Molecular epidemiology of vancomycin-resistant enterococcal bacteraemia: results from the Canadian Nosocomial Infection Surveillance Program, 1999-2009.

OBJECTIVES: Vancomycin-resistant enterococci (VRE) can be associated with serious bacteraemia. The focus of this study was to characterize the molecular epidemiology of VRE from bacteraemia cases that were isolated from 1999 to 2009 as part of Canadian Nosocomial Infection Surveillance Program (CNISP) surveillance activities. METHODS: From 1999 to 2009, enterococci were collected from across Canada in accordance with the CNISP VRE surveillance protocol. MICs were determined using broth microdilution. PCR was used to identify vanA, B, C, D, E, G and L genes. Genetic relatedness was examined using multilocus sequence typing (MLST). RESULTS: A total of 128 cases of bacteraemia were reported to CNISP from 1999 to 2009. In 2007, a significant increase in bacteraemia rates was observed in western and central Canada. Eighty-one of the 128 bacteraemia isolates were received for further characterization and were identified as Enterococcus faecium. The majority of isolates were from western Canada (60.5%), followed by central (37.0%) and eastern (2.5%) Canada. Susceptibilities were as follows: daptomycin, linezolid, tigecycline and chloramphenicol, 100%; quinupristin/dalfopristin, 96.3%; high-level gentamicin, 71.6%; tetracycline, 50.6%; high-level streptomycin, 44.4%; rifampicin, 21.0%; nitrofurantoin, 11.1%; clindamycin, 8.6%; ciprofloxacin, levofloxacin and moxifloxacin, 1.2%; and ampicillin, 0.0%. vanA contributed to vancomycin resistance in 90.1% of isolates and vanB in 9.9%. A total of 17 sequence types (STs) were observed. Beginning in 2006 there was a shift in ST from ST16, ST17, ST154 and ST80 to ST18, ST412, ST203 and ST584. CONCLUSIONS: The increase in bacteraemia observed since 2007 in western and central Canada appears to coincide with the shift of MLST STs. All VRE isolates remained susceptible to daptomycin, linezolid, chloramphenicol and tigecycline.

The role of torovirus in nosocomial viral gastroenteritis at a large tertiary pediatric centre.

OBJECTIVE: To describe the viral etiology and epidemiology of nosocomial viral gastroenteritis (NVG) at a tertiary care pediatric hospital and identify any changes over the past two decades. METHODS: Retrospective review of all patients with laboratory-confirmed NVG at The Hospital for Sick Children (Toronto, Ontario), from January 1, 2004, to December 31, 2005. RESULTS: One hundred forty-two episodes of NVG were found among 133 patients, occurring in 0.48 of 100 admissions. The median age was two years; 42% were <1 year of age and 41% were immunocompromised. The most commonly detected pathogen was torovirus (67% of episodes), followed by rotavirus (19%) and adenovirus (9%). Seventy-five cases (53%) were epidemiologically linked in 32 separate clusters (median cluster size two, range two to four). The NVG rate fell from 0.63 of 100 to 0.22 of 100 admissions after March 2005 (P<0.001) when enhanced infection control precautions were instituted in response to an outbreak of vancomycin-resistant Enterococcus. CONCLUSIONS: Torovirus remains the most commonly identified cause of NVG at The Hospital for Sick Children. Most NVG cases were epidemiologically linked, and a significant reduction in cases occurred after the institution of enhanced infection control practices following an outbreak of vancomycin-resistant Enterococcus. Improved education and surveillance for NVG should lead to further reduction in this problem.

HISTORIQUE: Les chercheurs ont effectué la présente étude pour décrire l'étiologie virale et l'épidémiologie de la gastroentérite virale nosocomiale (GVN) dans un hôpital de pédiatrie tertiaire et déterminer les changements constatés depuis vingt ans. MÉTHODOLOGIE: Analyse rétrospective de tous les patients ayant une GVN confirmée en laboratoire à The Hospital for Sick Children (HSC) de Toronto, en Ontario, entre le 1er janvier 2004 et le 31 décembre 2005. RÉSULTATS: Les chercheurs ont retracé 142 épisodes de GVN chez 133 patients, dans 0,48 pour 100 des admissions. Ils avaient un âge médian de deux ans, 42 % avaient moins d'un an et 41 % étaient immunocompromis. Le torovirus était le pathogène le plus décelé (67 % des épisodes), suivi du rotavirus (19 %) et de l'adénovirus (9 %). Soixante-quinze cas (53 %) étaient liés à 32 grappes distinctes (grappe médiane de deux, plage de deux à quatre) sur le plan épidémiologique. Le taux de GVN a fléchi de 0,63 à 0,22 pour 100 des admissions après le 5 mars 2005 (P<0,001), lorsqu'on a renforcé les précautions de contrôle des infections en réponse à une épidémie d'entérocoques résistant à la vancomycine (ERV). CONCLUSIONS: Le torovirus demeure la principale cause de GVN diagnostiquées à l'HSC. La plupart des cas de GVN étaient liés sur le plan épidémiologique, et on a constaté une importante diminution du nombre de cas après le renforcement des pratiques de contrôle des infections découlant d'une éclosion d'ERV. Une meilleure éducation et une plus grande surveillance à l'égard du GVN devraient favoriser l'atténuation plus marquée de ce problème.

Transmission of Mycobacterium tuberculosis from an infant.

SETTING: This report investigates the unusual transmission of Mycobacterium tuberculosis from a 12-week-old infant with nosocomially acquired tuberculosis (TB). Compliance with recommendations on the post-exposure management of young children is described. DESIGN: Contacts of an infant case of TB were identified and recommended to undergo baseline and post-exposure tuberculin skin tests (TST) as per Canadian TB standards. TST conversion was measured at least 8 weeks post exposure. Children aged <6 years were recommended to initiate preventive treatment with isoniazid (INH) until their post-exposure TST. Information on TST results and adherence to therapy were analysed from existing medical records. RESULTS: Overall, 17 TST conversions were documented among 732 contacts: both parents, two health care workers (HCWs) who provided close care, and several patients, visitors and one staff member without obvious close contact. Of 65 eligible children, 46% completed post-exposure therapy as recommended. The most common reasons for treatment failure were concern about side effects, perception of low risk and lack of physician support. CONCLUSION: This investigation suggests that all children, including infants, with cough and numerous bacilli or extensive pulmonary disease should be considered infectious. Health care provider education is necessary to resolve the observed low compliance with current post-exposure management guidelines.

Comparison of throat swabs and nasopharyngeal suction specimens in non-sputum-producing patients with cystic fibrosis.

Both throat swabs and nasopharyngeal suction (NPS) specimens are used for microbiological assessment in non-sputum-producing patients with cystic fibrosis (CF), but studies comparing their diagnostic yield are lacking. We, therefore, conducted a prospective study in young CF patients, in which both techniques were performed in random order. Forty-seven consecutive CF children aged 6 months to 10 years were studied during routine visits to the clinic. CF relevant pathogens were found in the majority of patients with no significant differences in the rate of positive cultures for Staphylococcus aureus, Haemophilus influenzae, or Pseudomonas aeruginosa. A statistically significant difference was observed in the rate of detection of other organisms with only 9/47 (19%) of throat swab specimens and 27/47 (57%) of NPS specimens being positive (P = 0.0004). This included 12 positive cultures for Streptococcus pneumoniae and 11 cultures that were positive for Moraxella catarrhalis, both of which are frequent colonizers of the upper airway. Therefore, the most common bacterial pathogens affecting the CF lung appear to be detected in similar frequency by throat swab as by nasopharyngeal suction. There is evidence that nasopharyngeal suction yields more specimens of Streptococcus pneumoniae and Moraxella catarrhalis, which may reflect upper airway colonization rather than lower airway infection. We conclude that nasopharyngeal suction is not routinely warranted as there is no benefit over throat swab in detection of CF pathogens in infants and young children with CF.

Hyperviscosity syndrome in a patient with acquired immunodeficiency syndrome.

The hyperviscosity syndrome is most commonly seen in association with monoclonal gammopathies and has only rarely been described in association with polyclonal hypergammaglobulinemia. We have recently seen a patient with known acquired immunodeficiency syndrome who presented with the hyperviscosity syndrome in the setting of polyclonal hypergammaglobulinemia. To our knowledge, this is the first reported case of a patient with the acquired immunodeficiency syndrome and the hyperviscosity syndrome. The case is presented and the pathogenesis and implications of this diagnosis are discussed.

Complications associated with Ommaya reservoirs in patients with cancer. The Princess Margaret Hospital experience and a review of the literature.

The complications associated with the use of Ommaya reservoirs in 106 patients with meningeal involvement due to malignant disease are reviewed. Twenty-seven patients had acute lymphoblastic leukemia, 12 acute myelogenous leukemia, 3 chronic lymphocytic leukemia, 34 lymphoma, 29 carcinoma, and 1 chronic myelocytic leukemia. There were 11 technical complications, including 1 death due to misplacement of the catheter, 2 mild intraventricular hemorrhages, and 5 malfunctioning reservoirs; 3 required craniotomies (1 for subdural hematoma and 2 for subdural hygroma); 13 cases of bacterial meningitis occurred in 10 patients. One patient died of Staphylococcus aureus meningitis. The organisms causing the other infections were mainly coagulase-negative staphylococci (8 cases) or Propionibacterium acnes (2 cases). The projected infection rate for all patients (by Kaplan-Meier analysis) during the first year following insertion of a reservoir was 15%. Successful use of Ommaya reservoirs requires expert surgical implantation and meticulous care during accessing to minimize complications.

Hepatic candidiasis: an increasing problem in immunocompromised patients.

Hepatic candidiasis has been increasingly recognized as a variant of disseminated candidiasis in immunocompromised patients. Five leukemic patients with antemortem diagnosis of hepatic candidiasis are described, and 32 additional cases reported in the literature are reviewed. Cultures of the liver and/or spleen and blood cultures usually give negative results; histopathologic demonstration of Candida organisms in tissue specimens is necessary for a definitive diagnosis. Response to conventional therapy with amphotericin B is poor, and 34.4 percent of the patients died with evidence of active fungal disease. Liposome-encapsulated amphotericin B, which has been successfully used in a limited number of patients with invasive fungal disease, may be an effective and relatively nontoxic drug.

An endemic strain of Staphylococcus haemolyticus colonizing and causing bacteremia in neonatal intensive care unit patients.

Coagulase-negative staphylococci are now the major cause of bacteremia in neonatal intensive care units. To date, coagulase-negative staphylococci causing neonatal infections have been found to be distinct when typed by standard techniques. To determine whether or not an endemic strain could be identified using more discriminatory techniques, we characterized coagulase-negative staphylococci isolates obtained from a prospective study of coagulase-negative staphylococci bacteremia in a neonatal intensive care unit during 1984 through 1985, by standard techniques supplemented with DNA-DNA hybridization and restriction endonuclease analysis. We typed 58 strains that were isolated from 52 episodes of bacteremia in 38 neonates. There were 46 isolates of Staphylococcus epidermidis. Three pairs of strains were identical, and each strain was from a different patient. There were 12 isolates of Staphylococcus haemolyticus. Ten were identical, referred to as strain TOR-35, and had been isolated from eight different infants. Characterization of strains obtained in 1986 from a prospective study of coagulase-negative staphylococci-colonizing neonates admitted to the same neonatal intensive care unit found the TOR-35 strain had colonized 6 of 17 neonates by day seven. A point prevalence survey of all neonates in the same neonatal intensive care unit in 1990 found 5 of 30 neonates to be colonized with the TOR-35 strain. Therefore, we were able to identify an endemic strain of S haemolyticus that caused multiple episodes of bacteremia during a 6-month period and remained present in the same environment for a 5-year period.

Nosocomial urinary tract infections at a pediatric hospital.

Although the epidemiology of nosocomial urinary tract infections (NUTIs) is well-described in the adult population, there is little information on children. We therefore reviewed all our patients with NUTIs, to determine their age, underlying diagnoses, microorganisms involved, use of catheters and secondary bacteremias. During a 2-year period at our institution, NUTIs accounted for 10% of all nosocomial infections (0.8 infections/100 admissions). Of 44,948 patients admitted during this period 0.7% (n = 318) acquired 351 episodes of NUTI. The patient ages ranged from 5 days to 21 years. The highest rates of NUTIs per ward (NUTI/100 admissions or transfers to the ward) were seen in the neonatal surgery (4.8), hematology/oncology (2.7), infant neurosurgery (2.1) and neonatal intensive care units (1.9). The most common organisms isolated were Escherichia coli (26%), Enterococcus sp. (15%), Pseudomonas sp. (13%), Klebsiella sp. (10%) and coagulase-negative Staphylococcus (9%). Catheterrelated infections accounted for 48% of all the NUTIs. Secondary bacteremia occurred rarely, with an incidence of 2.9% (n = 7). We conclude that NUTIs represent an important proportion (10%) of nosocomial infections in our population of hospitalized children, but secondary bacteremia is uncommon.

The use of Streptococcus pneumoniae nasopharyngeal isolates from healthy children to predict features of invasive disease.

BACKGROUND: The role of sampling nasopharyngeal carriage isolates of Streptococcus pneumoniae to determine characteristics of isolates causing invasive disease has not been established. METHODS: Data were compared from two 1995 studies of S. pneumoniae in Metropolitan Toronto and Peel Region (population, 3.1 million). The first was a prospective survey of nasopharyngeal (NP) carriage in child care centers. The second was a prospective surveillance for all cases of invasive disease. RESULTS: There were 545 NP S. pneumoniae isolates obtained from 532 children and 96 cases of invasive S. pneumoniae disease in children. The prevalences of reduced antibiotic susceptibility in the NP carriage and invasive studies, respectively, were: penicillin (16% vs. 11%, P=0.29); erythromycin (12% vs. 7%, P=0.25); and multiresistant (16% vs. 12%, P=0.34). The power to rule out a difference between the groups was <30% for each comparison. Trimethoprim/sulfamethoxazole resistance was more common in NP carriage isolates than invasive isolates (38% vs. 23%, P=0.02). Serotype 14 was more common in invasive isolates, whereas serogroup 6 was more common in NP carriage isolates. Antibiotic-resistant isolates were predominantly serogroups 6, 19 and 23 in both studies. CONCLUSIONS: Nasopharyngeal carriage isolates of S. pneumoniae reflect the antibiotic susceptibility rates of invasive isolates found in the same period for most antibiotics. However, even a large study like this may have limited power to detect a difference. The most common NP carriage serotypes are the same as the invasive isolates, although the rank order of specific serotypes is different. Routine surveys of S. pneumoniae NP carriage are not feasible because of the cost of serotyping and limited power of the observations, unless sample sizes are extremely large.

Apparent lower rates of streptococcal toxic shock syndrome and lower mortality in children with invasive group A streptococcal infections compared with adults.

Since 1985 there have been worldwide reports of increases in severe invasive Group A streptococcal (IGAS) infections. We reviewed the charts of all children with IGAS infections (defined as isolation of Group A streptococcus from a normally sterile site) presenting to our institution over a 7-year period (January, 1985, to December, 1991) and the literature. Streptococcal toxic shock syndrome required hypotension and multisystem organ involvement. Twenty-four patients (mean age, 4.96 +/- 4.4 years) were identified with IGAS infection. One patient (presenting in 1989) met the criteria for probable streptococcal toxic shock syndrome and none died. Eight of 19 Group A streptococcal isolates tested were streptococcal pyrogenic exotoxin (SPE) A producers, most (90%) had the speC gene and all had the speB gene and produced the toxin. No M or T type predominated. The low rates of streptococcal toxic shock syndrome and fatalities among children with IGAS infection are consistent with other pediatric but not with adult series. The apparent differences in outcome of IGAS between children and adults were not explained by the virulence factors we examined and may warrant further investigation.

Nosocomial acquisition of pertussis diagnosed by polymerase chain reaction.

Awareness is growing of the role of pertussis infection among adolescents and adults, and of the possibility of nosocomial transmission. However, pertussis remains difficult to diagnose. We report a case of nosocomially acquired pertussis in a healthcare worker, diagnosed by polymerase chain reaction. The high sensitivity and rapid turnaround time for this test is useful to confirm the diagnosis when advising a healthcare worker to refrain from working.

Nosocomial transmission of tuberculosis (TB) associated with care of an infant with peritoneal TB.

Nosocomial transmission of tuberculosis (TB) after exposure to infected peritoneal fluid has not been described. We report the exposure of 111 healthcare workers to infected dialysate from an infant with TB peritonitis. Two (5%) of 39 primary-care nurses, but no doctors or environmental service workers, had apparent tuberculin skin test conversions, raising the concern that patients with peritoneal TB may be a source for nosocomial transmission of TB.

A randomized trial of 72- versus 24-hour intravenous tubing set changes in newborns receiving lipid therapy.

OBJECTIVE: To compare the microbial contamination rate of infusate in the intravenous tubing of newborns receiving lipid therapy, replacing the intravenous delivery system at 72-hour versus 24-hour intervals. DESIGN: Infants requiring intravenous lipid therapy were randomly assigned to have intravenous sets changed on a 72- or a 24-hour schedule, in a 3:1 ratio, in order to compare the infusate contamination rates in an equivalent number of tubing sets. SETTING: A 35-bed, teaching, referral, neonatal intensive-care unit (NICU). PARTICIPANTS: All neonates admitted to the NICU for whom intravenous lipid was ordered. METHODS: Patients were randomized in pharmacy, on receipt of the order for intravenous lipid therapy, to either 72- or 24-hour administration set changes, and followed until 1 week after discontinuation of lipids or discharge from the NICU. Microbial contamination of the infusate was assessed in both groups at the time of administration set changes. Contamination rates were analyzed separately for the lipid and amino acid-glucose tubing sets. Patient charts were reviewed for clinical and epidemiological data, including birth weight, gestational age, gender, age at start of lipid therapy, duration of parenteral nutrition, and type of intravenous access. RESULTS: During the study period, 1,101 and 1,112 sets were sampled in the 72- and 24-hour groups, respectively. Microbial contamination rates were higher in the 72-hour group than the 24-hour group for lipid infusions (39/1,101 [3.54%] vs 15/1,112 [1.35%]; P=.001) and for amino acid infusions (12/1,093 [1.10%] vs 4/1,103 [0.36%]; P=.076). Logistic regression analysis controlling for birth weight, gestational age, and type of venous access showed that only the tubing change interval was significantly associated with lipid set contaminations (odds ratio, 2.69; P=.0013). The rate of blood cultures ordered was higher in the 72- versus the 24-hour group (6.11 vs 4.99 per 100 patient days of total parenteral nutrition; P=.017), and a higher proportion of infants randomized to the 72-hour group died (8% vs 4%; P=.05), although the excess deaths could not clearly be attributed to bacteremia. CONCLUSION: Microbial contamination of infusion sets is significantly more frequent with 72- than with 24-hour set changes in neonates receiving lipid solutions. This may be associated with an increased mortality rate.

Nosocomial salmonellosis: implications for microbiologic processing of stools in hospitalized patients.

Many microbiology laboratories are rationalizing their services and are not culturing stool for bacterial and parasitic pathogens from patients hospitalized for more than 3 days. We report a sporadic case of nosocomial salmonellosis that highlights the need for ongoing communication among clinicians, infection control personnel, and laboratories to allow for modification of such a routine laboratory protocol should epidemiologic evidence warrant.

Contamination of intravenous fluid with Sporothrix schenckii.

Fungi are known to contaminate intravenous (IV) solutions, particularly when there is a defect in the bottle or bag. On occasion several millilitres of such solutions have been infused into patients before the recognition of clumps in the fluid led to termination of the infusion. We wish to report the case of a patient accidentally infused with 100 ml of a solution that on subsequent culture yielded both Penicillium species, a previously recorded contaminant, and Sporothrix schenckii, a recognised pathogen. To our knowledge, this is the first report of an IV solution contaminated with S. schenckii.

Ureaplasma urealyticum infections in the perinatal period.

Good evidence indicates the widespread carriage of U. urealyticum among sexually active females. Colonization of the upper genital tract appears to be a risk factor for adverse pregnancy outcomes, though this is not the case for lower-genital-tract colonization. Based on studies in which amniotic fluid obtained from amniocenteses was already positive for U. urealyticum, and its high prevalence in very-LBW neonates, it is likely that the infection is acquired during early pregnancy. A number of observational studies have linked this organism to pulmonary infections, meningeal infections, and bacteremias, particularly in LBW neonates. It is difficult, however, to separate the morbidity that is directly attributable to infection with the organism from morbidity owing to extreme prematurity. Problems in measuring the burden of illness resulting from this organism are compounded by difficulties in its diagnosis. The organism's fastidious nature prevents many laboratories from isolating it from specimens. Rapid and practical methods for identifying the organism are urgently needed. These need to be followed by RCTs to determine if outcomes of pregnant women and babies with various conditions, from whom the organism has been isolated, can be improved through treatment with antimicrobial agents.

Cotrimoxazole-resistant Escherichia coli bacteremia in neutropenic patients at a regional oncology hospital.

In a regional oncology hospital using cotrimoxazole (trimethoprim-sulphamethoxazole) prophylaxis during chemotherapy-induced neutropenia, a single strain of Escherichia coli (indole negative) caused 15 of 27 episodes of Gram-negative rod bacteremia in 1987, and four of 32 such episodes in 1988. This biotype had not been recovered in 1986. Investigations during this 'outbreak' of bacteremias revealed enteric colonization with this strain of E coli in 37% of patients on leukemia or bone marrow transplant wards and in several staff members in July 1987. In 1988, 11 of 32 Gram-negative rod bacteremias were secondary to other strains of indole positive E coli of several different biotypes and plasmid profiles. Indole negative strains all exhibited low level trimethoprim resistance, whereas indole positive strains which subsequently appeared exhibited high level trimethoprim resistance. Failure of cotrimoxazole prophylaxis was initially due to the clonal dissemination of a single strain of E coli within the institution, with the subsequent appearance of multiple E coli strains with probable differing genetic bases for their resistance.

Molecular epidemiological characterization of respiratory isolates of Moraxella catarrhalis in a pediatric intensive care unit.

A perceived increase in the number of isolates of Moraxella catarrhalis from the respiratory secretions of patients intubated in the pediatric intensive care unit prompted a review of the clinical profiles of such patients and restriction enzyme analysis of the strains involved. Over two months, of 192 patients admitted to the unit, 154 were intubated. Of the 46 for whom endotracheal tube specimens were submitted to the laboratory, M catarrhalis was isolated in 12. M catarrhalis was not felt to be a significant respiratory pathogen by the attending medical staff in any of the patients from whom it was isolated. In only two patients (17%) could nosocomial acquisition be firmly invoked. Restriction enzyme analysis of the 12 strains ruled out the presence of an epidemic strain. Isolation of M catarrhalis from intubated children does not necessarily imply pathogenicity nor an outbreak situation.

The emerging epidemiology of VRE in Canada: results of the CNISP Passive Reporting Network, 1994 to 1998.

OBJECTIVE: To provide a rapid and efficient means of collecting descriptive epidemiological data on occurrences of vancomycin-resistant enterococcus (VRE) in Canada. DESIGN AND METHODS: Passive reporting of data on individual or cluster occurrences of VRE using a one-page surveillance form. SETTING: The surveillance form was periodically distributed to all Canadian Hospital Epidemiology Committee members, Community and Hospital Infection Control Association members, L'Association des professionnels pour la prevention des infections members and provincial laboratories, representing 650 health care facilities across Canada. PATIENTS: Patients colonized or infected with VRE within Canadian health care facilities. RESULTS: Until the end of 1998, 263 reports of VRE were received from 113 health care facilities in 10 provinces, comprising a total of 1315 cases of VRE, with 1246 cases colonized (94.7%), 61 infected (4.6%)and eight of unknown status. (0.6%). VRE occurrences were reported in 56% of acute care teaching facilities and 38% of acute care community facilities. All facilities of more than 800 beds reported VRE occurences compared with only 10% of facilities with less than 200 beds (r2=0.86). Medical and surgical wards accounted for 51.4% of the reported VRE occurences. Sixty-five (24.7%) reports indicated an index case was from a foreign country, with 85.2% from the United States and 14.8% from other countries. Some type of screening was conducted in 50% of the sites. CONCLUSIONS: A VRE passive reporting network provided a rapid and efficient means of providing data on the evolving epidemiology of VRE in Canada.