DISCUSSION
Rothia mucilaginosa was formerly known as Staphylococcus
salivarius , Micrococcus mucilaginosus , and Stomatococcus
mucilaginosus . Reclassified into a new genus belonging to the familyMicrococcaceae in 2000 based on 16S rRNA
sequencing3. It is an oxidase-negative,
catalase-variable gram-positive coccus bacterium. Gram staining reveals
non-spore-forming, encapsulated gram-positive cocci that can appear in
pairs, tetrads, or irregular clusters. It is facultative anaerobic that
grows well on most nonselective media and in standard blood culture
systems. On sheep blood and chocolate agar, forms clear to gray/white,
nonhemolytic, mucoid or sticky colonies that adhere to the agar
surface4. Usually, it only causes dental plaque and
periodontal disease1. Recently, cases of opportunistic
infections in immunocompromised patients have been reported, including
bacteremia, endocarditis, pneumonia, meningitis , peritonitis and
dermatitis2,5. Remarkably, it has shown prominent
adherence properties, which increase the colonization risk of catheters,
damaged or prosthetic cardiac valves in bacteremic
patients4. The main portal of entry is the oral cavity
after mucosal disruption secondary to chemotherapy-induced mucositis or
mild oral infections6. There are only a few reports onRothia mucilaginosa infections in immunocompromised
children7. Chavan et al reported that those
infections were associated with profound and prolonged neutropenia, use
of CVC and mucositis. 40% had active or relapsed
ALL2. Poyer et al . reported the same with the
addition of steroids use1. In pediatric patients,Rothia mucilaginosa bacteremia has been associated to
complications in up to 45%, including meningitis, pneumonia and
respiratory failure and with a 36% mortality rate in one
serie2. In other report, there were no complications
and one patient died secondary to oncology disease
relapse1. In adults, a mortality rate of 7% has been
described8.
Rothia mucilaginosa is generally susceptible to penicillin,
ampicillin, cefotaxime, imipenem, and vancomycin. It is frequently
resistant to clindamycin, aminoglycosides, sulfamethoxazole/trimethoprim
and ciprofloxacin. However, partial resistance to penicillin has also
been reported in the literature4,9. Therefore,
vancomycin is recommended as empirical therapy7. The
duration of treatment will depend of the diagnosis. Bacteremia alone
with good clinical response is treated for at least ten
days2.
Endocarditis has been reported in 1/29 adults with Rothia
mucilaginosa bacteremia 8 and in prosthetic devices
users4,6. Treatment is valve replacement and
intravenous vancomycin for six weeks4. If valve
replacement is not performed, vancomycin has been associated to
gentamicin or rifampin4. In other Rothia severe
infections like meningitis or septic shock, vancomycin and concomitant
betalactams has been used2.
In our first case, the patient had high risk ALL, prolonged neutropenia
associated with CVC use and three weeks of mucositis. In the context of
endocarditis with persistent fever, antibiotic regimen was changed to
vancomycin plus ceftriaxone. We did not use rifampin or gentamicin
because the patient had a native valve endocarditis. To our knowledge,
this is the first report of Rothia endocarditis in pediatric
patients. In the second case, ALL profound neutropenia and CVC use were
the predisposing factors. There was a rapid clearance of blood cultures
and clinical improvement with the initial treatment. Both patients had
recent use of high steroids dose and the presence of predisposing
factors for Rothia mucilaginosa infection. However, only the
first case presented with prolonged grade III mucositis, which is
crucial in the physiopathology of Rothia bacteremia. This may
influenced the complication with endocarditis.
In summary, although traditionally believed to be an organism of low
virulence, Rothia mucilaginosa is increasingly being recognized
as an emerging opportunistic pathogen in immunocompromised patients.
Predisposing factors has been described. If Rothia mucilaginosais isolated in blood cultures, we recommend the initial use of
vancomycin until susceptibility testing results and the performance of
an echocardiogram, because even if is infrequent, endocarditis is a
severe complication that needs to be ruled out. Pediatricians should be
aware of this organism when treating oncology pediatric patients,
especially with predisposing described factors and in the context of a
gram-positive bacteria bacteremia.