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Serratia marcescens swarms at 30[degrees]C but not at 37[degrees]C on a nutrient-rich (LB) agar surface. Mini-Tn5 mutagenesis ors. marcescens CH-1 yielded a mutant (WC100) that swarms not only vigorously at 37[degrees]C but also earlier and faster than the parent strain swarms at 30[degrees]C. Analysis of this mutant revealed that the transposon was inserted into a gene (rssA) predicted to encode a bacterial two-component signal transduetion sensor Mnase, upstream of which a potential response regulator gene (rssB) was located, rssA and rssB insertiondeletion mutants were constructed through homologous recombination, and the two mutants exhibited similar swarming phenotypes on LB swarming agar, in which swarming not only occurred at 37[degrees]C but also initiated at a lower cell density, on a surface with a higher agar concentration, and more rapidly than the swarming of the parent strain at 30[degrees]C. Both mutants also exhibited increased hemolysin activity and altered cell surface topologies compared with the parent CH-I strain. Temperature and certain saturated fatty acids (SFAs) were found to negatively regulate S. mareescens swarming via the action of RssA-RssB. Analysis of the fatty acid profiles of the parent and the rssA and rssB mutants grown at 30[degrees]C or 37[degrees]C and under different nutrition conditions revealed a relationship between cellular fatty acid composition and swarming phenotypes. The cellular fatty acid profile was also observed to be affected by RssA and RssB. SFA-dependent inhibition of swarming was also observed in Proteus mirabilis, suggesting that either SFAs per se or the modulation of cellular fatty acid composition and hence homeostasis of membrane fluidity may be a conserved mechanism for regulating swarming motility in gram-negative bacteria.

Hfq is a bacterial RNA chaperone involved in the riboregulation of diverse genes via small noncoding RNAs. Here, we show that Hfq is critical for the uropathogenic Proteus mirabilis to effectively colonize the bladder and kidneys in a murine urinary tract infection (UTI) model and to establish burned wound infection of the rats. In this regard, we found the hfq mutant induced higher IL-8 and MIF levels of uroepithelial cells and displayed reduced intra-macrophage survival. The loss of hfq affected bacterial abilities to handle H2O2 and osmotic pressures and to grow at 50°C. Relative to wild-type, the hfq mutant had reduced motility, fewer flagella and less hemolysin expression and was less prone to form biofilm and to adhere to and invade uroepithelial cells. The MR/P fimbrial operon was almost switched to the off phase in the hfq mutant. In addition, we found the hfq mutant exhibited an altered outer membrane profile and had higher RpoE expression, which indicates the hfq mutant may encounter increased envelope stress. With the notion of envelope disturbance in the hfq mutant, we found increased membrane permeability and antibiotic susceptibilities in the hfq mutant. Finally, we showed that Hfq positively regulated the RpoS level and tolerance to H2O2 in the stationary phase seemed largely mediated through the Hfq-dependent RpoS expression. Together, our data indicate that Hfq plays a critical role in P. mirabilis to establish UTIs by modulating stress responses, surface structures and virulence factors. This study suggests Hfq may serve as a scaffold molecule for development of novel anti-P. mirabilis drugs and P. mirabilis hfq mutant is a vaccine candidate for preventing UTIs. [ABSTRACT FROM AUTHOR]

Hfq is a bacterial RNA chaperone involved in the riboregulation of diverse genes via small noncoding RNAs. Here, we show that Hfq is critical for the uropathogenic Proteus mirabilis to effectively colonize the bladder and kidneys in a murine urinary tract infection (UTI) model and to establish burned wound infection of the rats. In this regard, we found the hfq mutant induced higher IL-8 and MIF levels of uroepithelial cells and displayed reduced intra-macrophage survival. The loss of hfq affected bacterial abilities to handle H2O2 and osmotic pressures and to grow at 50°C. Relative to wild-type, the hfq mutant had reduced motility, fewer flagella and less hemolysin expression and was less prone to form biofilm and to adhere to and invade uroepithelial cells. The MR/P fimbrial operon was almost switched to the off phase in the hfq mutant. In addition, we found the hfq mutant exhibited an altered outer membrane profile and had higher RpoE expression, which indicates the hfq mutant may encounter increased envelope stress. With the notion of envelope disturbance in the hfq mutant, we found increased membrane permeability and antibiotic susceptibilities in the hfq mutant. Finally, we showed that Hfq positively regulated the RpoS level and tolerance to H2O2 in the stationary phase seemed largely mediated through the Hfq-dependent RpoS expression. Together, our data indicate that Hfq plays a critical role in P. mirabilis to establish UTIs by modulating stress responses, surface structures and virulence factors. This study suggests Hfq may serve as a scaffold molecule for development of novel anti-P. mirabilis drugs and P. mirabilis hfq mutant is a vaccine candidate for preventing UTIs. [ABSTRACT FROM AUTHOR]

Two strains of Chryseobacterium identified from different experiments are proposed to represent new species. Strain WLa1L2M3 T was isolated from the digestive tract of an Oryctes rhinoceros beetle larva. Strain 09-1422 T was isolated from a cage housing the stick insect Eurycantha calcarata . Sequence analysis of the 16S rRNA and rpoB genes found both strains to be similar but not identical to other Chryseobacterium species. Whole-genome sequencing suggested the isolates represent new species, with average nucleotide identity values ranging from 74.6 to 80.5 %. Genome-to-genome distance calculations produced values below 25.3 %, and digital DNA-DNA hybridization values were 13.7-29.9 %, all suggesting they are distinct species. The genomic DNA G+C content of WLa1L2M3 T is approximately 32.53 %, and of 09-1422 T is approximately 35.89 %. The predominant cellular fatty acids of strain WLa1L2M3 T are C 15 : 0 iso, summed feature 9 (C 16 : 0 10OH or C 17 : 1 iso ω6 c ), C 17 : 0 iso 3OH, summed feature 3 (C 16 : 1 ω7 c and/or C 16 : 1 ω6c), C 15 : 0 iso 3OH, C 15 : 0 anteiso and C 13 : 0 iso, and those of strain 09-1422 T are C 15 : 0 iso, summed feature 3 (C 16 : 1 ω7c and/or C 16 : 1 ω6 c ), C 17 : 0 iso 3OH, C 15 : 0 anteiso, C 15 : 0 iso 3OH, C 16 : 1 ω7 c , C 17 : 0 2OH and C 18 : 0 . In addition, physiological and biochemical tests revealed phenotypic differences from related Chryseobacterium type strains. These cumulative data indicate that the two strains represent novel species of the genus Chryseobacterium for which the names Chryseobacterium oryctis sp. nov. and Chryseobacterium kimseyorum sp. nov. are proposed with WLa1L2M3 T (=BCRC 81350 T =JCM 35215 T =CIP 112035 T ) and 09-1422 T (=UCDFST 09-1422 T =BCRC 81359 T =CIP 112165 T ), as type strains, respectively.

Background and Purpose: Disseminated intravascular coagulation (DIC) is a rarely described finding in invasive pulmonary aspergillosis (IPA) with unclear impact on mortality., Methods: This study included patients with positive cultures of Aspergillus spp. from respiratory specimens, serological evidence of aspergillosis, or lung biopsy findings supporting aspergillosis treated at National Taiwan University Hospital from January 1999 to June 2005. IPA was defined based on the consensus of the European Organization for Research and Treatment of Cancer, and the Mycosis Study Group of the National Institute of Allergy and Infectious Diseases. Univariate logistic regression analysis was used to evaluate the factors associated with mortality., Results: Proven or probable IPA was diagnosed in 26 patients. Hematological malignancy was found in 11 patients (42%) and immunosuppressive agents had been administered to 17 patients (65%). Among 20 culture-proven infections (77%), the most frequently encountered fungi were Aspergillus fumigatus (46%) and Aspergillus flavus (23%). The overall mortality rate was 62%. Univariate and multivariate analyses revealed that DIC was the only factor that was significantly associated with death attributable to IPA (p<0.01)., Conclusions: IPA is associated with a high mortality rate, particularly for patients with DIC.

We describe a case of empyema thoracis caused by Rhizopus oryzae diagnosed in an allogenic bone marrow transplant patient with acute lymphocytic leukemia. The isolate of R. oryzae was recovered from three pleural effusion specimens, which were black in color. It was identified on the basis of characteristic colonial appearance and microscopic findings, as well as the partial sequencing of rRNA genes. The patient died of uncontrolled R. oryzae empyema thoracis and concomitant nosocomial infection.

Escherichia coli strains are among the major bacterial causes of diarrheal illness. At least 5 categories of diarrheagenic E. coli (DEC) are recognized, namely enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC), enteroinvasive E. coli (EIEC), enteroaggregative E. coli (EAEC), and enterohemorrhagic E. coli (EHEC). Due to the need for costly and labor-intensive diagnostic procedures, identification of DEC is difficult at standard laboratories. Therefore, the epidemiology of DEC infections remains obscure in Taiwan. Recently, polymerase chain reaction (PCR) or dot blot has been used for genetic detection of DEC. In this study, we analyzed 150 E. coli isolates from diarrheal stools of children under 5 years old. The PCR tests detected 5 ETEC (3.3%), 6 EPEC (4%), 4 EIEC (2.7%), and 13 EAEC (8.7%) isolates. No EHEC was detected. Dot blot and sequence analysis were used to confirm the results of PCR. The cellular fatty acid (CFA) profiles from E. coli isolates were also analyzed. Comparison of CFA composition revealed minor variation in the percentage of each fatty acid detected among DEC isolates of ETEC, EPEC, EIEC and EAEC, but did not provide enough evidence for differentiating between categories of DEC by CFA profiles alone.

Background and Purpose: Stenotrophomonas maltophilia, a major pathogen causing nosocomial infection, is inherently resistant to multiple antimicrobial agents. Evaluation of the effectiveness of recommended therapeutic options for S. maltophilia infections is crucial, particularly in areas with high antimicrobial resistance in this nosocomial pathogen., Methods: The in vitro activities of ceftazidime (CAZ), ticarcillin-clavulanate (TIM), amikacin (AN), ciprofloxacin (CIP), and trimethoprim-sulfamethoxazole (TMP-SMZ) against 102 clinical isolates of S. maltophilia collected from January 1998 to December 1999 at a university hospital were evaluated. The disk diffusion and agar dilution susceptibilities of individual agents against these isolates were determined concomitantly. Errors between results obtained by the two methods were identified based on the guidelines for Acinetobacter species provided by the National Committee for Clinical Laboratory Standards. Activities of three two-drug combinations (AN + CIP, CAZ + CIP, and TIM + TMP-SMZ) against 32 of these isolates were analyzed using the checkerboard synergy test., Results: Among the agents tested, TMP-SMZ was the most active against S. maltophilia (83.3% susceptible), followed by CIP (63.7%), CAZ (39.2%), TIM (36.2%), and AN (20.5%). Errors (very major and major) between the results obtained by the disk diffusion and agar dilution methods occurred at a high frequency for AN (15% and 3%), CAZ (8% and 6%), and CIP (3% and 3%). Synergy or partial synergy of antimicrobial agent combinations was detected predominantly with CAZ + CIP (81.3%) and TIM + TMP-SMZ (84.4%) but not with AN + CIP (37.5%). No antagonism was detected with any drug combinations., Conclusion: The dilution method is preferable to the disk diffusion method for susceptibility testing of S. maltophilia isolates, particularly for testing with AN, CAZ, and TIM, which have considerable error rates between the results obtained by the two methods. The findings from the synergy test suggest that TIM + TMP-SMZ and CAZ + CIP combinations are the treatments of choice for infections caused by S. maltophilia.