Clindamycin-resistance in methicillin-resistant Staphylococcus aureus isolated from animals

Clindamycin is widely used in veterinary medicine to treat a variety of bacterial infections. Resistance to clindamycin amongst staphylococci may be due to modification of the ribosomal target site. Resistance due to this mechanism is encoded by the erm genes, which may be either constitutively or inducibly expressed. Inducible expression of resistance is not usually demonstrable by routine laboratory susceptibility testing, however, a relatively simple double disc agar diffusion test (D-test) may be used to detect the presence of inducible resistance. Two hundred and eighty-five isolates of methicillin-resistant Staphylococcus aureus (MRSA) isolated from infections in animals were tested using the D-test for the presence of inducible clindamycin resistance. One hundred and seven (71%) of the strains tested demonstrated inducible resistance to clindamycin, which were not detected on initial susceptibility testing. It has been shown that there is potential for staphylococci to develop resistance to clindamycin whilst on treatment when inducible resistance mechanisms are present. Therefore, routine screening for inducible resistance may be prudent.     

Methicillin-resistant Staphylococcus aureus (MRSA) isolated from animals and veterinary personnel in Ireland

Reports of methicillin-resistant Staphylococcus aureus (MRSA) in animals have become more frequent in recent years. This paper documents the recovery of MRSA from animals with respiratory, urinary tract or wound infection and from animals subjected to surgical procedures following treatment in one veterinary hospital and 16 private veterinary clinics in different geographical locations throughout Ireland. MRSA was recovered from 25 animals comprising 14 dogs, eight horses, one cat, one rabbit and a seal, and also from 10 attendant veterinary personnel. Clinical susceptibility testing suggested that the 35 isolates fell into two different groups. One group of isolates (Group 1) was resistant to one or more of the following classes of antimicrobials: macrolides, lincosamines, tetracyclines and/or fluoroquinolones. The second group (Group 2) was resistant to macrolides, aminoglycosides, tetracyclines and trimethoprim/sulphamethoxazole and variably resistant to fluoroquinolones, lincosamines and rifampicin. One isolate in Group 2 was susceptible to trimethoprim. Epidemiological typing by antibiogram-resistogram (AR) typing, biotyping and by chromosomal DNA restriction fragment length polymorphism analysis using SmaI digestion followed by pulsed field gel electrophoresis (PFGE), confirmed these two major clusters. PFGE analysis showed that most isolates from non-equine animals were indistinguishable from each other and from the isolates from personnel caring for these animals. MRSA was isolated from eight horses which attended six different veterinary practices before referral to an equine veterinary hospital. Isolates from the eight horses and from their attendant personnel had PFGE patterns that were indistinguishable and were unlike the patterns obtained from the other isolates. Comparison of PFGE patterns of isolates from veterinary sources with patterns from MRSA recovered in human hospitals showed that the most frequently occurring pattern of MRSA from non-equine animals was indistinguishable from the predominant pattern obtained from the most prevalent MRSA strain in the human population in Ireland. However, the patterns of the isolates from horses were unlike any patterns previously reported in Irish studies of human isolates. This study shows that transmission of two strains of MRSA is occurring in veterinary practices in Ireland and that one strain may have arisen from human hospitals. The source of the second strain remains to be determined.     

Antimicrobial susceptibility of Staphylococcus aureus and Staphylococcus pseudintermedius isolated from various animals

This study characterized the antimicrobial susceptibility of 221 Staphylococcus aureus isolated from various species, and 60 canine Staphylococcus pseudintermedius isolated from 1986 through 2000 at the Western College of Veterinary Medicine (WCVM). Resistance of S. aureus was most common to penicillin (31%) and tetracycline (14%); resistance of S. pseudintermedius to penicillin was present in 8% and to tetracycline in 34% of isolates. Resistance to trimethoprim/sulfamethoxazole was only seen among S. pseudintermedius, and there was no resistance to amoxicillin/clavulanate, ampicillin/sulbactam, cephalothin, amikacin, gentamicin, enrofloxacin, chloramphenicol, or rifampin among any isolate. Inducible clindamycin resistance was found in both S. aureus and S. pseudintermedius, highlighting the need for careful interpretation of culture and susceptibility test results. There were significant differences in the minimum inhibitory concentrations of penicillin, ciprofloxacin, enrofloxacin, clindamycin, erythromycin, chloramphenicol, and tetracycline between avian, bovine, equine, and porcine isolates.     

Leukotoxin family genes in Staphylococcus aureus isolated from domestic animals and prevalence of lukM-lukF-PV genes by bacteriophages in bovine isolates

Leukotoxin family genes in Staphylococcus aureus isolated from domestic animals were examined by polymerase chain reaction. LukS and lukF genes were detected in all 48 avian and 72 porcine isolates of S. aureus. LukE and lukD genes, located in a putative staphylococcal pathogenicity island (Sapln3/Saplm3), were recognized in 44 (91.7%) of 48 avian isolates, but these genes were not detected in porcine isolates. In 297 bovine isolates collected from mastitic cow's milk and bulk milk from dairy farms in two regions, lukM and lukF-PV(P83) genes in addition to lukS-lukF and lukE-lukD genes were detected in 100 (62.5%) of the 160 isolates from Ishikawa and in118 (86.1%) of the 137 isolates from Hokkaido. When the lysogeny of S. aureus bovine isolates was examined by treatment with mitomycin C, clearing of the culture due to cell lysis was observed in 34 (91.9%) of 37 lukM-lukF-PV(P83) genes--positive isolates. In addition, we isolated a novel lukM-lukF-PV(P83)-carrying (designated phiLukM), and revealed that the lukM-lukF-PV(P83) genes were located very close to an amidase gene on the temperate phage genomes. These results suggest horizontal transmission of lukM-lukF-PV(P83) genes by temperate bacteriophages in S. aureus of bovine origin.     

质粒介导的喹诺酮耐药基因在动物源金黄色葡萄球菌的流行分布

为了解广东省动物源金黄色葡萄球菌耐药现状、分析耐喹诺酮类金黄色葡萄球菌耐药分子特征,本研究从2010—2011年广东33个养殖场的不同动物来源的样本中分离鉴定出46株金黄色葡萄球菌,采用二倍琼脂稀释法测定对14种抗菌药物的敏感性;采用聚合酶链式反应(PCR)检测耐喹诺酮金黄色葡萄球菌grlA、grlB、gyrA、gyrB基因在喹诺酮耐药决定区(QRDR)的突变特征、质粒介导喹诺酮类耐药(PMQR)基因(qnr、aac6′-Ib-cr、oqxA和qepA)的流行分布特征,同时还检测了β-内酰胺酶编码基因(blaCTX-M、blaCMY和blaSHV)、质粒介导金黄色葡萄球菌耐氟苯尼考的基因(cfr和fexA)和万古霉素耐药基因(vanA、vanB和vanC)。结果表明,46株金黄色葡萄球菌对克林霉素耐药率最高为67%,对环丙沙星和氟苯尼考耐药率为52%,对青霉素、氨苄西林、庆大霉素、红霉素、四环素和复方新诺明的耐药率在40%⁵0%之间,对苯唑西林和氯霉素耐药率为28%,对妥布霉素耐药率为13%,对头孢噻肟的耐药率在10%左右,有2株耐万古霉素。20株耐环丙沙星金黄色葡萄球菌的grlA和gyrA基因的QRDR发生了碱基突变并导致编码的氨基酸发生改变,GrlA氨基酸只有1种突变模式,Ser80→Phe,而GyrA氨基酸存在3种突变模式:Ser84→Leu,Ala或Phe。PMQR基因中,oqxA检出率最高(80%),其次是aac6′-Ib-cr占13%,qnrS1检出3株、qnrD检出2株。检测到2株菌株携带超广谱β-内酰胺酶编码基因blaSHV-12;23株氟苯尼考耐药菌株全部携带fexA基因,其中3株同时携带cfr基因;2株耐万古霉素菌株未检测到相关耐药基因。广东省动物源金黄色葡萄球菌多重耐药现象较为普遍,本研究首次在动物源金黄色葡萄球菌中检测到超广谱质粒编码的喹诺酮耐药基因流行分布广泛,大多数菌株同时携带2种以上质粒编码的耐药基因,提示养殖过程或治疗过程中使用任何一种药物(尤其是动物促生长剂)都可以筛选出耐药菌株。     

Methicillin-resistant Staphylococcus aureus (MRSA) isolated from small and exotic animals at a university hospital during routine microbiological examinations

Clinical specimens of small animals (n=869) were screened for the occurrence of methicillin-sensitive and methicillin-resistant Staphylococcus aureus (MSSA; MRSA) during routine microbiological examinations, and results were confirmed by a multiplex PCR strategy. The genetic relatedness of all mecA-positive S. aureus isolates was further investigated by pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), PCR for Panton-Valentine leukocidine genes (PVL) and staphylococcal cassette chromosome mec-typing (SCCmec). A total of 61 S. aureus isolates were found during a 20-month period of investigation, 27 (44.3%) of them harbouring the mecA gene for methicillin-resistance. The majority of MRSA were isolated in specimens from dogs (n=18) and cats (n=4). One guinea pig and one rabbit were found to be positive for an MRSA infected site. Similarly, three exotic animals, a turtle, a bat and a parrot, were found to be infected with MRSA. PFGE and MLST analysis revealed a certain genotype ("A" and "A-1") dominating the isolate collection (23 of 27). Furthermore, one isolate showed homologous PFGE pattern to the German epidemic strain Barnim ("BE") and another one ("BE-1") was considered to be closely related. A third genotype ("B") was detected in two cases. Two different sequence types (ST) were identified among the 27 MRSA isolates. PFGE type "A" and both strains related to the Barnim epidemic strain were assigned to ST22, whereas ST239 was associated to PFGE profile "B". The present data show that certain MRSA genotypes are capable of infecting a wide spectrum of small and exotic animals, especially in clinical facilities.     

动物源金黄色葡萄球菌耐药性、oqxAB和fexA基因流行性及spa分型研究

为了解河南省不同动物源金黄色葡萄球菌的耐药情况、oqxAB和fexA基因的流行情况,分析spa基因多态性分型特点。用微量肉汤稀释法测定了分离菌对10种抗菌药物的敏感性,利用PCR方法检测金黄色葡萄球菌中的oqxAB和fexA耐药基因,扩增spa基因的X区域进行分型研究。结果表明,130株金黄色葡萄球菌分离株对大多数药物产生耐药,青霉素、红霉素、林可霉素、四环素、环丙沙星、恩诺沙星、氟苯尼考和喹乙醇对分离菌的耐药率分别为94.62%,95.38%,92.31%,70.77%,55.38%,57.69%,32.31%,19.23%,但对替加环素、万古霉素较敏感。PCR检测发现,35株携带fexA基因,检出率为26.92%。17株携带oqxAB基因,检出率为13.08%。此外,有10株同时携带oqxAB和fexA基因,耐药性检测发现这10株菌耐药性较为严重。130株分离菌中107株菌可通过spa分型,分为21种spa型,最常见的spa型是t15075 (15.38%),其次是t189 (13.85%),t034 (9.23%),t091 (7.69%),t127 (6.92%),t164 (6.15%)。此外,只有t034 (9.23%)和t3512 (3.85%)能够出现在3种不同动物源(分别是牛、猪、鸡及牛、猪、鸭)的菌株中。综上,oqxAB和fexA基因在河南省的动物养殖场中已有一定的流行,同时携带oqxAB和fexA基因的菌株耐药性较为严重,spa型别具有多样性和差异性的特点,故临床应加强耐药性及分型监测。     

Dermatophytes isolated from domestic and feral animals

In work over a period of 8 years, dermatophytes were recovered from 12 animal species in the North Island of New Zealand. A total of 552 dermatophytes were isolated and belonged to the Microsporum (6 species) and Trichophyton (6 species) genera.

Some unusual isolations are reported: Microsporum canis and Trichophyton mentagrophytes var. mentagrophytes were recovered from calves; Microsporum distortum from a dog, which was the first known isolation from an animal in the North Island; four horses, from the same stable, yielded Microsporum equinum which has not previously been recorded in this country; Trichophyton erinacei was recovered from lesions on a cat which is the first report of the dermatophyte from an animal other than the dog, hedgehog or man; Trichophyton equinum var. autotrophicum was a rare isolation from a dog.

Species affinity was demonstrated with the dermatophytes M. canis; M. nanum; M. equinum; T. equinum; and T. verrucosum. These zoophilic species appear to be passed between individuals of the same species, with occasional infection in man and other animal species. T. mentagrophytes var. mentagrophytes had a wider distribution, being isolated from dogs, cats, guinea-pigs and rats. The infection in rats was subclinical.

The geophilic species M. cookei, T. ajelloiand and T. terrestre were recorded but not regarded as being pathogenic. M. gypseum was significant in cases involving dogs, horses and a cat, as arthrospores were seen invading the affected hairs.     

Genetic diversity of Staphylococcus aureus isolated from ovine intramammary infections in Norway

Three hundred and eighty-four Staphylococcus aureus isolates obtained from mammary secretions from 332 ewes kept for meat production were typed by pulsed-field gel electrophoresis (PFGE). The ewes were from 242 flocks located in 13 counties distributed in four regions of Norway. In total, 64 different pulsotypes were identified, 31 of these were represented by a single isolate. Fifty-nine percent of the isolates belonged to one of five closely related pulsotypes. This group of pulsotypes occurred in all the counties. Although widely disseminated, the proportions of the prevalent and closely related pulsotypes differed between the regions. Nine pulsotypes were unique to single regions but the number of isolates belonging to each of these pulsotypes was low. Resistance to penicillin was found in only 3 of the 384 S. aureus isolates. These represented three different single banding patterns, not related to any of the prevalent pulsotypes found.     

Genotyping of Staphylococcus aureus isolated from bovine mastitis.

The present study was designed to comparatively investigate 25 Staphylococcus aureus strains isolated from bovine subclinical mastitis. The S. aureus strains, obtained from six different farms at five locations in one region of Germany, were characterized by phenotypic and genotypic methods. The S. aureus could be identified and further characterized by their cultural, biochemical and hemolytic properties. To analyze the epidemiological relationship the isolates were subjected to DNA fingerprinting by macrorestriction analysis of their chromosomal DNA, by PCR amplification of the gene encoding the 16S-23S rRNA intergenic spacer, by PCR amplification of the gene encoding the IgG binding region and the X region of protein A and by amplifying, and subsequent, digestion of the gene encoding staphylococcal coagulase. The macrorestriction analysis revealed five DNA restriction patterns with DNA patterns I, III and IV occurring in three, four, and three different farms, respectively. In addition, clones with different DNA patterns could be found within one herd. The PCR products for the spacer DNA, the spa gene encoding the X region of protein A and the coa gene encoding coagulase corresponded mostly to the pattern observed by DNA fingerprinting. Amplification of the gene encoding the IgG binding region revealed sizes of 620 bp for 20 of the isolates and 280 bp for four isolates indicating, for the latter, a deletion of segments in this region. These findings show, that single, widely distributed clones seemed to be responsible for cases of bovine subclinical mastitis found in one region of Germany.     

Staphylococcus aureus (MSSA) and MRSA (CC398) isolated from post-mortem samples from pigs

There are many reports on the occurrence of Livestock Associated Methicilline resistant Staphylococcus aureus (LA-MRSA, CC398) in healthy pigs. There are however, very few reports of LA-MRSA being associated with pathological lesions in pigs. With this study we try to find the answers to the questions: (1) how often is S. aureus found in post-mortem material from pigs, (2) how many of these isolates are methicillin resistant, (3) are these equally distributed over the years? Here we report the isolation of MRSA and of methicillin sensitive S. aureus (MSSA) from samples derived from post-mortem examinations at the Animal Health Service in The Netherlands in the period from 2003 through October 2008. The MSSA and MRSA described here were isolated from 159 pathological lesions and from 7 submissions of aborted foetuses derived from a total of 116 animals, representing 103 submissions coming from 92 different herds. This is approximately 0.5% of all pigs submitted for post mortem examination in those years. The proportion of pigs from which S. aureus (both MSSA and MRSA) was isolated from, did not increase over the years. MSSA (N=97) and LA-MRSA CC398 (N=18) were present mainly in (peri)arthritis in over 30% of all cases, but were also isolated from internal organs such as lung, brain, spleen, kidneys, heart, indicating septicaemia. Remarkably, one non-CC398 MRSA (ST1) was isolated in a joint and a kidney of one pig. This isolate was resistant to 5 out of 6 antimicrobials tested. There was no significant difference in the type of lesions in which LA-MRSA was found compared to MSSA. The number of antimicrobials these isolates were resistant to, increased rapidly after 2004. LA-MRSA was isolated for the first time in 2005 and then again in 2007 and 2008, suggesting that this is an emerging pathogen. However, due to changes in the panel of antimicrobials used to test S. aureus for antimicrobial susceptibility in 2005 and 2007, the possibility exists that we may have missed some MRSA isolates. LA-MRSA isolates are resistant to at least three but sometimes five out of six antimicrobials tested. All isolates were susceptible to the combination of Trimethoprim/Sulfamethaxol.     

Identification and characterization of methicillin-resistant Staphylococcus aureus (MRSA) from Austrian companion animals and horses

The aim of this study was to investigate the antimicrobial resistance, resistance gene patterns and genetic relatedness of a collection of Austrian methicillin-resistant Staphylococcus aureus (MRSA) isolates from companion animals and horses.A total of 89 non-repetitive MRSA isolates collected during routine veterinary microbiological examinations from April 2004 to the end of 2012, and one isolate from 2013 were used for this study. The presence of mecA and other resistance genes was confirmed by PCR. Isolates were genotyped by spa typing, two multiple-locus variable-number tandem repeat analyses (MLVA) analyses, SCCmec typing and multilocus sequence typing (MLST). PCR targeting Panton-Valentine leukocidin (PVL) and detection of staphylococcal enterotoxins (SE), toxic shock syndrome toxin (TSST) was performed using PCR assays. Antimicrobial susceptibility testing was performed.Five sequence types (STs—ST398, ST254, ST22, ST5 and ST1), SCCmec types II, IVa, V, and non-type-abele, 8 spa-types (t003, t011, t036, t127, t386, t1348, and t4450), and two isolates could not be assigned, 21 MLVA-14Orsay types Multiplex-PCR MLVA (mMLVA) displayed 17 different MLVA types.The present study is the most comprehensive dealing with MRSA from Austrian companion animals and horses. The results confirm that MRSA ST398 is present in a wide range of animal species and is predominant especially in horses. In other companion animals it is unclear whether the infections with the different MRSA isolates investigated in the present study truly represents a rare phenomenon or may be an emerging problem in companion animals.