External quality control survey on identification of microorganisms using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry（ MALDI-TOF MS） is a bacterial typing tool that was approved as a medical device in 2011. However, external accuracy control examination of bacterial typing using mass spectrometry is still only performed on a small scale. In this study, E. faecium and S. maltophilia were selected and tested according to established procedures using Score Values at 228 institutions. The Score Values for MALDI Biotyper were 2.43±0.08 for E. faecium and 2.38±0.08 for S. maltophilia; and those for VITEK MS/PRIME were 99.9±0.0 for E. faecium and S. maltophilia. These results suggest that it is useful to evaluate external accuracy control with Score Values using the procedures we have developed.

A Low Body Mass Index Is Associated with Unsuccessful Treatment in Patients with Mycobacterium avium Complex Pulmonary Disease

Background: A low body mass index (BMI) has been reported to be a poor prognostic factor for Mycobacterium avium complex pulmonary disease (MAC-PD). The purpose of this study was to clarify the clinical features of MAC-PD in cases with a low BMI. Methods: This retrospective study analyzed the data of patients diagnosed with MAC-PD at Saga University Hospital between 2008 and 2019. The analyzed patient characteristics included age, gender, BMI, symptoms, laboratory data, chest computed tomography findings, and the treatment courses. We also investigated the factors associated with successful treatment. Results: In total, 144 patients were included in this study. The low-BMI group (BMI < 18.5 kg/m²) had a higher incidence of sputum, Mycobacterium intracellurare infection, and cavitary lesions, in addition to lower blood lymphocyte counts, higher neutrophil–lymphocyte ratios, and a lower prognostic nutritional index (PNI) when compared to the preserved-BMI group (BMI ≥ 18.5 kg/m²). Sixty-six of the 144 patients (45.8%) received treatment. Hemosputum, acid-fast bacillus sputum smear positivity, low lymphocyte counts, a low PNI, and unsuccessful treatment (48.5% vs. 24.2%, p < 0.05) were found to be associated with a low BMI. Conclusions: A low BMI is associated with cavitary lesions, malnutrition, and unsuccessful treatment in MAC-PD.

Examination of conditions for regular internal quality control in identification of microorganisms using MALDI-TOF MS

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was approved for medical use in 2011, and is currently used as a rapid, accurate and low-cost technique for bacterial identification. Microbiological testing and internal accuracy control in Japan are mainly implemented in accordance with the standards of the Clinical and Laboratory Standards Institute (CLSI). However, few facilities perform internal accuracy control of bacterial identification by MALDI-TOF MS. Therefore, we examined the procedures for internal accuracy control of bacterial identification using MALDI-TOF MS in daily work at clinical laboratories in the seven hospitals.

Community-acquired Disseminated Exophiala dermatitidis Mycosis with Necrotizing Fasciitis in Chronic Graft-versus-host Disease

We herein report a case of systemic phaeohyphomycosis by Exophiala dermatitidis (E. dermatitidis) with chronic graft-versus-host disease (GVHD) after allogeneic hematopoietic stem cell transplantation (HSCT). The patient had been taking oral corticosteroids for years to control the GVHD. Yeast-like fungi were identified in a blood culture, so treatment with micafungin (150 mg/day) was begun, with no improvement. The patient passed away on hospital Day 12. A sequence analysis of rRNA revealed the isolate to be E. dermatitidis. This report brings attention to an emerging mycosis of community-acquired Exophiala species infection in the very-late phase after allogenic HSCT in patients with chronic GVHD.

Clinical utility of direct application of matrix-assisted laser desorption ionization time-of-flight mass spectrometry and rapid disk diffusion test in presumptive antimicrobial therapy for bacteremia

OBJECTIVE

To study how and to what degree the rapid pathogen identification by MALDI-TOF MS coupled with rapid disk diffusion test improve the current clinical practice of patients with bacteremia in a tertiary teaching hospital with full-time ID consultation service.

PATIENTS AND METHODS

MALDI-TOF MS and 8H disk diffusion tests were directly applied to the positive blood cultures samples and the results were reflected on antimicrobial therapy (n = 119). The appropriateness of antimicrobial selection through these interventions was verified with conventional culture results in comparison with historical control (n = 129). The mortality of patients between the two periods was also compared.

RESULTS

The appropriateness of antimicrobial selection was higher (99.2%) in the intervention than in the control group (93.8%) (p 0.024), but there was no difference in 28-day mortality between the two periods (16.8%, 14.8%) (p 0.668). The duration of presumptive antimicrobial therapy with anti-MRSA agents and carbapenem antibiotics did not differ between the two periods indicating that the intervention was not effective in decreasing the unnecessary antibiotics. On the other hand, some bacteremic patients with pathogens whose drug susceptibilities were invariably sensitive to the standard class of antibiotics definitely benefitted from the intervention.

CONCLUSION

The intervention utilizing MALDI-TOF MS and the rapid disk diffusion test may not demonstrate overall improvement in bacteremia mortality in the institution with full-time infectious disease consultants. Its utility has yet to be evaluated in different setting hospitals.

Relationship between the duration of trimethoprim/sulfamethoxazole treatment and the clinical outcome of pulmonary nocardiosis

BACKGROUND

Despite treatment, pulmonary nocardiosis, which is a rare opportunistic disease caused by Nocardia species, has poor clinical outcomes including recurrence and death. Currently, the treatment regimen and duration for pulmonary nocardiosis are not fully understood. The present study aimed to clarify the factors related to the clinical outcome of pulmonary nocardiosis.

METHODS

The medical records of 24 patients with pulmonary nocardiosis were retrospectively reviewed. The patients were divided into two groups based on the outcomes within 2 years: patients with controlled disease (n = 14) and patients who developed recurrence or died (n = 10).

RESULTS

Nocardia was identified by 16S ribosomal RNA sequencing in 17 patients (70.8%) and by conventional biochemical test in five patients (20.8%). The patients' characteristics, clinical findings, radiological features, and treatment history were not different between the two groups. Compared with patients who developed recurrence or died, those with controlled disease had significantly longer total duration of treatment with antibiotics, especially trimethoprim/sulfamethoxazole (67.5 ± 111.6 days vs. 9.0 ± 6.5 days; p = 0.01). Pancytopenia was the most frequent adverse effect of trimethoprim/sulfamethoxazole.

CONCLUSIONS

Longer duration of trimethoprim/sulfamethoxazole treatment was significantly associated with better outcomes of pulmonary nocardiosis. In such cases, antibiotics, especially trimethoprim/sulfamethoxazole, should be administered for more than 3 months.

Staphylococcus saprophyticus native valve endocarditis in a diabetic patient with neurogenic bladder: A case report

A 61-year-old man was admitted to our hospital with 2-day history of malaise and dyspnea. He had mitral prolapse and type II diabetes mellitus with neurogenic bladder, which was cared for by catheterization on his own. On arrival the patient was in septic condition with hypoxemia, and physical examination revealed systolic murmur at the apex. Transthoracic echocardiography revealed vegetation of the mitral and the aortic valve. The presence of continuous bacteremia was confirmed by multiple sets of blood culture, whereby gram-positive cocci was retrieved and identified as Staphylococcus saprophyticus (S. saprophyticus) both phenotypically and genetically. Because two major criteria of the Modified Duke Criteria were met, the patient was diagnosed with native valve endocarditis due to S. saprophyticus. The urine culture was also positive for gram-positive cocci, phenotypically identified as Staphylococcus warneri, which was subsequently identified as S. saprophyticus with the use of 16S rRNA gene sequence analysis and MALDI-TOF MS (matrix-assisted laser desorption ionization time of flight mass spectrometry), indicating strongly that the intermittent catheterization-associated urinary tract infection resulted in bacteremia that eventually lead to infective endocarditis. This patient was treated with vancomycin and clindamycin. Because of multiple cerebral infarctions, the patient underwent mitral and aortic valve replacement on hospital day 5. Blood culture turned negative at 6th hospital day. Antibiotic therapy was continued for six weeks after surgery. The patient's clinical course was uneventful thereafter, and was discharged home. This is the first case report of native valve endocarditis caused by S. saprophyticus of confirmed urinary origin.

Clinical features of enterococcal bacteremia due to ampicillin-susceptible and ampicillin-resistant enterococci: An eight-year retrospective comparison study

Enterococcus consists human bowel flora, but sometimes behave as an important nosocomial pathogen. In order to identify clinical characteristics that help discriminate between ampicillin-susceptible and ampicillin-resistant enterococcal bacteremia in advance for antimicrobial susceptibility testing, a retrospective eight-year study was carried out in patients with enterococcal bacteremia experienced in Saga University Hospital, Japan. A total of 143 patients were included in the analysis: 85 (59.4%) with bacteremia caused by ampicillin-susceptible enterococci and 58 (40.6%) by ampicillin-resistant strains. Hospital-acquired bacteremia was present in 79.0% (113/143) of patients. Abdominal infections, urinary tract infections, and unknown source were predominant foci for the two groups. Patients with ampicillin-resistant enterococcal bacteremia was significantly associated with hematological cancer, immunosuppressive therapy, prior use of antibiotics, and mucositis associated with febrile neutropenia. The 28-day mortality was significantly higher in ampicillin-resistant enterococcal bacteremia. On multivariate analysis, independent risk factors for ampicillin-resistant enterococci were as follows: prior exposures to penicillins and carbapenems, and bacteremia related to mucositis with febrile neutropenia. These findings would assist physicians in deciding whether glycopeptide antibiotics should be included as an empiric antibiotic therapy in patients with suspected enterococcal infections and also those with persistent neutropenic fever refractory to fourth generation cephalosporin. A few cases of MALDI-TOF MS-identified Enterococcus faecium that turned out ampicillin-sensitive were also described to emphasize the importance of taking epidemiological aspects of patients into considerations when deciding initial antimicrobial treatment.

Quantitative Microarray-Based DNA-DNA Hybridization Assay for Measuring Genetic Distances among Bacterial Species and Its Application to the Identification of FamilyEnterobacteriaceae

Quantitative DNA-DNA hybridization to measure the genetic distances among bacterial species is indispensable for taxonomical determination. In the current studies, we developed a method to determine bacterial DNA relatedness on a glass microarray. Reference DNAs representing a total 93 species of Enterobacteriaceae were arrayed on a glass microplate, and signal intensities were measured after 2 hr of hybridization with Cy3-labeled bacterial DNAs. All immobilized DNAs from members of the family Enterobacteriaceae were identified by this method except for DNAs from Yersinia pseudotuberculosis and Y. pestis. These results suggest that quantitative microarray hybridization could be an alternative to conventional DNA-DNA hybridization for measuring chromosome relatedness among bacterial species.

Disseminated Nocardiosis caused by Nocardia concava with acute respiratory failure and central nervous system involvement treated with linezolid

Nocardia concava was identified as a new species in 2005; however, the clinical manifestations of Nocardia concava infection have yet to be clarified. We herein present the case of an immunosuppressed patient who developed disseminated nocardiosis caused by N. concava with multiple abscesses in the lungs, cutis, subcutaneous tissue, skeletal muscles and kidneys accompanied by central nervous system involvement, including meningitis and ventriculitis. The patient was cured with appropriate treatment including linezolid after testing for susceptibility. Linezolid should be considered as an alternative agent for treating disseminated nocardiosis because of its effective distribution to multiple sites.

[Influences of %T>MIC achievement probability due to the difference of the MIC measurement concentration range-analysis of meropenem for Pseudomonas aeruginosa-]

We attempted to analyze any influences to %T>MIC achievement probability due to the difference of the MIC measurement concentration range of MEPM for 613 strains of Pseudomonas aeruginosa by the Monte Carlo simulation method. As for the analysis, we calculated the achievement probability of 30% and 50% for MEPM %T>MIC by the administration volume of MEPM: 250 mg, 500 mg, and 1,000 mg, the administration time: 0.5 h, and 3 h, the administration frequency: 2 times, and 3 times, and the renal excretion capability: Normal, Slight, Moderate, and High abnormal with the 3 types of MIC concentration measurement level 1) <=0.06~>=256 µg/ml: 13 levels, 2) <=0.5~>=32 µg/ml: 7 levels, and 3) <=1~>=16 µg/ml: 5 levels. As the result, we found the following findings; 1. In terms of the administration of normal renal excretion capability, 250 mg, in comparison with 500 mg and 1,000 mg, indicated the differential due to the difference of MIC measurement concentration range. 2. The administration volume of MEPM 500 mg which has been recommended shown the less differential of the achievement probability due to the difference of MIC measurement concentration range. As the renal excretion was shifted through Normal to Slight to Moderate to High abnormal, the differential of the achievement probability due to the difference of MIC measurement concentration range was gradually decreased. With these results, PK/PD analysis is possible for the 5 levels measurement concentration. It is significant that the facility using the automated microbiology analyzer can provide not only the MIC report, but also the information on the appropriate administration method for antibacterial drug by PK/PD analysis.

[Quantitative Bayesian diagnosis developed for lower respiratory tract infections due to methicillin-resistant Staphylococcus aureus]

Using quantitative Bayesian analysis as a clinical epidemiological approach, we developed a diagnosis for lower respiratory tract infection (LRTI) due to Methicillin-resistant Staphylococcus aureus (MRSA). We retrospectively reviewed the charts of 181 subjects--a derivation cohort-with MRSA retrieved from lower respiratory specimens June 2006 to March 2008. Dividing them into infection or colonization (no infection) groups, we compared them for the presence or absence of clinical parameters, including fever > 38 degrees C, MRSA >106 CFU (colony-forming units)/mL, phagocytosis on Gram staining, serum albumin < 3.0 g/dL, and peripheral WBC count > 15,000/mL. We them determined positive and negative likelihood ratios (LR +, LR -) for these parameters to quantify MRSA-LRTI diagnostic probability based on combined likelihood ratios (Bayesian analysis). We then determined Bayesian MRSA-LRTI diagnostic probabilities (BDPs) in 40 subjects with respiratory MRSA--a validation cohort-from May 2008 to October 2008 clinically judged with either infection (n = 14) or colonization (n = 26) by infection control personnel (ICP) blinded to the test (parameter LR+ and LR -). BDPs (mean +/- SD) quantified by combining the four parameters-fever, MRSA CFU, phagocytosis, and serum albumin-were 62.3 +/- 25.4% for 14 judged with infection, and 40.2% +/- 20.4% for 26 patients judged with colonization (p = 0.005). Using a diagnostic probability of 51% as the cut off, we compared positive and negative predictive Bayesian diagnoses ICP judgment, i.c., 77% vs. 85%. The Bayesian approach proved useful in quantitatively diagnosing infectious disease such as MRSA-LRTI that lack established diagnostic, and may aid physicians in deciding the need for specific antimicrobial therapy.

Moraxella catarrhalis bacteraemia associated with prosthetic vascular graft infection

Moraxella catarrhalis, formerly called Branhamella catarrhalis, ‘Neisseria catarrhalis’ or ‘Micrococcus catarrhalis’, is a Gram-negative, aerobic diplococcus frequently found as a colonizer of the upper respiratory tract. Over the last 20–30 years, this bacterium has emerged as a genuine pathogen, and is now considered an important cause of otitis media in children and an aetiological agent in pneumonia in adults with chronic obstructive pulmonary disease. However, bacteraemia due to M. catarrhalis has rarely been reported. Presented here is a case of M. catarrhalis bacteraemia associated with prosthetic vascular graft infection along with a review of the relevant literature.

[Comparison of the antimicrobial susceptibility testing with three automated systems for MRSA, VISA, ESBL-producing Escherichia coli and Klebsiella pneumoniae]

Some automated systems of the identification and susceptibility for microorganisms are used and prevail in hospital laboratories. One of the most serious problems is to perform accurate susceptibility testing for low-level resistant organisms, while antibiotic resistant microbes are increasing in medical fields. To evaluate automated machines for the susceptibility testing, several antibiotic resistant organisms were examined by plural technicians in some laboratories. Each strain of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycinintermediate S. aureus (VISA), extended-spectrum β-lactamase (ESBL) producing Escherichia coli and Klebsiella pneumoniae was tested by three automated systems of WalkAway, VITEK2/VITEK2 compact and Phoenix for susceptibility. The results for antibiotics generated by the systems were compared to those generated by reference methods according to CLSI guidelines. The results of WalkAway, VITEK2/VITEK2 compact, and Phoenix demonstrated 92%, 91%, and 96% of reproducibilities, 92%, 94%, and 91% of MIC agreements, 0.5%, 0.8%, and 0.3% of very major error (VME) and 0.3%, 1.4%, and 2.3% of major error (ME), respectively. All automated systems had a high reproducibility even under the performance of plural technicians, although the differences of VMEs and MEs were observed among the systems. From these data, the automated systems for antimicrobial susceptibility testing were more useful for the detection of antibiotic resistant organisms by understanding the characteristics of each system.

[In vitro susceptibilities to levofloxacin and various antibacterial agents of 12,919 clinical isolates obtained from 72 centers in 2007]

We have reported in this journal in vitro susceptibilities of clinical isolates to antibiotics every year since 1992. In this paper, we report the results of an analysis of in vitro susceptibilities of 12,919 clinical isolates from 72 centers in Japan to selected antibiotics in 2007 compared with the results from previous years. The common respiratory pathogens, Streptococcus pyogenes, Streptococcus pneumoniae, Moraxella catarrhalis and Haemophilus influenzae maintained a high susceptibility to fluoroquinolones (FQs). The resistance of S. pyogenes to macrolides has been increasing every year and this was especially clear this year. Most strains of Enterobacteriaceae except for Escherichia coli showed a high susceptibility to FQs. Almost 30% of E. coli strains were resistant to FQs and the resistance increased further this year. FQs resistance of methicillin-resistant Staphylococcus aureus (MRSA) was approximately 95% with the exception of 45% for sitafloxacin (STFX). FQs resistance of methicillin-susceptible S. aureus (MSSA) was low at about 10%. FQs resistance of methicillin-resistant coagulase negative Staphylococci (MRCNS) was higher than that of methicillin-susceptible coagulase negative Staphylococci (MSCNS), but it was lower than that of MRSA. However, FQs resistance of MSCNS was higher than that of MSSA. FQs resistance of Enterococcus faecalis was 22.5% to 29.6%, while that of Enterococcusfaecium was more than 85% except for STFX (58.3%). In clinical isolates of Pseudomonas aeruginosa derived from urinary tract infections, FQs resistance was 21-27%, which was higher than that of P. aeruginosa from respiratory tract infections at 13-21%, which was the same trend as in past years. Multidrug resistant strains accounted for 5.6% in the urinary tract and 1.8% in the respiratory tract. Acinetobacter spp. showed high susceptibility to FQs. The carbapenem resistant strains, which present a problem at present, accounted for 2.7%. Neisseria gonorrhoeae showed high resistance of 86-88% to FQs. The results of the present survey indicated that although methicillin-resistant Staphylococci, Enterococci, E. coli, P. aeruginosa, and N. gonorrhoeae showed resistance tendencies, and other species maintained high susceptibility rates more than 90% against FQs, which have been used clinically for over 15 years.

[The isolation frequency and antimicrobial susceptibility of Haemophilus influenzae isolated in Saga University Hospital]

Isolation frequency and antimicrobial susceptibility of Haemophilus influenzae isolated in Saga University hospital from October 2002 to September 2003 were investigated. Out of 155 H. influenzae strains subjected 77 were isolated from pediatrics specimens. beta-Lactamase negative ampicillin (ABPC)-resistant H. influenzae (BLNAR), against which MICs of ABPC were higher than 4 microg/mL, were 32 strains (20.6%), and it became 63 strains (41.3%) when Low-BLNAR, against which MICs of ABPC were higher than 2 microg/mL, were included. beta-Lactamase positive ABPC-resistant H. influenzae (BLPAR) were 8 strains (5.2%). Although those BLNAR were also resistant to variety of beta-lactams, fluoroquinolones and other antibiotics were not affected by the level of ABPC-resistance. Resistant strains of BLPAR against SBT/ABPC, a combination of a beta-lactamase inhibitor, were detected but all of them were sensitive to TAZ/PIPC, an another combination. Those strains were able to be considered as beta-lactamase positive amoxicillin-clavulanate resistant H. influenzae (BLPACR). PIPC, TAZ/PIPC, CTRX, CDTR, MEPM, LVFX and CPFX showed good activity among tested antibiotics.

[Antibacterial activity of oral Cephems against various clinically isolated strains]

We determined the antibacterial activities of oral Cephems against isolated from the patients with the respiratory infections, the urinary tract infections, and infections in the obstetrics field of an adult and a child, during the period from 2002 to 2003; Streptococcus pyogenes, Streptococcus pneumoniae, Haemophilus influenzae, Branhamella catarrhalis, Klebsiella pneumoniae and Escherichia coli of 40 strains of each, and Peptostreptococcus spp. 22 strains. S. pneumoniae and H. influenzae strains that resistant is regarded were collected mainly, penicillin-intermediate S. pneumoniae (PISP), penicillin-resistant S. pneumoniae (PRSP) and beta-lactamase negative ampicillin-resistant H. influenzae (BLNAR) strains. The MICs of Cephems except cefaclor (CCL) were < or = 0.03 microgram/mL against all strains of S. pyogenes. The MICs of cefteram (CFTM) and cefditoren (CDTR) were < or = 0.0125 microgram/mL activity against 7 strains penicillin-susceptible S. pneumoniae (PSSP). However the MIC90s of cefditoren (CDTR) was 1 microgram/mL, cefteram (CFTM), and cefcapene (CFPN) were 2 micrograms/mL against PISP and PRSP, were higher than those of other drugs, but showed slightly higher than PSSP. The MIC90s of Cephems. were 0.5-4 micrograms/mL against strains of E. coli. The MIC90s of CFTM was 0.5 microgram/mL, and CDTR, CFPN were 1 microgram/mL against E. coli were higher than those of other drugs. The four strains of E. coli however were highly-resistant which MIC90s of CCL were more than 32 micrograms/mL were obtains. Furthermore it is necessary to pay much attention to the trend of resistant such as E. coli of Cephems. Although all strains showed resistant to AMPC, MIC90 of Cephems were 0.25-1 microgram/mL, good activities against K. pneumoniae. Against beta-lactamase negative ampicillin-susceptible H. influenzae (BLNAS) 23 strains the MIC90s of CCL and other Cephems were 64 micrograms/mL and 0.25-8 micrograms/mL. The MIC90s of CDTR and CFTM were < or = 1 microgram/mL of BLNAR (15 strains). However there of CFDN and CPDX were 8 micrograms/mL and CCL were > or = 16 micrograms/mL. Two strains which were produced beta-lactamase were highly--ABPC resistant. Although B. catarrhalis all strains were produced beta-lactamase and Cephems except for CCL showed better susceptibility than AMPC. The MIC90s of Cephems were 0.25-2 micrograms/mL against Peptostreptococcus spp.

Current practice of management of bacteremic sepsis: a study in a tertiary care teaching hospital in Japan

OBJECTIVE

To investigate how patients with bacteremic sepsis are managed in a tertiary care teaching hospital.

PATIENTS AND METHODS

Prospective observational study on patients with bacteremic sepsis. Clinical and microbiological characteristics of bacteremic sepsis were analyzed in relation to prognosis. Severity of the illness was quantitatively analyzed by the APACHE (Acute Physiology, Age, Chronic Health Evaluation) III scoring system. Also investigated was how closely physicians paid attention to acute physiological alterations in patients.

RESULTS

The 28-day mortalities in fifty hemodynamically stable patients and in twenty-three septic shock patients were 26% and 52%, respectively (p=0.028). Gram-positive organisms accounted for 54% of all organisms, with the mortality and incidence of septic shock being the same as with Gram-negative infections. The mean APACHE III score was 42.9 in survivors, and 76.5 in non-survivors (p < 0.001). Although serum levels of C-reactive protein and acute physiology score (APS) was significantly higher in non-survivors than in survivors, the correlation with APACHE III score was more prominent in APS. The number of vital signs recorded was 1.67 in physicians and 3.6 in nurses (p < 0.001).

CONCLUSIONS

The present study proved that the APACHE III score accurately discriminates between survivors and non-survivors of patients with sepsis. By addressing the need for an objective evaluation of severity of illness, it strongly recommends that physicians should be made aware of physiologically defined sepsis and that they should pay closer attention to patients' physiological alterations to identify the development of sepsis in critically ill patients.

[A trial of infection control measure by clinical microbiology laboratory]

In 1998, we developed a Total Infection Control System in Saga Medical School Hospital, and would like to introduce it for the practical use. This system was named "Dr. FLEMING" (Flexible Microbiological Test & Information System for the New Generation) and is expected to help physicians by providing highly valuable test results and useful information. For example, bacterial identification and drug susceptibility test can be completed within 4-6 hrs after bacterial colony is isolated, and the test report the contains full-colored pictures to enhance understanding. In addition, we have made an information center for infectious disease, where physicians can have access to various data bases outside our hospital. Furthermore, we offer many kinds of useful information to physicians working at other medical facilities to assist their clinical practice of infectious diseases.

Prevalence and genetic diversity of cagD, cagE, and vacA in Helicobacter pylori strains isolated from Japanese patients

BACKGROUND

Although cagD and cagE (cagDE) identified upstream of cagA have been shown to be involved in the induction of interleukin (IL)-8 expression, the relationship between cagDE status and gastroduodenal diseases still remains to be examined. Thus we investigated prevalence and genetic diversity of cagD, cagE, and vacA in Helicobacter pylori strains isolated from patients with peptic ulcer or gastritis.

METHODS

We analyzed 73 H. pylori strains isolated from Japanese patients (gastritis (GA), 15; gastric ulcer (GU), 28; duodenal ulcer (DU), 23; GU and DU, 7). The presence of cagDE was evaluated by polymerase chain reaction (PCR) and Southern hybridization. The vacA genotype was examined by PCR, using type-specific primers.

RESULTS

cagDE was present in 13 (86.7%) of 15 patients with GA, 26 (92.9%) of 28 patients with GU, 21 (91.3%) of 23 patients with DU, and 6 (85.7%) of 7 patients with GU and DU (P = 0.89). vacA signal sequence type s1 was found in 14 (93.3%) of 15 patients with GA, 26 (92.9%) of 28 patients with GU, 22 (95.7%) of 23 patients with DU, and 6 (85.7%) of 7 patients with GU and DU (P = 0.84). Sequences of cagDE and vacA in our Japanese strains were highly homologous with one another, and there were no disease-specific mutations.

CONCLUSIONS

Most of the H. pylori strains in Japan were cagDE-positive, vacA s1 type, regardless of clinical outcome. The present study also indicated that these genes were conserved well among our H. pylori isolates.

Education as a means of reducing medical expenses

In treating patients with infectious diseases, key knowledge and experience are essential in making appropriate clinical decisions. Medical students in Japan receive limited tuition in clinical pharmacology and microbiology in their undergraduate curriculum. Education and guidance in these fields are not always provided, even during postgraduate training. To help overcome this problem, we have devised a quick medical reference system to support antimicrobial chemotherapy, and this has been operating in our hospital since May 1994. This system is integrated in order to convey the maximal significance of test results by providing detailed information on various kinds of pathogens and antibiotics immediately on every computer display. This is a unique system in Japan, and aims to help doctors provide effective therapy. Using this system, we have succeeded in reducing medical expenditure for antimicrobials by around 10%.

Anionic properties of beta-lactam-enhancing factor on methicillin-resistant Staphylococcus aureus

We found a Factor (factor T) in aged mixtures of tungstate and phosphate which greatly enhanced the antibacterial effects of beta-lactams upon methicillin-resistant Staphylococcus aureus (MRSA). Factor T suppressed penicillinase production and the amount of penicillin-binding protein-2' in the membrane fraction, thus sensitizing MRSA strains to beta-lactams. In addition, Factor T caused a metachromatic reaction and prolonged the blood coagulation time, indicating that it is a heparin-like polyanion. Since Factor T becomes ineffective in the presence of a polycation, a charge interaction may play an important role in the enhancing effect. One possibility is that Factor T non-specifically inhibits several anion-sensitive enzymes. Factor T inhibited several nucleotide-interacting enzymes, but not most serum enzymes.

[Clinical bacteriological analysis of Vibrio vulnificus infection--a report of five case]

Clinical features in Vibrio infection are generally represented by gastrointestinal involvements such as food poisoning, and its prognosis is usually good. However, Vibrio vulnificus infection not uncommonly causes serious problems including sepsis, necrotizing fasciitis of the extremities, and other conditions, sometimes resulting in fatal outcome. In the present study, we analyzed clinical microbiological aspects of five cases with V. vulnificus infection. All the strains of V. vulnificus isolated in five patients are oxidase-positive Gram negative rods presenting comma-like configuration, which were yielded on TCBS agar forming green colonies; they were grayish-white in color and viscous in texture on 5% sheep blood agar, identification of bacteria were done using VITEK AMS (BioMérieux). Piperacillin and third-generation cephalosporins were found to have bactericidal activities against these strains. All five cases we experienced have primary ailments, and three cases out of the five had taken perishable sea-food before showing disease symptoms. V. vulnificus has two infection channels; one is external wound and the other is oral intake. The latter is said that it may become serious. This has a rather short period from the starting the symptoms to death, and there is high death rate. For life-saving, it is inevitably necessary to dose an effective antibacterial medicine in the early stage. If we suspect this bacteria in the test laboratory, it is important to report this to the clinical doctor. In other words, this is one of the bacteria that needs prompt treatment and further microbiology testing.

Possible mechanism of action of beta-lactam-enhancing factor on methicillin-resistant Staphylococcus aureus

We have recently found a factor (Factor T) in aged mixtures of tungstate and phosphate which greatly enhances the antibacterial effects of beta-lactams on methicillin-resistant strains of staphylococcal species such as methicillin-resistant Staphylococcus aureus (MRSA), but shows only weak effects on methicillin-susceptible S. aureus and bacterial strains other than staphylococci. Factor T alone did not strongly inhibit cell metabolism and bacterial growth unless an excess amount was added. When Factor T was added to the culture medium beforehand, the growth of MRSA cells was rapidly suppressed just after addition of oxacillin (MPIPC). However, the growth of the cells was inhibited gradually when these two reagents were added in reverse order. For full expression of the enhancing effect, it seemed necessary for cells of MRSA strains to be incubated with Factor T for at least 2-3 hr. When the cells were washed after being sensitized by incubating them for 5 hr with Factor T, it took approximately 1 hr for the cells to recover their resistance to MPIPC. Factor T reduced the amount of penicillin-binding protein-2' (PBP 2'), and thus sensitized the MRSA strains to beta-lactams.

[Isolation of penicillin-resistant Streptococcus pneumoniae in Saga Medical School Hospital]

A recent nationwide increase in beta-lactams-resistant Streptococcus pneumoniae has attracted a great deal of attention. We studied the drug sensitivity of S. pneumoniae isolated from various clinical specimens in Saga Medical School Hospital between April 1988 and December 1991. To determine the drug sensitivity of the strains, we used a micro-dilution method and determined the MIC. Drug resistance was evaluated using MIC of ampicillin (ABPC) as a reference MIC, and the results were roughly classified into the following three groups: sensitive (< or = 0.1 microgram/ml), moderately resistant (0.2-3.13 micrograms/ml) and highly resistant (> or = 6.25 micrograms/ml). The isolation frequency was calculated on the basis of one strain from one patient. No strain of S. pneumoniae with high resistance against ABPC was found in 1988 (94 strains of S. pneumoniae were isolated) and 1990 (115 strains isolated), but one such strain (0.8%) was found among 129 strains isolated in 1989, and 2 such strains (2.4%) among 84 strains isolated in 1991. Moderately resistant strains were isolated at the frequencies of 12.8%, 15.5%, 22.6%, and 21.4% respectively, in 1988, 1989, 1990, and 1991. A sum of the frequencies of "moderately resistant" and "highly resistant" (2.4%) strains was 23.8% in 1991. The frequency of resistant strains is increasing and the intensity of resistance is also being elevated.

Purification and characterization of homospermidine synthase in Acinetobacter tartarogenes ATCC 31105

Homospermidine synthase, catalyzing the formation of homospermidine [H2N(CH2)4NH-(CH2)4NH2] from putrescine and NAD+ with concomitant liberation of NH3, was purified 600-fold over the crude extract with a yield of about 14% to homogeneity from Acinetobacter tartarogenes ATCC 31105. The enzyme had a native molecular mass of 102 kDa, with a pI of 5.0, and was apparently composed of two identical subunits (52 kDa), suggesting that a single protein catalyzes two serial reactions, oxidation of putrescine to 4-aminobutyraldehyde and subsequent reduction of the putative Schiff base formed between this aldehyde and a second molecule of putrescine to homospermidine. The Km values for putrescine and NAD+ were 280 and 18 microM, respectively. 1,3-Diaminopropane and cadaverine were inactive as substrates, and NAD+ could not be replaced by NADP+. 1,3-Diaminopropane and NADH were potent competitive inhibitors. The enzyme had a pH optimum of 8.7, was most active at 30 degrees C, and required K+ and dithiothreitol for full activity. Putrescine and NAD+ protected the enzyme from the inhibition by thiol reagents. The NH2-terminal amino acid sequence was AQWPVYGKISGPVVI. Some of these properties were compared with those of the homospermidine synthases from a photosynthetic bacterium, Rhodopseudomonas viridis and a plant, Lathyrus sativus.

[Hospital infection with methicillin-resistant Staphylococcus aureus (MRSA) in Saga Medical School Hospital, a rapid increase in coagulase type-VIII strains]

Hospital infection with MRSA has increased in Saga Medical School Hospital. The causative MRSA consisted predominantly of coagulase type-II strain before 1989, but after 1990, coagulase type-VII MRSA increased rapidly. This type-VII strain has marked multiple drug-resistance, and the pattern of drug sensitivity of MRSA in this hospital was different from that of MRSA detected in other facilities, which are clinically serious problems, therefore, we conducted an etiological study of the background of the increase in MRSA infection in our hospital. The results of the study are summarized as follows: 1) The proportions of MRSA (on strain from one patient) to all types of S. aureus detected in the hospital were 26% for 1986, 23% for 1988, 37% for 1989, 30% for 1990 and 60% for 1991. The proportion increased greatly in 1991. 2) Coagulase type VII-MRSA was first detected only in 5 patients in 1989, then it tended to spread, and this type (probably derived from the same strain) accounted for 47% of MRSA infection in patients examined in 1991. 3) The study of the drug sensitivity pattern and etiological survey of the infection showed that coagulase type VII-MRSA prevalent in the hospital consisted of two types: CLDM, and EM-sensitive, IPM/CS, and MINO-resistant and TSST-1 non-producing and enterotoxin non-producing type, and CLDM, and EM-sensitive, IPM/CS, and MINO-resistant and TSST-1 non-producing type with enterotoxin serotype A. 4) Coagulase type VII-MRSA (Probably derived from the same strain) was detected in physicians and nurses working in affected wards and also in the patients's room.(ABSTRACT TRUNCATED AT 250 WORDS)

An improved method for the serotyping of free coagulase from Staphylococcus aureus

The serotyping of free coagulase, one of the most reliable ways to identify strains of Staphylococcus aureus, and widely employed in Japan, has been improved by adding magnetite sand to the reaction mixture. Culture medium supernatant and a type-specific antibody are mixed in a well of a microtiter plate, and plasma-enriched bovine fibrinogen is treated with magnetite sand. The use of tranexamic acid and gum arabic in the reaction mixture also increases the sensitivity of the reaction. Finally, the plate is placed on a magnetic stirrer. If the type of the coagulase corresponds to that of the antibody, no clot formation will occur, and this is easily confirmed by the movement of the sand. Although the amount of reaction mixture required is much less than that for the conventional tube method, our new method is able to detect slight increases in viscosity of the reaction mixture due to fibrin formation even before complete clotting occurs, thus providing very high sensitivity. Clot formation can also be judged by observing a turbid mass of fibrin in the well (Hwang's method), but this approach is a little slower than our method involving immobilization of magnetite sand.

Purification and some properties of inducible lysine decarboxylase from Vibrio parahaemolyticus

Inducible lysine decarboxylase from Vibrio parahaemolyticus AQ 3627 was purified to apparent homogeneity and characterized. The enzyme displayed a molecular weight of 531000 by gel filtration and 79000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The enzyme required pyridoxal phosphate as a cofactor, and the pH optimum was 5.5. The Km value for L-lysine was 3.2 mM, and the enzyme was inhibited by 6-aminocaproic acid and alpha-fluoromethyl analogs of cadaverine. delta-Hydroxylysine and S-aminoethyl-L-cysteine was active as substrates to a lesser extent than L-lysine. The amino-terminal amino acid sequence was determined to be Met-Asn-Ile-Phe-Ala-Ile-Leu. These properties were compared with those of other bacterial lysine decarboxylases.

[11 cases of anaphylaxis caused by grand keyhole limpet (abalone like shellfish)]

We reported 11 cases of patients who developed moderate to severe anaphylactic reactions induced by the ingestion of grand keyhole limpet (GKL) and abalone. Specific IgE-mediated hypersensitivity to these shellfish was demonstrated by history, skin prick test, RAST and immunoblotting. The RAST inhibition technique revealed cross antigenicity between GKL, abalone and keyhole limpet hemocyanin. By immunoblotting analysis, the major antigens of GKL are shown in the MW range of about 38 Kd and 80 Kd.

Baddeleyite-Type High-Pressure Phase of TiO2

A high-pressure phase of TiO(2), which had been observed by shock-wave experiments and remained unresolved, has been studied by in situ x-ray diffraction. The single phase was formed at 20 gigapascals and 770 degrees C with the use of sintered-diamond multianvils; it has the same structure as baddeleyite, the stable phase of ZrO(2) at ambient conditions. The coordination number of Ti increases from six to seven across the rutile to baddeleyite transition, and the volume is reduced by approximately 9 percent.

A case of localized Darier's disease

A case of localized Darier's disease was reported. The patient was a 36-year-old Japanese woman, and hyperkeratotic papules in zosteriforme arrangement were persistently noted on the left forehead since the age of 20 years. Histological appearance was same as in classical Darier's disease. Skin atrophy due to long-term application of corticosteroid ointment was observed. Aromatic retinoid ointment was effective in the treatment of the lesions. The literature on localized Darier's disease is reviewed.

Ultrastructure of trichoepithelioma papulosum multiplex

The following features of trichoepithelioma papulosum multiplex (TPM) were revealed by electron microscopy: 1. Proliferation of basaloid cells similar to that in basal cell epithelioma (BCE). 2. Abortive hair shafts and hair papillae. 3. Keratinous cysts surrounded by flat keratinocytes, the cytoplasm of which had small-sized keratohyalin and Odland's bodies. 4. Glycogen deposition near the nuclei, vacuoles filled with amorphous materials and lipid droplets in the cytoplasm of tumor cells. 5. Extracellular compartments, in which fibrous materials, cell fragments, and mucinous substance were found. 6. Melanocytes containing melanosomes in stage II, Langerhans cells involving Birbeck's granules, Merkel cells and other dendritic cells.