Hospital Epidemiology of Methicillin-ResistantStaphylococcus aureusin a Tertiary Care Hospital in Moshi, Tanzania, as Determined by Whole Genome Sequencing
Objective. To determine molecular epidemiology of methicillin-resistantS. aureusin Tanzania using whole genome sequencing.Methods. DNA from 33Staphylococcusspecies was recovered from subcultured archivedStaphylococcusisolates. Whole genome sequencing was performed on Illumina Miseq using paired-end2×250 bp protocol. Raw sequence data were analyzed using online tools.Results. Full susceptibility to vancomycin and chloramphenicol was observed. Thirteen isolates (43.3%) resisted cefoxitin and other antimicrobials tested. Multilocus sequence typing revealed 13 different sequence types among the 30S. aureusisolates, with ST-8 (n= seven, 23%) being the most common. Gene detection inS.aureusstains were as follows:mecA, 10 (33.3%);pvl, 5 (16.7%);tst, 2 (6.7%). The SNP difference among the six Tanzanian ST-8 MRSA isolates ranged from 24 to 196 SNPs and from 16 to 446 SNPs when using the USA300_FPR3757 or the USA500_2395 as a reference, respectively. The mutation rate was1.38×10-11SNPs/site/year or1.4×10-6SNPs/site/year as estimated by USA300_FPR3757 or the USA500_2395, respectively.Conclusion.S. aureusisolates causing infections in hospitalized patients in Moshi are highly diverse and epidemiologically unrelated. Temporal phylogenetic analysis provided better resolution on transmission and introduction of MRSA and it may be important to include this in future routines.