SXT Testing: Principle, Procedure, and Results
SXT (trimethoprim-sulfamethoxazole) susceptibility helps presumptively group beta-hemolytic streptococci. Learn the principle, procedure, and how to read SXT with bacitracin to sep...
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Susceptibility-based ID
These are susceptibility based identification test such as optochin sensitivity, bacitracin sensitivity etc.
Furazolidone Susceptibility Test: The Nitrofuran Disk That Confirms Staphylococcus Over Micrococcus
Staphylococci are killed by furazolidone; micrococci grow right up to the disk. This nitrofuran, activated inside the bacterial cell to damage DNA, gives a clean genus-level separa...
Novobiocin Susceptibility Test: How One Disk Tells S. saprophyticus From a Contaminant
A 5 µg novobiocin disk separates S. saprophyticus, a real cause of UTI in young women, from S. epidermidis, usually just skin contamination. Full procedure, the corrected 16mm brea...
Bacitracin Test: Principle, Procedure, Results
Bacitracin susceptibility test principle, procedure, and zone interpretation for presumptive identification of Streptococcus pyogenes (Group A Strep)
Optochin Sensitivity Test: Principle, Procedure, Results
Optochin test principle, procedure, and the 14mm zone cutoff used with bile solubility to confirm Streptococcus pneumoniae