Mycoplasma bovis mastitis in dairy cattle.

Mycoplasma bovis has recently been identified increasingly in dairy cows causing huge economic losses to the dairy industry. M. bovis is a causative agent for mastitis, pneumonia, endometritis, endocarditis, arthritis, otitis media, and many other clinical symptoms in cattle. However, some infected cows are asymptomatic or may not shed the pathogen for weeks to years. This characteristic of M. bovis, along with the lack of adequate testing and identification methods in many parts of the world until recently, has allowed the M. bovis to be largely undetected despite its increased prevalence in dairy farms. Due to growing levels of antimicrobial resistance among wild-type M. bovis isolates and lack of cell walls in mycoplasmas that enable them to be intrinsically resistant to beta-lactam antibiotics that are widely used in dairy farms, there is no effective treatment for M. bovis mastitis. Similarly, there is no commercially available effective vaccine for M. bovis mastitis. The major constraint to developing effective intervention tools is limited knowledge of the virulence factors and mechanisms of the pathogenesis of M. bovis mastitis. There is lack of quick and reliable diagnostic methods with high specificity and sensitivity for M. bovis. This review is a summary of the current state of knowledge of the virulence factors, pathogenesis, clinical manifestations, diagnosis, and control of M. bovis mastitis in dairy cows.

Efficacy of novel staphylococcal surface associated protein vaccines against Staphylococcus aureus and non-aureus staphylococcal mastitis in dairy cows.

Mastitis is an inflammation of the mammary gland commonly caused by bacteria or fungi. Staphylococcus aureus is a major bacterium that causes mastitis in dairy cows. Non-aureus staphylococci are also increasingly reported, with Staphylococcus chromogenes being the most common species. Current staphylococcal mastitis control programs are not fully effective, and treatment with antibiotics is not sustainable. Non-antibiotic sustainable control tools, such as effective vaccines, are critically needed. We previously developed S. aureus surface-associated proteins (SASP) and S. chromogenes surface-associated proteins (SCSP) vaccines that conferred partial protective effects. We hypothesized that vaccination with SASP or SCSP would reduce the incidence of S. aureus mastitis throughout the lactation period. The objective of this study was to evaluate the efficacy of SASP and SCSP vaccines against S. aureus and non-aureus staphylococcal mastitis under natural exposure over 300 days of lactation. Pregnant Holstein dairy cows (n = 45) were enrolled and assigned to receive SASP (n = 15) or SCSP (n = 16) vaccines or unvaccinated control (n = 14). Cows were vaccinated with 1.2 mg of SASP or SCSP with Emulsigen-D adjuvant. Control cows were injected with phosphate-buffered saline with Emulsigen-D adjuvant. Three vaccine injections were given subcutaneously at 60, 40, and 20 days before the expected calving. Booster vaccinations were given at 120 and 240 days in milk. Cows were monitored for mastitis at quarter and cow levels, staphylococcal mastitis incidence, changes in serum and milk anti-SASP and anti-SCSP antibody titers, bacterial counts in milk, adverse reactions, milk yield and milk somatic cells count over 300 days of lactation. The SCSP vaccine conferred a significant reduction in the incidence of staphylococcal mastitis. Milk and serum anti-SASP and anti-SCSP antibody titers were increased in the vaccinated cows compared to unvaccinated control cows. Anti-SASP and anti-SCSP antibody titers decreased at about 120 days in milk, indicating the duration of immunity of about four months. In conclusion, the SASP and SCSP vaccines conferred partial protection from natural infection.

Molecular epidemiology and pathogenomics of extended-spectrum beta-lactamase producing- Escherichia coli and - Klebsiella pneumoniae isolates from bulk tank milk in Tennessee, USA.

Introduction: The rise in extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae in dairy cattle farms poses a risk to human health as they can spread to humans through the food chain, including raw milk. This study was designed to determine the status, antimicrobial resistance, and pathogenic potential of ESBL-producing -E. coli and -Klebsiella spp. isolates from bulk tank milk (BTM). Methods: Thirty-three BTM samples were collected from 17 dairy farms and screened for ESBL-E. coli and -Klebsiella spp. on CHROMagar ESBL plates. All isolates were confirmed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) and subjected to antimicrobial susceptibility testing and whole genome sequencing (WGS). Results: Ten presumptive ESBL-producing bacteria, eight E. coli, and two K. pneumoniae were isolated. The prevalence of ESBL-E. coli and -K. pneumoniae in BTM was 21.2% and 6.1%, respectively. ESBL-E. coli were detected in 41.2% of the study farms. Seven of the ESBL-E. coli isolates were multidrug resistant (MDR). The two ESBL-producing K. pneumoniae isolates were resistant to ceftriaxone. Seven ESBL-E. coli strains carry the blaCTX-M gene, and five of them co-harbored blaTEM-1. ESBL-E. coli co-harbored blaCTX-M with other resistance genes, including qnrB19, tet(A), aadA1, aph(3'')-Ib, aph(6)-Id), floR, sul2, and chromosomal mutations (gyrA, gyrB, parC, parE, and pmrB). Most E. coli resistance genes were associated with mobile genetic elements, mainly plasmids. Six sequence types (STs) of E. coli were detected. All ESBL-E. coli were predicted to be pathogenic to humans. Four STs (three ST10 and ST69) were high-risk clones of E. coli. Up to 40 virulence markers were detected in all E. coli isolates. One of the K. pneumoniae was ST867; the other was novel strain. K. pneumoniae isolates carried three types of beta-lactamase genes (blaCTX-M, blaTEM-1 and blaSHV). The novel K. pneumoniae ST also carried a novel IncFII(K) plasmid ST. Conclusion: Detection of high-risk clones of MDR ESBL-E. coli and ESBL-K. pneumoniae in BTM indicates that raw milk could be a reservoir of potentially zoonotic ESBL-E. coli and -K. pneumoniae.

Prevalence and antimicrobial resistance profiles of extended-spectrum beta-lactamase-producing Escherichia coli in East Tennessee dairy farms.

Introduction: The extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae, such as Escherichia coli, are emerging as a serious threat to global health due to their rapid spread and their multidrug-resistant (MDR) phenotypes. However, limited information is available regarding the prevalence and antimicrobial resistance (AMR) profile of ESBL-E. coli in the United States dairy farms. This study aimed to determine the prevalence and AMR pattern of ESBL-E. coli in East Tennessee dairy cattle farms. Methods: Rectal fecal samples from dairy cattle (n = 508) and manure (n = 30), water (n = 19), and feed samples (n = 15) were collected from 14 farms. The presumptive E. coli was isolated on CHROMagar™ ESBL and confirmed by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). Antimicrobial susceptibility testing was performed on the ESBL-E. coli isolates. Results and discussion: From 572 fecal and farm environmental samples, a total of 233 (41%, n = 572) ESBL-E. coli were identified. The prevalence of fecal ESBL-E. coli was 47.5% (95% CI: 46.2-49.2). The within-farm prevalence of ESBL-E. coli ranged from 8 to 100%. Recent treatment history with third-generation cephalosporins (3GC), cow parity ≥3, and calves were the independent risk factors associated (P < 0.05) with fecal carriage of ESBL-E. coli. Overall, 99.6% (n = 231) ESBL-E. coli tested were phenotypically resistant to at least one of the 14 antimicrobial agents tested. The most common AMR phenotypes were against beta-lactam antibiotics, ampicillin (99.1%; n = 231 isolates), and ceftriaxone (98.7%, n = 231). Most ESBL-E. coli isolates (94.4%) were MDR (resistance to ≥3 antimicrobial classes), of which 42.6% showed co-resistance to at least six classes of antimicrobials. ESBL-E. coli isolates with concurrent resistance to ceftriaxone, ampicillin, streptomycin, tetracycline, sulfisoxazole, and chloramphenicol are widespread and detected in all the farms. The detection of MDR ESBL-E. coli suggests that dairy cattle can be a reservoir for these bacteria, highlighting the associated public health risk.

Regulation Mechanisms of Virulence Genes in Enterohemorrhagic Escherichia coli.

Enterohemorrhagic Escherichia coli (EHEC) is one of the most common E. coli pathotypes reported to cause several outbreaks of foodborne illnesses. EHEC is a zoonotic pathogen, and ruminants, especially cattle, are considered important reservoirs for the most common EHEC serotype, E. coli O157:H7. Humans are infected indirectly through the consumption of food (milk, meat, leafy vegetables, and fruits) and water contaminated by animal feces or direct contact with carrier animals or humans. E. coli O157:H7 is one of the most frequently reported causes of foodborne illnesses in developed countries. It employs two essential virulence mechanisms to trigger damage to the host. These are the development of attaching and effacing (AE) phenotypes on the intestinal mucosa of the host and the production of Shiga toxin (Stx) that causes hemorrhagic colitis and hemolytic uremic syndrome. The AE phenotype is controlled by the pathogenicity island, the locus of enterocyte effacement (LEE). The induction of both AE and Stx is under strict and highly complex regulatory mechanisms. Thus, a good understanding of these mechanisms, major proteins expressed, and environmental cues involved in the regulation of the expression of the virulence genes is vital to finding a method to control the colonization of reservoir hosts, especially cattle, and disease development in humans. This review is a concise account of the current state of knowledge of virulence gene regulation in the LEE-positive EHEC.

Prevalence of Antimicrobial Resistant and Extended-Spectrum Beta-Lactamase-producing Escherichia coli in Dairy Cattle Farms in East Tennessee.

Antimicrobials have been widely used in dairy farms to prevent and control dairy cattle diseases since 1960s. This led to the emergence of antimicrobial resistant bacteria (ARB) that, along with their antimicrobial resistance genes (ARGs), can spread from dairy farms to humans. Therefore, regular antimicrobial resistance (AMR) monitoring is important to implement proper mitigation measures. The objective of this study was to determine the prevalence of AMR and extended-spectrum beta-lactamases (ESBLs)-producing Escherichia coli in dairy cattle. A cross-sectional study was conducted in four dairy cattle farms (A-D) in East Tennessee. A total of 80 samples consisting of 20 samples each of bulk tank milk, feces, dairy cattle manure-amended soil, and prairie soil adjacent to the farms were collected and cultured for the isolation of E. coli. Tetracycline (TETr)-, third-generation cephalosporin (TGCr)- and nalidixic acid (NALr)-resistant E. coli (n = 88) were isolated and identified on agar media supplemented with TET, cefotaxime, and NAL, respectively. TGCr E. coli were tested for ESBLs and other coselected ARGs. TETr (74%, n = 88) was the most common, followed by TGCr (20%) and NALr (8%). Farms had significant (p < 0.001) differences: the highest prevalence of TGCr (55%) and TETr (100%) were observed in farm D, while all NALr isolates were from farm C. Over 83% of TGCr isolates (n = 18) harbored ESBL gene blaCTX-M. Majority (78%) of the E. coli isolates were multidrug-resistant (MDR), being positive for beta-lactams (blaCTX-M), TETs tet(A), tet(B), tet(M)), sulfonamides (sul2), aminoglycosides (strA), and phenicols (floR). This study indicated the widespread occurrence of MDR ESBLs-E. coli in dairy cattle farms. AMR surveillance of more dairy farms and identification of farm-level risk factors are important to mitigate the occurrence and spread of ARB of significant public health importance, such as ESBLs-E. coli.

Polio outbreak response in Ethiopia.

BACKGROUND: Ethiopia had been polio-free for almost four years until December 2004. However, between December 2004 and February 2006, 24 children were paralysed as a result of infection with wild poliovirus imported from the neighbouring country of Sudan. In response, the country has attempted to document the impact of various response measures on the containment of wild poliovirus transmission. OBJECTIVES: This study aims at systematic and epidemiological assessment of the extent of the outbreak, its determinants, and the lessons learned as well as the implications for future control strategies to interrupt wild poliovirus transmission. DESIGN: A cross-sectional study design with qualitative and quantitative data collection approaches was used to conduct the epidemiologic assessment. SUBJECTS: All confirmed wild poliovirus cases, and reported acute flaccid paralysis cases in close proximity to the confirmed polio cases were the study subjects. Child caretakers and health service providers were interviewed as part of the investigation. RESULTS: Between December 2004 and February 2006, eight children from Tigray Regional State, nine children from Amhara Regional State and seven children from Oromia Regional State were paralysed as a result of infection with wild poliovirus type 1. Genetic sequencing demonstrated two separate importations to Ethiopia. Risk factors that may have facilitated spread of the outbreak within the country included gaps in vaccination coverage and interruption of the cold chain system, gaps in acute flaccid paralysis surveillance performance, high population mobility, poor environmental sanitation, crowded living conditions and unsafe drinking water. In response to the outbreak, Ethiopia conducted detailed outbreak investigations within two days of confirmation of the index cases. Large-scale, house-to-house vaccination campaigns were also implemented. As a result, the three regions interrupted the wild poliovirus transmission within the regions within one year of confirmation of the index case. CONCLUSION: Outbreak response activities were successful in interrupting the imported wild poliovirus transmission in Tigray, Amhara and Oromia Regional States of Ethiopia within a one-year period of time. In Ethiopia, programme strategies should be intensified to contain further spread and prevent future importation of wild poliovirus. Large-scale immunisation campaigns should reach every child, including those isolated by geography, poverty and security.

National EPI coverage survey report in Ethiopia, 2006

Background: Routine EPI reports have shown an upward trend in immunization coverage in recent years in Ethiopia; however; regional disparities exist. Objective: To determine regional coverage of child and TT immunization and assess reasons for not utilizing immunization services. Methods: The revised 2005 WHO-EPI regional coverage cluster survey method was used to determine the sample size for the study. Regional immunization status of 12-23 months of children and mothers with 0-11 months of infants forchild immunization and TT immunization respectively were taken as the unit of analysis. A sample of 6;903 children between 12-23 months and 6;952 mothers with infants between 0-11 months from 468 clusters in 11 regions of the country were surveyed in June 2006. Results: The weighted national immunization coverage assessed by card plus history for children aged 12-23 months vaccinated before the age of one year was BCG 83.4; DPT1 84.3; DPT3 66.0; measles 54.3; and fully immunized children 49.9. The weighted national TT2+ coverage and rate of Protection at Birth (PAB) assessed by card plus history was 75.6and 63.0respectively. Conclusion: The survey showed a 10 percentage point of increment in DPT3 coverage compared to 2001 survey coverage. However; progress was not uniform in all regions of the country. Despite the improve-ment in the access to immunization in the country; DPT3 coverage was less than 30and dropout rate remained very high in three emerging regions. Effective behavioral change communication (BCC) strategies need to be designed and implemented to tackle high dropout rate in the program. Besides; health workers training program on interpersonal communication and Reaching Every District (RED) approach should be fully implemented to increase and sustain high level of immunization coverage in Ethiopia

Effect of Zinc Supplementation in Treatment of Acute Diarrhoea among 2-59 Months Children Treated in Black Lion Hospital; Addis Ababa; Ethiopia

Background: Diarrhoeal disease is one of the major causes of morbidity and mortality in under five children.Worldwide; there are about 1.3 million under five children deaths attributable to diarrhea. Health status in Ethiopia is one of the lowest in the world with estimated health service coverage of 60; and diarrhoeal disease remains one of the major causes of under five morbidity and mortality. Treatment with ORS does not affect the duration and severity of diarrhoea; hence acceptance of ORS is low and diarrhoea still remains the major cause of child morbidity and mortality. Diarrhoea is a commonly associated problem in children with Zinc deficiency and also leads to excess zinc losses. Objective: To assess variations in the usage of antimicrobial and/or antidiarreals in children with acute watery diarrhoea randomized to receive zinc supplementation as compared to those who do not receive it; and assess the adherence to zinc supplementation given with ORS in the management of an episode of acute watery diarrhoea. Methodology: This is part of a multicentre; multi-disciplinary; randomized and open effectiveness trial conducted in out-patient settings in Addis Ababa; Black Lion Hospital at the Department of Paediatrics. The sample size has been calculated for a two-tailed alpha of 0.05 and power of 0.2. Children aged 2-59 months and who presented with acute watery diarrhoea for less than 7 days were recruited. Results: There were 188 children randomized to the Zinc plus ORS arm and 226 children to the ORS arm. There were 193 (46.6) females and 221 (53.4) males. Fifty two percent of the cases were between 2-11 months of age and decreasing trend of proportion of older children was observed in the study population (P=0.0001). Zinc adherence rate was 95. Seventy three (39.3) patients from Zinc + ORS group and 71 (32.3) patients from ORS group took ORS when they came for the first follow up visit (P-value=0.115). From the total study subjects 16.1took antibiotic or antidiarhael tablets before randomization which was significantly higher than the second follow up visit observation with only 1.7(P=0.0001). Only 3 (1.7) patients from Zinc arm and 4 (1.8) patients from ORS arms took antibiotic/anti diarrhoeal on the second follow up visits. Conclusion: Proper counselling of care takers significantly reduces unnecessary use of antibiotic/anti diarrhoea drugs in the treatment of childhood diarrhoea. Zinc supplementation in the treatment of childhood diarrhoea is well tolerated by patients and there is good compliance of care takers. However; we could not observe any significant difference in antibiotic/antidiarheal drug use between ORS and ORS plus Zinc groups