Faye A. Hartmann

Bacterial Culture Results from Liver, Gallbladder, or Bile in 248 Dogs and Cats Evaluated for Hepatobiliary Disease: 1998–2003

BACKGROUND Information is lacking on the prevalence and susceptibility patterns of bacterial isolates in dogs and cats with suspected hepatobiliary disease. OBJECTIVES To characterize the prevalence, identity, and antimicrobial susceptibility of common hepatobiliary isolates from such patients. ANIMALS Dogs and cats presented to the University of Wisconsin-Madison Veterinary Medical Teaching Hospital for which samples of bile, gallbladder, or liver were submitted for culture from 1998 to 2003, including 190 dogs (192 culture episodes) and 58 cats (61 culture episodes). METHODS Cases were identified from the microbiology laboratory database. Data from patient medical records were extracted, including the history of antimicrobial administration, the presence of fever, the results of CBC and serum biochemistry, the presence of biliary obstruction or hepatobiliary inflammation, and the results of aerobic and anaerobic bacterial cultures and aerobic antimicrobial susceptibilities. RESULTS Biliary cultures yielded a significantly higher percentage of positive results overall (30% [18 of 60]) than did hepatic cultures (7% [15 of 215]). In patients with cholecystitis, 62% (8 of 13) had positive biliary cultures. In patients with hepatic inflammation, 23% (7 of 30) had positive bile cultures, whereas only 6% (6 of 103) had positive hepatic cultures. Escherichia coli, Enterococcus spp., Bacteroides spp., Streptococcus spp., and Clostridium spp. were the most common true-positive isolates. More than 80% of Enterobacteriaceae were susceptible to ciprofloxacin or aminoglycosides, with only 30-67% susceptible to first-generation aminopenicillins and cephalosporins. Liver samples obtained by surgery or laparoscopy were more likely to yield positive cultures than those obtained by percutaneous needle biopsy.

Methicillin-resistant staphylococci: implications for our food supply?

Abstract Food-borne intoxication, caused by heat-stable enterotoxins produced by Staphylococcus aureus, causes over 240,000 cases of food-borne illness in the United States annually. Other staphylococci commonly associated with animals may also produce these enterotoxins. Foods may be contaminated by infected food handlers during slaughter and processing of livestock or by cross-contamination during food preparation. S. aureus also causes a variety of mild to severe skin and soft tissue infections in humans and other animals. Antibiotic resistance is common in staphylococci. Hospital-associated (HA) S. aureus are resistant to numerous antibiotics, with methicillin-resistant S. aureus (MRSA) presenting significant challenges in health care facilities for over 40 years. During the mid-1990s new human MRSA strains developed outside of hospitals and were termed community-associated (CA). A few years later, MRSA was isolated from horses and methicillin resistance was detected in Staphylococcus intermedius/pseudintermedius from dogs and cats. In 2003, a livestock-associated (LA) MRSA strain was first detected in swine. These methicillin-resistant staphylococci pose additional food safety and occupational health concerns. MRSA has been detected in a small percentage of retail meat and raw milk samples indicating a potential risk for food-borne transmission of MRSA. Persons working with animals or handling meat products may be at increased risk for antibiotic-resistant infections. This review discusses the scope of the problem of methicillin-resistant staphylococci and some strategies for control of these bacteria and prevention of illness.

The role of mecA and blaZ regulatory elements in mecA expression by regional clones of methicillin-resistant Staphylococcus pseudintermedius

Two major regional clones of methicillin-resistant Staphylococcus pseudintermedius (MRSP) have been identified in Europe and North America. They are designated multilocus sequence types (ST) 71 and 68 and contain staphylococcal chromosome cassette (SCCmec) types II-III and V(T), respectively. One notable difference between the two clones is a deletion in the mecI/mecR1 regulatory apparatus of ST 68 SCCmec V(T). This deletion in analogous methicillin-resistant Staphylococcus aureus (MRSA) results in more responsive and greater expression of the mecA encoded penicillin-binding protein 2a, and is associated with SCCmec types occurring in community-acquired MRSA lineages. The aim of this study was to characterize mec and bla regulatory apparatuses in MRSP and determine their effects on expression of mecA. Seventeen S. pseudintermedius isolates representing nine methicillin-resistant ST lineages were screened for the presence of the repressors blaI and mecI and sensors blaR1 and mecR1. The bla and mec operons for each isolate were sequenced and compared for homology between the repressor open-reading frames (ORF), sensor ORFs, and mecA promoter regions. A real-time reverse transcriptase PCR expression assay was developed, validated and applied to nine isolates determining the effect of oxacillin induction on mecA transcription. Significant differences were found in mecA expression between isolates with a full regulatory complement (mecI/mecR1 and blaI/blaR1) and those with truncated and/or absent regulatory elements. Isolates representative of European and North American MRSP ST regional clones have dissimilar mecA responses to oxacillin.

Short- and long-term cure rates of short-duration trimethoprim-sulfamethoxazole treatment in female dogs with uncomplicated bacterial cystitis.

Background Long‐duration beta‐lactam antibiotics are used for empirical treatment in female dogs with uncomplicated bacterial cystitis. However, women with bacterial cystitis are treated with short‐duration potentiated sulfonamides because longer courses of beta‐lactams result in lower cure and higher recurrence rates. Hypothesis/Objectives Short‐duration potentiated sulfonamide treatment is more efficacious than long‐duration beta‐lactam treatment in achieving clinical and microbiological cures in female dogs with uncomplicated bacterial cystitis. Animals Thirty‐eight client‐owned female dogs. Methods Randomized, double‐blinded, placebo‐controlled clinical trial. Dogs were treated with TMP‐SMX (15 mg/kg PO q12h for 3 days followed by a placebo capsule PO q12h for 7 days; Group SDS; n = 20) or cephalexin (20 mg/kg PO q12h for 10 days; Group LDBL; n = 18). Dogs were monitored for clinical and microbiological cure during treatment and at short‐ and long‐term follow‐up. Results No statistically significant differences were found between treatment groups in clinical cure rates after 3 days of treatment (89% SDS, 94% LDBL; P = 1.00) and 4 days (85% SDS, 72% LDBL; P = .44) or >30 days (50% SDS, 65% LDBL; P = .50) after conclusion of treatment or in microbiological cure rates 4 days (59% SDS, 36% LDBL; P = .44) or >30 days (44% SDS, 20% LDBL; P = .40) after conclusion of treatment. Conclusions and Clinical Importance We did not identify a difference in cure rates between short‐duration sulfonamide and long‐duration beta‐lactam treatments in female dogs with uncomplicated cystitis. Long‐term cure rates in both treatment groups were low. In some female dogs, “uncomplicated” bacterial cystitis may be more complicated than previously recognized.

Antimicrobial Susceptibility Profiles of Multidrug-Resistant Salmonella Anatum Isolated from Horses

Salmonella anatum is a common cause of salmonellosis, an important infectious disease in horses of all ages. These infections range in severity from asymptomatic colonization to serious life-threatening septicemia. In horses, the most common forms of clinical disease are acute enterocolitis with severe diarrhea and septicemia with or without diarrhea. Stress, transportation, hospitalization, antimicrobial therapy, colic, and surgery are risk factors associated with the development of clinical disease. Salmonella typhi-, murium is the serotype isolated most frequently from horses; other frequently isolated serotypes include S. agona, S. anatum, S. krefeld, S. newport, and S. typhimurium var. copenhagen. In the spring of 1991, multidrug-resistant (MDR) S. anatum was cultured from 2 septicemic foals referred for treatment to the University of Wisconsin Veterinary Medical Teaching Hospital (UWVMTH). Subsequently, 7 more isolates were cultured from horses treated at the UWVMTH and/or an Illinois veterinary clinic. The present report includes the antimicrobial susceptibility profiles of these MDR S. anatum. A total of 20 strains of S. anatum were examined for this study. Between April 1991 and August 1992, S. anatum was isolated from 3 septicemic foals and 3 adult horses referred for treatment to the UWVMTH. These animals were referred either from a clinic located in Illinois or by veterinarians from other locations in Illinois and Wisconsin. Two S. anatum isolates were obtained directly from the National Veterinary Service Laboratory (NVSL), Ames, IA. These isolates were from 2 additional horses treated at the Illinois clinic during the spring of 1991. In June 1991, 6 isolates of S. anatum were cultured from an environmental study of the Illinois clinic. Five isolates were obtained from stalls, 1 from a mineral oil bucket, and 1 from a horse being treated at the clinic. In addition, 5 different strains of S. anatum that were obtained at the UWVMTH between August 1986 and May 1991 from horses, cows, and the necropsy room drain were included in this study. These 20 isolates were the only strains of S. anatum cultured at the UWVMTH between August 1986 and August 1992. All strains were stored at -70 C. The isolates were identified using a commercial biochemical strip and were serotyped by NVSL and/or the Central Animal Health Laboratory, Madison, WI. All isolates were serotyped as S. anatum. An automated microbiology system was used to determine minimal inhibitory concentrations (MIC) of tetracy-