Eriko Kasuga

Bactericidal activities of woven cotton and nonwoven polypropylene fabrics coated with hydroxyapatite-binding silver/titanium dioxide ceramic nanocomposite "Earth-plus".

Background Bacteria from the hospital environment, including linens and curtains, are often responsible for hospital-associated infections. The aim of the present study was to evaluate the bactericidal effects of fabrics coated with the hydroxyapatite-binding silver/titanium dioxide ceramic nanocomposite “Earth-plus”. Methods Bactericidal activities of woven and nonwoven fabrics coated with Earth-plus were investigated by the time-kill curve method using nine bacterial strains, including three Staphylococcus aureus, three Escherichia coli, and three Pseudomonas aeruginosa strains. Results The numbers of viable S. aureus and E. coli cells on both fabrics coated with Earth-plus decreased to below 2 log10 colony-forming units/mL in six hours and reached the detection limit in 18 hours. Viable cell counts of P. aeruginosa on both fabrics coated with Earth-plus could not be detected after 3–6 hours. Viable cells on woven fabrics showed a more rapid decline than those on nonwoven fabrics. Bacterial cell counts of the nine strains on fabrics without Earth-plus failed to decrease even after 18 hours. Conclusion Woven cotton and nonwoven polypropylene fabrics were shown to have excellent antibacterial potential. The woven fabric was more bactericidal than the nonwoven fabric.

An amino acid substitution in PBP-3 in Haemophilus influenzae associate with the invasion to bronchial epithelial cells.

Haemophilus influenzae is a common pathogen of respiratory infections. We examined whether beta-lactamase-negative ampicillin-resistant (BLNAR) strains that are known to have ampicillin resistance due to a substitution of amino acid of penicillin binding protein (PBP)-3, differ from beta-lactamase-negative ampicillin-susceptible strains with regard to invasion of bronchial epithelium. After 3h incubation of each of 34 beta-lactamase-negative ampicillin-susceptible and 57 BLNAR strains in the presence of BEAS-2B cells, a human bronchial epithelium cell line, extracellular bacteria were killed using gentamicin and intracellular bacteria numbered. All nine strains in which the efficiency of invasion was 1% or higher were BLNAR strains. The rate of invasion was significantly greater in strains with PBP-3 amino acid substitution (Met377 to Ile, Ser385 to Thr, Leu389 to Phe, and Asn526 to Lys) (n=34) than in those with no amino acid substitution. Electron microscopy showed that high invasive BLNAR strains were observed in cytoplasm of BEAS-2B cell layer. The injured cells were 9.44+/-1.76% among attaching cells examined by trypan blue staining after 6h. These data may suggest that the amino acid substitution of the PBP in BLNAR strains may at least partly play roles in macropinocytosis, leading to the invasion and injury to epithelial cells.

Characterization of CIA-1, an Ambler Class A Extended-Spectrum β-Lactamase from Chryseobacterium indologenes

ABSTRACT An Ambler class A β-lactamase gene, blaCIA-1, was cloned from the reference strain Chryseobacterium indologenes ATCC 29897 and expressed in Escherichia coli BL21. The blaCIA-1 gene encodes a novel extended-spectrum β-lactamase (ESBL) that shared 68% and 60% identities with the CGA-1 and CME-1 β-lactamases, respectively. blaCIA-1-like genes were detected from clinical isolates. In addition to the metallo-β-lactamase IND of Ambler class B, C. indologenes has a class A ESBL gene, blaCIA-1, located on the chromosome.

Addition of thymidine to culture media for accurate examination of thymidine-dependent small-colony variants of methicillin-resistant Staphylococcus aureus: a pilot study.

Small-colony variants (SCVs) are slow-growing subpopulations of various auxotrophic bacterial strains. Thymidine-dependent SCVs (TD-SCVs) are unable to synthesize thymidine; hence, these variants fail to grow in a medium without thymidine. In this study, we used 10 TD-SCVs of Staphylococcus aureus, of which four strains possessed mecA. We compared the efficacy of a newly modified medium containing thymidine for the detection of TD-SCVs of methicillin-resistant S. aureus (MRSA) to the efficacy of routinely used laboratory media. We observed that none of the 10 TD-SCVs of S. aureus grew in Mueller-Hinton agar, and four TD-SCVs of MRSA failed to grow on all MRSA screening media, except for the ChromID™ MRSA medium. Laboratory tests conducted using medium with thymidine incorporated showed that thymidine did not affect the minimum inhibitory concentrations of oxacillin and cefoxitin for clinical isolates of S. aureus, and was able to detect MRSA, including TD-SCVs. These findings showed that thymidine-incorporated media are able to detect TD-SCVs of MRSA without altering the properties of other clinically isolated MRSA strains.

Ampicillin- and ampicillin/sulbactam-resistant Escherichia coli infection in a neonatal intensive care unit in Japan.

The incidence of ampicillin (ABPC)‐resistant Escherichia coli (E. coli) infection in very low‐birthweight infants has been increasing. The rate of ABPC/sulbactam (ABPC/SBT)‐resistant E. coli in this population, however, is currently unknown. We encountered two cases of severe infection due to resistant E. coli and retrospectively studied the prevalence of ABPC‐ and ABPC/SBT‐resistant E. coli in regular surveillance cultures obtained from all neonatal intensive care unit (NICU) patients between 2000 and 2013. The overall prevalence of ABPC‐resistant E. coli was 39% (47/120), accounting for 63% of cases (32/51) between 2007 and 2013, compared with 22% (15/69) between 2000 and 2006. The prevalence of ABPC/SBT resistance was 17% (20/120), which was similar in both periods (16%, 8/51 vs 17%, 12/69). According to these results, not only ABPC, but also ABPC/SBT‐resistant E. coli must be considered in the NICU.

Isolation of an X-factor-dependent but porphyrin-positive Escherichia coli from urine of a patient with hemorrhagic cystitis

An Escherichia coli isolate was recovered from a 92-year-old female patient with urinary tract infection. Gram-stained preparation of the urine sediment manifested some gram-negative rod-shaped cells, and the urine specimen culture yielded nonhemolytic colonies on sheep blood agar plate. However, no visible colonies appeared on modified Drigalski agar plate. The isolate was finally identified as an X-factor-dependent E. coli. The interesting finding was that the isolate revealed a positive reaction for porphyrin test despite the requirement of hemin. This finding suggested that some pyrrol-ring-containing porphyrin compounds or fluorescent porphyrins had been produced as chemical intermediates in the synthetic pathway from δ-amino-levulinic acid (ALA), although the isolate should be devoid of synthesizing hems from ALA. This was the first clinical isolation of such a strain, indicating that the E. coli isolate should possess incomplete synthetic pathways of hems from ALA.

Characterization of clinically isolated thymidine-dependent small-colony variants of Escherichia coli producing extended-spectrum β-lactamase

Purpose. Thymidine‐dependent small‐colony variants (TD‐SCVs) are difficult to detect or test for antimicrobial susceptibility. We investigated the characteristics of clonal TD‐SCVs of Escherichia coli, both with and without blaCTX‐M‐3, isolated from a patient. Methodology. Mutation in the thyA gene was analysed by sequencing, and morphological abnormalities in the colonies and cells of the isolates were examined. Additionally, conjugational transfer experiments were performed to prove the horizontal transferability of plasmids harbouring resistance genes. Results. The TD‐SCVs contained a single nucleotide substitution in the thyA gene, c.62G>A, corresponding to p.Arg21His. Morphologically, their colonies were more translucent and flattened than those of the wild‐type strain. In addition, cells of the TD‐SCVs were swollen and elongated, sometimes with abnormal and incomplete divisions; a large amount of cell debris was also observed. Changing c.62G>A back to the wild‐type sequence reversed these abnormalities. Conjugational transfer experiments showed that the TD‐SCV of E. coli with blaCTX‐M‐3 failed to transfer blaCTX‐M‐3 to E. coli CSH2. However, the TD‐SCV of E. coli without blaCTX‐M‐3 experimentally received the plasmid encoding blaSHV‐18 from Klebsiella pneumoniae ATCC 700603 and transferred it to E. coli CSH2. Conclusion. Mutation in the thyA gene causes morphological abnormalities in the colonies and cells of E. coli, as well as inducing thymidine auxotrophy. In addition, TD‐SCVs horizontally transmit plasmids encoding resistance genes. It is important to detect TD‐SCVs based on their characteristics because they serve as reservoirs of transferable antibiotic resistance plasmids.

Human intestinal spirochetosis in Japanese patients aged less than 20 years: Histological analysis of colorectal biopsy and surgical specimens obtained from 479 patients

Human intestinal spirochetosis (HIS) is a condition in which spirochetes attach to and colonize the colorectal epithelium. To our knowledge, no comprehensive studies of HIS in young patient have been published in a developed country. This study aimed to determine the incidence and clinicopathological manifestations of HIS in Japanese patients aged less than 20 years. We retrospectively reviewed 3605 biopsy and 92 surgical specimens obtained from 479 patients admitted to Shinshu University Hospital between 1997 and 2014. All slides were reviewed independently by two pathologists to confirm the histological presence of spirochetes. Among 387 patients who underwent biopsy, the most common pathologic diagnosis was ulcerative colitis (12.6%, n = 49). Additionally, about half of the biopsy specimens showed non‐specific, mildly inflamed mucosa (50.6%, n = 196); only one of these cases was HIS. On the other hand, among the surgical specimens, we found no cases of HIS. We concluded that the incidence of HIS in Japanese young patients was 0.2% (1/479 cases). The incidence of HIS in Japanese young patients was very low, and one HIS case was associated with colitis with abdominal pain.

A case of liver abscess co-infected with Desulfovibrio desulfuricans and Escherichia coli and review of the literature

A 73-year-old woman was admitted with consciousness disturbance following a fever. Abdominal computed tomography revealed a large liver abscess with which the presence of Desulfovibrio desulfuricans and Escherichia coli was confirmed by thorough blood and abscess content culture. Empiric meropenem treatment was switched to cefoperazone/sulbactam, followed by ampicillin/sulbactam based on susceptibility testing. Desulfovibrio desulfuricans is a common bacterium that rarely causes liver abscess and may be overlooked during co-infection due to overgrowth of the accompanying bacteria. Clinicians should bear Desulfovibrio desulfuricans in mind and select the appropriate antibiotics according to susceptibility testing when anaerobic bacteria are detected in a liver abscess.

Catheter-Related Bacteremia Due to Gordonia sputi in a Patient with Acute Lymphocytic Leukemia: a Case Report.

Accepted January 4, 2016. J-STAGE Advance Publication February 19, 2016. DOI: 10.7883/yoken.JJID.2015.487 *Corresponding author: Mailing address: Department of Laboratory Medicine, Shinshu University Hospital, 3-1-1 Asahi, Matsumoto 390-8621, Japan. Tel: +81-263-373493, Fax: +81-263-34-5316, E-mail: ggatcc@shinshu-u. ac.jp **Present address: Department of Laboratory Sciences, Gunma University Graduate School of Health Sciences, 3-39-22 Showa-Machi, Maebashi, Gunma 371-8514, Japan. Tel: +81-27-220-8940, E-mail: tmatumoto@ gunma-u.ac.jp Jpn. J. Infect. Dis., 69, 342–343, 2016