Contamination of specimen container surfaces during sputum collection.

Sputum specimens from culture-positive tuberculosis patients were examined for the presence of Myobacterium tuberculosis on container surfaces. Although specimens were in transit for several days, M tuberculosis was isolated from 18 (6.5%) of 279 containers examined. Sputum specimens from local patients were examined for evidence of upper respiratory bacterial flora on the outside of containers as an indicator of contamination with sputum. Of 300 containers examined, 41 (14%) were contaminated. A technique for disinfecting specimen containers from tuberculosis patients has been evaluated and recommendations are made for handling sputum containers.

Urinary infection with coagulase-negative staphylococci in a teaching hospital.

In the eight-month period of study of all urine samples processed in our routine laboratory, only 85 out of 12 152 specimens yielded a bacteriologically significant growth of either Staphylococcus epidermidis or micrococci. Their growth on MacConkey medium was strictly comparable to that on cysteine lactose electrolyte-deficient (CLED) media. Most micrococci isolated were from urine samples of non hospitalised women patients, were resistant to a novobiocin (5 micrograms) disc, and belonged to Baird Parker type 3. Staph. epidermidis came mainly from postoperative surgical in-patients. Their antibiotic sensitivity patterns are variable whereas micrococci are fully sensitive to all urinary antibiotics. We agree that the use of a novobiocin (5 micrograms) disc for provisional identification of micrococci and Staph. epidermidis is simple and practical for a busy routine diagnostic laboratory. The use of more extensive systems to biotype these organisms in a routine laboratory is not practical and not relevant to patient management.

Rapid gentamicin assay by enzymatic adenylylation.

A method is described for the assay of gentamicin using the enzyme gentamicin adenylyltransferase derived from an R-factor-carrying strain of Escherichia coli. The reaction involves adenylylation of the gentamicin with ((14)C)-ATP to form a radioactively labelled product. The technique is compared with the plate diffusion and the urease methods. The adenylylation technique gives results comparable to the plate diffusion assay and is more accurate than the urease method.

Extrapulmonary tuberculosis: a potential source of laboratory-acquired infection.

A three-year retrospective study has demonstrated the effect of extrapulmonary tuberculosis on safety within a routine bacteriology laboratory. The investigation showed that, from 112 patients, 162 specimens considered to present a risk to laboratory staff were processed outside of the B1 protective area. However, it was estimated that only 51 of those specimens were heavily positive. Of these 57% were sputum 30% pus, and 10% urine. Specimens of pus and urine account for 50% of specimens received for non-tuberculosis investigations, and it would be impossible to process all specimens that might present a risk in B1 accommodation and still maintain a high degree of safety. It is recommended that request forms which accompany specimens should clearly indicate potential high-risk specimens.

Significance of the isolation of Clostridium welchii from routine blood cultures.

Clostridium welchii has been demonstrated in approximately 20% of contact plates taken from the antecubital fossa of 185 inpatients and outpatients and healthy staff. The highest incidence was in a group of 40 very ill patients. The isolation of the organism from blood cultures is not always of clinical significance. Skin preparation as at present practised is often inadequate to remove the spores when contamination is relatively heavy, for example, in bedridden patients.

Use of the Phoenix system for bacteriology.

A dedicated microbiology data processing system with remote batched job entry to an obsolete computer, has been superseded by the inclusion of bacteriology in an on-line interactive clinical pathology system which had previously incorporated chemical pathology and haematology. The original Phoenix system has been adapted to allow for the entry of bacteriology data using mnemonic codes and to deal with the problems caused by the longer processing time of bacteriology specimens. Particular advantages of the new system include the immediate linkage of all specimens for each patient and an easy recall and display of results in the laboratories and on the wards.

A computer-assisted bacteriology reporting and information system.

A computer system for reporting and recording all specimens processed by the routine bacteriology laboratory at the Royal Postgraduate Medical School is described. Features of interest are the method of input using a mixture of 3-character alphanumeric codes and numbers, cumulative reporting to the wards, and selective listing of relevant previous results for the patient, which is available to technical and supervisory staff during processing of the specimen. The relative value to the wards and the laboratory of each type of information transfer has been assessed. Overall the use of a computer has resulted in higher quality bench work and more accurate reporting. It seems little more expensive than a previous manual system, although it has transferred work from the technical to the clerical staff.

The skin as the source of Acinetobacter and Moraxella species occurring in blood cultures.

A study was made of the flora of the skin in hospital inpatients and healthy people to demonstrate the presence of non-fermenting Gram-negative rods of the Acinetobacter and Moraxella group. These organisms were found to be present on the skin of 34.3% of inpatients and occurred even more commonly in those patients with kidney disease. It was also present on the skin of 20% of a group of healthy members of staff. This rather high rate of skin carriage is thought to account for the not infrequent occurrence of this organism in blood cultures.

A comparison of media used in vitro to isolate non-sporing Gram-negative anaerobes from blood.

Five anaerobic media were compared in a model blood culture system for their ability to recover small inocula of Gram-negative non-sporing anaerobes. Dehydrated cooked meat medium was the least effective; USP thioglycollate medium was the most effective isolation medium and is recommended for routine use. Freshly prepared cooked meat medium has the advantage of allowing prolonged survival of strains.

Trimethoprim: laboratory and clinical studies.

Trimethoprim is a synthetic compound which arrests the step in bacterial purine synthesis immediately succeeding that interfered with by sulphonamides. Acting alone it inhibits the growth of a wide range of bacteria in generally much lower concentrations than sulphonamides. Its action with a sulphonamide is strongly synergic and bactericidal.Studies are described of suitable cultural conditions, methods of testing sensitivity, and acquired resistance. Some clinical results of its use are reported in respiratory tract infections, Gram-negative septicaemia, and urinary tract infections, and further therapeutic possibilities are discussed.

Oral ketoconazole and amphotericin B for the prevention of yeast colonization in patients with acute leukaemia.

Forty-eight neutropenic patients with acute leukaemia were randomly allocated to receive, as antifungal prophylaxis, either ketoconazole, 400 mg once daily (K), or amphotericin B tablets and lozenges (A), or both ketoconazole and amphotericin B together (K + A). Antifungal prophylaxis was considered to have failed if (1) there was evidence of increasing colonization of the oropharynx or faeces with Candida spp. or other yeasts, or (2) if systemic antifungal therapy was begun empirically. Prophylaxis failed in nine of 17 patients given K, in four of 19 given A, and in four of 12 given K + A. The differences between the three regimens were not statistically significant, neither was there any significant difference in the mean duration of neutropenia before prophylaxis failed. The absorption of ketoconazole was impaired when patients were neutropenic. We conclude that ketoconazole was neither more nor less effective than amphotericin B in the prevention of yeast colonization in neutropenic patients.

Ceftazidime as first-line therapy for fever in acute leukaemia.

Fifty patients with acute non-lymphocytic leukaemia were treated by random allocation with either ceftazidime alone or a combination of piperacillin, netilmicin and cefotaxime for 65 febrile neutropenic episodes. Nineteen of 33 patient episodes (58%) responded to ceftazidime alone compared with 21 of 32 episodes (66%) treated with the combination. There was one infective death in a patient given the combination; rates of documented superinfection were low. The treatment groups appeared identical in terms of patient demography, underlying disease and other risk factors, though patients with a clinical site of infection responded more slowly than those without. Bacteraemia per se did not appear to influence outcome. Bactericidal serum concentrations greater than or equal to 8 X the minimum bactericidal concentration were predictive of a rapid response (within 4 days) to antibiotics. Furthermore, serum from patients treated with ceftazidime maintained adequate cidal activity against Pseudomonas aeruginosa for longer than that obtained from patients treated with the three-drug combination. Ceftazidime was shown to be a safe and effective alternative to the three-drug combination for the initial management of febrile neutropenic episodes in leukaemic patients.

A comparison of two prophylactic antibiotic regimes for open-heart surgery.

Two groups of patients undergoing open-heart surgery were given prophylactic courses of antibiotic lasting five days. One group (61 patients) received a cephalosporin and the second (57 patients) received a combination of penicillin, flucloxacillin and streptomycin. The overall major infection rate was low (3--4%), particularly so in the cephalosporin group (1.6%). There was no increased nephrotoxic effectt of the cephalosporin, and any nephrotoxic effect that was present was temporary and clinically unimportant. The major infecting organism in both groups was Staphylococcus albus (Staph. epidermidis). The efficiency, therefore, of any prophylactic regime which omits gentamicin, to which Staph. albus in usually sensitive, remains in doubt.

Comparative in vitro activity of daptomycin (LY146032) and vancomycin against gram-positive cocci determined using a pharmacokinetic model.

The activity of daptomycin (LY146032) and vancomycin was compared for methicillin-sensitive and methicillin-resistant (MRSA) strains of Staphylococcus aureus and for Enterococcus faecalis, using a semi-automated model that allows examination of time-kill curves with diminishing drug concentrations, thus reflecting in vivo pharmacokinetics. Exposure to daptomycin resulted in rapid killing of all strains of staphylococci and Enterococcus faecalis tested. Methicillin-sensitive staphylococcal strains appeared marginally more susceptible than MRSA. By contrast, the activity of vancomycin appeared much reduced. For all strains, greater than 90% kill was not observed within 24 h. Enterococcus faecalis was uniformly less susceptible to both agents than were staphylococci. The results suggest that despite similar values for MICs, the activity of daptomycin against strains of Staphylococcus aureus and Enterococcus faecalis is comparable to and may exceed that of vancomycin, although the significance of such differences is uncertain.

Carbenicillin resistance in Pseudomonas aeruginosa from clinical material.

Strains of Pseudomonas aeruginosa resistant to 256 mug. per ml. or more of carbenicillin (Pyopen) were isolated from 17 patients over a period of three months. The infections were not solely due to cross-infection. Low dosage and attempted eradication of the organism from inaccessible sites, such as the bronchi or skin surfaces, by using systemic treatment are two possible causes. Restraint in treating infections of doubtful importance and the use of local applications to appropriate sites with or without systemic treatment is suggested.

Secondary septicaemia from intravenous cannulae.

Within a period of only seven months three patients in one hospital under treatment with antibiotics by intravenous infusion developed secondary bloodstream infection originating from the site of insertion of the cannula. Two of these infections were fatal. Precautions suggested include strict asepsis, the skin being sterilized with iodine in spirit solution; antibiotic spray; and changing the cannula site.