Cocos Gram-positivos

Staphylococcus saprophyticus

Gram-positive cocci in clusters

Identification & Growth

Identification

Catalase-positive, coagulase-negative
Resistant to novobiocin (5 µg disk) — defining feature

Growth Conditions

Blood agar and CLED agar; white to slightly yellowish colonies, 35–37 °C/24 h

Clinical Significance

Cystitis in young, sexually active women, outpatient setting

Intrinsic Resistance

Aztreonam, colistin and nalidixic acid have no activity

Bench Alerts

May be clinically significant even at lower colony counts on urine culture
Routine reporting of fosfomycin and nalidixic acid is not required — follow the standard urinary panel

Clinical Notes

Clinical presentations

Causes acute uncomplicated cystitis and, less commonly, pyelonephritis in young sexually active women.
Symptoms are clinically indistinguishable from urinary infections caused by Enterobacterales, requiring laboratory diagnosis.
Bacteremia is rare and occurs predominantly in the setting of urologic manipulation or complicated urinary infection.

Specimens and collection

Midstream clean-catch urine is the standard specimen; it should be processed within 2 hours or refrigerated.
Lower colony counts than typical for Enterobacterales may still be clinically significant for this organism.
Urine culture should be plated on CLED or MacConkey/blood agar to allow adequate morphologic differentiation.

Epidemiology and at-risk populations

It is the second most common cause of uncomplicated urinary infection in young women, after E. coli only.
Shows seasonality, with incidence peaks in summer in some epidemiologic series.
Rarely affects men, elderly patients, or hospitalized patients, unlike other coagulase-negative staphylococci.

Resistance and therapeutic implications

It is intrinsically resistant to novobiocin, a phenotypic trait historically used to differentiate it from other coagulase-negative staphylococci.
Most isolates remain methicillin/oxacillin-susceptible and susceptible to usual urinary antimicrobials, differing from the hospital S. epidermidis profile.
Therapeutic choice follows the same principles as uncomplicated urinary infection, without need for inducible resistance testing.

Bench and reporting notes

Coagulase-negative, catalase-positive, and novobiocin-resistant (5 µg disk) are the key phenotypic criteria for presumptive identification.
Unlike other CoNS, its isolation in urine culture from a symptomatic patient is generally considered clinically significant even without repeat testing.
MALDI-TOF provides faster and more reliable species identification than conventional biochemical tests.

Sources

Educational decision-support content. It does not replace laboratory validation, current guidelines or review by the responsible professional.

FAQ: Frequently Asked Questions

How to identify Staphylococcus saprophyticus in the lab?

Staphylococcus saprophyticus is identified through catalase-positive, coagulase-negative, resistant to novobiocin (5 µg disk) — defining feature.

What are the intrinsic resistances of Staphylococcus saprophyticus?

This organism is naturally resistant to aztreonam, colistin and nalidixic acid have no activity. These drugs should not be reported as susceptible.

Where is Staphylococcus saprophyticus commonly found?

It is typically associated with cystitis in young, sexually active women, outpatient setting.

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