Biomedical subjects

J L Blakey

Publications and source records attributed to J L Blakey.

4 recordsLinked to original sources

PubMed1989

Infectious diarrhea in children undergoing bone-marrow transplantation.

Fecal flora of 12 children undergoing bone-marrow transplantation was monitored prospectively using comprehensive microbiological techniques. Diarrhea developed at least once in ten of the 12 children (83%), and a total of 24 episodes were recorded. Recognised gut pathogens were isolated from 11/21 (52%) diarrheal episodes where fecal specimens were obtained. Enteric pathogens identified included viral pathogens in 19% (rotaviruses, 'enteric' adenoviruses), parasites in 19% (cryptosporidium, Giardia lamblia) and cytotoxic C. difficile (14%). Excretion of clostridial species (including cytotoxin negative C. difficile, C. innocuum) occurred in 90% of diarrheal episodes when no enteric pathogen was identified. These results suggest that infection is often responsible for diarrhea associated with bone-marrow transplantation. Prophylaxis against enteric infection might reduce the morbidity and mortality associated with severe diarrhea in bone-marrow transplanted children.

Adolescent↗

PubMed1985

Enteric colonization in sporadic neonatal necrotizing enterocolitis.

Microflora of the gut was studied close to the onset of sporadic necrotizing enterocolitis (NEC) in neonates. Enteric flora in 25 babies with NEC differed from that in 23 matched controls. Bacteroides spp and lactobacilli were less common in babies with NEC compared with controls: 32 versus 61% (p = 0.03) and 12 versus 48% (p = 0.006), respectively. Clostridium perfringens was isolated from 40% of babies with NEC compared with 13% of controls (p = 0.03). It was present in 33% of babies with NEC aged less than 14 days but was not detected in control babies of the same age. The incidences of C. butyricum and C. difficile were similar in patients and controls. Colonization with C. perfringens in the absence of a protective barrier flora may be crucial in the pathogenesis of severe sudden onset NEC. Two potentially valuable marker factors to predict onset of this form of sporadic NEC are the use of fecal smears and estimation of fecal tryptic activity.

Bacteroides↗

PubMed1982

Development of gut colonisation in pre-term neonates.

Twenty-eight pre-term babies of low birth weight were monitored for developing microflora in throat, stomach and faeces during the first 3 weeks of life. The flora at all levels of the gastrointestinal tract differed from that of healthy breast-fed and artificially fed full-term babies. Colonisation of throat and stomach was delayed beyond 4 days of life in 87% and 60% of babies respectively. Only 10% of babies had "normal" oral flora throughout the period of study. Flora of the stomach was sparse, and resembled faecal flora. Faecal flora was established more rapidly than throat or stomach flora, and 70% of babies were colonised during the first 4 days of life. Initially Bacteroides spp. were predominant (57% babies), but Escherichia coli and other aerobic gram-negative bacilli gradually increased in frequency. Colonisation by gram-positive bacteria was slow. Clostridium spp. were present in only 10% of babies during the first 4 days of life. Most strains were transient. Colonisation with C. butyricum (30%), C. perfringens (35%) and C. difficile (25%) was maximum after the first 2 weeks of life. Lactic-acid-producing bacteria usually appeared late in the third week of life. Parenteral feeding immediately after birth was associated with delayed colonisation by a restricted number of species. Parenteral antibiotics (penicillin or gentamicin or both) restricted colonisation with normal oral flora, the lactic-acid-producing bacteria and penicillin-sensitive clostridia, but had little effect on E. coli even when the colonising strain was sensitive to the aminoglycoside in the regimen. Systemic spread of bacteria via the blood stream was not detected in any babies. The pattern of colonisation of the enteric tract in pre-term infants in the special-care nursery studied, differs from that of healthy full-term babies; this merits consideration when the results of bacteriological tests of this vulnerable group of infants are being interpreted.

Anti-Bacterial Agents↗

PubMed1975

A review of bacteria in L-phase and their possible clinical significance.

L-phase bacteria are bacterial variants produced by adverse conditions in the environment. Although variant growth may be perpetuated for generations, the changes are not of genetic origin, but due solely to the environment which causes damage to the bacterial cell wall. Since the structure of Gram-positive and Gram-negative cell walls is fundamentally different, the degraded variant which will occur in each case will also be different. Such variants are seldom detected in routine diagnostic laboratories because they will not grow on normal media, as their optimal conditions of growth are changed. L-phase variants bear a strong resemblance to the mycoplasmas; both are resistant to penicillin, both lack characteristic bacterial cell wall constituents, and their colonial and cellular morphology are similar. Since the conditions for mycoplasma cultivation are, at this time, more clearly understood, they provide useful models for handling fragile L-phase organisms. L-phase bacteria may be readily produced in vitro by the action of penicillin, and it is theoretically possible for conversion to occur in vivo just as readily during phagocytosis, by the action of bacteriophage, antibiotic therapy, and other defence mechanisms of the host. In the clinical field, the most difficult problem is the assessment of the significance of the isolation of L-phase bacteria in the individual case because they have not been observed with certainty in the pathological process. It is probable that such organisms may be clinically significant in cases of chronic and recurrent infection, since these bacteria will survive the defence mechanisms of the host which are largely directed at the cell wall.

Anti-Bacterial Agents↗