Draft genome sequence of Staphylococcus gallinarum BAU_KME002 strain isolated from egg surface in Bangladesh.

This report describes the genome sequence of the Staphylococcus gallinarum BAU_KME002 strain isolated in Bangladesh in 2021 from a chicken egg surface. Our assembled genome had 50 contigs, an estimated genome length of 2,866,882 bp (with coverage of 90.0×), 36 predicted antibiotic resistance genes, and 28 predicted virulence factor genes.

Bacteriological quality and prevalence of foodborne bacteria in broiler meat sold at live bird markets at Mymensingh City in Bangladesh.

Objective: This study assessed the bacteriological quality and prevalence of foodborne bacteria in raw broiler meat sold in Mymensingh City. Materials and Methods: Thigh and breast meat samples (n = 80) from broiler chickens were randomly collected from four live bird markets (LBM) in Mymensingh city for bacteriological analysis. To determine the bacteriological quality, a 10-fold serial dilution of the thigh and breast homogenate was made. Then, total viable count (TVC), total coliform count (TCC), Staphylococci, and Salmonella spp. counts were determined using plate count agar, MacConkey agar, Mannitol salt agar, and Salmonella-Shigella agar. Gram stain, biochemical testing, PCR assays, and cultural properties were used to identify the bacterial isolates. Results: The TVC in the broiler meat sample ranged between log10 8.30 ± 0.54 colony forming unit (CFU)/gm and log10 9.04 ± 0.26 CFU/gm. TCC was found between log10 5.53 ± 0.38 CFU/gm and log10 6.66 ± 0.80 CFU/gm. The mean Staphylococcal count was recorded between log10 4.64 ± 0.61 CFU/gm and log10 6.42 ± 0.53 CFU/gm, and the total Salmonella count ranged between log10 4.75 ± 0.08 CFU/gm and log10 5.69 ± 0.58 CFU/gm. The prevalence of Escherichia coli was the highest (43.2%), followed by Staphylococcus aureus (36.8%) and Salmonella spp. (20%), respectively. Conclusions: Data from this study indicated that the TVC and TCC of raw broiler meat sold at LBM exceed the permissible limits and are contaminated with foodborne bacteria, which might cause public health hazards.

Virulence Determinants and Methicillin Resistance in Biofilm-Forming Staphylococcus aureus from Various Food Sources in Bangladesh.

The eradication of staphylococcal infections has become more difficult due to the development of antibiotic resistance and virulence in biofilm-forming Staphylococcus aureus. The presence of the life-threatening zoonotic pathogen, methicillin-resistant S. aureus (MRSA), in foods indicates a public health issue. This study, therefore, aimed to determine virulence factors and methicillin resistance in biofilm-forming S. aureus isolates from different foods and food handlers. A total of 100 PCR-positive S. aureus isolates (97 biofilm formers and three non-biofilm formers) were screened using the disk diffusion method and PCR assay. By PCR, genes encoding virulence factors, e.g., enterotoxin (sea, 30%, 95% CI: 21.90−39.59%), toxic shock syndrome toxin (tst, 20%, 95% CI: 13.34−28.88%), and Panton−Valentine leukocidin toxin (PVL, 15%, 95% CI: 9.31−23.28%), were detected in the S. aureus isolates. By the disk diffusion method, 100% (95% CI: 96.30−100.00%) of S. aureus isolates were phenotypically MRSA in nature, showing 100% resistance to oxacillin and cefoxitin. Moreover, the methicillin-resistant gene mecA was found in 61 (61%, 95% CI: 51.20−69.98%) MRSA isolates. Furthermore, all the S. aureus isolates were phenotypically resistant to ampicillin and penicillin, 30% to erythromycin, and 11% to gentamycin. Among them, 51% (95% CI: 41.35−60.58%) of S. aureus isolates were phenotypically multidrug-resistant in nature, and the multiple antibiotic resistance index varied from 0.33 to 0.55. Genes encoding resistance to beta-lactams (blaZ, 100%, 95% CI: 96.30−100.00%) and tetracyclines (tetA and tetC, 3%, 95% CI: 0.82−8.45%) were found positive in the S. aureus isolates. Genes encoding virulence determinants and MRSA were significantly (p < 0.05) higher in strong biofilm-forming S. aureus than in moderate and non-biofilm-forming isolates. To our knowledge, this is the first study in Bangladesh to incorporate preliminary data on the occurrence of virulence determinants and methicillin resistance, including resistance to clinically important antibiotics, in biofilm-forming S. aureus isolates from different foods and food handlers in Bangladesh, emphasizing a potential threat to human health.

Phenotypic and Genotypic Detection of Biofilm-Forming Staphylococcus aureus from Different Food Sources in Bangladesh.

Staphylococcus aureus is a major foodborne pathogen. The ability of S. aureus to produce biofilm is a significant virulence factor, triggering its persistence in hostile environments. In this study, we screened a total of 420 different food samples and human hand swabs to detect S. aureus and to determine their biofilm formation ability. Samples analyzed were meat, milk, eggs, fish, fast foods, and hand swabs. S. aureus were detected by culturing, staining, biochemical, and PCR. Biofilm formation ability was determined by Congo Red Agar (CRA) plate and Crystal Violet Microtiter Plate (CVMP) tests. The icaA, icaB, icaC, icaD, and bap genes involved in the synthesis of biofilm-forming intracellular adhesion compounds were detected by PCR. About 23.81% (100/420; 95% CI: 14.17−29.98%) of the samples harbored S. aureus, as revealed by detection of the nuc gene. The CRA plate test revealed 20% of S. aureus isolates as strong biofilm producers and 69% and 11% as intermediate and non-biofilm producers, respectively. By the CVMP staining method, 20%, 77%, and 3% of the isolates were found to be strong, intermediate, and non-biofilm producers. Furthermore, 21% of S. aureus isolates carried at least one biofilm-forming gene, where icaA, icaB, icaC, icaD, and bap genes were detected in 15%, 20%, 7%, 20%, and 10% of the S. aureus isolates, respectively. Bivariate analysis showed highly significant correlations (p < 0.001) between any of the two adhesion genes of S. aureus isolates. To the best of our knowledge, this is the first study in Bangladesh describing the detection of biofilm-forming S. aureus from foods and hand swabs using molecular-based evidence. Our findings suggest that food samples should be deemed a potential reservoir of biofilm-forming S. aureus, which indicates a potential public health significance.

Isolation, identification, and antibiogram studies of Escherichia coli from ready-to-eat foods in Mymensingh, Bangladesh.

Background and Aim: Ready-to-eat (RTE) foods are widely used at home, restaurants, and during festivals in Bangladesh. So it is very important to investigate possible microbial contamination in RTE foods. Therefore, this study aimed to determine the total coliform count (TCC), isolate, identify, and characterize the Escherichia coli in RTE foods. The antimicrobial sensitivity of E. coli obtained from RTE foods was also performed using 12 commonly used antibiotics. Materials and Methods: A total of 100 RTE food samples were collected aseptically and comprised of ten samples each: Burger, pizza, sandwich, chicken roll, chicken meat loaf, chicken fry, salad vegetable, ice-cream, yogurt, and milkshake sold in Mymensingh City. Samples were inoculated onto Eosin methylene blue agar and incubated at 37°C for 24 h. Isolation and identification of bacteria were performed based on cultural, staining, and biochemical properties, followed by a polymerase chain reaction. Results: The TCC in Chicken meat loaf, burger, pizza, sandwich, salad vegetable ice-cream, and yogurt samples were 3.57 ± 0.96, 3.69 ± 0.08, 3.50 ± 0.60, 2.60 ± 0.20, 4.09 ± 0.29, 4.44 ± 0.25, and 3.14 ± 0.30 mean log colony-forming units ± standard deviation/mL, respectively. The study found a higher prevalence of E. coli in RTE salad vegetable products than in RTE meat and milk products. Forty percent of the mixed vegetable salad samples showed positive results for E. coli. Whereas E. coli prevalence in RTE meat and milk products was 20% and 16.7%, respectively. All the 21 isolates were subjected to antibiotic susceptibility test against 12 different antibiotics. It was observed that 46.1% were susceptible, 16.6% were intermediate, 46.1% were resistant, and 47.6% were multidrug-resistant (MDR) among seven different antibiotic classes. E. coli isolates were resistant to cephalexin, ceftazidime, oxytetracycline, and ampicillin and sensitive to gentamycin, followed by kanamycin, ceftriaxone, colistin, and enrofloxacin. Conclusion: The study revealed that RTE foods are a serious issue from a public health point of view. To achieve a safer level of E. coli in RTE foods sold for human consumption, public food outlets must improve hygienic and good production procedures. Moreover, MDR E. coli in these foods pose serious public health threats.

Multidrug-resistant Staphylococcus aureus isolated from chicken nuggets sold at superstores in Mymensingh, Bangladesh.

Objective: This study was conducted to determine the colony forming units (CFU) to isolate, identify, and antibiotic sensitivity of Staphylococcus aureus from chicken nuggets (CN). Materials and Methods: Sixty CN samples from two brands were collected from different superstores in Mymensingh, Bangladesh. Uncooked, oven-cooked (OC), or gas stove-cooked (GSC) CN samples were inoculated onto mannitol salt agar and blood agar. Results: The total staphylococcal count (TSC) for uncooked CN ranged from log 4.68 to log 5.11 CFU/gm. For OC CN, TSC ranged from log 3.29 to log 3.62 CFU/gm. For GSC CN, TSC ranged from log 3.09 to log 3.49 CFU/gm. Relative to uncooked CN, microwave oven-cooked and GSC samples significantly reduced the TSC of CN (p < 0.01). Using the polymerase chain reaction assay and standard biochemical testing, only 8 out of 60 CN samples contained S. aureus. Staphylococcus aureus were resistant to Ampicillin (100%), Amoxicillin (100%), Oxacillin (75%), Cefixime (87.5%), Doxycycline (75%), intermediately sensitive to Erythromycin (25%), Cephalexin (12.5%), Ciprofloxacin (25%), Gentamicin (12.5%), Doxycycline (12.5%) and sensitive to Oxacillin (25%), Azithromycin (100%), Erythromycin (75%) Cephalexin (87.5%), Cefixime (12.5%), Chloramphenicol (100%), Ciprofloxacin (75%), Gentamicin (87.5%), Doxycycline (12.5%), and Vancomycin (100%). Conclusion: This study reports the first isolation and identification of S. aureus from CN in Bangladesh. GSC CN was better than OC and uncooked CN. Data also suggest that CN is contaminated with multidrug-resistant S. aureus, which poses a public health hazard.

In Vitro and In Vivo IFN-γ and IL-10 Measurement in Experimental Brucella abortus Biotype 1 Infection in Sprague-Dawley Rats.

The immune response to Brucella abortus mainly depends on antigen-specific T cell activation, CD4+ and CD8+ T cells, and Brucella-specific humoral response. Protective immune response against Brucella infection has not been performed in the Sprague-Dawley (SD) rat model. We measured bacterial kinetics in addition to in vivo and in vitro interferon gamma (IFN-γ) and interleukin-10 (IL-10) production against crude Brucella protein in the SD rats at different days of postinfection with B. abortus biotype 1 by indirect enzyme-linked immunosorbent assay. Forty SD rats were inoculated intraperitoneally with 0.1 mL sterile injectable pyrogen-free solution containing 1 × 1010 colony-forming units/mL of B. abortus biotype 1 obtained from cattle in Korea. Four rats were used as uninfected control. Serum IFN-γ level at 3 and 7 days postinfection were significantly higher (p > 0.001) compared with the IL-10 level. On the contrary, serum IL-10 levels were observed significantly higher at 21 and 28 days postinfection compared with the serum IFN-γ levels (p < 0.001). The production of IFN-γ by spleen cells was significantly higher at 7 and 14 days postinfection compared with IL-10 (p < 0.001). On the contrary, IL-10 productions were found to be significantly higher at 21, 28, 35, and 42 days postinfection compared with IFN-γ (p < 0.001). The presence of B. abortus in blood was marked till 5 weeks of infection, throughout the experiment in case of spleen, and no bacteria were isolated from the kidney and liver at 6 weeks postinfection. The in vivo and in vitro IFN-γ and IL-10 measurement in our study reported that B. abortus infection in rats primarily educe T helper (Th)1-dominant immune response in acute infection accompanied by Th2-dominant immune response in chronic infection.

Extract of neem (Azadirachta indica) leaf exhibits bactericidal effect against multidrug resistant pathogenic bacteria of poultry.

The aim of the study was to determine the efficacy of neem leaf extract against multidrug resistant (MDR) pathogenic bacteria. Laboratory stock culture of Pasteurella multocida, Salmonella pullorum, Salmonella gallinarum and Escherichia coli was revived. Antibiogram profiles of these bacteria were determined by disc diffusion method. Ethanolic extract of neem leaf was prepared. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of neem leaf extract (112.5, 100, 50, 25, 12.5, 6.25 and 3.12 mg/ml) against MDR pathogenic bacteria of poultry were determined by double dilution method. The MIC and MBC of the neem leaf extract were 12.5 and 25 mg/ml, respectively for P. multocida, 50 and 100 mg/ml for S. pullorum and S. gallinarum, 100 and 112.5 mg/ml for E. coli. Neem leaf extracts exhibited bactericidal effect against MDR pathogenic bacteria of poultry.

Duck virus enteritis (duck plague) outbreak in an Australian black swan (Cygnus atratus) flock at safari park in Bangladesh: A case report.

OBJECTIVE: Duck virus enteritis is a severe viral disease that kills ducks and swans worldwide. The clinical manifestations, gross pathology, molecular detection, and characterization of the duck virus enteritis virus (DVEV) in Australian black swans at a safari park in Bangladesh were described in this case report. MATERIALS AND METHODS: On a safari park in Bangladesh, an Australian black swan flock exhibited clinical signs of anorexia, greenish watery diarrhea, increased thirst, partial paralysis, and death. Postmortem examinations of deceased swans revealed extensive pathological abnormalities in the trachea, liver, and spleen. To isolate DVEV, a viral inoculum produced from the liver and spleen of dead swans was implanted into 9-13-day-old embryonated duck eggs via the chorioallantoic membrane (CAM) route. DVEV was confirmed using a polymerase chain reaction (PCR) assay. Phylogenetic analysis was used to determine the genetic relationship between the DVEV isolates from Australian black swans, and 16 DVEV isolates previously described in the GenBank. RESULTS: Hemorrhage was noted in the annular ring of the trachea, as well as an enlarged and hemorrhagic liver and spleen. The PCR assay amplified a 446-bp fragment of the DVEV DNA polymerase gene in the liver, spleen, and CAM homogenates. The phylogenetic analysis found that the DVEV isolates from swans were comparable to those from Bangladesh, India, Vietnam, China, Germany, the USA, and Egypt. CONCLUSION: According to the findings of this study, the DVEV was the cause of illness and mortality in an Australian black swan flock.

The Profile of Immunoglobulin A and Immunoglobulin G Subclasses in Sprague Dawley Rats Experimentally Infected with Brucella abortus Biotype 1.

This study measured total serum immunoglobulin A (IgA), immunoglobulin G (IgG)1, IgG2a response against whole cell antigen (WCA), outer membrane protein (OMP), periplasmic protein (PP), cytoplasmic protein (CP), and crude Brucella protein (CBP) of Brucella abortus in experimental brucellosis induced with B. abortus biotype 1 in Sprague Dawley (SD) rats during a 17-week infection period. Six- to 8-week-old SD rats (n = 44) were experimentally infected with 1 × 109 colony forming unit of B. abortus biotype 1 through the intraperitoneal route. Serial serum samples were collected from the rat at 0, 3, 7, 14, 21, 28, 35, 42, 60, 90, and 120 days after inoculation. The sera were tested by enzyme linked immunosorbent assay. We have noticed a very low level and short persistence of IgA antibody in our experiment. The low level and short persistence of IgA antibody suggest that this antibody isotype might not be protective against brucellosis in rats. Both Th1 and Th2 specific immune responses were recorded in our study with the production of IgG1 and IgG2a antibody isotopes, respectively. We noticed significant dominant IgG2a antibody responses over IgG1 responses throughout the experiment (p < 0.001) against WCA and OMP. The mixed Th1 and Th2 dominant immune responses mediated by IgG2a and IgG1 antibody isotypes were observed against CP, PP, and CBP. Data of our study suggest that IgG2a dominant responses in the early stages of disease play the main role in conferring protection against brucellosis and with the progress of disease IgG1 dominant responses were elicited.

First isolation, identification and genetic characterization of Brucella abortus biovar 3 from dairy cattle in Bangladesh.

BACKGROUND: Brucellosis is a zoonotic disease caused by bacteria Brucella spp. belonging to the genus Brucella. It is endemic in domesticated animals in Bangladesh. Isolation, identification and genetic characterization of Brucella spp. in dairy cattle are essential to undertake appropriate control and preventive measures. The study was conducted to isolate and characterize the Brucella spp. circulating in dairy cattle. METHODS: Uterine discharge (n = 45), milk (n = 115), vaginal swab (n = 71), placenta (n = 7) and aborted fetus (n = 2) were collected. Brucella selective agar plates were inoculated with samples and incubated at 37 ◦ C for 14 days under 5% CO2 for isolation of Brucella spp. Brucella suspected colonies were recovered from samples were confirmed by genus and species specific PCR assays. Genetic characterization was performed by Multi Locus Variable number tandem-repeat Analysis-16 (MLVA-16). RESULTS: The isolates of Brucella recovered from samples were confirmed as B. abortus by AMOS-ERY PCR assay. The classical biotyping method confirmed all 10 B. abortus isolates belonged to the biovar 3. The MLVA-16 assay indicated all B. abortus isolates identical and the same genotype 40, based on panel 1 MLVA-8. CONCLUSION: Dendrogram analysis revealed all B. abortus isolates of the study were identical to three isolates from Brazil, one isolate of France and closely related to Chinese isolates. This is the first report of isolation and genetic characterization of B. abortus from the dairy cattle in Bangladesh.

Isolation and identification of bacteria from fresh guava (Psidium guajava) sold at local markets in Mymensingh and their antibiogram profile.

AIM: The study was conducted for the isolation, identification, and antibiogram of bacteria obtained from fresh guava (Psidium guajava). MATERIALS AND METHODS: A total of 25 fresh guavas were collected from five markets located in Mymensingh city. Guava samples were cultured onto various selective media such as eosin methylene blue, xylose lysine deoxycholate, thiosulfate-citrate-bile salts-sucrose, blood agar, and mannitol salt agar for the isolation of bacteria. Biochemical tests (dextrose, maltose, lactose, sucrose, mannitol, methyl red, Voges-Proskauer, and indole) were performed to identify the bacteria. RESULTS: Total viable counts of guava were ranged between log 6.56 colony-forming unit (cfu)/ml and 6.62 cfu/ml. A total of 106 bacterial isolates belonged to five genera (Escherichia coli, Salmonella spp., Vibrio spp., Bacillus spp., and Staphylococcus spp.) were identified. Salmonella spp. (23.6%) was the most prevalent, followed by E. coli (22.64%), Bacillus spp. (19.81%), Staphylococcus spp. (17.92%), and Vibrio spp. (16.03%). The results of antibiotic sensitivity test showed that Salmonella spp., Bacillus spp., and E. coli were sensitive to chloramphenicol, ciprofloxacin, and gentamicin and resistant to ampicillin and cephalexin. Vibrio spp. was sensitive to chloramphenicol and gentamicin, intermediately sensitive to ciprofloxacin and ampicillin and resistant to cephalexin. CONCLUSION: The results of this study indicate that fresh guava contains multidrug-resistant bacteria which might pose a public health risk.

Molecular Detection of Brucella spp. from Milk of Seronegative Cows from Some Selected Area in Bangladesh.

Brucellosis is endemic in Bangladesh both in humans and in animals. A number of reasons complicate the diagnosis, as bovine brucellosis can be diagnosed by various serological tests. But the tests have a limitation; when the organism remains intracellular, the disease goes into chronic stage and the antibody titres may decline. The present study was conducted for isolation and detection of Brucella spp. by polymerase chain reaction (PCR) from seronegative cows. A total of 360 dairy cows from three geographical regions were screened serologically by Rose Bengal Plate Test (RBPT) where 24 samples were serologically positive and the rest of the samples were serologically negative. Among the 24 seropositive individuals, 11 were culture positive and 6 were culture positive from serologically negative dairy cows. The overall seroprevalence of brucellosis in cattle was 6.6% and in disease condition a higher prevalence was recorded in abortion (28.07%) followed by infertility (13.33%). To confirm the Brucella spp. in seronegative dairy cattle, the isolates were extracted and PCR was conducted, which produced 905 bp amplicon size of 6 Brucella spp. from milk sample. So, for the detection or eradication of brucellosis, a bacteriological test and a PCR technique should be performed with the serological test of milk.

Detection of food-borne bacteria in ready to eat betel leaf sold at local markets in Mymensingh.

AIM: The present study was undertaken to determine bacterial load as well as characterize bacterial flora of ready to eat (RTE) betel leaf sold at local markets in Mymensingh city. MATERIALS AND METHODS: A total of 25 RTE betel leaf samples were collected from five local markets such as Kamal-Ranjit (KR) market, Shesh more, Kewatkhali, Jobber more, and Ganginar par. RESULTS: Total viable count of bacteria in betel leaf (log10 mean colony forming unit±standard deviation/ml) was 7.58±0.04 for KR market, 7.72±0.06 for Shesh more, 7.62±0.04 for Kewatkhali, 7.40±0.03 for Jobber more, and 7.60±0.06 for Ganginar par. A total of 98 bacterial isolates belong to five genera (Escherichia coli, Salmonella spp., Vibrio spp., Bacillus spp., and Staphylococcus spp.) were identified. The prevalence of E. coli was 17.34%, Salmonella spp. was 25.51%, Vibrio spp. was 19.39%, Bacillus spp. was 18.37%, and Staphylococcus spp. was 19.39%. Antibiotic sensitivity test showed that all isolates were sensitive to two antibiotics such as ciprofloxacin and gentamicin. Four isolates (E. coli, Salmonella spp., Vibrio spp., and Staphylococcus spp.) were resistant to two antibiotics (ampicillin and cephalexin). Antibiogram profile of bacterial isolates of betel leaf suggests that they were multidrug resistance. CONCLUSION: Data of this study indicate that betel leaf sold at local market harbors multidrug resistance food-borne bacteria which might cause public health hazards if these antibiotic resistant transfer to human through food chain.

Prevalence of colibacillosis in chickens in greater Mymensingh district of Bangladesh.

AIM: This study was conducted for determination of the prevalence of colibacillosis in chicken in poultry farms in Mymensingh and Tangail districts. Isolation, identification, and antibiogram profile of Escherichia coli were also performed. MATERIALS AND METHODS: A total of 25 chickens manifested clinical signs of colibacillosis were collected from five different poultry farms during natural outbreaks. RESULTS: In broiler, the prevalence of colibacillosis was 0.84%, and in layer, prevalence was 0.80%. The prevalence of colibacillosis was 1.0% and 0.5% in 25-30 days old and 31-35 days old broiler, respectively. In case of layer birds, the prevalence was 0.6% in 40-45 days old bird and 1% in 46-50 days old bird. Identity of the E. coli isolate of chicken was confirmed by sugar fermentation, biochemical tests, and polymerase chain reaction assay. Antibiogram profile of E. coli isolate of chicken revealed that it was multidrug resistant (resistant against two antibiotics, such as ampicillin and cefalexin). CONCLUSION: Data of this study suggest that colibacillosis is prevalent in the study areas which underscore the need of implementation of prevention and control measure against this disease.

A review of Brucella seroprevalence among humans and animals in Bangladesh with special emphasis on epidemiology, risk factors and control opportunities.

Brucellosis is a neglected bacterial zoonotic disease in many countries affecting both humans and animals. The aim of this paper is to review published reports of the seroprevalence of brucellosis in humans and animals (cattle, buffalo, sheep, goats and dogs) in Bangladesh. The prevalence studies are based primarily on the following serological tests: rose bengal plate agglutination test (RBT), plate agglutination test (PAT), tube agglutination test (TAT), mercaptoethanol agglutination test (MET), standard tube agglutination test (STAT), slow agglutination test (SAT), milk ring test (MRT), indirect enzyme-linked immunosorbant assay (I-ELISA), competitive ELISA (C-ELISA) and fluorescent polarization assay (FPA). Seroprevalences of brucellosis were found to be affected by the sensitivity and specificity of serological tests employed. Brucellosis prevalence varied based on occupations of people (2.5-18.6%) and species of animals (3.7% in cattle, 4.0% in buffalo, 3.6% in goats and 7.3% in sheep). The prevalence of brucellosis in humans was reported in livestock farmers (2.6-21.6%), milkers (18.6%), butchers (2.5%) and veterinarians (5.3-11.1%) who have direct contact with animal and its products or who consume raw milk. According to published reports brucellosis does affect people and livestock of Bangladesh. There is an immediate need for a concerted effort to control and eradicate brucellosis from domesticated animals in Bangladesh.

Male rats transmit Brucella abortus biotype 1 through sexual intercourse.

The aim of this study was to evaluate transmission of Brucella abortus biotype 1 via sexual intercourse in rats. Male and female virgin Sprague-Dawley (SD) rats were experimentally infected intraperitoneally with 1×10(9)colony forming units (CFU) of B. abortus biotype 1, a Korean bovine isolate. At 14 days after infection, infected male rats (n=10) were housed with uninfected female rats (n=10) and infected female rats (n=10) were housed with uninfected male rats (n=10) for a period of one month. During this period all uninfected female rats became pregnant and 6 of 10 infected female rats became pregnant. Serum from two out of 10 female uninfected rats had positive reactions in the Rose Bengal Plate Agglutination Test (RBPAT), Tube Agglutination Test (TAT) or the Enzyme-Linked Immunosorbent Assay (ELISA); whereas none of the uninfected male rat had positive reactions in these tests. Using bacteriological culture and AMOS-PCR assay, B. abortus biotype 1 was isolated and identified from two uninfected female rats and all of the uninfected male rats were found negative for B. abortus biotype 1. It was concluded that transmission of B. abortus biotype 1 from infected male to uninfected female rats resulted from sexual intercourse.

Rats born to Brucella abortus infected mothers become latent carriers of Brucella.

INTRODUCTION: Rats are known to be infected with Brucella. Vertical transmission of brucellosis was recorded in rats. The study was performed to judge whether rats born from Brucella abortus infected mothers can act as latent carriers of Brucella infection. METHODOLOGY: Female Sprague Dawley (SD) rats were experimentally infected with B. abortus biotype 1 and subsequently bred 10 days post infection (PI). Serum samples of rats (n = 48) born from infected dams were tested using the Rose Bengal plate test (RBPT), tube agglutination test (TAT), and enzyme-linked immunosorbent assay (ELISA) at one, two and three months of age. Tissue samples were plated onto Brucella agar and blood agar media and incubated at 37 °C with 5% CO2 for five to seven days for isolation of bacteria. RESULTS: B. abortus was isolated from 18 out of 48 rats born to infected dams, and the isolates were confirmed as B. abortus by AMOS (B. abortus, melitensis, ovis and suis) PCR assay with the production of a 498 bp PCR amplicon. Serum samples of rats (n = 48) born from infected dams were tested negative using the RBPT, TAT and ELISA at all time points. CONCLUSION: We conclude from the study that rats born to infected dams may become latent carriers of Brucella infection potentially providing a reservoir for future transmission.

Immunoglobulin profiles in acute Brucellosis experimentally induced by Brucella canis in BALB/c mice.

This study evaluated profiles of immunoglobulin (Ig; IgA, IgG, IgG1, and IgG2a) response in experimental brucellosis induced with Brucella canis in BALB/c mice during an 8-week infection period. Six- to 8-week-old BALB/c mice (n = 36) were experimentally infected with 1 × 10(9) CFU of B. canis via the intraperitoneal route. Serial serum samples were collected from the mice at 0, 3, 7, 14, 21, 28, 35, 42, 49, and 56 days after inoculation. The sera were tested by the rapid slide agglutination test (RSAT) and 2-mercaptoethanol-RSAT and indirect enzyme-linked immunosorbent assay. Sera tested positive for B. canis by the RSAT and 2-mercaptoethanol-RSAT beginning from 7 days after inoculation until the end of the experiment. The IgA response was detected at 14 days after infection and reached peak levels at 21 days after infection. The IgG antibody responses were detected at 7 days after infection and reached the peak value at 35 days after infection. Data of our study demonstrated IgG2a-dominant responses over IgG1 during the course of infection (p > 0.05).

Characteristics of the immune response during acute brucellosis in Sprague-Dawley rats.

BACKGROUND: Brucella is a facultative, intracellular pathogen that causes severe disease in animals and humans. Immunity against Brucella involves both humoral and cellular responses. To investigate the characteristics of immune response in acute brucellosis in Sprague-Dawley (SD) rats, IgG and its subclass specific immunoglobulins' (IgG1 and IgG2a) response in sera against B. abortus biotype 1 infection were studied. METHODOLOGY: Thirty-six rats were inoculated intraperitoneally with 0.1 ml apyrogenic saline containing 1x10(10) colony forming unit (CFU) of B. abortus biotype 1 Korean bovine isolate. Four rats were used as uninfected controls. The sera were collected from infected rats at 3, 7, 14, 21, 28, 35, 42, 49, and 56 days post infection (DPI) and screened for Brucella specific antibody response by the rose bengal plate test (RBPT). IgG and its subclass specific immunoglobulins' (IgG1 and IgG2a) response in the sera were measured by a lipopolysaccharide (LPS) based indirect enzyme-linked immunosorbent assay (IELISA). RESULTS: Brucella specific IgG, IgG1 and IgG2a responses in the sera of infected rats were detected from 3 DPI by IELISA. IgG and IgG1 concentrations in sera reached the peak level at 35 DPI, and then the concentrations gradually declined to the end of the experiment. IgG2a concentrations in the sera remained almost constant from 7 DPI until the end of this study. CONCLUSION: In acute brucellosis, IgG2a response (indicative of a Th1 response) was found to be significantly dominant over IgG1 response (indicative of Th2 response) (P < 0.001).