Prevalence and risk factors of methicillin resistance in small colony variant vs. normal colony variant of Staphylococcus aureus and their clinical outcome at tertiary care referral center: A prospective cross-sectional study

Abstract

Background: The ability of Staphylococcus aureus to maintain a clinically very indolent state depends on various lifestyles the bacteria evolved as Small Colony Variants [SCV] phenotype to safeguard themselves causes chronicity of the infection, providing resistance to the host challenge and antibiotics. Aim: A prospective study has been conducted on none-duplicated S. aureus isolates from bloodstream infections were collected from January 2022-December 2022. Methods: We conducted prospective study considering the characteristics morphology, identification etc, antimicrobial resistance patterns of SCVs were also investigated as per standard guidelines. Results: A total of 585 positive blood culture samples were collected with growth of S. aureus. Among which 140 [23.93%] isolates came out to be SCV, remaining 445 [76.06%] were Normal Colony Variants [NCV] of S. aureus. The prevalence of MRSA among 140 SCV came out to be 80 [57.14%] as compared with 445 NCV was 182 [40.89%]. In this study majority with type 2 DM [51.79%], prolonged hospitalization [42.22%], and placement of central line [36.41%]. Most of the MRSA isolates were found among SCV [57.14%], followed by NCV [40.89%]. The mortality rate was 7.69%, in which the majority of the patients belong to NCV, [84.44%] followed by SCV [15.55%]. Conclusion: The SCV phenotype and antibiotic resistance are interlinked; we still need to learn more about the clinical consequences of infection as well as the risk factors for SCV MRSA. These results highlight the importance of SCV infection and support the routine use of clinical laboratory tests that are sensitive for SCV.