Differential effects of the Akt pathway on the internalization of Klebsiella by lung epithelium and macrophages.

Host response to lung infection includes coordinated efforts of multiple cell types, including the lung epithelium and macrophages. Importantly, both the lung epithelium and macrophages can internalize and clear invading pathogens. However, the mechanisms and their ability to internalize or phagocytose differ. Akt is a key cellular pathway that controls cell proliferation and survival, in addition to its role in host defense. The role of the Akt pathway was assessed using pharmacological Akt modulators in lung epithelial (A549) and macrophage (RAW 264.7) cell lines during Klebsiella bacterial infection. Our data show that the inhibition of the Akt pathway using specific Akt inhibitor MK2206 increased the phagocytic ability of lung epithelial cells but not of macrophages. In contrast, the activation of Akt using specific activator SC-79 decreased the phagocytic ability of epithelial cells, while it increased the phagocytic ability of macrophages. The altered phagocytic ability in both cell types using Akt modulators was not due to changes in bacterial adhesion to the host cell. The clinical usefulness of these Akt modulators may vary based on the type of infection and on the relative contribution of epithelial cells and macrophages in clearing the particular bacterial infection. The Akt pathway has differential roles in the internalization of Klebsiella bacteria by respiratory epithelial cells and immune cells.

Alterations of gut microbiome accelerate multiple myeloma progression by increasing the relative abundances of nitrogen-recycling bacteria.

BACKGROUND: Gut microbiome alterations are closely related to human health and linked to a variety of diseases. Although great efforts have been made to understand the risk factors for multiple myeloma (MM), little is known about the role of the gut microbiome and alterations of its metabolic functions in the development of MM. RESULTS: Here, in a cohort of newly diagnosed patients with MM and healthy controls (HCs), significant differences in metagenomic composition were discovered, for the first time, with higher bacterial diversity in MM. Specifically, nitrogen-recycling bacteria such as Klebsiella and Streptococcus were significantly enriched in MM. Also, the bacteria enriched in MM were significantly correlated with the host metabolome, suggesting strong metabolic interactions between microbes and the host. In addition, the MM-enriched bacteria likely result from the regulation of urea nitrogen accumulated during MM progression. Furthermore, by performing fecal microbiota transplantation (FMT) into 5TGM1 mice, we proposed a mechanistic explanation for the interaction between MM-enriched bacteria and MM progression via recycling urea nitrogen. Further experiments validated that Klebsiella pneumoniae promoted MM progression via de novo synthesis of glutamine in mice and that the mice fed with glutamine-deficient diet exhibited slower MM progression. CONCLUSIONS: Overall, our findings unveil a novel function of the altered gut microbiome in accelerating the malignant progression of MM and open new avenues for novel treatment strategies via manipulation of the intestinal microbiota of MM patients. Video abstract.

The changing epidemiology of genital ulcer disease in South Africa: has donovanosis been eliminated?

OBJECTIVES: We used an in-house molecular assay for the detection of Klebsiella granulomatis in ulcer specimens collected over a 12-year surveillance period in order to determine whether a diagnosis of donovanosis could be ascribed to genital ulcer disease (GUD) of unknown aetiology in our setting. METHODS: Between 2007 and 2018, a total of 974 genital ulcer specimens with no previously identified sexually transmitted (STI) pathogens were selected from STI aetiological surveys conducted in all nine provinces of South Africa. Giemsa-stained ulcer smears from the same participants had previously been routinely analysed for the presence of typical Donovan bodies within large mononuclear cells. A Klebsiella screening assay targeting the phoE (phosphate porin) gene was used in combination with restriction digest analysis and sequencing to confirm the presence of K. granulomatis. RESULTS: The Klebsiella screening assay tested positive in 19/974 (2.0%) genital ulcer specimens. Restriction digest analysis and nucleotide sequencing of the phoE gene confirmed that none of these specimens was positive for K. granulomatis DNA. Similarly, Donovan bodies were not identified in the Giemsa stained ulcer smears of these specimens. CONCLUSIONS: This is the first study to assess K. granulomatis as a cause of genital ulceration in South Africa over a 12-year surveillance period using molecular methods. The results demonstrate that K. granulomatis is no longer a prevalent cause of GUD in our population.

Klebsiella variicola and Klebsiella quasipneumoniae with capacity to adapt to clinical and plant settings / Klebsiella variicola y Klebsiella quasipneumoniae con capacidad para adaptarse al ambiente clínico y a las plantas

Abstract: Objective: To compare the genetic determinants involved in plant colonization or virulence in the reported genomes of K. variicola, K. quasipneumoniae and K. pneumoniae. Materials and methods: In silico comparisons and Jaccard analysis of genomic data were used. Fimbrial genes were detected by PCR. Biological assays were performed with plant and clinical isolates. Results: Plant colonization genes such as cellulases, catalases and hemagglutinins were mainly present in K. variicola genomes. Chromosomal β-lactamases were characteristic of this species and had been previously misclassified. K. variicola and K. pneumoniae isolates produced plant hormones. Conclusions: A mosaic distribution of different virulence- and plant-associated genes was found in K. variicola and in K. quasipneumoniae genomes. Some plant colonizing genes were found mainly in K. variicola genomes. The term plantanosis is proposed for plant-borne human infections.

Resumen: Objetivo: Comparar genes de colonización de plantas o de virulencia en los genomas reportados de K. variicola, K. quasipneumoniae y K. pneumoniae. Material y métodos: Se utilizaron análisis in silico y de Jaccard. Por PCR se detectaron genes de fimbrias. Se realizaron ensayos biológicos con aislados de plantas y clínicos. Resultados: Los genes de colonización de plantas como celulasas, catalasas y hemaglutininas se encontraron principalmente en genomas de K. variicola. Las β-lactamasas cromosómicas son características de la especie y en algunos casos estaban mal clasificadas. K. variicola y K. pneumoniae producen hormonas vegetales. Conclusiones: Se encontró una distribución en mosaico de los genes de asociación con plantas y de virulencia en K. variicola y K. quasipneumoniae. Principalmente en K. variicola se encontraron algunos genes involucrados en la colonización de plantas. Se propone el término plantanosis para las infecciones humanas de origen vegetal.

Hospital-acquired infections at an oncological intensive care cancer unit: differences between solid and hematological cancer patients.

BACKGROUND: Cancer patients have a higher risk of severe sepsis in comparison with non-cancer patients, with an increased risk for hospital-acquired infections (HAI), particularly with multidrug resistant bacteria (MDRB). The aim of the study is to describe the frequency and characteristics of HAI and MDRB in critically ill cancer patients. METHODS: We conducted an 18-month prospective study in patients admitted ≥48 h to an ICU at a cancer referral center in Mexico. Patients with hematological malignancies (HM) were compared with solid tumors. Demographic and clinical data were recorded. Mortality was evaluated at 30-days. RESULTS: There were 351 admissions during the study period, among whom 157 (66 %) met the inclusion criteria of the study as follows: 104 patients with solid tumors and 53 with HM. Sixty-four patients (40.7 %) developed 95 episodes of HAI. HAI rate was 4.6/100 patients-days. MDRB were isolated in 38 patients (24 %), with no differences between both groups. Escherichia coli was the main bacteria isolated (n = 24), 78 % were extended spectrum beta-lactamases producers. The only risk factor associated with HAI was the presence of mechanical ventilation for more than 5 days (OR 3.12, 95 % CI 1.6 - 6.2, p = 0.001). At 30-day follow-up, 61 patients (39 %) have died (38 % with solid tumors and 60 % with HM, p < 0.001). No differences were found in mortality at 30-day between patients with HAI (n = 25, 39 %) vs. non-HAI (n = 36, 38.7 %, p = 0.964); neither in those who developed a HAI with MDRB (n = 12, 35.3 %) vs. HAI with non-MDRB (n = 13, 43.3 %, p = 0.51). CONCLUSIONS: Patients with cancer who are admitted to an ICU, have a high risk of HAI, but there were no differences patients with solid or hematologic malignancies.

Enterobacter and Klebsiella species isolated from fresh vegetables marketed in Valencia (Spain) and their clinically relevant resistances to chemotherapeutic agents.

Occurrence of antibiotic-resistant pathogenic or commensal enterobacteria in marketed agricultural foodstuffs may contribute to their incorporation into the food chain and constitutes an additional food safety concern. In this work, we have determined the clinically relevant resistances to 11 common chemotherapeutic agents in Enterobacter and Klebsiella isolates from fresh vegetables from various sources (supermarkets and greengrocers' shops in Valencia, Spain). A total of 96 isolates were obtained from 160 vegetables analyzed (50% positive samples): 68 Enterobacter isolates (59 E. cloacae, two E. aerogenes, two E. cancerogenus, one E. gergoviae, and four E. sakazakii, currently Cronobacter spp.), and 28 Klebsiella isolates (19 K. oxytoca and 9 K. pneumoniae). Only seven isolates were susceptible to all agents tested, and no resistances to ceftazidime, ciprofloxacin, gentamicin, and chloramphenicol were detected. Most isolates were resistant to amoxicillin/clavulanic acid (74 [58 Enterobacter and 16 Klebsiella]) or to ampicillin (80 [55/25]). Other resistances were less frequent: nitrofurantoin (13 isolates [12/1]), tetracycline (6 [5/1]), co-trimoxazole (3 [3/0]), cefotaxime (1 [1/0]), and streptomycin (2 [1/1]). Multiresistant isolates to two (56 [41/15]), three (10 E. cloacae isolates), four (one E. cloacae and one K. pneumoniae isolate), and five (two E. cloacae isolates) chemotherapeutic agents were also detected. The presence of potential pathogens points to marketed fresh produce, which often is eaten raw, as a risk factor for consumer health. In addition, these results support the usefulness of these bacterial species as indicators of the spreading of antibiotic resistances into the environment, particularly in the food chain, and suggest their role as carriers of resistance determinants from farms to consumers, which may constitute an additional "silent" food safety concern. Therefore, there is a need to improve the hygienic quality of marketed fresh vegetables, from better methods to prevent contamination in the farms to the use of sanitizing practices at home.

Bioaugmentation with cadmium-resistant plant growth-promoting rhizobacteria to assist cadmium phytoextraction by Helianthus annuus.

Micrococcus sp. MU1 and Klebsiella sp. BAM1, the cadmium-resistant plant growth-promoting rhizobacteria (PGPR), produce high levels of indole-3-acetic acid (IAA) during the late stationary phase of their growth. The ability of PGPR to promote root elongation, plant growth and cadmium uptake in sunflowers (Helianthus annuus) was evaluated. Both species of bacteria were able to remove cadmium ions from an aqueous solution and enhanced cadmium mobilization in contaminated soil. Micrococcus sp. and Klebsiella sp. use aminocyclopropane carboxylic acid as a nitrogen source to support their growth, and the minimum inhibitory concentrations of cadmium for Micrococcus sp. and Klebsiella sp. were 1000 and 800mM, respectively. These bacteria promoted root elongation in H. annuus seedlings in both the absence and presence of cadmium compared to uninoculated seedlings. Inoculation with these bacteria was found to increase the root lengths of H. annuus that had been planted in cadmium-contaminated soil. An increase in dry weight was observed for H. annuus inoculated with Micrococcus sp. Moreover, Micrococcus sp. enhanced the accumulation of cadmium in the root and leaf of H. annuus compared to untreated plants. The highest cadmium accumulation in the whole plant was observed when the plants were treated with EDTA following the treatment with Micrococcus sp. In addition, the highest translocation of cadmium from root to the above-ground tissues of H. annuus was found after treatment with Klebsiella sp. in the fourth week after planting. Our results show that plant growth and cadmium accumulation in H. annuus was significantly enhanced by cadmium-resistant PGPRs, and these bacterial inoculants are excellent promoters of phytoextraction for the rehabilitation of heavy metal-polluted environments.

On the evolution of the sexually transmitted bacteria Haemophilus ducreyi and Klebsiella granulomatis.

Haemophilus ducreyi and Klebsiella (Calymmatobacterium) granulomatis are sexually transmitted bacteria that cause characteristic, persisting ulceration on external genitals called chancroid and granuloma inguinale, respectively. Those ulcers are endemic in developing countries or exist, as does granuloma inguinale, only in some geographic "hot spots."H. ducreyi is placed in the genus Haemophilus (family Pasteurellacae); however, this phylogenetic position is not obvious. The multiple ways in which the bacterium may be adapted to its econiche through specialized nutrient acquisitions; defenses against the immune system; and virulence factors that increase attachment, fitness, and persistence within genital tissue are discussed below. The analysis of K. granulomatis phylogeny demonstrated a high degree of identity with other Klebsiella species, and the name K. granulomatis comb. nov. was proposed. Because of the difficulty in growing this bacterium on artificial media, its characteristics have not been sufficiently defined. More studies are needed to understand bacterial genetics related to the pathogenesis and evolution of K. granulomatis.

Aerobic bacterial isolates from choledochal bile at a tertiary hospital.

We studied the aerobic bacterial isolates from bile and their susceptibilty pattern in patients with biliary tract disease. Samples of bile collected during endoscopic retrograde cholangio pancreatography (ERCP) and surgery, were inoculated on standard media. Bacterial identification and susceptibility were done by standard techniques. A total of 209 samples were cultured, out of which 128 samples showed growth. Total number of isolates obtained was 221. Poly-microbial infection was detected in 67 patients. Predominant aerobic bacterial isolates obtained were Escherichia coli 30% (67), Klebsiella species 23.98% (53), Enterococcus species 12.21% (27). Multi-drug resistance was noted in 57%. Higher resistance rate was noted among Gram negative bacilli for ampicillin (92.4%), cephalexin (82.46%), ciprofloxacin (68.42%), piperacillin (64.33%). Sensitivity to meropenem was 90.64% and amikacin was 76.61%. Gram positive bacteria showed high resistance to gentamicin (39.53%). Sensitivity to ampicillin was 86.05% and penicillin was 81.4%. Vancomycin and teicoplanin showed 100% sensitivity. From our study we conclude that E. coli, Klebsiella species and Enterococcus species are common pathogens infecting biliary tract. Poly-microbial infection and multi-drug resistance warrants culture and sensitivity to guide antimicrobial therapy. We recommend combination of amikacin and ampicillin for empirical therapy at our institution.

[Experimental and mathematical modeling of population dynamics of rhizospheric bacteria under conditions of cadmium stress].

The method of membrane filters was used to study the population dynamics of bacteria belonging to the genera Arthrobacter, Flavobacterium, and Klebsiella in barley (Hordeum vulgare) rhizosphere under conditions of cadmium stress (5-15 mg Cd/g soil). Mathematical modeling allowed us to demonstrate that the phytoprotective effect is implemented via the following succession of events: the bacteria synthesize phytohormones (IAA and ethylene)-->root excretory activity increases-->the number of the bacteria in the rhizoplane grows-->the flux of bacteria migrating from the rhizoplane to the rhizosphere increases-->the number of bacteria binding cadmium ions in the rhizosphere grows-->the amount of free ions entering the plant decreases. Among the bacteria studied, K. mobilis 880 displayed the highest migration and immobilization activity and the best survival rate under conditions of cadmium stress. Consequently, K. mobilis 880 is recommended for use in biopreparations for stimulating plant growth under conditions of heavy metal pollution.

Tissue antioxidant capacity and bacterial translocation under total parenteral nutrition.

Alterations in the antioxidative system have been observed during total parenteral nutrition (TPN). Light exposure or changes in the composition of TPN formulas may affect this system. Bacterial translocation (BT) is frequent under TPN and may be related to oxidative status. The aim of this study was to determine the adverse effects of standard and glutamine-enriched TPN, with or without light exposure, on oxidative status (liver and kidney-reduced glutathione, GSH) and its relationship to BT. Thirty-three adult Wistar rats underwent central-venous cannulation and were randomly assigned to one of four groups receiving different TPN regimes for 10 days. The TPN group (n = 10) had standard TPN, the TPN(-) group (n = 8) standard TPN without light exposure, the GTPN group (n = 8) glutamine-enriched TPN, and the GTPN(-) group (n = 7) glutamine-enriched TPN without light exposure. A sham group (n = 16) receiving chow and water ad libitum and saline i.v. served as controls. At the end of the experiment, GSH was determined in liver and kidney tissue. Mesenteric lymph nodes and peripheral and portal blood samples were cultured for BT. Compared to sham rats, TPN groups had statistically significant lower GSH levels, but there were no differences between standard or glutamine-enriched groups or light-exposure groups. Sham animals had 12% BT. Significantly higher BT (P < 0.05) occurred in TPN rats: 70% in the TPN group, 88% in the TPN(-) group, 86% in GTPN (-) animals, and only 50% in the GTPN group (P = 0.06 vs TPN group). In conclusion, (1) TPN reduces antioxidant capacity; (2) glutamine supplementation or light protection does not improve tissue antioxidant capacity under TPN; (3) the absence of light exposure does not improve TPN-related BT; and (4) glutamine supplementation tends to reduce BT only in the presence of light.

Translocação bacteriana para o pulmão na icterícia obstrutiva experimental em ratos / Bacterial translocation to the lung in obstructive jaundice in rats

Objetivo: Tem sido demonstrado que a icterícia obstrutiva provoca depressão do sistema imunológico, mudança no padrão de colonização bacteriana dos intestinos e passagem de bactérias da luz intestinal para a circulação porta e sistêmica. Estudo experimental em ratos procurou observar a possibilidade de translocação bacteriana para os pulmões após a ligadura do colédoco. Método: Foram utilizados 20 ratos Wistar pesando de 178 a 215g, separados aleatoriamente em dois grupos iguais. Nos ratos do grupo I foi feita a ligadura do colédoco e nos do grupo II apenas a manipulação do colédoco com pinça atraumática (sham operation). No sétimo dia de observação os animais foram mortos com superdose de anestésico, sangue foi colhido para dosagem de bilirrubinas e os pulmões ressecados sob condições assépticas. Metade de cada pulmão foi homogeneizada e semeada em meios de cultura ágar McConkey e ágar sangue. A outra metade serviu para exame histopatológico - coloração hematoxilina e eosina. Os dados foram analisados pelo teste t, com significância 0,05. Resultados: Revelaram bilirrubina total em média 18,7ñ3,6 no grupo I e 0,7ñ0,2 no grupo II. No grupo I foram isoladas colônias de Klebsiela sp nos pulmões de 30 por cento dos animais e E. coli em 20 por cento, e os escores histopatológicos atingiram a média 6,2ñ2,08. No grupo II não foram detectadas bactérias nos pulmões e os escores do exame histopatológico atingiram 1,8ñ1,16. A diferença dos dados analisados mostrou-se significativa (p<0,05). Conclusões: Concluiu-se que a icterícia obstrutiva por ligadura do colédoco em ratos provocou translocação de germes Gram-negativos para os pulmões e resultou em alterações histopatológicas significativas

IB-367, a protegrin peptide with in vitro and in vivo activities against the microflora associated with oral mucositis.

Although the microflora associated with oral mucositis initiated by cytotoxic therapy is not well characterized, several studies suggest that reduction of the microbial load in the oral cavity has some clinical benefit. The MICs of IB-367, a synthetic protegrin analog, ranged from 0.13 to 64 microgram/ml for gram-positive bacteria (Streptococcus mitis, Streptococcus sanguis, Streptococcus salivarius, and Staphylococcus aureus) and from 0.06 to 8 microgram/ml for gram-negative species (Klebsiella, Escherichia, and Pseudomonas). IB-367 exhibited rapid, microbicidal activity against both log- and stationary-phase cultures of methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa. At concentrations near the MICs for these two organisms (4 and 2 microgram/ml, respectively), IB-367 reduced viability by more than 3 logs in less than 16 min. Similarly, IB-367 effected a 4-log reduction of the endogenous microflora in pooled human saliva within 2 min at 250 microgram/ml, a concentration readily attained by local delivery. After nine serial transfers at 0.5x the MIC, the MIC of IB-367 for MRSA and P. aeruginosa increased only two to four times. In a phase I clinical study with healthy volunteers, IB-367 was well tolerated, with no detectable systemic absorption. One hour after treatment with 9 mg of IB-367, the prevalence of gram-negative bacteria and yeast was reduced, and the density of the predominant gram-positive oral flora was decreased 1,000 times. IB-367's properties (speed of killing, breadth of spectrum, and lack of resistance) make the compound a strong candidate for the prophylaxis of oral mucositis. Phase II clinical trials with IB-367 are under way for this indication in immunocompromised subjects.

Phylogenetic evidence for reclassification of Calymmatobacterium granulomatis as Klebsiella granulomatis comb. nov.

By sequencing a total of 2089 bp of the 16S rRNA and phoE genes it was demonstrated that Calymmatobacterium granulomatis (the causative organism of donovanosis) shows a high level of identity with Klebsiella species pathogenic to humans (Klebsiella pneumoniae, Klebsiella rhinoscleromatis). It is proposed that C. granulomatis should be reclassified as Klebsiella granulomatis comb. nov. An emended description of the genus Klebsiella is given.

Effect of oral supplementation of ornithine-alpha-ketoglutarate on the intestinal barrier after orthotopic small bowel transplantation.

The aim of this study was to analyze the possible protective effects of a glutamine and arginine precursor (ornithine-alpha-ketoglutarate [OKG]) on the mucosa of a transplanted intestine when administered with either a defined formula oral diet (DFD) or a standard chow. Isogenic male Lewis rats (250 g) were submitted to a laparotomy (groups 1 and 2) or to an orthotopic small bowel transplantation (SBT; groups 3-6). Groups 1, 3, and 5 received a DFD 14 days after surgery. Groups 2, 4, and 6 received standard chow. In addition, groups 5 and 6 received a daily oral supplementation of 1.4 g/kg of OKG. Weight changes and food intake were recorded daily. At the end of the study, bacterial translocation (BT) was measured in mesenteric lymph nodes, liver, and spleen. The protein/DNA index was also determined in intestinal mucosa. SBT induced BT in all transplanted groups, especially in those fed DFD. Addition of OKG (groups 5 and 6) significantly reduced BT in comparison with groups 3 and 4 and improved the protein/DNA index as well as weight gain. It is concluded that OKG supplementation protects the intestinal barrier after SBT, and that this effect is more marked when it is added to a standard chow.

Microbial translocation in neonates and infants receiving long-term parenteral nutrition.

OBJECTIVE: To explore whether episodes of endogenous septicemias due to microbial translocation are clinically relevant in neonates and infants who are receiving long-term parenteral nutrition (PN). DESIGN: Prospective observational cohort study of 2 years. SETTING: Neonates and infants who underwent surgical procedures and required PN because of gastrointestinal abnormalities. MEASUREMENTS: Surveillance cultures of the oropharynx and gut were obtained at the first of PN and thereafter twice each week. These cultures were processed for all microorganisms, except for coagulase-negative staphylococci, in a semiquantitative manner to detect overgrowth. A blood sample was taken for culture from both the central venous line and peripheral vein on clinical indication only. Microbial translocation was diagnosed when the microorganisms that were isolated from the blood sample were also carried in the throat and/or rectum within the 2 weeks preceding the episode of septicemia. MAIN RESULTS: Of 94 infants, 10 (11%) experienced 24 episodes of septicemia (ie, 7.3 septicemic episodes per 1000 days of PN). Six infants experienced 15 episodes of microbial translocation due to enteric microorganisms, including Escherichia coli, Klebsiella, Candida species, and enterococci. Microbial translocation occurred after a median of 58 days of PN (range, 32 to 286 days). The enteric organisms that caused septicemia were always present in the throat and/or rectum and in high concentrations ( > 10(5) colony-forming units per gram [ie, overgrowth]) in 60% of the translocation episodes. All but one episode occurred in infants with an abnormal serum bilirubin level ( > 17 mumol/L [0.99 mg/dl]). CONCLUSIONS: In neonates and infants who are receiving PN, septicemia may be a gut-related phenomenon.

Serotypes, hemagglutinins, siderophore synthesis, and serum resistance of Klebsiella isolates causing human urinary tract infections.

A total of 146 Klebsiella isolates from human asymptomatic bacteriuria (n = 73), cystitis (n = 54), and acute pyelonephritis (n = 19) were examined for the presence of particular virulence factors. Capsular type K2 was the most common serotype observed (13%). This capsule type was prevalent in isolates from asymptomatic bacteriuria and cystitis but not from pyelonephritis. Type 1 fimbriae were found significantly more often in pyelonephritis isolates than among those from asymptomatic and symptomatic lower urinary tract infection (UTI; P < .05), while no marked differences were detected with respect to the distribution of type 3 fimbriae. Serum resistance was more frequent among isolates from symptomatic (26%) than from asymptomatic UTI (18%). Enterochelin was produced by all but 1 of the isolates as determined by a bioassay. In contrast, aerobactin synthesis was rare (3%), with isolates from pyelonephritis showing the highest frequency of aerobactin production (3/19).

Bacterial adherence to hydrophilic polymer-coated polyurethane stents.

Biliary stent blockage by adherence of bacteria and formation of biofilm is a major problem in endoscopic stenting procedures. We have investigated bacterial adherence to hydrophilic polymer (Hydromer)-coated polyurethane stents in stationary and perfusion experiments. Adherence of gram negative and gram positive organisms under stationary conditions was similar between Hydromer-coated and non-coated control polyurethane stents; however, a marked 1 to 3 log reduction in adherence to Hydromer-coated stents occurred when perfusion experiments in phosphate buffer solution or bile were performed. The results suggest that Hydromer-coated polyurethane stents could be useful in preventing complications caused by biliary stent blockage.

Fimbriation, capsulation, and iron-scavenging systems of Klebsiella strains associated with human urinary tract infection.

Thirty-two strains of Klebsiella pneumoniae and seven strains of Klebsiella oxytoca isolated from urinary tract infections in elderly adults were analyzed for capsular antigens, iron-scavenging systems, and fimbriation. All strains were capsulated. Twenty-seven different K antigens were identified among the strains, with no particular antigen dominating. All strains produced the iron-scavenging system enterochelin as analyzed by bioassay and DNA hybridization. In contrast, the aerobactin iron-sequestering system was not detected in any of the strains. All strains caused hemagglutination of tannin-treated human erythrocytes and reacted with an anti-type 3 fimbriae antiserum as well as in DNA hybridization with a type 3 fimbria-specific probe, indicating that the Klebsiella strains possessed this fimbrial type. Possession of type 1 fimbriae was analyzed by agglutination tests and by hybridization with DNA probes from two distinct Klebsiella type 1 fimbria gene clusters. Phenotypic expression of the type 1 fimbriae was found in 29 of 32 K. pneumoniae strains, whereas 30 strains reacted with either of the two type 1 fimbrial cluster DNA probes. In K. oxytoca, however, only three of seven strains expressed type 1 fimbriae and reacted with the DNA probes. The type 3 fimbriae were found to bind to a fraction of epithelial cells exfoliated in normal human urine, whereas the type 1 fimbriae bound strongly to urinary slime. No inhibitors of type 3 fimbrial binding were detected in human urine.