Peter Jessamine

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.

The presence of serum antibody to the chlamydial heat shock protein (CHSP60) as a diagnostic test for tubal factor infertility

OBJECTIVE To study the utility of testing for heat shock protein 60 (CHSP60) antibodies in the diagnosis of tubal factor infertility. DESIGN Prospective case control. SETTING Canadian university hospital infertility clinic. PATIENT(S) Women presenting for infertility investigation. INTERVENTION(S) Sera were collected from 77 patients. MAIN OUTCOME MEASURE(S) The relationship between tubal factor infertility and the presence of antibodies to Chlamydia trachomatis and CHSP60 was assessed. RESULT(S) There were no significant differences between antibodies to C. trachomatis in women with tubal factor infertility (63%) and other causes of infertility (46%). However, more women with tubal factor infertility (44%) had anti-CHSP60 antibodies compared with other causes of infertility (8%). Antibody testing for C. trachomatis has only a 63% sensitivity and a 54% specificity for detecting tubal factor infertility. In contrast, the CHSP60 antibody test has a 44% sensitivity and a 92% specificity for detecting tubal factor infertility. There is a good positive likelihood ratio of 5.5 for CHSP60 antibody testing detecting the presence of tubal factor infertility. Combining CHSP60 antibody with antibody testing for C. trachomatis has an excellent positive likelihood ratio of 10 for the detection of C. trachomatis-associated tubal factor infertility. CONCLUSION(S) CHSP60 antibody testing is a more accurate test than antibody testing for C. trachomatis for predicting chlamydia-associated tubal factor infertility. These tests, when used in combination at initial infertility evaluation, would provide a rapid noninterventive means of diagnosing tubal factor infertility.

Detection of Plasmid-Mediated KPC-Producing Klebsiella pneumoniae in Ottawa, Canada: Evidence of Intrahospital Transmission

ABSTRACT Klebsiella pneumoniae isolates from three patients admitted to the Ottawa Hospital, a 1,040-bed teaching hospital, were found to contain the plasmid-borne K. pneumoniae carbapenemase (KPC)-producing bla gene (blaKPC). There was evidence of person-to-person transmission for two patients. Screening of 186 clinical isolates revealed no additional blaKPC-containing isolates.

An Evaluation of the Management of Asymptomatic Catheter-Associated Bacteriuria and Candiduria at The Ottawa Hospital

BACKGROUND Asymptomatic catheter-associated urinary tract infections (CAUTIs) are common in hospitalized patients. They are associated with a low incidence of sequelae and morbidity, and in most patients resolve spontaneously on removal of the catheter. As a result, it is not recommended that asymptomatic catheter-associated bacteriuria or candiduria be treated with antimicrobial agents while the catheter remains in place because it may lead to the evolution of resistant flora. OBJECTIVE To assess the current management of patients with CAUTIs with respect to antimicrobial therapy at The Ottawa Hospital and the University of Ottawa Heart Institute, Ottawa, Ontario. METHODS A prospective observational study over a period of 26 consecutive days was conducted at The Ottawa Hospital (General and Civic campuses) and the University of Ottawa Heart Institute. Inpatients with an indwelling catheter, a positive urine culture and the absence of UTI signs or symptoms were assessed. Patients were followed for five days to determine whether antimicrobials were prescribed. RESULTS From March 3 to March 28, 2003, 29 of 119 patients screened met inclusion criteria. Of these 29 patients, 15 (52%) were prescribed antimicrobials and were therefore considered to be inappropriately managed. Differences were observed between the appropriate and inappropriate management groups in terms of duration of stay to positive urine culture and whether yeast or bacteria were isolated from the culture. CONCLUSION Antimicrobial agents were prescribed in over one-half of CAUTI cases, contrary to recommendations from the literature. Education is required to bring this strongly supported recommendation into clinical practice.

Hospital-Acquired Invasive Group A Streptococcal Infections in Ontario, Canada, 1992–2000

BACKGROUND A significant proportion of invasive group A streptococcal infections are hospital acquired. No large, prospective studies have characterized this subgroup of cases and evaluated the risk of transmission in hospitals. METHODS We conducted prospective, population-based surveillance of invasive group A streptococcal infections in Ontario, Canada, from 1992 to 2000. Epidemiologic and microbiologic investigations were conducted to identify cross-transmission. RESULTS We identified 291 hospital-acquired cases (12.4%) among 2351 cases of invasive group A streptococcal disease. Hospital-acquired invasive group A streptococcal infections are heterogeneous, including surgical site (96 cases), postpartum (86 cases), and nonsurgical, nonobstetrical infections (109 cases). Surgical site infections affected 1 of 100,000 surgical procedures and involved all organ systems. Postpartum infections occurred at a rate of 0.7 cases per 10,000 live births and exhibited an excellent prognosis. Nonsurgical, nonobstetrical infections encompassed a broad range of infectious syndromes (case-fatality rate, 37%). Nine percent of cases were associated with in-hospital transmission. Transmission occurred from 3 of 142 patients with community-acquired cases of necrotizing fasciitis requiring intensive care unit (ICU) admission, compared with 1 of 367 patients with community-acquired cases without necrotizing fasciitis admitted to the ICU and 1 of 1551 patients with other cases (P<.001). Fifteen outbreaks were identified; 9 (60%) involved only 2 cases. Hospital staff were infected in 1 of 15 outbreaks, but colonized staff were identified in 6 (60%) of 10 investigations in which staff were screened. CONCLUSIONS Presentation of hospital-associated invasive group A streptococcal infections is diverse. Cross-transmission is common; illness occurs in patients but rarely in staff. Isolation of new cases of necrotizing fasciitis and intervention after a single nosocomial case may also prevent transmission.

Surveillance for hospital outbreaks of invasive group a streptococcal infections in Ontario, Canada, 1992 to 2000.

Context Hospital outbreaks of invasive group A streptococcal infection are a potentially preventable source of morbidity and mortality. Contribution In Ontario, Canada, 291 cases of hospital-acquired invasive group A infection occurred between 1992 and 2000; 10% of these infections occurred during 20 outbreaks in the hospital. Although nosocomial infections were most common in surgical and obstetric patients, most outbreaks of streptococcus A infection occurred outside of those settings. One quarter of the outbreaks was related to community-acquired infections (mostly necrotizing fasciitis) requiring intensive care; the bacteria were primarily transmitted from patient to patient. Implication Isolation of patients with necrotizing fasciitis may be an important strategy to reduce hospital outbreaks of invasive group A streptococcal infection. The Editors Streptococcus pyogenes has the capacity to produce myriad invasive diseases, the most dramatic being necrotizing fasciitis and streptococcal toxic shock syndrome (1). The rate of invasive disease has increased in recent decades to more than 3 per 100000 persons per year, and the case-fatality rate remains approximately 15% (2, 3). Equally as dramatic as the illness that group A streptococcus produces in individual patients are the outbreaks it has caused in hospitals (463). Such outbreaks have involved as many as 56 patients and health care workers and have continued for as long as 3 years (32, 39). Preventing hospital transmission of group A streptococcal infection would allow for the prevention of many secondary cases of disease (64). The current Centers for Disease Control and Prevention (CDC) recommendations for preventing nosocomial outbreaks exist only for postpartum and postsurgical settings and are based on expert opinion and a review of a limited number of outbreaks (6, 28, 32, 41, 55, 58, 65). This study sought to describe the epidemiology of hospital outbreaks of invasive group A streptococcal disease in Ontario, Canada, in order to assess the utility of proposed strategies for the prevention, investigation, and management of clusters of this disease (66). Methods Surveillance Prospective, population-based surveillance of all invasive group A streptococcal infections was conducted in the province of Ontario, Canada, from 1 January 1992 to 31 December 2000, as described elsewhere (2, 3). All Ontario microbiology laboratories processing sterile-site specimens telephoned the central study office whenever group A streptococcus was identified from a specimen from any sterile site. Annual audits were performed in all laboratories to ensure complete case ascertainment. Case definitions are described elsewhere (3). Invasive group A streptococcal infection was defined as illness associated with isolation of group A streptococcus from a normally sterile body site. Infections were deemed hospital acquired if disease was neither present nor incubating at the time of admission (67). The Ontario Group A Streptococcal surveillance system was approved by the institutional review boards of the University of Toronto and participating hospitals. Investigation of Disease Transmission When a nosocomial case of group A streptococcus was identified, study staff contacted the hospitals infection control practitioner to offer recommendations regarding investigation. Recommendations included 1) case finding in hospital patients, staff, and family members; 2) screening close contacts of the patient for symptoms of group A streptococcal infection; 3) taking additional precautions or restricting work for acutely ill contacts; 4) obtaining throat swabs and considering vaginal and rectal swabs from contacts for group A streptococcal culture; and 5) typing any isolates obtained. An outbreak was defined as the occurrence of at least 2 cases of culture-confirmed, symptomatic infection that were epidemiologically linked and were caused by isolates of the same M and T type and were indistinguishable by pulsed-field gel electrophoresis (3). Study staff were available for consultation during these investigations, and typing of isolates was provided by the study. Laboratory Methods Clinical isolates were identified as S. pyogenes using standard methods. Both M serotyping and T agglutination typing were performed at the Canadian National Centre for Streptococcus, Edmonton, Alberta, Canada (6870). Pulsed-field gel electrophoresis was performed as described elsewhere (71). Statistical Analysis Surveillance data were entered in duplicate and were analyzed in SAS for Windows, version 8 (SAS Institute, Cary, North Carolina). Differences in proportions were assessed by using Fisher exact tests, and differences in continuous variables were evaluated by using Wilcoxon rank-sum tests. Role of the Funding Sources Surveillance was funded by the CDC and by the Department of Microbiology at the Mount Sinai Hospital. These funding sources contributed to the design of surveillance but had no influence on the conduct or reporting of this study or the decision to submit the manuscript for publication. Results In prospective surveillance from 1 January 1992 to 31 December 2000, 2351 cases of invasive group A streptococcal disease were detected in Ontario (3) (Table 1). Of the 291 nosocomial invasive group A streptococcal infections, 29 (10%) were associated with 20 outbreaks. These 20 nosocomial outbreaks also involved 26 laboratory-confirmed noninvasive group A streptococcal illnesses, for a total of 53 outbreak-associated patient cases (there were 6 cases in health care workers, all pharyngitis). The average rate of outbreaks over the 9-year period was 1.0 per 100 hospitals per year, with an average rate of outbreak-associated disease of 0.5 per 100000 hospital admissions per year. Table 1. Characteristics of Invasive Group A Streptococcal Disease Cases in Ontario, 19922000 The clinical presentations of the 29 invasive cases associated with outbreaks did not differ from those of all invasive disease cases (data not shown). The case-fatality rate of outbreak-associated invasive cases (24% [7 of 29]) did not statistically significantly differ from that of all cases of invasive infection (16% [347 of 2242]; P= 0.20) or that of sporadic nosocomial infections (17% [42 of 255]; P> 0.2). Table 2 details the characteristics of the 20 nosocomial outbreaks. The outbreaks were distributed evenly over time and occurred in 15 institutions. Five (25%) outbreaks included at least 1 surgical site infection; 6 (30%) included at least 1 postpartum infection; and 14 (70%) included at least 1 nonsurgical, nonobstetric infection. Five (25%) outbreaks involved a mix of 2 or more case types. Nonsurgical, nonobstetric infections encompassed a broad range of syndromes, including primary bacteremia (5 cases), soft-tissue infection (5 cases), pneumonia (4 cases), pharyngitis (2 cases), and peritonitis (1 case). Table 2. Nosocomial Outbreaks of Group A Streptococcal Infection Identified via Prospective Surveillance in Ontario, 19922000 In 5 (25%) outbreaks, transmission was initiated by admission of a patient with community-acquired invasive group A streptococcal infection. All community-acquired index cases involved necrotizing fasciitis or a draining soft-tissue infection, and 4 of the 5 patients were admitted directly to an intensive care unit. Outbreak initiation and propagation were rapid, with a median interval between first and second cases of 4.5 days (range, 0 to 30 days) and a median interval between any 2 subsequent cases of 2 days (range, 0 to 11 days). Fourteen outbreaks (70%) involved only 2 cases. The largest outbreak involved 10 cases: 6 health care workers and 4 patients. Only 2 (10%) outbreaks lasted more than 2 weeks, and none lasted more than 1 month. The most common mode of outbreak propagation was patient-to-patient transmission (via a person or the environment), judged as primarily responsible for 12 (60%) outbreaks. Transmission from a staff carrier was the sole source of transmission in 1 (5%) outbreak, mixed patient-to-patient transmission and staff transmission contributed to 1 (5%) outbreak, and in 1 (5%) outbreak it could not be determined whether transmission occurred from a staff carrier or by patient-to-patient spread. The mode of propagation could not be ascertained in the remaining 5 (25%) outbreaks. Transmission via the inanimate environment was suspected in 2 situations. One patient developed group A streptococcal pneumonia 2 days after being admitted to the intensive care unit room and bed of a patient who had died of necrotizing fasciitis. No staff had contact with both patients. Another patient developed a postoperative surgical site infection 24 hours after having a biopsy in an operating room in which the previous procedure (completed 6 hours before) was debridement of necrotizing fasciitis. Again, no staff had contact with both patients. In 3 of the 11 (26%) remaining outbreaks thought to be propagated from patient to patient, roommates of index patients developed acute infection. The staff carrier implicated as a sole source was a colonized surgeon linked to 3 surgical site infections over a 10-day period. One colonized obstetrician was probably responsible for propagation of 2 of 3 secondary cases of postpartum disease in another outbreak, and 1 colonized nurse may have been responsible for propagation to 2 patients on a medical ward in a third outbreak. In 5 of 10 (46%) other investigated outbreaks, at least 1 colonized or infected staff person was identified; in all cases, a health care worker may have transmitted S. pyogenes to 1, but not more than 1, of the outbreak-associated cases. Although a staff carrier was the primary mode of transmission in only 2 (10%) outbreaks, 1 or more health care workers were colonized with the outbreak strain in 6 of 18 (33%) other outbreaks. In 5 outbreaks (25%), health care workers who were screened were colonized with nonoutbreak strains. In outbreaks

Does serologic evidence of remote Chlamydia trachomatis infection and its heat shock protein (CHSP 60) affect in vitro fertilization-embryo transfer outcome? * †

OBJECTIVE To examine IVF-ET outcome in patients with and without serologic evidence of Chlamydia trachomatis infection and chlamydia heat shock protein 60 (CHSP 60) antibodies. DESIGN Retrospective case control. SETTING University-affiliated IVF-ET program. MAIN OUTCOME MEASURES A total of 195 IVF-ET patients with tubal factor infertility underwent oocyte pick-up, 166 of these women had ET resulting in a total of 37 pregnancies. Serum antibody testing for evidence of remote C. trachomatis and CHSP 60, as well as pregnancy outcome, were determined for all patients. RESULTS There were no differences in pregnancy rates or outcomes between C. trachomatis seropositive versus seronegative groups: 27/118 (23%) C. trachomatis seropositive versus 10/77 (13%) C. trachomatis seronegative patients achieved pregnancy per oocyte pick-up. Pregnancy rates per ET were 27/105 (26%) in C. trachomatis seropositive versus 10/61 (16%) C. trachomatis seronegative patients. In the C. trachomatis positive subgroup, significantly higher pregnancy rates were found in the CHSP 60 antibody positive patients: 24/67 (36%) CHSP 60 positive versus 3/51 (6.0%) CHSP 60 negative patients were pregnant after oocyte pick-up (OR = 8.9, 95% CI = 2.3 to 27.5). Pregnancy rates per ET were 24/57 (42%) in CHSP 60 positive versus 3/48 (7%) CHSP 60 negative patients (OR = 10.9, 95% CI = 2.8 to 33.6). There were no significant differences in any group when examining the following pregnancy outcomes: spontaneous abortion, ectopic pregnancy, preterm and multiple pregnancy rates. CONCLUSIONS [1] There are no differences in pregnancy rates or outcomes in patients with and without serologic evidence of previous C. trachomatis infections. [2] In women seropositive for C. trachomatis, significantly higher pregnancy rates are found in women who are CHSP 60 antibody positive versus negative. [3] Pregnancy outcomes do not appear to be different between these groups.

Epidemiology of methicillin-resistant Staphylococcus aureus in three Canadian tertiary-care centers.

OBJECTIVE To describe the epidemiology and spread of methicillin-resistant Staphylococcus aureus (MRSA) in three tertiary-care centers in Ottawa, Ontario, Canada, where MRSA is encountered infrequently. DESIGN Retrospective review over a 6-year period, from January 1, 1990, through December 31, 1995. SETTING Three tertiary-care teaching hospitals in Ottawa. PARTICIPANTS Patients and healthcare workers (HCWs) with MRSA isolated from any body site. METHODS Patients and HCWs were identified retrospectively through hospital microbiology and infection control records. Patient charts were reviewed for clinical and epidemiological data, including age, gender, previous hospital admissions (where noted), and current and recent antibiotic use. MRSA isolates that were available were typed using pulsed-field gel electrophoresis (PFGE). Methicillin resistance was confirmed by standard methods and by polymerase chain reaction using mecA-specific primers. RESULTS MRSA was identified in 53 patients and 2 HCWs. Three patients were excluded from further analysis because medical records were incomplete. Epidemiological data were collected on the remaining 52 individuals. Thirty-nine isolates from 31 patients and 2 HCWs were available for PFGE typing. Five epidemiologically linked nosocomial clusters involving 10 patients and 2 HCWs were identified and were confirmed by PFGE. MRSA isolates from a sixth cluster were not available for PFGE. In each cluster, nosocomial spread was minimized by standard infection control practices, including strict isolation of patients and screening of contacts. There was no evidence of secondary spread of MRSA involving the remaining 36 patients. Recent antibiotic use, surgery, admission to an intensive-care unit, and previous hospitalization were common among patients. There was no evidence of spread of MRSA among the three hospitals, and no endemic strains were apparent in any of these centers. CONCLUSIONS MRSA remains an infrequent isolate in our centers, with no apparent interhospital spread. In institutions with little or no endemic MRSA, rigorous application of standard infection control practices is effective in limiting nosocomial transmission of this organism.

Detection of Methicillin Resistance in Coagulase-Negative Staphylococci Initially Reported as Methicillin Susceptible Using Automated Methods

Reliable detection of methicillin resistance in coagulase-negative staphylococci (CNS) is required for appropriate therapy of serious infections from these pathogens. To determine the most accurate method of measuring methicillin resistance in CNS initially reported as methicillin susceptible by automated methods, we compared mecA detection by polymerase chain reaction (PCR) with phenotypic methods. One hundred eighty-eight blood culture isolates of CNS that were initially reported as susceptible to methicillin using commercial methods (Vitek or MicroScan) were tested by agar dilution, disk diffusion, oxacillin salt agar screen plate, and a multiplex PCR assay using primer sets for mecA and 16S rRNA. Sixteen isolates (8.5%) previously reported as methicillin susceptible by automated methods contained the mecA gene. MICs of these isolates ranged from 0.5 microgram/mL to > or = 128 micrograms/mL. Ten of these isolates had MICs equal to or below the NCCLS breakpoint of 2 micrograms/mL. Six of the 10 isolates (4 with MICs of 0.5 microgram/mL and 2 with MICs of 2 micrograms/mL) did not grow on any of the oxacillin screen plates after 48 h of incubation at 30 degrees C or 35 degrees C. All six isolates were induced to grow in the presence of oxacillin at 128 micrograms/mL by serial passaging on plates containing increasing concentrations of antibiotic. Retesting with MicroScan and Vitek detected methicillin resistance in 7 and 10 isolates, respectively. Disk diffusion testing with incubation for 48 h proved to be the next best method after PCR for detection of methicillin resistance (15 of 16 isolates). Commercial automated methods and some methods recommended by National Committee for Clinical Laboratory Standards may not detect methicillin resistance in CNS that carry the mecA gene and have MICs just below breakpoint.

Positive bactec resin cultures do not influence antimicrobial selection

We performed a retrospective evaluation of Bactec resin blood cultures, submitted to the clinical laboratories of the University of Manitoba teaching hospitals, to determine the impact positive cultures might have on the selection of antimicrobial therapy. Of the 2919 resin cultures submitted in 1987, 151 were positive, with 161 separate isolates. Of these cultures, 13 were reported after the death of the patient and 8 could not be adequately assessed because of insufficient clinical information. Four positive cultures were obtained from patients not receiving antimicrobial therapy. Forty-four cultures (53 isolates) from 37 patients were judged to be contaminants. Each of the remaining 82 clinically significant positive cultures were monomicrobial. Isolates from 34 cultures were resistant to the antibiotics being administered and might have been expected to grow in nonresin blood cultures. Forty-eight isolates from 18 patients were susceptible to the antibiotic(s) being administered at the time the culture was drawn. In none of these patients did the positive result lead to a change in the choice of antimicrobial therapy. In only one case was there an increase in antibiotic dosage. It appears that positive Bactec resin blood cultures do not have a significant impact on antimicrobial selection, and routine use may not be justified.