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PubMedDate not supplied

Diagnosis of avian mycobacteriosis: comparison of culture, acid-fast stains, and polymerase chain reaction for the identification of Mycobacterium avium in experimentally inoculated Japanese quail (Coturnix coturnix japonica).

In this study we compared culture, acid-fast stains, and polymerase chain reaction (PCR) for the detection of acid-fast organisms in fecal and tissue samples from Japanese quail (Coturnix coturnix japonica) that were experimentally inoculated intravenously with Mycobacterium avium. For culture, three different culture media (modified Herrold egg yolk with mycobactin; Lowenstein-Jensen [L-J]; and L-J with cyclohexamide, naladixic acid, and lincomycin) were tested to determine which medium had the greatest success in isolating mycobacteria. Acid-fast staining methods included Zichl-Neelsen (Z-N) and Truant. The PCR assay detected mycobacterial DNA with primers specific for the 65-kD heat shock protein gene. Culture was considered the "gold standard." Compared with other culture media, L-J yielded more positive cultures and greater numbers of colonies on positive tubes, and incubation times were shorter. Mycobacterium avium was isolated from all of the harvested tissue samples (liver, spleen, and intestine) of inoculated birds. Mycobacteria were isolated from 53% (69/130) of fecal samples from inoculated birds. As the disease advanced, fecal culture was positive on more culture days, indicating that the culture-positive rate was higher later in the course of the disease. Compared with culture, all of the laboratory methods had 100% specificity for the tissue samples. Sensitivities for the tissue samples were 82.6% (Z-N), 95.7% (Truant), and 100% (PCR). For the fecal samples, the specificity was >95% for all methods. Sensitivities compared with fecal culture were 7.2% (Z-N), 30.4% (Truant), and 20.3% (PCR). Tissue and fecal samples from the two control birds were negative for acid-fast organisms by any method. These results were comparable with clinical cases of avian mycobacteriosis where culture and PCR of tissue samples seem to be the most sensitive and specific laboratory tests and evaluation of fecal samples still remains challenging. On the basis of the results of this study, identification of mycobacteria in fecal samples from Japanese quail can be optimized by repeated cultures and Truant acid-fast staining of fecal smears.

Animals↗

PubMedDate not supplied

Inhibition of resistance plasmid transfer in Escherichia coli by ionophores, chlortetracycline, bacitracin, and ionophore/antimicrobial combinations.

Medicinal feed additives bacitracin, chlortetracycline (CTC), laidlomycin, lasalocid, and salinomycin inhibited the transfer of multiresistance-conferring plasmid pBR325 (Tet(r) Amp(r) Cp(r), 6.0 kb) into selected gram-negative strains with the use of an in vitro model. High concentrations of ampicillin-sensitive competence-pretreated Escherichia coli HB 101 cells were exposed to 10% (v/v) of 1:10 dimethyl sulfoxide/agent : water containing test mixtures for 0.5 hr prior to plasmid addition and transforming conditions. Transformation was inhibited for all antimicrobials and showed a positive association wich higher concentration. Additional testing of ionophore compounds separately and in combination with bacitracin, chlortetracycline, lincomycin, roxarsone, tylosin, and virginiamycin at representative feed concentrations demonstrated 80.6% to >99.9% inhibition (P < 0.001) of resistance transfer. Bacitracin alone inhibited transformation within the range of 50-500 ppm. No increase in resistance transfer was observed when poultry-derived and reference gram-negative isolates having low or no transformation efficiency were additionally tested. The results suggest that these compounds, at relevant concentrations used in animal feed, may interfere with cell envelope-associated DNA uptake channels or other transformation competence mechanisms. Through these mechanisms, ionophores and cell membrane-interactive feed agents such as CTC and bacitracin may act to inhibit resistance transfer mechanisms within poultry and livestock.

Bacitracin↗

PubMed1984

Quantitative analysis of the production of heat-labile enterotoxin by enterotoxigenic Escherichia coli.

A modified method of passive immune hemolysis (PIH) was applied to the quantitative assay of heat-labile enterotoxin (LT) produced by enterotoxigenic Escherichia coli. The method enabled the measurement of 0.2 to 1.2 ng LT. The production of LT by enterotoxigenic E. coli under various conditions was analyzed using the modified method. LT production was intense during the logarithmic growth phase and decreased during the stationary growth phase. Lincomycin (50 to 100 micrograms/ml) affected cell growth slightly, but enhanced production of LT until the late-stationary growth phase. About 90% of the LT produced was retained in the cell, and the rest was excreted into the culture medium. The initial pH of the culture medium affected LT production. Alkaline pH enhanced LT production, though growth was depressed. Aeration enhanced both growth and LT production.

Aerobiosis↗

PubMed1991

Pharmacokinetic interactions between theophylline and other medication (Part I).

Many drugs have been found to increase or decrease the clearance of theophylline, probably by interaction with one or more of the variants of the cytochrome P450 drug-metabolising system. Theophylline may be particularly susceptible to alteration of its clearance because of the particular form(s) of the P450 system involved, because its metabolism is saturable, and/or because 90% of its elimination is via metabolism. Its clearance has been found to be decreased (typically by around 25%, but often by far more) by erythromycin, troleandomycin (triacetyloleandomycin), roxithromycin, enoxacin, ciprofloxacin, pefloxacin, norfloxacin, ofloxacin, fluoroquinolone T-3262, pipemidic acid, cimetidine, etintidine, propranolol, verapamil, diltiazem, nifedipine, furosemide (frusemide), at least some anovulent agents, viloxazine, allopurinol, ticlopidine, idrocilamide, thiabendazole, disulfiram, influenza- and BCG-vaccination, interferon, and caffeine (half-life increase). In contrast, theophylline clearance (clearance/bioavailability) was found to be increased by isoprenaline (isoproterenol), terbutaline, some corticosteroids, phenytoin, phenobarbital, activated charcoal, felodipine moricizine, benzodiazepines and sulfinpyrazone - typically by about 25%, but sometimes by as much as 80% or more. For several of these concomitant medications, however, only some of the published studies can substantiate an influence, which may highlight the sensitivity of some interactions to particular experimental and/or clinical conditions, e.g. with terbutaline, erythromycin, ciprofloxacin, norfloxacin, ofloxacin, phenobarbital, cimetidine, verapamil, diltiazem, nifedipine, anovulents, allopurinol and influenza vaccination. Moreover, reports both of inhibition and of induction of theophylline clearance by each of rifampicin and isoniazid have appeared. Nevertheless, under investigation many medications have not been found to perceptibly influence theophylline disposition kinetics, e.g. ephedrine, orciprenaline (metaproterenol), prednisone, prednisolone, temelastine, terfenadine, mequitazine, picumast, repirinast, josamycin, midecamycin, miocamycin, spiramycin, amoxicillin, ampicillin, cefalexin, cefaclor, ceftibuten, cotrimoxazole (trimethoprim plus sulfamethoxazole), tetracycline, doxycycline, lomefloxacin, fluoroquinolones NY-198 and AM-833, nalidixic acid, lincomycin, metronidazole, certain antacids, ranitidine, roxatidine, pirenzepine, rioprostil, metoclopramide, metoprolol, atenolol, nadolol, medroxyprogesterone, dextropropoxyphene (propoxyphene), piroxicam, ozagrel, mebendazole and ascorbic acid.(ABSTRACT TRUNCATED AT 400 WORDS)

Adrenal Cortex Hormones↗

PubMed1975

Antibacterial drugs today. I.

Since the development of the sulphonamides in the 1930s and the subsequent development of antibiotics from the 1940s onwards, there have now been many drugs developed which are capable of chemotherapeutic activity in a patient infected by a susceptible micro-organism. This review is concerned with precise descriptions of important groups of antimicrobial drugs, with emphasis being placed on the more recently developed drugs. With each group of drugs the pharmacology, major therapeutic indications, dosages and adverse reactions are discussed. Part I of the article discusses the sulphonamides, the natural and semi-synthetic penicillins, cotrimoxazole, chloramphenicol, tetracyclines, the macrolides, lincomycin and clindamycin, fusidic acid, and the urinary antiseptics. The place of each in therapy is defined.

Anti-Bacterial Agents↗

PubMed2005

Mechanisms of drug resistance in Mycoplasma pneumoniae.

Mycoplasma pneumoniae is a pathogenic mycoplasma responsible for respiratory tract infections in humans, occurring worldwide in children and adults. This review briefly focuses on its antibiotic susceptibility profile and on the development of acquired resistance for this microorganism. The lack of a cell wall in mycoplasmas makes them intrinsically resistant to beta-lactams and to all antimicrobials which target the cell wall. Intrinsic resistance related to specific mycoplasma species concerns essentially the acrolide-lincosamide-streptogramin-ketolide (MLSK) antibiotic group. M. pneumoniae is susceptible to all MLSK antibiotics, except to lincomycin. Among the three antibiotic classes used for the treatment of mycoplasmal infections including tetracyclines, MLSK group, and fluoroquinolones, macrolides and related antibiotics are the drug of choice for respiratory infections caused by M. pneumoniae. Both target alterations and efflux mechanisms implicated in acquired antibiotic resistance have been described in mycoplasmas either by genetic mutation or transfer of new genes carried by transposons. At present, M. pneumoniae remains greatly susceptible to antibiotics, but as this mycoplasma is difficult to isolate, the number of clinical strains tested is limited and the occurrence of acquired resistance not well documented. However some strains having acquired resistance to MLSK have been decribed in vivo and erythromycin-resistant isolates are spreading now in Japan. To date, no clinical isolates resistant to fluoroquinolones or tetracyclines have been described in the literature, but some strains having acquired resistance to both classes have been selected in vitro. Molecular diagnosis of this acquired resistance has been related to target alterations, in ribosome for macrolides and tetracyclines, or in topoisomerase II genes for fluoroquinolones.

Adult↗

PubMedDate not supplied

[Pseudomembranous colitis during antibiotic therapy].

INTRODUCTION: The use of antibiotics is commonly accompanied by diarrhea: idiopathic diarrhea with a benign process and diarrhea caused by Clostridium difficile and pseudomembranous colitis. Clostridium difficile colonizes the gastrointestinal tract and produces a toxin in cases when normal flora is suppressed by antibiotics. Pseudomembranous colitis most frequently appears after application of clindamycin, lincomycin, ampicillin, cephalosporins and other antibiotics. Diagnosis is established after rectoscopic findings of adherent pseudomembrane and pathohistological verification. The diagnosis is confirmed if there is evidence of Cl. difficile toxin in feces. CASE REPORT: We report about the clinical course of two patients with antibiotic-associated colitis. The diagnosis were made by clinical examinations, rectoscopy and pathohistologic verification of biopsy specimen of the intestinal mucosa. Neutralization test was not done due to technical reasons. Patients were treated with metronidazole. Unwanted side-effects of metronidazole therapy were not observed. DISCUSSION: Both our patients confirmed that they previously used different antibiotics. In the first case, diarrhea appeared during the antibiotic therapy, and in the second case, after finishing it. After antibiotic use, diarrhea appears in 5.30% cases, but fortunately pseudomembranous colitis is rare. However, taking into consideration that pseudomembranous colitis has a severe course and requires urgent treatment, one has to consider the possibility of pseudomembranous colitis when diarrhea appears during and after antibiotic use in order to initiate adequate therapy.

Adult↗

PubMed2002

Bacterial colonization of intravenous catheters in young dogs suspected to have parvoviral enteritis.

OBJECTIVE: To determine the prevalence of bacterial colonization of IV catheters among young dogs suspected to have parvoviral enteritis, to identify the organisms responsible for catheter colonization, and to determine the antimicrobial susceptibility of organisms that were obtained. DESIGN: Case series. ANIMALS: 100 dogs. PROCEDURE: Catheters were aseptically removed when fluid therapy was discontinued, the catheter was replaced, or the dog died. The distal tip of the catheter was cut off, split open, and vortexed with sterile saline (0.9% NaCl) solution. The saline solution was plated on culture plates, which were then incubated and examined for bacterial growth every 24 hours for 72 hours. All bacteria cultured were identified, and antimicrobial susceptibility was determined. RESULTS: Bacteria were isolated from 22 catheters. Most bacteria that were isolated were of gastrointestinal tract or environmental origin (Serratia odorifera, S. liquefaciens, S. marcescens, Acinobacter anitratus, Citrobacter freundii, Klebsiella pneumoniae, K. oxytoca, Escherichia coli, Enterobacter spp). Only 2 gram-positive organisms were isolated (Staphylococcus intermedius and Streptococcus spp). High percentages of organisms were resistant to penicillin, lincomycin, cloxacillin, erythromycin, and cephalexin. Percentages of organisms resistant to amikacin, enrofloxacin, chloramphenicol, potentiated sulfonamides, and amoxicillin-clavulanic acid were low. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that IV catheters may be colonized with bacteria in 22% of young dogs suspected to have parvovirus infection.

Animals↗

PubMed2003

Antimicrobial resistance of bacteria isolated from dairy cow milk samples submitted for bacterial culture: 8,905 samples (1994-2001).

OBJECTIVE: To determine whether antimicrobial resistance patterns of major mastitis pathogens isolated from milk samples from dairy cows have changed over time. DESIGN: Retrospective study. SAMPLE POPULATION: 8905 bacterial isolates obtained from milk samples submitted to the Wisconsin Veterinary Diagnostic Laboratory between January 1994 and June 2001. PROCEDURE: Antimicrobial susceptibility was determined by means of the Kirby-Bauer disk diffusion method. Logistic regression was used to determine whether percentages of isolates resistant to various antimicrobials changed over time. RESULTS: For the gram-positive mastitis pathogens, percentages of isolates resistant to various flactam antimicrobials did not increase over the course of the study. Percentage of Staphylococcus aureus isolates resistant to penicillin decreased from 49 to 30%; percentage of Streptococcus isolates resistant to penicillin decreased from 6 to 1%. Percentage of isolates resistant to erythromycin increased for S aureus, Escherichia coli, Enterobacter spp, Enterococcus spp, and Pasteurella spp. Percentage of isolates resistant to lincomycin increased for S aureus and Staphylococcus spp. Percentage of coagulase-negative Staphylococcus isolates resistant to pirlimycin increased from 6 to 19%. For several pathogens, percentages of isolates resistant to sulfisoxazole and to trimethoprim-sulfamethoxazole decreased. No pathogens had a significant increase in the percentage of isolates resistant to novobiocin-penicillin. CONCLUSIONS AND CLINICAL RELEVANCE: Results did not indicate a trend toward increased antimicrobial resistance among mastitis pathogens isolated from milk samples from dairy cows between 1994 and 2001. Reduced resistance to flactam antimicrobials was identified for several gram-positive mastitis pathogens.

Animals↗

PubMed2003

Molecular ecological analysis of porcine ileal microbiota responses to antimicrobial growth promoters.

Cultivation-independent microbial molecular ecology approaches were used to examine the effects of antibiotic growth promoters on the pig ileal microbiota. Five-week-old barrows were fitted with a simple T-cannula at the distal ileum. Three diets meeting or exceeding the minimum nutrient requirements were fed for 5 wk and supplemented as follows: 1) negative control (no antibiotic; n = 5), 2) continuous tylosin administration (n = 5), and 3) an antibiotic rotation sequence (wk 1, chlorotetracycline sulfathiazole penicillin; wk 2, bacitracin and roxarsone; wk 3, lincomycin; wk 4, carbadox; wk 5, virginiamycin; n = 5). Ileal luminal contents were collected for DNA isolation at the end of each of the 5 wk of the testing period. The V3 region of 16S rDNA was amplified by PCR and analyzed via denaturing gradient gel electrophoresis (DGGE) and quantitative polymerase chain reaction (qPCR). Resulting PCR-DGGE band numbers (bacterial species) were counted, and the banding patterns analyzed by calculating Sorenson's pairwise similarity coefficients (C(S)), an index measuring bacterial species in common among samples. Band numbers and total bacterial DNA concentrations decreased (P < 0.05) temporally in antibiotic-treated pigs compared with controls. Comparisons between treatments yielded low intertreatment C(S) indices, indicating treatment-dependent alterations in banding patterns, whereas intratreatment comparisons revealed increased homogeneity in antibiotic-treated vs. control pigs. Sequence analysis of treatment-specific bands identified three Lactobacillus, one Streptococcus, and one Bacillus species that were diminished with antibiotic rotation treatment, whereas tylosin selected for the presence of L. gasseri. Lactobacillus-specific qPCR was performed and analyzed as a percentage of total bacteria to further evaluate the effects of antibiotic administration on this genus. Total bacteria were decreased (P < 0.05) by tylosin and rotation treatments, whereas the percentage of lactobacilli increased (P < 0.05) by d 14 and through d 28 in tylosin-treated pigs. The decrease in total bacteria by antibiotics may reduce host-related intestinal or immune responses, which would divert energy that could otherwise be used for growth. Conversely, the ability of tylosin to improve animal growth may relate to its apparent selection for lactobacilli, commensals known to competitively exclude potentially pathogenic species from colonizing the intestine.

Animals↗

PubMed1983

Disinfection of human heart valve allografts with antibiotics in low concentration.

Antibiotic disinfection of allograft heart valves is now an established procedure. A new low-concentration, broad-spectrum mixture of antibiotics was formulated and used successfully to disinfect 58 of 60 human aortic and pulmonary valves after 48 h exposure at 4 degrees C. The antibiotics included were cefoxitin 240 mcg/ml, lincomycin 120 mcg/ml, polymyxin B 100 mcg/ml, vancomycin 50 mcg/ml and amphotericin B 25 mcg/ml. Microorganisms isolated from experimental tissue and from clinical valves before treatment were tested for sensitivity to these antibiotics and were found to be sensitive to one or more. One isolate of Pseudomonas spp. showed decreased sensitivity to polymyxin B, and was found to have a minimum bactericidal concentration of 70 mcg/ml. Results indicated this antibiotic mixture had superior antibacterial efficiency to that in routine clinical use for the past 13 yr.

Anti-Bacterial Agents↗

PubMed1987

The reduction of sulphinpyrazone and sulindac by intestinal bacteria.

1. Incubation of human or rabbit faeces with sulphinpyrazone gave greater reduction under anaerobic than under aerobic conditions. Reduction of sulindac by human faeces was more extensive than that of sulphinpyrazone. 2. Growth of mixed cultures of intestinal bacteria in nutrient media containing antibiotics produced a marked inhibition in their ability to reduce sulphinpyrazone. Sulphide formation was inhibited by metronidazole and lincomycin for human faeces and by tetracycline for rabbit faeces/caecal contents. 3. The formation of the sulphides of sulindac and sulphinpyrazone ex vivo was decreased in faeces from patients treated with metronidazole. Metronidazole, but not tetracycline, decreased the extent of reduction of sulphinpyrazone by rabbits in vivo. No reduction of either substrate occurred on incubation with ileostomy effluent. These data indicate that anaerobic intestinal bacteria are important in the reduction of these sulphoxide-containing drugs. 4. However, when incubated anaerobically with over 200 strains of bacteria isolated from human faeces, sulphinpyrazone was reduced by most of the aerobic but not the anaerobic organisms. Sulindac was reduced more extensively by the same aerobes and by some anaerobes. 5. The discrepancy between the apparent importance of anaerobes in vivo and in vitro may be due to their very large number present in the hind gut and to the production of an anaerobic environment suitable for the enzymic activity of other organisms, such as aerobes or facultative anaerobes.

Animals↗

PubMed1992

Antimicrobial agents induce monocytes to release IL-1 alpha, IL-6, and TNF, and induce lymphocytes to release IL-4 and TNF tau.

Evaluation was carried out on the action of different antibiotics on the release of cytokines. Experiments were done in vitro on monocytes and on human lymphocytes. Results show that the majority of the antibiotics tested are able to induce the release of one or more cytokines from their respective producing cells. Among the beta-lactams the most active were the cephalosporins (cephalexin, cefamandol, ceftazidin, and a sulbactam-ampicillin combination) in inducing the release of TNF, IL-1 alpha, and IL-6 from monocytes, and releasing IL-4 and IFN-tau from lymphocytes. The sulbactam-ampicillin combination and cefamandole were extremely active in the production of IFN-tau. Among the lincosamides, clindamycine notably stimulated the release of TNF and IL-6, while lincomycine induced a notable increment of IL-4 from monocytes. Teicoplanin is a very strong inducer of TNF, IL-1 alpha and IL-6.

Anti-Bacterial Agents↗

PubMed2006

Short communication: antimicrobial drug susceptibility of Staphylococcus aureus from subclinical bovine mastitis in Italy.

The antimicrobial susceptibility of 68 Staphylococcus aureus isolates collected during 2004 from milk of cows affected by subclinical mastitis was examined. The antimicrobial agents tested were the beta-lactams, penicillin G, amoxicillin, ampicillin, cloxacillin, amoxicillin + clavulanate, cephalonium, and cefoperazone; and other drugs including lincomycin, oxytetracycline, doxycycline, and kanamycin. Minimum inhibitory concentrations recorded show that only certain beta-lactamase-resistant penicillins (specifically cloxacillin) or penicillin combinations (amoxicillin + clavulanate) were consistently effective against Staph. aureus, whereas the other beta-lactam derivatives and drugs from other pharmacological groups were either moderately effective or ineffective. Thus, beta-lactamase-resistant penicillins are to be considered the antimicrobial agents of choice for treatment of bovine mastitis resulting from infection by Staph. aureus.

Animals↗

PubMed1993

Antimicrobial susceptibility of bifidobacteria.

The antimicrobial susceptibility of 37 strains of bifidobacteria to 18 antimicrobial agents was determined by a macrodilution broth method. Most of the strains used were isolated from commercial yogurts and starters. Tested organisms were usually sensitive to Gram-positive spectrum antibiotics (bacitracin, erythromycin, lincomycin, and vancomycin), and most of the organisms were inhibited by a concentration < 1.56 micrograms/ml. Erythromycin was the most active agent; all strains were inhibited by < .19 microgram/ml. beta-Lactam antibiotics (penicillin G, ampicillin, methicillin, and cephalothin), showing a wide range of minimum inhibitory concentration, were less effective than Gram-positive spectrum antibiotics. Most strains were somewhat resistant to cephalothin, exhibiting inhibition at concentrations of 6.25 to 25.0 micrograms/ml. Test organisms were most resistant to kanamycin, neomycin, paromomycin sulfate, nalidixic acid, and polymyxin B sulfate; inhibition occurred only at > or = 50 micrograms/ml, and strains were somewhat less resistant to gentamicin and streptomycin. Susceptibility to nitrofurantoin and tetracycline was variable; minimum inhibitory concentrations ranged from 1.56 to 50.0 and .39 to 50.0 micrograms/ml, respectively, but chloramphenicol had a narrow range from 1.56 to 6.25 micrograms/ml.

Aminoglycosides↗

PubMed1980

Compatibility and anticoccidial activity of lasalocid in combination with roxarsone and antibiotics against Eimeria mixed infection in chicks.

Lasalocid at the concentration of .0075% (68 g/ton) with and without roxarsone 45.4 g/ton was fed in combination with the growth promotants bacitracin methylene disalicylate 200 g/ton, bambermycins 2 g/ton, lincomycin 4 g/ton, nosiheptide 2.5 g/ton, zinc bacitracin 200 g/ton g/ton, and virginiamycin 20 g/ton exhibited a high degree of anticoccidial activity against mixed Eimeria infection in chickens in 9 day challenged battery trials. In these short term challenge trials chicks fed lasalocid, and the lasalocid growth promotant combinations, performed significantly better (P < .05) for growth and anticoccidial efficacy than those fed the growth promotants alone, and the infected, unmedicated controls. In almost all instances, the lasalocid-roxarsone-antibiotic combinations allowed for numerical increases in gains, improvement in feed conversion, and numerical decreases in lesions (in some cases, statistically significant (P < .05) over chicks fed lasalocid alone and/or the lasalocid antibiotic combination. The growth promotants did not interfere with the anticoccidial activity of lasalocid. The growth promotants fed alone exhibited no anticoccidial activity. However, when roxarsone was combined with the antibiotics, the combination resulted in numerically improved performance, reduced mortality, and in most instances, statistically significant decreases in lesions (P .05) over the infected, unmedicated control.

Animals↗

PubMed1982

Influence of salinomycin on antimicrobial resistance of coliforms and streptococci from broiler chickens.

An experiment was conducted to evaluate antimicrobial resistance of coliforms and streptococci isolated from feces of chickens fed salinomycin. Two groups of 20 chickens were fed either a control feed or feed supplemented with 80 g/ton salinomycin. Chicken fecal coliforms and streptococci were isolated at 5, 15, 19, 22, 26, 33, 40, and 47 days of age and their resistance to 11 or 12 antibacterial agents (coliforms and streptococci, respectively) were determined in both groups of chickens. Salinomycin significantly reduced the number of coliforms resistant to sulfadiazine and reduced the number of streptococci resistant to erythromycin and lincomycin. Streptococci from birds fed salinomycin had lower minimum inhibitory concentrations for streptomycin. No streptococci isolates developed resistance to salinomycin. Coliforms from birds fed salinomycin had more (P less than .05) resistance patterns involving two, five, and six drugs. Numbers of coliforms resistant to streptomycin, ampicillin, carbenicillin, and cephalothin were greater (P less than .05) from birds fed salinomycin.

Animals↗

PubMed2002

Prevalence of coagulase-negative staphylococci in bovine mastitis in Zimbabwe.

This study was carried out to determine the prevalence of coagulase-negative staphylococci in clinical and subclinical mastitis in commercial and small-scale farms in Zimbabwe. Thirty five quarter milk samples from clinical mastitis cases and 371 quarter milk samples from cows with subclinical mastitis were cultured for bacterial pathogens. The most frequent pathogens isolated in clinical mastitis were the enteric bacteria (31.4%), followed by coagulase negative staphylococci (22.9%) and then Staphylococcus aureus (17.1%), whereas in subclinical mastitis S. aureus (34.2%) and coagulase-negative staphylococci were (33.2%) the most common. Bacillus species were only isolated in milk samples from subclinical mastitis. Coagulase-negative staphylococci were observed in mixed infections with other bacteria in only 2.2 of the 406 milk samples from clinical and subclinical mastitis where they were isolated together with Bacillus species in 6 of the 9 mixed infection cases. About 95% of the milk samples from which 131 coagulase-negative staphylococci were isolated had correspondingly high somatic cell counts. The coagulase-negative staphylococci isolated most frequently were S. chromogenes (7.9%), S. epidermidis (7.4%) and S. hominis (5.9%). They were all associated with high somatic cell counts. All the coagulase-negative staphylococci isolates were susceptible to cloxacillin and erythromycin, and more than 90% of the isolates were susceptible to neomycin, penicillin and streptomycin. The highest resistance was to tetracycline (17.6%), followed by lincomycin (13.7%). About 8% of the isolates were resistant to both penicillin and streptomycin.

Animals↗