Rothia spp.

Rothia belongs to the family Micrococcaceae – the same family as Micrococcus spp., Stomatococcus spp. and Kocuria spp.

There are 8 species of Rothia – but only Rothia dentocariosa and Rothia mucilaginosa has been associated with human disease.

It is a member of the human mouth and upper respiratory tract flora.

Rothia is an opportunistic pathogen and has been reported to cause –

• Bloodstream infection /bacteraemia

• Skin and soft-tissue infections in children

• CNS infection – meningitis

• Pneumonia

• Necrotizing fasciitis

• Prosthetic joint infection

• Endocarditis and

• Peritonitis

Risk factors for Rothia infection – Immunocompromised state or some form of breach in host defence is associated with Rothia infection. A case series suggested a significant association was seen with steroid use (81% versus 13%; P= 0.0014) and fluoroquinolone use (86% versus 13%; P≤ 0.0001) preceding bacteremia in neutropenic patients. [Abidi, 2016]

Other risk factors are -

• Leukaemia, solid tumour 

• Neutropenia

• Central venous access

• Valvular heart disease

• Continuous ambulatory peritoneal dialysis and

• Intravenous drug abuse (IVDU)

• Dental and head-neck surgery

Rothia Gram-stain

Gram-positive cocci may appear singly, in pair, in clusters or chains – mostly pairs/clusters. However, Microcolonies on agar surface are composed of filamentous branched elements which rapidly fragment into bacillary or coccoid forms, resembling Actinomyces or Nocardia species [PHE SMI].

• It grows in aerobic or microaerophilic conditions but not anaerobically

• it does not grow on MacConkey agar.

• Weakly catalase-positive or catalase variable

• Oxidase-negative

• Colony – on blood agar clear/white, nonhemolytic, mucoid/sticky colonies – adherent to the agar surface. They may have a spooked wheel appearance.

• It is susceptible to bacitracin and hydrolyses aesculin

• Unable to grow in presence of 5% sodium chloride.

• Rothia is uniformly susceptible to vancomycin (glycopeptides).

• It is also sensitive to penicillin, amoxicillin, tetracyclines, rifampicin, 2nd/3rd generation cephalosporins, carbapenems.

• Following drugs tend to have higher MIC – fluoroquinolones, aminoglycosides, co-trimoxazole, erythromycin, clindamycin and fosfomycin.

• There is no specific EUCAST/CLSI standard, but EUCAST non-species specific breakpoints can be used (Ekkelenkamp, Staphylococci and micrococci, Infectious Diseases 3e).

• Glycopeptides are usually used in treatment, but combination therapy (beta-lactam with rifampicin/aminoglycosides) has also been reported.