Yoko Takayama

Definite Infective Endocarditis: Clinical and Microbiological Features of 155 Episodes in One Japanese University Hospital

BACKGROUND/PURPOSE 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]. CONCLUSION 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.

Investigation of methicillin-resistant Staphylococcus aureus showing reduced vancomycin susceptibility isolated from a patient with infective endocarditis

A patient with infective endocarditis (IE) caused by methicillin-resistant Staphylococcus aureus (MRSA) was treated with vancomycin (VAN). VAN was ineffective, although therapeutic drug monitoring (TDM) indicated that the recommended trough level was maintained. Five MRSA isolates obtained at various times were analyzed to determine the minimum inhibitory concentration (MIC) and were subjected to population analysis, simulation analysis pulsed-field gel electrophoresis (PFGE). MRSA susceptible to VAN was isolated before and during the early stage of treatment, while an MRSA strain showing reduced VAN MIC was isolated during treatment. Simulation analysis indicated that the viable bacterial count only decreased to 10(-3) to 10(-4) cells after 72 h of incubation. The five MRSA strains isolated at various times were identical by PFGE.

Risk Factors for Surgical Site Infection after Laparoscopic Surgery for Colon Cancer

BACKGROUND Surgical site infection (SSI) occurring as a complication after laparoscopic surgery for colon cancer causes patients pain and psychological stress, prolongs the hospital stay, and increases healthcare costs. The present study was designed to clarify the incidence of, and risk factors for, SSI after surgery for colon cancer. METHODS The study group comprised 670 patients (370 male and 300 female; mean age, 67 y) who underwent laparoscopic surgery for colon cancer in our hospital from January 2010 through April 2015. Univariate and multivariable analyses were performed for 13 risk factors potentially related to post-operative SSI, including gender, age, body mass index, diabetes mellitus, American Society of Anesthesiologists (ASA) score, tumor location, pre-operative hemoglobin concentration, pre-operative serum albumin concentration, operation time, bleeding volume, tumor diameter, pathological stage, and type of sutures used for surgical site closure. RESULTS Surgical site infection occurred in 27 (4%) of the 670 patients. There was no surgery-related death. Univariate analysis of risk factors for SSI showed that the incidence of SSI was substantially lower in patients in whom Triclosan-coated PDS Plus(®) sutures were used for surgical site closure (1.8%, seven of 382 patients) than in those in whom Triclosan-uncoated PDS-II(™) sutures were used (6.9%, 20 of 288 patients; p = 0.0017). The incidence of SSI was substantially greater in patients who had diabetes mellitus (9.3%, seven of 75 patients) than in those who did not (3.4%, 20 of 595 patients; p = 0.0154). On multivariable analysis, only the non-use of triclosan-coated PDS Plus sutures was substantially related to SSI, with an odds ratio of 3.322 (p = 0.021) as compared with the use of triclosan-coated PDS Plus sutures. CONCLUSIONS To prevent SSI after laparoscopic surgery for colon cancer, triclosan-coated PDS Plus sutures should be used for abdominal closure.

Modified Hodge test using Mueller–Hinton agar supplemented with cloxacillin improves screening for carbapenemase-producing clinical isolates of Enterobacteriaceae

Increasing numbers of clinical isolates of Enterobacteriaceae that produce carbapenemase are now being detected, with the most common carbapenemase found among Enterobacteriaceae in Japan being IMP-1-type metallo-β-lactamase. Clinical isolates of Enterobacteriaceae harbouring carbapenemases may be resistant to carbapenem antimicrobial agents, despite apparent in vitro susceptibility when tested according to Clinical and Laboratory Standards Institute criteria. We evaluated the prevalence of carbapenemase producers among isolates of Enterobacteriaceae at our hospital and assessed the performance of the modified Hodge test (MHT) for correctly identifying the phenotype. We studied 47 clinical isolates obtained between 2006 and 2010 for which the MIC of imipenem was 2 or 4 μg imipenem ml- 1. Antibacterial susceptibility testing was done for cephalosporins and carbapenems, the MHT was performed with meropenem and detection of the genes encoding IMP-1, VIM-2, KPC-2 and NDM-1-type metallo-β-lactamases was performed by PCR. Twelve isolates showed a positive result in the MHT with meropenem and were classified as carbapenemase producers. Of these 12 isolates, seven carried the gene for IMP-1 type, but not for VIM-2, KPC-2 or NDM-1 types. None of the carbapenemase genes tested were detected in the other five isolates. All five isolates were Enterobacter cloacae showing high resistance to ceftazidime and aztreonam. False-positive results were inhibited when Mueller-Hinton agar supplemented with 200 mg cloxacillin ml- 1 was used for the MHT. Five of 12 MHT-positive isolates were shown to have no carbapenemase genes and these isolates were high AmpC producers. Adding cloxacillin when performing the MHT prevented such false-positive results. The MHT with cloxacillin can overcome most problems related to detection of carbapenemases.

Detection of Streptococcus agalactiae by immunochromatography with group B streptococcus-specific surface immunogenic protein in pregnant women

BACKGROUND Infection with Streptococcus agalactiae (Group B streptococcus: GBS) is a significant cause of morbidity and mortality in neonates. Screening for GBS is mainly done by culture-based methods, but a reliable result may take several days to obtain and culture is difficult to perform at institutions without a laboratory. We evaluated an immunochromatography method for rapid detection of GBS-specific surface immunogenic protein (Sip) using anti-Sip monoclonal antibodies. MATERIALS AND METHODS A total of 377 cervical and vaginal swabs collected during weeks 35-37 of gestation were inoculated into GBS medium F and incubated. Growth of microorganisms and production of red/orange pigment were assessed by observation. Then culture extracts were subjected to immunochromatography and were also inoculated onto chromID Strepto B (STRB) medium, after which isolates were serotyped and characterized by PCR. RESULTS Of the 377 samples, 54 (14.3%) were positive for GBS by immunochromatography after incubation in GBS medium F. On the other hand, GBS was isolated from 58 (15.4%) of the 377 samples by culture with GBS medium F and STRB medium. Ten of the 58 isolates were non-pigmented and 4 of these were not detected by immunochromatography. The sensitivity, specificity, positive predictive value, and negative predictive value of immunochromatography were 93.1% (54/58), 100% (319/319), 100% (54/54), and 98.8% (319/323), respectively. CONCLUSIONS Immunochromatography was comparable to culture on STRB medium for detecting GBS, indicating that this method could be used clinically for GBS screening in pregnant women even at small institutions.

A very rare case of primary meningococcal arthritis in an adult male

We report here a very rare case of primary meningococcal arthritis of the knee joint without clinical features associated with meningococcemia, meningitis, or meningococcal complications. The patient suffered from diabetes mellitus and had experienced two episodes of joint trauma. Intravenous infusion of ampicillin/sulbactam for 18 consecutive days was successful.

Risk factors for perineal wound infection after abdominoperineal resection of advanced lower rectal cancer

Purpose Abdominoperineal resection (APR) of advanced lower rectal cancer carries a high incidence of perineal wound infection. The aim of this study was to retrospectively evaluate risk factors for perineal wound infection after APR. Methods The study group comprised 154 patients who underwent APR for advanced lower rectal cancer in our department from January 1990 through December 2012. The following 15 variables were studied as potential risk factors for perineal wound infection: sex, age, body-mass index, American Society of Anesthesiologists score, diabetes mellitus, preoperative albumin level, preoperative hemoglobin level, neoadjuvant chemoradiotherapy(NCRT), surgical procedure (open surgery vs. laparoscopic surgery), operation time, bleeding volume, intraoperative transfusion, tumor diameter, invasion depth, and histopathological stage. Results Among the 154 patients, 30 (19%) had perineal wound infection. Univariate analysis showed that a hemoglobin level of ≤11 g/dL (p = 0.001) and NCRT (p = 0.001) were significantly related to perineal wound infection. On multivariate analysis including the preoperative albumin level (≤3.5 g/dL) in addition to the above 2 variables, neoadjuvant chemoradiotherapy (NCRT) was the only independent risk factor for perineal wound infection. Perineal wound infection developed in 31% of patients who received NCRT, as compared with 10% of patients who did not receive NCRT. The relative risk of perineal infection in the former group was 4.092 as compared with the latter group (p = 0.0002). Conclusions NCRT is a risk factor for perineal wound infection after APR in patients with advanced lower rectal cancer.