Characterization of oxacillin-susceptible <Emphasis Type="Italic">mecA</Emphasis>-positive <Emphasis Type="Italic">Staphylococcus aureus</Emphasis>: a new type of MRSA

Methicillin-resistant Staphylococcus aureus (MRSA) has been defined as S. aureus having the mecA gene or showing a minimum inhibitory concentration (MIC) of oxacillin higher than 4 mg/l. However, some clinical isolates are mecA-positive and oxacillin-susceptible. Therefore, we surveyed the occurrence of S. aureus having the mecA gene and an MIC of oxacillin of less than 2 mg/l (oxacillin-susceptible MRSA; OS-MRSA) in a total of 480 strains of S. aureus collected from 11 hospitals in different location in Japan isolated from 2003 through 2005. We found 6 strains matching the criteria for OS-MRSA. All 6 strains were staphylococcal cassette chromosome (SCC) mec-positive, without exception, and 4 strains showed the SCCmec type III-variant, which is unique in Japan. These OS-MRSAs were least resistant to oxacillin among the MRSAs tested and they were within the susceptible range to seven other beta-lactam antibiotics tested. Thus, OS-MRSA may become a high-resistant MRSA upon the treatment of patients with beta-lactam antibiotics. To characterize whether these OS-MRSAs were hospital-acquired or community-acquired MRSAs, we tested for the presence of the genes encoding toxins. Genes encoding hemolysin, exfoliative toxin, enterotoxin, toxic shock syndrome toxin-1, and Panton-Valentine leukocidin were found in 6, 4, 0, 0, and 0 strains, respectively. These results revealed that OS-MRSAs could be classified as a new type of MRSA that exhibits properties distinguishable from either hospital- or community-acquired MRSA. Coagulase typing of the OS-MRSAs supported the above conclusion. In this study, the occurrence of OS-MRSA at a certain frequency was noted; precautions are called for in the classification of oxacillin-resistant S. aureus and in the treatment of OS-MRSA infection.     

<Emphasis Type="Italic">Mycobacterium peregrinum</Emphasis>: bactericidal activity of antibiotics alone and in combination

Mycobacterium peregrinum is a rapidly growing mycobacterium that is occasionally associated with disease at different locations. At present, little information is available on antibiotic activity against this microorganism. For this reason, we have carried out a study on the in vitro activity of 15 antibiotics, alone and in combination, against M. peregrinum. Our study shows that the new fluoroquinolones with a C8-methoxy group, especially moxifloxacin, exhibit greater activity against this species. These data should be evaluated in clinical assays or animal models in order to confirm their clinical significance.     

Successful treatment with faropenem and clarithromycin of pulmonary <Emphasis Type="Italic">Mycobacterium abscessus</Emphasis> infection

 Mycobacterium abscessus accounts for 80% of rapidly growing mycobacterial pulmonary infections and can be lethal. Treatment is difficult because of the paucity of effective drugs. We describe a patient with pulmonary M. abscessus infection who was treated with a regimen that included faropenem, a novel oral penem, and clarithromycin. He showed favorable responses to the treatment for more than 12 months. In vitro, faropenem had considerable inhibitory activities against 56 strains of rapidly growing mycobacteria, including M. peregrinum, M. chelonae, M. fortuitum, and M. abscessus (stated in order of increasing minimal inhibitory concentrations). Thus, faropenem has the potential to be used as an adjunctive drug with clarithromycin for the treatment of infection with rapidly growing mycobacteria, including M. abscessus. Received: December 10, 2001 / Accepted: March 18, 2002     

Dissemination of extended-spectrum β-lactamase-producing <Emphasis Type="Italic">Klebsiella pneumoniae</Emphasis> and <Emphasis Type="Italic">Escherichia coli</Emphasis> in Thai hospitals

Fifty clinical isolates of Klebsiella pneumoniae and Escherichia coli with reduced susceptibility to third-generation cephalosporins, collected from 11 hospitals in Thailand, were studied. All isolates were found to produce extended-spectrum β-lactamase (ESBL), as judged by double-disk synergy and combination disk methods. Most ESBL-producing K. pneumoniae isolates were resistant to ceftazidime (94%) and aztreonam (90%). In contrast, most ESBL-producing E. coli isolates were resistant to ceftriaxone (95%) and cefotaxime (74%). Plasmid DNA was isolated and β-lactamase genes were identified by PCR and sequencing. We found that SHV-12 and CTX-M-14 were the main ESBLs responsible for resistance in K. pneumoniae and E. coli, respectively. SHV-27, SHV-28, and CTX-M-14 were detected in three, two, and four K. pneumoniae isolates, respectively. A high genetic diversity among ESBL-producing K. pneumoniae and E. coli isolates was observed. In addition, the finding of a few isolates that produced identical restriction patterns on pulsed field gel electrophoresis (PFGE) suggests the clonal spread of resistant bacteria within the hospital.     

Molecular epidemiology of uropathogenic <Emphasis Type="Italic">Escherichia coli</Emphasis>

Escherichia coli is the most common cause of complicated as well as uncomplicated urinary tract infections (UTIs). Most of these uropathogenic E. coli (UPEC) strains exhibit certain virulence factors (VFs), including adhesins, iron uptake systems, synthesis of cytotoxins, and specific O:K:H serotypes. Molecular epidemiological studies of UPEC have contributed to the discovery of uropathogenic VFs, to an understanding of the pathogenesis of UTIs as ascending infections, and to the clarification of genetic linkages between different virulence genes such as pathogenicity islands (PAIs), which are one of the mechanisms for horizontal VF gene transfers between the same or related species. Uropathogenic VFs not only play an important role individually but also work cooperatively in a fine-tuned manner with coordinated regulation and expression.     

Occurrence of vancomycin-intermediate-resistant <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> in Japan

The Clinical and Laboratory Standards Institute (CLSI) amended the criteria for vancomycin susceptibility and resistance of Staphylococcus aureus in 2006. The earlier criteria had established that S. aureus with minimum inhibitory concentrations (MICs) of vancomycin of < or =4 microg/ml, 8 to 16 microg/ml, and > or =32 microg/ml were vancomycin-susceptible, -intermediate-resistant and -resistant, respectively. The revised recommendation states that bacteria showing vancomycin MICs of < or =2 microg/ml, 4 to 8 microg/ml, and > or =16 microg/ml are -susceptible, -intermediate-resistant, and -resistant, respectively. We examined, based on these new criteria, the vancomycin susceptibility of methicillin-resistant S. aureus (MRSA) strains isolated in Japan from 1978 through 2005 at 17 general hospitals. The results showed that, among 2446 MRSA isolates tested, 8 were classified as intermediate-vancomycin-resistant (VISA). Re-examination of vancomycin susceptibility in these 8 strains in 2006 revealed that 6 strains showed a vancomycin MIC of 4 microg/ml, as tested by the agar dilution method, broth dilution methods, and E-test; the 2 other strains had lost the vancomycin resistance. Pulsed-field gel electrophoresis (PFGE) of the chromosomal DNA of these strains exhibited five unique profiles; 2 strains isolated from the same hospital were identical. These results revealed that at least five different types of VISA strains could be identified in Japan so far according to the new CLSI criteria. All these VISA strains had type II staphylococcal cassette chromosome, mec. This study revealed, for the first time in Japan, the presence of intermediate vancomycin-resistant MRSA in this country.     

First isolation of <Emphasis Type="Italic">bla</Emphasis><Subscript>IMP-7</Subscript> in a <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> in Japan

We report here the first isolation in Japan of a carbapenem-resistant Pseudomonas aeruginosa strain that carries the metallo-β-lactamase gene bla _IMP-7. This isolate revealed high-level resistance to all of the tested antibiotics except for piperacillin, showing a multidrug-resistant phenotype.     

Chronic <Emphasis Type="Italic">Helicobacter pylori</Emphasis> infection is associated with peripheral arterial disease

It is reported that Helicobacter pylori infection is associated with coronary atherosclerosis both epidemiologically and pathogenetically, but no conclusions have yet been reached. Therefore, we investigated the relationship between H. pylori infection and peripheral arterial disease (PAD). Sixty-nine patients with PAD attending Harasanshin General Hospital (Fukuoka, Japan) were compared with 143 controls (age-matched asymptomatic outpatients with hyperlipidemia). H. pylori infection was diagnosed by the detection of IgG antibodies, the (13)C-urea breath test, and histological examination. Multiple logistic regression analysis was used to assess the data. The 69 PAD patients and 143 controls were aged from 50 to 92 years. According to the Fontaine classification, 43/69 PAD patients (62.3%) were grade I, 25 (36.2%) were grade II, and 1 (0.14%) was grade III. The prevalence of H. pylori infection was higher in the PAD patients than in the controls (79.7% versus 44.8%; P < 0.01). Stepwise logistic regression analysis revealed that H. pylori infection and hypertension had a significant influence on the occurrence of PAD. Our results suggest that chronic H. pylori infection may be one of the risk factors for PAD.     

Remarkably high prevalence of <Emphasis Type="Italic">fts I</Emphasis> gene mutations in <Emphasis Type="Italic">Haemophilus influenzae</Emphasis> isolates from upper respiratory tract infections in children of the Sapporo district,Japan

Recently, the frequency of isolation of beta-lactamase-negative ampicillin resistant (BLNAR) strains of Haemophilus influenzae in Japanese children has been increasing rapidly. Drug resistance in BLNAR strains is associated with mutations of the fts I gene, which encodes penicillin-binding protein 3. In the otolaryngological field, only a few reports have been available concerning fts I gene mutations in BLNAR. We investigated the prevalence of fts I gene mutations, by polymerase chain reaction (PCR) genotyping, in H. influenzae isolates from the upper respiratory tracts of children in the Sapporo district, Japan. When the isolates were classified according to PCR genotyping, 34 (44.2%) of 77 isolates were beta-lactamase-negative ampicillin-sensitive (g-BLNAS), 8 (10.4%) were g-low-BLNAR, 30 (39.0%) were g-high-BLNAR, 2 (2.6%) were beta-lactamase-positive ampicillin-resistant (g-BLPAR), and 3 (3.9%) were beta-lactamase-positive ampicillin/clavulanic acid-resistant (g-high-BLPACR). Mutations in the fts I gene were generally parallel to ampicillin susceptibility, and were frequently observed in children who were 7 years or younger. Of the beta-lactams tested, cefditoren showed the strongest inhibition of H. influenzae isolates, and it inhibited g-BLNAR and g-BLPACR. This study revealed a remarkably high prevalence of fts I gene mutations (g-BLNAR and g-BLPACR) in our district. Furthermore, a regional difference in the prevalence of fts I gene mutations was observed even at the district level.     

Fusion of <Emphasis Type="Italic">Gaussia</Emphasis> Luciferase to an Engineered Anti-carcinoembryonic Antigen (CEA) Antibody for <Emphasis Type="Italic">In Vivo</Emphasis> Optical Imaging

The bioluminescent protein Gaussia luciferase (GLuc) was fused to an anti-carcinoembryonic antigen (CEA) antibody fragment, the diabody, for in vivo optical tumor imaging. A 15-amino acid N-terminal truncation (GLΔ15) resulted in a brighter protein. Fusions of the anti-CEA diabody to full-length GLuc and GLΔ15 retained high affinity for the antigen, emitted light, and exhibited excellent enzymatic stability. In vivo optical imaging of tumor-bearing mice demonstrated specific targeting of diabody-GLΔ15 to CEA-positive xenografts, with a tumor/background ratio of 3.8 ± 0.4 at four hours after tail-vein injection, compared to antigen-negative tumors at 1.3 ± 0.1 (p = 0.001). MicroPET imaging using ¹²⁴I-diabody-GLΔ15 demonstrated specific uptake in the CEA-positive tumor (2.6% ID [injected dose]/g) compared to the CEA-negative tumor (0.4% ID/g) at 21 hours. Although further optimization of this fusion protein may be needed to improve in vivo performance, the diabody-GLΔ15 is a promising optical imaging probe for tumor detection in vivo.     

Antibacterial activity and PK/PD of ceftriaxone against penicillin-resistant <Emphasis Type="Italic">Streptococcus pneumoniae</Emphasis> and β-lactamase-negative ampicillin-resistant <Emphasis Type="Italic">Haemophilus influenzae</Emphasis> isolates from patients with community-acquired pneumonia

The suitability of ceftriaxone for penicillin-resistant Streptococcus pneumoniae (PRSP) and ampicillin-resistant Haemophilus influenzae (especially β-lactamase-negative ampicillin-resistant (BLNAR) H. influenzae) and the relationship between in vitro antimicrobial activities and pharmacokinetic parameters were evaluated. The values for percentage of time above the MIC (%T>MIC) for ceftriaxone, cefotiam, flomoxef, sulbactam/cefoperazone, sulbactam/ampicillin, and meropenem, using 400 S. pneumoniae isolates and 430 H. influenzae isolates from patients with community-acquired pneumonia (CAP) from more than 100 geographically diverse medical centers during January to July of 2005, were calculated by measuring the MIC for each isolate and by using patameters of pharmacokinetics. A broth microdilution method was used to determine the MIC, using the guidelines of the Clinical and Laboratory Standards Institute (CLSI). Meropenem showed the lowest MIC against penicillin-susceptible S. pneumoniae, followed by sulbactam/cefoperazone and ceftriaxone. Ceftriaxone had the best activity against penicillin-resistant S. pneumoniae and β-lactamase-negative and β-lactamase–producing ampicillin-resistant H. influenzae. Ceftriaxone was unique, showing a long elimination half-life and low MIC values where its serum level duration time was above the MIC for longer than other cephalosporins. Accordingly, the %T>MIC of ceftriaxone for a once-daily administration greatly exceeded the efficacy levels of those for the other antibacterial agents tested. Ceftriaxone has an excellent balance between in vitro antimicrobial activities and pharmacokinetic profiles; and therefore remains effective as a therapeutic agent against PRSP and BLNAR H. influenzae in CAP.     

Effect of linezolid against postneurosurgical meningitis caused by methicillin-resistant <Emphasis Type="Italic">Staphylococcus epidermidis</Emphasis>: case report

A 67-year-old man who had twice previously undergone operations for a tuberculum sellae meningioma was admitted to hospital for further treatment. After the third surgical intervention, the patient developed persistent low-grade fever and impaired consciousness. Computed tomography, 1 week after surgery, showed postsurgical hydrocephalus. Cerebrospinal fluid (CSF) studies revealed high intracranial pressure (above 30 cm H₂O), and increased cell count (1232/3). One week after the ventricular drainage, coagulase-negative Staphylococcus epidermidis was recovered from his CSF, and antimicrobial susceptibility results indicated that the organism was methicillin-resistant. After 14 days of intravenous vancomycin (VCM) administration failed, linezolid (LZD) was initialized intravenously, resulting in a resolution of the meningitis. After a ventriculoperitoneal shunt procedure was performed, LZD was continued orally, which resulted in a cure. CSF penetration by VCM is reported to be poor, i.e., approximately 10% of serum concentration, which may explain its lack of efficacy. In this case, the penetration of LZD into the CSF was 58.9% of the peak value and 133% of the trough value of serum concentrations. LZD must be considered one of the first-line treatments against surgical-site infection in neurosurgery caused by methicillin-resistant Staphylococci.     

Successfully treated nosocomial <Emphasis Type="Italic">Stenotrophomonas maltophilia</Emphasis> bacteremia following desensitization to trimethoprim-sulfamethoxazole

Stenotrophomonas maltophilia has emerged as an important cause of morbidity and mortality in hospitalized patients. Because trimethoprim-sulfamethoxazole (TMP-SMX) remains the most effective drug for the treatment of S. maltophilia infections, desensitization should be considered in patients with hypersensitivity to TMP-SMX.     

Clinical analysis of pulmonary <Emphasis Type="Italic">Mycobacterium avium</Emphasis> complex disease in association with corticosteroid treatment

We studied the clinical characteristics of nine patients with pulmonary Mycobacterium avium complex disease occurring in association with corticosteroid drugs collected from our associated hospitals during the past 6 years. The average age of the nine patients was 62.2 years and the male/female ratio was 3 : 6. Regarding underlying disease, respiratory diseases existed in four of the patients and nonrespiratory diseases in the other five patients. The duration of corticosteroid treatment ranged from 5 months to 5 years, and the total dose of corticosteroid drugs ranged from 1.78 to 43.20 g. Pulmonary Mycobacterium avium complex disease was detected by clinical symptoms during corticosteroid treatment in six patients, and purified protein derivative was positive in three of eight patients tested. Radiological findings showed an infiltration shadow without cavity and bronchiectasis in the lower lung field. Microbiological examination was smear-positive in three patients, and the isolated mycobacterium was Mycobacterium intracellulare in five patients and Mycobacterium avium in four. Tolerance was shown to all antituberculous drugs, except for clarithromycin, in all patients. Although treatment including clarithromycin was performed for seven patients, the sputum conversion rate was 33% and an improved clinical effect was noted in only one patient. No change occurred in four and worsening occurred in four. Attention should be paid to the clinical symptoms and radiological findings of patients who have received corticosteroid drugs over a long period of time, because pulmonary Mycobacterium avium complex is characterized by atypical radiographic findings with no relationship to the total dose or duration of the administered corticosteroid drugs. Received: August 22, 2002 / Accepted: October 21, 2002     

Splenic abscess in an infant caused by <Emphasis Type="Italic">Streptococcus intermedius</Emphasis>

We report a 20-month-old girl with splenic abscess. The patient was admitted to our hospital because of persistent high fever and abdominal pain. Laboratory data showed leucocytosis and elevated C-reactive protein levels. Abdominal computed tomography showed multiple low-density lesions in the spleen. These findings were consistent with a diagnosis of splenic abscess. She was successfully treated with ultrasonographically guided percutaneous drainage for 11 days and intravenous antibiotic for 17 days. On culture, aspirated fluid from the abscess grew Streptococcus intermedius. This case illustrates that the differential diagnosis of unknown-focus infection in infants should include splenic abscess. We recommend conservative therapy (antibiotics and drainage) as first-line therapy for splenic abscess in pediatric patients, based on the importance of the immunological functions of the spleen.     

A case of cutaneous myiasis due to <Emphasis Type="Italic">Dermatobia hominis</Emphasis> in Japan

We report the 34th imported case of cutaneous myiasis caused by Dermatobia hominis in Japan, which is not a habitat of the fly. A 41-year-old Japanese man noticed an insect-sting-like papule on his left upper back during his stay in Ecuador in March 2004. After his return home, the lesion gradually increased to become a red subcutaneous nodule with a central pore from which serosanguineous fluid drained. Because antimicrobial treatment under a diagnosis of inflammatory atheroma was ineffective, the lesion was incised and a 3rd instar larva of D. hominis was then found and removed. We checked the literature on D. hominis myiasis reported from Japan, and noted the fact, which nobody had previously pointed out, that in Japan only one case of D. hominis myiasis had been diagnosed correctly before a larva was found, and most of the cases were misdiagnosed and inappropriately treated, including 11 cases given unnecessary resection of the nodules. Doctors in Japan should be aware of myiasis so that patients are neither anxious about the disease nor suffer pain, and doctors avoid performing unnecessary resections of the lesions.     

Surgical-site infection with toxin A-nonproducing and toxin B-producing <Emphasis Type="Italic">Clostridium difficile</Emphasis>

To date, few cases of extraintestinal infection with Clostridium difficile have been reported. We describe a case of surgical-site infection with C. difficile following a colonic operation. Administration of metronidazole was considered to be effective for treatment of the infection. The isolate was a toxin A-nonproducing and toxin B-producing strain.     

Primary resistance in <Emphasis Type="Italic">Helicobacter pylori</Emphasis> isolated in children from Iran

Helicobacter pylori-associated infection is extre-mely common in Iran, as in other developing countries, but few data exist on the susceptibility of H. pylori to antimicrobials commonly used in the eradication schedules in this country. This study was performed to determine the resistance rate to six antimicrobial agents used in the treatment of H. pylori infection in dyspeptic Iranian children and to recommend an updated anti-H. pylori treatment regimen to use in children. All H. pylori isolated from children who were undergoing gastroscopy were prospectively collected and subcultured to yield their susceptibility to six antimicrobial agents, by E test and disk diffusion methods. Demographic data and presenting symptoms were also collected. A prospective study was carried out from January 2003 to January 2005 with 100 strains of H. pylori isolated from children (40 girls and 60 boys; age range, 1.5 to 16 years [mean, 9.22 ± 3.25 years]); the strains had been successfully subcultured to yield antimicrobial sensitivity. Overall the H. pylori resistance rate was 95% to metronidazole, 59% to amoxicillin, 16% to clarithromycin, 9% to furazolidone, 7% to ciprofloxacin, and 5% to tetracycline. The most common presenting symptom was abdominal pain. There were no statistically significant differences in antimicrobial resistance rates related to age, sex, or clinical presentation. In the Iranian children, the prevalence of H. pylori resistance was very high to metronidazole and amoxicillin, moderate to clarithromycin, and low to ciprofloxacin and tetracycline.     

Multifocal osteomyelitis due to <Emphasis Type="Italic">Bartonella henselae</Emphasis> in a child without focal pain

We describe a case of an 11-year-old girl who presented with osteomyelitis of the vertebrae and right femur due to Bartonella henselae. Her only symptom was prolonged fever without focal pain. Magnetic resonance imaging (MRI) and nested polymerase chain reaction (PCR) were useful for the diagnosis. Osteomyelitis due to B. henselae should be considered in cases of prolonged fever of unknown origin.     

Prevalence of β-lactamase-nonproducing ampicillin-resistant <Emphasis Type="Italic">Haemophilus influenzae</Emphasis> and <Emphasis Type="Italic">Haemophilus influenzae</Emphasis> type b strains obtained from children with lower respiratory tract infections

The prevalence of strains with ampicillin (ABPC) resistance among Haemophilus influenzae strains isolated from the nasopharynx of children with lower respiratory tract infections has increased significantly during the 6 years from 2000, when it was 41.9%, to 2005, when it reached 60.1%. From 2002, the prevalence exceeded 50%, and the prevalence of β-lactamase-nonproducing ABPC-resistant (BLNAR) strains with a minimum inhibitory concentration (MIC) of ABPC of over 4 μg/ml doubled, from 28.2% in 2002 to 54.7% in 2005. In H. influenzae strains obtained from the nasopharynx of children with lower respiratory tract infections between April 2004 and March 2006, identification of serotype b was defined, using the slide agglutination method. The frequency of isolation of H. influenzae type b (Hib) strains was then measured and the ABPC resistance conditions of the Hib strains were also evaluated. The frequency of the Hib strains was found to be 30 out of 479 strains, 6.3%. Of these 30 strains, BLNAR accounted for 53.3% (16 strains), approximately the same frequency of isolation as that of the BLNAR isolated from all H. influenzae strains during the same period. In Japan, the prevalence of BLNAR strains among clinically isolated H. influenzae strains has continued to increase, and the frequency of isolation of BLNAR strains among Hib strains has also continued to rise. As a countermeasure, attempts at improving resistance have been made through judicious antibiotic use, but concern that the choice of antibiotics for Hib meningitis may become complicated has sparked a keen interest in the introduction of Hib conjugate vaccine. Part of this report was presented at the fifty-fourth general meeting of the Japanese Society of Chemotherapy (Kyoto, May 2006).