ABSTRACT
Staphylococcus intermedius is a zoonotic organism that can be associated with human disease. We report two separate cases of S. intermedius infection in which a false-positive rapid penicillin binding protein 2a latex test in conjunction with the phenotypic properties of beta-hemolysis and coagulase positivity allowed the clinical isolates to masquerade as methicillin-resistant Staphylococcus aureus. 16S rRNA gene sequencing and the absence of mecA revealed the strains to be methicillin-susceptible S. intermedius.
Subject(s)
Diagnostic Errors , Methicillin Resistance , Staphylococcal Infections/diagnosis , Staphylococcus aureus/classification , Staphylococcus/classification , Adult , Bacterial Typing Techniques , Coagulase/metabolism , False Positive Reactions , Female , Hemolysis , Humans , Latex Fixation Tests , Male , Methicillin Resistance/genetics , Microbial Sensitivity Tests , Middle Aged , Penicillin-Binding Proteins/metabolism , Polymerase Chain Reaction , Staphylococcal Infections/microbiology , Staphylococcus/drug effects , Staphylococcus/isolation & purification , Staphylococcus aureus/drug effects , Staphylococcus aureus/isolation & purificationABSTRACT
Helcococci have previously been associated with the colonization of ulcers and infections of the skin and soft tissues. We describe a case of prosthetic joint infection due to a previously undescribed organism that is genetically most closely related to Helcococcus.
Subject(s)
Arthroplasty, Replacement, Knee/adverse effects , Helicobacter/isolation & purification , Aged , Base Sequence , Female , Helicobacter/classification , Helicobacter/genetics , Humans , Molecular Sequence Data , Phylogeny , Postoperative Complications/etiologyABSTRACT
Nocardia veterana is a newly described species named after the veteran's hospital where it was first isolated. This initial type strain was not thought to be clinically significant. We describe three cases of pulmonary disease attributable to N. veterana: two cases in patients presenting with multiple pulmonary nodules in a setting of immunocompromise and one case of exacerbation of chronic pulmonary disease. The isolates were susceptible to ampicillin, imipenem, gentamicin, amikacin, and trimethoprim-sulfamethoxazole and had reduced susceptibilities to ceftriaxone, cefotaxime, minocycline, and ciprofloxacin. The MICs of amoxicillin-clavulanate were higher than that of ampicillin alone, and the bacteria produced a beta-lactamase detectable only after induction with clavulanic acid. Phenotypically, the isolates could not be characterized beyond the Nocardia genus level. All three isolates were definitively identified as N. veterana by PCR and sequencing of the 16S rRNA gene. On the basis of their susceptibility and restriction enzyme analysis profiles, our findings indicate that they could potentially be misidentified as N. nova. These cases illustrate the pathogenic potential of this newly described species and emphasize the importance of accurate identification of Nocardia isolates to the species level by integrated use of phenotypic and genotypic methods.
