Emergence of resistance to imipenem during therapy for Pseudomonas aeruginosa infections

We studied the mechanism of resistance to imipenem in three clinical isolates of Pseudomonas aeruginosa. Two of these isolates arose from imipenem-susceptible strains isolated during therapy with imipenem and were associated with treatment failure. One of these two strains had previously been broadly resistant to beta-lactams; the second acquired resistance to imipenem alone. One isolate of the third strain was resistant to imipenem but susceptible to other antipseudomonal beta-lactams. No isolate contained beta-lactamase activity capable of hydrolyzing imipenem at a detectable rate. Studies of the penicillin-binding proteins of all isolates revealed no differences in the number of proteins, molecular weight of, affinity for penicillin, or affinity for imipenem in any isolate. In each case the resistant isolate lacked one or more outer membrane proteins that were present in a susceptible isolate of the same strain. The observed alterations in outer membrane proteins may be associated with diminished permeability of the bacterial outer membrane to imipenem and may be the major factor responsible for resistance in these isolates.

Intracardiac infections due to coagulase-negative Staphylococcus associated with Hickman catheters

Three bone marrow transplant recipients experienced right-sided intracardiac infection due to coagulase-negative Staphylococcus infection associated with Hickman catheter use. In each case, multiple blood cultures yielded coagulase-negative Staphylococcus organisms, and echocardiography demonstrated mass lesions or vegetations in the right atrium. Two patients appeared to have infected intracardiac thrombi without definite valvular involvement, whereas one had both an atrial mass and a tricuspid valve vegetation. All patients were treated with catheter removal and 4 weeks of antibiotic therapy, and one patient required cardiac surgery after failure of antibiotic therapy and an apparent paradoxic embolus to the central nervous system. Intracardiac infection is a rare but potentially fatal complication of Hickman catheter use. Echocardiography may be useful in establishing the diagnosis in suspected cases.

DNA sequence of the region in the genome of herpes simplex virus type 1 containing the genes for DNA polymerase and the major DNA binding protein

In the long unique region of the genome of herpes simplex virus type 1 (HSV-1), the genes for DNA polymerase and the major DNA binding protein are arranged in a head to head manner, with an origin of DNA replication (termed OriL) located between them. This paper reports an 8400 base pair DNA sequence containing both genes and the origin, obtained mostly by M13/dideoxy analysis of plasmid cloned fragments. Amino acid sequences of the two proteins were deduced. Homologues of both genes were detected in the genome sequence of the distantly related Epstein-Barr virus (EBV). Arrangement of these HSV-1 and EBV genes differs in genome location and in relative orientation. A part of HSV-1 DNA polymerase was found to be similar to a sequence in adenovirus 2 DNA polymerase, but the significance of this is unclear. Since a DNA sequence in the locality of OriL deletes on plasmid cloning, this region was analysed using virus DNA. A palindrome with 72-residue arms was found, which shows great similarity to the better characterized origin, OriS.

Intracranial hematoma with subsequent brain abscess after carotid endarterectomy

A 62-year-old man developed an infected left carotid endarterectomy with false aneurysm formation and subsequent bacteremia after staged carotid endarterectomies. He was found to have a right frontal lobe hemorrhage that developed into a staphylococcal brain abscess. We postulate there was bacterial seeding of the hematoma resulting in brain abscess formation.

cDNA cloning of the nucleocapsid and nucleocapsid-associated protein genes of mumps virus

cDNA clones of the mumps virus N and P messenger RNAs were isolated from an infected cell cDNA library. The N and P clones selected the two predominant polyadenylated RNAs found in mumps virus-infected cells with mol. wt. of 0.69 X 10(6) and 0.51 X 10(6), respectively. In addition, clones of the P gene hybridized to and selected mRNAs of higher mol. wt. probably representing polycistronic transcripts of the mumps genome. Hybrid-select translation experiments confirmed the specificity of the clones as representing the nucleocapsid (N) and nucleocapsid-associated protein (P) genes.

Emergence of resistance to beta-lactam antibiotics in Pseudomonas aeruginosa during treatment with new beta-lactams

In 12 patients treated with cefsulodin for Pseudomonas aeruginosa infections, resistance to cefsulodin developed in the infecting strains of two patients who failed to improve clinically. In both cases, cross-resistance also appeared for a broad spectrum of new antipseudomonal beta-lactams, except imipenem. The resistant isolate from one patient had a new constitutive beta-lactamase for cephalothin which also had modest activity for cefsulodin, ceftazidime, and carbenicillin. Furthermore, all of the non-hydrolyzed beta-lactams appeared to be bound by a beta-lactamase in this isolate. The origin and role in beta-lactam resistance of the observed beta-lactamase activity are obscure. The resistant isolate from the other patient had no demonstrable beta-lactamase activity that could account for the beta-lactam resistance. In five patients treated with imipenem for P. aeruginosa infections, resistance to imipenem developed in the strains of two patients who failed to improve clinically. The strain from one patient was already resistant to all other antipseudomonal beta-lactams before imipenem therapy. The initial strain from the other patient was broadly susceptible, and it developed resistance only to imipenem. Prior to imipenem therapy, another patient, who had P. aeruginosa endocarditis, had isolates from blood with three different susceptibility patterns: susceptible to all antipseudomonal beta-lactams, resistant to all but imipenem, and resistant to imipenem alone. There was no demonstrable beta-lactamase activity to account for imipenem resistance in any of the isolates in these patients. None of the resistant P. aeruginosa isolates had a change in penicillin-binding proteins from those of their susceptible counterparts that might explain the development of resistance.(ABSTRACT TRUNCATED AT 250 WORDS)

The modification and evaluation of some cytochemical techniques for the enumeration of metabolically active heterotrophic bacteria in the aquatic environment

Variants of the tetrazolium-reduction, nalidixic acid-inhibition and fluorescein diacetate-hydrolysis techniques for enumeration of metabolically active bacteria were compared, using samples of planktonic, benthic, and epiphytic freshwater bacteria. Results obtained by these methods generally showed statistically significant differences. However, an INT reduction technique, without added substrate, and a slightly modified nalidixic acid procedure gave values which did not differ at the 5% level. The results indicated that from 10 to 40% of total bacteria in the samples examined were metabolically active. These values were up to two orders of magnitude higher than those obtained by conventional plate count techniques.

Outbreak of JK diphtheroid infections associated with environmental contamination

The group JK diphtheroid organism is a multiply resistant opportunistic pathogen which infects immunocompromised patients sporadically. We describe the first reported outbreak of JK diphtheroid infections, in which four cases of bacteremia and one Hickman catheter site infection occurred during 4 weeks on a hematology ward. On this ward, JK diphtheroid was recovered from 17 of 39 patients, 10 of 17 30-ft3 (0.840-m3) air samples, surfaces in 9 of 13 patient rooms, and hands of 4 of 22 personnel. Previously identified risk factors for JK diphtheroid sepsis (male gender, broad-spectrum antibiotic therapy, granulocytopenia, and prolonged hospital stay) were present in infected patients but did not distinguish them from patients who were only colonized. Emphasis on aseptic practices was associated with termination of the outbreak and negative hand cultures from personnel, despite continued patient colonization and environmental contamination.

Eosinophilic meningitis and ibuprofen therapy

We describe eosinophilic meningitis associated with ibuprofen therapy in a young woman who had no evidence of underlying illness. Discontinuation of ibuprofen was followed by prompt resolution of symptoms and disappearance of eosinophils from the CSF. Ibuprofen has been implicated previously in only five cases of aseptic meningitis--all in patients with an underlying autoimmune disease. No drug has been implicated previously as a cause of eosinophilic meningitis to our knowledge.

Measurement of 42K concentration in the mucosal portion of the intestine without tissue samples: an approach to the measurement of mucosal blood flow in the dog

1. The concentration of 42K within the jejunal mucosa was measured by intraluminal miniatrue Geiger-Müller tubes shieleded with platinum foil. 2. Isotope concentration measured by tissue assay of jejunal mucosa gave similar results to that obtained by the Geiger-Müller tubes. 3. Isotope measurement by shielded Geiger-Müller tubes obviates the need for tissue samples and permits repeat measurement in the same animal. This should find physiological application in measuring the mucosal portion of total intestinal blood flow by the indicator fractionation technique.

Intestinal blood flow in the dog measured by indicator fractionation without tissue samples

1. A modification of Sapirstein's indicator fractionation technique for measurement of intestinal blood flow has been studied and evaluated in the dog. 2. The concentration of 42K within the intestinal wall was measured simultaneously by a tissue assay procedure and by use of a miniature Geiger-Müller tube within the intestinal lumen. Both methods gave similar results under a wide variety of conditions. 3. Isotope measurement by the Geiger-Müller tube technique obviates the need for tissue samples to be taken and would permit repeat measurements of intestinal blood flow in the same animal.

Some observations on the epidemiology of toxoplasmosis in Canada

Between 1961 and 1974, 11934 samples of serum were tested by the Sabin-Feldman Dye test for the presence of antibodies to Toxoplasma gondii. Analysis of high-titred sera suggested that a 6-year cycle of high disease prevalence occurred across Canada. In addition, a decline in the percentage of positive reactions each year in the Fall. The suggestion that this decline was due to dry conditions during the summer months was supported by the observation that differences in the prevalence of toxoplasma infection in ten Canadian cities were related to their average summer rainfall. The significance of these observations in relation to the epidemiology of toxoplasmosis in this country is discussed. The influence of patient age on the prevalence of infection was also investigated; the results obtained suggested that at least 75% of infants with high antibody titres against T. gondii had obtained these antibodies by placental transfer from their mothers.

Estimation of maximal oxygen uptake in New Zealanders of three age groups

An assessment of cardiorespiratory fitness has been made in New Zealanders of both sexes, in three age groups. Three separate methods were used to predict maximal oxygen uptake (VO2 max) from observations during submaximal exercise on a bicycle ergometer. The nomogram of Astrand was inappropriate for the prediction of VO2 max in most groups: extrapolation of the submaximal data gave values essentially in agreement with those calculated from the formula of von Dobeln, Astrand, Bergstrom (1967). Mean VO2 max of each of the male groups was 40.31 ml/kg (adults); 43.54 ml/kg (university students) and 52.92 ml/kg (secondary school students). Corresponding values for females were 38.91 ml/kg, 46.64ml/kg and 42.87ml/kg. These values put young New Zealanders into a low fitness category compared with populations studied in Norway, Sweden, Japan, USA, Britain, Peru and Canada.