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Biomedical subjects

R Munro

Publications and source records attributed to R Munro.

At least 91 records · Page 5Linked to original sources
PubMed1989

A national survey of antimicrobial resistance in Staphylococcus aureus in Australian teaching hospitals.

An extensive survey of the in-vitro susceptibility of clinical isolates of Staphylococcus aureus to 18 antimicrobial agents was conducted over three separate periods during 1986-1987 in 14 teaching hospitals in major Australian cities. The survey aimed to document the prevalence of resistance to a wide variety of drugs that are important as antistaphylococcal agents or as epidemiological markers. More than 7500 isolates were examined. Nationally, the prevalence of resistance was 85.3% to penicillin G, 14.4% to methicillin, 14.0% to amoxycillin/clavulanate, 9% to cephalothin, 5.4% to cephamandole, 9.9% to cefotaxime, 25.0% to erythromycin, 11.2% to clindamycin, 21.7% to tetracycline, 13.0% to gentamicin, 1.9% to amikacin, 5.8% to chloramphenicol, 18.3% to trimethoprim, 0.6% to rifampicin, 3.0% to fusidic acid and 1.2% to novobiocin. For none of the strains was resistance to vancomycin confirmed by minimal-inhibitory-concentration determination. A high proportion of the resistances was harboured in methicillin-resistant Staph. aureus, except for resistance to penicillin G, erythromycin and tetracycline. The prevalence of methicillin resistance varied widely among the states: 25.2% in Queensland, 23.5% in Victoria, 12.6% in New South Wales/the Australian Capital Territory, 11.3% in South Australia and 0.4% in Western Australia. Isolates from blood cultures were slightly-more susceptible to antimicrobial agents than were isolates from other body sites. Six common profiles of resistance to penicillin G, methicillin, erythromycin, clindamycin and tetracycline accounted for more than 95% of the isolates that were tested against all five agents. Vancomycin remains the most important antistaphylococcal drug in areas where resistance to methicillin is common.

Anti-Bacterial Agents↗
PubMed1989

Laboratory diagnosis of intravascular catheter associated sepsis.

Many different methods have been employed to aid in the laboratory diagnosis of intravascular catheter associated infection. However, because of differences in patient populations, the definition of catheter sepsis and types of catheters, comparison of these studies is difficult. Of even more fundamental importance, the question of the pathogenesis of intravascular catheter associated sepsis (i.e. whether the microorganisms migrate to the intravascular space via the internal or external surface of the catheter) has not been resolved and is the subject of ongoing controversy. Semiquantitative culture of catheter tips would appear the easiest and most labour-efficient method available at present to diagnose catheter related infection. With central vein catheter tips, however, a cut-off level below 15 CFU per plate should be adopted as indicating a positive test result, particularly in patient populations with a high prevalence of catheter associated infection. Methods for non-quantitative broth culture of catheter tips are likely to be more sensitive than the semiquantitative method, but are less specific. Quantitative broth methods improve the specificity, but because of the labour costs involved appear not to offer much advantage over the semiquantitative method in the routine clinical laboratory. Many studies have shown that organisms are more frequently seen on staining than recovered by culture of intravascular catheters. Further studies of intravascular cathether sepsis should include a catheter staining method in addition to culture. Aspiration and culture of blood through an intravascular catheter appears to be reasonably specific in diagnosing the presence of infection on the catheter tip, but is only of low sensitivity (20-40%) in the absence of associated bacteremia.

Catheterization, Central Venous↗
PubMed1989

Aeromonas septicemia: relationship of species and clinical features.

Thirteen patients with Aeromonas species septicemia were seen at Westmead Hospital between 1983 and 1987. In 10 patients (77%) septicemia was caused by A. sobria, and in 3 (23%) by A. hydrophila, A. caviae was not isolated. Chronic underlying illness was present in 10 patients (77%), hematological malignancy being the most common (46%). The average age of the patients was 65.8 years. Seven patients (54%) presented with clinical sepsis, diarrhea and abdominal pain. The biliary tract, lung and soft tissue were other primary sites of infection. Nosocomial infection occurred in 5 patients (38%). Cross-infection was not seen. Contact with fresh water or fish was observed in only 2 patients (15%). The majority of cases occurred in the warmer months of the year. The overall mortality was 46%. All isolates of Aeromonas species were resistant to ampicillin 8 mg/L. Ten isolates were resistant to tobramycin 1 mg/L, and 3 to tobramycin 4 mg/L. In contrast, 3 isolates were resistant to gentamicin 1 mg/L, and none to 4 mg/L. The isolates showed a varied pattern of resistance to other antibiotics tested, but all were susceptible to piperacillin 64 mg/L, imipenem 4 mg/L, ciprofloxacin 1 mg/L, and amikacin 16 mg/L.

Adult↗
PubMed1988

Meningococcal serogroups in New South Wales, 1977-1987.

Data are presented on serogroups of meningococci (Neisseria meningitidis) that were submitted to Westmead Hospital and The Children's Hospital, Camperdown, from patients in Sydney and in rural areas of New South Wales, from January 1, 1977 to December 31, 1987. One hundred and ten organisms that were isolated from cerebrospinal fluid or from blood were examined. All organisms were isolated from sporadic cases of meningococcal disease. Patients in the zero-to-two-years' age-group were affected most commonly, but 36.3% of isolates were from older children and adults. The distribution of serogroups was as follows: serogroup B, 43.6; serogroup A, 28.2%; serogroup C, 10.0%; serogroup W135, 8.2%; serogroup Y, 4.5%; and serogroup Z, 0.9%. The isolates that were serogrouped by us represented approximately half the cases of meningococcal meningitis that were notified in New South Wales during this period. Serogrouping of meningococcal isolates is very important in order to follow epidemiological trends in the disease and to monitor the serogroups that cause outbreaks, where vaccination of contacts may be indicated. Our laboratories are prepared to receive isolates for serogrouping and antibiotic sensitivity testing from across New South Wales.

Adolescent↗
PubMed1988

Comparison by experimental infections in cattle of a Dictyocaulus species occurring naturally in red deer and a dictyocaulus of bovine origin.

Dictyocaulus species larvae were obtained from young red deer which had become infected on pastures considered to be carrying the Dictyocaulus species indigenous to the red deer of Scotland. These larvae were cultured to third stage and transmitted to five bovine calves. Five other bovine calves were infected with third stage Dictyocaulus viviparus larvae of bovine origin. Microscopic appearances of both groups of larvae were indistinguishable and their lengths were similar. Results indicated that the Dictyocaulus species derived from deer induced milder though similar clinical and pathological responses in cattle than did the D viviparus derived from cattle. It was concluded that there are strains of different pathogenicity within the species D viviparus, that the deer derived Dictyocaulus species was a strain of D viviparus, and that the hazards to animal health associated with infection by D viviparus in farming systems where red deer and cattle may graze alternately are likely to be acceptable.

Animals↗
PubMed1988

Susceptibility of anaerobic bacteria to antimicrobial agents.

The antimicrobial susceptibility of 1,117 clinical isolates of anaerobic bacteria was determined by the agar dilution technique. Metronidazole was the most active agent; only Propionibacterium acnes and Actinomyces sp. isolates were resistant. Clindamycin and chloramphenical were the next most effective agents. Beta-lactam antibiotics, with the exception of penicillin, were active against most anaerobes other than the Bacteroides fragilis group. At a breakpoint of 8 mg/l, 25% of Fusobacterium spp. and 30% of the non-fragilis Bacteroides spp. were resistant to penicillin. The highest resistance to beta-lactams was seen in the B. fragilis group. Within the indole-positive members of the group, resistance rates of 71% were seen for cefoxitin, 49% for moxalactam, 79% for cefotaxime, 22% for piperacillin and 89% for penicillin. We conclude that metronidazole has the most predictable in vitro activity against common clinical anaerobic isolates and that resistance to beta-lactams was frequent and of potential clinical importance as these latter agents are frequently used in the prophylaxis and therapy of mixed anaerobic infections.

Anti-Bacterial Agents↗
PubMed1988

An evaluation of a rapid latex test for the diagnosis of Clostridium difficile-associated diarrhea.

We present here the results of an evaluation of a rapid latex test for detection of Cl. stridium difficile-associated in comparison with our standard cytotoxin assay and culture for C. difficile. Some 515 diarrheal stools were examined. C. difficile was cultured from 70 specimens (13.5%); 53 specimens (10.2%) were positive with the latex test, and 50 (9.6%) by cytotoxin assay. The latex test did not differ significantly from the cytotoxin assay in sensitivity or specificity compared to culture results. There was also no significant difference in the specificity of the latex test compared to cytotoxin assay in patients in whom the diagnosis of C. difficile-associated diarrhea was negative. Positive and negative predictive values of the latex test for C. difficile-associated diarrhea were similar to those of cytotoxin assay. The latex test thus appears to be a rapid and practical test for the laboratory diagnosis of C. difficile-associated diarrhea. To optimize specificity and sensitivity its use should be restricted to patients where the diagnosis is strongly suspected and a rapid answer is required. As it does not distinguish between toxigenic virulent C. difficile strains and non-toxigenic avirulent strains, it would seem prudent to confirm positive results subsequently by demonstrating in-vivo or in-vitro cytotoxin production.

Adolescent↗
PubMed1987

Rapid diagnosis of intravascular catheter-related sepsis.

The use of Gram-stained "impression smears" of the external surface of intravascular catheters for rapid detection of catheter-associated infection was studied. Gram's stain results of 322 catheters were correlated with clinical episodes of systemic sepsis and semiquantitative cultures of the catheters. Organisms were seen on Gram's stain of 82 catheters, 37 of which were positive on semiquantitative cultures (greater than or equal to 15 colonies per plate). Catheter-related bacteremia occurred on three occasions. All three catheters showed numerous organisms on Gram's stain, although one was negative on semiquantitative culture. All five catheters, in place during bacteremic episodes that were unrelated to catheter infection, were negative on Gram's stain. If the presence of any organisms on Gram's stain was taken as a positive test result, the sensitivity of Gram's stain in predicting the result of semiquantitative culture was 83%, the specificity was 81%, and the predictive value of a positive and negative culture was 44% and 96%, respectively. Slides took two to five minutes to examine microscopically. Gram-stained impression smears of intravenous catheters can be made by a simple, inexpensive, and rapid technique that is accurate in diagnosing catheter-related infection. However, in this study in which a relatively low prevalence of catheter-related bacteremia occurred, the positive predictive value of the Gram's stain result in the diagnosis of catheter-related bacteremia, in contrast to catheter colonization, was low. Only in a patient group with a high prevalence of catheter-related bacteremia would the test be likely to have a high positive predictive value. Thus, selectivity should be exercised in the application of this method.

Catheterization↗
PubMed1986

Acute myopathy in horses at grass in east and south east Scotland.

A myopathy of horses at grass in east and south east Scotland was recognised in the autumn and winter of 1984 and the spring of 1985. The clinical signs resembled those of paralytic myoglobinuria. Grossly increased creatine kinase activities and the passage of dark brown urine were consistent features. However, the horses were not in training, most of them died and the muscles affected were those of posture and respiration rather than movement. The condition may be unrelated to nutritional myopathy because all the cases had adequate levels of alpha-tocopherol although their selenium status varied from normal to deficient. The clinical and pathological findings in 12 cases are presented and the differential diagnosis and possible aetiologies discussed.

Acute Disease↗
PubMed1986

Propionibacterium acnes infection in neurosurgical patients. Experience with high-dose penicillin therapy.

Propionibacterium acnes is an underestimated but significant cause of cerebrospinal fluid (CSF) infection after neurosurgical procedures and in the presence of prosthetic devices. The most effective therapy for such infections has not been defined. We report here our experience with the use of high-dose penicillin in the treatment of six patients with postoperative infection which was caused by P. acnes. All patients received 3-4 million units of penicillin by the intravenous route every four hours, in combination with surgical drainage and removal of prosthetic devices where appropriate. All but one of the patients recovered from their infection. The remaining patient responded to penicillin but died of a massive intraventricular haemorrhage after 12 days. Isolates of P. acnes had minimal inhibitory concentrations to penicillin that ranged from 0.03-0.12 mg/L. No adverse reactions to penicillin were recorded. We conclude that high-dose intravenous penicillin therapy, in combination with surgical drainage and removal of foreign bodies, constitutes appropriate therapy for CSF infections that are due to P. acnes.

Combined Modality Therapy↗
PubMed1986

Is semiquantitative culture of central vein catheter tips useful in the diagnosis of catheter-associated bacteremia?

Semiquantitative culturing of catheter tips has been used as an index of catheter-related bacteremia. As the sensitivity and predictive values of this test have not been determined, we studied 780 tips from central vein catheters inserted into 440 critically ill patients in an intensive care unit. The results were correlated with clinical data for 30 bacteremic episodes which occurred in these patients, 14 of which were catheter related. When five or more colonies per plate were taken as a positive result, the sensitivity of the method was 92%, and the specificity was 83%. Although the predictive value of a negative result was excellent (99.8%), the predictive value of a positive result was low (8.8%) in our patient population, which had a relatively low incidence of catheter-related bacteremia (2%). We conclude that a semiquantitative culture technique is useful in the diagnosis of bacteremia associated with central vein catheters.

Bacteria↗
PubMed1986

Evaluation of lysis filtration as an adjunct to conventional blood culture.

A lysis filtration system was used in conjunction with conventional broth culture for 1112 blood cultures. The system, which entailed collection of 5 ml of blood into bottles containing 50 ml isotonic phosphate buffer, Tween 20, and Rhozyme with subsequent filtration using a 0.45 micron Millipore field monitor, was simple and economical to use. Positive results were obtained earlier than those obtained with conventional broth cultures, and almost twice as many fungi and yeasts were isolated. Some fastidious organisms such as Haemophilus influenzae and Streptococcus pneumoniae however, were not recovered from the lysis system, and contaminants in lysis cultures were three times as common as in conventional culture. The number of positive cultures was also adversely influenced by incubation of the blood lysis mixture overnight before filtration. We conclude that this lysis filtration system is useful as an adjunct to conventional broth culture in selected patients in cases in which filtration can be carried out soon after collection.

Bacteria↗
PubMed1986

Biliary sepsis. Reviewing treatment options.

Bactobilia is a frequent accompaniment of obstruction in the biliary tract, organisms present being normal intestinal aerobes and anaerobes. Bacterial colonisation of the bile may occur asymptomatically, may predispose to infection postoperatively, or may be associated with an attack of acute cholecystitis, occurring secondary to obstruction. The choice of an antimicrobial regimen for biliary infection should take into account the expected antibiotic sensitivities of organisms colonising bile, whether biliary obstruction or bacteraemia is present, and the activity of the antibiotic in bile. Often, high biliary concentrations of an antibiotic cannot be achieved due to obstruction, and in many cases high blood and tissue concentrations are of greater importance. Surgical prophylaxis should be reserved for patients at high risk of bactobilia (e.g. the elderly), when obstruction is present, for immunosuppressed patients, and those with artificial heart valves. A single perioperative dose of a 'first' or 'second generation' cephalosporin, gentamicin, or co-trimoxazole is effective. Antibiotic therapy for acute cholecystitis should be instituted if there is evidence of systemic toxicity, when surgery is to be delayed, or in patients with identified risk factors for bactobilia. Ampicillin or a cephalosporin may be appropriate in less severe disease, while in seriously ill patients, an aminoglycoside or cephalosporin with metronidazole or clindamycin is appropriate. Oral regimens include amoxycillin, an oral cephalosporin, or co-trimoxazole, in combination with metronidazole. In acute cholangitis, systemic therapy similar to that recommended for acute cholecystitis is indicated. Patients with recurrent cholangitis may have relatively antibiotic-resistant bacteria and efforts should be made to obtain a bacteriological diagnosis. Long term suppressant therapy with oral agents such as amoxycillin, cephalexin, or co-trimoxazole may be tried.

Anti-Bacterial Agents↗
PubMed1986

In vitro antibacterial activity of enoxacin (CI-919).

Antibacterial activity of enoxacin was evaluated against more than 3,700 clinical isolates using the agar-dilution method and an inoculum of 10(4)-10(5) cells per site. For comparison other antibiotics appropriate for each species were also included. For most enterobacteria and for Staphylococcus aureus, Staphylococcus epidermidis and Pseudomonas aeruginosa, the MIC90 of enoxacin was below 2 mg/l. Serratia marcescens was more resistant; the MIC90 being 4 mg/ml. Enoxacin also showed high activity against Campylobacter jejuni and Neisseria gonorrhoeae. Streptococci were comparatively resistant, 32 mg/l to 64 mg/l of the compound being required to inhibit 90% of strains.

Anti-Bacterial Agents↗
PubMed1985

Systemic mycosis in Scottish red deer (Cervus elaphus).

The pathological features of 10 cases of systemic infection of young red deer by fungi morphologically identified as phycomycetes are described. The most frequently affected organs were the kidneys, followed by liver and central nervous system. The fungi stimulated an acute pyogenic inflammatory reaction and a phagocytic giant cell response. Vasculitis with thrombosis and spread of fungi to the surrounding tissue was a common finding. Culture was attempted in 4 cases; one yielded Absidia, 2 Aspergillus and the other an unidentified fungal growth. Analysis of the histories suggests that, in nine of the ten cases, stressful husbandry may have been a predisposing factor.

Abomasum↗