In only a few instances has the clonal composition of Staphylococcus aureus collections that include methicillinsusceptible S. aureus (MSSA) been extensively characterized. In order to investigate the clonal composition of MSSA and methicillin-resistant S. aureus (MRSA) and examine whether the infections diagnosed at our hospital were related to internationally distributed S. aureus lineages, we collected 89 clinical S. aureus isolates from patients at a public university hospital in Rio de Janeiro, Brazil, from September 1999 to June 2000. All S. aureus isolates were genotyped by pulsed-field gel electrophoresis and multilocus restriction fragment typing (MLRFT), and a subset (n ؍ 17) was further characterized by multilocus sequence typing (MLST). The 34 MRSA isolates were additionally characterized by SCCmec typing. The MSSA population (n ؍ 55) was grouped into 18 restriction fragment types (RFTs); of these, five RFTs accounted for 67% (37) of the MSSA isolates. MRSA isolates were clustered into only three RFTs (P ؍ 0.02). The majority of MSSA RFTs were related to sequence type 30 (ST30) (12 isolates, 22%), ST1, ST188, and ST432 (6 isolates, 11% each). The predominant MRSA RFT comprised 31 (91%) of 34 isolates; four randomly selected isolates of this RFT were ST239, the previously described widely disseminated Brazilian clone. However, a fifth isolate belonging to this RFT was the ST644, a new single locus variant of ST239. By applying MLRFT and MLST, we found evidence for a clonal structure in MSSA isolates and detected the dissemination of MSSA clonal complexes 1, 5, 8, 30, and 45.
Carbapenem-resistance mechanisms are a challenge in the treatment of
Pseudomonas aeruginosa infections. We investigated changes in
P. aeruginosa carbapenem-resistance determinants over a time
period of eight years after the emergence of São Paulo metallo-β-lactamase in a
university hospital in Rio de Janeiro, Brazil. Patients admitted to the intensive
care unit (ICU) were screened for P. aeruginosa colonisation and
followed for the occurrence of infections from April 2007 to April 2008. The ICU
environment was also sampled. Isolates were typed using random amplified polymorphic
DNA, pulsed-field gel electrophoresis and multilocus sequence typing. Antimicrobial
susceptibility was determined by disk diffusion and E-test, production of
carbapenemases by a modified-CarbaNP test and presence of carbapenemase-encoding
genes by polymerase chain reaction. Non-carbapenemase resistance mechanisms studied
included efflux and AmpC overexpression by PAβN and cloxacillin susceptibility
enhancement, respectively, as well as oprD mutations. From 472
P. aeruginosa clinical isolates (93 patients) and 17 isolates
from the ICU environment, high genotypic diversity and several international clones
were observed; one environment isolate belonged to the blaSPM-1
P. aeruginosa epidemic genotype. Among isolates from infections,
10 (29%) were carbapenem resistant: none produced carbapenemases, three exhibited all
non-carbapenemase mechanisms studied, six presented a combination of two mechanisms,
and one exclusively displayed oprD mutations. Carbapenem-resistant
P. aeruginosa displayed a polyclonal profile after the SPM-1
epidemic genotype declined. This phenomenon is connected with
blaSPM-1 P. aeruginosa replaced by other
carbapenem-resistant pathogens.
Background-Listeriosis occurs mainly in persons at extremes of age and with immunocompromising conditions. It is believed that most cases of listeriosis are acquired in the community. A cluster of listeriosis in hospitalized patients prompted the present investigation.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.