中草药对耐甲氧西林葡萄球菌抑菌作用的研究

耐甲氧西林葡萄球菌（Methicillin-resistant Staphylococcus，MRS）是医院和社区获得性感染的重要病原。MRS除对万古霉素敏感外，几乎对现存的所有抗生素耐药。耐甲氧西林葡萄球菌感染已成为困扰临床的难题之一。     

动物源性耐甲氧西林葡萄球菌mecA的PCR检测及耐药性分析

耐甲氧西林葡萄球菌(methicillin-resistant Staphylococcus,MRS)包括耐甲氧西林金黄色葡萄球菌(methicillin-resistant Staphylococcus aureus,MRSA)和耐甲氧西林凝固酶阴性葡萄球菌(methicillin-resistant coagulase-negative Staphylococci,MRCNS).     

动物医院环境源性葡萄球菌耐药性分析与毒力基因检测

为了解动物医院环境源性葡萄球菌耐药情况及毒力基因携带率,一年内连续多次对北京3家大型动物医院进行空气和物表采样,分离得到137株葡萄球菌。通过纸片扩散法药敏试验调查葡萄球菌的耐药情况,并结合毒力基因检测对耐甲氧西林葡萄球菌(MRS)进行鉴定。结果阿奇霉素、复方新诺明的耐药率最高,分别为54.01%和48.91%;其次为克林霉素及氨苄西林,耐药率分别为37.96%和34.31%;庆大霉素及阿米卡星的耐药率非常低,敏感率达到100%和99.27%。共检测出32株耐甲氧西林葡萄球菌(MRS),其中25株存在mec A耐药基因。另外,在所有葡萄球菌中,pvl毒力基因的携带率为27.01%,ica D基因携带率为27.74%。表明动物医院环境源性葡萄球菌耐药性严重,毒力基因携带率较高,应予以重视。     

耐甲氧西林金黄色葡萄球菌分离鉴定及耐药基因检测

为了解动物源性金黄色葡萄球菌对市售常见的各种兽用抗生素药物的耐药情况,掌握并分析其耐药性,指导临床合理使用抗菌药物。本研究通过常规细菌分离鉴定患病动物炎性分泌物,对分离菌株进行生化试验、耐药性试验、耐甲氧西林金黄色葡萄球菌(Methicillin-resistant S.aureus,MRSA)鉴定和耐药基因鉴定,获得4株耐药金黄色葡萄球菌,2株为MRSA,2株为甲氧西林敏感的金黄色葡萄球菌(Methicillinsusceptible S.aureus,MSSA);4株金黄色葡萄球菌均检测出tetA、aac(6')/aph(2')、sul1耐药基因,其中2株MRSA检测出mecA。MRSA与MSSA均表现出了多重耐药现象,其中MRSA比MSSA的耐药现象更为广泛。因此,要更加关注MRSA的流行情况,制定规范的用药行为,严控抗生素药物的滥用。     

中国部分地区犬源伪中间葡萄球菌的流行特征分析

旨在调查犬源伪中间葡萄球菌的耐药性和分子特征，本研究自2017年11月—2019年4月收集601份送检至中国农业大学动物医院检验科和第三方检测机构的犬源临床样本，分离鉴定伪中间葡萄球菌；采用琼脂稀释法检测伪中间葡萄球菌对14种抗菌药物的敏感性；所有分离菌株均进行全基因组测序（WGS），并从WGS结果中获取耐药基因、多位点序列分型（ST）和葡萄球菌染色体基因盒（SCCmec）分型。结果显示，共分离到75株伪中间葡萄球菌（分离率为12.5%），其中包括42株（56%）耐甲氧西林伪中间葡萄球菌（MRSP）和33株（44%）甲氧西林敏感伪中间葡萄球菌（MSSP）；所有菌株均对青霉素、阿奇霉素、克林霉素、多西环素、环丙沙星、恩诺沙星、苯唑西林和氯霉素高度耐药，对利奈唑胺、万古霉素、阿米卡星和利福平敏感，多重耐药率达90.7%；所有MRSP均具有多重耐药性；75株伪中间葡萄球菌中检测到19种耐药基因，blaZ和aac（6'）-aph（2″）检出率最高，均为92%（69/75）；共发现70种ST型，54种为新ST型，无优势ST型；23株（54.7%） MRSP为SCCmec V型。综上表明，犬源伪中间葡萄球菌存在严重的多重耐药性；MRSP和MSSP均具有较大的遗传多样性。     

EFSA对影响猪群感染MRSA的因素进行评估

欧盟EFSA（欧洲食品安全局）公布了一份评估报告，对在欧盟猪场中影响MRSA（耐甲氧西林金黄色葡萄球菌Staphylococcus aureus）传播的因素进行了评估。     

牛源耐甲氧西林金黄色葡萄球菌的分离鉴定

从奶牛分离得到耐甲氧西林金黄色葡萄球菌（methieillin—resistant Staphylococcus aureus,MRSA）。按常规方法复苏菌株,用血浆凝固酶试验鉴定SA。用KB法、琼脂筛选法、生化鉴定法（VITEK32）、聚合酶链反应等鉴定MRSA。常规分离鏊定的葡萄球菌468株,其中凝固酶阴性葡萄球菌（coagulase negative Staphylococcus,CNS）361株,检出率为77．149,6,金黄色葡萄球菌（Staphylococcus aureus,SA）105株,检出率为22．44％,MRSA36株检出率为34．29％,2株未定型,占0．42％。而MRSA在乳房炎奶样中检出率高达34．29％,表明新疆兵团部分垦区牛场MRSA已经呈蔓延趋势。     

英国新药有望杀灭超级细菌

耐甲氧西林金黄色葡萄球菌被人们称为所谓的“超级病菌”。目前，科学家们正在研发一种治疗耐甲氧西林金黄色葡萄球菌传染病的药物，可能在3年内用于临床。方法很简单，将一种凝胶涂入鼻孔内便可杀死这种超级病菌。     

山羊金黄色葡萄球菌健康带菌情况的调查及耐药性分析

金黄色葡萄球菌是引起人和动物感染及食物中毒的重要病原体之一。为了解四川省山羊金黄色葡萄球菌的健康带菌情况及其耐药性,采集了省内4个养殖场共32只山羊的鼻腔棉拭子样本,进行金黄色葡萄球菌的分离、鉴定及药敏试验。共从11只羊的鼻腔棉拭子样本中分离出金黄色葡萄球菌,检出率为34.4％。对临床分离株进行了苯唑西林、头孢西丁、万古霉素等11种抗菌药物的药敏试验,结果表明,分离株对氨苄西林的耐药率为72.7％,对其它抗菌药物没有耐药性,未发现耐甲氧西林金黄色葡萄球菌（MRSA）。本研究结果表明,四川地区山羊的金黄色葡萄球菌的带菌情况较普遍,因此,应该规范屠宰过程的卫生操作,并进行严格监控,减少金黄色葡萄球菌的污染。     

国际动态

<正>耐药金黄葡萄球菌波及丹麦大部分养猪场2014年12月24日据悉,丹麦食品和农业部长承认"之前的工作不到位",新的研究表明,目前耐甲氧西林金黄色葡萄球菌的流行程度比之前预计的严重。丹麦的养猪场耐抗生素的耐甲氧西林金黄色葡萄球菌的流行程度在4年之内就翻了一番。一项分析结果显示,丹麦三分之二的生猪生产基地受到了耐甲氧西林金黄色葡萄球菌的影响。对丹麦超市中猪肉产品的抽检结果显示,每5包猪肉中有1包中携带耐甲氧西林金黄色葡萄球菌。     

In vitro susceptibility testing of meticillin-resistant and meticillin-susceptible staphylococci to mupirocin and novobiocin

Antimicrobials effective against meticillin-resistant staphylococci are limited. Mupirocin is a topical antimicrobial used to treat bacterial skin infections. Novobiocin is an oral antimicrobial approved for treatment of staphylococcal upper respiratory infections in dogs. This study reports the in vitro activity of mupirocin and novobiocin on meticillin-susceptible (MSS) and resistant staphylococci (MRS) from healthy dogs and dogs with superficial pyoderma. Staphylococci were isolated from skin swabs at four sites on healthy dogs and from lesions on dogs with superficial pyoderma. Staphylococci were identified by morphology and by catalase and coagulase testing. Speciation and susceptibility testing were performed by the Dade Microscan (W. Sacramento, CA, USA). Meticillin resistance was confirmed by an oxacillin screen plate. Novobiocin and mupirocin susceptibilities were tested by disc diffusion. Staphylococci were cultured from 61 healthy dogs (17 MRS and 44 MSS) and 30 dogs with pyoderma (15 MRS and 15 MSS), with higher proportions of MRS isolates in dogs with pyoderma (P=0.038; χ(2) test). For mupirocin, 79.5% (35 of 44) MSS and 82.3% (14 of 17) MRS isolates from healthy dogs, and 100% (15 of 15) MSS and 86.6% (13 of 15) MRS isolates from dogs with pyoderma were susceptible (MSS, P=0.094; MRS, P=1.0; Fisher's exact test). For novobiocin, 95.4% (42 of 44) MSS and 52.9% (nine of 17) MRS isolates from healthy dogs and 93.3% (14 of 15) MSS and 80% (12 of 15) MRS isolates from dogs with pyoderma were susceptible (MSS, P=1.0; MRS, P=0.148; Fisher's exact test).     

Prevalence of and risk factors for isolation of meticillin‐resistant Staphylococcus spp. from dogs with pyoderma in northern California,USA

Background – Canine pyodermas associated with meticillin‐resistant Staphylococcus spp. (MRS) have increased in prevalence over the past decade. Hypothesis/Objectives – To compare the prevalence of MRS isolation from dogs with superficial pyoderma at a primary care clinic (PCC) and those at a tertiary care facility (VMTH) in California, USA, and identify associated risk factors. Animals – Client‐owned dogs from the VMTH (80 dogs) and the PCC (30 dogs). Methods – Aerobic bacterial culture and antibiotic susceptibility were performed on swab specimens collected from dogs, and meticillin resistance was determined using microdilution methods according to Clinical and Laboratory Standards Institute guidelines. A mecA gene PCR assay was used to confirm meticillin resistance when possible. Results – Of 89 staphylococcal isolates from the VMTH, 34 (38.2%) were meticillin resistant. In 31 dogs, pyoderma persisted, and one or more follow‐up isolates were obtained. The species isolated and drug susceptibility changed unpredictably during treatment. Of 33 PCC isolates, nine (27.3%) were meticillin resistant. Multiple drug resistance was identified in 41 of 53 (77.3%) MRS isolates from the VMTH and five of nine from the PCC. The sensitivity and specificity of PCR for the detection of meticillin resistance was 34 of 39 (87%) and 86 of 87 (99%), respectively. Risk factors for meticillin resistance for both sites were antibiotic treatment within the last year (P = 0.001), and for VMTH, hospitalization of dogs within the last year (P = 0.001). Conclusions and clinical importance – The prevalence of meticillin resistance was not different between VMTH and PCC isolates (P = 0.29). Previous antimicrobial therapy was an important risk factor for the isolation of MRS at both sites.     

Prevalence,species distribution and antimicrobial resistance patterns of methicillin-resistant staphylococci in Lithuanian pet animals

Background

The bacterial genus Staphylococcus consists of many species that causes infections in pet animals. Antimicrobial resistant staphylococci cause infections that are difficult to treat and they are important from the point of one health perspective. The aim of this study was to determine the prevalence of methicillin-resistant Staphylococcus (MRS) species, including methicillin-resistant S. aureus (MRSA) in diseased pet animals (Group A) and kennel dogs (Group B) in Lithuania and to characterize the isolates according to their antimicrobial resistance.

Results

Twenty-one MRS isolates were obtained from 395 clinical samples (5.3 %; CI 95 % 3.5-8.0) of Group A animals. Sixteen, four and one isolates were from dogs, cats and a pet rabbit, respectively. The mecA gene was present in 20 isolates, whereas one isolate was positive for the mecC gene. Twenty-one MRS isolates (20.0 %; CI 95 % 13.5-28.6) were obtained from the vagina of female dogs (n = 105) (Group B). All isolates carried the mecA gene. Twelve MRS species were isolated of which S. pseudintermedius was the most common (18/42) followed by S. haemolyticus (8/42) and S. lentus (4/42). MRSA was not found. All MRS strains were susceptible to vancomycin, linezolid, daptomycin and quinupristin/dalfopristin. Resistance to tetracycline (16/21), clindamycin (15/21) and erythromycin (14/21) was the most common types of resistance in Group A animals. Three isolates also demonstrated resistance to rifampin. Resistance toward gentamicin (16/21), ciprofloxacin (15/21), macrolides (15/21) and tetracycline (12/21) was the most common in kennel dogs (Group B). The most common genes encoding resistance to antimicrobials (excluding beta-lactams) in isolates from Group A pets were tetK (21/42), aph(3′)-IIIa (11/42) and aac(6'')-Ie-aph(2'''')-Ia (9/42).

Conclusions

A wide range of MRS species were found in pet animals in Lithuania. MRSA was not found.     

Risk factors associated with the antimicrobial resistance of staphylococci in canine pyoderma

This study reports the susceptibility to antimicrobial agents of staphylococci (n=105) isolated from dogs, and the factors associated with this resistance. The study animals were 23 healthy dogs (group A), 24 with first-time pyoderma (group B), and 27 with recurrent pyoderma that had undergone long-term antibiotic treatment (group C). Staphylococci were more commonly isolated from the pyoderma-affected than the healthy dogs (p<0.0001). Some 78% of the isolates were resistant to at least one antimicrobial agent. Resistance to amoxicillin-clavulanate, cephalosporins (OR 4.29, 95% CI [1.15, 16.3] respectively), enrofloxacin (OR 9.47, 95% CI [1.53, 58.5]) and ciprofloxacin (OR 79.7 95% CI [3.26, 1947.4]) was more common among group C isolates. Some 32% of all the isolates were multiresistant (MR) and 10.4% were methicillin-resistant (MRS). The probability of isolating MRS staphylococci in group C increased by a factor of four (95% CI [1.18, 17.9]) compared to A plus B. Multi-resistant (MR) isolates were obtained more commonly from urban than rural dogs (OR 3.79, 95% CI [1.09, 13.17]). All the MRS staphylococci encountered were obtained from urban dogs and more commonly from male dogs (p=0.07). This study shows that dogs bred in urban habitat, with a history of antibiotic therapy in the past year represents significant risk of being carriers of isolates resistant to methicillin (MRS) and other antimicrobials. These factors should be considered before applying an antimicrobial treatment in veterinary clinics.     

Non-clinical intramammary infection in lactating ewes and its association with clinical mastitis

A bacteriological survey for the study of non-clinical intramammary infection in the sheep udder was carried out in 88 Assaf ewes. A mean infection prevalence in the first few weeks of lactation was 55%. The most common bacterial isolates were Micrococcus spp. followed by coagulase negative staphylococcus, together accounting for 93% of the total number of isolates. An infection prevalence of 54% was found in ewelambs 2 days after their first lambing, indicating a marked new infection rate around lambing. Generally, the course of lactation was characterized by dynamic changes of new infection and spontaneous resolution. About 5% of half udders examined developed clinical mastitis. The comparison of bacteriological data from mastitic milk samples and from samples taken from the same half udders before the appearance of the clinical disease could not support the theory that in sheep, mastitis is a clinical exacerbation of a non-clinical intramammary infection.     

Screening for methicillin-resistant staphylococci in dogs admitted to a veterinary teaching hospital

This study investigated the nasal carriage of methicillin-resistant staphylococci (MRS) in dogs (n=177) prior to medical examination or surgery in a veterinary teaching hospital. Nasal swab samples were collected after induction of anaesthesia and incubated overnight in salt enriched trypticase-soy broth. Cultures were analysed on two different agar media containing cefoxitin. Suspected MRS isolates were genotypically identified and characterised by antimicrobial susceptibility testing and staphylococcal cassette chromosome mec (SCCmec)-typing. Methicillin-resistant Staphylococcus aureus (MRSA) isolates were additionally characterised by spa-typing and multilocus sequence typing. The presence of Panton-Valentine leukocidin (pvl) genes was determined by PCR. MRS carriage was compared between animals with or without an infectious process. Two MRSA were isolated, both belonging to typical Belgian human hospital clones and lacking pvl. Additionally a methicillin-resistant Staphylococcus haemolyticus carrying a type V SCCmec was detected. No relationship was observed between MRS carriage and presence of infections. The results suggest that MRS are present in dogs originating from the community, albeit at a low prevalence. This could pose risks for cross contamination of dogs and their owners.     

分泌抗金黄色葡萄球菌细菌素乳酸菌的分离鉴定

为分离和筛选产抗金黄色葡萄球菌乳酸菌素的优势乳酸菌,利用乳酸菌分离培养基MRS从收集的各种腌制菜汁中分离培养乳酸菌,通过细菌培养特性、革兰氏染色特点、生理生化特性初步鉴定,同时根据Genbank中乳酸菌的16SrDNA序列设计特异性引物,采用PCR方法进一步鉴定,并以金黄色葡萄球菌为指示菌对乳酸菌的发酵上清液进行抑菌特性研究。结果表明,从腌渍菜汁中分离获得90株产酸菌,通过形态学、生理生化特性和PCR鉴定,结果73株产酸菌为乳酸杆菌;分泌产物抑菌试验表明,有10株菌具有抑制金黄色葡萄球菌活性,经酸排除和过氧化氢排除试验,仍然有5株乳酸菌的分泌产物具有抑制金黄色葡萄球菌活性。可见,从腌渍菜汁分离到的乳酸菌具有抑制金黄色葡萄球菌活性的特性,主要是通过分泌乳酸菌素来发挥作用。     

The prevalence of methicillin-resistant staphylococci in healthy horses in the Netherlands

Two hundred healthy horses housed at 23 different farms and one clinic and 42 persons in close contact with these horses were screened for the presence of methicillin resistant staphylococci. Samples were taken from the nose and the pastern of the horses and from the nose and throat of the humans and incubated in selective media. Isolates were identified by standard techniques and their susceptibilities were tested using an agar diffusion method. Methicillin-resistant strains were tested for the presence of the mecA gene by PCR. In 45 horses (22.5%) and 15 humans (35.7%) mecA positive staphylococci were found. All isolates were coagulase negative staphylococci, except for one methicillin-resistant Staphylococcus aureus isolated from a veterinarian. Staphylococcus sciuri was the predominant species found among the methicillin resistant staphylococci (MRS) in the horses, whereas S. epidermidis predominated in the humans. From the horses, often more than one species of MRS could be isolated, resulting in a total of 175 mecA positive equine isolates. The equine isolates were predominantly susceptible to most antimicrobials tested, whereas the human isolates showed more resistance. In conclusion, no methicillin-resistant Staphylococcus aureus was found in healthy horses in the Netherlands, but methicillin-resistant coagulase negative staphylococci were found frequently. Further studies are needed in order to investigate whether horses can be a reservoir for MRS or the mecA gene for humans.     

Occurrence and characterization of methicillin-resistant staphylococci from bovine mastitis milk samples in Finland

Background

Methicillin-resistant staphylococci (MRS) are increasingly being isolated in bovine mastitis. The aim of our study was to evaluate the occurrence of MRS in Finnish mastitis milk samples and characterize the MRS isolates using molecular methods.

Results

Methicillin-resistant S. aureus (MRSA) was a rare finding in bovine mastitis in Finland. Only two out of 135 (1.5%) S. aureus isolates were positive for mec genes. One of these carried mecA and was of spa type t172, SCCmec type IV and ST375, and the other harboured mecC, being spa type t3256, and ST130. MRSA ST375 is common among human MRSA isolates in Finland, but this is the first report in the country of bovine mecC MRSA. In coagulase-negative staphylococci (CoNS) originating from bovine mastitis, methicillin resistance was more common. In the two CoNS collections studied, 5.2% (17/324) and 1.8% (2/110) of the isolates were mecA positive. Eighteen of these were methicillin-resistant S. epidermidis (MRSE), which were divided into 6 separate PFGE clusters. One pulsotype was detected in different parts of the country, indicating clonal spread. Most MRSE (13/18) were of SCCmec type IV, one was of type V and four were non-typeable. Comparison with a human staphylococcal database indicated that bovine MRSE strains were not closely related to human MRSE isolates.

Conclusions

The occurrence of MRS, especially MRSA, in bovine mastitis in Finland was low. Most methicillin-resistant bovine CoNS are MRSE, and we found evidence of a bovine MRSE strain that may spread clonally. This is the first report of a Finnish bovine isolate of MRSA_mecC ST130. The study provides a baseline for further MRS monitoring.     

一株优良乳酸菌的分离鉴定与特性研究

利用乳酸菌分离专用培养基-MRS培养基从发酵40 d的酸菜汁中分离得到一株乳酸菌,利用经典分类法对所分离的乳酸菌菌株进行了系统的细菌学鉴定和生物学特性研究。结果该菌株被鉴定为乳杆菌属、植物乳杆菌。对其进行生长曲线、pH及酸度的测定,结果显示分离乳酸菌的对数生长期较长;培养以后pH下降达到稳定;酸度较高的产酸时间为前20 h。抑菌试验表明：该菌株对大肠杆菌、金黄色葡萄球菌均有明显抑制作用。由于该菌具有生长快、产酸量高并具有抑菌活性等特点,因而适合作为微生态制剂的优良菌种开发利用。