Isolation and Characterization of Coagulase-Negative Methicillin-Resistant <i>Staphylococcus aureus</i> from Patients in an Intensive Care Unit

Abstract

Objective: To report the isolation and characterization of four coagulase-negative methicillin-resistant Staphylococcus aureus isolated from patients admitted to the ICU of a Kuwait hospital by bacteriological and molecular methods. Methods: The isolates were characterized by cultural characteristics, Gram stain, catalase, coagulase, DNase and biochemical tests and typed by a combination of antibiogram and pulsed-field gel electrophoresis to evaluate their relatedness. Results: These isolates were gram-positive cocci in clusters, catalase, DNase and slide coagulase-positive but tube coagulase-negative. They gave negative results for ornithine decarboxylase and pyrrolidonyl-arylamidase tests, which indicated that these were not Staphylococcus lugdunensis or Staphylococcus schleiferi, and were identified as S. aureus by API Staph. They had identical antibiograms and pulsed-field gel electrophoresis patterns which suggested that they had a common origin. Conclusion: The results highlight the need to complement the coagulase tests with other tests such as DNase and biochemical tests to correctly identify S. aureus. Coagulase-negative S. aureus appears to be an increasing problem that clinical laboratories should be aware of. They are as virulent as those producing coagulase and can colonize, cause infections and spread among patients.

A coagulase-negative variant ofStaphylococcus aureusfrom bovine mastitis milk

“…The known specificity of all these tests has previously been used to identify atypical variants of Staph. aureus strains isolated from clinical specimens and mastitis milk samples (Kloos & Schleifer, 1975; Heltberg & Bruun, 1984; Smyth et al 1988; Bodén et al 1989; Fox et al 1993; Mackay et al 1993; Laevens et al 1996; Matthews et al 1997; Personne et al 1997; Wilkerson et al 1997; Mlynarczyk et al 1998; Smole et al 1998; Al Obaid et al 1999; van Griethuysen et al 2001; Garbacz et al 2002; Malinowski et al 2009). In fact, Staph.…”

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

“…S. aureus induced illnesses are some of the most globally reported that have the tendencies to lead to death [20][21]. Most strains of S. aureus are capable of producing both types of coagulases, though, occasional strains that produce only the cell-bound coagulase have been reported [22]. Coagulase act on platelets to initiate coagulation of plasma proteins leading to the conversion of fibrinogen to a fibrin clot.…”