Definite infective endocarditis: clinical and microbiological features of 155 episodes in one Japanese university hospital.
OBJECTIVE
To evaluate the epidemiology, clinical features, and microbiological features (including antibiotic susceptibility) of infective endocarditis (IE) at Kitasato University Hospital, Japan.


METHODS
We retrospectively analyzed 153 patients (155 episodes) with definite IE according to the Duke criteria, who presented over a 17-year period. The minimum inhibitory concentrations of antibiotics for cultured causative microorganisms were also examined.


RESULTS
Viridans group streptococci were the most common pathogens (36.8%, 57 episodes), followed by Staphylococcus aureus [21.3%, 33 episodes, including 10 episodes due to methicillin-resistant S. aureus (MRSA)]. Thirty-nine of the 40 strains of viridans streptococci were fully susceptible to penicillin. Comparison of IE due to methicillin-sensitive S. aureus (MSSA) and MRSA showed that the latter had a higher mortality rate (34.8%, 8/23 vs. 70.0%, 7/10). Compared with MSSA, IE caused by MRSA was significantly more likely to be related to nosocomial infection (10/10, p < 0.001), hemodialysis (4/10, 40.0%, p = 0.005), and surgery or intravascular catheter insertion (8/10, 80.0%, p = 0.007). There was a significantly higher mortality rate in non-operated (15/43, 34.9%) than in operated (2/21, 9.5%) (p < 0.001) elderly patients. In 92/155 episodes (59.4%), antibiotics were given before blood cultures were obtained. Culture-negative IE occurred in 20.7% (19/92) of patients on antibiotics versus 6.3% (4/63) of those not on antibiotics (p = 0.02). Of 155 episodes of IE, 34 (21.9%) were fatal and staphylococcal had significantly higher mortality than streptococcal IE [(19/40, 47.5%) vs. (7/72, 9.7%); p < 0.001].


CONCLUSIONS
The most frequently isolated pathogens were viridans group streptococci, which differed from other recent studies. In the present study, no penicillin-resistant strains were detected and there was a higher mortality rate for IE caused by MRSA than MSSA. IE should be considered in MRSA patients with the following risk factors: nosocomial infection, hemodialysis, and surgery or intravascular catheter insertion.
Department of Infection Control and Prevention, Kitasato University Hospital, 1-15-1 Kitasato, Sagamihara, Kanagawa, Japan. yoko@med.kitasato-u.ac.jp
Yoko
Y
Takayama
Ryoichi
R
Okamoto
Keisuke
K
Sunakawa
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D003428:Cross Infection / Q000150:complications / Q000382:microbiology; D004696:Endocarditis / Q000453:epidemiology / Q000382:microbiology*; D005260:Female; D006349:Heart Valve Diseases / Q000150:complications / Q000382:microbiology; D006785:Hospitals, University; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D016106:Methicillin Resistance; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects* / Q000302:isolation & purification; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D013203:Staphylococcal Infections / Q000175:diagnosis / Q000188:drug therapy* / Q000453:epidemiology / Q000382:microbiology; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000302:isolation & purification; D013290:Streptococcal Infections / Q000175:diagnosis / Q000188:drug therapy* / Q000453:epidemiology / Q000382:microbiology; D016896:Treatment Outcome; D034363:Viridans Streptococci / Q000187:drug effects* / Q000302:isolation & purification; D055815:Young Adult
D000900:Anti-Bacterial Agents