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PubMedDate not supplied

Biosorption of lead, cadmium, and zinc by Citrobacter strain MCM B-181: characterization studies.

The biosorption process for removal of lead, cadmium, and zinc by Citrobacter strain MCM B-181, a laboratory isolate, was characterized. Effects of environmental factors and growth conditions on metal uptake capacity were studied. Pretreatment of biomass with chemical agents increased cadmium sorption efficiency; however, there was no significant enhancement in lead and zinc sorption capacity. Metal sorption by Citrobacter strain MCM B-181 was found to be influenced by the pH of the solution, initial metal concentration, biomass concentration, and type of growth medium. The metal sorption process was not affected by the age of the culture or change in temperature. Equilibrium metal sorption was found to fit the Langmuir adsorption model. Kinetic studies showed that metal uptake by Citrobacter strain MCM B-181 was a fast process, requiring <20 min to achieve >90% adsorption efficiency. The presence of cations reduced lead, zinc, and cadmium sorption to the extent of 11. 8%, 84.3%, and 33.4%, respectively. When biomass was exposed to multimetal solutions, metals were adsorbed in the order Co2+ < Ni2+ < Cd2+ < Cu2+ < Zn2+ < Pb2+. Among various anions tested, only phosphate and citrate were found to hamper metal sorption capacity of cells. Biosorbent beads prepared by immobilizing the Citrobacter biomass in polysulfone matrix exhibited high metal loading capacities. A new mathematical model used for batch kinetic studies was found to be highly useful in prediction of experimentally obtained metal concentration profiles as a function of time. Metal desorption studies indicated that Citrobacter beads could, in principle, be regenerated and reused in adsorption-desorption cycles. In an expanded scale trial, biosorbent beads were found to be useful in removal/recovery of metals such as lead from industrial wastewaters.

Adsorption↗
PubMed2003

Citrobacter rodentium translocated intimin receptor (Tir) is an essential virulence factor needed for actin condensation, intestinal colonization and colonic hyperplasia in mice.

Citrobacter rodentium infection of mice serves as a relevant small animal model to study enterohaemorrhagic Escherichia coli (EHEC) and enteropathogenic E. coli (EPEC) infections in man. Enteropathogenic E. coli and EHEC translocate Tir into the host cytoplasmic membrane, where it serves as the receptor for the bacterial adhesin intimin and plays a central role in actin condensation beneath the adherent bacterium. In this report, we examined the function of C. rodentium Tir both in vitro and in vivo. Similar to EPEC, C. rodentium Tir is tyrosine phosphorylated and is essential for actin condensation. Citrobacter Tir and EPEC Tir are functionally interchangeable and both require tyrosine phosphorylation to mediate actin rearrangements. In contrast, Citrobacter Tir supports actin nucleation in EHEC independent of tyrosine phosphorylation, while EHEC Tir cannot replace Citrobacter Tir for this function. This indicates that C. rodentium and EPEC use an actin nucleating mechanism different from EHEC. We also found that Tir is expressed and translocated into mouse enterocytes in vivo by C. rodentium during infections. This represents the first direct demonstration of a type III effector translocated in vivo into a natural host by any pathogen. In addition, we showed that Tir, but not its tyrosine phosphorylation, is essential for C. rodentium to colonize the large bowel and induce attaching/effacing (A/E) lesions and colonic hyperplasia in mice, and that both EPEC Tir and EHEC Tir can substitute for Citrobacter Tir for these activities in vivo. These results thus demonstrate that Tir is an essential virulence factor in this infection model. The data also show that the function of Tir tyrosine phosphorylation and its subsequent actin nucleating activity are not essential for C. rodentium colonization of the mouse gut nor for inducing A/E lesions and colonic hyperplasia, thereby uncoupling colonization and disease from actin condensation for this A/E pathogen.

Actins↗
PubMed1997

Vertical transmission of a Citrobacter infection.

Citrobacter species have rarely been described as-etiological factors of intraamniotic infections. Citrobacter is not a normal inhabitant of the female genital tract. Vertical transmission of Citrobacter from mother to fetus has rarely been reported. A 21-year-old primigravida presented to labor and delivery at 40 6/7 weeks' gestation complaining of ruptured membranes, painful uterine contractions, and fever. An intraamniotic infection was diagnosed and antibiotics begun. She was subsequently delivered of a live male infant. Mother and infant had positive cultures for Citrobacter and overwhelming sepsis. Citrobacter species are rarely described as etiological factors of intraamniotic infections, and vertical transmission has rarely been reported. This pathogen should be considered in cases of chorioamnionitis or maternal sepsis as overwhelming maternal and fetal infection are possible sequelae.

Adult↗
PubMed1993

Unusual microtubule-dependent endocytosis mechanisms triggered by Campylobacter jejuni and Citrobacter freundii.

Bacterial invasion of six different human epithelial cell lines showed that some strains of the intestinal pathogen Campylobacter jejuni invaded intestinal cell lines at a level 10(2)-10(4) times higher than reported previously for other Campylobacter strains. Separately, urinary tract isolates of Citrobacter freundii triggered a high-efficiency invasion of bladder cells. Use of multiple inhibitors with known effects on eukaryotic cell structures/processes allowed us to define in these genetically distinct bacterial genera unusual bacterial invasion mechanisms that uniquely require microtubules but not microfilaments. Campylobacter jejuni strain 81-176 uptake into 407 intestinal cells and Citrobacter entry into T24 bladder cells was blocked by microtubule depolymerization and inhibitors of coated-pit formation but not by microfilament depolymerization. Inhibitors of endosome acidification had no significant impact on intracellular survival of Campylobacter jejuni or Citrobacter freundii, but monensin markedly reduced Citrobacter uptake. Epithelial cell invasion by both of these bacterial genera was dependent upon de novo bacterial protein synthesis but not upon de novo eukaryotic cell protein synthesis. In contrast to the T24 cell line-specific, strict microtubule-dependent uptake, Citrobacter entry into other cell lines was inhibited by both microtubule- and microfilament-depolymerization, suggesting that these bacteria encode two separate pathways for uptake (i, microtubule-dependent; ii, microfilament-dependent) that are cell line-specific and are recognized perhaps depending on the presence and abundance of appropriate eukaryotic receptors.

Campylobacter jejuni↗
PubMed1999

The role of Citrobacter in clinical disease of children: review.

Various species of Citrobacter may cause infections in neonates and immunocompromised hosts. Citrobacter koseri (formerly Citrobacter diversus) is best known as the cause of sepsis and meningitis leading to central nervous system (CNS) abscesses in neonates and young infants. Early onset and late-onset infections occur as for other neonatal bacterial infections. The majority of cases are sporadic, with no clear source of infection. A few have been confirmed to be vertically transmitted, and nosocomial outbreaks have occurred in neonatal care units. The pathophysiology is not well understood, but a surface protein has been identified as a possible virulence factor among strains that cause citrobacter brain abscesses in neonates. Despite improvements in diagnostic imaging techniques, surgery, and antibiotic therapy, approximately one-third of infants with abscesses die, and one-half sustain CNS damage. In this article, the taxonomy, epidemiology, pathogenesis, diagnosis, treatment, and outcome of citrobacter disease in children are reviewed.

Child↗
PubMed1977

Antimicrobial susceptibility patterns (antibiograms) as an aid in differentiating Citrobacter species.

The hydrogen sulfide-negative Citrobacter group represents a taxonomic problem. Various investigators have proposed such designations as Padlewskia, Levinea, atypical Enterobacter cloacae, H2S-negative variants of Citrobacter, Citrobacter koseri and Citrobacter diversus. This problem has been investigated with emphasis on antibiograms as a means of discrimination. Clinical isolates fitting the designation Citrobacter were studied and, using the criteria of Ewing and Davis, separated into two groups: C. diversus (40 strains) or C. freundii (25 strains). Susceptibilities to ampicillin, carbenicillin, cefazolin, cephaloridine and cephalothin were determined by the agar-dilution method. C. diversus strains were resistant to 8 mug/ml ampicillin (97.5%) and 32 mug/ml carbenicillin (87.5%), and were susceptible to 8 mug/ml cephalosporins (greater than or equal to 90%). C. freundii strains were moderately susceptible to 8 mug/ml ampicillin (25%) and susceptible to 8 mug/ml carbenicillin (92%), and were resistant to 8 mug/ml cephalosporin (greater than or equal 92%). Using these data one can separate C. diversus from C. freundii with 90% accuracy.

Ampicillin↗
PubMed1977

Distinctive electrophoretic patterns of Esterases from Levinea malonatica, Levinea amalonatica and Citrobacter.

Esterases of 42 strains of Levinea malonatica, Levinea amalonatica and Citrobacter were analysed by horizontal slab electrophoresis in polyacrylamide-agarosegel using several synthetic substrates. On the basis of esterase zymograms a distinctive pattern was established for each of the three species. Levinea malonatica was characterized by two major bands: one hydrolysing acetate esters but not butyrate esters; and the other hydrolysing alpha-naphthyl acetate and reacting weakly with alpha-naphthyl butyrate and beta-naphthyl acetate. Levinea amalonatica showed one prominent band that hydrolysed alpha-naphthyl esters and reacter weakly with beta-naphthyl esters. Citrobacter strains showed one major band that hydrolysed alpha-naphthyl esters and appeared slightly more towards beta-naphthyl esters than that of L. amalonatica. Considerable variations in electrophoretic mobility were observed among Citrobacter strains. Levinea amalonatica was less variable. In addition, one minor anodal band reacting with beta-naphthyl acetate was observed in both L. malonatica and Citrobacter. The relative molecular sizes of the major esterase bands were determined by disc electrophoresis with gels of different acrylamide concentrations. The molecular size of the major band of Citrobacter appeared to be smaller than that of the corresponding esterase band of L. amalonatica.

Citrobacter↗
PubMed2006

Characterization of the chromosomal class A beta-lactamase CKO from Citrobacter koseri.

The gene bla(CKO) encoding the chromosomal class A beta-lactamase of Citrobacter koseri was cloned and sequenced. CKO was found to display only 41% identity with SED-1 from Citrobacter sedlakii and 36% with CdiA from Citrobacter amalonaticus (formerly Citrobacter diversus). No transcriptional regulator was found upstream from bla(CKO). Silent and missense mutations were detected in four bla(CKO) genes amplified from different C. koseri clinical isolates, but the CKO variants displayed identical biochemical behaviours. A bla(CKO)-specific polymerase chain reaction confirmed that bla(CKO) is present only in C. koseri and therefore represents an interesting tool with which to differentiate C. koseri from the other Citrobacter spp.

Amino Acid Substitution↗
PubMed1995

Genetic and biochemical characterization of Citrobacter rodentium sp. nov.

An unusual bacterial pathogen of laboratory mice has been previously classified as an atypical biotype of Citrobacter freundii. Designated C. freundii biotype 4280, this bacterium is the etiologic agent of transmissible murine clonic hyperplasia. An eaeA gene has been shown to be present in this organism and to be necessary for virulence in laboratory mice. However, other biotypes of C. freundii lack DNA homology with the eaeA gene. Because of the recent reclassification in which five named species and three unnamed species, all previously considered C. freundii, were described, we determined the taxonomic status of C. freundii biotype 4280. With a battery of biochemical tests and DNA relatedness studies, three isolates of C. freundii biotype 4280 were shown to be members of an unnamed Citrobacter species, designated species 9. In total, six isolates of Citrobacter species 9, but none of the type strains of the other eight named species or of the two remaining unnamed species of Citrobacter, were shown to possess DNA homology with both the eaeA and the eaeB genes. Species 9 was named Citrobacter rodentium sp. nov.

Animals↗
PubMed1975

[Frequency of detecting bacteria of the genera Citrobacter and Hafnia in different contingents of examined adults].

A study of the incidence of bacteria of the Citrobacter and Hafnia genus in adults permitted to establish a greater occurrence of the mentioned microbes in the patients with various acute intestinal diseases in comparison with the healthy ones. Bacteria of the Citrobacter and Hafnia genus were revealed in the patients with acute intestinal diseases of obscure etiology, which often were diagnosed as gastroenteritis, enteritis, etc. Bacteria of the Citrobacter and Hafnia genus were revealed in the dysentery patients. Results of studies carried out among various healthy groups of the population indicated no significant differences in respect to the carrier state of the Citrobacter and Hafnia bacteria both within each of the groups of the persons examined and between them. Further studies directed to the investigation of the etiological role of bacteria of the Citrobacter and Hafnia genus in the pathology of enteric disturbances are necessary.

Acute Disease↗
PubMed1978

The characteristic and clinical importance of bacteria of the genus Citrobacter isolated from patients with acute intestinal infections on the territory of Volgograd.

A total of 309 Citrobacter strains isolated from patients with acute intestinal infections of obscure aetiology and from healthy subjects were investigated. Species specificity of the bacterial cultures was determined by biochemical tests recommended by the International Enterobacteriaceae Subcommittee. Citrobacter strains were titrated serologically in the reaction of agglutination on glass with a living culture and adsorbed 0-antisera. Eighteen serological 0 groups were identified; 0 groups 3, 9, 23, 1 and 8 were found most frequently. Citrobacter was isolated more frequently from patients with acute intestinal infections than from healthy subjects. Seasonal circulation of Citrobacter strains in spring and summer was established. The number of culture findings of Citrobacter in the patients increased against the background of reduction in the number of cases of bacteriologically confirmed dysentery.

Acute Disease↗
PubMed1984

Intra-abdominal Citrobacter infections: association with biliary or upper gastrointestinal source.

The clinical records of 46 patients with intra-abdominal and/or bacteremic infections caused by Citrobacter organisms were reviewed to determine whether the isolation of Citrobacter organisms from these sites could be used to determine its portal of entry. The isolation of Citrobacter organisms from intra-abdominal or pleural fluid cultures was associated with a biliary tract or upper gastrointestinal source in 36 of 41 patients. The biliary tract or small bowel was likewise the portal of entry for 8 to 13 patients with Citrobacter septicemia. Thus, the isolation of these organisms from the blood, pleural space, or abdominal cavity strongly suggests that the upper gastrointestinal (or biliary) tract is the site of significant pathologic disease. Of the antibiotics tested, moxalactam, cefotaxime, and amikacin were most effective against Citrobacter.

Adolescent↗
PubMed1976

Serotyping of strains belonging to the Citrobacter-Levinea group isolated from diagnostic material.

A proposal is presented for the serotyping of Citrobacter-Levinea strains: 9 serotypes for Citrobacter diversus (Levinea malonatica) and 13 serotypes for H2S-negative, indole-positive variants of Citrobacter freundii (Levinea amalonatica), which showed a considerable antigenic diversity. By means of both kinds of antiserum types 80 per cent of the strains (L. malonatica 100 per cent, L. amalonatica 72 per cent) from a series of 106 strains isolated from different diagnostic material were serologically classified. According to results presented in this paper, a direct relationship between biotype and serotype was found among the strains of biotype b for Levinea amalonatica and c for L. malonatica, which were agglutinated by the antisera prepared from biotypes b and c, respectively, only. Serotyping will evidently greatly contribute to a more perfect identification, especially of those strains that are, for various reasons, classified among so called intermediates. The importance of the Citrobacter freundii and C. diversus species in the clinical material is emphasized with a view to their increasing occurrence. Taxonomic and nomenclature questions with regard to Citrobacter-Levinea are discussed in detail.

Animals↗
PubMedDate not supplied

CSF interleukin-6 in neonatal Citrobacter ventriculitis after meningitis.

An infant with neonatal severe Citrobacter koseri (formerly Citrobacter diversus) meningoencephalitis developed necrosis with multicystic regression of both hemispheres. The ventriculitis persisted over months in spite of antibiotic therapy. The treatment succeeded with cefotaxime in a high dose (300 mg/kg/day) without surgical intervention. The infant had been previously treated with cefotaxime (200 mg/kg/day) over 5 weeks. High levels of CSF interleukin-6 (IL-6) permitted to attribute persisting CSF pleocytosis in spite of sterile CSF cultures to chronic infection and not to reminiscence of brain necrosis. This report reveals two main points. On the one hand, the importance of therapy monitoring with IL-6 in CSF for the consequent treatment of Citrobacter meningitis and on the other hand, high-dose cefotaxime (300 mg/kg/day) treatment of Citrobacter ventriculitis, which succeeded without surgical intervention.

Biomarkers↗
PubMed1999

Use of pyrrolidonyl peptidase to distinguish Citrobacter from Salmonella.

In the routine testing of foods for Salmonella, Citrobacter and other members of the Enterobacteriaceae often produce colonies which are almost indistinguishable from Salmonella on commonly used selective agars. Biochemical confirmation of such colonies can be expensive and time-consuming. It has been suggested that the enzyme pyrrolidonyl peptidase (PYRase) could be used as a rapid test to distinguish Citrobacter colonies (PYRase-positive) from Salmonella (PYRase-negative). Pure cultures of Salmonella, Citrobacter and other Enterobacteriaceae were tested for PYRase activity; all strains of Salmonella tested were PYRase-negative, and all Citrobacter tested were PYRase-positive. Inoculated and naturally contaminated food samples were tested for the presence of Salmonella by a standard cultural method. A PYR test was used to test Salmonella-like colonies isolated on selective agar and potentially, eliminate PYR-positive isolates from further biochemical testing. The test was able to screen out 6% of colonies selected from samples inoculated with Salmonella, and 43% of colonies selected from uninoculated samples.

Bacterial Typing Techniques↗
PubMed2003

Citrobacter koseri (diversus) meningitis in an otherwise healthy adolescent.

Citrobacter infection is commonly reported in neonates and immunocompromised patients. Citrobacter koseri (diversus) is an important cause of neonatal meningitis and brain abscess formation. It adults, however, Citrobacter infection with central nervous system involvement is rare, and is usually associated with an underlying disorder. This report describes a 12-y-old previously healthy girl with Citrobacter koseri meningitis. Intravenous treatment with ceftriaxone for 10 d led to complete recovery. Head computed tomography and brainstem-evoked response audiometry were normal. On follow-up, the patient was completely healthy. Previously reported cases of C. koseri meningitis in the adult population were associated with underlying predisposing factors. In this case a normal, healthy adolescent was treated with intravenous ceftriaxone without any of the known neurological complications observed in the neonatal cases.

Ceftriaxone↗
PubMed1996

Bacteremia due to Citrobacter species: significance of primary intraabdominal infection.

From 1982 to 1994, 45 patients (1.22 episodes per 10,000 discharged patients) were treated for citrobacter bacteremia at National Taiwan University Hospital (Taipei). All patients had at least one underlying disease. Citrobacter bacteremia most commonly occurred in patients with malignancies (48.9%) or hepatobiliary stones (22.2%). Intraabdominal tumors comprised the majority (59.1%) of malignancies. Bacteremia commonly originated from sites such as the abdominal cavity (51.1%), urinary tract (20%), and lung (11.1%). Polymicrobial bacteremia was diagnosed in 15 patients (33.3%); for nine (60%) of these patients, the source of the infection was intraabdominal. Prior treatment with a third-generation cephalosporin was significantly associated (P < .01) with the development of multidrug resistance among the isolates. The mortality associated with citrobacter bacteremia was 17.8%. Poor prognostic factors included pneumonia, altered mental status on presentation, hypothermia, oliguria, septic shock, deterioration in mental status, hyperbilirubinemia, azotemia, and thrombocytopenia. Combination therapy, as compared with other regimens, improved the outcome of citrobacter bacteremia.

Adolescent↗
PubMed2003

Sepsis in a renal transplant recipient due to Citrobacter braakii.

Cellulitis is usually caused by organisms such as beta-hemolytic streptococci and Staphylococcus aureus. Citrobacter are gram-negative bacilli that can cause opportunistic infections in immunocompromised hosts. They are rarely implicated in skin or soft tissue infections. The genus Citrobacter has been respeciated according to genetic relatedness. Citrobacter braakii refers to the genomospecies 6 of the Citrobacter freundii complex. There are no detailed studies of infections caused by the newly formed specific genetic species. We report a case of C. braakii infection in a renal transplant patient receiving immunosuppressive therapy. The patient's lower extremity cellulitis did not respond to conventional antibiotic therapy. Blood cultures grew C. braakii. Sensitivity studies and treatment with appropriate antibiotics resulted in prompt recovery. Immunosuppressive therapy in renal transplant recipients predisposes to infection by unusual pathogens, and this should be suspected when lack of a clinical response to conventional antibiotics is observed. We believe this is the first reported case of C. braakii cellulitis and bacteremia in a renal transplant recipient.

Anti-Bacterial Agents↗