RESUMEN
Morganella psychrotolerans is a histamine-producing bacterium that causes histamine poisoning. In this study, we isolated and characterized a novel phage, MopsHU1, that infects M. psychrotolerans. MopsHU1 is a podovirus with a limited host spectrum. Genomic analysis showed that MopsHU1 belongs to the family Autographiviridae, subfamily Studiervirinae, and genus Kayfunavirus. Comparative analysis revealed that the MopsHU1 genome is similar to those of Citrobacter phage SH3 and Cronobacter phage Dev2. Moreover, the Escherichia coli phage K1F genome is also similar, except for its tailspike gene sequence. These results expand our understanding of the Kayfunavirus phages that infect Morganella spp. Note: The nucleotide sequence data reported here are available in the DDBJ/EMBL/GenBank database under the accession number LC799501.
Asunto(s)
Bacteriófagos , Genoma Viral , Morganella , Filogenia , Bacteriófagos/genética , Bacteriófagos/aislamiento & purificación , Bacteriófagos/clasificación , Bacteriófagos/fisiología , Morganella/virología , Morganella/genética , Genómica , Especificidad del Huésped , Podoviridae/genética , Podoviridae/aislamiento & purificación , Podoviridae/clasificación , Análisis de Secuencia de ADN , Secuencia de BasesRESUMEN
Larval habitats of blood-feeding stable flies, Stomoxys calcitrans (L.) (Diptera: Muscidae), overlap with foraging sites of black blow flies, Phormia regina (Meigen) (Diptera: Calliphoridae). We tested the hypothesis that bacteria in blow fly excreta inform oviposition decisions by female stable flies. In laboratory 2-choice bioassays, we offered gravid female stable flies fabric-covered agar plates as oviposition sites that were kept sterile or inoculated with either a blend of 7 bacterial strains isolated from blow fly excreta (7-isolate-blend) or individual bacterial isolates from that blend. The 7-isolate-blend deterred oviposition by female stable flies, as did either of 2 strains of Morganella morganii subsp. sibonii. Conversely, Exiguobacterium sp. and Serratia marcescens each prompted oviposition by flies. The flies' oviposition decisions appear to be guided by bacteria-derived semiochemicals as the bacteria could not be physically accessed. Oviposition deterrence caused by semiochemicals of the 7-isolate-blend may help stable flies avoid competition with blow flies. The semiochemicals of bioactive bacterial strains could be developed as trap lures to attract and capture flies and deter their oviposition in select larval habitats.
Asunto(s)
Morganella , Muscidae , Femenino , Animales , Calliphoridae , Oviposición , Larva , Bacterias , FeromonasRESUMEN
BACKGROUND: Morganella spp are opportunistic pathogens involved in various infections. Intrinsic resistance to multiple antibiotics (including colistin) combined with the emergence of carbapenemase producers reduces the number of active antimicrobials. The aim of this study was to characterise genetic features related to the spread of carbapenem-resistant Morganella spp. METHODS: This comparative genomic study included extensively drug-resistant Morganella spp isolates collected between Jan 1, 2013, and March 1, 2021, by the French National Reference Center (NRC; n=68) and European antimicrobial resistance reference centres in seven European countries (n=104), as well as one isolate from Canada, two reference strains from the Pasteur Institute collection (Paris, France), and two colistin-susceptible isolates from Bicêtre Hospital (Kremlin-Bicêtre, France). The isolates were characterised by whole-genome sequencing, antimicrobial susceptibility testing, and biochemical tests. Complete genomes from GenBank (n=103) were also included for genomic analysis, including phylogeny and determination of core genomes and resistomes. Genetic distance between different species or subspecies was performed using average nucleotide identity (ANI). Intrinsic resistance mechanisms to polymyxins were investigated by combining genetic analysis with mass spectrometry on lipid A. FINDINGS: Distance analysis by ANI of 275 isolates identified three groups: Morganella psychrotolerans, Morganella morganii subspecies sibonii, and M morganii subspecies morganii, and a core genome maximum likelihood phylogenetic tree showed that the M morganii isolates can be separated into four subpopulations. On the basis of these findings and of phenotypic divergences between isolates, we propose a modified taxonomy for the Morganella genus including four species, Morganella psychrotolerans, Morganella sibonii, Morganella morganii, and a new species represented by a unique environmental isolate. We propose that M morganii include two subspecies: M morganii subspecies morganii (the most prevalent) and M morganii subspecies intermedius. This modified taxonomy was supported by a difference in intrinsic resistance to tetracycline and conservation of metabolic pathways such as trehalose assimilation, both only present in M sibonii. Carbapenemase producers were mostly identified among five high-risk clones of M morganii subspecies morganii. The most prevalent carbapenemase corresponded to NDM-1, followed by KPC-2, and OXA-48. A cefepime-zidebactam combination was the most potent antimicrobial against the 172 extensively drug-resistant Morganella spp isolates in our collection from different European countries, which includes metallo-ß-lactamase producers. Lipid A analysis showed that the intrinsic resistance to colistin was associated with the presence of L-ARA4N on lipid A. INTERPRETATION: This global characterisation of, to our knowledge, the widest collection of extensively drug-resistant Morganella spp highlights the need to clarify the taxonomy and decipher intrinsic resistance mechanisms, and paves the way for further genomic comparisons. FUNDING: None.
Asunto(s)
Antibacterianos , Proteínas Bacterianas , Infecciones por Enterobacteriaceae , Genoma Bacteriano , Pruebas de Sensibilidad Microbiana , Morganella , Filogenia , beta-Lactamasas , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , beta-Lactamasas/genética , beta-Lactamasas/metabolismo , Antibacterianos/farmacología , Genoma Bacteriano/genética , Humanos , Infecciones por Enterobacteriaceae/microbiología , Infecciones por Enterobacteriaceae/epidemiología , Morganella/genética , Genómica , Secuenciación Completa del Genoma , Europa (Continente)/epidemiología , Carbapenémicos/farmacología , Farmacorresistencia Bacteriana Múltiple/genética , Colistina/farmacologíaRESUMEN
The corn snake (Pantherophis guttatus) is a non-venomous snake from the Colubridae family. The pair of scent glands is indispensable in the physiology of reproduction and defense of the species. This structure is located caudal to the cloaca. It is responsible for releasing a thick material based on lipids containing pheromones that perform functions associated with animal behavior and survival. This work aims to report infection by Morganella sp. in a scent gland in a female corn snake, evidencing the diagnosis and treatment. An increase in volume was seen in the final third, proximal to the cloaca, firm consistency, immobile, and approximately 4 cm long and painful to touch. Samples of the material were collected for bacterial culture and antibiogram examination, being positive for bacteria of the genus Morganella. Based on the result of the antibiogram, it was possible to determine the most appropriate therapeutic protocol, with the referral to perform the surgical procedure to remove the tissue compromised by the infection, remaining stable until the removal of the stitches 40 days after the procedure, with total surgical wound healing.(AU)
A corn snake (Pantherophis guttatus) é uma serpente não peçonhenta, da família Colubridae. Na fisiologia da reprodução e defesa da espécie, o par de glândulas de cheiro é indispensável. Essa estrutura está localizada caudal à cloaca e é responsável pela liberação de um material espesso à base de lipídeos, contendo feromônios que exercem funções associadas ao comportamento animal e à sua sobrevivência. O objetivo desse trabalho é relatar uma infecção por Morganella sp. em glândula de cheiro em uma fêmea de corn snake, evidenciando o diagnóstico e tratamento. Observou-se um aumento de volume no terço final, proximal a cloaca, de consistência firme, imóvel e com aproximadamente 4 cm de comprimento e sensibilidade dolorosa ao toque. Foram coletadas amostras do material para cultura bacteriana e exame de antibiograma, sendo positivo para bactérias do gênero Morganella. Com base no resultado do antibiograma, foi possível determinar o protocolo terapêutico mais adequado, como o encaminhamento para realização do procedimento cirúrgico para remoção do tecido comprometido pela infecção, se mantendo estável até a remoção dos pontos, 40 dias após o procedimento, com total cicatrização da ferida cirúrgica.(AU)
Asunto(s)
Animales , Femenino , Colubridae/cirugía , Morganella , Infecciones por Enterobacteriaceae/cirugía , Infecciones por Enterobacteriaceae/diagnóstico , LinfadenitisRESUMEN
Foram padronizados os graus de lesões dos sacos aéreos em perus com aerossaculite, associadas com a presença de isolados de enterobactérias nesses órgãos. Um total de 110 amostras de sacos aéreos de perus machos com aerossaculite foi coletado para o estudo. Durante o processo de abate, as amostras foram coletadas por meio de swabs e submetidas a três métodos de armazenamento (imediato, congelado ou pré-incubado após congelamento) para posterior comparação das suas eficiências de isolamento. Os gêneros da família Enterobacteriaceae foram identificados pelas séries bioquímicas EPM, MILi e citrato de Simmons. O crescimento bacteriano ocorreu em 43,64% das amostras. Neste estudo, quatro padrões de lesões de aerossaculite foram identificados de acordo com as características patológicas dos sacos aéreos. Os principais gêneros de enterobactérias identificadas foram: Escherichia coli, Citrobacter, Proteus, Edwardsiella, Morganella, Kluyvera, Salmonella e Klebsiella. Foi observado que os graus padronizados como 3 e 4 apresentaram maior variedade de gêneros bacterianos. O armazenamento imediato apresentou maior porcentagem de positividade, 41,82%, no entanto o pré-incubado após congelamento se apresentou mais eficaz em relação à quantidade de colônias.(AU)
The degrees of air sac lesions in turkeys with airsacculitis were standardized, associated with the presence of Enterobacteriaceae isolated from these organs. A total of 110 samples of air sacs from male turkeys with airsacculitis were collected and analyzed. During the slaughtering process, the sample collection was done using swabs and submitted to three storage methods (immediate, frozen, or pre incubated after freezing) for further comparison of their isolated efficiency. The bacterial genera of the family Enterobacteriaceae were identified biochemical series EPM, MILi and Simmons citrate. Bacterial growth occurred in 43.64% of samples. In this study, four patterns of aerossaculitis lesions were identified according to the pathological characteristics of air sacs. The frequencies of the Enterobacteriaceae isolated identified in the samples were: Escherichia coli, Citrobacter, Proteus, Edwardsiella, Morganell, Kluyvera, Salmonella and Klebsiella. Otherwise, it was observed that the levels already standardized as level three and four showed higher variety of genus. The immediate storage showed higher percentage of positivity at 41.82%, however, the pre incubated after freezing showed more efficiency in relation to the quantity of colonies.(AU)
Asunto(s)
Animales , Pavos , Sacos Aéreos/microbiología , Enterobacteriaceae/aislamiento & purificación , Infecciones por Enterobacteriaceae/veterinaria , Proteus , Salmonella , Citrobacter , Edwardsiella , Morganella , Kluyvera , Escherichia coli , KlebsiellaRESUMEN
ANTECEDENTES: En el semen, algunos microorganismos pueden encontrar las condiciones óptimas para sobrevivir, ocasionando daños a los espermatozoides y desencadenando procesos de infertilidad o infecciones del tracto reproductivo. Entender el papel de los microorganismos aislados en el semen, contribuye a mejorar el diagnóstico de casos de infertilidad donde la única causa aparente son los procesos infecciosos. OBJETIVO: Describir y correlacionar los parámetros seminales y el crecimiento bacteriano del eyaculado. MÉTODOS: Identificación de los microorganismos aislados en 43 espermocultivos-clínicos y 28 espermocultivos-investigación. Se realizó conteo de las unidades formadoras de colonia a los espermocultivos-investigación y análisis de las características espermáticas. Resultados: Se obtuvo crecimiento bacteriano en 14 (32,6%) de los espermocultivos-clínicos y 15 (53,6%) de los espermocultivos-investigación. Los microorganismos aislados fueron Enterococcus faecalis, Escherichia coli, Morganella morganii, Staphylococcus spp coagulasa negativo, Klebsiella pneumoniae y microbiota mixta. En este estudio se observó abundante crecimiento de cocos aerobios. Finalmente, no se encontró asociación entre la disminución en la calidad de los parámetros seminales y los microorganismos. CONCLUSIONES: La presencia de bacterias en el semen no afecta la calidad seminal.
BACKKGROUND: Microorganisms can find the optimal conditions for survival in semen, causing damage to the spermatozoa and triggering processes of infertility or reproductive tract infections. Therefore, understanding the role of the microorganisms present in semen can help to improve the diagnosis of infertility cases where the only apparent cause is infectious processes. OBJECTIVE: To describe and correlate semen parameters and bacterial growth in ejaculate. METHODS: Identification of microorganisms isolated in 43 clinical spermocultures and 28 research spermocultures. We assessed colony-forming unit counts and sperm characteristics of research spermocultures. In addition, semen parameters were evaluated in each ejaculate. RESULTS: Bacterial growth was obtained in 14 (32.6%) of the 43 clinical spermocultures and 15 (53.6%) of the 28 research spermocultures. The isolated microorganisms were Enterococcus faecalis, Escherichia coli, Morganella morganii, Staphylococcus coagulase negative, Klebsiella pneumoniae and mixed microbiota. Finally, in this study a large growth of aerobic cocci was observed. We did not find association between the decline in the quality of semen parameters and microorganisms. CONCLUSION: The presence of bacteria in semen does not affect semen quality.
Asunto(s)
Humanos , Masculino , Semen/microbiología , Bacterias/aislamiento & purificación , Espermatozoides/microbiología , Bacterias/crecimiento & desarrollo , Recuento de Colonia Microbiana , Enterococcus faecalis/aislamiento & purificación , Morganella/aislamiento & purificación , Eyaculación , Escherichia coli/aislamiento & purificación , Análisis de Semen , Infecciones del Sistema Genital , Microbiota , Infertilidad Masculina , Klebsiella pneumoniaeRESUMEN
El uraco es un remanente embriológico de la alantoides que puede dar lugar a diferentes anomalías, entre las que destaca el quiste de uraco. Se presenta el caso de un varón de cuatro años que consulta por dolor abdominal hipogástrico, fiebre y disuria. La tira reactiva de orina es normal; se realiza una ecografía abdominal que identifica en la región umbilical, inmediatamente por debajo de la pared abdominal y en dudosa comunicación con la vejiga, una imagen tubular lobulada que podría tratarse de un quiste de uraco complicado. Ingresa en el hospital para tratamiento antibiótico intravenoso y en un segundo tiempo se realiza la exéresis quirúrgica de la estructura anómala. El uraco es un remanente embriológico de la alantoides que se convierte en un cordón fibromuscular que se extiende desde la cúpula vesical hasta el ombligo. Si no hay una involución completa del uraco al nacer, puede dar lugar a diferentes anomalías, de las que el quiste uracal representa el 30%. Los quistes uracales suelen ser asintomáticos hasta que debutan en forma de complicaciones, siendo la infección la más frecuente. Para el diagnóstico es útil la ecografía. El tratamiento es antibiótico y el drenaje, y en un segundo tiempo la cirugía. Conviene considerar esta patología en el diagnóstico diferencial del niño con dolor abdominal y sintomatología miccional (AU)
Ultrasound has been considered an additional test to be carried out by image specialists. Since its inception, some specialists like obstetricians or cardiologists have used with great results. Now, the general practitioners and other specialties are approaching this technique that is quick, safe, accessible, inexpensive, and above all allows you to complete real-time exploration of the patient. In many countries and societies the non- radiology specialist physicians are beginning to perform ultrasounds on a daily basis and more and more studies show its usefulness in normal clinical practice (AU)
Asunto(s)
Humanos , Masculino , Preescolar , Quiste del Uraco/complicaciones , Quiste del Uraco/cirugía , Quiste del Uraco , Dolor Abdominal/diagnóstico , Dolor Abdominal/etiología , Ultrasonografía , Morganella/aislamiento & purificación , Diagnóstico Diferencial , Abdomen/patología , Abdomen , Tomografía/métodos , Profilaxis Antibiótica/métodos , Antibacterianos/aislamiento & purificaciónRESUMEN
BACKGROUND: Among the inducible AmpC beta-lactamase-producing members of the family Enterobacteriaceae such as Enterobacter spp., Citrobacter spp., Serratia spp., and Morganella morganii (ECSM), the prevalence of ESBL-producing isolates are increasing. However, there have been only a limited number of studies that have investigated the prevalence for ESBL-production in blood isolates of these organisms. MATERIALS AND METHODS: We performed a prospective observational study to evaluate the prevalence for ESBL production among ECSM blood isolates. All consecutive blood isolates in the Samsung Medical Center were included from Oct 2006 to Mar 2008. Antimicrobial susceptibility test was performed by broth microdilution method. ESBLs were confirmed by double-disk synergy test and ESBL phenotypes were determined by PCR. RESULTS: The 124 isolates (94 Enterobacter spp., 18 Citrobacter spp., 8 Serratia spp. and 4 Morganella spp.) were investigated. Among 124 ESCM isolates, 30 isolates (24.2%) showed ESBL-producing activity. Derepressed or partially derepressed AmpC mutants and derepressed AmpC mutants with ESBL production accounted for 36.3% (45/124) and 16.9% (21/124), respectively. Of ESBL producers, the most prevalent ESBL was SHV-12 (5/24, 20.8%). CONCLUSIONS: The prevalence of ESBL-producing isolates is high in Enterobacter spp., Serratia marcescens and Citrobacter spp. clinical isolates. It suggested that routine screening test for ESBLs among Enterobacteriacae blood isolates with inducible AmpC beta-lactamase should be needed.
Asunto(s)
Humanos , Proteínas Bacterianas , beta-Lactamasas , Citrobacter , Enterobacter , Enterobacteriaceae , Tamizaje Masivo , Morganella , Morganella morganii , Fenotipo , Reacción en Cadena de la Polimerasa , Prevalencia , Estudios Prospectivos , Serratia , Serratia marcescensRESUMEN
PURPOSE: The main objectives of this work were to characterize the mechanism of resistance to imipenem of Morganella morganii KU158 isolated in Busan, Korea and to analyze the structure of the integron, which carries the resistance gene that confers resistance to imipenem. MATERIALS AND METHODS: Antimicrobial susceptibilities of M. morganii KU158 were tested by using the disk diffusion method. The modified Hodge and EDTA-disk synergy tests were performed for the screening of metallo-beta-lactamase-producing isolates. blaIMP and blaVIM genes were detected using the polymerase chain reaction (PCR) amplification. To detect the presence of the integron, the PCR method was used. The PCR product was cloned through the use of primers, 5'CS-F and 3'CS-R, and it was used to determine the sequence of the integron through the dideoxy-mediated chain termination method. RESULTS: M. morganii KU158 was intermediately resistant to imipenem and showed a positive result for the modified Hodge and EDTA-disk synergy tests, which suggest the production of metallo-beta-lactamase, and also was positive in the PCR result for the detection of blaVIM gene. The genotype of the PCR product from the blaVIM gene was blaVIM-2. Sequencing of the 5,031 bp-cloned fragment revealed the structure of the class I integron, such as the 5'-CS element containing an Intl1 integrase gene with its own promoter region, the attI1 recombination site, and the 3'-CS element containing qacE1. The integron contained insert gene cassettes blaVIM-2, aac(6')-Ib, aadA1, "orfII", and "orfIII". The blaVIM-2 gene was located immediately downstream of the aac(6')-Ib gene. CONCLUSIONS: M. morganii KU158 acquired the resistance to imipenem through the production of metallo-beta-lactamase VIM-2. The gradual increase in the number of VIM-2-producing bacterial species may indicate the highly mobile nature of the blaVIM-2 cassette. The spread of blaVIM-2 could compromise the future usefulness of carbapenem in treating gram-negative bacilli infections.
Asunto(s)
beta-Lactamasas , Células Clonales , Difusión , Genotipo , Imipenem , Integrasas , Integrones , Corea (Geográfico) , Tamizaje Masivo , Morganella morganii , Morganella , Reacción en Cadena de la Polimerasa , Regiones Promotoras Genéticas , Recombinación GenéticaRESUMEN
BACKGROUND: In clinical microbiology the accurate and rapid identification of members of the family Enterobacteriaceae is essential for diagnostic and therapeutic purposes and for epidemiologic studies. Accuracy of identification system depends mainly on data base such as positive rate of biochemical reactions, relative frequency of occurrence of biotype, and isolation frequency of microorganisms. The purpose of this study was to analyze the isolation rate and biotype frequency of the family Enterobacteriaceae isolated from tertiary care hospital in Korea. METHODS: Isolation frequency of the family Enterobacteriaceae isolated from clinical specimens during the period of January 1998 to June 1998 were analyzed. And biochemical phenotypes of 2,022 isolates tested by 10 tube system consisting of 14 conventional biochemical tests were also analyzed. RESULTS: Isolation rate of the family Enterobacteriaceae to the genus level in order of decreasing frequency were Escherichia (37.0%), Serratia (15.9%), Klebsiella (14.9%), Enterobacter (11.1%), Providencia (8.1%), Citrobacter (2.8%), Proteus (2.5%), Morganella (2.4%), Salmonella (2.4%), and Cedecea (0.7%). Among the genus of the family Enterobacteriaceae, Budvicia, Edwardsiella, Ewingella, Hafnia, Kluyvera, Leminorella, Moellerella, Shigella, Tatumella, Xenorhabdus, Yersinia, and Yokenella were not isolated. The number of species and genus of the family Enterobacteriaceae by this study were 48 and 12, respectively. Over 95% of all clinical isolates belonged to only 25 species. CONCLUSIONS: Although these data about frequency of relative isolation rate and biotype patterns of the family Enterobacteriaceae is inadequate according to species and genus, yet these data will be utilized for the application and development of identification method of the family Enterobacteriaceae.
Asunto(s)
Humanos , Citrobacter , Edwardsiella , Enterobacter , Enterobacteriaceae , Escherichia , Hafnia , Klebsiella , Kluyvera , Corea (Geográfico) , Morganella , Fenotipo , Proteus , Providencia , Salmonella , Serratia , Shigella , Atención Terciaria de Salud , Xenorhabdus , YersiniaRESUMEN
Morganella morganii, a gram, negative rod is often regarded as an opportunistic, secondary invader rather than a primary pathogen on the skin. It has been isolated from blood, sputa, and pus from patients with respiratory tract and wound infections or with bacteremia. A 2-year-old boy presented with erythematous ulcerative lesions on the cheeks and left knee which had a tendency to superficial scarring. The organism isolated from the ulcer displayed a biochemical char acteristics typical of Morganella morganii. The lesions responded well to systemic antibiotic therapy with amikacin and carbenicillin, which were recognized as effective drugs in in vitro sensitivity testing.
Asunto(s)
Preescolar , Humanos , Masculino , Amicacina , Bacteriemia , Carbenicilina , Mejilla , Cicatriz , Rodilla , Morganella morganii , Morganella , Sistema Respiratorio , Úlcera Cutánea , Piel , Supuración , Trucha , Úlcera , Infección de HeridasRESUMEN
Urinary tract infections constitute a large clinical problems that particularly affect catheter indwelling patients, causing morbidity and mortality. To investigate 1) the rate of infection by duration of catheter indwelling in patients of several kinds of disease, 2) the kinds of colonized bacteria and the similarity or difference of the bacterial species cultured in the urine and catheter of same patient, and 3) the comparison of sensitivity to antibiotics of cultured bacteria of both material, bacterial culture and antibiotic sensitivity test were done from urine and proximal tip of catheters in 31 catheter indwelling patients who had been administered, sometimes intermittently, various antibiotics. The rate of bacterial infection increased markedly with the lengthening of catheter indwelling period in urine and catheter cultures, 22.2% and 33.3% at 1 week, both 50% at 2-3 weeks, 78.6% and 85.7% at 4 weeks respectively The results of bacterial culture from both material were same in 27 (87.1%) patients. The gram negative bacteria composed of 41 (89.1%) species in cultured bacteria. The three frequent species were 16 (34.8%) Escherichia coli, 9 (19.6%) Klebsiella pneumonia, and 6 (13.0%) Morganella morgagni. The overall sensitivity of urine cultured bacteria to tested antibiotics showed minor difference from that of catheter, susceptible in 70.4%, and 73.8%, resistant in 28. 6%, and 24.6%, respectively. Almost all of the patients indwelling catheter longer than 4 weeks had bacterial infection or colonization in urine and proximal catheter-tip in spite of preventive administration of antibiotics. The urine culture only may be enough instead of culturing both the urine and proximal catheter-tip in long-term catheterized patients. Routine antibacterial drug administration should be taken into consideration not to be overused in long-term catheter indwelling patients.
Asunto(s)
Humanos , Antibacterianos , Bacterias , Infecciones Bacterianas , Catéteres , Catéteres de Permanencia , Colon , Escherichia coli , Bacterias Gramnegativas , Klebsiella , Morganella , Mortalidad , Neumonía , Infecciones UrinariasRESUMEN
Endoscopic biliary stents provide effective palliation of malignant obstructive jaundice in patients who are not surgical candidates. Unfortunately the stents in current use have a tendency to block. The clogging phenomenon also severely restricts the value of stents in patients with benign strictures. We studied the mechanism of the occlusion of biliary stents to find ways to prevent it. We have examined 17 blocked stents by electron microscopy(EM), infrared absorption spectrophotometry, and bacteriological cultures. The mean time to stent clogging with 10 french stents was 131 days, and with 12 French stents was 143 days. The differece between the clogging time of the two stents was statistically not sigificant. Scanning EM showed that the internal surfaces of the stent were covered with bacteria embedded in a condensed fibrillar intercellular matrix. The bacteris form a surrounding fibrillar extracellular product which anchors them to the stent. Inorganic crystals were rarely seen, because they presumable dissolved during the fixing for EM. These EM findings are typical of a biofilm. As major components of the occluding material calcium bilirubinate was identified in 15 stents by infrared absorption spectrophotometry. 7 different microorgainsms were isolated from the 17 blocked biliary stents. 6 of the isolates were gram-negative, and 1 was gram-positive. The most frequently isolated genus was Escherichia, which was found in 8 stents, followed by proteus, Pseudomonas, and Morganella, which was found in 2 stents respectvely. We propose that stent colgging is initiated by bacterial adhesion and growth of a biofilm. The bacteria then deconjugate bilirubin in bile and the lumen is progressively occluded by deposition of calcium bilirubinate and further biofilm formation.