Case–control study of Staphylococcus lugdunensis infection isolates from small companion animals

Background – Coagulase‐negative Staphylococcus lugdunensis has recently been shown to cause invasive infections of people, which are similar in pathogenic effect to those caused by Staphylococcus aureus. Little is known about the pathogenicity of S. lugdunensis in companion animals. Objectives – To compare potential risk factors for infection, body sites affected, and whether cases and controls had been treated with antimicrobial drugs based upon susceptibility test results. Animals – Thirty‐three cases of S. lugdunensis infection (25 dogs, six cats and two small mammals) were identified between January 2003 and August 2011. Two Staphylococcus pseudintermedius controls, which were identified by the microbiology laboratory immediately before and after each S. lugdunensis case, were host‐species matched to each case. Methods – A retrospective case–control analysis. Results – During the period evaluated, the prevalence of S. lugdunensis infection was 1.3 cases per 10,000 hospital admissions for dogs and 0.95 cases per 10,000 admissions for cats (P = 0.453). In univariate analyses, S. pseudintermedius isolation was significantly associated with skin infections (P < 0.0001), while S. lugdunensis isolation was associated with the respiratory tract (P = 0.03) and other deep tissues (P = 0.005). Cases were less likely than controls to have been treated based upon susceptibility test results (P = 0.02). A conditional logistic regression analysis showed isolation of S. lugdunensis to be associated with recent (≤ 30 days) steroid administration (odds ratio, 17.72; 95% confidence interval, 2.35–132.82; P = 0.005); and in‐patient status (odds ratio, 9.67; 95% confidence interval, 2.18–42.88; P = 0.003). Conclusions – These results suggest that S. lugdunensis may cause invasive infections in companion animals, which should be treated with antimicrobials based upon susceptibility tests when available.     

Antimicrobial resistance in staphylococci from animals with particular reference to bovine Staphylococcus aureus, porcine Staphylococcus hyicus, and canine Staphylococcus intermedius.

Besides their role as commensals on the skin and mucosal surfaces, staphylococci may be involved in a wide variety of diseases in animals. Staphylococcal infections in animals are mainly treated with antimicrobial agents and as a consequence, staphylococci from animal sources have developed and/or acquired resistance to the respective antimicrobial agents. Resistance statistics obtained from national monitoring programmes on staphylococci from cattle and pigs, but also from surveillance studies on staphylococci involved in diseases in dogs are reported and reviewed with regard to their comparability. This review mainly focusses on the genetic basis of antimicrobial resistance in staphylococci of animal origin. Particular attention is paid to resistance to those antimicrobial agents which are most frequently used in veterinary medicine, but also to antimicrobial agents, such as chloramphenicol and mupirocin, which are used in specific cases for the control of staphylococcal infections in pets and companion animals. In addition, plasmids and transposons associated with the respective resistance properties and their ways of spreading between members of the same or different staphylococcal species, but also between staphylococci and other gram-positive bacteria, are described.     

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.     

Determination of staphylococcal exotoxins, SCCmec types, and genetic relatedness of Staphylococcus intermedius group isolates from veterinary staff, companion animals, and hospital environments in Korea

The Staphylococcus (S.) intermedius group (SIG) has been a main research subject in recent years. S. pseudintermedius causes pyoderma and otitis in companion animals as well as foodborne diseases. To prevent SIG-associated infection and disease outbreaks, identification of both staphylococcal exotoxins and staphylococcal cassette chromosome mec (SCCmec) types among SIG isolates may be helpful. In this study, it was found that a single isolate (one out of 178 SIG isolates examined) harbored the canine enterotoxin SEC gene. However, the S. intermedius exfoliative toxin gene was found in 166 SIG isolates although the S. aureus-derived exfoliative toxin genes, such as eta, etb and etd, were not detected. SCCmec typing resulted in classifying one isolate as SCCmec type IV, 41 isolates as type V (including three S. intermedius isolates), and 10 isolates as non-classifiable. Genetic relatedness of all S. pseudintermedius isolates recovered from veterinary staff, companion animals, and hospital environments was determined by pulsed-field gel electrophoresis. Strains having the same band patterns were detected in S. pseudintermedius isolates collected at 13 and 18 months, suggesting possible colonization and/or expansion of a specific S. pseudintermedius strain in a veterinary hospital.     

Antibiotic resistance and phylogenetic comparison of human,pet animals and raw milk Staphylococcus aureus isolates

The present study was conducted to compare the S. aureus isolates from different sources in the basis of resistance phenotypic and genotypic features and phylogenetic differences. Total of 70 S. aureus isolates (including 25 human, 25 raw milk and 20 pet animal isolates) were subjected to the antimicrobial susceptibility testing, polymerase chain reaction (PCR) detection of the resistance genes and DNA fingerprinting using random amplification of polymorphic DNA–PCR (RAPD-PCR) to survey the variability of the isolates. Among 70 S. aureus, 55 (78.5%) isolates were MRSA. The isolates showed the highest antibiotic resistance to methicillin, ampicillin and penicillin (78.5%) and showed the lowest resistance to ciprofloxacin (12.8%). ErmB and tetM resistance genes were present in all isolates and the vanA gene was not detected in any of the isolates. Thirteen distinct clusters were identified in RAPD-PCR fingerprinting. Statistical analysis showed that the isolates without resistance to antibiotics were significantly in associated with raw milk origin (P < 0.05). According to the results of the study, S. aureus strains with pets and raw milk origin are significant sources of antibiotic-resistant isolates such as MRSA. They are also carriers of resistance genes that can be transmit to human isolates and cause drug resistance in human infections. Identifying the source of these infections is possible with a reliable genotyping method such as RAPD-PCR.     

Prevalence and mechanism of antimicrobial resistance in Staphylococcus aureus isolates from diseased cattle, swine and chickens in Japan

Antimicrobial administration is essential for the control and treatment of diseases in animals, but the emergence and prevalence of antimicrobial-resistant Staphylococcus aureus is a significant concern during animal production. Here we investigated the antimicrobial susceptibility of S. aureus from diseased food-producing animals and molecularly characterized the methicillin-resistant and fluoroquinolone-resistant isolates. A total of 290 S. aureus isolates obtained from cattle (n=246), swine (n=16), and chickens (n=28) between 2003 and 2009 were examined for antimicrobial susceptibility against 9 antimicrobials using an agar dilution method. Resistance to penicillin (PC) was most frequently found (24.8%), followed by oxytetracycline (OTC, 10.0%), dihydrostreptomycin (4.1%), erythromycin (EM, 3.1%), enrofloxacin (ERFX, 2.1%), and kanamycin (1.7%). The PC resistance rate was significantly higher in swine than in cattle (P<0.01) and chickens (P<0.01). The resistance rates to OTC, EM and ERFX were significantly higher in swine and chickens than in cattle (P<0.05). Methicillin-resistant S. aureus (MRSA) was recovered from milk derived from a cow with mastitis in 2003; sequence type 8, SCCmec type IV and spa type t024. In the six ERFX-resistant strains isolated after 2003, amino acid substitutions in ParC with/without GyrA were detected. As the prevalence of MRSA and FQ-resistant S. aureus in the animals should be noticed, continuous monitoring is necessary to control resistance to clinically important antimicrobials in S. aureus from food-producing animals.     

Trends of antimicrobial resistance in bacterial isolates from a small animal referral hospital

A longitudinal, retrospective investigation was made of antimicrobial resistance in bacterial isolates obtained from clinical cases in a small animal hospital between 1989 and 1997. Isolates of Escherichia coli and Staphylococcus species were used as Gram-negative and Gram-positive indicator organisms, respectively, and the annual prevalence of antimicrobial resistance was calculated for each organism to each of nine (for E coli) and 11 (for Staphylococcus species) appropriate antimicrobials, including enrofloxacin. Using a chi-square test for trend, statistically significant, rising trends were identified in the resistance of E coli to amoxycillin (P=0.04), clavulanate-amoxycillin (P<0.01) and streptomycin (P<0.01), and in the resistance of Staphylococcus species to erythromycin (P<0.01). There was an equivocal, rising trend for the resistance of Staphylococcus species to cephalexin. No significant trends were apparent for any of the other 15 organism/drug interactions. The annual prevalence of multiple drug resistance was calculated for E coli, Proteus species, Pseudomonas species, staphylococci and streptococci, but no statistically significant trends were identified.     

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.     

Frequency of isolation and antimicrobial susceptibility patterns of Staphylococcus intermedius and Pseudomonas aeruginosa isolates from canine skin and ear samples over a 6-year period (1992-1997)

Staphylococcus intermedius (S. intermedius) was isolated from 88.6% and 49.4% of skin and ear samples, respectively, during the years 1992 through 1997, and frequency of isolation remained unchanged. More than 95% of all S. intermedius isolates were susceptible to cephalothin and oxacillin, providing support for empirical treatment of canine skin and ear infections with cephalexin. Pseudomonas aeruginosa (P. aeruginosa) was isolated from 7.5% and 27.8% of skin and ear samples, respectively. The frequency of isolation from skin samples increased over the study period. Because of multidrug-resistant profiles for P. aeruginosa isolates, especially for ear isolates, empirical treatment of P. aeruginosa infections is not advisable.     

Demographic data and treatment of small companion animals with lead poisoning: 347 cases (1977-1986)

Three hundred forty-seven cases of lead poisoning in small animals, diagnosed after 1976, were reviewed. The types of treatments used and their outcomes were analyzed. Changes in blood lead concentrations following various treatments, as well as the sources of lead exposure, were also reviewed. The geographic origins of the cases were traced, and demographic factors were studied to determine possible correlates that might explain the regional distribution of cases.     

An investigation of exudative epidermitis (greasy pig disease) and antimicrobial resistance patterns of Staphylococcus hyicus and Staphylococcus aureus isolated from clinical cases

Exudative epidermitis (EE) is a common skin disease of young pigs, caused mainly by Staphylococcus hyicus. Increased prevalence of EE and poor response to treatment are reported. Common strategies used by Ontario pork producers to treat pigs with EE were determined using a survey. Injection of penicillin G was reported as the most common parenteral antibiotic choice. Antimicrobial resistance patterns of S. hyicus and Staphylococcus aureus isolated from clinical cases (30 herds with samples from approximately 6 pigs per farm) showed that 97% of S. hyicus isolates were resistant to penicillin G and ampicillin; 71% of these isolates were resistant to ceftiofur. Similar resistance was noted among S. aureus isolates. Antimicrobial resistance has become a problem in the treatment of EE in Ontario.     

Clinical and laboratory findings in small companion animals with lead poisoning: 347 cases (1977-1986)

Three hundred forty-seven cases of lead poisoning in small companion animals were reviewed. The yearly prevalence and overall incidence rates were examined for the 10 years before and after enactment of strict federal regulations pertaining to lead content in paint products. Biographical data, clinical signs, and laboratory results were analyzed for the 6 types of affected animals (ie, dogs, cats, birds, rabbits, a chinchilla, and a raccoon). Clinical and laboratory findings of these animals were then compared with findings of other studies of lead intoxication.     

Antimicrobial resistance in Salmonella isolates from apparently healthy food-producing animal from 2000 to 2003: the first stage of Japanese veterinary antimicrobial resistance monitoring (JVARM)

Antimicrobial susceptibility of 183 Salmonella isolates from apparently healthy food-producing animals obtained during the period from 2000 to 2003 throughout Japan was examined. Of 29 serovars identified, Salmonella Infantis (37.7%) was the most prevalent, followed by S. Typhimurium (19.7%). Salmonella bacteria resistant to dihydrostreptomycin (77.6%) were about 10% more prevalent than those resistant to oxytetracycline (67.8%), though the nation-level veterinary use of tetracycline antibiotics is much greater than that of streptomycin in Japan. In seventeen isolates (9.3%) resistant to nalidixic acid, single point mutations were detected at 84 or 87 in the quinolone resistance-determining region of the gyrA gene.     

Genetic and enzymatic analyses of metalloprotease (aureolysin) from Staphylococcus aureus isolated from domestic animals.

The gene (aur) encoding the metalloprotease (aureolysin) of Staphylococcus aureus from domestic animals was analyzed by polymerase chain reaction (PCR), PCR-restriction fragment length polymorphism (PCR-RFLP) and sequencing. The aur gene was detected in all 74 isolates from cows, pigs and chickens by PCR amplification and was classified into types I and II by PCR-RFLP patterns. The type II aur gene was contained in 36 (94.7%) of 38 protease-positive isolates as judged by skim milk agar plate culture, while type I was contained in 28 (77.8%) of 36 protease-negative isolates. The deduced amino acid sequences of aureolysins from type I and II isolates were almost identical with those of the published data. Subsequently, the two aureolysins were purified from the culture supernatants of type I and II isolates. The molecular weights of purified type I and II aureolysins were both estimated at 34kDa by SDS-polyacrylamide gel electrophoresis. These aureolysins had maximum proteolytic activity at 30-50 degrees C and pH 7.0-8.0. Their activity was inhibited by metal- and zinc-specific inhibitors, such as EDTA, EGTA and 1,10-phenanthroline. Specific activity (activity/protein) of type II aureolysin was two times higher than that of type I. These results indicated that the aur gene is highly conserved with two allelic forms (types I and II) among bovine, porcine and avian isolates of S. aureus.     

Molecular types and antibiotic resistance of Staphylococcus aureus isolates from bovine mastitis in a single herd in China

The molecular diversity, antibiotic resistance patterns and presence of resistance genes were determined in Staphylococcus aureus isolates from cases of bovine mastitis in a dairy cattle herd in China. Multiple locus variable number tandem repeat analysis was used for molecular typing. Resistance was determined through minimum inhibitory concentrations and resistance genes were detected by PCR. There was low molecular diversity; one predominant strain (type I) accounted for the majority of cases of S. aureus mastitis in the herd and this strain had a high frequency of resistance to penicillin and tetracycline. The most prevalent resistance genes were blaZ, ermC and tetM.     

Prediction of penicillin resistance in Staphylococcus aureus isolates from dairy cows with mastitis, based on prior test results

AIM: To gauge how well prior laboratory test results predict in vitro penicillin resistance of Staphylococcus aureus isolates from dairy cows with mastitis. METHODS: Population-based data on the farm of origin (n=79), genotype based on pulsed-field gel electrophoresis (PFGE) results, and the penicillin-resistance status of Staph. aureus isolates (n=115) from milk samples collected from dairy cows with mastitis submitted to two diagnostic laboratories over a 6-month period were used. Data were mined stochastically using the all-possible-pairs method, binomial modelling and bootstrap simulation, to test whether prior test results enhance the accuracy of prediction of penicillin resistance on farms. RESULTS: Of all Staph. aureus isolates tested, 38% were penicillin resistant. A significant aggregation of penicillin-resistance status was evident within farms. The probability of random pairs of isolates from the same farm having the same penicillin-resistance status was 76%, compared with 53% for random pairings of samples across all farms. Thus, the resistance status of randomly selected isolates was 1.43 times more likely to correctly predict the status of other isolates from the same farm than the random population pairwise concordance probability (p=0.011). This effect was likely due to the clonal relationship of isolates within farms, as the predictive fraction attributable to prior test results was close to nil when the effect of within-farm clonal infections was withdrawn from the model. CONCLUSIONS: Knowledge of the penicillin-resistance status of a prior Staph. aureus isolate significantly enhanced the predictive capability of other isolates from the same farm. In the time and space frame of this study, clinicians using previous information from a farm would have more accurately predicted the penicillin-resistance status of an isolate than they would by chance alone on farms infected with clonal Staph. aureus isolates, but not on farms infected with highly genetically heterogeneous bacterial strains.     

Prediction of penicillin resistance in Staphylococcus aureus isolates from dairy cows with mastitis,based on prior test results

AIM: To gauge how well prior laboratory test results predict in vitro penicillin resistance of Staphylococcus aureus isolates from dairy cows with mastitis.

METHODS: Population-based data on the farm of origin (n=79), genotype based on pulsed-field gel electrophoresis (PFGE) results, and the penicillin-resistance status of Staph. aureus isolates (n=115) from milk samples collected from dairy cows with mastitis submitted to two diagnostic laboratories over a 6-month period were used. Data were mined stochastically using the all-possible-pairs method, binomial modelling and bootstrap simulation, to test whether prior test results enhance the accuracy of prediction of penicillin resistance on farms.

RESULTS: Of all Staph. aureus isolates tested, 38% were penicillin resistant. A significant aggregation of penicillin-resistance status was evident within farms. The probability of random pairs of isolates from the same farm having the same penicillin-resistance status was 76%, compared with 53% for random pairings of samples across all farms. Thus, the resistance status of randomly selected isolates was 1.43 times more likely to correctly predict the status of other isolates from the same farm than the random population pairwise concordance probability (p=0.011). This effect was likely due to the clonal relationship of isolates within farms, as the predictive fraction attributable to prior test results was close to nil when the effect of within-farm clonal infections was withdrawn from the model.

CONCLUSIONS: Knowledge of the penicillin-resistance status of a prior Staph. aureus isolate significantly enhanced the predictive capability of other isolates from the same farm. In the time and space frame of this study, clinicians using previous information from a farm would have more accurately predicted the penicillin-resistance status of an isolate than they would by chance alone on farms infected with clonal Staph. aureus isolates, but not on farms infected with highly genetically heterogeneous bacterial strains.     

Feline cutaneous hemangiosarcoma: a retrospective study of 18 cases (1998-2003)

Cutaneous hemangiosarcoma (HSA) has been infrequently reported in dogs and cats. Medical records of 18 cats diagnosed with cutaneous HSA were reviewed. Age at the time of diagnosis, breed, sex, tumor location, tumor size, treatment type, survival time, disease-free interval, and cause of death were evaluated. Aggressive surgical excision of the tumor was attempted in 10 cats. A complete surgical excision was achieved in five of the 10 cats. Median survival times were statistically longer in cats that underwent surgery versus cats that did not. Cats with cutaneous HSA treated with aggressive surgical excision of their tumors may have a good long-term prognosis.