Emergence and characterisation of community-associated Methicillin-resistant Staphylococcus aureus at a neonatal special care unit

Abstract

Background: Community-associated methicillin-resistant S. aureus (CA-MRSA) is an emerging healthcare problem among pregnantwomenand neonates worldwide. Until recently, the Maternity hospital in Kuwait has been free of MRSA. However, MRSA was isolated from neonates admitted to the neonatal special care unit in October 2011. This study was conducted to determine the genetic relatedness of MRSA isolated from neonates admitted to special care Units of the Maternity hospital in Kuwait Methods: A total of 21 MRSA were isolated from 20 neonates between October and December 2011.They were characterized using antibiogram, pulsed-field gel electrophoresis (PFGE), SCCmec typing and spa typing and screened for the carriage of genes for Panton Valentine leukocidin (PVL) and capsular polysaccharide types 5 and 8 . Results: All isolates were susceptible to vancomycin, teicoplanin, linezolid, tigycycline and mupirocin but were resistant to trimethoprim (13/21), gentamicin and kanamycin (7/21), ciprofloxacin (5/21), erythromycin and clindamycin (2/22), tetracycline (2/22) and fusidic acid (2/22). PFGE identified seven pulsotypes and subtypes with nine isolates belonging to one cluster (type A). Pulsotypes B, D, E, C, F and G consisted of four, three, two and one isolates respectively. Spa typing differentiated the isolates into 11 spa types with five isolates belonging to spa type t3935, followed by spa types t6269 (3 isolates) and t 6892 (3 isolates), t1084 (2 isolates) and t2962 (2 isolates). Spa types t339, t1548, t5801, t1340, t2810 and t4410 occurred in single isolates. Twenty isolates contained SCCmec IV or V genetic elements that are usually associated with community associated MRSA (CA-MRSA) while one isolates contained SCCmec III element characteristic of healthcare-associated MRSA. Seven isolates spanning four pulsotypes and five spa types contained genes for PVL. Fifteen and six isolates carried genes for types 5 and 8 capsular polysaccharide respectively Conclusion: This study highlighted the heterogeneous emergence of CA-MRSA in the neonatal special care unit which warrants the implementation of a rapid screening protocol for mothers and babies to prevent the establishment and further spread of CAMRSA.