Quantitative Bacteriological Culture Research Articles

A análise dos sedimentos urinários corado e não-corado de cães está de acordo com a cultura microbiológica?

ABSTRACT: Diagnosis of bacteriuria in veterinary medicine is commonly based on unstained urinary sediment evaluation. Nonetheless, amorphous particles can be confused with bacteria. This study aims to investigate whether the stained sediment increases the sensitivity and specificity of bacteriuria detection. One hundred urine samples were collected, with 60 obtained through voided specimens and 40 through catheterization, from dogs of various breeds, genders, and ages. Additionally, a 1 ml aliquot from each sample was subjected to quantitative bacteriological culture, serving as the gold standard test for comparison with the sediment analysis. Comparing to the bacteriology culture, the stained sediment of urine collected by catheterization exhibited a relative sensitivity of 60% and specificity of 70%, while to voided specimens showed a sensitivity of 93.3% and specificity of 57.8%. Unstained sediment presented a sensitivity of 100% and specificity of 10% to urine collected by catheterization, and 93.3% and 4.4% to voided samples, respectively. Both stained and unstained methods demonstrated negative predictive values > 60%, but the positive predictive value of unstained sediment ranged to 24.6% (voided samples) to 27% (catheterization) indicating a lower probability of true positives. Both techniques showed a low correlation coefficient (kappa) indicating that they cannot replace the gold standard method for confirming bacteriuria. However, Gram staining of urinary sediment improved the differentiation between amorphous substances and bacteriuria in canine urine samples, suggesting its potential applicability in laboratory routines.

Dynamics of Macrophages and Polymorphonuclear Leukocytes Milk-Secreted by Buffaloes with Udders Characterized by Different Clinical Status.

The study evaluated the dynamics of macrophages and polymorphonuclear leukocytes milk-secreted by Mediterranean Buffaloes (MBs). Sixty quarter-milk-samples were collected and divided into three groups (n = 20 units each one): clinical mastitis (CM), subclinical mastitis (SCM), and intramammary infection (IMI). The control group consisted of an additional 20 healthy quarters. Their health status was assessed by clinical examination, quantitative somatic cell count (QSCC) and bacteriological milk culture. Finally, a differential somatic cell count (DSCC) was performed on all the milk samples. The mean percentage of macrophages, both in CM- and SCM-quarters, showed a significant difference as compared with the healthy-ones. Significant differences were also detected comparing the mean percentages of polymorphonuclear leukocytes between CM- and healthy-quarters, SCM and healthy, IMI and healthy. The QSCC revealed a weak-significant-negative-correlation with the quantitation of macrophages (r = −0.388), and a moderate-significant-positive-correlation with the polymorphonuclear leukocytes (r = 0.477). Macrophages and polymorphonuclear leukocytes showed a weak-significant-negative-correlation between them (r = −0.247). The interpretation of macrophages and polymorphonuclear leukocytes dynamics in milk provided beneficial information regarding the clinical status of the quarters enrolled. Future studies exploring the potential use of DSCC to improve udder health represent an interesting perspective in these ruminants.

In-treatment monitoring and use of a novel topical therapy shorten the duration to eliminate Taylorella asinigenitalis in donkey stallions

Postarrival quarantine testing of a consignment of imported miniature donkeys (Equus asinus) with a duplex Taylorella equigenitalis/asinigenitalis real-time quantitative PCR (qPCR) assay and bacteriological culture identified T asinigenitalis in one...

Short communication: Comparing real-time PCR and bacteriological cultures for Streptococcus agalactiae and Staphylococcus aureus in bulk-tank milk samples

For more than 30 yr, a control plan for Streptococcus agalactiae and Staphylococcus aureus has been carried out in more than 1,500 dairy herds of the province of Brescia (northern Italy). From 2010 to 2011, the apparent prevalence of Strep. agalactiae has been relatively stable around 10%, but the apparent prevalence of Staph. aureus has been greater than 40% with an increasing trend. The aim of this paper was to estimate and compare the diagnostic accuracy of 3 assays for the detection of Strep. agalactiae and Staph. aureus in bulk-tank milk samples (BTMS) in field conditions. The assays were a qualitative and a quantitative bacteriological culture (BC) for each pathogen and a homemade multiplex real-time PCR (rt-PCR). Because a gold standard was not available, the sensitivities (Se) and specificities (Sp) were evaluated using a Bayesian latent class approach. In 2012 we collected one BTMS from 165 dairy herds that were found positive for Strep. agalactiae in the previous 2-yr campaigns of eradication plan. In most cases, BTMS collected in these herds were positive for Staph. aureus as well, confirming the wide spread of this pathogen. At the same time we also collected composite milk samples from all the 8,624 lactating cows to evaluate the within-herd prevalence of Strep. agalactiae. Streptococcus agalactiae samples were cultured using a selective medium Tallium Kristalviolette Tossin, whereas for Staph. aureus, we used Baird Parker modified medium with added Rabbit Plasma Fibrinogen ISO-Formulation. In parallel, BTMS were tested using the rt-PCR. Regarding Strep. agalactiae, the posterior median of Se and Sp of the 2 BC was similar [qualitative BC: Se=98%, posterior credible interval (95%PCI): 94–100%, and Sp=99%, 95%PCI: 96–100%; quantitative BC: Se=99%, 95%PCI: 96–100%, and Sp=99%, 95%PCI: 95–100%] and higher than those of the rt-PCR (at 40 cycle threshold, Se=92%, 95%PCI: 85–97%; Sp=94%, 95%PCI: 88–98%). Also in case of Staph. aureus, the posterior medians of BC were generally higher than those of rt-PCR. In fact, although the Se of BC was slightly lower (rt-PCR at 40 cycle threshold, median Se=99%, 95%PCI: 97–100%, and qualitative BC, median Se=94%, 95%PCI: 87–99%), the Sp was much higher (rt-PCR at 40 cycle threshold, median Sp=67%, 95%PCI: 38–97%; qualitative BC, median Sp=95%; 95%PCI: 76–100%). Our study confirms that BC and rt-PCR are reliable diagnostic tools to detect Strep. agalactiae and Staph. aureus, and rt-PCR results should be confirmed by BC carried out on BTMS and possibly on composite milk samples.

Prevalence of bacteriuria in dogs without clinical signs of urinary tract infection presenting for elective surgical procedures

To determine the frequency of bacteriuria in dogs presenting for elective surgery, to compare the frequency of bacteriuria in dogs presenting for orthopaedic (non-neurological) procedures to that of dogs presenting for soft tissue procedures and to measure the agreement of microscopic visualisation of bacteria in urine sediment with the occurrence of bacterial growth on culture. Prospective cohort study of 140 client-owned dogs. Urine was collected via prepubic cystocentesis prior to or immediately after induction of anaesthesia. Urine was submitted for quantitative bacteriological culture and urinalysis. The dogs' age, sex, weight and breed were recorded, as well as the surgical procedure performed. In total, 80 orthopaedic and 60 soft tissue surgical cases were included in the study; 3 dogs (2.1%) returned bacterial growth on culture (positive urine culture) and 19 (13.6%) recorded urine sediment with pyuria and/or bacteriuria on urinalysis (positive urinalysis). All dogs with positive urine culture were female and two of them underwent orthopaedic procedures. Each bitch had growth of Escherichia coli >10(5) CFU/mL. The agreement between positive urinalysis and positive urine culture was poor (κ = 0.15). The prevalence of bacteriuria in dogs without clinical signs of urinary tract infection in this population was low (2.1%). An at-risk population could not be identified because of the small number of positive outcomes. A positive urinalysis showed poor agreement with urine culture results and therefore the decision to treat without performing a urine culture is not advised.

Bench‐top validation testing of selected immunological and molecular Renibacterium salmoninarum diagnostic assays by comparison with quantitative bacteriological culture

No gold standard assay exhibiting error-free classification of results has been identified for detection of Renibacterium salmoninarum, the causative agent of salmonid bacterial kidney disease. Validation of diagnostic assays for R.salmoninarum has been hindered by its unique characteristics and biology, and difficulties in locating suitable populations of reference test animals. Infection status of fish in test populations is often unknown, and it is commonly assumed that the assay yielding the most positive results has the highest diagnostic accuracy, without consideration of misclassification of results. In this research, quantification of R.salmoninarum in samples by bacteriological culture provided a standardized measure of viable bacteria to evaluate analytical performance characteristics (sensitivity, specificity and repeatability) of non-culture assays in three matrices (phosphate-buffered saline, ovarian fluid and kidney tissue). Non-culture assays included polyclonal enzyme-linked immunosorbent assay (ELISA), direct smear fluorescent antibody technique (FAT), membrane-filtration FAT, nested polymerase chain reaction (nested PCR) and three real-time quantitative PCR assays. Injection challenge of specific pathogen-free Chinook salmon, Oncorhynchus tshawytscha (Walbaum), with R.salmoninarum was used to estimate diagnostic sensitivity and specificity. Results did not identify a single assay demonstrating the highest analytical and diagnostic performance characteristics, but revealed strengths and weaknesses of each test.

A comprehensive microbiological evaluation of fifty-four patients undergoing revision surgery due to prosthetic joint loosening

The diagnosis of a chronic prosthetic joint infection (PJI) is challenging, and no consensus exists regarding how best to define the criteria required for microbiological identification. A general view is that culture of periprosthetic biopsies suffers from inadequate sensitivity. Recently, molecular analyses have been employed in some studies but the specificity of molecular analyses has been questioned, mainly due to contamination issues. In a prospective study of 54 patients undergoing revision surgery due to prosthetic joint loosening, we focused on two aspects of microbiological diagnosis of chronic PJI. First, by collecting diagnostic specimens in a highly standardized manner, we aimed at investigating the adequacy of various specimens by performing quantitative bacteriological culture. Second, we designed and performed real-time 16S rRNA gene PCR analysis with particular emphasis on minimizing the risk of false-positive PCR results. The specimens analysed included synovial fluid, periprosthetic biopsies from the joint capsule and the interface membrane, and specimens from the surface of the explanted prosthesis rendered accessible by scraping and sonication. No antibiotics were given prior to specimen collection. Based on five diagnostic criteria recently suggested, we identified 18 PJIs, all of which fulfilled the criterion of ≥2 positive cultures of periprosthetic specimens. The rate of culture-positive biopsies from the interface membrane was higher compared to specimens from the joint capsule and synovial fluid, and the interface membrane contained a higher bacterial load. Interpretational criteria were applied to differentiate a true-positive PCR from potential bacterial DNA contamination derived from the reagents used for DNA extraction and amplification. The strategy to minimize the risk of false-positive PCR results was successful as only two PCR results were false-positive out of 216 negative periprosthetic specimens. Although the PCR assays themselves were very sensitive, three patients with low bacterial numbers in periprosthetic specimens tested negative by real-time PCR. This overall lowered sensitivity is most likely due to the reduced specimen volume used for PCR analysis compared to culture and may also be due to interference from human DNA present in tissue specimens. According to the protocol in the present study, 16S rRNA gene real-time PCR did not identify more cases of septic prosthetic loosening than did culture of adequate periprosthetic biopsies.

Detection of Salmonella Enteritidis in asymptomatic carrier animals: comparison of quantitative real-time PCR and bacteriological culture methods

Quantification of Salmonella in asymptomatic carrier animals can be used to assess microbial risk and monitor the level of contamination in domestic animals used for food production. We examined the sensitivity, specificity and accuracy of real-time qPCR, without pre-enrichment or selective enrichment stages, for the quantification of S. enterica serovar Enteritidis in resistant mice, as a model of asymptomatic carrier animal. The results were compared with those obtained by traditional bacteriological culture methods, the gold standard test. Two hundred and forty-three samples, including spleen, liver, mesenteric lymph nodes, portions of intestine, intestinal content of the ileocecal portion, and feces, were collected from a group of 27 C57BL/6 mice, that had been intragastrically inoculated with high doses of S. enterica serovar Enteritidis. The real-time qPCR assay presented a consistent linearity of the standard curve (r(2) = 0.999), with very low differences between melting temperatures, and low coefficients of variation in intra- (< 1%) and interassay (< 2%) comparisons. The primers were highly specific; there was no amplification with other Salmonella serovars or with DNA from uninfected tissues and feces from mice. The detection limit of the technique was defined as 32 copies of S. enterica serovar Enteritidis. A sensitivity of 90%, a specificity of 77% and an accuracy of 79% were obtained. The higher sensitivity of PCR was reflected in a kappa coefficient of 0.41, showing moderate agreement between tests. We conclude that real-time qPCR is a good alternative for diagnostic scanning in asymptomatic carrier animals, due to its high sensitivity and rapidity.

Analysis of the sporicidal activity of chlorine dioxide disinfectant against Bacillus anthracis (Sterne strain)

Routine surface decontamination is an essential hospital and laboratory procedure, but the list of effective, noncorrosive disinfectants that kill spores is limited. We investigated the sporicidal potential of an aqueous chlorine dioxide solution and encountered some unanticipated problems. Quantitative bacteriological culture methods were used to determine the log(10) reduction of Bacillus anthracis (Sterne strain) spores following 3min exposure to various concentrations of aqueous chlorine dioxide solutions at room temperature in sealed tubes, as well as spraying onto plastic and stainless steel surfaces in a biological safety cabinet. Serial 10-fold dilutions of the treated spores were then plated on 5% sheep blood agar plates, and the survivor colonies were enumerated. Disinfection of spore suspensions with aqueous chlorine dioxide solution in sealed microfuge tubes was highly effective, reducing the viable spore counts by 8log(10) in only 3min. By contrast, the process of spraying or spreading the disinfectant onto surfaces resulted in only a 1log(10) kill because the chlorine dioxide gas was rapidly vaporised from the solutions. Full potency of the sprayed aqueous chlorine dioxide solution was restored by preparing the chlorine dioxide solution in 5% bleach (0.3% sodium hypochlorite). The volatility of chlorine dioxide can cause treatment failures that constitute a serious hazard for unsuspecting users. Supplementation of the chlorine dioxide solution with 5% bleach (0.3% sodium hypochlorite) restored full potency and increased stability for one week.

Association of soil concentrations of Rhodococcus equi and incidence of pneumonia attributable to Rhodococcus equi in foals on farms in central Kentucky

To determine whether soil concentrations of total or virulent Rhodococcus equi differed among breeding farms with and without foals with pneumonia caused by R equi. 37 farms in central Kentucky. Procedures-During January, March, and July 2006, the total concentration of R equi and concentration of virulent R equi were determined by use of quantitative bacteriologic culture and a colony immunoblot technique, respectively, in soil specimens obtained from farms. Differences in concentrations and proportion of virulent isolates within and among time points were compared among farms. Soil concentrations of total or virulent R equi did not vary among farms at any time point. Virulent R equi were identified in soil samples from all farms. Greater density of mares and foals was significantly associated with farms having foals with pneumonia attributable to R equi. Among farms with affected foals, there was a significant association of increased incidence of pneumonia attributable to R equi with an increase in the proportion of virulent bacteria between samples collected in March and July. Results indicated that virulent R equi were commonly recovered from soil of horse breeding farms in central Kentucky, regardless of the status of foals with pneumonia attributable to R equi on each farm. The incidence of foals with pneumonia attributable to R equi can be expected to be higher at farms with a greater density of mares and foals.

Evaluation of fecal samples from mares as a source of Rhodococcus equi for their foals by use of quantitative bacteriologic culture and colony immunoblot analyses

To determine whether mares are a clinically important source of Rhodococcus equi for their foals. 171 mares and 171 foals from a farm in Kentucky (evaluated during 2004 and 2005). At 4 time points (2 before and 2 after parturition), the total concentration of R equi and concentration of virulent R equi were determined in fecal specimens from mares by use of quantitative bacteriologic culture and a colony immunoblot technique, respectively. These concentrations for mares of foals that developed R equi-associated pneumonia and for mares with unaffected foals were compared. Data for each year were analyzed separately. R equi-associated pneumonia developed in 53 of 171 (31%) foals. Fecal shedding of virulent R equi was detected in at least 1 time point for every mare; bacteriologic culture results were positive for 62 of 171 (36%) mares at all time points. However, compared with dams of unaffected foals, fecal concentrations of total or virulent R equi in dams of foals with R equi-associated pneumonia were not significantly different. Results indicate that dams of foals with R equi-associated pneumonia did not shed more R equi in feces than dams of unaffected foals; therefore, R equi infection in foals was not associated with comparatively greater fecal shedding by their dams. However, detection of virulent R equi in the feces of all mares during at least 1 time point suggests that mares can be an important source of R equi for the surrounding environment.

Relationship between airway colonization, inflammation and exacerbation frequency in COPD

To evaluate bacterial colonization and the airway inflammatory response, and its relationship to the frequency of exacerbation in patients with stable chronic obstructive pulmonary disease (COPD). Quantitative bacteriologic cultures, neutrophil elastase, myeloperoxidase (MPO), tumor necrosis factor alpha (TNF-alpha) and interleukin (IL)-8 were measured in bronchoalveoler lavage (BAL) in 39 patients with stable COPD [19 with frequent exacerbation (> or = 3/year), and 20 with infrequent] and in 18 healthy controls (10 smokers and 8 non-smokers). BAL revealed the microorganisms with potential pathogenicity above the established threshold (> or = 10(3)cfu/ml) in 68.4% of patients with frequent exacerbation, 55% of infrequent exacerbation, 40% of smokers and 12.5% of non-smokers controls (P=0.05). BAL MPO, IL-8 and TNF-alpha levels were found to be significantly higher in COPD as compared to controls (P=0.001). However, only IL-8 level was significantly higher in COPD patients with frequent exacerbation as compared to infrequent (P=0.001). Airway bacterial load correlated with levels of airway inflammation markers in COPD (P<0.05). The bacterial load and airway inflammation contributes to each other in stable COPD. However, there is a link only between interleukine (IL)-8 and frequent exacerbations. Clearly, the relationship between bacterial colonization, airway inflammation and frequent exacerbations is of major importance in understanding of the COPD pathogenesis.

Labelling and Content Evaluation of Commercial Veterinary Probiotics

The aim of our study was to evaluate the contents and labelling of five commercial probiotics marketed for veterinary administration. The information on the product was obtained from the inserted leaflet or the data on the package. Quantitative bacteriological culture was performed in all products, and isolates were identified via biochemical characteristics. Comparison of actual contents versus label claims was performed. Four products correctly provided information on expiry dates, species and quantity of bacteria per gram or kilogram of product. In one product, there was no probiotic species mentioned in the Czech text on the package. Culture examinations of all the three products containing Enterococcus faecium resulted in finding the declared quantity of bacteria. They also contained Lactobacillus sp. not mentioned in the leaflet. Culturing the mixture of Bacillus subtilis and Lactobacillus paracasei, we found only Bacillus subtilis in a quantity by one order lower than declared. In an incorrectly labelled product, Lactobacillus sp. was found instead of yeast species. Most commercial veterinary probiotic preparations are not accurately represented by label claims.

Screening urine samples for significant bacteriuria in the clinical microbiology laboratory

Urine specimens for quantitative bacteriologic culture represent one of the most common samples submitted to the clinical microbiology laboratory for testing. Although quantitative urine culture represents the established “gold standard” for the laboratory diagnosis of a urinary tract infection, it represents a labor-intensive, time-consuming, and expensive activity in which over 60% of all samples processed show no evidence of significant bacterial growth. Several semi-automated and automated systems have been developed for the initial screening of urine samples for detecting the presence of significant bacteriuria. The availability of such a reliable urine screening device would eliminate the need to perform quantitative culture on urine samples that contained insignificant numbers (i.e., less than 10,000 CFU/ml) and the generation of a final “negative” culture report within several hours of specimen receipt. This report reviews the reliability of various urine-screening methods and instruments in identifying urine samples that contain significant bacteriuria.

Bronchial inflammation and colonization in patients with clinically stable bronchiectasis.

To evaluate the bronchial inflammatory response and its relationship to bacterial colonization in bronchiectasis, we performed a bronchoalveolar lavage (BAL) in 49 patients in stable clinical condition and in nine control subjects. BAL was processed for differential cell count, quantitative bacteriologic cultures, and measurement of inflammatory mediators. An increase was observed in the percentage of neutrophils (37 [0 to 98]) (median[range]) versus 1[0 to 4]%, p = 0.01), in the concentration of elastase (90.5 [8 to 2,930] versus 34 [9 to 44], p = 0.03), myeloperoxidase (9.1 [0 to 376] versus 0.3 [0.1 to 1.4], p = 0.01), and in the levels of TNF-alpha (4 [0 to 186] versus 0 [0 to 7], p = 0.03), IL-8 (195 [0 to 5,520] versus 3 [0 to 31], p = 0.001), and IL-6 (6 [0 to 115] versus 0 [0 to 3], p = 0.001) in patients with bronchiectasis compared with control subjects. Noncolonized patients showed a more intense bronchial inflammatory reaction than did control subjects. This inflammatory reaction was exaggerated in patients colonized by microorganisms with potential pathogenicity (MPP), with a clear relationship with the bronchial bacterial load. Patients with bronchiectasis showed a slight systemic inflammatory response, with poor correlations between systemic and bronchial inflammatory mediators, suggesting that the inflammatory process was mostly compartmentalized. We conclude that patients with bronchiectasis in a stable clinical condition present an active neutrophilic inflammation in the airways that is exaggerated by the presence of MPP, and the higher the bacterial load the more intense the inflammation.

Prostatitis: US perspective

The diagnosis and management of prostatitis syndromes is a challenge to the clinician. Careful history and examination of the prostate fluid and quantitative segmented bacteriologic cultures will lead to proper categorization into the recognized forms of the prostatitis syndrome. Antimicrobial therapy is effective in the majority of men with acute and chronic bacterial prostatitis (CBP). Fluoroquinolone agents appear to have an increasingly important role in this regard, although a randomized, prospective, double-blind study is still lacking. Alpha-1-selective blocking agents may relieve symptomatology of chronic pelvis pain syndrome (CPPS). Other non-prostatic sources of voiding symptoms should be sought and ruled out, especially malignancy or inflammatory disorders.

A pilot study on bacterial viability in acne. Assessment using dual flow cytometry on microbials present in follicular casts and comedones.

Antibiotic therapy is one of the main methods of acne treatment, however, bacterial resistance is on the rise and can affect the treatment outcome. Quantitative bacteriologic cultures are the gold standard methodology for the assessment of such a problem; however, certain important biological aspects remain uncovered. The purpose of this study was to compare the antibacterial activity of minocycline and lymecycline in sebaceous follicle infundibula and comedones of acne patients. We used a recently introduced flow cytometric method, allowing a distinction to be made between viable, injured (presumably resistant), and dead microorganisms. Minocycline (100 mg) proved to be superior to lymecycline (600 mg) in abating the microflora harboring in the sebaceous follicles of acne patients. The dissimilar bioavailability and antimicrobial efficacy between the two bacteriostatic agents may impart different clinical efficacy.

Mucosa-associated bacterial flora of the human colon.

Biopsy samples of mucosa were taken during colonoscopy from the proximal colon and rectum of 12 patients, six with ulcerative colitis (UC) and six with non-inflammatory conditions. After anaerobic transport to the laboratory, biopsy specimens were examined by quantitative bacteriological culture on selective and non-selective media for total aerobic count, total anaerobic count, Bacteroides spp., lactobacilli, bifidobacteria and asaccharolytic, lactic acid producers. Isolates of the genus Bacteroides were identified to species level. Counts from proximal colonic and rectal biopsy samples in the same patient were not significantly different. Viable aerobic counts (aerobes and facultative organisms) ranged from 2.4 x 10(3) to 1.3 x 10(6) cfu/sample biopsy (5.6 mg) and total anaerobic counts were 10-10(2) times higher at (1.4 x 10(5))-(3 x 10(7)) cfu/sample. Bacteroides spp. predominated at both sites (range 8.6 X 10(4) to 1.4 x 10(7) cfu/sample), comprising 66% of total counts from proximal colon (range in individual patients 31-80%) and 68.5% from rectum (range 38-91%). Lactobacilli were isolated from eight biopsy samples from five patients, counts ranging from 3.6 X 10(2) to 1 X 10(5) cfu/sample; bifidobacteria were isolated from both sites from 10 of the 12 patients, counts ranging from 50 to 1.8 x 10(6) cfu/sample. From the 24 biopsy samples, 235 isolates representing 11 species of Bacteroides were identified. For any individual patient, only a few species (2-7; mean 4.4) of Bacteroides were found, with just one or two species predominating. B. vulgatus was cultured from both samples of seven patients (where it was the major isolate in four) and from single samples of two others; B. fragilis was cultured from both sites in six patients, being the major isolate in one patient and second commonest in three, but was not detected in the other six; the majority of other isolates were B. merdae/distasonis, B. ovatus, B. thetaiotaomicron and B. uniformis. B. thetaiotaomicron was isolated from both biopsy samples in all three UC patients with active inflammation (16 of the 60 isolates from these patients) but from only four of the other 18 samples from non-inflamed colonic mucosa (nine of 175 isolates).

Safety, efficacy, and duration of immunity induced in swine by use of an avirulent live Salmonella choleraesuis-containing vaccine

SUMMARY An avirulent live Salmonella choleraesuis culture (SC-54) was evaluated for use as an effective vaccine in preventing salmonellosis caused by S choleraesuis in pigs. Eighty-two pigs, 3 to 4 weeks old, were randomly assigned to 1 of 2 treatment groups, which were designated as either vaccinates or controls. After vaccination, all pigs were examined for fecal shedding of S choleraesuis, rectal temperature, and 10 clinical variables. Significant difference was not detected between vaccinated and nonvaccinated pigs for 14 days (phase I) after intranasal administration of the vaccine. Efficacy and duration of immunity were examined by intranasally challenge exposing respective pigs from either treatment group with a virulent field isolate of S choleraesuis at 2, 8, or 20 weeks after vaccination (phases II-IV). Pigs were again evaluated for 14 days after challenge exposure, and 10 clinical variables and rectal temperature were monitored. Surviving pigs were euthanatized and evaluated for gross lesions, and samples of 7 organs were collected. These organ samples were homogenized, and level of S choleraesuisS choleraesuis infection was determined. After virulent challenge exposure during phases II-IV, the clinical status of the SC-54 vaccinates was significantly (P &lt; 0.05) superior to that of nonvaccinates for rectal temperature, feces consistency, behavior, appetite, body condition, and mean score for the 10 clinical variables. Quantitative bacteriologic culture of the tonsil, lung, liver, spleen, mesenteric lymph nodes, ileum, and colon samples indicated consistent reduction of organ colonization in vaccinates; bacteria numbers in the mesenteric lymph nodes, lungs, and ileum were significantly (P &lt; 0.05) reduced. Gross lesions in pigs indicated reduction of penumonia in vaccinates. Pigs also had consistent weight gain throughout phases of the study after challenge exposure although the differences were not significant conclusion single intranasally administered dose SC-54 given to 3- to 4- week old pigs proved be safe and efficacious and to provide protection to pigs least 20 weeks after initial vaccination.

Use of rifabutin in treatment of systemic Mycobacterium paratuberculosis infection in mice

BALB/c mice were infected intraperitoneally with Mycobacterium paratuberculosis and, after allowing the infection to progress for 30 days, were treated with rifabutin at 0, 12.5, 25, and 50 mg/kg of body weight. Rifabutin was administered in drinking water under conditions of water deprivation, whereby the entire daily dose was delivered within a 1-h period. Animals were killed at biweekly intervals from time zero of treatment to 180 days. Spleens and livers from each animal were examined by quantitative bacteriologic culture and histopathology. Restricted water availability was found to be a viable alternative to daily gavage for single-dose bolus administration. Infection, as assessed by bacterial counts, was reduced only in animals that received 50 mg of rifabutin per kg. In these animals, bacterial counts in the liver and spleen were reduced from 7.2 x 10(5) +/- 4.1 x 10(4) and 6.5 x 10(5) +/- 4.1 x 10(4) to 3.0 x 10(3) +/- 1.8 x 10(2) and 3.1 x 10(3) +/- 2.2 x 10(2), respectively, over the 6-month treatment period. Rifabutin may be an appropriate chemotherapeutic drug for long-term treatment of M. paratuberculosis infection and should be considered in any multidrug regimen.