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Biomedical subjects

M R Millar

Publications and source records attributed to M R Millar.

At least 109 records · Page 6Linked to original sources
PubMed1989

Direct isolation of coagulase-negative staphylococci from neonatal blood samples.

Coagulase-negative staphylococci (CNS) were isolated by direct inoculation of anticoagulated whole blood onto agar from 14 (41.2%) of 34 episodes (30 neonates) of suspected bacterial infection, associated with isolation of CNS from the same blood sample by broth-dilution blood cultures. The equivalent of more than 1,000 cfu ml-1 were isolated from four samples (four neonates); the range of counts was 1-103 cfu 25 microliters-1. There was a statistically significant association between isolation of CNS by direct agar inoculation and a raised C-reactive protein level and/or a positive nitroblue tetrazolium test and with the use of an intravascular catheter when compared to those episodes where CNS were isolated from broth blood cultures only. This simple procedure provides an estimate of the number of CNS in the blood of a neonate with suspected bacteraemia and may help to corroborate a diagnosis of CNS bacteraemia.

Coagulase↗
PubMed1989

Group C streptococci in human infection: a study of 308 isolates with clinical correlations.

A collection of 308 clinical isolates of beta-haemolytic Lancefield group C streptococci was assembled from laboratories in England, Nigeria and New Zealand. Of these, 276 isolates were Streptococcus equisimilis, 23 S. milleri and nine S. zooepidemicus. Isolates of S. equisimilis in the African collection, though few, gave higher rates of lactose and raffinose fermentation, aesculin hydrolysis and positive alpha-galactosidase reactions than those from elsewhere. Erythromycin resistance was found in 1.9% of the English isolates of S. equisimilis. Strains from superficial infections accounted for 88% of the collection and were most commonly isolated from the upper respiratory tract, skin or wounds. Amongst the 36 patients yielding isolates from deep sites S. equisimilis was found in septicaemia, cellulitis, abscess, peritonitis, septic arthritis, pneumonia, mycotic aneurysm and acute epiglottitis, S. milleri was found in abdominal abscesses, peritonitis, pleural empyema and osteomyelitis and S. zooepidemicus was found in septicaemia, pneumonia, meningitis and septic arthritis. Within the collection an unselected general catchment of 214 isolates of group C streptococci from the laboratories in Yorkshire showed the following species: from 199 superficial infections 94% S. equisimilis, 5% S. milleri and 1% S. zooepidemicus and 15 patients with deeper, more aggressive infections 67, 27 and 6.7% of these species respectively.

Cells, Cultured↗
PubMed1989

Tracheal tube biofilm as a source of bacterial colonization of the lung.

Biofilm formation in tracheal tubes, its bacterial content, and its interaction with ventilator gas flow were investigated. At least 50 mg (dry weight) of biofilm was found in 30 of 40 tracheal tubes used in intensive care patients for 2 h to 10 days. Electron microscopy showed bacteria in this layer, and quantitative studies showed that bacterial counts could reach up to 10(6)/cm of tube length. Bacteria were cultured from the patient side of 18 of 78 heat and moisture exchanger-microbiological filter units removed from ventilator circuits. Particles were shown to detach from tracheal tube luminal biofilm and were projected up to 45 cm from the tracheal tube tip. Following contamination of the tracheal tube biofilm with a patient's own gastrointestinal flora, entrainment of bacteria in the inspiratory gas flow provides a mechanism for initial and repeated lung colonization.

Bacteria↗
PubMed1988

Use of a continuous culture system for susceptibility testing of gram-negative bacterial isolates to piperacillin.

Fifteen (15.2%) of 99 Gram-negative bacteria isolated from patients during episodes of fever and neutropenia had minimum inhibitory concentrations ranging from less than 2 to 32 mg/l but were not fully sensitive to piperacillin by disc diffusion testing. These 15 isolates were further examined using a chemostat system, in which susceptible isolates were rapidly killed by piperacillin. Only three of the 15 isolates were susceptible to piperacillin when compared to sensitive control strains using the chemostat system. The results of this study suggest that an increase in the MIC to piperacillin is a less sensitive indicator of resistance to piperacillin amongst Gram-negative isolates than a reduction in the zone of inhibition in disc diffusion testing.

Bacterial Infections↗
PubMed1988

Enzymatic degradation of urinary indoxyl sulfate by Providencia stuartii and Klebsiella pneumoniae causes the purple urine bag syndrome.

The etiology of the purple urine bag syndrome (PUBS), in which the urinary catheter bag of some elderly patients develops intense purple coloration, was studied. The purple was found to be a mixture of indirubin dissolved in the plastic and indigo on its surface. Six patients with PUBS were studied, and Providencia stuartii was isolated from the urine of five and Klebsiella pneumoniae was isolated from the urine of one. These strains produced indigo in 7.9 mM indoxyl sulfate-containing agar. One hundred and fifty isolates of 41 species of bacteria were tested for their ability to produce indigo on agar containing indoxyl sulfate, but only 17 of 27 strains of P. stuartii, a single strain of Klebsiella pneumoniae, and Enterobacter agglomerans were positive. All of the indigo-producing bacteria had an indoxyl phosphatase with a pI of 6.4. This enzyme also possessed indoxyl sulfatase activity and was not present in strains that were unable to produce indigo from indoxyl sulfate. We conclude that PUBS results from the decomposition of urinary indoxyl sulfate to indigo and indirubin by bacteria (notably P. stuartii). As elderly catheterized patients often have high urinary indoxyl sulfate levels and colonization of their urinary tract with P. stuartii, the condition is most commonly seen in them.

Bacteriuria↗
PubMed1988

Isoelectric focusing of ureases from Campylobacter pylori and related organisms.

Agarose gel isoelectric focusing was used to determine the isoelectric points of ureases from strains of gastric campylobacterlike organisms isolated from ferrets (pI 5.4), baboons (pI 5.7), and pigs (pI 5.9) and from isolates of Campylobacter pylori in humans (pI 5.9). This technique may help differentiate these closely related bacteria.

Campylobacter↗
PubMed1988

Comparison of five tests used in diagnosis of neonatal bacteraemia.

The neutrophil count, immature:total neutrophil ratio, C reactive protein assay, nitroblue tetrazolium test and an acridine orange leucocyte cytospin test were evaluated for the diagnosis of neonatal bacteraemia. The acridine orange leucocyte cytospin test gave the highest specificity and positive predictive accuracy, but was less sensitive than the neutrophil count, C reactive protein assay or nitroblue tetrazolium test, particularly for the diagnosis of bacteraemia caused by coagulase negative staphylococci. No single test gave the sensitivity, specificity, and positive predictive accuracy of the combined results of the acridine orange leucocyte cytospin, C reactive protein, and nitroblue tetrazolium tests.

Acridine Orange↗
PubMed1987

'Methicillin-resistant' Staphylococcus aureus in a regional neonatology unit.

In December 1985 a neonate was transferred to a Yorkshire Regional Neonatology Unit (RNU) from a neighbouring hospital and was subsequently found to be colonized with a 'methicillin-resistant' strain of Staphylococcus aureus (MRSA). Spread of the MRSA was controlled by routine cross-infection methods. The RNU was not closed to new admissions, the economic cost of control measures was small and no neonatal death was attributable to MRSA infection. Eradication of the MRSA from the RNU was associated with a decline in frequency of coagulase-negative staphylococci (CNS) from blood cultures, but the overall frequency of positive blood cultures did not decline and there was a rise in frequency of isolation of Gram-negative bacterial species. The decline in frequency of CNS isolates from blood cultures may have resulted from a reduction in the level of cross-colonization of neonates with antibiotic-resistant CNS strains and also increased usage of erythromycin and vancomycin.

Cross Infection↗
PubMed1987

Pattern of antibiotic and heavy-metal ion resistance in recent hospital isolates of Staphylococcus aureus.

Two hundred and one strains of Staphylococcus aureus isolated from in-patients and out-patients were examined for sensitivity to antibiotics, heavy-metal ions and ethidium bromide and for phage-typing pattern. Heavy-metal ion resistance was less frequent than reported in previous studies and was as frequent in penicillinase non-producing as producing strains. 'Methicillin-resistant' strains were resistance to ethidium bromide and mercury. Resistance to heavy-metal ions, including cadmium, may be becoming less common amongst clinical isolates of S. aureus.

Anti-Bacterial Agents↗
PubMed1987

beta-Lactamase production by intestinal spirochaetes.

beta-Lactamase production was demonstrated in four of nineteen strains of intestinal spirochaetes isolated from human subjects. The enzyme was preferentially active against penicillins and was inhibited by clavulanic acid; it was membrane bound and non-inducible. No plasmids were detected in the intestinal spirochaetes and the beta-lactamase-production characteristic was not transferable to non-producing strains.

Humans↗