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1.
Lett Appl Microbiol ; 72(6): 767-773, 2021 Jun.
Article in English | MEDLINE | ID: mdl-33629416

ABSTRACT

Therapeutic options for infections caused by Carbapenem-resistant Enterobacterales (CRE) are restricted and include polymyxins-centred schemes. Evaluation of in vitro susceptibility is difficult and time consuming. Agar-based methodologies are an alternative to broth microdilution (BMD) and we aimed to evaluate the accuracy of those methods among Enterobacterales. A total of 137 non-duplicated CRE were subjected to polymyxin B BMD, agar screening test (Mueller Hinton plates containing 3 µg ml-1 of polymyxin B) and agar dilution (antibiotic serially diluted 0·25-64 µg ml-1 ). CRE of 42·3% were resistant to polymyxin B (MICs range: 0·25->64 µg ml-1 ) and 16·8% presented borderline MICs. Sensitivity, specificity, PPV and NPV were 86·2, 98·7, 98 and 90·7% for screening test and 86·2, 97·5, 96·1 and 90·6% for agar dilution. ME was 0·73 and 1·5% for screening and agar dilution respectively; VME was 5·8% for both techniques. In general, agar-based methods had a good performance. As far as we know, this is the first study to propose an agar screening test using polymyxin B instead of colistin.


Subject(s)
Anti-Bacterial Agents/pharmacology , Carbapenem-Resistant Enterobacteriaceae/drug effects , Carbapenem-Resistant Enterobacteriaceae/growth & development , Polymyxin B/pharmacology , Agar/chemistry , Carbapenems , Colistin/pharmacology , Humans , Microbial Sensitivity Tests , Polymyxins
2.
Diagn Microbiol Infect Dis ; 95(3): 114854, 2019 Nov.
Article in English | MEDLINE | ID: mdl-31366440

ABSTRACT

We analyzed sequences of graSR, vraSR, walKR and rpoB genes in hVISA from Brazil. Five isolates showed mutations in at least one gene. rpoB H481N and graS T224I were the most frequent mutations, followed by graR D148Q and walK A468T. Our study reinforces the heterogeneity of genetic patterns among hVISA.


Subject(s)
Staphylococcus aureus/genetics , Vancomycin Resistance/genetics , Anti-Bacterial Agents/pharmacology , Bacterial Proteins/genetics , Humans , Microbial Sensitivity Tests , Mutation , Staphylococcal Infections/microbiology , Staphylococcus aureus/drug effects , Staphylococcus aureus/isolation & purification , Vancomycin/pharmacology
3.
Epidemiol Infect ; 147: e93, 2019 01.
Article in English | MEDLINE | ID: mdl-30869012

ABSTRACT

Use of pneumococcal conjugate vaccines has caused emergence of non-vaccine serotypes. No Brazilian data specifically about serotype 19A are available. We aimed to evaluate the frequency of occurrence, susceptibility profile and molecular epidemiology of serotype 19A before and after vaccine introduction in Brazil. Pneumococcal identification was performed by the conventional method. Strain serotype was determined by multiplex polymerase chain reaction (PCR) and/or Quellung reaction. Resistance was determined by Etest® and PCR was performed to determine the presence of macrolide resistance genes, ermB and/or mefA. Pneumococci were typed by Multilocus Sequence Typing. Thirty-eight serotype 19A Streptococcus pneumoniae were recovered, mostly from invasive diseases. Prevalence of serotype 19A increased following vaccination (from 3.5% before vaccination to 8.1% after, p = 0.04196). Non-susceptibility increased to most antimicrobials after vaccine introduction and was associated with clonal complex (CC)320. MLST showed nine different STs, which were grouped in one main CC: CC320 (63.9%). During the post-vaccination era, the frequency of this serotype increased significantly from 1.2% in 2011 to 18.5% in 2014 (p = 0.00001), with a concomitant decrease in the genetic variability: ST320 consistently predominated after vaccine-introduction (61.1%). Overall, our results showed a post-PCV10 increase in the frequency of serotype 19A. This was accompanied by a selection of CC320 and antimicrobial resistance.


Subject(s)
Pneumococcal Infections/epidemiology , Pneumococcal Vaccines/administration & dosage , Streptococcus pneumoniae/physiology , Adolescent , Adult , Aged , Aged, 80 and over , Brazil/epidemiology , Child , Child, Preschool , Female , Humans , Infant , Infant, Newborn , Male , Microbial Sensitivity Tests , Middle Aged , Multilocus Sequence Typing , Pneumococcal Infections/microbiology , Serogroup , Streptococcus pneumoniae/classification , Vaccination , Young Adult
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