Group A Streptococcus isolated in Guyana with reduced susceptibility to β-lactam antibiotics
Introduction: Streptococcus pyogenes (Group A streptococci [GAS]) is the causative agent of pharyngitis and various other syndromes involving cellulitis streptococcal toxic shock syndrome (STSS) and necrotising fasciitis. Although the prevalence of GAS infections globally remains high necessitating the widespread use of [[EQUATION]]-lactam antibiotics GAS has remained largely susceptible to these agents. However there have been several reports of GAS with reduced susceptibility harbouring mutations in genes for penicillin-binding proteins (PBPs). The objectives of this study were to examine the in vitro β-lactam susceptibility patterns of Group A streptococci determine the prevalence of drug resistance and ascertain whether such resistance could be attributed to mutations in specific PBP genes.
Methods: In this study we sought to use Sanger sequencing to identify mutations in PBP genes of Streptococcus pyogenes isolated from patients that required inpatient and outpatient care that could confer reduced PBP affinity for penicillin and/or cephalosporin antibiotics. All isolates were screened for susceptibility to penicillin amoxicillin and cefazolin using E-test strips.
Results: While there were no documented cases of reduced susceptibility to penicillin or amoxicillin. Thirteen isolates had reduced susceptibility against cefazolin. Examination of pbp1a by Sanger sequencing revealed several isolates with single amino acid substitutions which could potentially reduce the affinity of PBP 1A for cefazolin and possibly other first-generation cephalosporins.
Conclusion: Penicillin and penicillin-derived antibiotics remain effective treatment options for GAS infections but active surveillance is needed to monitor for changes to susceptibility patterns against these and other antibiotics and understand the genetic mechanisms contributing to them.
Trend of Vancomycin resistance among Enterococcal meningitis patients in North India – an observational analysis
Introduction: Among bacterial meningitis enterococcal meningitis is extremely uncommon and typically nosocomial in origin.
Aim: This study was done to estimate the prevalence of Vancomycin-resistant Enterococcal meningitis and to assess the risk factors amongst these patients. Also resistance pattern of these Vancomycin resistant Enterococcal isolates towards other antibiotics were also assessed.
Materials and methods: This observational analysis was done in the Microbiology department of a tertiary care referral center from January 2021 to July 2023. Cerebrospinal fluid (CSF) samples of all cases of suspected meningitis were included in the study and sent to Microbiology lab for culture and sensitivity. Culture was done on chocolate agar 5% blood agar and MacConkey agar and incubated aerobically for 72 hours. After incubation the isolate was identified by MALDI-ToF MS. Sensitivity was done using Kirby Bauer disk diffusion method and interpreted using CLSI 2023 M-100 clinical breakpoints. The patients’ demographic details associated risk factors type of surgery done and the clinical outcome of the patients were analyzed.
Statistical analysis: Clinical data and values were entered in Excel sheet. Univariate analysis of the risk factors was done and p-values <0.05 were considered significant.
Results: A total of 2352 CSF samples were cultured of which 292 (12.4%) samples showed growth on culture. Enterococcus species were isolated in 30 (10.3%) samples. The predominant species was Enterococcus faecalis (n=17; 56.7%). Majority of the patients presented with fever (50%) and headache (33.3%). The risk factors in these patients were hypertension (40%) and diabetes mellitus (33.3%). All the patients had an extra-ventricular drain (EVD) present in them. Intracranial surgery was done in 15 patients. Only 1 (3.3%) patient died due to enterococcal meningitis. Of these 6 (20%) isolates were Vancomycin resistant. Statistically significant risk factors in these patients were hypertension prolonged hospital stay of >21 days. Majority of the isolates were resistant to Levofloxacin high level gentamicin doxycycline and ampicillin. Removal of the EVD helped in better prognosis of the patients
Conclusion: Early detection is crucial for a positive clinical result since vancomycin resistant enterococcal meningitis is associated with a high morbidity rate.
Interaction with refuse piles drives co-occurrence of core gut microbiota in workers of the ant Aphaenogaster picea
Comparing the diversity of gut microbiota between and within social insect colonies can illustrate interactions between bacterial community composition and host behavior. In many eusocial insect species different workers exhibit different task behaviors. Thus these workers may benefit from symbiotic relationships with certain bacteria that augment the metabolic processes underlying their specific behaviors. Evidence of compositional differences between core microbiota in different worker types could suggest a microbial association with division of labor among workers. Here we present the core microbiota of Aphaenogaster picea ant workers with different task behaviors. The genus Aphaenogaster is abundant worldwide yet the associated microbiota of this group is unstudied. Bacterial communities from A. picea gut samples in this study consist of 19 phyla dominated by Proteobacteria Cyanobacteria and Firmicutes. Analysis of 16S rRNA gene sequences reveals distinct similarity clustering of A. picea gut bacterial communities in workers that have more interactions with the refuse piles. Though gut bacterial communities of nurse and foraging ants are similar in overall composition and structure the worker groups differ in relative abundances of dominant taxa. Interaction with fecal matter via refuse piles seems to have the greatest impact on taxa distribution and this effect appears to be independent of worker type. This is the first report surveying the gut microbiome community composition of Aphaenogaster ants.
An atypical case of esophageal actinobacillosis in a cow
Present case report describes an unusual instance of esophageal actinobacillosis in an adult cow presented to the university hospital with a history of inability to drink and swallow. Clinical evaluation revealed a noticeable five-inch swelling in the Juglar groove while radiographic imaging indicated the presence of a small round and mildly radio-opaque lesion. In response an exploratory surgical excision was performed as a palliative measure and the excised tissue was subsequently preserved in 10% buffered formalin for histopathological examination. Histopathology revealed pyogranulomatous inflammation characterized by radiating eosinophilic club shaped bodies surrounding small colonies of coccobacilli. Grams and Zeil Neelson stains confirmed the presence of gram negative and non-acid fast coccobacilli. Additionally following a thorough review of relevant literature on atypical actinobacillosis the authors assert the rarity of esophageal involvement with this case representing only the second documented instance globally.
Comparative analysis of virulence gene profiles of Escherichia coli from clinical and non-clinical sources in Rivers State, Nigeria
Traditionally the presence of virulence features have been thought to be a key factor in differentiating pathogenic from commensal strains. An understanding of virulence potential of Escherichia coli isolates from various sources is essential to help shed light on potential contamination/transmission rates between the various sources. This study was therefore aimed at exploring the occurrence of specific virulence genes and gene profiles associated with Escherichia coli from clinical and non-clinical sources in Rivers State Nigeria.
Two hundred samples from clinical (urine and feces) and non-clinical (soil and poultry droppings) sources (50 each) were analyzed using standard microbiological procedures. DNA was extracted from isolates presumptively identified as Escherichia coli using PrestoTM Mini gDNA Bacteria-Kit Quick protocol following the manufacturer’s instructions. Isolate identities were confirmed using E. coli specific 16S rRNA primers and confirmed isolates screened for the presence of six virulence genes (Afimbriae binding adhesin (afa) type 1 fimbriae (fimH) P-fimbrial Usher Protein (papC)) iron acquisition systems: aerobactin (aer) Cytotoxic necrotizing factor I (cnf1) and alpha hemolysin (hly).
Results showed that all isolates haboured at least one of the tested virulence genes with fimH (97%) as the most prevalent virulence gene and papC the least commonly occurring (35%). A higher occurrence of virulence genes was noted in non-clinical isolates though hly and cnf were not detected at all in any of the isolates studied (0%). Ten different profiles were observed with the afaCc-aer-fimH profile the most commonly occurring virulence gene profile in general (33.3%). For non-clinical isolates however the aer-afaCc-fimH-papC was the most commonly occurring profile (42.9%).
This study shows that the test Escherichia coli from clinical and non-clinical sources do not carry distinct virulence gene profiles. Studies on a larger subset of isolates would however be necessary to determine if indeed the virulence genes tested for in this study really cannot be used to tell whether an isolate is from a clinical source or not in the South-South of Nigeria.
Variability of pMGA/vlhA sequences among Mycoplasma gallisepticum field strains isolated from laying hens and their deformed eggs.
Mycoplasmosis attributed to Mycoplasma gallisepticum poses a significant challenge to poultry farming leading to substantial economic losses and persistent infections within flocks. This bacterium harbors various surface proteins that are crucial for the adhesion transporter activity and evasion of the host immune response facilitating its pathogenicity. One such key surface lipoprotein referred to as pMGA or vlhA hemagglutinin plays a pivotal role in adhesion processes. In this study the clonal regions pMGA1.2 and pMGA1.3 as reported by Markham (M83178.1) were investigated to elucidate differences or similarities in the whole DNA sequences of Myc. gallisepticum field strains. The aim was to analyze sequence diversity within this region. Six internal primers were designed to amplify the target sequence and isolates were obtained from both eggs and chickens sourced from laying hen flocks. Identification revealed 17 strains of Myc. gallisepticum and four strains of Myc. synoviae which were confirmed through the mgc2 and 16S rRNA genes respectively. Positive and negative controls were established using the MGS6 and MSWUV1853 strains. Amplification results indicated a higher frequency of amplification proximal to the C-terminal region with segments 4 (33.3%) and 6 (27.8%) being the most prevalent. Notably none of the field strains exhibited the same amplification pattern as MGS6 and none of the strains characterized as Myc. synoviae amplified any primer set.
Upon translation the amino acid sequences from segments 4 and 6 were found to be compatible with conserved sequences within the Myco_haema protein domains of the genus Mycoplasma specifically corresponding to Q7NAP3_MYCGA VlhA.3.04. The observed homology suggests a potential genetic transfer while the variability identified in the pMGA or vlhA gene region of the field strains may have significant implications for protection against Myc. gallisepticum infection in chickens.
Exceptional association of two species of bacteria causing acute appendicitis: Haemophilus influenzae and Enterobacter cloacae
Appendicitis typically caused by appendiceal lumen obstruction is a prevalent abdominal surgical emergency worldwide. While most cases involve Enterobacterales Haemophilus influenzae primarily known for upper respiratory infections is infrequently associated with gastrointestinal infections. This article presents an exceptional case of acute appendicitis caused by both Haemophilus influenza and Enterobacter cloacae in a 15-year-old child highlighting the significance of recognizing uncommon pathogens in appendicitis and emphasizing the necessity for thorough microbiological investigations to refine diagnostic approaches.
Genome sequencing and analysis of Salmonella enterica subsp. enterica serotype Enteritidis PT4 578
Salmonella enterica serotype Enteritidis is a generalist serotype that adapts to different hosts and transmission niches. It has significant epidemiological relevance and is among the most prevalent serotypes distributed in several countries. Salmonella Enteritidis causes self-limited gastroenteritis in humans which can progress to systemic infection in immunocompromised individuals. Poultry products are considered significant reservoirs of many Salmonella serotypes and Salmonella Enteritidis infections are often related to the consumption of chicken meat and eggs. This study reports the whole-genome sequence of Salmonella Enteritidis PT4 strain 578. A total of 165 genes (3.66%) of the 4506 coding sequences (CDS) predicted in its genome are virulence factors associated with cell invasion intestinal colonization and intracellular survival. The genome harbors twelve Salmonella pathogenicity islands (SPIs) with the SPI-1 and SPI-2 genes encoding type III secretion systems (T3SS) showing high conservation. Six prophage-related sequences were found with regions of intact prophages corresponding to Salmon_118970_sal3 and Gifsy-2. The genome also contains two CRISPR systems. Comparative genome analysis with three other serotypes of Salmonella demonstrates that most unshared genes are related to metabolism membrane and hypothetical proteins. Finally the phenotypic characterization evidenced differences among Salmonella Enteritidis PT4 578 and the other three serotypes regarding the expression of the red dry and rough (rdar) morphotype and biofilm formation. Overall the genomic characterization and phenotypic properties expand knowledge of the mechanisms of pathogenicity in Salmonella Enteritidis PT4 578.
Brief Report: Nasal colonization with Staphylococcus aureus and Methicillin resistant Staphylococcus aureus among community-dwelling older adults with comorbidities seeking follow-up medical care in Central Sri Lanka.
Older adults are more severely affected by infections caused by drug-resistant bacteria including Methicillin-Resistant Staphylococcus aureus (MRSA). We aimed to identify the MRSA colonization rates and associated factors among older adults aged more than 65-years-old. Among the 309 recruited 152 (49.2%) were males. Self-collected nasal swabs were used to isolate Staphylococcus aureus and MRSA with routine microbiological methods. Staphylococcus aureus was isolated from 36 (11.7%) participants while 11 (3.6%) were colonized with MRSA. We identified a significant association between the male sex and MRSA colonization (p=0.028 Chi-square test). However this needs careful interpretation given the smaller number of outcome events. Other factors studied had no statistically significant association with MRSA colonization.
HIV combined with skin infection of Nocardia brasiliensis: A rare case report
Introduction. The HIV virus can attack and gradually damage the human immune system causing the host to be unprotected when infected. Nocardia is a type of opportunistic pathogenic bacteria that can easily cause infections in patients with chronic wasting diseases immune dysfunction and the use of immunosuppressants. Nocardia can invade various tissues and parts of the body causing corresponding clinical symptoms. There are few reports of HIV patients being infected with Brazilian Nocardia.
Case presentation. This article reports a case of an HIV patient with concurrent infection with Brazilian Nocardia. A patient with HIV developed a lump on the surface of their left skin without any obvious cause. Due to improper disinfection and treatment methods the condition worsened and they subsequently sought medical attention at our hospital. A series of laboratory related tests are conducted clinically based on the patient's medical history symptoms and signs. Based on the test results a reasonable treatment plan was adopted clinically ultimately achieving satisfactory treatment outcomes for patients.
Conclusion. HIV patients are prone to various types of infections even rare bacteria as their immune function decreases. With the popularity of new identification methods such as mass spectrometry laboratories should pay attention to traditional staining methods and use microscopes to detect pathogens.
Exploration and characterization of a newly isolated bacterium, Enterobacter quasihormaechei strain BDIFST24001, capable of producing rhamnolipids biosurfactant for oil remediation
Biosurfactants are naturally occurring compounds synthesized by microorganisms that increasingly attract attention due to both their living area and application in various industries. In this study we explore and characterize a novel bacterium Enterobacter quasihormaechei strain BDIFST24001 isolated for its ability to produce rhamnolipids biosurfactants with the aim of facilitating oil remediation processes. The isolation of this bacterium was carried out using Luria-Bertani broth (LB) media from environmental samples collected from oil-contaminated sites in Dhaka city. Screening tests including the oil spreading method and drop collapse assay were conducted to identify potential biosurfactant-producing strains leading to the selection of E. quasihormaechei strain BDIFST24001 based on its favorable performance. Subsequent molecular identification revealed a high similarity of the strain's 16S rRNA gene to E. quasihormaechei which was corroborated through phylogenetic analysis. Further analysis of the biosurfactant produced by this strain indicated its rhamnolipids nature as confirmed by FT-IR spectroscopy. The rhamnolipids exhibited promising surface-active properties including a significant reduction in surface tension and emulsification activity as evidenced by surface tension measurements and emulsification index assays. Optimization studies revealed that the optimal conditions for rhamnolipids production by E. quasihormaechei strain BDIFST24001 were a temperature of 37°C pH 10.0 and salinity of 4%. The rhamnolipids produced by this strain demonstrated effective oil remediation capabilities as observed through controlled experiments using petrol oil. The rhamnolipids effectively reduced the surface tension of the oil-water interface facilitating the dispersion and emulsification of the oil phase in water. Overall our findings highlight the potential of E. quasihormaechei strain BDIFST24001 as a promising candidate for biosurfactant-mediated oil spill cleanup and environmental remediation efforts.
Human Metapneumovirus (hMPV): An associated etiology of Severe Acute Respiratory Infection in Children of Eastern Uttar Pradesh, India.
Acute respiratory infections (ARIs) are a serious public health concern across the world causing considerable morbidity and mortality. Every year around 13 million children under the age of five die. Approximately 95% of them are from developing nations and ARIs are responsible for one-third of all deaths. Human Metapneumovirus (hMPV) is one of the causative agents associated with respiratory tract infections. There is lack of information about hMPV from the eastern region of Uttar Pradesh. In our centre Indian Council of Medical Research- Regional Medical Research Centre Gorakhpur (ICMR‐RMRC Gorakhpur) at Gorakhpur Uttar Pradesh India; we tested for respiratory pathogens in under-five patients presenting with ARI and severe acute respiratory illness (SARI) through semi nested PCR. A total of 100 nasal and throat specimens were collected from the OPD and IPD of Department of Paediatrics BRD Medical College Gorakhpur during from February 2022 to April 2022. Out of 100 enrolled pediatric patients 4 (4%) were found to be positive. Among the patients who tested positive for hMPV 25% (1/4) patient unfortunately died. The phylogenetic analysis of hMPV showed the close resemblance with the clade of Singapore and USA hMPV isolates. Our work underlines the importance of hMPV as the cause of acute respiratory infections in children and the need for routine testing for this virus in laboratories. Further comprehensive information regarding the incidence of hMPV in this area is needed.
Title of Manuscript: Prevalence of SARS- CoV-2 virus in saliva, stool, and urine samples of COVID-19 patients in Bihar, India
Introduction: The coronavirus illness caused by SARS- CoV-2 can cause multiple organ involvement with varying degrees of severity. Besides inhalation as a route for transmission feco-oral has also been proposed. Its transmission to sewage systems is a growing public health issue.
Objective: To detect SARS-CoV-2 RNA in non-respiratory samples (saliva urine and stool) collected from COVID-19 cases in Bihar.
Materials and methods: This Cross-Sectional observational study was conducted from January 2021 to March 2022 on human non-respiratory samples. A total of 345 samples including saliva (116) stool (97) and urine (132) were collected from 143 covid-19 cases. Samples were analyzed for SARS-CoV-2 by multiplex RT-PCR targeted against E ORF 1ab and RdRp gene.
Results: In this study out of 143 cases a total of 107(74.8%) were positive for SARS-CoV-2 RNA in at least one of the non-respiratory samples.
Conclusion: There is a high prevalence of SARS-CoV-2 virus in non-respiratory samples.
Deciphering the interaction surface between the West Nile virus NS3 and NS5 proteins
West Nile virus (WNV) is the most prevalent mosquito-borne disease and the leading cause of viral encephalitis in the continental United States. It belongs to the Flavivirus family which includes other important human pathogens such as dengue virus (DENV) Japanese encephalitis virus (JEV) and Zika viruses (ZIKV). Despite several decades of research no specific antiviral drugs are available to treat Flavivirus infections. The present study characterizes the interaction between the WNV NS3 and NS5 proteins for the purpose of identifying hotspots in the protein-protein interaction which could be targeted for the development of antiviral therapeutics. We previously developed an interaction model in silico based on data available in the literature. Here potential interacting residues on NS3 and NS5 were mutated in a WNV replicon and seven mutations in the NS3 protein were found to drastically reduce viral replication. In addition to being well conserved among mosquito-borne Flaviviruses these residues are located on the protein’s surface in two clusters which might be interesting new targets for future drug development.
Development of Recombinant Proteins for Vaccine Candidates Against Serotype O and A of Foot and Mouth Disease Virus in Bangladesh
Frequent vaccine failure leading to recurrent outbreaks of Foot-and-Mouth Disease (FMD) in livestock populations necessitates the development of a customizable vaccine platform comprising potential antigenic determinants of circulating lineages of FMD viruses. Artificially designed chimeric peptide-based recombinant vaccines are novel approaches to combat the phylogenetically diverse FMD Virus (FMDV) strains. Among seven recognized serotypes only serotypes O and A are dominantly circulating in Bangladesh and neighboring countries of Asia where transboundary transmission recurrent outbreaks and emergence of novel lineages of FMDV are highly prevalent. The objective of this study was to develop multi-epitope recombinant peptides procuring immunogenicity against circulating diverse genotypes of FMDV serotypes O and A. Two chimeric peptides named B1 (41.0 kDa) and B3 (39.3 kDa) have been designed to incorporate potential B-cell and T-cell epitopes selected from multiple FMDV strains including previously reported and newly emerged sub-lineages. After expression characterization and immunization of guineapigs with considerable antigen load of B1 and B3 followed by the serological assays revealed the significant protective immunogenicity developed from the higher (100 µg) doses of both antigens against most of the currently prevalent serotype O and A strains of FMDV. The efficient expression antigenic stability and multivalent immunogenic potency of the chimeric peptides strongly indicate their credibility as novel vaccine candidates for existing serotypes O and A of FMDV in Bangladesh and surrounding territories.
An Evaluation of ChatGPT and Bard (Gemini) in the Context of Biological Knowledge Retrieval
ChatGPT and Bard (now called Gemini) two conversational AI models developed by OpenAI and Google AI respectively have garnered considerable attention for their ability to engage in natural language conversations and perform various language-related tasks. While the versatility of these chatbots in generating text and simulating human-like conversations is undeniable we wanted to evaluate their effectiveness in retrieving biological knowledge for curation and research purposes. To do so we asked each chatbot a series of questions and scored their answers based on their quality. Out of a maximal score of 24 ChatGPT scored 5 and Bard scored 13. The encountered issues included missing information incorrect answers and instances where responses combine accurate and inaccurate details. Notably both tools tend to fabricate references to scientific papers undermining their usability.
In light of these findings we recommend that biologists continue to rely on traditional sources while periodically assessing the reliability of ChatGPT and Bard. As ChatGPT aptly suggested for specific and up-to-date scientific information established scientific journals databases and subject-matter experts remain the preferred avenues for trustworthy data.
Enhancement of growth media for extreme iron-limitation in Escherichia coli
Iron is an essential nutrient for microbial growth and bacteria have evolved numerous routes to solubilise and scavenge this biometal which is often present at very low concentrations in host tissue. We recently used a MOPS-based medium to induce iron limitation in Escherichia coli K-12 during the characterisation of novel siderophore conjugated antibiotics. In this study we confirm that growth media derived from commercially-available M9 salts are unsuitable for studies of iron-limited growth likely through the contamination of the sodium phosphate buffer components with over 100 µM iron. In contrast MOPS-based media that are treated with metal-binding Chelex® resin allow the free iron concentration to be reduced to growth-limiting levels. Despite these measures a small amount of E. coli growth is still observed in these iron-depleted media. By growing E. coli in conditions that theoretically increase the demand for iron-dependent enzymes namely by replacing the glucose carbon source for acetate and by switching to a microaerobic atmosphere we can reduce background growth even further. Finally we demonstrate that by adding an exogeneous siderophore to the growth media which is poorly used by E. coli we can completely prevent growth perhaps mimicking situation in host tissue. In conclusion this short study provides practical experimental insight into low iron media and how to augment the growth conditions of E. coli for extreme iron-limited growth.
Genome sequence of the plant-growth-promoting bacterium Bacillus velezensis EU07
Many Gram-positive spore-forming rhizobacteria of the genus Bacillus show potential as biocontrol biopesticides that promise improved sustainability and ecological safety in agriculture. Here we present a draft-quality genome sequence for Bacillus velezensis EU07 which shows growth-promotion in tomato plants and biocontrol against Fusarium head blight. We found that the genome of EU07 is almost identical to that of the commercially used strain QST713 but identified 46 single-nucleotide differences that distinguish these strains from each other. The availability of this genome sequence will facilitate future efforts to unravel the genetic and molecular basis for its beneficial properties.
PATHOGENECITY AND ENZYME SCREENING OF SOME SELECTED NON-DERMATOPHYTIC MOLDS
A total of 10 non-dermatophytic molds isolated from both symptomatic and asymptomatic cattle skin which includes Penicillum citrinum Aspergillus welwitschiae Aspergillus aculeatus Curvularia kusanol Cladosporium teniussmum Pestalotiopsis microspora Fusarium oxysporum Fusarium linchenicola Absidia sp. and Aspergillus fumigatuswere subjected to a pathogenicity test using albino mice. These isolates were also screened for five enzymes using standard plate method. Result from pathogenicity test showed that Absidia sp C. tenuissimum and Aspergillus welwitschiae were able to elicit discoloration lesion production and alopecia on the albino mice skin respectively which are evidences of clinical symptoms associated of cutaneous mycoses. The enzyme screening results revealed the highest zone of activity for keratinase (65mm) amylase (86mm) protease (60mm) lipase (60mm) and cellulase (86mm) which were observed on P. microspora A. welwitschiae C. tenuissimum A. welwitschiae and A. welwitschiae respectively. Pathogenicity test from this study shows that some of these molds may be virulent and that can be attributed to their ability to possess some virulent factors which includes secretion of hydrolytic enzymes.
Detection and significance of anti-Mycobacterium tuberculosis specific IgG antibody response for the diagnosis of pulmonary tuberculosis using enzyme-linked immunosorbent assay
Objective: Evaluation of an ELISA test for detection of IgG antibody response using in-house prepared Mycobacterium tuberculosis H37Rv soluble extract (MTSE) as antigen for rapid diagnosis of pulmonary tuberculosis and its clinical usefulness.
Methods: In this study a total of 758 pulmonary tuberculosis (TB) patients (652 AFB-positive and 106 AFB-negative) 276 healthy controls and 43 pulmonary infectious disease controls other than TB were recruited. IgG antibody level against MTB soluble extract was measured in sera samples of all study groups using an ELISA test. The level of IgG antibody responses was compared among groups by the Kruskal-Wallis test. The pairwise comparison was made by the Mann-Whitney test A positive score was represented by optical density above the cut–off value which was calculated from OD values of healthy controls by adding 2SD to the mean OD value. The evaluation of diagnostic value was considered based on sensitivity and specificity.
Results: Significantly higher levels of IgG antibody response were observed in PTB patients compared to healthy control and non-TB other pulmonary infectious disease control groups (p value<0.0001). The percent positivity for the IgG antibody response was higher in AFB-positive 574/652 (88.04%) and 79/106 (74.53%) AFB-negative PTB patients as compared to healthy control 9/276 (3.26%) and non-TB other pulmonary infectious disease control 3/43 (6.97%). The sensitivity of the test in PTB patients (AFB-positive and AFB-negative) was 86.15% (95% CI; 83.48-88.53) and the specificity was 96.74% (95% CI; 93.90-98.50).
Conclusion: This developed immunological test could be an efficient test in detecting IgG antibody response in PTB patients. Further this test could be useful for diagnosing AFB-negative presumptive TB cases.