In Vitro Persistence Level Reflects In Vivo Antibiotic Survival of Natural Pseudomonas aeruginosa Isolates in a Murine Lung Infection Model.

Clinicians are increasingly confronted with the limitations of antibiotics to clear bacterial infections in patients. It has long been assumed that only antibiotic resistance plays a pivotal role in this phenomenon. Indeed, the worldwide emergence of antibiotic resistance is considered one of the major health threats of the 21st century. However, the presence of persister cells also has a significant influence on treatment outcomes. These antibiotic-tolerant cells are present in every bacterial population and are the result of the phenotypic switching of normal, antibiotic-sensitive cells. Persister cells complicate current antibiotic therapies and contribute to the development of resistance. In the past, extensive research has been performed to investigate persistence in laboratory settings; however, antibiotic tolerance under conditions that mimic the clinical setting remain poorly understood. In this study, we optimized a mouse model for lung infections with the opportunistic pathogen Pseudomonas aeruginosa. In this model, mice are intratracheally infected with P. aeruginosa embedded in seaweed alginate beads and subsequently treated with tobramycin via nasal droplets. A diverse panel of 18 P. aeruginosa strains originating from environmental, human, and animal clinical sources was selected to assess survival in the animal model. Survival levels were positively correlated with the survival levels determined via time-kill assays, a common method to study persistence in the laboratory. We showed that survival levels are comparable and thus that the classical persister assays are indicative of antibiotic tolerance in a clinical setting. The optimized animal model also enables us to test potential antipersister therapies and study persistence in relevant settings. IMPORTANCE The importance of targeting persister cells in antibiotic therapies is becoming more evident, as these antibiotic-tolerant cells underlie relapsing infections and resistance development. Here, we studied persistence in a clinically relevant pathogen, Pseudomonas aeruginosa. It is one of the six ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, P. aeruginosa, and Enterobacter spp.), which are considered major health threats. P. aeruginosa is mostly known to cause chronic lung infections in cystic fibrosis patients. We mimicked these lung infections in a mouse model to study persistence under more clinical conditions. It was shown that the survival levels of natural P. aeruginosa isolates in this model are positively correlated with the survival levels measured in classical persistence assays in vitro. These results not only validate the use of our current techniques to study persistence but also open opportunities to study new persistence mechanisms or evaluate new antipersister strategies in vivo.

Selected strategies to fight pathogenic bacteria.

Natural products and analogues are a source of antibacterial drug discovery. Considering drug resistance levels emerging for antibiotics, identification of bacterial metalloenzymes and the synthesis of selective inhibitors are interesting for antibacterial agent development. Peptide nucleic acids are attractive antisense and antigene agents representing a novel strategy to target pathogens due to their unique mechanism of action. Antisense inhibition and development of antisense peptide nucleic acids is a new approach to antibacterial agents. Due to the increased resistance of biofilms to antibiotics, alternative therapeutic options are necessary. To develop antimicrobial strategies, optimised in vitro and in vivo models are needed. In vivo models to study biofilm-related respiratory infections, device-related infections: ventilator-associated pneumonia, tissue-related infections: chronic infection models based on alginate or agar beads, methods to battle biofilm-related infections are discussed. Drug delivery in case of antibacterials often is a serious issue therefore this review includes overview of drug delivery nanosystems.

R othia mucilaginosa is an anti-inflammatory bacterium in the respiratory tract of patients with chronic lung disease.

BACKGROUND: Chronic airway inflammation is the main driver of pathogenesis in respiratory diseases such as severe asthma, chronic obstructive pulmonary disease, cystic fibrosis (CF) and bronchiectasis. While the role of common pathogens in airway inflammation is widely recognised, the influence of other microbiota members is still poorly understood. METHODS: We hypothesised that the lung microbiota contains bacteria with immunomodulatory activity which modulate net levels of immune activation by key respiratory pathogens. Therefore, we assessed the immunomodulatory effect of several members of the lung microbiota frequently reported as present in CF lower respiratory tract samples. RESULTS: We show that Rothia mucilaginosa, a common resident of the oral cavity that is also often detectable in the lower airways in chronic disease, has an inhibitory effect on pathogen- or lipopolysaccharide-induced pro-inflammatory responses, in vitro (three-dimensional cell culture model) and in vivo (mouse model). Furthermore, in a cohort of adults with bronchiectasis, the abundance of Rothia species was negatively correlated with pro-inflammatory markers (interleukin (IL)-8 and IL-1ß) and matrix metalloproteinase (MMP)-1, MMP-8 and MMP-9 in sputum. Mechanistic studies revealed that R. mucilaginosa inhibits NF-κB pathway activation by reducing the phosphorylation of IκBα and consequently the expression of NF-κB target genes. CONCLUSIONS: These findings indicate that the presence of R. mucilaginosa in the lower airways potentially mitigates inflammation, which could in turn influence the severity and progression of chronic respiratory disorders.

Improvement of the enrichment used in the EMJH medium (Ellinghausen-McCullough-Johnson-Harris) for the cultivation of Leptospira spp.

Changes were made to the original formulation of the EMJH medium (Ellinghausen-McCullough-Johnson-Harris) enrichment and some aspects such as growth time of Leptospira and utilization in the microscopic agglutination test (MAT) were evaluated and compared to the original enrichment and to a commercially available enrichment (DIFCO™). Leptospira samples (24 antigens) that make up our panel of antigens used in MAT were used, among them, reference and autochthonous strains isolated in Brazil. The samples were grown individually in the EMJH medium under the three previously mentioned conditions (adapted enrichment, original enrichment and commercial enrichment). In addition, 89 blood serums from domestic and wild animals were analyzed by MAT using the antigens grown in these media. All samples tested grew efficiently with the adapted enrichment, and the MAT results were satisfactory. Therefore, other laboratories could also benefit from the use of this adapted enrichment when culturing the Leptospira strains applied in their MAT panels.

Interlaboratory study for the evaluation of three microtiter plate-based biofilm quantification methods.

Microtiter plate methods are commonly used for biofilm assessment. However, results obtained with these methods have often been difficult to reproduce. Hence, it is important to obtain a better understanding of the repeatability and reproducibility of these methods. An interlaboratory study was performed in five different laboratories to evaluate the reproducibility and responsiveness of three methods to quantify Staphylococcus aureus biofilm formation in 96-well microtiter plates: crystal violet, resazurin, and plate counts. An inter-lab protocol was developed for the study. The protocol was separated into three steps: biofilm growth, biofilm challenge, biofilm assessment. For control experiments participants performed the growth and assessment steps only. For treatment experiments, all three steps were performed and the efficacy of sodium hypochlorite (NaOCl) in killing S. aureus biofilms was evaluated. In control experiments, on the log10-scale, the reproducibility SD (SR) was 0.44 for crystal violet, 0.53 for resazurin, and 0.92 for the plate counts. In the treatment experiments, plate counts had the best responsiveness to different levels of efficacy and also the best reproducibility with respect to responsiveness (Slope/SR = 1.02), making it the more reliable method to use in an antimicrobial efficacy test. This study showed that the microtiter plate is a versatile and easy-to-use biofilm reactor, which exhibits good repeatability and reproducibility for different types of assessment methods, as long as a suitable experimental design and statistical analysis is applied.

Coupling Additive Manufacturing with Hot Melt Extrusion Technologies to Validate a Ventilator-Associated Pneumonia Mouse Model.

Additive manufacturing is widely used to produce highly complex structures. Moreover, this technology has proven its superiority in producing tools which can be used in different applications. We designed and produced an extrusion nozzle that allowed us to hot melt extrude drug-loaded tubes. The tubes were an essential part of a new mouse ventilator-associated pneumonia (VAP) model. Ciprofloxacin (CPX) was selected for its expected activity against the pathogen Staphylococcus aureus and ease of incorporation into thermoplastic polyurethane (TPU). TPU was selected as the carrier polymer for its biocompatibility and use in a variety of medical devices such as tubing and catheters. The effect of loading CPX within the TPU polymeric matrix and the physicochemical properties of the produced tubes were investigated. CPX showed good thermal stability and in vitro activity in preventing S. aureus biofilm formation after loading within the tube's polymeric matrix. Moreover, the produced tubes showed anti-infective efficacy in vivo. The produced tubes, which were extruded via our novel nozzle, were vital for the validation of our mouse VAP model. This model can be adopted to investigate other antibacterial and antibiofilm compounds incorporated in polymeric tubes using hot melt extrusion.

Molecular Typing and Antimicrobial Susceptibility Profile of Staphylococcus aureus Isolates Recovered from Bovine Mastitis and Nasal Samples.

In the present study, we aimed to determine the antimicrobial resistance and molecular typing of Staphylococcus aureus recovered from transient and persistent intramammary infections and nares/muzzles in dairy cows. We investigated the antimicrobial resistance of 189 S. aureus strains using a broad antimicrobial susceptibility profile. Furthermore, 107 S. aureus isolates were strain-typed using staphylococcal protein-A (spa) typing. A large proportion of strains exhibited multidrug resistance to antimicrobials, including resistance to critically important antimicrobials, although no methicillin-resistant S. aureus strains were found. Our study did not strengthen the idea that extramammary niches (i.e., nares/muzzles) are an important source of S. aureus for bovine mastitis. A discrepancy in the antimicrobial resistance between S. aureus strains isolated from nares/muzzles and milk samples was observed. Furthermore, S. aureus isolates from transient and persistent intramammary infections (IMIs) did not differ by spa typing, suggesting that the persistence of bovine IMIs was determined by cow factors. Thus, the high level of multidrug-resistant S. aureus found in the two herds, considered together with the predominance of a well udder-adapted S. aureus strain, may contribute to our knowledge of the history of the high prevalence of mastitis caused by S. aureus, which is of great concern for animal and public health.

Leptospira transport medium (LTM): A practical tool for leptospires isolation.

The isolation of Leptospira is challenging, since the bacteria of this genus are susceptible to adverse environmental conditions and may not remain viable for extend periods in urine samples. This study attempted to develop and evaluate a simple and practical method to isolate leptospires from bovine urine samples. A culture medium for sample transport, named Leptospira Transport Medium (LTM), was described and validated using reference serovars of Leptospira spp. in addition to autochthonous strains isolated in Brazil. We evaluated LTM in the field, by collecting 215 urine samples from slaughtered cattle and immediately seeding them in LTM and Fletcher's medium, used as control. The cultures were sent to a laboratory within 10 days for further processing. Moreover, 16S PCR was also performed on the urine samples directly to detect Leptospira DNA. Using LTM enabled 52 isolates (24.2%) to be obtained in pure culture, and contamination was only observed in 15/215 samples (7.0%). Regarding the samples in Fletcher's medium, 10 (4.6%) isolates were obtained. With 16S PCR performed in the urine samples, 31 samples (14.4%) were determined to be positive. LTM was developed and used in a simple and practical way and can significantly improve the isolation of leptospires from urine samples, as well as being highly useful in remote areas, not only in Brazil but also in other countries where few easily accessible laboratories are available. Furthermore, LTM can be prepared by laboratories and provided to veterinarians and technicians for urine collection in the field.

Optimization and Characterization of a Galleria mellonella Larval Infection Model for Virulence Studies and the Evaluation of Therapeutics Against Streptococcus pneumoniae.

Streptococcus pneumoniae is the leading cause of bacterial pneumonia. Infection is linked to high morbidity and mortality rates and antibiotic resistance within this pathogen is on the rise. Therefore, there is a need for novel antimicrobial therapies. To lower the time and costs of the drug discovery process, alternative in vivo models should be considered. As such, Galleria mellonella larvae can be of great value. The larval immunity consisting of several types of haemocytes is remarkably similar to the human innate immune system. Furthermore, these larvae don't require specific housing, are cheap and are easy to handle. In this study, the use of a G. mellonella infection model to study early pneumococcal infections and treatment is proposed. Firstly, the fitness of this model to study pneumococcal virulence factors is confirmed using streptococcal strains TIGR4, ATCC®49619, D39 and its capsule-deficient counterpart R6 at different inoculum sizes. The streptococcal polysaccharide capsule is considered the most important virulence factor without which streptococci are unable to sustain an in vivo infection. Kaplan-Meier survival curves showed indeed a higher larval survival after infection with streptococcal strain R6 compared to strain D39. Then, the infection was characterized by determining the number of haemocytes, production of oxygen free radicals and bacterial burden at several time points during the course of infection. Lastly, treatment of infected larvae with the standard antibiotics amoxicillin and moxifloxacin was evaluated. Treatment has proven to have a positive outcome on the course of infection, depending on the administered dosage. These data imply that G. mellonella larvae can be used to evaluate antimicrobial therapies against S. pneumoniae, apart from using the larval model to study streptococcal properties. The in-depth knowledge acquired regarding this model, makes it more suitable for use in future research.

Isolation and genetic characterization of Toxoplasma gondii from free-ranging and captive birds and mammals in Pernambuco state, Brazil / Isolamento e caracterização genética de Toxoplasma gondii de aves e mamíferos de vida livre e cativeiro em Pernambuco

Abstract Recent genetic population studies on Toxoplasma gondii in Brazil have shown large genetic variability. The objective of the present study was to isolate and genotypically characterize T. gondii from free-ranging and captive wild mammals and birds in Pernambuco state, Brazil. Fragments of heart, brain, skeletal muscle and diaphragm tissue from 71 birds and 34 mammals, which were either free-ranging or captive, were collected. Samples from 32 of these animals were subjected to bioassays in mice. Samples from the remaining 73 animals underwent biomolecular diagnosis, using PCR technique, targeting a repetitive DNA fragment of 529 bp in T. gondii. A non-virulent isolate (TgButstBrPE1) was obtained from a free-ranging striated heron (Butorides striata) and, based on primary samples, seven animals were found to be positive. The primary samples and the isolate obtained were subjected to PCR-RFLP using the markers SAG1, 5'3'SAG2, alt.SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, Apico and CS3. ToxoDB-RFLP genotype #13 from the striated heron isolate and Type BrIII genotype from a captive otter ( Lontra longicaudis) (PS-TgLonloBrPE1) were obtained. The present study describes the first isolation and genotypic characterization of T. gondii in free-ranging striated heron, and the first genotypic characterization of T. gondii in a captive otter.

Resumo Recentes estudos genéticos nas populações deste parasita no Brasil têm mostrado grande variabilidade genética. O objetivo do presente estudo foi isolar e caracterizar genotipicamente T. gondii de aves e mamíferos de vida livre e de cativeiro no estado de Pernambuco, Brazil. Fragmentos de tecido do coração, cérebro, músculo esquelético e diafragma de 71 aves e 34 mamíferos de vida livre ou cativeiro foram colhidos. Amostras de 32 destes animais foram submetidas a bioensaios em camundongos. As amostras dos 73 animais restantes foram submetidas a diagnóstico biomolecular usando a técnica de PCR, tendo como alvo o fragmento repetitivo de 529 pb do DNA de T. gondii. Dentre os 32 bioensaios conduzidos, obteve-se um isolado não-virulento (TgButstBrPE1) de um socozinho (Butorides striata ) de vida livre, e dentre as amostras primárias, sete animais foram positivos. As amostras primárias e o isolado foram submetidos a PCR-RFLP usando os marcadores SAG1, 5'3'SAG2, alt.SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, Apico e CS3. Foram obtidos o genótipo ToxoDB-RFLP #13 do isolado do socozinho e o genótipo Type BrIII de uma lontra (Lontra longicaudis) de cativeiro (PS-TgLonloBrPE1). O presente estudo descreve o primeiro isolamento e caracterização genotípica de T. gondii em socozinho de vida livre, e a primeira caracterização genotípica de T. gondii em lontra em cativeiro.

Isolation and genetic characterization of Toxoplasma gondii from free-ranging and captive birds and mammals in Pernambuco state, Brazil.

Recent genetic population studies on Toxoplasma gondii in Brazil have shown large genetic variability. The objective of the present study was to isolate and genotypically characterize T. gondii from free-ranging and captive wild mammals and birds in Pernambuco state, Brazil. Fragments of heart, brain, skeletal muscle and diaphragm tissue from 71 birds and 34 mammals, which were either free-ranging or captive, were collected. Samples from 32 of these animals were subjected to bioassays in mice. Samples from the remaining 73 animals underwent biomolecular diagnosis, using PCR technique, targeting a repetitive DNA fragment of 529 bp in T. gondii. A non-virulent isolate (TgButstBrPE1) was obtained from a free-ranging striated heron (Butorides striata) and, based on primary samples, seven animals were found to be positive. The primary samples and the isolate obtained were subjected to PCR-RFLP using the markers SAG1, 5'3'SAG2, alt.SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, Apico and CS3. ToxoDB-RFLP genotype #13 from the striated heron isolate and Type BrIII genotype from a captive otter ( Lontra longicaudis) (PS-TgLonloBrPE1) were obtained. The present study describes the first isolation and genotypic characterization of T. gondii in free-ranging striated heron, and the first genotypic characterization of T. gondii in a captive otter.

Experimental Neospora caninum infection in chickens (Gallus gallus domesticus) with oocysts and tachyzoites of two recent isolates reveals resistance to infection.

The importance of birds in the biological cycle of Neospora caninum is not clear. We report unsuccessful Neospora infection in chickens (Gallus gallus domesticus) using two isolates of N. caninum. In experiment #1, 30 White Leghorn chickens were orally inoculated with viable N. caninum oocysts (NC-SP1 isolate, 200 oocysts per bird) via the crop at 21days of age. Groups of three birds were euthanised at intervals of 7days (a total of 9weeks) and one group was challenged with the same oocyst dose at 37daysp.i. and observed for 11weeks. Blood samples were collected weekly, and sera were tested using IFAT. Chicken tissues were collected for PCR, quantitative PCR and immunohistochemistry. Two dogs approximately 45days of age were fed with tissues from chickens euthanised at 138 and 159daysp.i. The results indicated that the chickens were resistant to neosporosis as revealed by failure to seroconvert, to detect parasite DNA or N. caninum antigen by immunohistochemistry in inoculated bird tissues, and by no oocyst excretion by the dogs fed avian tissues. Similar results were obtained in experiment #2, in which 34 1-week-old chickens were each s.c. inoculated with 100,000 tachyzoites of the NcWTDMn1 isolate of N. caninum. The chickens were euthanised on days 7, 15, 22, 28, 36 and 60p.i. At necropsy, all tissues and serum from each bird were collected. All chickens remained asymptomatic, and N. caninum antigen was not detected by immunohistochemistry. Seven chickens euthanised at day 60p.i. demonstrated low (1:25 dilution) levels of antibodies by using the Neospora agglutination test. Two 12-week-old dogs fed tissues pooled from 10 inoculated chickens euthanised at day 60p.i. did not excrete N. caninum oocysts. This investigation indicates that chickens are resistant to experimental infection by N. caninum.

Cat-rodent Toxoplasma gondii Type II-variant circulation and limited genetic diversity on the Island of Fernando de Noronha, Brazil.

BACKGROUND: In Brazil, studies on animals and humans in mainland areas have shown that most strains of Toxoplasma gondii are pathogenic to mice and exhibit great genetic variability. RESULTS: In this study, using a set of 11 PCR-RFLP and 15 microsatellite markers, we isolated and genetically characterised T. gondii strains from one cat and three rats on Fernando de Noronha Island. The cat had antibodies to T. gondii, which were revealed using a modified agglutination test (MAT, cut-off 1:25) and the seroprevalence among the 46 rodents was 15.2%. Viable T. gondii was isolated from one cat (TgCatBrFN1), two brown rats (TgRatnoBrFN1 and TgRatnoBrFN2) and one black rat (TgRatraBrFN1). Unlike the strains from mainland Brazil, these isolates were not pathogenic to outbred mice. The genotypes of these strains were compared with strains previously isolated on the island and in mainland Brazil. The analysis based on microsatellite data showed a limited genetic diversity of T. gondii on Fernando de Noronha Island with the majority of strains clustered into the following three groups: type II, III, and Caribbean 1. CONCLUSIONS: There was little variation among strains within the same group, suggesting that the majority of strains circulating on Fernando de Noronha are derived from only a few strains that were recently introduced to the island, likely from imported cats. Except for the strain belonging to the Caribbean 1 group that originates from northeast Brazil, there was little evidence that strains from the other groups were introduced to Fernando de Noronha via mainland Brazil.

Isolation and biological and molecular characterization of Neospora caninum (NC-SP1) from a naturally infected adult asymptomatic cattle (Bos taurus) in the state of São Paulo, Brazil.

The biological and genetic diversity of Neospora caninum is very limited because of availability of only a few viable isolates worldwide. This study describes the isolation and biological and molecular characterization of a new viable isolate of N. caninum (NC-SP1), from a cattle in Brazil. Approximately 400 g of brain from a naturally infected adult male cattle from an abattoir was fed to a 2-month-old dog. Neospora-like oocysts were observed on day 7 post-inoculation (PI) and the duration of oocyst shedding was 14 days. The DNA obtained from oocysts was characterized molecularly and the final sequence was 99% identical to homologous sequences of N. caninum available in GenBank®. For bioassay, gerbils (Meriones unguiculatus) were orally inoculated with 10 100 and 1000 oocysts; all gerbils remained clinically normal but developed N. caninum antibodies 14 days PI. Cell culture isolation was successful using the brain homogenate from one of the gerbils and tachyzoites were observed 24 days PI. Microsatellite genotyping revealed a unique genetic profile for this new reference isolate.

Isolation and genetic characterization of Toxoplasma gondii from free-ranging and captive birds and mammals in Pernambuco state, Brazil

Abstract Recent genetic population studies on Toxoplasma gondii in Brazil have shown large genetic variability. The objective of the present study was to isolate and genotypically characterize T. gondii from free-ranging and captive wild mammals and birds in Pernambuco state, Brazil. Fragments of heart, brain, skeletal muscle and diaphragm tissue from 71 birds and 34 mammals, which were either free-ranging or captive, were collected. Samples from 32 of these animals were subjected to bioassays in mice. Samples from the remaining 73 animals underwent biomolecular diagnosis, using PCR technique, targeting a repetitive DNA fragment of 529 bp in T. gondii. A non-virulent isolate (TgButstBrPE1) was obtained from a free-ranging striated heron (Butorides striata) and, based on primary samples, seven animals were found to be positive. The primary samples and the isolate obtained were subjected to PCR-RFLP using the markers SAG1, 53SAG2, alt.SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, Apico and CS3. ToxoDB-RFLP genotype /13 from the striated heron isolate and Type BrIII genotype from a captive otter ( Lontra longicaudis) (PS-TgLonloBrPE1) were obtained. The present study describes the first isolation and genotypic characterization of T. gondii in free-ranging striated heron, and the first genotypic characterization of T. gondii in a captive otter.

Resumo Recentes estudos genéticos nas populações deste parasita no Brasil têm mostrado grande variabilidade genética. O objetivo do presente estudo foi isolar e caracterizar genotipicamente T. gondii de aves e mamíferos de vida livre e de cativeiro no estado de Pernambuco, Brazil. Fragmentos de tecido do coração, cérebro, músculo esquelético e diafragma de 71 aves e 34 mamíferos de vida livre ou cativeiro foram colhidos. Amostras de 32 destes animais foram submetidas a bioensaios em camundongos. As amostras dos 73 animais restantes foram submetidas a diagnóstico biomolecular usando a técnica de PCR, tendo como alvo o fragmento repetitivo de 529 pb do DNA de T. gondii. Dentre os 32 bioensaios conduzidos, obteve-se um isolado não-virulento (TgButstBrPE1) de um socozinho (Butorides striata ) de vida livre, e dentre as amostras primárias, sete animais foram positivos. As amostras primárias e o isolado foram submetidos a PCR-RFLP usando os marcadores SAG1, 53SAG2, alt.SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, Apico e CS3. Foram obtidos o genótipo ToxoDB-RFLP /13 do isolado do socozinho e o genótipo Type BrIII de uma lontra (Lontra longicaudis) de cativeiro (PS-TgLonloBrPE1). O presente estudo descreve o primeiro isolamento e caracterização genotípica de T. gondii em socozinho de vida livre, e a primeira caracterização genotípica de T. gondii em lontra em cativeiro.

Multidrug-resistant Staphylococcus pseudintermedius isolated from dog: case report / Staphylococcus pseudintermedius multirresistente isolado do cão: relato de caso

The zoonotic potential of multidrug resistant (MDR) bacteria is a worldwide concern and companion animals have been implicated in the spread of resistant bacteria. Therefore, surveillance is important, as there are reports of transmission of these bacteria from dog to men, as well as from men to dog. A 5-year-old mixed-breed male dog was admitted with obstructive struvite urolithiasis relapsing for over 18 months, in Botucatu, in the state of São Paulo, Brazil. The strain, biochemically identified as Staphylococcus spp., was MDR and was treated off-label with vancomycin, which resulted in clinical cure. The strain was molecularly identified as Staphylococcus pseudintermedius and the mecA gene was identified. This is the main gene responsible for methicillin-resistant S. pseudintermedius (MRSP), which is often resistant to multiple antimicrobials. The hypotheses for this clinical case are the transmission from man to animal, since the tutor was an intensivist doctor, or the bacterium itself could be part of the animal's microbiota and due to other factors, such as stress or obstructive urinary disease, opened a doorway to infection by S. pseudintermedius. Further studies should elucidate the transmission of MDR bacteria between human and pets.(AU)

O potencial zoonótico de bactérias multirresistentes é uma preocupação global e os animais de companhia têm sido implicados na disseminação de bactérias resistentes; assim, é importante a vigilância, pois já existem relatos de transmissão destas bactérias do cão para o homem e vice-versa. Um cão, sem raça definida e de cinco anos de idade, foi atendido na cidade de Botucatu, São Paulo, Brasil, apresentando urolitíase obstrutiva de estruvita recorrente há um ano e meio. Na urocultura do animal foi isolada uma estirpe de Staphylococcus spp. multirresistente; o tratamento com vancomicina possibilitou acura clínica. A estirpe de Staphylococcus spp. isolada foi identificada molecularmente como S. pseudintermedius e nela foi identificada a presença do gene mecA, o principal responsável por S. pseuidintermedius resistente à meticilina (MRSP), e que é frequentemente resistente à múltiplos antimicrobianos. As hipóteses para este caso clínico são a transmissão do homem para o animal, pois o tutor era um médico intensivista, ou que a própria bactéria fazia parte da microbiota do animal e, devido a outros fatores como estresse e doença urinária obstrutiva, abriu-se uma porta de entrada para a infecção pelo S. pseudintermedius. Mais estudos são necessários para a elucidação da transmissão de bactérias multirresistentes entre animais de companhia e o ser humano.(AU)