Molecular and biochemical studies on methicillin-resistant and susceptible Staphylococcus aureus isolates recovered from human and animals

Abstract

We have conducted this study to provide clear insights regarding the prevalence of nasal carriage, and molecular characteristics of S. aureus and methicillin resistant Staphylocossus aureus among healthy individuals, outpatients and health care workers attending health care centers, and local hospitals in Alkanter Alkhyria city, Egypt and Buraydah city, Saudi Arabia. Meanwhile, to give a brief description of the lifestock- associated methicillin resistant S. aureus among 4 different types of animal species in both countries, while data are still scarce and poorly documented in both countries. In total, 613 nasal swabs were randomly collected from human participants including 318 Egyptian, and 295 Saudi Arabian, in addition to 408 animals (203 from Egypt and 205 from Saudi Arabia). S. aureus isolates were characterized by antibiotic susceptibility, presence of mecA and PVL genes, SCCmec typing, spa typing, MLST, and the corresponding MLST CCs. On average basis, S. aureus nasal carriers were defined in 115 Saudi Arabian (38.9%), and 177 Egyptian (55.66%). MRSA was detected in 36.47% of the Egyptian participants, while it was found in 22% of the Saudi Arabian participants. Most MRSA isolates belonged to SCC mec type V and IVa, some remained nontypeable , where 10.7% of MRSA isolates in Saudi Arabia belonged to SCCmec type II. Surprisingly PVL+ isolates were low in frequency among both MRSA and MSSA isolates. Four novel spa types were detected t11648,

t11840, and t11841 in Saudi Arabia and t11839 in Egypt. We found 15 spa types among 64 MRSA isolates from Egypt; the most frequent spa types were t223, t786, t688, and to44, and 20 spa types out of 37 MRSA isolates from Saudi Arabia; the most frequent spa types were t002, t084, and t349 which reveal a high genetic diversity of MRSA in Saudi Arabia. t008, t084, t223, and t267 were coexisted in both countries. Seven clonal complexes (CC5, CC8, CC15, CC22, CC25, CC80 and CC97) were coexisted in both Egypt and Saudi Arabia. The overall MRSA nasal carriage rate was almost equal among animals in both Egypt (29.55%) and Saudi Arabia (31.21%). The prevalence rate of MRSA differs between different animals in both countries, where MRSA prevalence was high in sheep in both countries, meanwhile the prevalence differ between same groups in both countries including cow and goat, where MRSA prevalence was the lowest among buffalo group. Although our collection lacked a representation of isolates from different parts of each country; while we concentrate only on a specific location in each country, but still partially illustrate a picture on MRSA in both countries. In conclusion; a set of control measures is required to prevent further increase in MRSA prevalence, while a substantial proportion of both Healthcare workers, outpatients with or without history of hospital admission are colonized with MRSA isolates according to our results. Further studies are required to follow up the allelic profiles found by this study.

Key Words: S. aureus, CA-MRSA, HA-MRSA, LA-MRSA, nasal carriage, Outpatients , Healthcare workers, healthy individuals, animals, Egypt , Saudi Arabia, PVL gene, SCCmec typing, spa typing, MLST, MLSTCCS, phylogenetic analysis.