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T F O'Brien

Publications and source records attributed to T F O'Brien.

At least 55 records · Page 3Linked to original sources
PubMed1986

Genetic and physical characterization of IncM plasmid pBWH1 and its variance among natural isolates.

We present a genetic and physical characterization of the IncM plasmid pBWH1. A physical map was constructed for the enzymes EcoRI, BamHI, SalI, BglII, HindIII, MstII, and XhoI. A series of deletions and a series of subclones of pBWH1 were constructed and used to determine the locations on this map of the transfer region; the replication region; and the genes determining resistance to beta-lactams, chloramphenicol, the sulfonamides, and gentamicin. We compared 51 different isolates, including isolates which had lost individual antibiotic resistances or the transfer phenotype, and showed that variations occurred in all regions of the plasmid genome. Frequently, correlations could be made between phenotypic variation and variation of the EcoRI fragments which contained the gene determining that phenotype.

Chromosome Mapping↗
PubMed1985

Intercontinental spread of a new antibiotic resistance gene on an epidemic plasmid.

Bacteria of different genera isolated at nine medical centers in different parts of the United States and at one center in Venezuela during the first decade of gentamicin usage carried the gentamicin resistance gene 2"-aminoglycoside nucleotidyltransferase on the same transferable plasmid. Such widespread dissemination of a newly observed resistance gene on one plasmid suggests that a new resistance gene may emerge once on a single plasmid, which then carries it to other centers and other plasmids. The resistance gene might, therefore, be contained if detected early.

Bacteria↗
PubMed1985

Revisiting the Holy Cross football team hepatitis outbreak (1969) by serological analysis.

Clinical and biochemical data collected during the Holy Cross College football team hepatitis A outbreak in 1969 suggested that 32 team members had icteric hepatitis, 58 had anicteric illness, and only seven were not infected. Using a currently available radioimmunoassay, we tested stored serum samples obtained during the outbreak for IgM antibody to hepatitis A virus (IgM anti-HAV). Only individuals with icteric hepatitis were found to have IgM anti-HAV in serum; those with presumed anicteric illness were shown not to be infected with hepatitis A virus. The attack rate was thus only 34%, not 93% as originally reported, and the incidence of icteric illness in those infected was 100%, not 33%. This serological analysis of a classic outbreak of hepatitis A illustrates the utility and importance of IgM anti-HAV testing in seroepidemiologic investigations of hepatitis outbreaks.

Alanine Transaminase↗
PubMed1985

Resistance to antibiotics in clinical isolates of Klebsiella pneumoniae.

The antibiotic resistance of Klebsiella pneumoniae isolates from 12 medical centers worldwide, over a 1- to 6-year period, were tested. Clinical isolates of K. pneumoniae were resistant to ampicillin and carbenicillin. Resistance to other antibiotics was less frequent with isolates of K. pneumoniae from 5 of 6 US centers than with those from 6 centers outside the US. In nearly all of the centers, resistance to sulfamethoxazole-trimethoprim, gentamicin, tobramycin, or chloramphenicol was more frequent in isolates of K. pneumoniae than in those of Escherichia coli, while the reverse was true for resistance to tetracycline. Resistance to multiple antibiotics declined gradually in isolates of K. pneumoniae at one center, but rose abruptly again with dissemination of a new plasmid.

Ampicillin↗
PubMed1985

Trimethoprim resistance in multiple genera of Enterobacteriaceae at a U.S. hospital: spread of the type II dihydrofolate reductase gene by a single plasmid.

The percentage of clinical isolates of several species of Enterobacteriaceae, particularly Escherichia coli and Klebsiella pneumoniae, resistant to trimethoprim (TMPR) has increased gradually at the Brigham and Women's Hospital (Boston) in recent years. Thirty-seven of 42 TMPR isolates from six species of gram-negative bacilli conjugally transferred TMP resistance to K12 E. coli. beta-Lactam resistance cotransferred from 21 of the 37 donors, and sulfamethoxazole (SMZ) resistance cotransferred from five of the 37 donors. Plasmids that encoded TMP resistance either alone or with SMZ resistance had a molecular size of approximately 52.5 kilobases, with identical restriction endonuclease-generated "fingerprints." Plasmids encoding beta-lactam-mediated resistance (beta R) were approximately four kilobases larger and had fragment patterns that were identical for all of the TMPR/beta R plasmids tested and had many restriction endonuclease-generated bands in common with TMPR plasmids. Radiolabeled dihydrofolate reductase (DHFR) probes identified the type II DHFR as the determinant of TMP resistance. In contrast with reports from Europe, TMP resistance in multiple species of Enterobacteriaceae was found to be spread in one hospital by a single, stable conjugative plasmid that has a wide host range and encodes the type II DHFR gene.

Conjugation, Genetic↗
PubMed1984

Urinary tract infections in an American rehabilitation hospital.

In order to gain a better understanding of urinary tract infection in a rehabilitation hospital, the hospital courses of 119 consecutively admitted patients were studied. Bacteriuria on admission and subsequent incidence of urinary tract infection occurred chiefly among those patients with diagnoses involving peripheral vascular disease and low level of function (Barthel Index) on admission assessment. Females and diabetics among that group were particularly at risk. It was concluded that by using admission screening for detection of bacteriuria and level of function, the members of the high risk group could be predicted, and early urology consultation for bladder training programmes could be focused on those patients who might derive the most benefit.

Aged↗
PubMed1984

Diagnostic microbiology laboratory susceptibility test results discriminate distinctive antibiotic resistance plasmids.

The sizes of the zones of inhibition around routinely tested antibiotic disks classified gentamicin-resistant isolates of Klebsiella pneumoniae from one hospital into four major antibiotype classes. From each isolate of the prevalent class (A1), two plasmids could be transferred conjugally. One carried genes for resistance to tetracycline, sulfonamides, and chloramphenicol, and for the SHV beta lactamase. The other carried genes for two aminoglycoside-inactivating enzymes, APH (3')-I and AAC (3)-III, for the TEM 1 beta lactamase, and for resistance to sulfonamides. Transconjugants of either plasmid from any A1 isolate yielded the same DNA fragments after restriction endonuclease digestion, but the two plasmids had no fragments in common. Fragments or genes from either plasmid were variously combined or lacking in plasmids from variant isolates (A2, A3, and A4). Plasmids transferable from isolates of classes B and C shared no common DNA restriction fragments with each other or with either plasmid from Class A. Fragments and genes of the plasmids from C isolates, however, were identical with those of a plasmid endemic in a nearby hospital. Routine monitoring by diagnostic microbiology laboratories of distinctive antibiotypes and of the plasmids that produce them would aid infection control and antibiotic usage policy.

Anti-Bacterial Agents↗
PubMed1984

Infection control surveillance in a rehabilitation hospital.

Infection control surveillance in a rehabitation setting is essential to quality assurance because of the high number of infection risk factors found in this patient population. These factors include longer length of stay, high incidence of urinary tract instrumentation, and high incidence of skin lesions, including decubital and stump wounds. A surveillance process is described which offers timely access to each infected patient's diagnosis, treatment, and follow-up, and results in simplified hospital-wide antibiotic monitoring. Quality assurance problems identified through this surveillance plan involved specimen collecting and reporting errors, nursing-procedure inadequacies, and organism misidentification. These and other examples illustrate the distinctive role an infection control program can play in quality monitoring and problem solving in a rehabilitation hospital.

Cross Infection↗
PubMed1983

Starch blockers.

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Adult↗
PubMed1983

New concepts in medical bacteriology.

Traditional tests employed in a clinical microbiology laboratory for speciation of bacteria rely upon the presence of one or more gene products (biochemical profile) from a population of bacterial cells. These traits have been stable over a relatively long period of time, and the techniques have served us well. Current technology allows for modification and potential improvement of this system. By chemically separating DNA strands and employing recombinant DNA techniques, direct identification of bacteria becomes possible. These methods can be adapted directly to the clinical setting. In addition, specific gene products yield clinical disease; monoclonal antibodies directed against these products may speciate a bacterium indirectly through a unique gene product. Specific gene products also provide markers for epidemiologic investigation. All these technologies should find frequent clinical application in the next several years. The discoveries a century ago that germs cause infection and that different germs cause different infections prompted the development of a system of taxonomy for pathogenic microbes. It then became apparent that the identity of the germ infecting a patient could tell us more about his or her diagnosis and prognosis than could all of the clinical skills accumulated up to that time.

Anti-Bacterial Agents↗
PubMed1982

Molecular epidemiology of antibiotic resistance in salmonella from animals and human beings in the United States.

We collected serotyped isolates of salmonella from reference laboratories in the United States, tested their susceptibility to antibiotics, and extracted plasmids from isolates that were resistant to a different combination of antibiotics from each of three serotypes. Restriction-endonuclease digestion showed that within each of the three groups, plasmid molecules from animal and human isolates were often identical or nearly identical. One serotype-plasmid combination appeared to be endemic in cattle in 20 states and infected 26 persons in two states. The human cases, which were not recognizably related except for their common plasmids, appeared to be clustered in time but geographically dispersed, like cases in previous outbreaks spread by food products. These findings suggest that resistance plasmids may be extensively shared between animal and human bacteria, and that spread of multiresistant strains of salmonella among animals and human beings, as observed in Britain, may have been undetected in the United States for lack of comparable surveillance.

Animals↗
PubMed1981

Moxalactam therapy of infections caused by cephalothin-resistant bacteria: influence of serum inhibitory activity on clinical response and acquisition of antibiotic resistance during therapy.

Thirty patients infected predominantly by Serratia marcescens and Pseudomonas aeruginosa were treated in an open trial with moxalactam, a broad-spectrum beta-lactam antibiotic. Twenty-three (76%) had a satisfactory microbiological or clinical response. Among 25 patients for whom serum inhibitory concentrations were measured, those with favorable microbiological responses had significantly higher values than those with poor responses (reciprocal geometric mean concentrations, 49 versus 4.9; P less than 0.01). A serum inhibitory concentration of greater than 1:8 correlated significantly with a favorable outcome (17 of 18 versus 2 of 7 responses; P less than 0.01). Although the overall clinical efficacy of moxalactam was good, resistant organisms of species identical to those of the original infecting isolates were recovered during therapy in seven cases, including five caused by Pseudomonas organisms and two caused by Serratia organisms.

Adult↗
PubMed1980

Dissemination of an antibiotic resistance plasmid in hospital patient flora.

The 2'' aminoglycoside nucleotidyltransferase, AAD (2''), which adenylates gentamicin, tobramycin, and kanamycin, became prevalent over several months in multiple strains and species of Enterobacteriaceae isolated at one hospital. Eight plasmids with the gene for this enzyme purified from different strains and species isolated at different times had similar EcoRI digestion fragments, indicating that the gene had disseminated on one plasmid without transposition. This 56.5-megadalton plasmid of incompatibility group M, which also carried three other resistance genes, spread, at first, largely in one strain of Klebsiella pneumoniae, which later disappeared. It transferred to some strains which tended not to colonize other patients and later circulated predominantly in Serratia marcescens. Computer surveillance of routine hospital laboratory results was able to detect and trace the gene and the plasmid and measure their effect on resistance prevalence.

Aminoglycosides↗
PubMed1978

International comparison of prevalence of resistance to antibiotics.

Prevalence of bacterial resistance to antibiotics was found to be substantially different in two separate regions of the world. The average percent resistant to individual antibiotics was nearly three times greater, and the percent of isolates resistant to six or more antibiotics 14 times greater among isolates at the Hôpital St Joseph in Paris than among those at the Peter Bent Brigham Hospital in Boston or at any of six US hospitals. Differences were not due to culture sampling or susceptibility testing methods used in the hospitals. Differences were nearly as great between isolates from patients recently admitted to the two hospitals, suggesting differences in the bacterial flora of their communities. Similar systematic comparisons of resistance prevalence in different parts of the world might help to define optimal antibiotic usage practices.

Anti-Bacterial Agents↗