Purpose. The decline in methicillin-resistant Staphylococcus aureus (MRSA) isolation rates has become a general observation worldwide, including Japan. We hypothesized that some genetic shift in MRSA might cause this phenomenon, and therefore we investigated the genetic profiles among MRSA clinical isolates obtained from three different epidemic phases in Japan.
Methodology. A total of 353 MRSA isolates were selected from 202 medical facilities in 1990 (pre-epidemic phase), 2004 (epidemic phase) and 2016 (post-epidemic phase). Molecular typing was performed by PCR detection of 22 genes using the polymerase chain reaction (PCR)-based ORF typing (POT) system, including an additional eight genes including small genomic islets and seven toxin genes.
Results. Isolates with a POT1 of score 93, identified as presumed clonal complex (pCC)5-staphylococcal cassette chromosome mec (SCCmec) type II including ST5-SCCmec type II New York/Japan clone, represented the major epidemic MRSA lineage in 1990 and 2004. In 2016, however, a marked decrease in isolates with a POT1 score of 93, along with changes in the epidemiology of toxin genes carried, was noted, where the carriers of tst genes including the tst-sec combination were markedly reduced, and those possessing the seb gene alone were markedly increased. Rather, isolates with a POT1 score of 106, including pCC1 or pCC8 among the isolates with SCCmec type IV, which often links to community-associated MRSA, were predominant. Interestingly, the pCC1 and pCC8 lineages were related to sea and tst-sec carriage, respectively.
Conclusions. Over time, a transition in MRSA genetic profiles from a POT1 score of 93 in 1990 and 2004 to 106 in 2014 was found in Japan.
Purpose. To determine the predominant strains of Bordetella pertussis in Greece during 2010–2015.
Methodology. Infants and children (n=1150) (15 days to 14 years) of Greek, Roma and immigrant origin with different vaccination statuses were hospitalized in Athens, Greece with suspected pertussis infection. IS481/IS1001 real-time PCR confirmed Bordetella spp./B. pertussis infection in 300 samples. A subset of samples (n=153) were analysed by multi-locus variable number tandem repeat analysis (MLVA) and (n=25) by sequence-based typing of the toxin promotor region (ptxP) on DNA extracted from clinical specimens.
Results/Key findings. A complete MLVA profile was determined in 66 out of 153 samples; the B. pertussis MLVA type 27 (n=55) was the dominant genotype and all tested samples (n=25) expressed the ptxP3 genotype. The vaccine coverage in the Greek population was 90 %; however, the study population expressed complete coverage in 2 out of 264 infants (0–11 months) and in 20 out of 36 children (1–14 years). Roma and immigrant minorities represent 7 % of the Greek population, but make up 50 % of the study population, indicating a low vaccine coverage among these groups.
Conclusions. The B. pertussis MT27 and ptxP3 genotype is dominant in Greek, Roma and immigrant infants and children hospitalized in Greece. Thus, the predominant MLVA genotype in Greece is similar to other countries using acellular vaccines.
Purpose. To investigate the distribution of molecular types of methicillin-resistant Staphylococcus aureus (MRSA) in a paediatric intensive care unit (PICU) according to their community-associated (CA) and hospital-associated (HA) source of acquisition, and thus assess the degree to which CA-MRSA has been introduced into the PICU.
Methodology. We implemented an MRSA surveillance in a PICU during 2013–2016 and investigated the genetic diversity of the isolates retrospectively using three genetic typing methods, as well as antibiograms and virulence factor profiles.
Results/Key findings. From 2684 specimens, we identified 60 MRSA isolates, 43 of which were ST59 CA-MRSA. These 43 ST59 MRSA isolates could be further subtyped into 2 clusters and 7 sporadic isolates by pulsed-field gel electrophoresis, and 3 spa types, which demonstrated the genetic diversity in ST59 MRSA. Phenotypic diversity was also demonstrated among these ST59 MRSA isolates, with 12 virulence factor profiles and 4 antibiograms being identified. Epidemiological information showed that 43 ST59 MRSA isolates were both community-associated (15 isolates) and hospital-associated (28 isolates) and caused colonization and various types of infections in different age groups of children.
Conclusions. Our results show that a predominant ST59 CA-MRSA has been introduced into the PICU to a significant extent. This has caused the ST59 HA-MRSA and CA-MRSA in the PICU to be indistinguishable. Our results also demonstrate that when we are interpreting situations where the causative agents of infections focus on very limited pathogenic clones, combined typing methods and epidemiological information are needed to investigate isolates’ genetic and phenotypic diversity to distinguish an outbreak from endemic cases.