Z A . 2000. Samples were obtained from 65 unmedicated adult dogs, processed for isolation of Staphylococcus species and tested for susceptibility to penicillin G, gentamicin, oxacillin, tetracycline, trimethoprimsulphamethoxazole, streptomycin, ampicillin and rifampin. Forty-four isolates were obtained, which represents 67Á7% of samples. Coagulase-negative species were most commonly found, and the most frequently isolated staphylococcus species were Staph. epidermidis and Staph. aureus. Other species, such as Staph. simulans, Staph. haemolyticus, Staph. saprophyticus and Staph. intermedius were also isolated. Resistance to antibiotics was frequently observed, with 90Á9% of the isolates showing resistance to at least one drug. The most active antimicrobial agents against staphylococci isolated from otitis externa of dogs were rifampin and oxacillin. Multidrug resistance was a common ®nding, and one strain of Staph. haemolyticus species, was resistant to all tested antimicrobial agents. Resistance to three or more different drugs was a common ®nding, observed in 16 strains (36Á4%) of both coagulase-positive and coagulase-negative staphylococci. This study highlights the emergence of cases of otitis externa determined by coagulase-negative staphylococcus strains and once more emphasizes the need for bacterial culture with species identi®cation and susceptibility testing of swab specimens from the ear canal in order to choose appropriate antimicrobial agents.

W . L IL E NB AU M , A .L . ES TE V ES AN D G. N S O UZ A. 1999. Samples were collected from 150 adult cats, processed for isolation of Staphylococcus species and tested for susceptibility to penicillin G, gentamicin, oxacillin, enrofloxin and tetracycline. Methicillin resistance was also determined. One hundred and four isolates were obtained (69·3% of samples). Coagulase-negative species were most common, and the most frequently isolated (33 samples) species was Staph. felis. Other coagulase-negative species, such as Staph. haemolyticus, Staph. simulans, Staph. epidermidis and Staph. saprophyticus were also isolated. Coagulase-positive staphylococci were obtained from 30 cats, and the only species recovered in this group was Staph. intermedius. Resistance to antibiotics was frequently observed, with 68·2% of the isolates showing resistance to at least one drug. Resistance to Penicillin G was observed in 68 of the 104 isolates (65·4%), 23 samples were resistant to oxacillin (22·1%), 33 to tetracycline (31·7%) and 24 to enrofloxin (23·1%). Gentamicin was the most active antimicrobial agent. The role of these microorganisms in the saliva of cats is discussed.

A study was designed to recover Listeria monocytogenes from pasteurized milk and Minas frescal cheese (MFC) sampled at retail establishments (REs) and to identify the contamination source(s) of these products in the corresponding dairy processing plant. Fifty milk samples (9 brands) and 55 MFC samples (10 brands) were tested from REs located in Juiz de Fora, Minas Gerais, Brazil. All milk samples and 45 samples from 9 of 10 MFC brands tested negative for L. monocytogenes; however, "brand F" of MFC obtained from REs 119 and 159 tested positive. Thus, the farm/plant that produced brand F MFC was sampled; all samples from the milking parlor tested negative for L. monocytogenes, whereas several sites within the processing plant and the MFC samples tested positive. All 344 isolates recovered from retail MFC, plant F MFC, and plant F environmental samples were serotype 1/2a and displayed the same AscI or ApaI fingerprints. Since these results established that the storage coolers served as the contamination source of the MFC, plant F was closed so that corrective renovations could be made. Following renovation, samples from sites that previously tested positive for the pathogen were collected from the processing environment and from MFC on multiple visits; all tested negative for L. monocytogenes. In addition, on subsequent visits to REs 159 and 119, all MFC samples tested negative for the pathogen. Studies are ongoing to quantify the prevalence, levels, and types of L. monocytogenes in MFC and associated processing plants to lessen the likelihood of listeriosis in Brazil.

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