Displaying publications 1 - 20 of 152 in total

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  1. Enhancement of anaerobic digestibility of waste activated sludge using photo-Fenton pretreatment
    Heng GC, Isa MH, Lim JW, Ho YC, Zinatizadeh AAL
    Environ Sci Pollut Res Int, 2017 Dec;24(35):27113-27124.
    PMID: 28963706 DOI: 10.1007/s11356-017-0287-5
    Biological treatments, such as activated sludge process, are common methods to treat municipal and industrial wastewaters. However, they produce huge amounts of waste activated sludge (WAS). The excess sludge treatment and disposal are a challenge for wastewater treatment plants due to economic, environmental, and regulatory factors. In this study, photo-Fenton pretreatment (oxidation using hydrogen peroxide and iron catalyst aided with UV light) was optimized using response surface methodology (RSM) and central composite design (CCD) to determine the effects of three operating parameters (H2O2 dosage, H2O2/Fe2+ molar ratio, and irradiation time) on disintegration and dewaterability of WAS. MLVSS removal, capillary suction time (CST) reduction, sCOD, and EPS were obtained as 70%, 25%, 12,000 mg/L, and 500 mg/L, respectively, at the optimal conditions, i.e., 725 g H2O2/kg TS, H2O2/Fe2+ molar ratio 80, and irradiation time 40 min. Two batch-fed completely mixed mesophilic anaerobic digesters were then operated at 15-day solid retention time (SRT) and 37 ± 0.5 °C to compare the digestibility of untreated and photo-Fenton pretreated sludge in terms of volatile solids (VS) reduction, COD removal, and biogas production at steady-state operations. Photo-Fenton pretreatment followed by anaerobic digestion of WAS was very effective and yielded 75.7% total VS reduction, 81.5% COD removal, and 0.29-0.31 m3/kg VSfed·d biogas production rate, compared to 40.7% total VS solid reduction, 54.7% COD removal, and 0.12-0.17 m3/kg VSfed·d biogas production rate for control. Thus, photo-Fenton can be a useful pretreatment step in sludge management.
    Matched MeSH terms: Waste Water/microbiology
  2. Fulltext Molecular characterization of multi-drug resistant Escherichia coli isolates from tropical environments in Southeast Asia
    Hara H, Yusaimi YA, Zulkeflle SNM, Sugiura N, Iwamoto K, Goto M, et al.
    J Gen Appl Microbiol, 2019 Jan 24;64(6):284-292.
    PMID: 29877296 DOI: 10.2323/jgam.2018.02.003
    The emergence of antibiotic resistance among multidrug-resistant (MDR) microbes is of growing concern, and threatens public health globally. A total of 129 Escherichia coli isolates were recovered from lowland aqueous environments near hospitals and medical service centers in the vicinity of Kuala Lumpur, Malaysia. Among the eleven antibacterial agents tested, the isolates were highly resistant to trimethoprim-sulfamethoxazole (83.7%) and nalidixic acid (71.3%) and moderately resistant to ampicillin and chloramphenicol (66.7%), tetracycline (65.1%), fosfomycin (57.4%), cefotaxime (57.4%), and ciprofloxacin (57.4%), while low resistance levels were found with aminoglycosides (kanamycin, 22.5%; gentamicin, 21.7%). The presence of relevant resistance determinants was evaluated, and the genotypic resistance determinants were as follows: sulfonamides (sulI, sulII, and sulIII), trimethoprim (dfrA1 and dfrA5), quinolones (qnrS), β-lactams (ampC and blaCTX-M), chloramphenicol (cmlA1 and cat2), tetracycline (tetA and tetM), fosfomycin (fosA and fosA3), and aminoglycosides (aphA1 and aacC2). Our data suggest that multidrug-resistant E. coli strains are ubiquitous in the aquatic systems of tropical countries and indicate that hospital wastewater may contribute to this phenomenon.
    Matched MeSH terms: Water Microbiology*; Waste Water/microbiology*
  3. Growth enhancement of effective microorganisms for bioremediation of crude oil contaminated waters
    Mukred AM, Abd-Hamid A, Hamzah A, Yusoff WM
    Pak J Biol Sci, 2008 Jul 01;11(13):1708-12.
    PMID: 18819623
    The bioremediation of polluted groundwater, wastewater aeration pond and biopond sites was investigated using bacteria isolated from these sites located at the oil refinery Terengganu Malaysia. Out of 62 isolates, only 16 isolates from groundwater (8) and wastewater aeration pond (3) and biopond (5) were chosen based on growth medium containing 1% (v/v) Tapis crude oil. Only four isolates; Acinetobacter faecalis, Staphylococcus sp., Pseudomonas putida and Neisseria elongata showed percentage biodegradation of crude oil more than 50% after 5 days using Mineral Salts Medium (MSM). The effect of physical parameters (temperature, pH and agitation) on growth by all four strains showed a maximum growth in MSM medium with 1% Tapis crude oil at 37 degrees C with pH 7 and agitation of 130 rpm.
    Matched MeSH terms: Water Microbiology
  4. Detection of Salmonella bacterium in drinking water using microring resonator
    Bahadoran M, Noorden AF, Mohajer FS, Abd Mubin MH, Chaudhary K, Jalil MA, et al.
    Artif Cells Nanomed Biotechnol, 2016;44(1):315-21.
    PMID: 25133457 DOI: 10.3109/21691401.2014.948549
    A new microring resonator system is proposed for the detection of the Salmonella bacterium in drinking water, which is made up of SiO2-TiO2 waveguide embedded inside thin film layer of the flagellin. The change in refractive index due to the binding of the Salmonella bacterium with flagellin layer causes a shift in the output signal wavelength and the variation in through and drop port's intensities, which leads to the detection of Salmonella bacterium in drinking water. The sensitivity of proposed sensor for detecting of Salmonella bacterium in water solution is 149 nm/RIU and the limit of detection is 7 × 10(-4)RIU.
    Matched MeSH terms: Drinking Water/microbiology
  5. Microalgae from the Selenastraceae as emerging candidates for biodiesel production: a mini review
    Yee W
    World J Microbiol Biotechnol, 2016 Apr;32(4):64.
    PMID: 26931604 DOI: 10.1007/s11274-016-2023-6
    Over the years, microalgae have been identified to be a potential source of commercially important products such as pigments, polysaccharides, polyunsaturated fatty acids and in particular, biofuels. Current demands for sustainable fuel sources and bioproducts has led to an extensive search for promising strains of microalgae for large scale cultivation. Prospective strains identified for these purposes were among others, mainly from the genera Hematococcus, Dunaliella, Botryococcus, Chlorella, Scenedesmus and Nannochloropsis. Recently, microalgae from the Selenastraceae emerged as potential candidates for biodiesel production. Strains from the Selenastraceae such as Monoraphidium sp. FXY-10, M. contortum SAG 47.80, Ankistrodesmus sp. SP2-15 and M. minutum were high biomass and lipid producers when cultivated under optimal conditions. A number of Selenastraceae strains were also reported to be suitable for cultivation in wastewater. This review highlights recent reports on potential strains from the Selenastraceae for biodiesel production and contrasts their biomass productivity, lipid productivity as well as fatty acid profile. Cultivation strategies employed to enhance their biomass and lipid productivity as well as to reduce feedstock cost are also discussed in this paper.
    Matched MeSH terms: Water Microbiology; Waste Water/microbiology
  6. Isolation and characterization of lytic vibriophage against Vibrio cholerae O1 from environmental water samples in Kelantan, Malaysia
    Al-Fendi A, Shueb RH, Ravichandran M, Yean CY
    J Basic Microbiol, 2014 Oct;54(10):1036-43.
    PMID: 24532381 DOI: 10.1002/jobm.201300458
    Water samples from a variety of sources in Kelantan, Malaysia (lakes, ponds, rivers, ditches, fish farms, and sewage) were screened for the presence of bacteriophages infecting Vibrio cholerae. Ten strains of V. cholerae that appeared to be free of inducible prophages were used as the host strains. Eleven bacteriophage isolates were obtained by plaque assay, three of which were lytic and further characterized. The morphologies of the three lytic phages were similar with each having an icosahedral head (ca. 50-60 nm in diameter), a neck, and a sheathed tail (ca. 90-100 nm in length) characteristic of the family Myoviridae. The genomes of the lytic phages were indistinguishable in length (ca. 33.5 kb), nuclease sensitivity (digestible with DNase I, but not RNase A or S1 nuclease), and restriction enzyme sensitivity (identical banding patterns with HindIII, no digestion with seven other enzymes). Testing for infection against 46 strains of V. cholerae and 16 other species of enteric bacteria revealed that all three isolates had a narrow host range and were only capable of infecting V. cholerae O1 El Tor Inaba. The similar morphologies, indistinguishable genome characteristics, and identical host ranges of these lytic isolates suggests that they represent one phage, or several very closely related phages, present in different water sources. These isolates are good candidates for further bio-phage-control studies.
    Matched MeSH terms: Water Microbiology*
  7. Molecular characterization of anaerobic sulfur-oxidizing microbial communities in up-flow anaerobic sludge blanket reactor treating municipal sewage
    Aida AA, Hatamoto M, Yamamoto M, Ono S, Nakamura A, Takahashi M, et al.
    J Biosci Bioeng, 2014 Nov;118(5):540-5.
    PMID: 24930844 DOI: 10.1016/j.jbiosc.2014.04.011
    A novel wastewater treatment system consisting of an up-flow anaerobic sludge blanket (UASB) reactor and a down-flow hanging sponge (DHS) reactor with sulfur-redox reaction was developed for treatment of municipal sewage under low-temperature conditions. In the UASB reactor, a novel phenomenon of anaerobic sulfur oxidation occurred in the absence of oxygen, nitrite and nitrate as electron acceptors. The microorganisms involved in anaerobic sulfur oxidation have not been elucidated. Therefore, in this study, we studied the microbial communities existing in the UASB reactor that probably enhanced anaerobic sulfur oxidation. Sludge samples collected from the UASB reactor before and after sulfur oxidation were used for cloning and terminal restriction fragment length polymorphism (T-RFLP) analysis of the 16S rRNA genes of the bacterial and archaeal domains. The microbial community structures of bacteria and archaea indicated that the genus Smithella and uncultured bacteria within the phylum Caldiserica were the dominant bacteria groups. Methanosaeta spp. was the dominant group of the domain archaea. The T-RFLP analysis, which was consistent with the cloning results, also yielded characteristic fingerprints for bacterial communities, whereas the archaeal community structure yielded stable microbial community. From these results, it can be presumed that these major bacteria groups, genus Smithella and uncultured bacteria within the phylum Caldiserica, probably play an important role in sulfur oxidation in UASB reactors.
    Matched MeSH terms: Waste Water/microbiology
  8. Biodegradation of 4-aminobenzenesulfonate by Ralstonia sp. PBA and Hydrogenophaga sp. PBC isolated from textile wastewater treatment plant
    Gan HM, Shahir S, Ibrahim Z, Yahya A
    Chemosphere, 2011 Jan;82(4):507-13.
    PMID: 21094980 DOI: 10.1016/j.chemosphere.2010.10.094
    A co-culture consisting of Hydrogenophaga sp. PBC and Ralstonia sp. PBA, isolated from textile wastewater treatment plant could tolerate up to 100 mM 4-aminobenzenesulfonate (4-ABS) and utilize it as sole carbon, nitrogen and sulfur source under aerobic condition. The biodegradation of 4-ABS resulted in the release of nitrogen and sulfur in the form of ammonium and sulfate respectively. Ninety-eight percent removal of chemical oxygen demand attributed to 20 mM of 4-ABS in cell-free supernatant could be achieved after 118 h. Effective biodegradation of 4-ABS occurred at pH ranging from 6 to 8. During batch culture with 4-ABS as sole carbon and nitrogen source, the ratio of strain PBA to PBC was dynamic and a critical concentration of strain PBA has to be reached in order to enable effective biodegradation of 4-ABS. Haldane inhibition model was used to fit the degradation rate at different initial concentrations and the parameters μ(max), K(s) and K(i) were determined to be 0.13 h⁻¹, 1.3 mM and 42 mM respectively. HPLC analyses revealed traced accumulation of 4-sulfocatechol and at least four unidentified metabolites during biodegradation. This is the first study to report on the characterization of 4-ABS-degrading bacterial consortium that was isolated from textile wastewater treatment plant.
    Matched MeSH terms: Water Microbiology
  9. Fulltext Genome sequence of Ralstonia sp. strain PBA, a bacterium involved in the biodegradation of 4-aminobenzenesulfonate
    Gan HM, Chew TH, Tay YL, Lye SF, Yahya A
    J Bacteriol, 2012 Sep;194(18):5139-40.
    PMID: 22933765 DOI: 10.1128/JB.01165-12
    Ralstonia sp. strain PBA was isolated from textile wastewater in a coculture with Hydrogenophaga sp. strain PBC. Here we present the assembly and annotation of its genome, which may provide further insights into the mechanism of its interaction with strain PBC during 4-aminobenzenesulfonate degradation.
    Matched MeSH terms: Water Microbiology
  10. Occurrence and contamination profiles of antibiotic resistance genes from swine manure to receiving environments in Guangdong Province southern China
    Wen X, Mi J, Wang Y, Ma B, Zou Y, Liao X, et al.
    Ecotoxicol Environ Saf, 2019 May 30;173:96-102.
    PMID: 30769208 DOI: 10.1016/j.ecoenv.2019.02.023
    Livestock farms are commonly regarded as the main sources of antibiotic resistance genes (ARGs), emerging pollutants with potential implications for human health, in the environment. This study investigated the occurrence and contamination profiles of nine ARGs of three types from swine manure to receiving environments (soil and water) in Guangdong Province, southern China. All ARGs occurred in 100% of swine manure samples. Moreover, the absolute concentration of total ARGs varied from 3.01 × 108 to 7.18 × 1014 copies/g, which was significantly higher than that in wastewater and manured soil (p  0.05). However, the number of ARGs (ermB, qnrS, acc(6')-Ib, tetM, tetO and tetQ) decreased but were not eliminated by wastewater treatment components (p 
    Matched MeSH terms: Waste Water/microbiology*
  11. Distribution of faecal indicator bacteria in tropical waters of Peninsular Malaysia and their decay rates in tropical seawater
    Wong YY, Lee CW, Chai SCY, Lim JH, Bong CW, Sim EUH, et al.
    Mar Pollut Bull, 2022 Dec;185(Pt A):114297.
    PMID: 36327936 DOI: 10.1016/j.marpolbul.2022.114297
    We investigated the appropriateness of faecal indicator bacteria in tropical waters. We compared total coliform (undetectable to 7.2 × 105 cfu 100 mL-1), faecal coliform (undetectable to 6.1 × 105 cfu 100 mL-1) and enterococci (undetectable to 3.1 × 104 cfu 100 mL-1) distribution in Peninsular Malaysia. Faecal indicator bacteria was highest in freshwater, and lowest in seawater (q > 4.18, p waters was not due to faecal pollution alone, and this will have serious implications towards the use of these faecal indicator bacteria.
    Matched MeSH terms: Water Microbiology
  12. Fulltext Investigating Escherichia coli habitat transition from sediments to water in tropical urban lakes
    Liu B, Lee CW, Bong CW, Wang AJ
    PeerJ, 2024;12:e16556.
    PMID: 38223759 DOI: 10.7717/peerj.16556
    BACKGROUND: Escherichia coli is a commonly used faecal indicator bacterium to assess the level of faecal contamination in aquatic habitats. However, extensive studies have reported that sediment acts as a natural reservoir of E. coli in the extraintestinal environment. E. coli can be released from the sediment, and this may lead to overestimating the level of faecal contamination during water quality surveillance. Thus, we aimed to investigate the effects of E. coli habitat transition from sediment to water on its abundance in the water column.

    METHODS: This study enumerated the abundance of E. coli in the water and sediment at five urban lakes in the Kuala Lumpur-Petaling Jaya area, state of Selangor, Malaysia. We developed a novel method for measuring habitat transition rate of sediment E. coli to the water column, and evaluated the effects of habitat transition on E. coli abundance in the water column after accounting for its decay in the water column.

    RESULTS: The abundance of E. coli in the sediment ranged from below detection to 12,000 cfu g-1, and was about one order higher than in the water column (1 to 2,300 cfu mL-1). The habitat transition rates ranged from 0.03 to 0.41 h-1. In contrast, the E. coli decay rates ranged from 0.02 to 0.16 h-1. In most cases (>80%), the habitat transition rates were higher than the decay rates in our study.

    DISCUSSION: Our study provided a possible explanation for the persistence of E. coli in tropical lakes. To the best of our knowledge, this is the first quantitative study on habitat transition of E. coli from sediments to water column.

    Matched MeSH terms: Water Microbiology
  13. Fulltext Resistance and resilience of small-scale recirculating aquaculture systems (RAS) with or without algae to pH perturbation
    Mohamed Ramli N, Giatsis C, Md Yusoff F, Verreth J, Verdegem M
    PLoS One, 2018;13(4):e0195862.
    PMID: 29659617 DOI: 10.1371/journal.pone.0195862
    The experimental set-up of this study mimicked recirculating aquaculture systems (RAS) where water quality parameters such as dissolved oxygen, pH, temperature, and turbidity were controlled and wastes produced by fish and feeding were converted to inorganic forms. A key process in the RAS was the conversion of ammonia to nitrite and nitrite to nitrate through nitrification. It was hypothesized that algae inclusion in RAS would improve the ammonia removal from the water; thereby improving RAS water quality and stability. To test this hypothesis, the stability of the microbiota community composition in a freshwater RAS with (RAS+A) or without algae (RAS-A) was challenged by introducing an acute pH drop (from pH 7 to 4 during three hours) to the system. Stigeoclonium nanum, a periphytic freshwater microalga was used in this study. No significant effect of the algae presence was found on the resistance to the acute pH drop on ammonia conversion to nitrite and nitrite conversion to nitrate. Also the resilience of the ammonia conversion to the pH drop disruption was not affected by the addition of algae. This could be due to the low biomass of algae achieved in the RAS. However, with regard to the conversion step of nitrite to nitrate, RAS+A was significantly more resilient than RAS-A. In terms of overall bacterial communities, the composition and predictive function of the bacterial communities was significantly different between RAS+A and RAS-A.
    Matched MeSH terms: Water Microbiology
  14. A shellfish-borne cholera outbreak in Malaysia
    Dutt AK, Alwi S, Velauthan T
    Trans R Soc Trop Med Hyg, 1971;65(6):815-8.
    PMID: 5157442
    Matched MeSH terms: Water Microbiology
  15. Cultivation of aerobic granular sludge for rubber wastewater treatment
    Rosman NH, Nor Anuar A, Othman I, Harun H, Sulong Abdul Razak MZ, Elias SH, et al.
    Bioresour Technol, 2013 Feb;129:620-3.
    PMID: 23317554 DOI: 10.1016/j.biortech.2012.12.113
    Aerobic granular sludge (AGS) was successfully cultivated at 27±1 °C and pH 7.0±1 during the treatment of rubber wastewater using a sequential batch reactor system mode with complete cycle time of 3 h. Results showed aerobic granular sludge had an excellent settling ability and exhibited exceptional performance in the organics and nutrients removal from rubber wastewater. Regular, dense and fast settling granule (average diameter, 1.5 mm; settling velocity, 33 m h(-1); and sludge volume index, 22.3 mL g(-1)) were developed in a single reactor. In addition, 96.5% COD removal efficiency was observed in the system at the end of the granulation period, while its ammonia and total nitrogen removal efficiencies were up to 94.7% and 89.4%, respectively. The study demonstrated the capabilities of AGS development in a single, high and slender column type-bioreactor for the treatment of rubber wastewater.
    Matched MeSH terms: Waste Water/microbiology*
  16. Level and transport pattern of faecal coliform bacteria from tropical urban catchments
    Chow MF, Yusop Z, Toriman ME
    Water Sci Technol, 2013;67(8):1822-31.
    PMID: 23579839 DOI: 10.2166/wst.2013.048
    Urbanization and frequent storms play important roles in increasing faecal bacteria pollution, especially for tropical urban catchments. However, only little information on the faecal bacteria levels from different land use types and the factors that influence bacteria concentrations is available. Thus, the objectives of this study were to quantify the levels and transport mechanism of faecal coliforms (FCs) from residential and commercial catchments. Stormwaters were sampled and the runoff flow rates were measured from both catchments during four storm events in Skudai, Malaysia. The samples were then analysed for FC, biochemical oxygen demand (BOD5), chemical oxygen demand (COD), total suspended solids (TSS) and ammoniacal-nitrogen (NH3-N) concentrations. Intra-storm and inter-storm characteristics of FC bacteria were investigated in order to identify the level and transport pattern of FC. The commercial catchment showed significantly higher event mean concentration (EMC) of FC than the residential catchment. For the residential catchment, the highest bacterial concentrations occurred during the early part of stormwater runoff with peak concentrations usually preceding the peak flow. First flush effect was more prevalent at the residential catchment.
    Matched MeSH terms: Water Microbiology*
  17. Fulltext Simultaneous biological nitrification and desulfurization treatment of ammonium and sulfide-rich wastewater: Effectiveness of a sequential batch operation
    Sekine M, Akizuki S, Kishi M, Kurosawa N, Toda T
    Chemosphere, 2020 Apr;244:125381.
    PMID: 31805460 DOI: 10.1016/j.chemosphere.2019.125381
    Sulfide inhibition to nitrifying bacteria has prevented the integration of digestate nitrification and biogas desulfurization to simplify anaerobic digestion systems. In this study, liquid digestate with NaHS solution was treated using nitrifying sludge in a sequential-batch reactor with a long fill period, with an ammonium loading rate of 293 mg-N L-1 d-1 and a stepwise increase in the sulfide loading rate from 0 to 32, 64, 128, and 256 mg-S L-1 d-1. Batch bioassays and microbial community analysis were also conducted with reactor sludge under each sulfide loading rate to quantify the microbial acclimatization to sulfide. In the reactor, sulfide was completely removed. Complete nitrification was maintained up to a sulfide load of 128 mg-S L-1 d-1, which is higher than that in previous reports and sufficient for biogas treatment. In the batch bioassays, the sulfide tolerance of NH4+ oxidizing activity (the 50% inhibitory sulfide concentration) increased fourfold over time with the compositional shift of nitrifying bacteria to Nitrosomonas nitrosa and Nitrobacter spp. However, the sulfur removal rate of the sludge slightly decreased, although the abundance of the sulfur-oxidizing bacteria Hyphomicrobium increased by 30%. Therefore, nitrifying sludge was probably acclimatized to sulfide not by the increasing sulfide removal rate but rather by the increasing nitrifying bacteria, which have high sulfide tolerance. Successful simultaneous nitrification and desulfurization were achieved using a sequential-batch reactor with a long fill period, which was effective in facilitating the present acclimatization.
    Matched MeSH terms: Waste Water/microbiology
  18. Clostridium perfringens and sulphite reducing clostridia densities in selected tropical Malaysian rivers
    Lee FC, Hakim SL, Kamaluddin MA, Thong KL
    Southeast Asian J. Trop. Med. Public Health, 2012 Jan;43(1):129-35.
    PMID: 23082563
    Clostridium perfringens (CP) and sulphite reducing clostridia (SRC) densities in the Selangor River, Bernam River and Tengi River Canal were examined between April 2007 and January 2008. Water samples were taken from two or three locations along each river, using either depth-integration or grab sampling methods. The downstream sampling site of the Selangor River, Rantau Panjang, reported the highest arithmetic mean of CP and SRC densities (583.45 and 8,120.08 cfu/100 ml, respectively). Both CP and SRC densities in the Selangor River increased further downstream, but the reverse was true in the Bernam River. The SRC densities in these rivers were significantly different from each other (p < 0.05) when comparing upstream and downstream results, but CP densities were not significantly different (p > 0.05). SRC densities were significantly correlated (p < 0.05) in different locations along the Selangor River and the Bernam River. The CP densities did not show such pattern (p > 0.05). River discharge had no significant correlation with SRC or CP densities by study site (p > 0.05). Since the Selangor River has a denser human population along its banks, this study confirms CP as a suitable indicator of human fecal contamination. However, tracing CP distribution along the river is more difficult than SRC. To our knowledge, this is the first study of CP and SRC densities from Malaysian rivers. CP densities found in this study were within the range of general water bodies reported from other countries.
    Matched MeSH terms: Water Microbiology*
  19. Pathogenic and saprophytic Leptospira species in water and soils from selected urban sites in peninsular Malaysia
    Benacer D, Woh PY, Mohd Zain SN, Amran F, Thong KL
    Microbes Environ, 2013;28(1):135-40.
    PMID: 23363618
    Leptospira species were studied in water and soils from selected urban sites in Malaysia. A total of 151 water (n=121) and soil (n=30) samples were collected from 12 recreational lakes and wet markets. All samples were filtered and inoculated into semi-solid Ellinghausen and McCullough modified by Johnson and Harris (EMJH) media supplemented with additional 5-fluorouracil. The cultures were then incubated at 30°C and observed under a dark field microscope with intervals of 10 days. A PCR assay targeting the rrs gene was used to confirm the genus Leptospira among the isolates. Subsequently, the pathogenic status of the isolates was determined using primer sets G1/G2 and Sapro1/Sapro2, which target the secY and rrs genes, respectively. The isolates were identified at serogroup level using the microscopic agglutination test (MAT) while their genetic diversity was assessed by pulsed field gel electrophoresis (PFGE). Based on dark field microscopy, 23.1% (28/121) water and 23.3% (7/30) soil cultures were positive for Leptospira spp. Of the 35 positive cultures, only 8 were pure and confirmed as Leptospira genus by PCR assay. Two out of 8 isolates were confirmed as pathogenic, 5 were saprophytic and one was intermediate. These 8 isolates were negative for the 25 reference hyperimmune rabbit sera tested in the MAT. PFGE showed that all 8 of these environmental Leptospira spp. were genetically diverse. In conclusion, the presence of pathogenic Leptospira spp. in the urban Malaysian environment may indicate and highlight the importance of water screening, especially in recreational lakes, in order to minimize any chance of Leptospira infection.
    Matched MeSH terms: Water Microbiology
  20. Melioidosis antibodies in Commonwealth soldiers
    Thin RN
    Lancet, 1976 Jan 3;1(7949):31-3.
    PMID: 54528 DOI: 10.1016/s0140-6736(76)92922-6
    Titres of melioidosis haemagglutinating antibodies of 1/40 or more were found in 18 of 905 British, Australian, and New Zealand soldiers serving in West Malaysia. Previous mild unsuspected melioidosis seemed to be responsible for these positive titres, which were more common in men exposed to surface water at work and during recreation. This accords with the current view that soil and surface water is the normal habitat of Pseudomonas pseudomallei, the causal organism. Pyrexia of unknown origin after arriving in Malaysia was significantly more common in men with titres of 1/40 or more than in the remainder. It is suggested that mild melioidosis may present as pyrexia of unknown origin. Pyrexias of unknown origin should be investigated vigorously in patients who are in or who have visited endemic areas.
    Matched MeSH terms: Water Microbiology
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