Cecal Tumorigenesis in Aryl Hydrocarbon Receptor-Deficient Mice Depends on Cecum-Specific Mitogen-Activated Protein Kinase Pathway Activation and Inflammation

The aryl hydrocarbon receptor (AhR) is a transcription factor known as a dioxin receptor. Recently, Ahr^-/- mice were revealed to develop cecal tumors with inflammation and Wnt/β-catenin pathway activation. However, whether β-catenin degradation is AhR dependent remains unclear. To determine whether other signaling pathways function in Ahr^-/- cecal tumorigenesis, we investigated histologic characteristics of the tumors and cytokine/chemokine production in tumors and Ahr^-/- peritoneal macrophages. AhR expression was also assessed in human colorectal carcinomas. Of the 28 Ahr^-/- mice, 10 developed cecal lesions by 50 weeks of age, an incidence significantly lower than previously reported. Cecal lesions of Ahr^-/- mice developed from serrated hyperplasia to adenoma/dysplasia-like neoplasia with enhanced proliferation. Macrophage and neutrophil infiltration into the lesions was also observed early in serrated hyperplasia, although adjacent mucosa was devoid of inflammation. Il1b, Il6, Ccl2, and Cxcl5 were up-regulated at lesion sites, whereas only IL-6 production increased in Ahr^-/- peritoneal macrophages after lipopolysaccharide + ATP stimulation. Neither Myc (alias c-myc) up-regulation nor β-catenin nuclear translocation was observed, unlike previously reported. Interestingly, enhanced phosphorylation of extracellular signal-regulated kinase, Src, and epidermal growth factor receptor and Amphiregulin up-regulation at Ahr^-/- lesion sites were detected. In human serrated lesions, however, AhR expression in epithelial cells was up-regulated despite morphologic similarity to Ahr^-/- cecal lesions. Our results suggest novel mechanisms underlying Ahr^-/- cecal tumorigenesis, depending primarily on cecum-specific mitogen-activated protein kinase pathway activation and inflammation.

A case of cervical subcutaneous abscess due to Bordetella hinzii

We present a case of subcutaneous infection caused by Bordetella hinzii in a healthy male. The isolate was successfully identified by gyrB gene sequencing. B. hinzii cannot be distinctively identified using 16S rRNA gene sequencing or by biochemical methods. The number of cases infected with B. hinzii might be underestimated owing to the difficulty in accurate identification, which can be achieved by gyrB gene sequencing to gain knowledge about the species.

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.

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.

Candida concentrations determined following concentrated oral rinse culture reflect clinical oral signs

BACKGROUND

Oral candidiasis is an infection caused by a yeast-like fungus called Candida. Various methods can be used to isolate Candida from the oral cavity. However, it is difficult to correctly and satisfactorily diagnose oral candidiasis because currently no microbiological or laboratory standards based on samples from the oral cavity are available. The aim of this study is to establish a reliable laboratory test for diagnosing oral candidiasis.

METHODS

Oral swab, rinse and concentrated rinse samples were obtained from 200 consecutive outpatients (103 male patients and 97 female patients; mean age, 47.2 years; age range, 9-89 years). Candida colonies from cultured samples were enumerated to compare the sensitivities and specificities of the above sampling methods, and the associations between Candida detection or concentration and the clinical oral signs were examined.

RESULTS

The mean colony numbers were 263 ± 590 CFU/swab for the swab method, 2894 ± 6705 CFU/100 μL for the rinse method, and 9245 ± 19,030 CFU/100 μL for the concentrated rinse method. The median numbers were 23 CFU/swab for the swab method, 56 CFU/100 μL for the rinse method, and 485 CFU/100 μL for the concentrated rinse method. Candida was detected in the oral cavity of 33.5 % and 52.0 % of the outpatients by the swab method and concentrated rinse, respectively. Candida concentrations determined by the concentrated rinse were closely related to the severity of the clinical oral signs. The positive predictive values of residual root, redness of the oral mucosa, denture, glossalgia, dry mouth, and taste disorder were useful predictors of oral candidiasis.

CONCLUSIONS

Concentrated rinse sampling is suitable for evaluating oral candidiasis, and Candida concentrations examined using this method strongly associated with the oral signs associated with Candida infection.

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.

Isolation and molecular characterization of catalase-negative Staphylococcus aureus from sputum of a patient with aspiration pneumonia

Staphylococcus aureus produces various virulence factors. The catalase enzyme, in particular, is considered to be involved in oxidative stress resistance, and catalase activity is an important criterion for differentiating staphylococci from streptococci. In this report, we describe the catalase-negative S. aureus strain SH3064, which was isolated from the sputum of a patient with aspiration pneumonia. To evaluate the causes of the lack of catalase activity in S. aureus SH3064, we analyzed the sequence of katA gene encoding the catalase enzyme in this strain. We amplified the complete sequence of katA gene of S. aureus SH3064 by polymerase chain reaction using 2 sets of primers. The katA sequence showed 99.6% sequence identity (1512/1518 bp) with that of S. aureus ATCC 12600. We detected 2 mutations in the katA gene from S. aureus SH3064, an A217T substitution leading to a threonine 73-to-serine substitution and a single-base pair deletion (c.637delG) resulting in a frameshift mutation. The lack of catalase activity in this strain was attributed to the shift of the nucleotide reading frame.

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.

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.

[Successful isolation of IMP-1 carbapenemase-producing, but not carbapenem-resistant species in Enterobacteriaceae family]

Carbapenemases including Klebsiella pneumoniae carbapenemases (KPC) are widespread among clinical isolates in the family Enterobacteriaceae. In 2008, we isolated 4 IMP-1 metallo-beta-lactamase (MBL) producers of this family having transferable carbapenem-resistance markers. When examined with MicroScan Neg-Combo Panels, all 4 showed imipenem-MIC of either <1 microg/mL or 2 microg/mL, although they were highly resistant to ceftazidime (MIC: >16 microg/mL). When isolates were examined by Sensi-Disc, however, discrepancies were seen in susceptibility testing results against carbapenems, i.e., some strains were susceptible to imipenem but resistant to meropenem. MBL productivity of isolates could be ensured by both sodium mercaptoacetic acid (SMA) and modified Hodge testing. Noted that atypical carbapenemase-producers may be overlooked in routine clinical microbiology laboratory testing, and both SMA disks and modified Hodge tests proved appropriate for accurately detecting such carbapenemase-producers.

[Clinical assessment of novel ChromID ESBL agar plates for detection of ESBL producers in the family Enterobacteriaceae]

Extended-Spectrum beta-Lactamase (ESBL)-producers in the family Enterobacteriaceae are recognized worldwide as nosocomial pathogens, however it is difficult to screen them in the routine laboratory processing. ChromID ESBL agar newly developed for screening ESBL-producing Enterobacteriaceae was released in Japan in April, 2007. We evaluated the clinical assessment of ChromID ESBL agar in routine microbiology laboratory. The 47 strains investigated were clinical isolates belonging to the family Enterobacteriaceae with the MICs of cefpodoxime greater than 2 mug/ml. The 27 ESBL-producers examined were comprising of 19 Escherichia coli, 3 Klebsiella oxytoca, 1 Citrobacter freundii, 3 Enterobacter cloacae, and 1 S. marcescens (ESBL group) and 20 ESBL non-producers consiating of 5 K. oxytoca, 1 Proteus mirabilis, 1 P. vlugaris, 2 Serratia marcescens, 8 C. freundii, 2 Enterobacter cloacae, and 1 E. aerogenes (non-ESBL group). Characterization of beta-lactamase genes was carried out by use of polymerase chain reaction. As the results, the sensitivity and the specificity of ChromID ESBL agar plates after incubation for 18 hours was 100% and 20%, respectively. It should be noted that the values of specificity was extremely low compared with those of the sensitivity. These findings clearly suggested that in cases of utilizing ChromID ESBL agar plates, it should be important to consider its characteristic properties, as even the ESBL-non-producers could grow on these media only when they were resistant to CPDX.

First case of bacteremia due to chromosome-encoded CfxA3-beta-lactamase-producing Capnocytophaga sputigena in a pediatric patient with acute erythroblastic leukemia

Bacteremia due to Capnocytophaga sputigena occurred in a 4-year and 9-month-old Japanese girl patient with acute erythroblastic leukemia in Shinshu University Hospital, Japan. On her admission to the hospital, she had a temperature of 38.2 degrees C with canker sore. Prior to the commencement of chemotherapy, peripheral blood culture was carried out with the BacT/Alert 3D System ver. 4.00D (bioMerieux Japan Ltd., Tokyo, Japan) using both the PF and the SN bottles. At 48 hrs of incubation, the System showed the positive sign only in the anaerobic SN bottle for bacterial growth. The strain isolated from the SN bottle was morphologically, biochemically, and genetically characterized, and finally identified as Capnocytophaga sputigena. The causative Capnocytophaga sputigena isolate was found to be a beta-lactamase-producer demonstrating to possess cfxA3 gene. The gene responsible for the production of CfxA3-beta-lactamase was proved to be chromosome-encoded, by means of southern hybridization analysis. This was the first case of bacteremia caused by chromosome-encoded CfxA3-beta-lactamase-producing Capnocytophaga sputigena.

Evaluation of BacT/Alert 3D SA bottles for accurate detection of Mycobacteremia with special reference to Mycobacterium abscessus

Bacteremia due to Mycobacterium abscessus, a rapid grower, belonging to the Runyon group IV, occurred in an inpatient with fever of unidentified origin in Shinshu University Hospital. To the best of our knowledge, this is the first documented case of M. abscessus bacteremia in Japan. The organism initially grew on Sheep blood agar plates after terminal-subculturing from the BacT/Alert SA aerobic blood culture bottles with no positive signal, and was subsequently identified as M. abscessus using 16S rRNA sequence analysis. We evaluated the BacT/Alert SA bottles for the detection of Mycobacterium species, with special reference to the rapid growers including M. abscessus by seeding experiments and obtained the following findings: 1) The BacT/Alert system shows the positive sign when the bacterial cell counts reach around 10(6) to 10(7) CFU/ml. 2) The System requires around 6 to 7 days of incubation to obtain a sufficient bacterial growth for the positive signal. 3) The System may result in false negative under the 5-day-culture method recommended by American Society for Microbiology in cases of using automated blood culture systems. 4) So-called the blind- or terminal-subcultures from the bottles are inevitable to perform for precluding the false negative cases.

First isolation of Dysgonomonas mossii from intestinal juice of a patient with pancreatic cancer

BACKGROUND

Dysgonomonas species were first designated in 2000. However, clinical infections due to this microorganism have rarely been described. Our aim was to present the first isolation of Dysgonomonas mossii from intestinal juice of a patient with pancreatic cancer.

METHODS

Predominantly appearing grayish-white colonies grown on chocolate and sheep blood agar plates were characterized morphologically by Gram stain, biochemically by automated instrument using Vitek II ID-GNB card together with commercially available kit systems, ID-Test HN-20 and API rapid ID 32A32A, and genetically by sequencing the 16S rRNA gene of the organism using a Taq DyeDeoxy Terminator Cycle Sequencing and a model 3100 DNA sequencer instrument. The isolate was further characterized by antimicrobial susceptibility using MicroFast 4J Panels and additional biochemical and physiological properties.

RESULTS

The isolate was finally identified as D. mossii from the findings of the morphological, cultural, and biochemical properties together with the comparative sequence of the 16S rRNA genes. The isolate was highly susceptible to many antibiotics but resistant to penicillins and cephems.

CONCLUSIONS

As D. mossii was rarely encountered in the clinical microbiology laboratory, it may be misidentified as an X-factor-dependent Haemophilus species due to its negative result for the porphyrin test. Accumulation of the case reports with the isolation of this species is expected to elucidate the infections due to D. mossii. The presence of D. mossii caused no significant clinical infection despite repeated isolations, as the patient had no conspicuous abdominal complaints. However, our report is a noteworthy and useful piece of information.