Cocos Gram-positivos

Staphylococcus haemolyticus

Gram-positive cocci in clusters

Identification & Growth

Identification

Catalase-positive, coagulase-negative, novobiocin-susceptible
Species-level identification by MALDI-TOF or automated panel

Growth Conditions

Blood agar: white to greyish colonies with slight hemolysis
35–37 °C, aerobic, 18–48 h

Clinical Significance

Catheters, prosthetic devices, bacteremia in neonatal units and ICU

Intrinsic Resistance

Aztreonam, colistin and nalidixic acid have no activity against Gram-positive organisms

Bench Alerts

The coagulase-negative staphylococcus most often showing reduced glycopeptide susceptibility — confirm by MIC
Methicillin resistance (cefoxitin) is very frequent in the hospital setting

Clinical Notes

Clinical presentations

Catheter-related bacteremia and late-onset neonatal sepsis, usually with a subacute course.
Prosthetic joint, ventricular shunt and other implanted-device infections.
Peritoneal dialysis peritonitis and late-onset surgical-site infection.

Specimens and collection

Two or more blood cultures from separate venipunctures: a single sample cannot separate infection from skin contamination.
Antisepsis with alcoholic chlorhexidine and respecting drying time reduce the main cause of false results.
Send the removed device for culture when implant-associated infection is suspected.

Epidemiology and at-risk populations

It is among the coagulase-negative staphylococci with the highest multidrug-resistance profile in hospitals.
It colonizes the skin of staff and patients, with clonal spread in neonatal ICUs.
Prematurity, long-dwelling central catheters and prior antibiotic therapy are the main risk factors.

Resistance and therapeutic implications

Oxacillin resistance (mecA) is very frequent: in that case report resistance to all beta-lactams, except ceftaroline when tested.
It is the species with the highest frequency of reduced teicoplanin and glycopeptide susceptibility among coagulase-negative staphylococci.
Like all Gram-positive organisms, it is intrinsically resistant to aztreonam, colistin and nalidixic acid.

Bench and reporting notes

Catalase-positive, coagulase-negative, with large and often beta-haemolytic colonies on blood agar.
Use cefoxitin as the surrogate for oxacillin resistance and confirm glycopeptide MIC in device-associated isolates.
Record the number of positive bottles and time to positivity in the report, data that guide clinical interpretation.

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 haemolyticus in the lab?

Staphylococcus haemolyticus is identified through catalase-positive, coagulase-negative, novobiocin-susceptible, species-level identification by maldi-tof or automated panel.

What are the intrinsic resistances of Staphylococcus haemolyticus?

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

Where is Staphylococcus haemolyticus commonly found?

It is typically associated with catheters, prosthetic devices, bacteremia in neonatal units and icu.

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