (3). Findings included tight repair (4), vagal nerve injury with gastroparesis (4) and/or diarrhea (3), and esophageal or gastric perforation (3). Additional findings included proximal gastric ulcers (3), volvulus (1), and incarcerated intrathoracic hernia (1). Patients with dysphagia had moderate improvement after a mean of 3 +/- 0.6 (standard error of the mean) additional dilations, whereas four patients required five reoperations to date. Seven of the nine patients had clinical improvement, whereas two had refractory symptoms at a mean follow-up of 10 months. CONCLUSIONS: Although LARS has supplanted open surgery in many centers, refractory complications occur in a subset of patients and require reoperation in approximately one half of those referred to a multispecialty clinic.

Catheterization↗
PubMed1997

A review of in-vitro antibacterial activity of quinupristin/dalfopristin against methicillin-susceptible and -resistant Staphylococcus aureus.

Methicillin-resistant Staphylococcus aureus (MRSA) presently represents approximately 30% of clinical isolates of S. aureus in the USA. Many strains are additionally resistant to erythromycin, 15- and 16-membered macrolides (e.g. azithromycin, spiramycin), clindamycin, aminoglycosides and/or quinolones. A review of the literature shows that quinupristin/dalfopristin, a semisynthetic derivative of pristinamycin, exhibits good in-vitro activity against methicillin-sensitive S. aureus and MRSA (mean MIC90 0.25-1.0 and 0.5-2.0 mg/L, respectively). Its in-vitro bacteriostatic activity is also unaffected by resistance phenotypes for erythromycin, ciprofloxacin, rifampicin or gentamicin. Among erythromycin-resistant MRSA strains, those with constitutive (macrolide and lincosamide) resistance are only 2-fold less sensitive as strains with inducible (14- and 15-membered macrolide only) resistance (MICs 0.5-1.0 and 0.25-1.0 mg/L, respectively). Quinupristin/dalfopristin is at least as active as vancomycin and more active than ciprofloxacin and erythromycin against MRSA. It generally has a more rapid bactericidal action than vancomycin and oxacillin against many strains of MRSA. The bactericidal activity of quinupristin/dalfopristin may be affected by macrolide resistance phenotype: S. aureus strains susceptible or inducibly resistant to macrolides are killed within 6 h, whereas a number of strains constitutively resistant to macrolides remain viable after 12 h. The clinical significance of this laboratory phenomenon requires investigation, possibly in additional animal models of infection.

Anti-Bacterial Agents↗
PubMed1997

Species identification of enterococci via intergenic ribosomal PCR.

Accurate species identification of enterococci has become important with the wide prevalence of acquired vancomycin resistance and the presence of less epidemiologically important, inherently vancomycin-resistant enterococci. Using a collection of enterococcal strains, we found that PCR amplification of the intergenic spacer (ITS-PCR) between the 16S and 23S rRNA genes can produce amplicon profiles characteristic of the enterococcus examined. The species examined were group I enterococci (Enterococcus avium, Enterococcus raffinosus, Enterococcus malodoratus, and Enterococcus pseudoavium), group II enterococci (Enterococcus faecalis, Enterococcus faecium, Enterococcus casseliflavus, Enterococcus mundtii, and Enterococcus gallinarum), and group III enterococci (Enterococcus durans and Enterococcus hirae). The enterococcal species in group I, as well as E. faecalis and two strains of E. hirae, were similar and therefore had to be differentiated from each other by Sau3A restriction digests. This produced patterns characteristic of each of these species. The remaining group II and group III enterococcal species produced amplicons characteristic of a particular species except E. gallinarum. The PCR products from E. gallinarum displayed strain-to-strain heterogeneity in the number and size of amplicons. To further test the utility of this technique, 11 phenotypically aberrant strains which had been assigned species identification based on Facklam and Collins-type strain reactions (R.R. Facklam and M.D. Collins, J. Clin. Microbiol. 27:731-734, 1989) were subjected to ITS-PCR. ITS-PCR of the phenotypically aberrant strains identified six strains with reactions consistent with those of type strains. However, five strains were characterized as follows: two strains originally identified as E. mundtii were identified by ITS-PCR as E. casseliflavus, one strain originally identified as E. raffinosus was identified by ITS-PCR as E. durans, one strain originally identified as E. hirae was identified by ITS-PCR as E. faecium [corrected]. We conclude that amplification of the intergenic 23S and 16S rRNA gene regions of enterococci provides a reliable technique for species identification of enterococci.

Bacterial Typing Techniques↗
PubMed1997

Prospective randomized trial of talc slurry vs bleomycin in pleurodesis for symptomatic malignant pleural effusions.

OBJECTIVE: Symptomatic malignant pleural effusions are common sequelae in patients with certain malignancies. Pleurodesis via bedside thoracostomy is the current treatment option most commonly used. To our knowledge, this is the first prospective randomized trial to examine which agent, bleomycin or talc slurry, is superior in terms of effectiveness, safety, and cost. PATIENTS AND METHODS: Between July 1992 and March 1995, 35 patients presenting to our medical center with symptomatic malignant pleural effusions were prospectively randomized to undergo chemical pleurodesis with either bleomycin or talc slurry via bedside thoracostomy. The conditions of patients were assessed and graded before and after treatment concerning pain, dyspnea, and chest radiographs. RESULTS: Twenty-nine patients who underwent 33 treatments (14 with bleomycin and 19 with talc) were available for follow-up. Follow-up ranged from 2 weeks to 8 months (mean, 1.7 months). Both groups demonstrated notable improvement in both pain and dyspnea following treatment, but there were no statistically significant differences between groups in the amount of improvement (two-tailed Student's t test). Permanent control of effusions, defined objectively on chest radiograph, was achieved with 11 bleomycin treatments (79%) and 17 talc treatments (90%) (p=0.388). The procedures were well tolerated and no significant adverse effects were observed. Talc is a much less costly agent than bleomycin ($12.36 cost to our medical center per treatment for talc vs $955.83 for bleomycin). CONCLUSION: Given the similar efficacy and significant cost advantage, we conclude that talc is the agent of choice when utilizing pleurodesis for control of symptomatic malignant pleural effusions.

Aged↗
PubMed1996

Streptococcal toxic shock syndrome in dogs.

OBJECTIVE: To determine the clinical, pathologic, and bacteriologic findings in dogs that developed severe invasive infections with group G streptococci (GGS) over a 6-month period in southern Ontario. DESIGN: Prospective case series. ANIMALS: 7 dogs n southern Ontario with severe streptococcal infection during a 6-month period. PROCEDURE: Using pulsed-field gel electrophoresis, molecular typing of streptococcal isolates was performed. Isolates were examined for the M protein gene emm1.0, pyrogenic exotoxin genes speA, speB, speF, hyaluronic acid synthase genes hasA, hasB, and for C5a peptidase gene scpA by use of DNA probes or polymerase chain reaction. RESULTS: 3 dogs with streptococcal shock without necrotizing fasciitis died or were euthanatized within 48 hours of admission, whereas 4 dogs with streptococcal shock and necrotizing fasciitis survived following surgical debridement, supportive medical treatment, and treatment with antibiotics. Of the 6 Lancefield group G streptococcal isolates available for characterization, 5 were Streptococcus canis and 1 had characteristics of group G streptococcal strains of human origin. Results of molecular typing indicated that isolates were unrelated to each other. Examination of the canine isolates for putative virulence genes found in human group A streptococci resulted in identification of the emm1.0 gene only in 1 of the isolates. The canine isolates otherwise lacked virulence genes associated with human group A streptococcal toxic shock infections. CLINICAL-IMPLICATIONS: The development of severe invasive infection in dogs resulting from GGS indicates that a virulent form of GGS has developed in southern Ontario.

Animals↗
PubMed1996

Invasive group A streptococcal infections in Ontario, Canada. Ontario Group A Streptococcal Study Group.

BACKGROUND: Several reports suggest that the incidence of invasive group A streptococcal infections, including streptococcal toxic shock syndrome and necrotizing fasciitis, is increasing. METHODS: During 1992 and 1993 we conducted prospective, population-based surveillance of invasive group A streptococcal disease in Ontario, Canada. We reviewed clinical and laboratory records, searched for secondary cases of invasive disease, and cultured specimens from household contacts. RESULTS: We identified 323 patients with invasive group A streptococcal infections, for an annual incidence of 1.5 cases per 100,000 population. The rates were highest in young children and the elderly. Fifty-six percent of the patients had underlying chronic illness. Risk factors for disease included infection with the human immunodeficiency virus, cancer, diabetes, alcohol abuse, and chickenpox. The most common clinical presentations were soft-tissue infection (48 percent), bacteremia with no septic focus (14 percent), and pneumonia (11 percent). Necrotizing fasciitis occurred in 6 percent of patients, and toxic shock in 13 percent. The mortality rate was 15 percent overall, but it was 29 percent among those over 64 years of age (P<0.001) and 81 percent among those with toxic shock (P<0.001). Fourteen percent of the cases were nosocomial, and 4 percent occurred in nursing home residents, often in association with disease outbreaks. Invasive disease occurred in 2 household contacts of patients with infection, for an estimated risk of 3.2 per 1000 household contacts (95 percent confidence interval, 0.39 to 12 per 1000). CONCLUSIONS: The elderly and those with underlying medical conditions are at greatest risk for invasive group A streptococcal disease, toxic shock, and necrotizing fasciitis. Invasive steptococcal infection is associated with a substantial risk of transmission in households and health care institutions.

Adolescent↗
PubMed1996

Plasma from patients with severe invasive group A streptococcal infections treated with normal polyspecific IgG inhibits streptococcal superantigen-induced T cell proliferation and cytokine production.

Previous studies have suggested a central role for superantigen-induced immune responses in the pathogenesis of streptococcal toxic shock syndrome. The production of streptococcal superantigens by clinical group A streptococcal (GAS) isolates was studied, and the ability of plasma collected from patients with severe invasive GAS infections to neutralize the proliferative- and cytokine-inducing activities of these superantigens was investigated. Overnight culture supernatants from all GAS isolates obtained from patients with invasive disease were found to contain superantigenic activity, as evident from their ability to drive potent T cell proliferation, induce high production of cytokines, and stimulate T cells in a V beta-specific manner. Twelve patients with severe invasive GAS infections, including 11 streptococcal toxic shock syndrome cases and one necrotizing fasciitis without shock, were treated with i.v. infusions of normal polyspecific Ig (IVIG). Plasma samples collected from each patient before and after IVIG administration were analyzed for their ability to neutralize the activity of streptococcal superantigens produced by the GAS isolate that caused their disease. In all IVIG-treated patients, the capacity to neutralize the superantigenic activity, produced by their respective GAS isolate or by purified streptococcal pyrogenic exotoxins, increased in plasma following IVIG administration. Of particular clinical relevance, post-IVIG plasma from each patient completely blocked cytokine production elicited by their respective GAS culture supernatants or by purified streptococcal pyrogenic exotoxins. This study shows that IVIG treatment confers in vivo inhibitory activity against a large array of streptococcal superantigens and suggests that IVIG may be useful in the treatment of severe invasive streptococcal infections.

Cytokines↗