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  1. Fulltext Genome sequence of Citrobacter sp. strain A1, a dye-degrading bacterium
    Chan GF, Gan HM, Rashid NA
    J Bacteriol, 2012 Oct;194(19):5485-6.
    PMID: 22965102 DOI: 10.1128/JB.01285-12
    Citrobacter sp. strain A1, isolated from a sewage oxidation pond, is a facultative aerobe and mesophilic dye-degrading bacterium. This organism degrades azo dyes efficiently via azo reduction and desulfonation, followed by the successive biotransformation of dye intermediates under an aerobic environment. Here we report the draft genome sequence of Citrobacter sp. A1.
    Matched MeSH terms: Citrobacter/classification*; Citrobacter/genetics*; Citrobacter/metabolism
  2. Fulltext Isolated sphenoid sinus lesion: A diagnostic dilemma
    Alazzawi S, Shahrizal T, Prepageran N, Pailoor J
    Qatar Med J, 2014;2014(1):57-60.
    PMID: 25320694 DOI: 10.5339/qmj.2014.10
    Isolated sphenoid sinus lesions are an uncommon entity and present with non-specific symptoms. In this case report, the patient presented with a history of headaches for a duration of one month without sinonasal symptoms. A computed tomography scan showed a soft tissue mass occupying the sphenoid sinus. An endoscopic biopsy revealed fungal infection. Endoscopic wide sphenoidotomy with excision of the sphenoid sinus lesion was then performed however, the microbiological examination post-surgery did not show any fungal elements. Instead, Citrobacter species was implicated to be the cause of infection.
    Matched MeSH terms: Citrobacter
  3. Fulltext Toxic effect of high concentration of sonochemically synthesized polyvinylpyrrolidone-coated silver nanoparticles on Citrobacter sp. A1 and Enterococcus sp. C1
    Lau CP, Abdul-Wahab MF, Jaafar J, Chan GF, Abdul Rashid NA
    J Microbiol Immunol Infect, 2017 Aug;50(4):427-434.
    PMID: 26427880 DOI: 10.1016/j.jmii.2015.08.004
    BACKGROUND/PURPOSE: Currently, silver nanoparticles (AgNPs) have gained importance in various industrial applications. However, their impact upon release into the environment on microorganisms remains unclear. The aim of this study was to analyze the effect of polyvinylpyrrolidone-capped AgNPs synthesized in this laboratory on two bacterial strains isolated from the environment, Gram-negative Citrobacter sp. A1 and Gram-positive Enterococcus sp. C1.

    METHODS: Polyvinylpyrrolidone-capped AgNPs were synthesized by ultrasound-assisted chemical reduction. Characterization of the AgNPs involved UV-visible spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, and energy dispersive X-ray spectroscopy. Citrobacter sp. A1 and Enterococcus sp. C1 were exposed to varying concentrations of AgNPs, and cell viability was determined. Scanning electron microscopy was performed to evaluate the morphological alteration of both species upon exposure to AgNPs at 1000 mg/L.

    RESULTS: The synthesized AgNPs were spherical in shape, with an average particle size of 15 nm. The AgNPs had different but prominent effects on either Citrobacter sp. A1 or Enterococcus sp. C1. At an AgNP concentration of 1000 mg/L, Citrobacter sp. A1 retained viability for 6 hours, while Enterococcus sp. C1 retained viability only for 3 hours. Citrobacter sp. A1 appeared to be more resistant to AgNPs than Enterococcus sp. C1. The cell wall of both strains was found to be morphologically altered at that concentration.

    CONCLUSION: Minute and spherical AgNPs significantly affected the viability of the two bacterial strains selected from the environment. Enterococcus sp. C1 was more vulnerable to AgNPs, probably due to its cell wall architecture and the absence of silver resistance-related genes.

    Matched MeSH terms: Citrobacter/drug effects*; Citrobacter/isolation & purification; Citrobacter/physiology
  4. Characterization of quorum sensing genes and N-acyl homoserine lactones in Citrobacter amalonaticus strain YG6
    Kher HL, Krishnan T, Letchumanan V, Hong KW, How KY, Lee LH, et al.
    Gene, 2019 Feb 05;684:58-69.
    PMID: 30321658 DOI: 10.1016/j.gene.2018.10.031
    In the phylum of Proteobacteria, quorum sensing (QS) system is widely driven by synthesis and response of N-acyl homoserine lactone (AHL) signalling molecules. AHL is synthesized by LuxI homologue and sensed by LuxR homologue. Once the AHL concentration achieves a threshold level, it triggers the regulation of target genes. In this study, QS activity of Citrobacter amalonaticus strain YG6 which was isolated from clams was investigated. In order to characterise luxI/R homologues, the genome of C. amalonaticus strain YG6 (4.95 Mbp in size) was sequenced using Illumina MiSeq sequencer. Through in silico analysis, a pair of canonical luxI/R homologues and an orphan luxR homologue were identified and designated as camI, camR, and camR2, respectively. A putative lux box was identified at the upstream of camI. The camI gene was cloned and overexpressed in E. coli BL21 (DE3)pLysS. High-resolution triple quadrupole liquid chromatography mass spectrometry (LC-MS/MS) analysis verified that the CamI is a functional AHL synthase which produced multiple AHL species, namely N‑butyryl‑l‑homoserine lactone (C4-HSL), N‑hexanoyl‑l‑homoserine lactone (C6-HSL), N‑octanoyl‑l‑homoserine lactone (C8-HSL), N‑tetradecanoyl‑l‑homoserine lactone (C14-HSL) and N‑hexadecanoyl‑l‑homoserine lactone (C16-HSL) in C. amalonaticus strain YG6 and camI gene in recombinant E. coli BL21(DE3)pLysS. To our best knowledge, this is the first functional study report of camI as well as the first report describing the production of C14-HSL by C. amalonaticus.
    Matched MeSH terms: Citrobacter/genetics; Citrobacter/metabolism
  5. Fulltext Data on whole-genome sequencing of extended-spectrum beta-lactamases producing Enterobacteriaceae isolates from Malaysia
    Gan HM, Eng WWH, Dhanoa A
    Data Brief, 2019 Aug;25:104257.
    PMID: 31384648 DOI: 10.1016/j.dib.2019.104257
    We report the whole genome sequencing data and de novo genome assemblies for eight extended-spectrum beta-lactamases (ESBL) producing Enterobacteriaceae isolates from Malaysia consisting of four Klebsiella pneumoniae, two Enterobacter harmaechei, one Citrobacter freundii and one Escherichia coli. We identified at least one ESBL gene in each genome, with blaCTX-M-15 being the most prevalent ESBL gene in the current genomic sampling.
    Matched MeSH terms: Citrobacter freundii
  6. Screening and production of Polyhydroxybutyrate (PHB) by bacterial strains isolated from Rhizosphere soil of groundnut plants
    Haliru Musa, Bolanle BB, Farizul Hafiz Kasim, Arbain D
    Sains Malaysiana, 2016;45:1469-1476.
    Polyhydroxybutyrate (PHB) otherwise known as bioplastics are biodegradable materials that are accumulated in various microorganisms to serve as carbon and energy reservoirs and regarded as an attractive alternative to petroleum-derived plastics. Although research has been conducted on isolation of PHB-producing microorganisms from different ecological environments, few studies have been carried out on isolation of potential PHB-producing microorganisms from rhizosphere environment of groundnut plants, Arachis hypogaea which can be regarded as a good environment for the isolation of potential PHB-producing microorganisms. In the present study, a total of twenty-one (21) bacterial strains were primarily screened and isolated from rhizosphere soil of a groundnut plant. Four bacterial isolates with maximum PHB-producing potential upon screening using submerged fermentation were selected for further studies. The fermentation pattern of PHB production was studied using different nutrient sources. The influence of agitation on PHB production was also studied. Mannitol stimulated maximum (6.076a mg/mL) PHB production by Bacillus sp. 1; KNO3 used as a limiting nutrient induced best (5.728a mg/mL) PHB production by Citrobacter sp. and MgSO4.7H2O supported maximum (5.972a mg/mL) PHB production in Enterococcus sp. A low agitation speed of 150 rpm was found to support best (5.802a mg/mL) PHB production by Bacillus sp.1. Findings from this study indicated that the isolated bacterial strains have high PHB- producing potential. The need to explore other environment harbouring microbial strains with high PHB-producing potential is paramount to the discovery of bioplastics with improved properties for potential industrial applications.
    Matched MeSH terms: Citrobacter
  7. Parametric and kinetic studies of activated sludge dewatering by cationic chitosan-like bioflocculant BF01314 produced from Citrobacter youngae
    Mohamed Hatta NS, Lau SW, Chua HB, Takeo M, Sen TK, Mubarak NM, et al.
    Environ Res, 2023 May 01;224:115527.
    PMID: 36822539 DOI: 10.1016/j.envres.2023.115527
    Bacterial strains belonging to Citrobacter spp. were reported to produce polysaccharides consisting of N-acetylglucosamine and glucosamine like chitosan, with high flocculation activity. In this work, the flocculation dewatering performance of activated sludge conditioned by a novel cationic chitosan-like bioflocculant (BF) named BF01314, produced from Citrobacter youngae GTC 01314, was evaluated under the influences of flocculant dosage, pH, and temperature. At BF dosage as low as 0.5 kg/t DS, the sludge dewaterability was significantly enhanced in comparison to the raw (untreated) sludge, featuring well-flocculated characteristic (reduction in CST from 22.0 s to 9.4 s) and good sludge filterability with reduced resistance (reduction in SRF by one order from 7.42 × 1011 to 9.59 × 1010 m/kg) and increased compactness of sludge (increase in CSC from 15.2 to 23.2%). Besides, the BF demonstrated comparable high sludge dewatering performance within the pH range between 2 and 8, and temperature range between 25 °C and 80 °C. Comparison between the BF, the pristine chitosan and the commercial cationic copolymer MF 7861 demonstrated equivalent performance with enhanced dewaterability at the dosage between 2.0 and 3.0 kg/t DS. Besides, the BF demonstrated strong flocculation activity (>99%) when added to the sludge suspension using moderate to high flocculation speeds (100-200 rpm) with at least 3-min mixing time. The BF's reaction in sludge flocculation was best fitted with a pseudo first-order kinetic model. Electrostatic charge patching and polymer bridging mechanisms are believed to be the dominant mechanistic phenomena during the BF's sludge conditioning process (coagulation-flocculation).
    Matched MeSH terms: Citrobacter
  8. Some interesting isolates from a diagnostic laboratory
    Lim PL
    J Clin Pathol, 1978 Mar;31(3):223-6.
    PMID: 641196
    Citrobacter koseri, Plesiomonas shigelloides, Edwardsiella tarda, Yersinia enterocolitica, Alkalescens dispar, Vibrio parahaemolyticus, and Vibrio alginolyticus were seven interesting microorganisms isolated recently in our diagnostic laboratory.
    Matched MeSH terms: Citrobacter/isolation & purification
  9. Fulltext Designing mRNA- and Peptide-Based Vaccine Construct against Emerging Multidrug-Resistant Citrobacter freundii: A Computational-Based Subtractive Proteomics Approach
    Naveed M, Hassan JU, Ahmad M, Naeem N, Mughal MS, Rabaan AA, et al.
    Medicina (Kaunas), 2022 Sep 27;58(10).
    PMID: 36295517 DOI: 10.3390/medicina58101356
    Background and Objectives: Citrobacter freundii (C. freundii) is an emerging and opportunistic Gram-negative bacteria of the human gastrointestinal tract associated with nosocomial and severe respiratory tract infections. It has also been associated with pneumonia, bloodstream, and urinary tract infections. Intrinsic and adaptive virulence characteristics of C. freundii have become a significant source of diarrheal infections and food poisoning among immune-compromised patients and newborns. Impulsive usage of antibiotics and these adaptive virulence characteristics has modulated the C. freundii into multidrug-resistant (MDR) bacteria. Conventional approaches are futile against MDR C. freundii. Materials and Methods: The current study exploits the modern computational-based vaccine design approach to treat infections related to MDR C. freundii. A whole proteome of C. freundii (strain: CWH001) was retrieved to screen pathogenic and nonhomologous proteins. Six proteins were shortlisted for the selection of putative epitopes for vaccine construct. Highly antigenic, nonallergen, and nontoxic eleven B-cell, HTL, and TCL epitopes were selected for mRNA- and peptide-based multi-epitope vaccine construct. Secondary and tertiary structures of the multi-epitope vaccine (MEVC) were designed, refined, and validated. Results: Evaluation of population coverage of MHC-I and MHC-II alleles were 72% and 90%, respectively. Docking MEVC with TLR-3 receptor with the binding affinity of 21.46 (kcal/mol) occurred through the mmGBSA process. Further validations include codon optimization with an enhanced CAI value of 0.95 and GC content of about 51%. Immune stimulation and molecular dynamic simulation ensure the antibody production upon antigen interaction with the host and stability of the MEVC construct, respectively. Conclusions: These interpretations propose a new strategy to combat MDR C. freundii. Further, in vivo and in vitro trials of this vaccine will be valuable in combating MDR pathogens.
    Matched MeSH terms: Citrobacter freundii*
  10. Fulltext Genome analysis of quorum sensing Cedecea neteri SSMD04 leads to identification of its novel signaling synthase (cneI), cognate receptor (cneR) and an orphan receptor
    Tan KH, Tan JY, Yin WF, Chan KG
    PeerJ, 2015;3:e1216.
    PMID: 26355540 DOI: 10.7717/peerj.1216
    Cedecea neteri is a very rare human pathogen. We have isolated a strain of C. neteri SSMD04 from pickled mackerel sashimi identified using molecular and phenotypics approaches. Using the biosensor Chromobacterium violaceum CV026, we have demonstrated the presence of short chain N-acyl-homoserine lactone (AHL) type quorum sensing (QS) activity in C. neteri SSMD04. Triple quadrupole LC/MS analysis revealed that C. neteri SSMD04 produced short chain N-butyryl-homoserine lactone (C4-HSL). With the available genome information of C. neteri SSMD04, we went on to analyse and identified a pair of luxI/R homologues in this genome that share the highest similarity with croI/R homologues from Citrobacter rodentium. The AHL synthase, which we named cneI(636 bp), was found in the genome sequences of C. neteri SSMD04. At a distance of 8bp from cneI is a sequence encoding a hypothetical protein, potentially the cognate receptor, a luxR homologue which we named it as cneR. Analysis of this protein amino acid sequence reveals two signature domains, the autoinducer-binding domain and the C-terminal effector which is typical characteristic of luxR. In addition, we found that this genome harboured an orphan luxR that is most closely related to easR in Enterobacter asburiae. To our knowledge, this is the first report on the AHL production activity in C. neteri, and the discovery of its luxI/R homologues, the orphan receptor and its whole genome sequence.
    Matched MeSH terms: Citrobacter rodentium
  11. Fulltext Citrobacter koseri bacteraemia complicated by paraspinal abscess and spondylodiscitis--a case report
    Shaharuddin NR, Leong CL, Chidambaram SK, Lee C
    Med J Malaysia, 2012 Jun;67(3):337-9.
    PMID: 23082432
    Paraspinal abscess and spondylodiscitis due to Citrobacter koseri is a very rare condition. We report a remarkable case of Citrobacter koseri bacteraemia complicated by paraspinal abscess and spondylodiscitis in a patient who has successfully been treated in our hospital. Our patient demonstrates one of the common challenges in the practice of infectious disease medicine, wherein an innocuous presentation may and often underlie a serious infection. This case report elucidates to us that the diagnosis of a paraspinal abscess and spondylodiscitis requires a high index of suspicion in at risk patient presenting with compatible signs and symptoms.
    Matched MeSH terms: Citrobacter koseri*
  12. Fulltext Communal microaerophilic-aerobic biodegradation of Amaranth by novel NAR-2 bacterial consortium
    Chan GF, Rashid NA, Chua LS, Ab llah N, Nasiri R, Ikubar MR
    Bioresour Technol, 2012 Feb;105:48-59.
    PMID: 22182471 DOI: 10.1016/j.biortech.2011.11.094
    A novel bacterial consortium, NAR-2 which consists of Citrobacter freundii A1, Enterococcus casseliflavus C1 and Enterobacter cloacae L17 was investigated for biodegradation of Amaranth azo dye under sequential microaerophilic-aerobic condition. The NAR-2 bacterial consortium with E. casseliflavus C1 as the dominant strain enhanced the decolorization process resulting in reduction of Amaranth in 30 min. Further aerobic biodegradation, which was dominated by C. freundii A1 and E. cloacae L17, allowed biotransformation of azo reduction intermediates and mineralization via metabolic pathways including benzoyl-CoA, protocatechuate, salicylate, gentisate, catechol and cinnamic acid. The presence of autoxidation products which could be metabolized to 2-oxopentenoate was elucidated. The biodegradation mechanism of Amaranth by NAR-2 bacterial consortium was predicted to follow the steps of azo reduction, deamination, desulfonation and aromatic ring cleavage. This is for the first time the comprehensive microaerophilic-aerobic biotransformation pathways of Amaranth dye intermediates by bacterial consortium are being proposed.
    Matched MeSH terms: Citrobacter/metabolism
  13. Isolations of enteric pathogens from synanthropic flies trapped in downtown Kuala Lumpur
    Sulaiman S, Othman MZ, Aziz AH
    J Vector Ecol, 2000 Jun;25(1):90-3.
    PMID: 10925800
    Four species of synanthropic flies were trapped in downtown Kuala Lumpur: Chrysomya megacephala, Chrysomya rufifacies, Musca domestica, and Musca sorbens. Burkholderia pseudomallei, the organism causing melioidosis, was the dominant bacteria isolated from Chrysomya megacephala. Klebsiella oxytoca, commonly associated with nosocomial infections, was commonly isolated from Chrysomya megacephala, Musca domestica, and Musca sorbens. Aeromonas hydrophila, the bacteria causing gastroenteritis, was predominantly isolated from Chrysomya megacephala and also from Musca domestica and Musca sorbens. A total of 18 bacterial species was isolated from the synanthropic flies trapped. Burkholderia pseudomallei had been reported for the first time.
    Matched MeSH terms: Citrobacter/isolation & purification
  14. Fulltext Corneal laceration caused by river crab
    Vinuthinee N, Azreen-Redzal A, Juanarita J, Zunaina E
    Clin Ophthalmol, 2015;9:203-6.
    PMID: 25678769 DOI: 10.2147/OPTH.S74548
    A 5-year-old boy presented with right eye pain associated with tearing and photophobia of 1-day duration. He gave a history of playing with a river crab when suddenly the crab clamped his fingers. He attempted to fling the crab off, but the crab flew and hit his right eye. Ocular examination revealed a right eye corneal ulcer with clumps of fibrin located beneath the corneal ulcer and 1.6 mm level of hypopyon. At presentation, the Seidel test was negative, with a deep anterior chamber. Culture from the corneal scrapping specimen grew Citrobacter diversus and Proteus vulgaris, and the boy was treated with topical gentamicin and ceftazidime eyedrops. Fibrin clumps beneath the corneal ulcer subsequently dislodged, and revealed a full-thickness corneal laceration wound with a positive Seidel test and shallow anterior chamber. The patient underwent emergency corneal toileting and suturing. Postoperatively, he was treated with oral ciprofloxacin 250 mg 12-hourly for 1 week, topical gentamicin, ceftazidime, and dexamethasone eyedrops for 4 weeks. Right eye vision improved to 6/9 and 6/6 with pinhole at the 2-week follow-up following corneal suture removal.
    Matched MeSH terms: Citrobacter koseri
  15. Fulltext Role of ampicillin-sulbactam: a district hospital’s experience in treating diabetic foot ulcers
    Ng, C. S., Vadivelu, M., Chan, K. Y.
    International e-Journal of Science, Medicine & Education, 2009;3(2):28-30.
    MyJurnal
    Abstract: Ampicillin-sulbactam combination is the most frequently prescribed antibiotic in diabetic foot ulcers. We conducted a retrospective study to evaluate the antibiotic sensitivity of bacteria isolated to this antibiotic. In 33 patients with diabetic foot ulcer (September 2008-March 2009), 67% were culture positive in which Citrobacter spp accounted for 36% of these isolates. The rest isolated included Pseudomonas aeruginosa (22%), Proteus spp (18%), Acinetobacter spp (9%), Klebsiella pneumoniae (5%), Escherichia coli (5%) and Staphylococcus aureus (5%). These isolates were more likely to be ampicillin-resistant (n=18) than were ampicillin-sensitive isolates (n=4). Ampicillin resistance has raised our concern about current practice of prescribing ampicillin/ sulbactam as monotherapy for majority of our patients with such ulcers.
    Matched MeSH terms: Citrobacter
  16. Fulltext The distribution and characteristics of bacteria in recreational river water of a community resort in Baram, Sarawak, Malaysian Borneo
    Lihan, S., Tian, P.K,, Chiew, T.S., Ching, C.L., Shahbudin, A., Hussain, H., et al.
    International Food Research Journal, 2017;24(5):2238-2245.
    MyJurnal
    Enterobacteriaceae is a large family within the Gram-negative bacteria that primarily inhabits in the gastrointestinal tract of human and animals. The bacteria within this group are readily survived in the environment with some species found living free in the water where energy sources are scarce, making them ideal indicators for faecal contamination of the river water. Some species within the family have been used as indicator for the presence of pathogenic bacteria whilst on the other hand some species have been directly associated with various diseases in human and animals. The main aim of this research study was to determine the distribution and characteristics of the Enterobacteriaceae in water samples collected from river and waterfalls within a community resort. The health risk associated with the bacteria was analysed with regard to their susceptibility to antibiotics. Samples were collected from surface water and water falling down directly from waterfalls of river within the community resort. The samples collected were plated onto Eosine Methylene Blue agar (EMBA) for the isolation of the Enterobacteriaceae. Bacterial colonies growing on the agar were randomly picked, purified, stocked and then identified using API 20E identification kit. DNA fingerprinting using (GTG)5-PCR was utilised to determine their genetic profiles before the isolates were grouped into a dendrogram using RAPDistance software package. The level of antibiotic susceptibility of the bacteria isolates was analysed using disc diffusion technique. This study confirmed the presence of Enterobacter, Klebsiella, Citrobacter, Pantoea and Serratia in the water samples with their single and multiple antibiotic resistance and susceptible characteristics. The dendrogram presented in this study shows genetic similarities and differences among the strains, suggesting while there is a potential for single distribution of a clone, there is also possibility of the distribution of different strains within species in the water environment. Therefore, awareness on the potential risk associated with genetically diverse intermediate and resistant enteric bacteria in the recreational water should be communicated to the public especially communities within the study area.
    Matched MeSH terms: Citrobacter
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