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Isotherm equilibria of Mn²⁺ biosorption in drinking water treatment by locally isolated Bacillus species and sewage activated sludge

Hasan HA, Abdullah SR, Kofli NT, Kamarudin SK

J Environ Manage, 2012 Nov 30;111:34-43.
PMID: 22813857 DOI: 10.1016/j.jenvman.2012.06.027

Manganese (Mn(2+)) is one of the inorganic contaminant that causes problem to water treatment and water distribution due to the accumulation on water piping systems. In this study, Bacillus sp. and sewage activated sludge (SAS) were investigated as biosorbents in laboratory-scale experiments. The study showed that Bacillus sp. was a more effective biosorbent than SAS. The experimental data were fitted to the Langmuir (Langmuir-1 & Langmuir-2), Freundlich, Temkin, Dubinin-Radushkevich (D-R) and Redlich-Peterson (R-P) isotherms to obtain the characteristic parameters of each model. Mn(2+) biosorption by Bacillus sp. was found to be significantly better fitted to the Langmuir-1 isotherm than the other isotherms, while the D-R isotherm was the best fit for SAS; i.e., the χ(2) value was smaller than that for the Freundlich, Temkin, and R-P isotherms. According to the evaluation using the Langmuir-1 isotherm, the maximum biosorption capacities of Mn(2+) onto Bacillus sp. and SAS were 43.5 mg Mn(2+)/g biomass and 12.7 mg Mn(2+)/g biomass, respectively. The data fitted using the D-R isotherm showed that the Mn(2+) biosorption processes by both Bacillus sp. and SAS occurred via the chemical ion-exchange mechanism between the functional groups and Mn(2+) ion.

Matched MeSH terms: Bacillus/metabolism*
Dietary administration of Bacillus thuringiensis on the cellular innate immune response of African catfish (Clarias gariepinus) against Aeromonas hydrophila

Reneshwary C, Rajalakshmi M, Marimuthu K, Xavier R

Eur Rev Med Pharmacol Sci, 2011 Jan;15(1):53-60.
PMID: 21381499

An experiment was conducted to evaluate the use of Bacillus thuringiensis (Bt) as a probiotic to enhance the cellular innate immune response of the African catfish (Clarias gariepinus) challenged with a bacterial fish pathogen, Aeromonas hydrophila.

Matched MeSH terms: Bacillus thuringiensis/immunology*
Fulltext Optimization of physical factors affecting the production of thermo-stable organic solvent-tolerant protease from a newly isolated halo tolerant Bacillus subtilis strain Rand

Abusham RA, Rahman RN, Salleh AB, Basri M

Microb Cell Fact, 2009 Apr 09;8:20.
PMID: 19356254 DOI: 10.1186/1475-2859-8-20

BACKGROUND: Many researchers have reported on the optimization of protease production; nevertheless, only a few have reported on the optimization of the production of organic solvent-tolerant proteases. Ironically, none has reported on thermostable organic solvent-tolerant protease to date. The aim of this study was to isolate the thermostable organic solvent-tolerant protease and identify the culture conditions which support its production. The bacteria of genus Bacillus are active producers of extra-cellular proteases, and the thermostability of enzyme production by Bacillus species has been well-studied by a number of researchers. In the present study, the Bacillus subtilis strain Rand was isolated from the contaminated soil found in Port Dickson, Malaysia.
RESULTS: A thermostable organic solvent-tolerant protease producer had been identified as Bacillus subtilis strain Rand, based on the 16S rRNA analysis conducted, as well as the morphological characteristics and biochemical properties. The production of the thermostable organic solvent-tolerant protease was optimized by varying various physical culture conditions. Inoculation with 5.0% (v/v) of (AB600 = 0.5) inoculum size, in a culture medium (pH 7.0) and incubated for 24 h at 37 degrees C with 200 rpm shaking, was the best culture condition which resulted in the maximum growth and production of protease (444.7 U/ml; 4042.4 U/mg). The Rand protease was not only stable in the presence of organic solvents, but it also exhibited a higher activity than in the absence of organic solvent, except for pyridine which inhibited the protease activity. The enzyme retained 100, 99 and 80% of its initial activity, after the heat treatment for 30 min at 50, 55, and 60 degrees C, respectively.
CONCLUSION: Strain Rand has been found to be able to secrete extra-cellular thermostable organic solvent-tolerant protease into the culture medium. The protease exhibited a remarkable stability towards temperature and organic solvent. This unique property makes it attractive and useful to be used in industrial applications.

Matched MeSH terms: Bacillus; Bacillus subtilis
Fulltext Proteins of unknown function in the Protein Data Bank (PDB): an inventory of true uncharacterized proteins and computational tools for their analysis

Nadzirin N, Firdaus-Raih M

Int J Mol Sci, 2012;13(10):12761-72.
PMID: 23202924 DOI: 10.3390/ijms131012761

Proteins of uncharacterized functions form a large part of many of the currently available biological databases and this situation exists even in the Protein Data Bank (PDB). Our analysis of recent PDB data revealed that only 42.53% of PDB entries (1084 coordinate files) that were categorized under "unknown function" are true examples of proteins of unknown function at this point in time. The remainder 1465 entries also annotated as such appear to be able to have their annotations re-assessed, based on the availability of direct functional characterization experiments for the protein itself, or for homologous sequences or structures thus enabling computational function inference.

Matched MeSH terms: Bacillus subtilis/metabolism
Fulltext Gene knockout identification using an extension of Bees Hill Flux Balance Analysis

Choon YW, Mohamad MS, Deris S, Chong CK, Omatu S, Corchado JM

Biomed Res Int, 2015;2015:124537.
PMID: 25874200 DOI: 10.1155/2015/124537

Microbial strain optimisation for the overproduction of a desired phenotype has been a popular topic in recent years. Gene knockout is a genetic engineering technique that can modify the metabolism of microbial cells to obtain desirable phenotypes. Optimisation algorithms have been developed to identify the effects of gene knockout. However, the complexities of metabolic networks have made the process of identifying the effects of genetic modification on desirable phenotypes challenging. Furthermore, a vast number of reactions in cellular metabolism often lead to a combinatorial problem in obtaining optimal gene knockout. The computational time increases exponentially as the size of the problem increases. This work reports an extension of Bees Hill Flux Balance Analysis (BHFBA) to identify optimal gene knockouts to maximise the production yield of desired phenotypes while sustaining the growth rate. This proposed method functions by integrating OptKnock into BHFBA for validating the results automatically. The results show that the extension of BHFBA is suitable, reliable, and applicable in predicting gene knockout. Through several experiments conducted on Escherichia coli, Bacillus subtilis, and Clostridium thermocellum as model organisms, extension of BHFBA has shown better performance in terms of computational time, stability, growth rate, and production yield of desired phenotypes.

Matched MeSH terms: Bacillus subtilis/genetics*
Distribution of clostridial cry-like genes among Bacillus thuringiensis and Clostridium strains

Barloy F, Lecadet MM, Delécluse A

Curr Microbiol, 1998 Apr;36(4):232-7.
PMID: 9504991

The presence of two cry-like genes first identified in Clostridium bifermentans subsp. malaysia CH18 was investigated in Clostridium species including 12 subspecies of Clostridium bifermentans, 13 strains of other members of Clostridia genus, and 13 different subspecies of Bacillus thuringiensis. Oligonucleotides designed to amplify the two toxin genes, cmb71 and cmb72, were used. We found that these genes are present in 80% of the Clostridium bifermentans strains tested and in 8% of the other Clostridium and Bacillus thuringiensis strains.

Matched MeSH terms: Bacillus thuringiensis/genetics*
Fulltext An outbreak of Bacillus cereus food poisoning in a school hostel, Klang

Rampal L, Jegathesan M, Lim YS

Med J Malaysia, 1984 Jun;39(2):116-22.
PMID: 6439984

A food poisoning outbreak affected 114 female Malay students staying in a religious secondary school hostel in Klang. The students developed an illness mainly characterized by abdominal pain, nausea, vomiting and giddiness. The median incubation period in this outbreak was 2.5 hours. Laboratory examination of suspected food revealed 2.3 X10^6 Bacillus cereus organisms per gram of fried noodles. B. cereus was determined as the probable cause of this outbreak and the fried. noodles the most likely vehicle for the organism. An outbreak of B. cereus food poisoning is being reported in Malaysia for the first time.

Matched MeSH terms: Bacillus cereus/pathogenicity
Bacillus sphaericus strain 2297: nucleotide sequence of 41.9 kDa toxin gene

Hindley J, Berry C

Nucleic Acids Res, 1988 May 11;16(9):4168.
PMID: 3375083
Matched MeSH terms: Bacillus/genetics*
A new serovar of Bacillus thuringiensis possessing 28a28c flagellar antigenic structure: Bacillus thuringiensis serovar jegathesan, selectively toxic against mosquito larvae

Seleena P, Lee HL, Lecadet MM

J Am Mosq Control Assoc, 1995 Dec;11(4):471-3.
PMID: 8825511

A novel Bacillus thuringiensis strain highly toxic to mosquitoes was isolated from soil samples in Malaysia. This strain was shown to display a new subfraction of the H-28 flagellar antigen determining a new serovar H28a28c, which was designated serovar jegathesan. Bioassays indicated that Culex quinquefasciatus larvae are the most susceptible to this new isolate, whereas toxicity to Anopheles maculatus and Aedes aegypti larvae was 10 times lower. The potency of this new serotype is also comparable to most of the Malaysian B. thuringiensis H-14 isolates.

Matched MeSH terms: Bacillus thuringiensis/immunology*
Integration of Bacillus thuringiensis H-14 formulations and pyriproxyfen for the control of larvae of Aedes aegypti and Aedes albopictus

Lee YW, Zairi J, Yap HH, Adanan CR

J Am Mosq Control Assoc, 2005 Mar;21(1):84-9.
PMID: 15825767

Studies were carried out on the bioefficacy and residual activity of Bacillus thuringiensis israelensis H-14 (Bti) (water-dispersible granules of VectoBac ABG 6511 and liquid formulations of VectoBac 12AS) and pyriproxyfen (insect growth regulator, Sumilarv 0.5%) as direct applications for control of larvae of Aedes aegypti and Aedes albopictus. Two dosages of each Bti formulation (285 and 570 international toxic units [ITU]/liter) and the integration of both Bti formulations and pyriproxyfen were used for residual tests with 45-liter earthen jars for a period of 4 wk. In 1 test series, the treated water was replenished daily with 6 liters of seasoned untreated water. In the 2nd test series, the water in the jars was topped up to the 40-liter level during evaluation. Neither Bti formulation remained effective for a full week. Water-dispersible Bti granules provided effective initial control activity against Ae. aegypti and Ae. albopictus for both test designs (with replenishment and without replenishment of water). The higher dosage (570 ITU/liter) for both Bti formulations was only partially effective at the end of 1 wk after being diluted. After 1 wk, water-dispersible Bti granules provided greater larval mortality than did liquid Bti formulation against both mosquito species when integrated with pyriproxyfen. Pyriproxyfen (79.5 and 159 mg/liter) on its own showed low larvicidal activity but provided very effective control of adult emergence. In this study, integration of Bti (285 and 570 ITU/liter) with pyriproxyfen (79.5 mg/liter) extended the duration of partial larval control somewhat, but live larvae persisted throughout the 4-wk test. The integration effect was more obvious when water-dispersible Bti granules were integrated with pyriproxyfen than when liquid Bti was used. Integration of Bti with pyriproxyfen had a negative effect on adult emergence, which was completely inhibited by pyriproxyfen after day 1. Daily replenishment of water increased Bti activity and provided slightly better larval control. Aedes albopictus and Ae. aegypti were both completely susceptible to the higher concentration of Bti and pyriproxyfen in both test designs (with replenishment and without replenishment of water).

Matched MeSH terms: Bacillus thuringiensis*
Fulltext Microbiota of Palm Oil Mill Wastewater in Malaysia

Bala JD, Lalung J, Al-Gheethi AAS, Hossain K, Ismail N

Trop Life Sci Res, 2018 Jul;29(2):131-163.
PMID: 30112146 MyJurnal DOI: 10.21315/tlsr2018.29.2.10

This study was aimed at identifying indigenous microorganisms from palm oil mill effluent (POME) and to ascertain the microbial load. Isolation and identification of indigenous microorganisms was subjected to standard microbiological methods and sequencing of the 16S rRNA and 18S rRNA genes. Sequencing of the 16S rRNA and 18S rRNA genes for the microbial strains signifies that they were known as Micrococcus luteus 101PB, Stenotrophomonas maltophilia 102PB, Bacillus cereus 103PB, Providencia vermicola 104PB, Klebsiella pneumoniae 105PB, Bacillus subtilis 106PB, Aspergillus fumigatus 107PF, Aspergillus nomius 108PF, Aspergillus niger 109PF and Meyerozyma guilliermondii 110PF. Results revealed that the population of total heterotrophic bacteria (THB) ranged from 9.5 × 105 - 7.9 × 106 cfu/mL. The total heterotrophic fungi (THF) ranged from 2.1 × 104 - 6.4 × 104 cfu/mL. Total viable heterotrophic indigenous microbial population on CMC agar ranged from 8.2 × 105 - 9.1 × 106 cfu/mL and 1.4 × 103 - 3.4 × 103 cfu/mL for bacteria and fungi respectively. The microbial population of oil degrading bacteria (ODB) ranged from 6.4 × 105 - 4.8 × 106 cfu/mL and the oil degrading fungi (ODF) ranged from 2.8 × 103 - 4.7 × 104 cfu/mL. The findings revealed that microorganisms flourish well in POME. Therefore, this denotes that isolating native microorganisms from POME is imperative for effectual bioremediation, biotreatment and biodegradation of industrial wastewaters.

Matched MeSH terms: Bacillus cereus; Bacillus subtilis
Fulltext Field evaluation of Bacillus thuringiensis H-14 against Aedes mosquitoes

Lee YW, Zairi J

Trop Biomed, 2006 Jun;23(1):37-44.
PMID: 17041550 MyJurnal

Studies were carried out on the residual efficacy of Bacillus thuringiensis H-14 (water dispersible granule, VectoBac ABG 6511) as direct application in the control of Aedes larvae in the field. Field Aedes sp populations in the earthen and glass jars were predetermined before initiation of the trial. On confirmation of the presence of Aedes species in the designated area, Sungai Nibong Kecil, Penang Island, Malaysia, Bti was introduced in the 55L earthen and 3L glass jars). Two test designs were carried out. The first design had treated water replenished daily with 6L of seasoned water and the second design is without the replenishment of water but evaporated water was replenished. Bti was effective in the field for at least 35 days with more than 80% reduction in the Aedes larvae in the treated containers. For earthen jars with daily replenishment of water, 100% reduction was recorded for the first 3 days, while more than 80% reduction was recorded up to day 40. At day 60, Bti still provided an efficacy of 54.32 +/- 4.61 (%) of reduction. Whilst for earthen jars without daily replenishment of water, 100% reduction was recorded for the first 5 days, while more than 80% of reduction was recorded up to day 40. For the glass jars studied, similar efficacy was observed. In jars with daily replenishment of water a better larval control was observed. Percentage of reduction from day 50 to 60 for replenishment of water was between 50 to 70% compared to without replenishment of water with less than 40%.

Matched MeSH terms: Bacillus thuringiensis*
Fulltext Laboratory evaluation of Bacillus thuringiensis H-14 against Aedes aegypti

Lee YW, Zairi J

Trop Biomed, 2005 Jun;22(1):5-10.
PMID: 16880748

Laboratory efficacy and residual activity of a water dispersible granule formulation of Bacillus thuringiensis israelensis (Bti) at the dosages of 3000, 6000 and 15000 ITU/L were conducted in this study. The study was conducted in two different size containers, earthen jar (45 L) and glass jar (3 L) with or without daily replenishment of 6 L and 0.3 L of water in the earthen and glass jars, respectively. Results indicate that for both earthen jar and glass jar evaluations, Bti at the tested dosages, performed effectively against Aedes aegypti, giving a minimum of 42 days effective killing activity. When the dosage was increased from 3000 ITU/L to 6000 ITU/L or 15000 ITU/L, the effective periods of the Bti increased by an additional one to three weeks. The Bti water dispersible granule provided better larvicidal activity with replenishment of water compared with non-replenishment of water especially for the higher dosage (15000 ITU/L).

Matched MeSH terms: Bacillus thuringiensis*
Detoxification of Sap from Felled Oil Palm Trunks for the Efficient Production of Lactic Acid

Kunasundari B, Arai T, Sudesh K, Hashim R, Sulaiman O, Stalin NJ, et al.

Appl Biochem Biotechnol, 2017 Sep;183(1):412-425.
PMID: 28361245 DOI: 10.1007/s12010-017-2454-z

The availability of fermentable sugars in high concentrations in the sap of felled oil palm trunks and the thermophilic nature of the recently isolated Bacillus coagulans strain 191 were exploited for lactic acid production under non-sterile conditions. Screening indicated that strain 191 was active toward most sugars including sucrose, which is a major component of sap. Strain 191 catalyzed a moderate conversion of sap sugars to lactic acid (53%) with a productivity of 1.56 g/L/h. Pretreatment of oil palm sap (OPS) using alkaline precipitation improved the sugar fermentability, providing a lactic acid yield of 92% and productivity of 2.64 g/L/h. To better characterize potential inhibitors in the sap, phenolic, organic, and mineral compounds were analyzed using non-treated sap and saps treated with activated charcoal and alkaline precipitation. Phthalic acid, 3,4-dimethoxybenzoic acid, aconitic acid, syringic acid, and ferulic acid were reduced in the sap after treatment. High concentrations of Mg, P, K, and Ca were also precipitated by the alkaline treatment. These results suggest that elimination of excess phenolic and mineral compounds in OPS can improve the fermentation yield. OPS, a non-food resource that is readily available in bulk quantities from plantation sites, is a promising source for lactic acid production.

Matched MeSH terms: Bacillus/growth & development*
Fulltext Penicillin-Susceptible, Oxidase-Negative, Nonhemolytic, Nonmotile Bacillus megaterium in Disguise of Bacillus anthracis

Loong SK, Teoh BT, Johari J, Khor CS, Abd-Jamil J, Nor'e SS, et al.

Case Rep Infect Dis, 2017;2017:2578082.
PMID: 28331641 DOI: 10.1155/2017/2578082

Bacillus anthracis is a bacterial pathogen of major concern. The spores of this bacteria can survive harsh environmental conditions for extended periods and are well recognized as a potential bioterror weapon with significant implications. Accurate and timely identification of this Bacillus species in the diagnostic laboratory is essential for disease and public health management. Biosafety Level 3 measures and ciprofloxacin treatment were instituted when B. anthracis was suspected from a patient with gangrenous foot. 16S rDNA sequencing was performed to accurately identify the suspected bacterium, due to the superiority of this method to accurately identify clinically isolated bacteria. B. megaterium was identified as the causative agent and the organism was subsequently treated as a Biosafety Level 2 pathogen.

Matched MeSH terms: Bacillus; Bacillus anthracis
Fulltext Kinetic studies of the partially purified molybdenum-reducing enzyme from Bacillus pumilus strain Lbna

Abo-Shakeer, L.K.A., Rahman, M.F.A., Yakasai, H., Syed, M.A., Shukor M.Y., Bakar, N.A., et al.

Bioremediation Science and Technology Research, 2017;5(1):18-23.
MyJurnal

Bacterial based remediation of environmental toxicants is a promising innovative technology
for molybdenum pollution. To date, the enzyme responsible for molybdate reduction to Moblue
from bacteria show that the Michaelis-Menten constants varies by one order of magnitude.
It is important that the constants from newer enzyme sources be characterized so that a
comparison can be made. The aim of this study is to characterize kinetically the enzyme from a
previously isolated Mo-reducing bacterium; Bacillus pumilus strain Lbna. The maximum
activity of this enzyme occurred at pH 5.5 and in between 25 and 35 oC. The Km and Vmax of
NADH were 6.646 mM and 0.057 unit/mg enzyme, while the Km and Vmax of LPPM were 3.399
mM and 0.106 unit/mg enzyme. The results showed that the enzyme activity for Bacillus
pumilus strain Lbna were inhibited by all heavy metals used. Zinc, copper, silver, chromium,
cadmium and mercury all caused more than 50% inhibition to the Mo-reducing enzyme activity
with copper being the most potent with an almost complete inhibition of enzyme activity
observed.

Matched MeSH terms: Bacillus; Bacillus pumilus
Synergistic Antimicrobial Effect of a Seaweed-Probiotic Blend Against Acute Hepatopancreatic Necrosis Disease (AHPND)-Causing Vibrio parahaemolyticus

Lim SY, Loo KW, Wong WL

Probiotics Antimicrob Proteins, 2020 09;12(3):906-917.
PMID: 31773414 DOI: 10.1007/s12602-019-09616-8

The outbreak of acute hepatopancreatic necrosis disease (AHPND) has caused great economic losses to the shrimp culture sector. However, the use of antibiotics to fight this disease has resulted in negative impacts on human health and the environment. Thus, the use of natural alternatives to antibiotics may be a better solution. In this study, four Bacillus species obtained from the guts of shrimps (Fenneropenaeus penicillatus and Penaeus monodon) showed antimicrobial activity against the AHPND-causing Vibrio parahaemolyticus strain 3HP using the cross-streaking and agar spot methods. Two of the Bacillus isolates, B2 and BT, also showed good probiotic properties, exhibiting tolerance to bile, good adhesion to shrimp mucus, non-hemolytic, susceptibility to antibiotics and being safe towards hosts. Moreover, a seaweed-probiotic blend (a combination of Bacillus B2 and 20 mg/ml of the red seaweed Gracilaria sp.) exhibited synergistic in vitro inhibition against V. parahaemolyticus strain 3HP, with an observed inhibition zone of 5.0 mm. The broth co-culture experiment results further indicated that the seaweed-probiotic blend inhibited V. parahaemolyticus through competitive exclusion. The in vivo challenge trials also confirmed that this seaweed-probiotic blend significantly reduced the mortality of shrimps post-challenge with the AHPND-causing V. parahaemolyticus strain 3HP (p < 0.05) compared to the negative control (mortality rate = 13.88% vs 72.19%). Thus, this seaweed-probiotic blend may serve as an alternative to antibiotics in controlling the outbreak of AHPND.

Matched MeSH terms: Bacillus*
Field evaluation of Vectobac G, Vectobac 12AS and Bactimos WP against the dengue vector Aedes albopictus in tires

Sulaiman S, Pawanchee ZA, Wahab A, Jamal J, Sohadi AR

J Vector Ecol, 1997 Dec;22(2):122-4.
PMID: 9491362

The efficacy of three formulations of Bacillus thuringiensis var. israelensis was studied against Aedes albopictus in discarded tires. The formulations were: Vectobac G (corn cob formulation), Vectobac 12AS (aqueous suspension), and Bactimos WP (wettable powder formulation). Both Vectobac G and Vectobac 12AS were effective for 24 hr with more than 80% mortality. Both Vectobac formulations were significantly more effective than Bactimos WP for 24 hr after treatment (P < 0.0005). A week after treatment, Vectobac 12AS was significantly different than Bactimos WP (P < 0.05). However, Vectobac G did not differ significantly from Bactimos WP (P > 0.05); two weeks after spraying there was no significant difference among the various formulations (P > 0.05).

Matched MeSH terms: Bacillus thuringiensis*
Antioxidants improve β-cypermethrin degradation by alleviating oxidative damage and increasing bioavailability by Bacillus cereus GW-01

Xie Y, Gong L, Liu S, Yan J, Zhao S, Xia C, et al.

Environ Res, 2023 Nov 01;236(Pt 1):116680.
PMID: 37500036 DOI: 10.1016/j.envres.2023.116680

Microbial degradation of pesticide residues has the potential to reduce their hazards to human and environmental health. However, in some cases, degradation can activate pesticides, making them more toxic to microbes. Here we report on the β-cypermethrin (β-CY) toxicity to Bacillus cereus GW-01, a recently described β-CY degrader, and effects of antioxidants on β-CY degradation. GW-01 exposed to β-CY negatively affected the growth rate. The highest maximum specific growth rate (μm) appeared at 25 mg/L β-CY. β-CY induced the oxidative stress in GW-01. The activities of superoxide dismutase (SOD), catalyse (CAT), and glutathione-S-transferase (GST) were significantly higher than that in control (p

Matched MeSH terms: Bacillus cereus/metabolism
Fulltext Prevalence and associated factors of delayed sputum smear conversion in patients treated for smear positive pulmonary tuberculosis: A retrospective follow up study in Sabah, Malaysia

Khor LA, A Wahid UNI, Ling LL, Liansim SMS, Oon J, Balakrishnan MN, et al.

PLoS One, 2023;18(3):e0282733.
PMID: 36877714 DOI: 10.1371/journal.pone.0282733

INTRODUCTION: Tuberculosis remains a major health problem globally and in Malaysia, particularly in the state of Sabah. Delayed sputum conversion is associated with treatment failure, drug-resistant tuberculosis and mortality. We aimed to determine the prevalence of delayed sputum conversion among smear positive pulmonary tuberculosis (PTB) patients and its associated factors in Sabah, Malaysia.
METHODS: A retrospective follow up study on all patients newly diagnosed with smear positive pulmonary tuberculosis from 2017 to 2019 was conducted at three government health clinics in Sabah, utilizing data from a national electronic tuberculosis database and medical records. Descriptive statistics and binary logistic regression were applied for data analysis. The outcome of the study was the sputum conversion status at the end of the two-month intensive treatment phase with either successful conversion to smear negative or non-conversion.
RESULTS: 374 patients were included in the analysis. Our patients were generally younger than 60 years old with no medical illness and varying proportions of tuberculosis severity as judged by radiographic appearance and sputum bacillary load upon diagnosis. Foreigners constituted 27.8% of our sample. 8.8% (confidence interval: 6.2-12.2) did not convert to smear negative at the end of the intensive phase. Binary logistic regression showed that older patients ≥60 years old (adjusted odds ratio, AOR = 4.303), foreigners (AOR = 3.184) and patients with higher sputum bacillary load at diagnosis [2+ (AOR = 5.061) and 3+ (AOR = 4.992)] were more likely to have delayed sputum smear conversion.
CONCLUSION: The prevalence of delayed sputum conversion in our study was considerably low at 8.8% with age ≥60 years old, foreigners and higher pre-treatment sputum bacillary load associated with delayed conversion. Healthcare providers should take note of these factors and ensure the patients receive proper follow up treatment.

Matched MeSH terms: Bacillus*; Lactobacillus casei*

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