Prospective comparison of prostatic aspirate culture and cystocentesis urine culture for detection of bacterial infection in dogs with prostatic neoplasia

OBJECTIVE

The purpose of this study was to determine whether prostatic aspirate culture is a superior method to detect infection compared to culture of urine collected by cystocentesis in dogs with prostatic neoplasia.

MATERIALS AND METHODS

A prospective study was conducted and dogs with suspected or confirmed prostatic neoplasia were enrolled. Urinalysis was done and culture and antimicrobial susceptibility testing was performed on paired urine and prostatic aspirate samples collected at a single timepoint.

RESULTS

Ten dogs with prostatic neoplasia were enrolled. All dogs had one or more clinical sign consistent with lower urinary tract disease. One dog (10%) had a positive urine culture, but negative prostatic aspirate culture, one dog (10%) had a positive prostatic aspirate culture, but negative urine culture, and one dog (10%) had both positive urine and prostatic aspirate cultures. Using prostatic aspirate culture as the reference standard, urine culture had a sensitivity for detecting infection of 87.5% (95% confidence interval 52.9 to 99.4) and specificity of 50% (92.6 to 97.4) in this population of dogs.

CLINICAL SIGNIFICANCE

Positive cultures were uncommon with both culture collection methods. Study results did not identify prostatic aspirate culture to be a more sensitive method of detecting prostatic infection than urine culture collected by cystocentesis in these dogs with prostatic neoplasia.

Use of quantitative real-time PCR to determine viability of Streptococcus equi subspecies equi in respiratory secretions from horses with strangles

BACKGROUND

In recent years, molecular approaches have been able to characterise the viability of equine upper respiratory tract pathogens using absolute molecular quantitation as well as detection of transcripts for virulence genes.

OBJECTIVES

The objective of this study was to investigate molecular surrogates for S. equi subspecies equi (S. equi) viability in biological samples from horses with strangles.

STUDY DESIGN

Retrospective cross-sectional study.

METHODS

S. equi culture-positive and culture-negative upper airway secretions were assessed by qPCR at the genomic (gDNA) and complimentary DNA (cDNA) level for various target genes (SeM, SEQ2190, eqbE and szpSe). Absolute quantitation was performed using standard curves, and the results were expressed as number of S. equi target genes per μl of gDNA or cDNA. Additionally, the presence or absence of S. equi gene expression for the various target genes was assessed and compared with the culture results.

RESULTS

While all 21 culture-positive samples tested S. equiqPCR positive, up to 43.7 and 18.9% of 64 culture-negative samples tested qPCR positive at the gDNA and cDNA level, respectively. Significant differences in absolute quantitation for S. equi at the gDNA level were found between culture-positive and culture-negative samples. When absolute quantitation of S. equi target genes at the gDNA level was assessed with the presence or absence of transcripts, there was a significantly higher S. equi target gene number in samples with expression of transcripts compared with samples with no expression of transcripts.

MAIN LIMITATIONS

The lack of standardisation of samples collected in the field and the delay from sample collection to samples processing may have negatively affected the cultivability of S. equi and mRNA quality.

CONCLUSIONS

Molecular viability for S. equi can be investigated by determining absolute quantitation and/or by detecting mRNA for specific target genes. However, veterinarians have to be cautioned that any qPCR-positive result for S. equi needs to be taken seriously and trigger biosecurity protocols aimed at reducing spread.

Evaluation of the Live Biotherapeutic Product, Asymptomatic Bacteriuria Escherichia coli 2-12, in Healthy Dogs and Dogs with Clinical Recurrent UTI

Background

Antimicrobial resistance is an emerging problem.

Hypothesis/Objective

To investigate the safety and efficacy of a live biotherapeutic product, ASB E. coli 2‐12 for UTI treatment.

Animals

Six healthy research dogs; nine client‐owned dogs with recurrent UTI.

Methods

Prospective noncontrolled clinical trial. For safety data, research dogs were sedated, a urinary catheter was inserted into the bladder; 10¹⁰CFU/mL of ASB E. coli 2‐12 was instilled. Urine was cultured on days 1, 3, and 8 post‐instillation and dogs were observed for lower urinary tract signs (LUTS). For client‐owned dogs, ASB E. coli 2‐12 was instilled similarly and urine cultures analyzed on days 1, 7, and 14 days postinstillation.

Results

No LUTS were noted in any of the 6 research dogs after ASB E. coli 2‐12 infusion. Pulse field gel electrophoresis (PFGE) studies confirmed the bacterial strains isolated matched that ASB E. coli 2‐12 strain. Four of the nine client‐owned dogs had complete or nearly complete clinical cures by day 14. Of these four dogs, 3 also had microbiologic cures at day 14; one of these dogs had subclinical bacteriuria (in addition to ASB E. coli 2‐12). Three of these four dogs had ASB E. coli 2‐12 isolated from their urine at day 14. With the exception of mild, temporary, self‐limiting, hyporexia in two dogs on the day of biotherapeutic administration, there were no major adverse effects.

Conclusions and Clinical Importance

These results suggest ASB E. coli 2‐12 is safe and should be investigated in a larger controlled study evaluating clinical UTI in dogs.

Fatal Streptococcus canis Infections in Intensively Housed Shelter Cats

Three independent, fatal outbreaks of Streptococcus canis infection occurred in a 2-year period in shelter cats. The outbreaks occurred in Northern California (Yolo County), Southern California (Kern County), and North Carolina (Guilford County). An estimation of the affected population is >150 cats among 3 affected shelters, with a mortality rate of up to 30%. Among 20 cats submitted for necropsy there were 2 distinct pathologic presentations. The first (shelters 1 and 2) was skin ulceration and chronic respiratory infection that progressed, in some cats, to necrotizing sinusitis and meningitis. The second (shelter 3) was rapid progression from necrotizing fasciitis with skin ulceration to toxic shock-like syndrome, sepsis, and death. S canis was the sole pathogen identified in most cases. Whether hypervirulent S canis strains exist is unknown; there is little understanding of how these bacteria cause invasive disease in cats.

Bronchoscopy, Imaging, and Concurrent Diseases in Dogs with Bronchiectasis: (2003-2014)

Background

Bronchiectasis is a permanent and debilitating sequel to chronic or severe airway injury, however, diseases associated with this condition are poorly defined.

Objective

To evaluate results of diagnostic tests used to document bronchiectasis and to characterize underlying or concurrent disease processes.

Animals

Eighty‐six dogs that had bronchoscopy performed and a diagnosis of bronchiectasis.

Methods

Retrospective case series. Radiographs, computed tomography, and bronchoscopic findings were evaluated for features of bronchiectasis. Clinical diagnoses of pneumonia (aspiration, interstitial, foreign body, other), eosinophilic bronchopneumopathy (EBP), and inflammatory airway disease (IAD) were made based on results of history, physical examination, and diagnostic testing, including bronchoalveolar lavage fluid analysis and microbiology.

Results

Bronchiectasis was diagnosed in 14% of dogs (86/621) that had bronchoscopy performed. Dogs ranged in age from 0.5 to 14 years with duration of signs from 3 days to 10 years. Bronchiectasis was documented during bronchoscopy in 79/86 dogs (92%), thoracic radiology in 50/83 dogs (60%), and CT in 34/34 dogs (100%). Concurrent airway collapse was detected during bronchoscopy in 50/86 dogs (58%), and focal or multifocal mucus plugging of segmental or subsegmental bronchi was found in 41/86 dogs (48%). Final diagnoses included pneumonia (45/86 dogs, 52%), EBP (10/86 dogs, 12%) and IAD (31/86 dogs, 36%). Bacteria were isolated in 24/86 cases (28%), with Streptococcus spp, Pasteurella spp, enteric organisms, and Stenotrophomonas isolated most frequently.

Conclusions and Clinical Importance

Bronchiectasis can be anticipated in dogs with infectious or inflammatory respiratory disease. Advanced imaging and bronchoscopy are useful in making the diagnosis and identifying concurrent respiratory disease.

Pneumonia Caused by Klebsiella spp. in 46 Horses

BACKGROUND

Klebsiella spp. are implicated as a common cause of bacterial pneumonia in horses, but few reports describe clinical presentation and disease progression.

HYPOTHESIS/OBJECTIVES

To describe the signalment, clinicopathologic data, radiographic and ultrasonographic findings, antimicrobial susceptibility, outcome, and pathologic lesions associated with Klebsiella spp. pneumonia in horses.

ANIMALS

Forty-six horses from which Klebsiella spp. was isolated from the lower respiratory tract.

METHODS

Retrospective study. Medical records from 1993 to 2013 at the William R. Pritchard Veterinary Medical Teaching Hospital, University of California, Davis were reviewed. Exact logistic regression was performed to determine if any variables were associated with survival to hospital discharge.

RESULTS

Survival in horses <1 year old was 73%. Overall survival in adults was 63%. For adults in which Klebsiella pneumoniae was the primary isolate, survival was 52%. Mechanical ventilation preceded development of pneumonia in 11 horses. Complications occurred in 25/46 horses, with thrombophlebitis and laminitis occurring most frequently. Multi-drug resistance was found in 47% of bacterial isolates. Variables that significantly impacted survival included hemorrhagic nasal discharge, laminitis, and thoracic radiographs with a sharp demarcation between marked caudal pulmonary alveolar infiltration and more normal-appearing caudodorsal lung.

CONCLUSIONS AND CLINICAL IMPORTANCE

Klebsiella spp. should be considered as a differential diagnosis for horses presenting with hemorrhagic pneumonia and for horses developing pneumonia after mechanical ventilation. Multi-drug resistance is common. Prognosis for survival generally is fair, but is guarded for adult horses in which K. pneumoniae is isolated as the primary organism.

Bacterial urinary tract infections associated with transitional cell carcinoma in dogs

Background

Urinary tract infections (UTI) are believed to be common in dogs with transitional cell carcinoma (TCC), but incidence and contributing factors have not been reported.

Objectives

To determine the frequency and bacterial agents associated with UTI in dogs with TCC and define contributing factors.

Animals

Eighty‐five dogs with a history of urogenital TCC undergoing treatment with chemotherapy that had at least 1 urine culture performed.

Methods

Medical records and culture results were retrospectively reviewed and ultrasound images were reviewed when available. Clinical factors were evaluated statistically for association with positive culture.

Results

Fifty‐five percent (47/85) of dogs had at least 1 positive culture during the course of treatment. Female dogs (80%, 40/50) were more likely than male dogs (29%, 10/35) to have at least 1 positive culture. Ultrasound examination determined that female dogs were more likely to have urethral (74%, 31/42) or trigonal tumor involvement (71%, 30/42) compared to male dogs (32%, 9/28 and 43%, 12/28, respectively). The most commonly isolated organisms were Staphylococcus spp. (23.9%, 29/121) and Escherichia coli (19.8%, 24/121). Dogs with urethral involvement of TCC were significantly more likely to have at least 1 positive culture than dogs without urethral involvement (75%, 30/40 versus 30%, 9/30).

Conclusions

Urinary tract infection is common in dogs with TCC highlighting the importance of regular monitoring for bacterial cystitis in dogs with TCC. In addition, clinical factors such as tumor location and sex may be predictive of positive culture and can help clinicians assess the risk of UTI.

Minimum inhibitory concentrations of equine Corynebacterium pseudotuberculosis isolates (1996-2012)

Background

Few studies report the minimum inhibitory concentrations for antimicrobials against equine Corynebacterium pseudotuberculosis isolates.

Hypothesis/Objectives

To evaluate trends in the in vitro activities of 20 antimicrobials against equine Corynebacterium pseudotuberculosis isolates from 1996 to 2012 and to determine if a relationship exists between the minimum inhibitory concentration (MIC) and location of the abscess.

Animals

Corynebacterium pseudotuberculosis isolates from 196 horses with naturally occurring disease.

Methods

Retrospective and cross‐sectional design. Medical records were reviewed to obtain clinical and MIC data. Minimum inhibitory concentrations were determined by the microdilution technique. The MIC results over 3 periods were compared (1996–2001, 2002–2006, 2007–2012).

Results

The MIC₉₀ values for clinically relevant antimicrobials were as follows: chloramphenicol ≤4 μg/mL, enrofloxacin ≤0.25 μg/mL, gentamicin ≤1 μg/mL, penicillin =0.25 μg/mL, rifampin ≤1 μg/mL, tetracycline ≤2 μg/mL, trimethoprim‐sulfamethoxazole (TMS) ≤0.5 μg/mL, ceftiofur =2 μg/mL, and doxycycline ≤2 μg/mL. There were no significant changes in MIC results over the study period. There was no relationship between MIC patterns and abscess location.

Conclusions and Clinical Importance

The MIC₅₀ and MIC₉₀ values of antimicrobials evaluated in this study for equine isolates of C. pseudotuberculosis did not vary over time. Abscess location was not associated with different MIC patterns in cultured isolates. Several commonly used antimicrobials are active in vitro against C. pseudotuberculosis in vitro.

Laser Capture Microdissection of Feline Streptomyces spp Pyogranulomatous Dermatitis and Cellulitis

Suspected Streptomyces spp infections were identified in 4 cats at UC Davis Veterinary Medical Teaching Hospital between 1982 and 2011. Three had ulcerated, dark red mycetomas involving the dermis, subcutis, and fascia with fistulous tracts and/or regional lymphadenopathy. One cat had pyogranulomatous mesenteric lymphadenitis. Granulomatous inflammation in all cats contained colonies of Gram-positive, non-acid-fast organisms. All 4 cats failed to respond to aggressive medical and surgical treatment and were euthanized. Laser capture microdissection (LCM) was used to selectively harvest DNA from the affected formalin-fixed, paraffin-embedded (FFPE) tissues. Cloned amplicons from LCM-derived tissue confirmed the presence of Streptomyces spp in the dermatitis cases. Amplicons from the remaining cat with peritoneal involvement aligned with the 16S ribosomal RNA gene for Actinomycetales. Usually considered a contaminant, Streptomyces spp can be associated with refractory pyogranulomatous dermatitis and cellulitis in cats with outdoor access. LCM is useful in the diagnosis of bacterial diseases where contamination may be an issue.

Salmonella Oranienburg isolated from horses, wild turkeys and an edible home garden fertilized with raw horse manure

In July 2010, a horse from a rural farm (Farm A) in coastal Northern California was diagnosed with Salmonella Oranienburg infection following referral to a veterinary hospital for colic surgery. Environmental sampling to identify potential sources and persistence of Salmonella on the farm was conducted from August 2010 to March 2011. Salmonella was cultured using standard enrichment and selective plating. Pure colonies were confirmed by biochemical analysis, serotyped and compared by pulsed-field gel electrophoresis (PFGE) analysis. A total of 204 clinical and environmental samples at Farm A were analysed, and Salmonella spp. was isolated from six of eight (75%) horses, an asymptomatic pet dog, two of seven (28.6%) water samples from horse troughs, nine of 20 (45%) manure storage pile composites, 16 of 71 (22.5%) wild turkey faeces and four of 39 (10.3%) soil samples from the family's edible home garden. Well water and garden vegetable samples and horse faecal samples from a neighbouring ranch were negative. S. Oranienburg with a PFGE pattern indistinguishable from the horse clinical strain was found in all positive sample types on Farm A. The investigation illustrates the potential for widespread dissemination of Salmonella in a farm environment following equine infections. We speculate that a recent surge in the wild turkey population on the property could have introduced S. Oranienburg into the herd, although we cannot rule out the possibility wild turkeys were exposed on the farm or to other potential sources of Salmonella. Findings from the investigation indicated that raw horse manure applied as fertilizer was the most likely source of garden soil contamination. Viable S. Oranienburg persisted in garden soil for an estimated 210 days, which exceeds the 120-day standard between application and harvest currently required by the National Organic Program. The study underscores the need to educate the public about potential food safety hazards associated with using raw animal manure to fertilize edible home gardens.

Pharmacokinetics of ceftiofur crystalline free acid after single and multiple subcutaneous administrations in healthy alpacas (Vicugna pacos)

Six adult male alpacas received one subcutaneous administration of ceftiofur crystalline free acid (CCFA) at a dosage of 6.6 mg/kg. After a washout period, the same alpacas received three subcutaneous doses of 6.6 mg/kg CCFA at 5-day intervals. Blood samples collected from the jugular vein before and at multiple time points after each CCFA administration were assayed for ceftiofur- and desfuroylceftiofur-related metabolite concentrations using high-performance liquid chromatography. Pharmacokinetic disposition of CCFA was analyzed by a noncompartmental approach. Mean pharmacokinetic parameters (± SD) following single-dose administration of CCFA were Cmax (2.7 ± 0.9 μg/mL); Tmax (36 ± 0 h); area under the curve AUC0→∞ (199.2 ± 42.1 μg·h/mL); terminal phase rate constant λz (0.02 ± 0.003/h); and terminal phase rate constant half-life t1/2λz (44.7 h; harmonic). Mean terminal pharmacokinetic parameters (±SD) following three administrations of CCFA were Cmax (2.0 ± 0.4 μg/mL); Tmax (17.3 ± 16.3 h); AUC0→∞ (216.8 ± 84.5 μg·h/mL); λz (0.01 ± 0.003/h); and t1/2λz (65.9 h; harmonic). The terminal phase rate constant and the Tmax were significantly different between single and multiple administrations. Local reactions were noted in two alpacas following multiple CCFA administrations.

Enteropathogenic bacteria in dogs and cats: diagnosis, epidemiology, treatment, and control

This report offers a consensus opinion on the diagnosis, epidemiology, treatment, and control of the primary enteropathogenic bacteria in dogs and cats, with an emphasis on Clostridium difficile, Clostridium perfringens, Campylobacter spp., Salmonella spp., and Escherichia coli associated with granulomatous colitis in Boxers. Veterinarians are challenged when attempting to diagnose animals with suspected bacterial-associated diarrhea because well-scrutinized practice guidelines that provide objective recommendations for implementing fecal testing are lacking. This problem is compounded by similar isolation rates for putative bacterial enteropathogens in animals with and without diarrhea, and by the lack of consensus among veterinary diagnostic laboratories as to which diagnostic assays should be utilized. Most bacterial enteropathogens are associated with self-limiting diarrhea, and injudicious administration of antimicrobials could be more harmful than beneficial. Salmonella and Campylobacter are well-documented zoonoses, but antimicrobial administration is not routinely advocated in uncomplicated cases and supportive therapy is recommended. Basic practices of isolation, use of appropriate protective equipment, and proper cleaning and disinfection are the mainstays of control. Handwashing with soap and water is preferred over use of alcohol-based hand sanitizers because spores of C. difficile and C. perfringens are alcohol-resistant, but susceptible to bleach (1:10 to 1:20 dilution of regular household bleach) and accelerated hydrogen peroxide. The implementation of practice guidelines in combination with the integration of validated molecular-based testing and conventional testing is pivotal if we are to optimize the identification and management of enteropathogenic bacteria in dogs and cats.

Pharmacokinetic-pharmacodynamic integration of orbifloxacin in Japanese quail (Coturnix japonica) following oral and intravenous administration

The pharmacokinetics of single-dose administration of orbifloxacin were determined in Japanese quail (Coturnix japonica) at dosages of 5 mg/kg intravenous (i.v. n = 12) and 7.5 mg/kg oral (p.o.; n = 5), 10 mg/kg p.o. (n = 5), 15 mg/kg p.o. (n = 12) and 20 mg/kg p.o. (n = 5) via HPLC. Orbifloxacin minimal inhibitory concentrations (MICs) against 22 microbial isolates from various bird species were performed to calculate pharmacodynamic surrogate markers. The concentration-time data were analyzed using a naïve pooled data (NPD) approach and compartmental and noncompartmental methods. Steady-state volume of distribution (Vd(ss)) and total body clearance (Cl) after i.v. administration were estimated to be 1.27 L/kg and 0.60 L/h·kg, respectively. Following 15 and 20 mg/kg p.o. dose, bioavailability was 102% and 117%, respectively. The harmonic mean of the corresponding terminal half-lives (T(1/2) λ(z) ) across all the dose groups was 1.71 h. The C(max) /MIC(90) and AUC(0∞24) /MIC(90) for the 15 and 20 mg/kg p.o. doses were ≥5.22 and ≥8.98, and ≥25.80 and ≥39.37 h, respectively. The results of this study suggest that 20 mg/kg orbifloxacin p.o. would be a rational daily dose to treat susceptible infections in Japanese quail not intended for food consumption. For more sensitive bacterial organisms, 15 mg/kg p.o. may also be effective.

A pregnant mouse model for bovine Tritrichomonas foetus infection

The economically important effects of Tritrichomonas foetus infection in cattle are abortion and infertility, yet there has not been an animal model to examine the parasite-host interactions during gestation. In this study, 5- and 7- to 8-week-old BALB/cAnNCr, BALB/cJ, and SCID/NCr mice on a BALB/c background were intravaginally infected with T. foetus. All BALB/cAnNCr and BALB/cJ mice, and 89% of SCID/NCr mice sustained infections for 13 weeks, if inoculated before 5 weeks of age. Infection rates were lower in all mouse strains inoculated at 7 weeks of age, although BALB/cAnNCr mice were significantly more susceptible than BALB/cJ or SCID/NCr mice. Vaginal bacterial flora did not account for the variation in mouse-strain susceptibility, although coagulase-negative staphylococci in vaginal flora were associated with failure of T. foetus to infect. As with infected cattle, T. foetus-specific vaginal immunoglobulin (Ig) G and IgA antibodies were elevated after infection. The number and viability of day-10 fetuses were reduced in mice infected at 5 weeks of age and bred 12 weeks after infection. Lesions in pregnant and nonpregnant infected mice, including suppurative and eosinophilic vaginitis; cervicitis; endometritis with distension of the uterine lumen; endometrial ulceration; and glandular ectasia, with neutrophils in the glandular lumen and loss of gland epithelium, were similar to those in cattle. The decidua and placenta were multifocally necrotic. Immunohistochemistry demonstrated trichomonads in vaginal folds and uterine glands, and adjacent to fetal tissues. In summary, experimentally infected BALB/cAnNCr mice showed many pathologic similarities to cattle and may serve as a model to study host-trichomonad interactions.

Prevalence and characterization of Salmonella spp. among marine animals in the Channel Islands, California

Salmonella enterica is a zoonotic pathogen that has been isolated from free-ranging marine mammals throughout the world, with animals in the Channel Islands of California (USA) showing the highest prevalence. The goal of this study was to determine prevalence, antimicrobial sensitivity and genetic similarity using pulsed-field gel electrophoresis (PFGE) of Salmonella in several non-domestic animal species on San Miguel and San Nicolas Islands. Fecal samples were collected from 90 California sea lion Zalophus californianus pups, 30 northern elephant seal Mirounga angustirostris pups and 87 western gulls Larus occidentalis in the Channel Islands and 59 adult male sea lions in Puget Sound, WA (USA). Salmonella were isolated, identified and serotyped, followed by antimicrobial susceptibility testing and PFGE. Of the California sea lion pups that were sampled on the islands, 21% (n = 19) were positive for Salmonella, whereas no adults males in Puget Sound were positive. Of the northern elephant seal pups sampled, 87% (n = 26) were harboring Salmonella. Only 9% (n = 8) of western gulls were shedding Salmonella, with one of these gulls harboring the only antimicrobial resistant isolate. The serotypes found in these animals were Enteritidis, Montevideo, Newport, Reading, and Saint Paul. The only serotype that showed variation on PFGE was Newport. The pinnipeds of the Channel Islands harbor Salmonella at a higher prevalence than pinnipeds from other geographic areas observed in previous studies. Researchers and veterinarians should exercise increased caution when working with these animals due to the zoonotic potential of Salmonella.

Salmonella spp., Vibrio spp., Clostridium perfringens, and Plesiomonas shigelloides in marine and freshwater invertebrates from coastal California ecosystems

The coastal ecosystems of California are highly utilized by humans and animals, but the ecology of fecal bacteria at the land-sea interface is not well understood. This study evaluated the distribution of potentially pathogenic bacteria in invertebrates from linked marine, estuarine, and freshwater ecosystems in central California. A variety of filter-feeding clams, mussels, worms, and crab tissues were selectively cultured for Salmonella spp., Campylobacter spp., Escherichia coli-O157, Clostridium perfringens, Plesiomonas shigelloides, and Vibrio spp. A longitudinal study assessed environmental risk factors for detecting these bacterial species in sentinel mussel batches. Putative risk factors included mussel collection near higher risk areas for livestock or human sewage exposure, adjacent human population density, season, recent precipitation, water temperature, water type, bivalve type, and freshwater outflow exposure. Bacteria detected in invertebrates included Salmonella spp., C. perfringens, P. shigelloides, Vibrio cholerae, Vibrio parahaemolyticus, and Vibrio alginolyticus. Overall, 80% of mussel batches were culture positive for at least one of the bacterial species, although the pathogens Campylobacter, E. coli-O157, and Salmonella were not detected. Many of the same bacterial species were also cultured from upstream estuarine and riverine invertebrates. Exposure to human sewage sources, recent precipitation, and water temperature were significant risk factors for bacterial detection in sentinel mussel batches. These findings are consistent with the hypothesis that filter-feeding invertebrates along the coast concentrate fecal bacteria flowing from land to sea and show that the relationships between anthropogenic effects on coastal ecosystems and the environmental niches of fecal bacteria are complex and dynamic.

Partial genome sequencing of Rhodococcus equi ATCC 33701

Preliminary analysis of a partial (30% coverage) genome sequence of Rhodococcus equi has revealed a number of important features. The most notable was the extent of the homology of genes identified with those of Mycobacterium tuberculosis. The similarities in the proportion of genes devoted to fatty acid degradation and to lipid biosynthesis was a striking but not surprising finding given the relatedness of these organisms and their success as intracellular pathogens. The rapid recent improvement in understanding of virulence in M. tuberculosis and other pathogenic mycobacteria has identified a large number of genes of putative or proven importance in virulence, homologs of many of which were also identified in R. equi. Although R. equi appears to have currently unique genes, and has important differences, its similarity to M. tuberculosis supports the need to understand the basis of virulence in this organism. The partial genome sequence will be a resource for workers interested in R. equi until such time as a full genome sequence has been characterized.

Virulence plasmid of Rhodococcus equi contains inducible gene family encoding secreted proteins

Rhodococcus equi causes severe pyogranulomatous pneumonia in foals. This facultative intracellular pathogen produces similar lesions in immunocompromised humans, particularly in AIDS patients. Virulent strains of R. equi bear a large plasmid that is required for intracellular survival within macrophages and for virulence in foals and mice. Only two plasmid-encoded proteins have been described previously; a 15- to 17-kDa surface protein designated virulence-associated protein A (VapA) and an antigenically related 20-kDa protein (herein designated VapB). These two proteins are not expressed by the same R. equi isolate. We describe here the substantial similarity between VapA and VapB. Moreover, we identify three additional genes carried on the virulence plasmid, vapC, -D, and -E, that are tandemly arranged downstream of vapA. These new genes are members of a gene family and encode proteins that are approximately 50% homologous to VapA, VapB, and each other. vapC, -D, and -E are found only in R. equi strains that express VapA and are highly conserved in VapA-positive isolates from both horses and humans. VapC, -D, and -E are secreted proteins coordinately regulated by temperature with VapA; the proteins are expressed when R. equi is cultured at 37 degrees C but not at 30 degrees C, a finding that is compatible with a role in virulence. As secreted proteins, VapC, -D, and -E may represent targets for the prevention of rhodococcal pneumonia. An immunologic study using VapA-specific antibodies and recombinant Vap proteins revealed no evidence of cross-reactivity despite extensive sequence similarity over the carboxy terminus of all four proteins.

Extensor tendon: anatomy, injury, and reconstruction

Although seemingly simple in its anatomy and function, the extensor mechanism of the hand is actually a complex set of interlinked muscles, tendons, and ligaments. A thorough understanding of the extensor anatomy is required to understand the consequences of injury at various levels. Reconstructive options must restore normal function. Whereas primary repair of anatomic structures is frequently possible in acute injury, it is rarely possible in chronic situations. Technically exacting procedures may be necessary to restore function.

Immunity to Rhodococcus equi

Rhodococcal pneumonia is an important, life threatening disease of foals and immunosuppressed humans. Increased knowledge of the mechanisms of protective immunity are required in order to develop an effective immunoprophylaxis strategy for horses and immunotherapeutic regiments for people. Both humoral and cellular components of the immune system may be involved in immune clearance of R. equi. The susceptibility of foals less than 4-6 months of age is postulated to reflect waning maternal antibody, and passive transfer of hyperimmune plasma can provide protection on endemic farms. However, effective clearance is likely to require appropriate cellular responses, including the secretion of cytokines. In murine models, both CD4+ and CD8+ T lymphocytes can reduce bacterial counts in the lung. CD4+ cells appear to be both required and sufficient, and IFN-gamma is a primary mediator. Clearance appears to be a type 1 immune response while type 2 responses may lead to a failure to clear and lesion development. It remains to be determined how the cellular immunity experiments reported in mice relate to horses and humans. Likewise, the role of specific R. equi antigens in protective immunity has not been determined.

Ileocecal intussusception corrected by resection within the cecum in two horses

Irreducible ileocecal intussusceptions pose a difficult surgical problem. Strangulating ileocecal intussusceptions involving the ileum and jejunum were identified in 2 horses undergoing exploratory laparotomy because of colic. Surgical correction in both horses was achieved by amputation of the ileocecal intussusception from within the cecal lumen, via typhlotomy. The inverted ileal stump was blindly stapled near the ileocecal orifice after pulling the intussusceptum into the cecum. A jejunocecostomy was performed to reestablish intestinal continuity.

Clinical examination of the respiratory system

Aspects of a detailed examination of the respiratory system of the horse with suspected respiratory system disease are described. This review includes discussions of the terminology of signs associated with respiratory system disease; radiographic examination of the upper and lower airways and thorax; nuclear scintigraphy; percutaneous and endoscopic tracheal aspiration; bronchoalveolar lavage; electromyography; blood gas analysis; and pleuroscopy and pleural fluid examination.