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Donald E Low

Publications and source records attributed to Donald E Low.

At least 73 records · Page 4Linked to original sources
PubMed2003

Clinical and epidemiologic features of group a streptococcal pneumonia in Ontario, Canada.

BACKGROUND: Since the 1960s, group A streptococcus (GAS) has accounted for less than 1% of cases of community-acquired pneumonia. During the past 2 decades there has been a resurgence of invasive GAS infection, but no large study of GAS pneumonia has been performed. METHODS: To determine the clinical and epidemiologic features of GAS pneumonia, we conducted prospective, population-based surveillance of all invasive GAS infection in residents of Ontario from January 1, 1992, through December 31, 1999. RESULTS: Of 2079 cases of invasive GAS infection, 222 (11%) represented GAS pneumonia. The incidence of GAS pneumonia ranged from 0.16 per 100 000 in 1992 to 0.35 per 100 000 in 1999. Most cases were community acquired (81%). Forty-four percent of nursing home-acquired cases occurred during outbreaks. The case fatality rate was 38% for GAS pneumonia, compared with 12% for the entire cohort with invasive GAS infection and 26% for patients with necrotizing fasciitis. The presence of streptococcal toxic shock syndrome (odds ratio, 19; 95% confidence interval, 8.4-42; P =.001) and increasing age (odds ratio per decade, 1.45; 95% confidence interval, 1.2-1.7; P<.001) were associated with fatal outcome. Time to death was rapid, with a median of 2 days despite antimicrobial therapy and supportive measures. CONCLUSIONS: Group A streptococcal pneumonia is a common form of invasive GAS disease but remains an uncommon cause of community-acquired pneumonia. Progression is rapid despite appropriate therapy. The incidence is similar to, and the case fatality rate higher than, that of necrotizing fasciitis.

Chi-Square Distribution↗
PubMed2003

Risk factors for resistance to antimicrobial agents among nursing home residents.

The authors prospectively collected data on exposure to antimicrobial agents and susceptibility patterns among all clinical isolates of bacteria taken from 9,156 residents of 50 nursing homes in Canada and the United States in 1998-1999. Exposure to antimicrobial agents was measured during the 10 weeks prior to detection of targeted resistant bacteria in residents and compared with antibiotic exposure during a 10-week interval in individuals with sensitive organisms. These main effects were adjusted for infection-control and staffing covariates using multiple logistic regression modeling. Increased staffing of nursing homes with registered nurses (adjusted odds ratio (OR) = 0.79 (95% confidence interval (CI): 0.72, 0.87) per registered nurse per 100 resident-days) and use of antibacterial soap (adjusted OR = 0.40, 95% CI: 0.18, 0.90) were associated with reduced risk of methicillin-resistant Staphylococcus aureus in nursing home residents. An increase in the number of hand-washing sinks per 100 residents was shown to reduce the risk of trimethoprim-sulfamethoxazole (TMP/SMX)-resistant Enterobacteriaceae (adjusted OR = 0.94, 95% CI: 0.90, 0.98). Exposure to TMP-SMX and exposure to fluoroquinolones were significant risk factors for isolation of TMP-SMX-resistant Enterobacteriaciae (adjusted OR = 1.14, 95% CI: 1.06, 1.22) and fluoroquinolone-resistant Enterobacteriaciae (adjusted OR = 1.08, 95% CI: 1.04, 1.11), respectively. These findings suggest that increased staffing, more hand-washing sinks, and use of antimicrobial soap may reduce resistance to antimicrobial agents in long-term care facilities.

Anti-Bacterial Agents↗
PubMed2003

Serotypes of respiratory tract isolates of Streptococcus pneumoniae from Jamaican children.

BACKGROUND: Data are lacking on the pneumococcal serotypes present in many developing regions, including the Caribbean. We examined the serotypes of nasopharyngeal (NP) isolates of pneumococci obtained from Jamaican children. METHODS: We obtained NP samples from children seen in the Emergency Department at the Bustamante Children's Hospital. The samples were transported to Canada for isolation and serotyping of pneumococci. RESULTS: We obtained 94 isolates from 276 children; median age 3.4 years. The majority (57%) had symptoms of acute respiratory infection at the time of sampling. The main serotypes carried were 6B (20.5%), 19F (14.5%), and 14 (8.4%). Non-typable isolates accounted for 10.8% of the isolates. Fifty-nine per cent of the serotypes were present among the 11 being considered for candidate pneumococcal conjugate vaccines (95% CI 48-70%); the corresponding proportion present in the recently licensed 7-valent vaccine was 57% (95% CI 45-67%). A significant proportion of the serotypes found is absent from those to be included in future conjugate vaccines (P<0.0001; reference=85% expected serotype representation). Less than 5% of isolates were non-susceptible to penicillin (3.2%), cefotaxime-ceftriaxone (3.2%) and cefuroxime (3.2%), while 8.4% and 1.l% of isolates were resistant to trimethoprim-sulfamethoxazole and erythromycin respectively. There were three isolates with resistance to two or more classes of drug. These isolates were all resistant to penicillin (MIC 2 micro g/mL); the serotypes were 14, 23F, and 19F. CONCLUSION: A significant proportion of the serotypes found is absent from those to be included in future conjugate vaccines.

Adolescent↗
PubMed2003

Use of self-expandable metallic stents in benign GI diseases.

BACKGROUND: The self-expandable metallic stent is of proven benefit in patients with malignant disease; however, its use in patients with benign disease is not well established. There are few data available regarding long-term complications and outcomes with use of self-expandable metallic stents in benign disease and virtually none regarding attempted removal once the acute problem is resolved. METHODS: Thirteen patients who had a self-expandable metallic stent placed for benign GI disorders were included in a retrospective analysis. Data collected included patient demographics, indication for procedure, type of stent used, complications, and patient outcomes. RESULTS: Thirteen patients (7 women, 6 men; mean age 67 years, range 34-84 years) had one or more self-expandable metallic stents placed for benign disease and were followed for a mean of 3.4 years (3 weeks to 10 years). Of the 13 patients, 8 had esophageal stents, 4 biliary stents, and 1 had dual stents placed in the pancreaticobiliary tree. Complications developed in 8 (62%) patients; 4 (31%) ultimately died, either from the primary disease process (3) or from stent-related complications (1). CONCLUSIONS: Self-expandable metallic stent placement is effective treatment for benign esophageal leaks, providing the stent can be removed. It also may be used in either the esophagus or biliary tree in patients who are poor candidates for surgery and short expected survival. However, a self-expandable metallic stent should not be placed in a patient with a benign GI disorder who has a significant life expectancy and is a good candidate for surgery.

Adult↗
PubMed2003

Emergence of macrolide resistance in throat culture isolates of group a streptococci in Ontario, Canada, in 2001.

Of 500 group A streptococci isolated from pharyngeal swabs, 72 (14.4%) were macrolide resistant, compared to 2.1% in 1997. Of these, 66 (92%) were of the M phenotype and 6 (8.3%) were of the MLS phenotype. Pulsed-field gel electrophoresis found that two clones, with patterns identical to those of serotypes M1 and M4, accounted for 19.4 and 68.1% of the macrolide-resistant isolates, respectively.

Anti-Bacterial Agents↗
PubMed2003

Investigation of Staphylococcus aureus isolates identified as erythromycin intermediate by the Vitek-1 System: comparison with results obtained with the Vitek-2 and Phoenix systems.

We identified 69 Staphylococcus aureus isolates that were erythromycin intermediate as reported by the Vitek-1 system using the GPS-105 card. Of the 57 strains that were available for further testing, all were erythromycin resistant by broth microdilution and the Phoenix system, while the Vitek-2 system identified 55 of 57 strains (96%) as erythromycin resistant. The majority of isolates (54 of 57 [95%]) exhibited the inducible MLS (macrolide-lincosamide-streptogramin family) phenotype, as shown by the double-disk test. We recommend that all S. aureus strains determined as erythromycin intermediate by the Vitek-1 system be interpreted as resistant to erythromycin.

Anti-Bacterial Agents↗
PubMed2003

A comparison of bacteremic pneumococcal pneumonia with nonbacteremic community-acquired pneumonia of any etiology--results from a Canadian multicentre study.

BACKGROUND: Bacteremic pneumococcal pneumonia has not been the subject of a multicentre Canadian Study. OBJECTIVES: To compare bacteremic community-acquired Streptococcus pneumoniae pneumonia with nonbacteremic community-acquired pneumonia of any etiology. METHODS: A prospective cohort study was conducted at 15 centres in eight Canadian provinces from January 1996 to January 1998. RESULTS: Fifty-six of the 450 patients (12.4%) had one or more blood cultures positive for S pneumoniae. Compared with the 394 blood culture-negative patients, the bacteremic patients were younger (55.6 years versus 63.4 years; P=0.002). At presentation, bacteremic patients had a higher mean oral temperature (38.1+/-1.2 degrees C versus 37.7+/-1.2 degrees C; P=0.026), a higher pulse rate (108.4+/-22.1 beats/min versus 102.1+/-20.6 beats/min; P=0.033), a lower diastolic blood pressure reading (66.8+/-12.7 mmHg versus 73.8+/-15.8 mmHg; P=0.001) and a higher percentage of white blood cells that were band forms (22.1% versus 14.2%; P=0.0007). The time from onset of symptoms until admission to hospital was shorter among the bacteremic patients (4.6+/-3.7 days versus 7.0+/-13.9 days; P=0.005). Three capsular polysaccharide types accounted for 53.4% of the isolates: type 14, 29.2%; type 4, 12.1%; and type 22 F, 12.1%. Two of 44 isolates were resistant to penicillin. CONCLUSIONS: While some differences in patient characteristics and presentation occur when patients with bacteremic pneumococcal pneumonia are compared with nonbacteremic patients with community-acquired pneumonia, there is considerable overlap, and clinical presentation does not allow one to distinguish the bacteremic patients from the nonbacteremic patients.

Bacteremia↗
PubMed2003

Antimicrobial susceptibility breakpoints and first-step parC mutations in Streptococcus pneumoniae: redefining fluoroquinolone resistance.

Clinical antimicrobial susceptibility breakpoints are used to predict the clinical outcome of antimicrobial treatment. In contrast, microbiologic breakpoints are used to identify isolates that may be categorized as susceptible when applying clinical breakpoints but harbor resistance mechanisms that result in their reduced susceptibility to the agent being tested. Currently, the National Committee for Clinical Laboratory Standards (NCCLS) guidelines utilize clinical breakpoints to characterize the activity of the fluoroquinolones against Streptococcus pneumoniae. To determine whether levofloxacin breakpoints can identify isolates that harbor recognized resistance mechanisms, we examined 115 S. pneumoniae isolates with a levofloxacin MIC of >2 mg/mL for first-step parC mutations. A total of 48 (59%) of 82 isolates with a levofloxacin MIC of 2 mg/mL, a level considered susceptible by NCCLS criteria, had a first-step mutation in parC. Whether surveillance programs that use levofloxacin data can effectively detect emerging resistance and whether fluoroquinolones can effectively treat infections caused by such isolates should be evaluated.

Anti-Infective Agents↗
PubMed2002

An immunogenetic and molecular basis for differences in outcomes of invasive group A streptococcal infections.

The role of host genetic factors in conferring predisposition or protection in infectious diseases has become evident. Infection with group A streptococci causes a wide spectrum of disease ranging from pharyngitis to streptococcal toxic shock syndrome. The release of inflammatory cytokines triggered by streptococcal superantigens has a pivotal role in invasive streptococcal disease. However, individuals infected with the same strain can develop very different manifestations. We report here that the immunogenetics of the host influence the outcome of invasive streptococcal infection, and demonstrate the underlying mechanism for these genetic associations. Specific human leukocyte antigen class II haplotypes conferred strong protection from severe systemic disease, whereas others increased the risk of severe disease. Patients with the DRB1*1501/DQB1*0602 haplotype mounted significantly reduced responses and were less likely to develop severe systemic disease (P < 0.0001). We propose that human leukocyte antigen class II allelic variation contributes to differences in severity of invasive streptococcal infections through their ability to regulate cytokine responses triggered by streptococcal superantigens.

Fasciitis, Necrotizing↗
PubMed2002

Is surveillance for multidrug-resistant enterobacteriaceae an effective infection control strategy in the absence of an outbreak?

Multidrug-resistant enterobacteriaceae (MDRE) are an important cause of nosocomial infections. The effectiveness of screening for MDRE in the nonoutbreak setting in an attempt to prevent transmission is unknown. Patients admitted for new organ transplantation were screened for MDRE colonization. Prospective clinical data were collected, and pulsed-field gel electrophoresis and plasmid and integron analysis of isolates were performed. Colonized patients were not isolated except when required by standard precautions. Of the 287 patients, 69 (24%) were colonized, and 6 (9%) of the 69 developed clinical infections. Most colonizing isolates (66/69) were unique. No clinical infections resulted from patient-to-patient transmission. Analysis of clinical isolates from nonstudy patients demonstrated no evidence of transmission leading to clinical disease. The annual cost of a surveillance program was calculated at Canadian $1,130,184.44. Thus, the routine and costly use of MDRE surveillance and isolation precautions are not warranted in the absence of a clonal outbreak in this population.

Anti-Bacterial Agents↗
PubMed2002

The battle against emerging antibiotic resistance: should fluoroquinolones be used to treat children?

Inappropriate use of antibiotic drugs in humans and animals has led to widespread resistance among microbial pathogens. Resistance is the phenotypic expression corresponding to genetic changes caused by either mutation or acquisition of new genetic information. In some cases, multidrug resistance occurs. Streptococcus pneumoniae is one of the most important respiratory pathogens, playing a major role in both upper and lower respiratory tract infections. Pneumococcal resistance to antimicrobials may be acquired by means of horizontal transfer followed by homologous recombination of genetic material from the normal flora of the human oral cavity or by means of mutation. Resistance to penicillins and macrolides has been increasing for some time, but, recently, fluoroquinolone resistance has become an issue as well. We are concerned that, if fluoroquinolones are approved for use in children, their widespread use will result in rapid emergence of pneumococcal resistance, because children are more often colonized in the nasopharynx with high-density populations of pneumococci than are adults.

Anti-Bacterial Agents↗
PubMed2002

The impact of empirical management of acute cystitis on unnecessary antibiotic use.

BACKGROUND: Guidelines for the management of acute cystitis support empirical antibiotic treatment; however, up to half of symptomatic women have negative urine cultures. OBJECTIVE: To determine whether empirical treatment leads to unnecessary antibiotic prescriptions in women with symptoms of acute cystitis. METHODS: A cohort of 231 women (defined as females aged 16 years and older) presenting to family physicians' offices with symptoms of cystitis underwent a standardized clinical assessment, urine dip testing, and culture. Recommendations for urine testing and antibiotic treatment under 3 empirical strategies were compared with observed physician management and a logistic regression model for the outcomes of antibiotic prescriptions, urine culture testing, and unnecessary antibiotics, defined as a prescription where the subsequent urine culture was negative. RESULTS: There were 123 positive urine cultures (53.3%). Physicians prescribed antibiotics to 186 women (80.9%), of whom 74 (39.8%) were culture negative. Unnecessary antibiotic use was similar for 2 guidelines recommending empirical antibiotic treatment without testing for pyuria (41.4% and 40.6%). Treating women with classic cystitis symptoms and pyuria would have decreased unnecessary antibiotic use (26.2%; P =.02) but resulted in fewer women with confirmed urinary tract infection receiving immediate antibiotics (66.4% vs 91.8% usual care; P<.001). A derived prediction model incorporating testing for pyuria and nitrites would also have reduced unnecessary antibiotic use (27.5%; P =.03), but more women with confirmed urinary tract infection would have received immediate antibiotics (81.3%; P =.01). CONCLUSIONS: Empirical antibiotic treatment of acute cystitis in women without testing for pyuria promotes unnecessary antibiotic use. A simple decision rule provides for prompt treatment of infected women while reducing antibiotic overuse and unnecessary urine testing.

Acute Disease↗
PubMed2002

Severe group a streptococcal soft-tissue infections in Ontario: 1992-1996.

A prospective, population-based, surveillance study of invasive soft-tissue infections due to group A streptococci was conducted in Ontario, Canada, from 1992 through 1996. Demographic and clinical information was obtained by patient interview and chart review. Isolates were characterized by M protein and T agglutination typing. The incidence of necrotizing fasciitis (NF) increased from 0.08 cases per 100,000 population in 1992 to 0.49 cases per 100,000 population in 1995. The case-fatality rate was 13% (68 of 520 patients died). Hypotension and multiorgan dysfunction complicated 64 cases (12%), and NF complicated 119 cases (23%). Underlying diabetes, alcohol abuse, cancer, and cardiac and pulmonary disease increased the risk of disease. Prior use of nonsteroidal anti-inflammatory agents did not influence disease severity. All 197 patients without NF, underlying illness, and hypotension at presentation survived, as did 95 (99%) of 96 normotensive patients who were <65 years old but who had underlying chronic illness. Previously healthy patients without hypotension or NF may be considered for outpatient treatment.

Adolescent↗
PubMed2002

Effect of paraesophageal hernia repair on pulmonary function.

BACKGROUND: Paraesophageal hernias classically present in elderly patients with symptoms of postprandial pain, bloating, dysphagia, and anemia. Most surgeons would advocate repairing paraesophageal hernias whenever they are encountered, however, significant levels of dyspnea or pulmonary dysfunction could previously have led to concerns regarding individual patient suitability for repair. We have noted that patients complaining of dyspnea prior to paraesophageal hernia repair often noted significant improvement following surgery. METHODS: Between 1995 and 2001, 45 patients (mean age 71.5 years) presented with paraesophageal hernias. Patients had preoperative investigations including chest roentgenogram and barium swallow, 100%; upper endoscopy, 96%; manometry, 89%; and 24-hour pH studies, 27%. Operative repair was accomplished with an open Hill repair with intraoperative manometrics. All patients had assessment of pre- and postoperative spirometry, diffusion capacity, dyspnea index, and quality of life assessment. RESULTS: Presenting symptoms included dyspnea, 84%; heartburn, 71%; dysphagia, 67%; regurgitation, 64%; and anemia, 47%. Type II hernias were found in 2 patients, type III in 33 patients, and type IV in 10 patients. Complications were minimal; mortality was zero. Mean length of stay was 4.7 days (range 3 to 9). Significant improvement in spirometry levels were noted in mean forced expiratory volume in 1 second (FEV1) (preop, 1.87 liters; postop, 2.17 liters; percent improvement, 16%), p < 0.0001; mean forced vital capacity (FVC) (preop, 2.52 liters; postop, 2.89 liters; percent improvement, 14.7%), p < 0.0001; mean percent predicted FEV1 (preop, 75.8%; postop, 88.6%), p < 0.0001; and mean percent predicted FVC (preop, 78.8%; postop, 91.5%), p < 0.0001. An improvement trend was noted in diffusing capacity, which did not reach statistical significance. The degree of improvement was seen to correlate with the size of the hernia. When hernias involved 100% of the stomach, percent improvement in FEV1 of 19.6% and FVC of 19.7% were noted. Two patients who required home oxygen were able to discontinue therapy following surgery. Significant improvements in quality of life scores and dyspnea index were documented. CONCLUSIONS: Elderly patients with paraesophageal hernias are occasionally considered inappropriate candidates for surgical repair on the basis of coexistent medical problems including pulmonary dysfunction. Paraesophageal hernia repair is routinely associated with significant improvement in spirometry values, dyspnea index, and quality of life scores.

Aged↗
PubMed2002

Treatment of acute bacterial conjunctivitis: 1% fusidic acid viscous drops vs. 0.3% tobramycin drops.

BACKGROUND: A frequent cause of conjunctivitis is an acute bacterial infection, presenting with mucopurulent discharge and conjunctival hyperemia. The authors compared the clinical and microbiologic efficacy, safety and acceptability of 1% fusidic acid viscous drops (Fucithalmic) with 0.3% tobramycin ophthalmic solution (Tobrex) in the treatment of suspected bacterial conjunctivitis. METHODS: Patients were recruited at 20 sites in Ontario, Saskatchewan and Alberta from October 1995 to December 1998. Patients who presented to their primary care physician with suspected bacterial conjunctivitis, as identified by conjunctival hyperemia and purulent or mucopurulent discharge, were eligible for the study. Patients were randomly assigned to receive 7 days of treatment with either 1% fusidic acid (one drop applied twice daily) or 0.3% tobramycin (one to two drops applied four to six times daily). The investigators were blinded as to treatment status. Bacteriologic samples were taken from the inferior conjunctival cul-de-sac on day 0 and at the end of treatment. Signs and symptoms of conjunctivitis were assessed at baseline and after 3 and 7 days of treatment. The acceptability of treatment was assessed by having the patient or the parent or guardian complete a questionnaire on degree of compliance and ease of use after 3 and 7 days of treatment. RESULTS: Conjunctival swabs were obtained from 484 patients (410 over 9 years of age and 74 aged 2 to 9 years) to determine baseline bacteriology. Of the 484, 319 (65.9%) (63% of the older patients and 80% of those aged 2 to 9 years) had positive results of culture for bacteria. Ninety-four patients (19%) (63 [15%] of the older patients and 31 [42%] of those aged 2 to 9 years) had per-protocol pathogens as defined by quantitative bacteriology criteria. There was a direct correlation between the presence of mucopurulent discharge and the presence of per-protocol pathogens. There were no significant differences in clinical or bacteriologic efficacy between the treatment groups. Treatment compliance was similar between the treatment groups for the older patients; however, for those aged 2 to 9 years, compliance was significantly better in the fusidic acid group than in the tobramycin group (85% vs. 47%) (p < 0.001). Significantly more patients in the fusidic acid group than in the tobramycin group rated treatment as convenient or very convenient, particularly among younger patients (97% vs. 54%) (p < 0.001). INTERPRETATION: The clinical and bacteriologic efficacy of fusidic acid viscous drops combined with the convenience of a twice-daily dosage regimen establishes this antibiotic as first-line treatment for suspected acute bacterial conjunctivitis and a favourable alternative to other broad-spectrum antibiotics.

Adolescent↗