Citrobacter Diversus Research Articles

A comparative study of the BBL crystal enteric/nonfermenter identification system and the biomerieux API20E and API20NE identification systems after overnight incubation

The BBL Crystal Enteric/Nonfermenter (Crystal, Becton Dickinson Microbiology Systems) is a new multi-test identification system for Gram negative rods requiring no oil overlay or addition of reagents. One hundred and three selected Gram negative rod isolates from routine clinical specimens were tested in parallel using the appropriate API20E or API20NE (BioMerieux) reading after overnight incubation. The isolates included in the study, and the number tested, were as follows: Acinetobacter sp, 8; Aeromonas hydrophila, 1; Citrobacter diversus, 1; Citrobacter freundii, 1; Escherichia coli, 13; Enterobacter aerogenes, 10; Enterobacter agglomerans, 2; Enterobacter cloacae, 6; Klebsiella oxytoca, 6; Klebsiella pneumoniae, 12; Morganella morganii, 2; Proteus mirabilis, 6; Pseudomonas aeruginosa, 21; Salmonella sp, 2; Salmonella typhi, 1; Serratia marcescens, 1; Shigella sonnei, 2; Shigella sp, 2; Vibrio metschnikovii, 1; Xanthomonas maltophilia, 3; and, Yersinia enterocolitica, 2. The API20E and API20NE systems combined identified 74.8% (77/103) and the Crystal 97.1% (100/103) of isolates. Twenty six isolates required repeat and/or additional tests for correct identification with the API systems compared to 3 with the Crystal. Crystal is more convenient than API for routine clinical use because it requires fewer repeat and/or extra tests, and is easier and less time consuming to use.

Localized Genital Kaposi Sarcoma

Localized Genital Kaposi Sarcoma

Inhibition of Campylobacter jejuni colonization in chicks by defined competitive exclusion bacteria

Campylobacter enteritis in humans has been linked to consumption of chicken. Reducing Campylobacter jejuni colonization in chickens can potentially reduce Campylobacter infections in humans. In this study, the reduction of C. jejuni colonization in chicks by oral administration of defined competitive exclusion (CE) cultures, 2.5% dietary carbohydrates, or CE cultures and carbohydrates was examined. Prevention, elimination, or direct challenge of Campylobacter infection was simulated by administering treatments before, after, or at the same time as that of the Campylobacter inoculation. Additionally, the effect of maintaining high levels of protective bacteria was evaluated by administering CE cultures on days 1 and 4 (booster treatment). All treatments reduced C. jejuni colonization. Protection by aerobically grown CE cultures was not statistically different from that by anaerobically grown CE cultures. A combination of Citrobacter diversus 22, Klebsiella pneumoniae 23, and Escherichia coli 25 (CE 3) was the most effective CE treatment. Maintaining high numbers of CE isolates by administering CE boosters did not increase protection. The greatest reduction of Campylobacter colonization was observed in schemes to prevent or eliminate C. jejuni infection. C. jejuni was not detected in the ceca of birds receiving the prevention treatment, CE 3 with mannose, representing a 62% reduction in the colonization rate. The protection factor (PF), a value combining the colonization rate and the level of infection, for CE 3 with mannose was high (> 13.2). Fructo-oligosaccharides alone strongly prevented Campylobacter colonization. Only 8% of the chicks in this group were colonized, with a PF of > 14.3.(ABSTRACT TRUNCATED AT 250 WORDS)

A new class of proteins regulating gene expression in enterobacteria.

YmoA and Hha are highly similar bacterial proteins downregulating gene expression in Yersinia enterocolitica and Escherichia coli, respectively. The phenotype of ymoA mutants evokes that of mutants affected in some histone-like proteins. This paper describes complementation of a ymoA mutation in Y. enterocolitica by the hha gene from E. coli. We show that YmoA and Hha are not only very similar proteins but that they are functionally interchangeable. Genetic experiments indicate that Hha can also stimulate transposition events in vivo. By Southern blot analysis we detected hha-homologous genes at least in Citrobacter diversus, Shigella flexneri, Shigella dysenteriae, Klebsiella pneumoniae and Salmonella typhimurium. We suggest that both YmoA and Hha belong to a new family of proteins downregulating gene expression in different enterobacteria.

Recurring Ventriculitis Due to Citrobacter diversus: Clinical and Bacteriologic Analysis

Neonatal meningitis due to Citrobacter diversus is usually accompanied by the development of brain abscesses and tends to have high rates of morbidity and mortality. We report a case of a newborn with C. diversus meningitis and brain abscesses who relapsed after initial antibiotic therapy and from whom C. diversus was recovered from cerebrospinal fluid 4 years later during a neurosurgical procedure. Genetic differences in the early and late isolates were discovered, and explanations for this phenomenon are suggested. Possible mechanisms for prolonged persistence in the central nervous system are explored. This unusual case and the analysis of the organisms illustrate the unique features of C. diversus as a pathogen and underscore the need for developing optimal therapeutic strategies.

Whole-cell repetitive element sequence-based polymerase chain reaction allows rapid assessment of clonal relationships of bacterial isolates

Repetitive element sequence-based polymerase chain reaction (rep-PCR) enables the generation of DNA fingerprints which discriminate bacterial species and strains. We describe the application of whole-cell methods which allow specimens from broth cultures or colonies from agar plates to be utilized directly in the PCR mixture. The rep-PCR-generated DNA fingerprints obtained with whole-cell samples match results obtained with genomic DNA templates. Examples with different gram-negative bacteria (e.g., Citrobacter diversus, Escherichia coli, and Pseudomonas aeruginosa) and gram-positive bacteria (e.g., Staphylococcus aureus and Streptococcus pneumoniae) are demonstrated. Rapid specimen preparation methods enable rep-PCR-based fingerprinting to be completed in several hours and, therefore, allows the timely analysis of epidemiological relationships.

Peritonsillar Abscess, Retropharyngeal Abscess, Mediastinitis, and Nonclostridial Anaerobic Myonecrosis: A Case Report

Peritonsillar abscess is a potentially life-threatening complication of acute tonsillitis. On occasion, peritonsillar abscess can extend to neck spaces and/or to the mediastinum. We describe a case of a patient with a peritonsillar abscess that extended to the neck, producing bilateral retropharyngeal abscesses and myonecrosis of the strap muscles. Culture of a specimen of the necrotic muscle yielded Prevotella intermedia, Prevotella buccae, Lactobacillus catenaforme, another Lactobacillus species, Peptostreptococcus anaerobius, and some nonanaerobes. Culture of the peritonsillar abscess yielded P. intermedia and P. buccae plus P. anaerobius, Peptostreptococcus asaccharolyticus, Bifidobacterium dentium, viridans and group F streptococci, and Citrobacter diversus. Culture of the retropharyngeal abscess yielded Fusobacterium nucleatum and Actinomyces odontolyticus in addition to most of the aforementioned organisms. The patient underwent repeated drainage and debridement procedures and was treated with various antimicrobial agents and ultimately recovered. This case highlights the polymicrobial nature of peritonsillar abscess and the serious complications that this infection may lead to.

-Lactamase of Lysobacter enzymogenes: cloning, characterization and expression of the gene and comparison of the enzyme to other lactamases

The gene for the periplasmic beta-lactamase of Lysobacter enzymogenes was isolated as part of a 1017 bp EcoRI fragment and the nucleotide sequence of the gene was determined. It has a G+C content of 71.5% and encodes a 27 amino acid signal sequence and the mature beta-lactamase of 276 amino acids which has a mass of 29,146 Da. The enzyme appears to be unique to L. enzymogenes but its amino acid sequence shows a high degree of homology with the amino acid sequences of the lactamase from Citrobacter diversus and other Class A beta-lactamases. The beta-lactamase gene of L. enzymogenes was expressed in Escherichia coli using pUC118 as the vector. The production of active beta-lactamase was highest after the active growth phase of the expression host and reached levels which were about three times higher than those obtained with L. enzymogenes.

Phylogenetic Tree and Sequence Similarity of β-Lactamases

β-Lactamases are the main cause of β-lactam resistance in many pathogenic bacteria. These enzymes can be detected in a variety of pathogenic as well as non-pathogenic bacteria. The cyanobacteria are also known to produce a β-lactamase. Recently, the amino acid sequences and the three-dimensional structures of some of these β-lactamases have been clarified. On the basis of the amino acid sequences of 47 β-lactamases and the computer-aided analysis, a phylogenetic tree is proposed in this paper. According to the tree, β-lactamases are classified into six groups. Group 1 β-lactamases are mainly composed of plasmid-mediated enzymes from gram-negative bacteria. However, chromosome-derived β-lactamases from Klebsiella pneumoniae and Rhodopseudomonas capsulata take part in this group. Group 2 enzymes consist of a part of the chromosome-encoded β-lactamases from Streptomyces, and chromosome-mediated enzymes from Yersinia enterocolitica, Citrobacter diversus, and Klebsiella oxytoca. Chromosome-encoded β-lactamases from gram-negative bacteria form group 3. Group 4 is composed of metalloenzymes, whereas group 5 consists of OXA type β-lactamases. Chromosome-encoded β-lactamases from gram-positive bacteria form group 6. Comparison of the amino acid sequences among these groups confirmed the phylogenetic tree and the classification: the β-lactamases in each group have its particular conserved amino acid sequences. In addition, the tree provides more detailed classification and time-scale mutual relationships and predicts new types of β-lactamases that may be found. Furthermore, the classification deduced from the tree is generally in accord with the one based on the amino acid sequences reported previously. However, the class A β-lactamases are clearly divided into three groups: groups 1, 2, and 6. RDF2 analysis shows that some combinations between β-lactamases and β-lactam-interacting proteins as well as eukaryotic proteins have a low but significant evolutionary relatedness.

Opinion 67: Rejection of the Name Citrobacter diversus Werkman and Gillen 1932: Judicial Commission of the International Committee on Systematic Bacteriology

The name Citrobacter diversus has been rejected as a nomen dubium because it was used incorrectly by Ewing and Davis in 1972 as the name for a new species that differed in at least eight charamcteristics from the organism described by Werkman and Gillen in 1932 as Citrobacter diversum [sic].

Gram-negative enteric bacillary meningitis: A twenty-one-year experience

We reviewed our experience with gram-negative enteric bacillary meningitis in neonates and infants from 1969 through 1989. Ninety-eight patients were identified. Their ages were from 1 day to 2 years with a median of 10 days. In 25 patients (26%), predisposing factors were identified, the most common of which were neural tube defects and urinary tract anomalies. The causative agents were Escherichia coli (53%), Klebsiella-Enterobacter species (16%), Citrobacter diversus (9%), Salmonella species (9%), Proteus mirabilis (4%), Serratia marcescens (3%), Bacteroides fragilis (3%), and Aeromonas species (2%). At the time of diagnosis, Gram-stained smears of cerebrospinal fluid revealed gram-negative bacilli in 61% of patients. The causative organism was cultured from blood obtained from 55% of patients, and 21% had positive urine culture results. The cerebrospinal fluid leukocyte counts ranged from 0 to 80,600 cells/mm3, and the cerebrospinal fluid/serum glucose concentration ratio was less than 0.5 in 72% of patients. Antimicrobial regimens varied greatly. After initiation of antibiotic therapy, an average of 3 days was needed for eradication of bacteria from cerebrospinal fluid. The case-fatality rate was 17%, and 61% of survivors had long-term sequelae that included seizure disorders, hydrocephalus, physical disability, developmental delay, and hearing loss.

Interaction of Citrobacter diversus strains with HEp-2 epithelial and human umbilical vein endothelial cells.

More than 75% of neonates with Citrobacter diversus meningitis develop brain abscesses. Interaction of C. diversus strains with HEp-2 and human umbilical vein endothelial cells (HUVEC) was studied to examine mechanisms related to brain abscess formation. Two of 9 strains invaded HEp-2 cells and 0 of 6 invaded HUVEC better than the others. C. diversus survived at least 20 h within HEp-2 cells (in decreasing numbers). Adhesion to HEp-2 cells was increased in 3 of 4 strains expressing type 1 fimbriae, but this did not correlate with increased invasion. Inhibition of RNA or protein synthesis blocked invasion but not adhesion. Thus, invasion requires ongoing protein synthesis, and adhesion to and invasion of HEp-2 cells by type-1-fimbriated strains are independent steps. Invasion was inhibited by cytochalasin D. A 32-kDa protein found in cerebrospinal fluid isolates of C. diversus was not related to invasion of either cell line. Ability to invade HEp-2 cells was not increased among strains isolated from central nervous system sources.

Evaluation of progesterone treatment to create a model for equine endometritis.

To investigate a model for equine endometritis, 12 mares with normal reproductive tracts were divided into 2 groups. All mares received progesterone in oil, 250 mg im, daily. At 5 days after initiation of progesterone administration, the uteri were inoculated with 10(6) colony forming units of Pseudomonas aeruginosa. The day of inoculation was designated Day 0. On Day 6, endometrial swab samples yielded P. aeruginosa in 5 mares; samples from the other 7 mares yielded heavy growth of Escherichia coli, Streptococcus zooepidemicus, Klebsiella pneumoniae, Enterobacter spp., Citrobacter diversus, Staphylococcus epidermidis and Streptococcus morbillorum. On Days 6, 7 and 8, Group A mares received intrauterine infusions of 6 g ticarcillin disodium and 0.2 g clavulanate potassium in 100 ml sterile saline. Group B mares received infusions of saline only. The incidence of swab specimens yielding no bacterial growth was significantly higher in Group A than Group B mares on Days 8 and 13 (4/6 vs 0/6). Swab samples from 5 of the 6 mares in Group A yielded growth of fungi on Days 13 and 19. Mares in Group B were then similarly treated with ticarcillin/clavulanate infusions, on Days 19, 20 and 21. The incidence of swab specimens yielding no bacterial growth was 2/6 and 1/6 on Days 21 and 26, respectively; fungi were not recovered from these mares at any time. The incidence of no-growth swabs after antibiotic treatment tended to be higher in Group A and incidence of fungal recovery after antibiotic treatment was significantly higher in Group A.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of the autoSCAN-W/A rapid system for identification and susceptibility testing of gram-negative fermentative bacilli.

The autoSCAN-Walk-Away (W/A) system for identification and susceptibility testing was evaluated for 400 gram-negative fermentative bacteria by using the API 20E (366 isolates) and/or tube biochemical tests as the reference identification system and a frozen microdilution MIC tray system for susceptibility testing. The W/A system performed well for identification of this group of organisms representing 14 genera and 30 species, showing a sensitivity of 96% and results available in 2 h. Of the 16 misidentifications, 6 were with Serratia liquefaciens. A total of 63 isolates (17%) required further tests to complete the identification, compared with 106 (29%) of the isolates which required additional tests for the API 20E identification. Approximately half (32) of the additional tests with the W/A system were required in order to separate Citrobacter diversus from C. amalonaticus. For susceptibility determinations, the W/A system demonstrated an overall agreement of 93% (4,102 determinations) with 40 major errors (0.98%). However, of the 906 resistant organism-drug combinations in the study, there were 115 very major errors, for a false-susceptibility rate of 12.7% of the resistance determinations. Among these very major errors, 80% occurred with piperacillin and the cephalosporins. The W/A system completed the MIC determinations in 7 h; however, the difficulty in detecting resistance with some antimicrobial agents limited the advantages of the rapid susceptibility testing.

Review of the in vitro antibacterial activity of cefprozil, a new oral cephalosporin.

Cefprozil is a newer oral cephalosporin with a spectrum of activity against organisms that include gram-positive and gram-negative pathogens. A review of published data shows that cefprozil is active (susceptibility, less than or equal to 8 micrograms/mL; moderate susceptibility, 16 micrograms/mL; resistance, greater than or equal to 32 micrograms/mL) against gram-positive species such as streptococci, methicillin-susceptible staphylococci, and Listeria monocytogenes; it may have marginal activity against some enterococci. Among the gram-negative species, cefprozil has activity against Escherichia coli, Proteus mirabilis, Citrobacter diversus, Klebsiella pneumoniae, Klebsiella oxytoca, Haemophilus influenzae, and Moraxella catarrhalis. For anaerobic species, cefprozil has activity against clostridial species, including Clostridium difficile, peptostreptococci, and possibly Bacteroides melaninogenicus and Eubacterium. The activity of cefprozil is generally greater than that of cephalexin and generally similar to that of cefaclor. In these reports, cefprozil showed more in vitro activity than cephalexin and cefaclor against penicillin-resistant pneumococci, penicillin-resistant viridans streptococci, beta-lactamase-positive methicillin-susceptible Staphylococcus aureus, and C. difficile, although the clinical significance of some of these differences has yet to be studied.

In vitro activity of cefquinome, a new cephalosporin, compared with other cephalosporin antibiotics

The in vitro activity of cefquinome, a new aminothiazolyl cephalosporin with a C-3 bicyclic pyridinium group, was compared with ceftazidime, cefpirome, and cefepime. Cefquinome inhibited members of the Enterobacteriaceae at ≤ 0.5 μg/ml for Escherichia coli, Klebsiella pneumoniae, K. oxytoca, Citrobacter diversus, Salmonella Shigella, Proteus mirabilis, Morganella, and Providencia. Although most Citrobacter freundii and Enterobacter cloacae were inhibited by < 2 μg/ml, some strains resistant to ceftazidime were resistant, [minimum inhibitory concentration (MIC) > 16 μg/ml]. Serratia marcescens were inhibited by < 1 μg/ml and Pseudomonas aeruginosa by 8 μg/ml similar to the activity of cefepime. The majority of Haemophilus influenzae and Neisseria gonorrhoeae were inhibited by < 0.25 μg/ml. Most enterococci had cequinome MICs of 4–8 μg/ml. Cefquinome was extremely active against group-A streptococci and Streptococcus pneumoniae with MICs < 0.12 μg/ml. 90% of methicillin-susceptible Staphylococcus aureus 90% were inhibited by 2 μg/ml. Overall, the in vitro activity of cefquinome was comparable with aminothiazolyl cephalosporins. It inhibited some Enterobacter and Citrobacter freundii resistant to ceftazidime as did cefpirome and cefepime. Cefquinome was not destroyed by the common plasmid β-lactamases TEM-1, TEM-2, SHV-1, or by the chromosomal β-lactamases of Klebsiella, Branhamella, and Pseudomonas, but it was hydrolyzed by TEM-3, TEM-5, and TEM-9. Its activity was not adversely decreased in different medium or protein, and minimum bactericidal concentrations (MBCs) for most species except for Enterobacter were within a dilution of MICs.

Anaerobic malonate decarboxylation by Citrobacter diversus. Growth and metabolic studies, and evidence of ATP formation.

Citrobacter diversus ATCC 27156 was able to grow by decarboxylation of malonate to acetate under strictly anaerobic conditions, in the presence of yeast extract. The growth yield, corrected for growth on yeast extract, was 2.03 g cell dry mass per mol malonate. The addition of malonate to ATP-depleted cell suspensions (less than 0.2 nmol ATP/mg cell protein) resulted in a rapid increase in cellular ATP levels to between 4.5 and 6.0 nmol/mg cell protein. Intact cells decarboxylated malonate at rates of up to 1.5 mumol/min.mg protein. Enzyme assays on malonate-grown cells indicated activation of malonate by an ATP-dependent ligase reaction and by CoA transfer from acetyl-CoA, followed by decarboxylation of malonyl-CoA to acetyl-CoA with subsequent recovery of the invested ATP by substrate level phosphorylation through the activity of acetate kinase. Net ATP synthesis is postulated to be mediated by gradient formation coupled to the decarboxylation of malonyl-CoA. The protonophore CCCP and H(+)-ATPase inhibitor DCCD significantly reduced cellular ATP levels, suggesting a role for proton gradients in the energy metabolism of this strain when growing an malonate. Inhibitors of sodium metabolism or ommission of sodium had no effect on ATP levels or malonate decarboxylation.

Reduction of Campylobacter jejuni colonization of chicks by cecum-colonizing bacteria producing anti-C. jejuni metabolites.

Cecum-colonizing bacteria were isolated from Campylobacter jejuni-free White Leghorn (Gallus domesticus) laying hens and screened for the ability to produce anti-C. jejuni metabolites. Nine isolates were obtained that possessed this characteristic. The peroral administration of the nine isolates as a mixture (ca. 10(9) per chick) to 1-day-old chicks was followed 1 week later by peroral inoculation of Campylobacter jejuni (ca. 10(9) per chick) to determine if the cecal isolates could protect chicks from colonization by campylobacters. The nine-strain mixture of cecal bacteria provided from 41 to 85% protection from C. jejuni colonization. The protective bacteria were reduced to a mixture of three strains on the basis of their ability to utilize mucin as a sole substrate for growth. These strains included Klebsiella pneumoniae 23, Citrobacter diversus 22, and Escherichia coli (O13:H-) 25. Four feeding trials with this three-strain mixture provided from 43 to 100% (average, 78%) protection from C. jejuni colonization. The dominant cecal bacterium of chicks treated with the three-strain mixture was consistently E. coli O13:H-. Similarly, three trials with only E. coli 25 used as the protective bacterium resulted in 49 to 72% (average, 59%) protection from C. jejuni colonization, with E. coli O13:H- being the dominant cecal bacterium in all cases. Although not completely effective, E. coli 25 substantially reduced the incidence of C. jejuni colonization of chicks. For all trials, fewer C. jejuni were present in the ceca of colonized chicks receiving the protective bacteria before exposure to C. jejuni than in chicks receiving only C. jejuni.(ABSTRACT TRUNCATED AT 250 WORDS)

Long term epidemiological analysis of Citrobacter diversus in a neonatal intensive care unit

A prolonged outbreak of Citrobacter diversus central nervous system infection among hospitalized term infants, peaking in 1979, ceased with establishment of nurse-patient cohorting. The outbreak was attributed to dissemination of an epidemic strain among infants in an antiquated neonatal intensive care unit. When C. diversus colonization recurred within the new neonatal intensive care unit in 1984, cohorting and bacteriologic surveillance were reinstituted. By utilizing biotypes, plasmid profiles and antibiograms, four different C. diversus strains were identified circulating during 1979. Strains recovered between 1984 and 1988 from neonatal intensive care unit infants were similar to those from community-acquired sources. A strain considered avirulent in 1979 was found causing bacteremia in two infants (one with central nervous system disease) in 1984 to 1988. During cohorting C. diversus acquisition was 0.019/patient-month; after cohorting ceased it was 0.017/patient-month. Multiple source introductions appeared to occur with different C. diversus strains, some causing infant disease. No efficacy of cohorting was evident.

β-Lactamase Induction Antagonizes β-Lactam Susceptibilities inCitrobacter diversusandEnterobacter cloacaeClinical Isolates

Inducible beta-lactamases were obtained after exposure to several beta-lactams in clinical isolates of Enterobacter cloacae and Citrobacter diversus. Enzyme production was related to the inducer and medium composition. beta-lactamase is able to inactivate only labile compounds, thus generating minimum inhibitory concentrations higher than in the absence of the inducer; imipenem susceptibilities usually were not changed.