Staphylococcus lugdunensis

A dangerous wolf in sheep’s clothing…

uring the last 20 years, when cultured on blood lugdunensis agar. Dhas emerged as an important pathogen implicated in The types of infections caused by S. both community-acquired and lugdunensis, demonstrate the ability nosocomial infections. of this organism to form biofilm (“extracellular slime substance”), First described in 1988, this thus suggesting that this ability seemingly harmless contributes to this organism’s negative staph is increasingly the reputation for virulence. cause of significant invasive infections resembling that of its Jay Hardy, CLS, SM (ASCP) close cousin, S. aureus. Latex Agglutination Tests

Clinical manifestations of infections S. lugdunensis is tube coagulase

with these organisms include: negative, but can often be Jay Hardy is the founder and misidentified since it can produce CEO of Hardy Diagnostics. •Abscesses positive results for clumping factor He began his career in • (bound coagulase), which is used in microbiology as a Medical •Skin and soft-tissue cellulitis rapid slide agglutination tests. Technologist in Santa •Ventriculo-peritoneal shunt Positive results on such kits can be Barbara, California. infection falsely suggestive of S. aureus.

•Spondylodiscitis (infection of the In 1980, he began vertebra and discs) It is recommended that when testing manufacturing culture media •Prosthetic joint infection for S. aureus, an agglutination test for the local hospitals. •Catheter-related bacteremia kit, such as StaphTex, be used Today, Hardy Diagnostics is • which tests for the clumping factor, the third largest media •Osteomyelitis free coagulase, and A to manufacturer in the US. •Endocarditis avoid misidentification.

• associated with To ensure rapid and reliable peritoneal dialysis turn around time, Hardy • Coagulase Tests maintains six distribution

centers, and produces over S. lugdunensis produces a bound 2,700 products used in Pathogenicity coagulase (clumping factor), which clinical and industrial is why the slide coagulase test may microbiology Infections with the tube coagulase- be positive, however it does not throughout the world. negative S. lugdunensis tend to run a produce free coagulase, and, unlike

more severe course, which resemble S. aureus, it will always be tube

that of S. aureus infections rather coagulase negative as in the bottom

than that caused by other coagulase-

negative staphylococci. In addition,

these organisms are frequently

misidentified as S. aureus because

of the similare morphologic

appearance with yellow

pigmentation and complete tube pictured below. oil overlay and can be read out in only two to four hours. Colonies of S. lugdunensis are usually hemolytic, sticky, smooth, Antimicrobial Resistance glossy, yellow, yellow-orange or cream, and about 2-4mm in When first described, S. lugdunensis diameter after 48 hours of was thought to be universally incubation. Hemolysis may be weak susceptible to penicillins and or delayed. Most, but not all, are The slide coagulase must be cephalosporins. However resistance pigmented. They usually have a performed with caution, since S. is increasing and some institutions characteristic odor. aureus, S. lugdunensis, and S. report resistance to penicillin in schleiferi subsp. schleiferi may about half of the isolates. It is Occasionally, the colony size will produce positive results. Due to this important not only to identify S. vary within the same cell strain, ambiguity, it is recommended to use lugdunensis in view of its clinical falsely suggestive of a mixed culture only the tube rather than the slide course, which is more aggressive (see below). coagulase method. than those of commonly isolated coagulase-negative staphylococci, but also to determine its Automated Identification Systems susceptibility to oxacillin by detecting the mecA gene or its Some automated identification product, PBP2’, since resistance has systems are unable to identify S. been reported. S. lugdunensis is lugdunensis due to insufficient usually susceptible to gentamicin, discriminatory biochemical rifampin, vancomycin and reactions (especially lacking in erythromycin. ornithine decarboxylase) or an inadequate database. Microscopic Morphology Habitat

S. lugdunensis is a common human Manual Identification S. lugdunensis is a gram positive cocci that appears in clusters. skin commensal. S. lugdunensis can usually be successfully identified based on a positive test, negative tube Armed with knowledge of this coagulase test, positive PYR test, organism’s characteristics and the and a positive ornithine proper identification tools the decarboxylase test as pictured microbiologist can readily identify below. this dangerous “wolf in sheep’s clothing.”

Jay Hardy, CLS, SM (ASCP) Santa Maria, CA at 1,000X

The Hardy Rapid Ornithine test (cat. no. K279) involves a sterile mineral Scanning electron micrograph