ABSTRACT
BACKGROUND: Several Clostridium difficile infection (CDI) surveillance programs do not specify laboratory strategies to use. We investigated the evolution in testing strategies used across Quebec, Canada, and its association with incidence rates. METHODS: Cross-sectional study of 95 hospitals by surveys conducted in 2010 and in 2013-2014. The association between testing strategies and institutional CDI incidence rates was analyzed via multivariate Poisson regressions. RESULTS: The most common assays in 2014 were toxin A/B enzyme immunoassays (EIAs) (61 institutions, 64%), glutamate dehydrogenase (GDH) EIAs (51 institutions, 53.7%), and nucleic acid amplification tests (NAATs) (34 institutions, 35.8%). The most frequent algorithm was a single-step NAAT (20 institutions, 21%). Between 2010 and 2014, 35 institutions (37%) modified their algorithm. Institutions detecting toxigenic C difficile instead of C difficile toxin increased from 14 to 37 (P < .001). Institutions detecting toxigenic C difficile had higher CDI rates (7.9 vs 6.6 per 10,000 patient days; P = .01). Institutions using single-step NAATs, GDH plus toxigenic cultures, and GDH plus cytotoxicity assays had higher CDI rates than those using an EIA-based algorithm (P < .05). CONCLUSIONS: Laboratory detection of CDI has changed since 2010. There is an association between diagnostic algorithms and CDI incidence. Mitigation strategies are warranted.
Subject(s)
Clostridioides difficile/isolation & purification , Diagnostic Tests, Routine/trends , Enterocolitis, Pseudomembranous/diagnosis , Enterocolitis, Pseudomembranous/epidemiology , Immunoenzyme Techniques/statistics & numerical data , Polymerase Chain Reaction/statistics & numerical data , Aged , Bacterial Proteins/analysis , Bacterial Proteins/genetics , Bacterial Proteins/immunology , Bacterial Toxins/analysis , Bacterial Toxins/immunology , Clostridioides difficile/genetics , Clostridioides difficile/immunology , Cross-Sectional Studies , DNA, Bacterial/genetics , Enterocolitis, Pseudomembranous/microbiology , Enterocolitis, Pseudomembranous/pathology , Enterotoxins/analysis , Enterotoxins/immunology , Female , Glutamate Dehydrogenase/genetics , Humans , Immunoenzyme Techniques/methods , Incidence , Male , Middle Aged , Multivariate Analysis , Polymerase Chain Reaction/methods , Quebec/epidemiologyABSTRACT
The objectives of this study were to characterize methicillin-resistant Staphylococcus aureus (MRSA) blood culture isolates and to determine their relative importance in both nosocomial and community-acquired infections. A total of 535 MRSA blood culture isolates were analysed. In vitro susceptibility to 14 agents was determined. The genes nuc, mecA and coding for PVL toxin were identified by PCR. All isolates were characterized by PFGE or spa typing to assess their genomic relationships. Most MRSA isolates were retrieved from nosocomial bloodstream infections (474, 89%) and were of the CMRSA2 genotype. Healthcare-associated (HA)-MRSA bloodstream infections were associated with older age (70-89 years, P = 0·002) and most often secondary to central line infections (P = 0·005). Among MRSA strains associated with community-acquired (CA)-MRSA, 28·8% were isolated in intravenous drug users. CA-MRSA genotypes were more frequently found in young adults (20-39 years, P < 0·0001) with skin/soft tissue as the primary sources of infection (P = 0·006). CMRSA10 genotype was the predominant CA-MRSA strain. All MRSA isolates were susceptible to doxycycline, tigecycline, trimethoprim/sulfamethoxazole and vancomycin. Both the presence of the genes coding for PVL toxin (89·8%) and susceptibility to clindamycin (86·5%) were predictive of CA-MRSA genotypes. Whereas in the USA, HA-MRSA have been replaced by USA300 (CMRSA10) clone as the predominant MRSA strain type in positive blood cultures from hospitalized patients, this phenomenon has not been observed in the province of Quebec.
Subject(s)
Bacteremia/microbiology , Methicillin Resistance , Methicillin-Resistant Staphylococcus aureus/drug effects , Methicillin-Resistant Staphylococcus aureus/genetics , Methicillin/pharmacology , Molecular Epidemiology , Staphylococcal Infections/microbiology , Adolescent , Adult , Aged , Aged, 80 and over , Anti-Bacterial Agents/pharmacology , Bacteremia/epidemiology , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Cross Infection/epidemiology , Cross Infection/microbiology , Female , Humans , Male , Microbial Sensitivity Tests , Middle Aged , Quebec/epidemiology , Staphylococcal Infections/epidemiology , Young AdultABSTRACT
Resistance to macrolides among group A streptococci is an increasing problem worldwide. We examined 496 strains phenotypically and genotypically for resistance to erythromycin and clindamycin. Strains were isolated in five different geographical areas representing about 45% of the total Quebec population. The overall resistance rate was 4.6% but varied from 0% in rural areas to 9.4% in Montreal. Of the 23 strains showing resistance to erythromycin, 15 (65%) had an identical pulsed-field gel electrophoresis pattern, were of serotype M28T28 and harboured the erm(TR) gene, suggesting the spread of a single clone. Of the remaining eight strains, two strains had the erm(B) gene, five had the mef gene and one with a different serotype also had the erm(TR) gene.
