Meticillin-resistant Staphylococcus aureus in a veterinary orthopaedic referral hospital: staff nasal colonisation and incidence of clinical cases

OBJECTIVES: To evaluate staff nasal colonisation with meticillin-resistant Staphylococcus aureus in a veterinary orthopaedic referral hospital, and its effect on the occurrence of meticillin-resistant Staphylococcus aureus-associated postoperative wound complications in orthopaedic and spinal surgical patients. METHODS: Nasal bacterial swabs were collected from veterinary staff and environmental surfaces swabbed at six monthly intervals for meticillin-resistant Staphylococcus aureus monitoring over an 18 month period. The incidence of meticillin-resistant Staphylococcus aureus-associated postoperative wound complications of two veterinary orthopaedic surgeons was reviewed for a period when one was positive for nasal meticillin-resistant Staphylococcus aureus. RESULTS: Meticillin-resistant Staphylococcus aureus was isolated from a maximum of two out of 10 staff on each occasion. The persistently infected clinician was primary surgeon in 180 cases, of which four developed meticillin-resistant Staphylococcus aureus-associated wound complications. None of 141 operations led by the other surgeon developed meticillin-resistant Staphylococcus aureus-associated complications. This difference is not statistically significant (P=0.0974). The 95 per cent confidence interval for this odds ratio was 0.83 to 44.0. Meticillin-resistant Staphylococcus aureus resistance patterns of the human nasal isolates and three of four wound-associated isolates were similar. CLINICAL SIGNIFICANCE: Veterinary workers are at increased risk for meticillin-resistant Staphylococcus aureus colonisation, so it is likely that many veterinary patients are treated by meticillin-resistant Staphylococcus aureus-positive staff. Nasal colonisation of veterinary surgeons with meticillin-resistant Staphylococcus aureus appears to present only a small risk to their patients when appropriate infection control procedures are followed.     

Surgical treatment of a vertebral fracture associated with a haematogenous osteomyelitis in a dog.

A seven-month-old Rottweiler was referred for a diagnosed femoral neck fracture and a suspected vertebral fracture. The simplified neurological examination revealed an acute paraplegia. A discospondyilitis associated with a pathologic fracture of Th11 and a spinal compression, and a haematogenous epiphysitis of the femoral neck were diagnosed based on radiographic and computed tomographic examinations. The vertebral fracture was stabilised using screws and polymethylmetacrylate with gentamycin by a lateral intercostal approach. The dog was able to walk seven days later. A femoral head and neck ostectomy was performed two weeks later. Staphylococcus intermedius was isolated from both sites, which confirmed the diagnosis. The dog was treated with cephalexin (30 mg/kg/d) for six weeks. A telephone interview with owners indicated that no more clinical signs were present four months after the second surgery. Discospondylitis associated with haematogenous osteomyelitis has only been reported in two cases. Paraplegia is an unusual clinical presentation for discospondylitis. The lateral approach (which allowed a direct access to the infected site) and the technique (screws associated with antibiotic-impregnated cement) are unique for surgical treatment of discospondylitis. Although applying cement to an infected area may pose a risk, antibiotic-loaded cement is successfully used in the treatment of chronic osteomyelitis in humans.     

Canine superficial bacterial folliculitis: Current understanding of its etiology,diagnosis and treatment

Superficial bacterial folliculitis (SBF) is more common in the dog than other mammalian species. Until recently, a successful outcome in cases of canine SBF was possible by administering a potentiated amoxicillin, a first generation cephalosporin or a potentiated sulfonamide. Unfortunately, this predictable susceptibility has changed, because methicillin resistant Staphylococcus pseudintermedius (MRSP) and Staphylococcus aureus (MRSA) are becoming more prevalent in canine SBF cases. The increasing frequency of multidrug resistance complicates the selection of antimicrobial therapy. Antimicrobial agents that were once rarely used in cases of canine SBF, such as amikacin, rifampicin and chloramphenicol, are becoming the drugs of choice, based on bacterial culture and susceptibility testing. Furthermore, changes in antimicrobial susceptibility have helped to re-emphasize the importance of a multimodal approach to treatment of the disease, including topical therapy. Due to the increasing frequency of identification of highly resistant Staphylococcus spp., topical antimicrobial therapy, including the use of diluted sodium hypochlorite (bleach), is becoming necessary to successfully treat some cases of canine SBF. Other important antiseptics that can be used include chlorhexidine, benzoyl peroxide, ethyl lactate, triclosan and boric acid/acetic acid. This review discusses the diagnostic and therapeutic management of canine SBF, with a special emphasis on treating methicillin resistant staphylococcal infections.     

Prevalence and distribution of meticillin-resistant Staphylococcus aureus within the environment and staff of a university veterinary clinic

O bjectives : To characterise the distribution of meticillin-resistant Staphylococcus aureus within the environment of a university small animal hospital and compare this with the distribution among staff.
M ethods : Samples were collected from 140 environmental sites and the anterior nares of 64 staff members at the University of Glasgow Small Animal Hospital on a single day (d1). Sixty of the environmental sites were resampled 14 days later (d14).
R esults : Meticillin-resistant S aureus was isolated from two of 140 (1·4 per cent; 95 per cent confidence interval: 1·7 to 5·1) environmental sites on d1 and one of 60 (1·7 per cent; 95 per cent confidence interval: 0·4 to 8·9) on d14. Two of the 64 staff sampled were positive for meticillin-resistant S aureus (3·1 per cent; 95 per cent confidence interval: 0·4 to 8·4).
C linical S ignificance : A lower prevalence of meticillin-resistant S aureus was observed in the environment than previously reported. The location, relatedness between isolates and the presence of Panton-Valentine leucocidin indicates that the source of the environmental meticillin-resistant S aureus was most likely to have been human rather than animal in these cases. This study presents important information regarding the potential source and distribution of meticillin-resistant S aureus within veterinary hospital environments and highlights potential variability of prevalence of meticillin-resistant S aureus within and between veterinary institutions.     

Surgical treatment of lumbosacral instability caused by discospondylitis in four dogs

OBJECTIVE: To describe a surgical technique involving distraction and stabilization of the lumbo-sacral vertebral segment using an external skeletal fixator in dogs with lumbosacral instability caused by discospondylitis. STUDY DESIGN: Retrospective clinical study. ANIMALS: Four client-owned dogs. METHODS: Medical records of all dogs diagnosed with discospondylitis from 1994 to 1997 were identified and reviewed. Four dogs with lumbosacral discospondylitis requiring surgical treatment were then specifically studied. Surgical technique, clinical signs, preoperative diagnostic investigation, radiographic findings, and the results of short-term and long-term reevaluations were recorded. RESULTS: Twelve dogs with discospondylitis were identified, 4 of which had lumbosacral discospondylitis. These 4 dogs underwent surgical distraction and stabilization because they failed to respond to medical treatment. Three dogs received a cancellous bone graft between L7 and S1 and had rapid interbody fusion of this vertebral segment. The dog that did not receive a graft did not have interbody fusion at the time of fixator removal. This did not affect the final clinical outcome. Lumbosacral pain and neurological deficits present before surgery rapidly subsided after the procedure. All dogs received concurrent antibiotic treatment for a minimum of 4 weeks. All dogs were clinically normal at the time of fixator removal and all continued to do well during the follow-up period (8-48 months; mean, 27.5 months). CONCLUSION AND CLINICAL RELEVANCE: Lumbosacral discospondylitis may not respond well to conservative treatment because of the mobility of the affected space. Surgical treatment involving distraction and stabilization to obtain intervertebral fusion is very effective in treating lumbosacral instability caused by discospondylitis.     

抑制奶牛乳房炎源金黄色葡萄球菌的乳酸菌的筛选

为获得抑制奶牛乳房炎源金黄色葡萄球菌(S. aureus)的乳酸菌(LAB),本研究从新疆巴音布鲁克牧区鲜牛乳和哈萨克族乳制品奶疙瘩样品中分离培养LAB,通过传统的分离鉴定与16S rDNA基因序列测序相结合的方法鉴定LAB种类,同时以临床奶牛乳房炎源金黄色葡萄球菌S. aureus N2为指示菌,采用双层琼脂扩散法检测分离株的抑菌能力。通过测定生长曲线确定分离株的生长稳定期,进而利用硫酸铵沉淀法透析提取稳定期内分离株的细菌素,并检测其细菌素抑菌效价。结果显示:从样品中筛选获得5株能够抑制指示菌生长的LAB,分别为希氏乳杆菌、干酪乳杆菌、粪肠球菌、戊糖片球菌和乳酸乳球菌亚种。生长规律曲线表明20 h^30 h为5株LAB的稳定期,此期培养液pH值维持在3.8~4.5。从培养20 h的5株LAB上清液中提取到了细菌素,经检测其具有抑菌活性,抑菌效价分别为457 IU/mL、1 023 IU/mL、676 IU/mL、1 862 IU/mL和1 023 IU/mL。本研究结果表明5株LAB通过在生长稳定期内维持较低酸性环境(pH<4.5),代谢产生细菌素对乳房炎源S. aureus发挥抑制生长作用。本研究为S. aureus性奶牛乳房炎的生物防治提供了实验依据。     

Surgical treatment of lumbosacral discospondylitis by a distraction-fusion technique

Lumbosacral discospondylitis was diagnosed in three adult dogs by radiography and the isolation of Staphylococcus aureus from the affected intervertebral space. The predominant clinical findings of severe spinal pain and marked hindlimb lameness suggested entrapment of the seventh lumbar spinal nerve roots. In addition, the presence of hindlimb ataxia, proprioceptive deficits, perineal analgesia and paresis of the tail were consistent with compression of the cauda equina. Despite medical therapy with analgesics, antibiotics and strict confinement the clinical and radiographic signs progressed. A lumbosacral distraction-fusion procedure was employed to decompress the spinal nerve roots and cauda equina and to stabilise the affected vertebrae. In all cases there was an immediate marked reduction in spinal pain and a long term resolution of clinical signs. In two cases the affected vertebrae progressively fused within four months. The third case required removal of the implants due to pin migration and breakage.     

Discospondylitis in association with an intra-abdominal abscess in a dog

An 11-year-old German shepherd dog cross was presented with a six-week history of weight loss and abdominal distension. A diagnosis of abdominal abscess and discospondylitis was made. The dog responded to surgical excision of the abscess and conservative medical treatment for discospondylitis.     

MRI findings in a dog with discospondylitis caused by Bordetella species

A case of discospondylitis in a dog secondary to Bordetella species, diagnosed early with the assistance of magnetic resonance imaging (MRI), is reported. The history and clinical signs were suggestive of possible discospondylitis. MRI identified changes and allowed a presumptive diagnosis of discospondylitis, which was subsequently confirmed by bacterial culture of biopsy material. Discospondylitis associated with Bordetella species infection has not, to the authors' knowledge, been previously reported in the dog.     

Extended antimicrobial susceptibility assay for Staphylococcus aureus isolates from bovine mastitis growing in biofilms

Staphylococcus aureus is one of the most prevalent causes of bovine mastitis. The antimicrobial treatment of this disease is currently based on antimicrobial susceptibility tests according to CLSI standards. However, various studies have shown that there is a discrepancy between the results of this standard susceptibility test and the actual cure rate of the applied antimicrobial treatment. Increasing evidence suggests that biofilm formation by S. aureus is associated with this problem. The currently available antimicrobial susceptibility assays for bacteria growing in biofilms, are not considered reliable enough for routine application. Therefore, the objective of this study was to further develop a susceptibility test for bacteria growing in biofilm, suitable for routine testing of the antimicrobial susceptibility of S. aureus. With the expansion of the available MBEC assay to an extended biofilm susceptibility test, that comprises 2 and 4 consecutive days of antimicrobial challenge, the antimicrobial susceptibility for S. aureus growing in biofilm was further analysed. The results showed clear differences between strains and various antimicrobial agents with respect to the effect of longer duration of the antimicrobial challenge on the eradication of S. aureus growing in biofilm. The extended biofilm susceptibility test also indicates that each bacterial strain requires a specific duration of antimicrobial therapy, which cannot be derived from a standard susceptibility test or from a 24-h biofilm susceptibility test.     

Methicillin-resistant staphylococci isolated from animals

Staphylococci isolated from animals (n=311) were screened for methicillin resistance by oxacillin agar screening. Oxacillin-resistant strains were tested for the presence of the mecA gene by PCR. Isolates were identified by standard techniques and 16S rDNA analysis, and their antimicrobial susceptibilities were tested using an agar diffusion method. MecA-positive strains were further analyzed using pulsed-field gel electrophoresis (PFGE). From 11 multidrug-resistant staphylococci, 6 were mecA-positive: 2 methicillin-resistant Staphylococcus aureus (MRSA) and 4 Staphylococcus haemolyticus. Screening of 300 staphylococci (100 S. aureus, 100 S. intermedius and 100 coagulase-negative staphylococci (CNS)) randomly chosen from the strain collection of the Veterinary Microbiological Diagnostic Center yielded five oxacillin-resistant coagulase-negative staphylococci, four of which were mecA-positive. PFGE showed that all mecA-positive staphylococci isolated from animals had distinct patterns. However, one MRSA isolated from a flank fistula of a dog showed homology to a human epidemic MRSA cluster, suggesting that transfer of MRSA between humans and dogs might occur.     

Osteomyelitis in the dog: microorganisms isolated and susceptibility to antimicrobial agents

In fifteen out of 17 (88%) radiographically diagnosed cases of osteomyelitis in the dog the lesion contained bacteria, the one most frequently isolated being Staphylococcus aureus. All bacteria isolated were tested to determine their susceptibility to various antimicrobial agents. The results of two methods of measuring susceptibilities, standard disk diffusion and minimal inhibitory concentration, are presented.     

RADIOGRAPHIC FINDINGS DURING RECOVERY FROM DISCOSPONDYLITIS

The diagnosis of discospondylitis is based on radiographic changes in the vertebrae. The limitations of this method are the time gap between the onset of clinical signs and the first appearance of the radiographic findings, as well as the disassociation between the clinical and radiographic signs during recovery. It is known that the radiographic changes appear only two to four weeks after the onset of clinical signs, but the characteristics of radiographic changes during recovery has yet to be documented, thus making follow-up radiographs difficult to interpret. A prospective and retrospective study was designed to document typical radiographic changes during recovery from discospondylitis. We reviewed 12 dogs that had complete and uneventful recovery with antibiotic therapy alone. Periodic follow-up radiographs and clinical examinations were conducted up to five months after the onset of clinical signs to correlate between the clinical status and radiographic changes during recovery. Although the clinical signs improved within the first 10 days of antibiotic therapy, the radiographic deterioration continued before regression and signs of radiographic recovery were noticed. This radiographic deterioration, despite successful antibiotic therapy, appeared shorter in young dogs (less than one year old) and lasted three to nine weeks in older dogs.     

Discospondylitis associated with three unreported bacteria in the dog

Three cases of discospondylitis in the dog, caused respectively by Pseudomonas aeruginosa, Enterococcus faecalis and Staphylococcus epidermidis, are reported. These bacteria have not previously been documented as being the cause of the condition in this species. The neurological involvement was severe in all three cases. Two dogs were paraplegic and one was tetraplegic, and one of the paraplegic dogs had no deep pain on the extremities of both pelvic limbs. All dogs were treated surgically with a satisfactory neurological recovery.     

Antibacterial activity of thionin Thi2.1 from Arabidopsis thaliana expressed by bovine endothelial cells against Staphylococcus aureus isolates from bovine mastitis

Bovine mastitis is mainly caused by Staphylococcus aureus and antimicrobial therapy, commonly used for its control, has resulted in an increase in the frequency of resistant staphylococci in recent years. Thus, alternative therapies are desirable and the antimicrobial peptides represent attractive control agents. In this work, we expressed the antimicrobial peptide thionin Thi2.1 cDNA from Arabidopsis thaliana in the bovine endothelial cell line BVE-E6E7 and evaluated its activity against bovine mastitis S. aureus isolates. A polyclonal population from BVE-E6E7 cells transfected with the pThi2.1 construct was obtained and thionin Thi2.1 expression was confirmed by RT-PCR. From this population, eight stably transfected cell clones were obtained and their conditioned media (CM) were evaluated against the S. aureus ATCC 27543 strain. Clones showed high antibacterial activity (>95%) relative to the activity of the polyclonal population. The C8 clone showed the highest antibacterial activity (>99%) and its CM was evaluated against eleven bovine mastitis S. aureus isolates. A 2.5microg aliquot of total protein from the C8 clone's CM inhibited the growth of S. aureus isolates (>40%) relative to the CM from BVE-E6E7 cells used as control. Growth inhibition of S. aureus isolates was dose-dependent, showing a total inhibition at concentrations higher than 3.12microg/ml. These results suggest that thionin Thi2.1 antimicrobial peptide could be use in the treatment of bovine mastitis.     

VERTEBRAL PHYSITIS: A RADIOGRAPHIC DIAGNOSIS TO BE SEPARATED FROM DISCOSPONDYLITIS

A retrospective study was initiated to investigate the incidence, radiographic appearance and progression of vertebral physitis, a condition the authors propose as a separate radiographic diagnosis from discospondylitis. From 30 dogs with an initial radiographic diagnosis of discospondylitis, six dogs (five less than two years old) had radiographic signs believed to represent vertebral physitis. Bone lysis initially confined to the caudal physeal zone of affected vertebrae and sparing the vertebral endplates characterized the vertebral physitis lesions. Subsequent collapse of the caudoventral vertebral body and reactive spondylosis arising only from the caudal vertebral margins followed as the lesions progressed. By contrast, discospondylitis lesions originated as symmetric lysis of the vertebral endplates with reactive sclerosis in both vertebral bodies, and subsequent symmetric spondylosis. As a result of the differing radiographic patterns demonstrated by the physitis and discospondylitis lesions the author's also propose an alternative pathogenesis from that which is generally accepted for discospondylitis.     

白头翁不同提取物抑菌作用研究

目的：探讨白头翁4种溶剂提取物抑菌作用。方法：采用K-B纸片扩散法测定不同提取物对金黄色葡萄球菌、大肠杆菌、沙门氏菌、枯草杆菌的抑菌效果。结果：白头翁的不同溶剂提取物均有一定的抑菌效果,且作用效果差异不明显,而其抑菌效果随着浓度的增加而增强,4种提取物对枯草杆菌抑菌效果均较差;高浓度时,除水提组分外,其他3种提取物对金黄色葡萄球菌均表现为中敏。     

东亚飞蝗抗菌活性物质的萃取及抗菌效应研究

试验研究东亚飞蝗成虫抗菌活性物质的萃取参数与抑菌效应。采用针刺蘸大肠杆菌菌悬液方法,以抗菌活性为指标,用杯碟法测定临床多重耐药菌的抑菌活性,确定最佳诱导时间,初步研究抗菌谱。结果表明,东亚飞蝗抗菌活性物质粗提液对革兰氏阳性菌(如金黄色葡萄球菌、枯草芽孢杆菌)或革兰氏阴性菌(如大肠杆菌、水稻白叶枯病原菌)均有一定的抑制作用。其抗菌谱为:金黄色葡萄球>水稻白叶枯病原菌>枯草芽孢杆菌>大肠杆菌,其中以对金黄色葡萄球菌的抑菌效果最明显。抗菌活性物质浓度为11.782mg/mL,蝗虫抗菌活性物质收率为8.623%。经纯化后的抗菌活性物质增强对革兰氏阳性菌或革兰氏阴性菌的抑制作用。采用针刺蘸大肠杆菌方式可成功诱导东亚飞蝗抗菌物质的表达,尤其以针刺蘸大肠杆菌诱导后饲养24h得到的抗菌活性物质抑菌活性最强。结果表明东亚飞蝗虫体内含有抗菌活性物质可被诱导表达,其抗菌作用机理有进一步研究。     

Mycobacterium goodii infection in a dog with concurrent hyperadrenocorticism

Abstract A 9-year-old Boston terrier was diagnosed with multifocal, nodular panniculitis caused by an organism belonging to the Mycobacterium smegmatis group by histological evaluation and bacteriological identification. The mycobacterial species was identified by direct gene sequence analysis and confirmed to be Mycobacterium goodii. Treatment using doxycycline and ciprofloxacin was successfully implemented for the mycobacterial panniculitis over a period of 9 months. Concurrent pituitary-dependent hyperadrenocorticism (Cushing's disease) was also identified using routine diagnostic methods and mitotane therapy was implemented. There was follow-up for 14 months after cessation of antimicrobial therapy with no recurrence of mycobacterial infection. Although cutaneous infections are frequently recognized as complications of canine pituitary-dependent hyperadrenocorticism, concurrent mycobacterial panniculitis due to any rapidly growing mycobacterium has not previously been reported. This is the first confirmed case of mycobacterial panniculitis due to M. goodii infection in a dog and also the first of any rapidly growing mycobacterial infection in a dog with concurrent endogenous Cushing's disease.     

宁夏地区奶牛乳房炎金黄色葡萄球菌耐药性分析

为了解宁夏地区奶牛乳房炎金黄色葡萄球菌的耐药情况,采用药敏纸片扩散法,测定了50株奶牛乳房炎金黄色葡萄球菌对常用的17种抗茵药物的耐药性.同时采用产色头孢菌素法进行β-内酰胺酶的检测,并采用苯唑西林纸片法进行耐甲氧西林金黄色葡萄球菌(MRSA)的检测.结果表明,所有菌株除了对利福平、万古霉素100％敏感以外,对其他15...