Prevalence of Coagulase Negative Strains of Staphylococcus aureus in Clinical Specimens at the University of Benin Teaching Hospital, Benin City, Nigeria

S. O. Onemu

Department of Medical Laboratory Science, Achievers University, Owo, Ondo State, Nigeria.

M. O. Onemu-Metitiri

School of Sciences, Engineering and Environment, University of Salford, United Kingdom.

Emmanuel Ifeanyi Obeagu *

Department of Medical Laboratory Science, Kampala International University, Uganda.

*Author to whom correspondence should be addressed.


The test for coagulase activity is a simple and non-expensive test for the identification of S. aureus strains from clinical samples in resource-poor settings. The results of these tests have been reported to vary with the source of plasma and with some atypical strains that test negative with the coagulase test. The study was carried out to determine if misidentification of strains of S. aureus exists on account of the reliance on the coagulase tests. Clinical isolates of Staphylococci that tested negative by the coagulase tests from wounds, pus, aspirates, blood cultures and urogenital samples were collected and re-tested by the slide and tube coagulase tests and confirmed to be negative. Each isolate was inoculated onto mannitol sat agar and DNAse agar plates and incubated at 37oC for 18 h. Isolates that fermented mannitol and showed a positive DNAse test were 25/366 (6.8%). The highest number of coagulase-negative Staphylococcus aureus (CNSA) occurred within blood culture samples 25.7% and in wound, pus and aspirates, 6.9% and the least proportion, 2.9% from urogenital samples. The generation of CNSA strains is strongly associated with severely-ill patients and the potential for the administration of cell-wall inhibiting antibacterial agents may have important roles to play in the emergence CNSA. The inclusion of DNAse test in the routine identification of staphylococci is advocated especially when an isolate has tested coagulase-negative.

Keywords: S. aureus, coagulase test, atypical strains, misidentification, DNAse

How to Cite

Onemu , S. O., Onemu-Metitiri , M. O., & Obeagu , E. I. (2023). Prevalence of Coagulase Negative Strains of Staphylococcus aureus in Clinical Specimens at the University of Benin Teaching Hospital, Benin City, Nigeria. Asian Journal of Research in Infectious Diseases, 14(4), 49–53.


Kohayashi SD, Malachova N, Deleo FR. Pathogenesis of Staphylococcus aureus abscesses. Am. J. Pathol. 2015;185(6): 1518-1527.

Parlet CP, Brown MM, Horswill. Commensal Staphylococci Influence Staphylococcus aureus skin colonization and disease. Trends Microbiol. 2019;27(2): 497-507.

Chukwueze CM, Okpala OV, Obeagu EI. Prevalence of Methicillin resistant Staphylococcus aureus in patients with surgical wounds attending Esuth, Parklane. Int. J. Adv. Multidiscip. Res. 2022;9(9):1-2.

Onemu SO, Ademulegun F, Onemu-Metitiri MO, Obeagu EI, Hassan AO. The contribution of curable plasmid-mediated resistance in isolates of staphylococcus aureus at the university of benin teaching hospital, Benin City, Nigeria. Asian Journal of Dental and Health Sciences. 2023;3(3): 30-2.

Hanselman BA, Krul SA, Rousseau J, Wesse JS. Coagulase-positive Staphylococci colonization of humans and their house pets. Can. Vet. J. 2009;50(9).

Chukwueze CM, Okpala OV, Obeagu EI. A systematic review on Methicillin resistant Staphylococcus aureus in patients with surgical wounds. Int. J. Adv. Multidiscip. Res. 2022;9(9):25-36.

Okwuanaso CB, Enweani-Nwokelo IB, Obeagu EI. Isolation and identification of microorganisms in individuals associated with refuse disposal sites and collection centres in Awka metropolis, Nigeria. Academic Journal; 2023.

Peetermans M, Verhamme P, Venssche. Coagulase activity by Staphylococcus aureus: A potential target for therapy. Semin. Thromb. Haemost. 2005;41(4):433-444.

Liesenboughs L, Verhamme P, Vanassche T. Staphylococcus aureus, Master manipulator of the human. Hemostic System J. Thromb. Haemost. 2018;16(3): 441-454.

Gordon YC, Cheung CJ, Bae S, Otto M. Pathogenicity and virulence of Staphylococcus aureus, Virulence. 2021; 12(1):547-561.

Ifediora AC, Obeagu EI, Akahara IC, Eguzouwa UP. Prevalence of urinary tract infection in diabetic patients attending Umuahia health care facilities. J Bio Innov. 2016;5(1):68-82.

Onyenweaku FC, Amah HC, Obeagu EI, Nwandikor UU, Onwuasoanya UF. Prevalence of asymptomatic bacteriuria and its antibiotic susceptibility pattern in pregnant women attending private ante natal clinics in Umuahia Metropolitan. Int J Curr Res Biol Med. 2017;2(2):13-23.

Fries BC, Varshney AK. Bacterial Staphylococci enterotoxin 13. Microbiol. Spect. 2013;1(2):10:1128 AI0002-2012.

Ondusko DS, Nolt D. Staphylococcus aureus. Pediatr. Rev. 2018;39(6):287-298.

Idrees M, Savant S, Karodia N, Rahman A. Staphylococcus aureus biofilm morphology and treatment strategies. Int. J. Environm. Res. 2021;18(14):7602

Skor RL, Jensen KS. Community Associated Methicillin-Resistant Staphylococcus aureus as a cause of Hospital-Acquired Infectious. J. Hosp. Infect. 2009;73(4):364 -370

Otter JA, French GL. Community Associated methicillin-resistant Staphylococcus aureus strains as a cause of Healthcare Associated Infections. J. Hosp. Infect. 2011;79(3):189-193.

Zheng X, Feng R, Wang C, Tian S, Lin J, Zeng W, Zhou T, Xu C. Resistant Profiles of and biological characteristics of rifampicin resistant Staphylococcus aureus: Small colony variants. Infect. Drug Resistance. 2021;14:1527-1536.

Chukwueze CM, Udeani TK, Obeagu EI, Ikpenwa JN, Nneka A. prevalence of methicillin resistant staphylococcus aureus infections among hospitalized wound patients from selected tertiary hospitals within enugu metropolis. Journal of Advances in Medical and Pharmaceutical Sciences. 2022;24(3):18-27.

Guo Y, Son G, Sun M, Wang T, Wang Y. Prevalence and therapies of antibiotics resistance in Staphylococcus aureus. Front. Cell Infect. Microbiol. 2022; 10. Available:

Chukwueze CM, Obu JO, Obeagu EI. Isolation and identification of bacteria from surgical wound attention at Enugu State University Teaching Hospital, Enugu. Int. J. Curr. Res. Chem. Pharm. Sci. 2023; 10(8):35-43.

Obaid IA, Udo EE, Jacob LE. Isolation and characterization of coagulase- negative methicillin resistant Staphylococcus aureus from patients in an intensive care unit, Med. Princ. Pract. 1999;8:230-236.

Xiang H, Vang P, Wang L, Xiang H, Wang T, Xue J, Wang D, Ma H. Isovetexin is a direct inhibitor of Staphylococcus aureus coagulase. J. Microbiol. Biotechnol.i. 2021; 31(10):1350–1357.

Thakur P, Nagyar C, Tak V, Sagal K. Mannitol fermenting and Tube Coagulase-Negative Staphylococci isolates: Unravelling the diagnostic dilemma. J. Lab Physician. 2017;9(1):65-66.

Bush K, Bradford PA. B-lactams and B-lactamase Inhibitors: An Overview, Cold Spring Harb. Perspect. Med. 2016; 6(8):A025247.

Pervaiz N, Ahmad F, Yu W, Mackerel AD, Azam SS. Discovery of beta- lactamase CMY-10 inhibitors for combination therapy against multi-drug resistant Enterobacteriaceae. PLoS ONE. 2021; 16(11):e0244967

Edoo Z, Arthur M, Hugonnet. Reversible Inactivation of a peptidoglycan transpeptidase by a β-lactam antibiotic mediated by β-lactam ring reactivation in the enzyme active site, Scientific Reports. 2017;7:9136.

Yavwood JM, McCormick JK, Paustian ML, Kapur V, Schlievert PM. Repression of Staphylococcus accessory gene regulator in serum and In-Viro. J. Bacteriol. 2002; 184(4):1095-1101.