Search PubMed⌕ Search

Biomedical subjects

R C Moellering

Publications and source records attributed to R C Moellering.

At least 199 records · Page 11Linked to original sources
PubMed1976

Effects of penicillin and lysozyme on the immunofluorescent and precipitin reactivity of group D streptococci.

Damage to the cell wall by growth in the presence of penicillin or by treatment with lysozyme enhanced the immunofluorescent (fluorescent antibody, FA) reactivity to group D streptococci. The optimum concentration and time of treatment with lysozyme varied inversely with the initial FA reactivity of the strain. Speciation of the organisms by a series of biochemical and physiologic tests suggested that the differences in initial FA reactivity were species-related. Thus, S. faecalis strains were the most FA-reactive and most sensitive to lysozyme. S. faecium strains were less FA-reactive and lysozyme-sensitive. S. bovis strains proved to be least FA-sensitive and were most resistant to lysozyme. Treatment with lysozyme was also effective in preparing extracts of group D antigen from all three species for Lancefield grouping by the precipitin test. The lysozyme extracts, moreover, produced much stronger reactions than those made from comparable volumes of cells by the methods of Lancefield or of Rantz and Randall.

Antibodies, Heterophile↗
PubMed1976

Clinical significance of Lancefield groups L-T streptococci isolated from blood and cerebrospinal fluid.

The aim of a study of all groups L-T streptococci isolated at the Massachusetts General Hospital during a 10-year period (1964-1974) was to ascertain the clinical significance of the less frequently occurring serological groups of streptococci. No organisms of groups P,R,S, or T were found during this time. The case records of 109 clinical isolates of alpha-reacting streptococci of Lancefield groups L,M,N, and O from blood and cerebrospinal fluid cultures were reviewed. There were six cases of endocarditis and one case of infected sternotomy uound with septicemia due to these streptococci. The two cases of endocarditis due to group O streptococci represent the first cases described with endocarditis caused by this group of organisms. Virtually all of the isolates of groups L,M,N, and O streptococci were susceptible to penicillin. Seventy-four percent of the isolates were judged not responsible for clinical disease. The importance of avoiding inappropriate therapy makes it necessary to realize that these organisms are potential "contaminants" of cultures of blood and cerebrospinal fluid.

Blood↗
PubMed1976

Emergence of gentamicin-resistant bacteria: experience with tobramycin therapy of infections due to gentamicin-resistant organisms.

A computerized system for testing and surveillance of bacterial susceptibility to antibiotics was used in monitoring the emergence of gentamicin-resistant strains of aerobic and facultative gram-negative bacilli at Massachusetts General Hospital since the release of gentamicin for clinical use in 1971. During the period studied, there was a significant increase in the prevalence of gentamicin-resistant bacteria, particularly among Pseudomonas, Acinetobacter (Herellea), and Proteus and, more recently, among Enterobacter and Klebsiella. Most gentamicin-resistant strains of Pseudomonas aeruginosa and Acinetobacter calcoaceticus var. anitratum (Herellea varginicola) retained susceptibility to tobramycin. Of the other gentamicin-resistant organisms, most were also resistant to tobramycin. Twelve patients with infections caused by gentamicin-resistant organisms were treated with tobramycin. All 12 patients were seriously ill, and all but one had failed to respond to previous therapy with gentamicin. Nine patients responded favorably to tobramycin, and six were cured. P. aeruginosa and A. calcoaceticus var. anitratum were most frequently the infecting organisms in these patients. Patients received tobramycin for three to 42 days; no significant drug-related toxicity was noted. These results emphasize the increasing clinical importance of gentamicin-resistant bacteria and suggest that tobramycin may be effective for treatment of some, but not all, infections caused by gentamicin-resistant bacteria.

Acinetobacter↗
PubMed1976

Gentamicin dosage in children with extensive burns.

During the treatment of Gram-negative bacillary infections in severely burned children, it was noted that administration of standard dosages of gentamicin commonly produced inadequately low serum concentrations of the antibiotic. Pharmakokinetic studies demonstrated that mean peak serum gentamicin levels were significantly lower in 18 burned children as compared with peak serum levels in five unburned children. Furthermore, inadequately low peak serum levels (less than 3.0 mug/ml) were observed in 15 of 18 burned children and in only one unburned child. Clearance studies in two children suggested that the increased requirement for gentamicin can result from either loss of the antibiotic across burn wounds or increased urinary excretion. These studies indicate that the therapy of severe infections in children with major burns often requires administration of gentamicin at higher doses and more frequent intervals than usually employed.

Adolescent↗
PubMed1975

Salmonella typhimurium resistant to silver nitrate, chloramphenicol, and ampicillin.

A strain of Salmonella typhimurium appeared sequentially in three patients in a burn unit, and epidemiological study suggested the occurrence of person-to-person spread. This organism was responsible for both colonisation and invasive infection in these patients whose burn surfaces were receiving topical treatment with 0.5% silver nitrate (AgNO3) solution. The antibiotic and metal ionsusceptibility pattern of this strain of S. typhimurium was unique and disturbing: resistant to silver nitrate, mercuric chloride, ampicillin, chloramphenicol, tetracycline, streptomycin, and sulphonamides. This pattern of multiple resistances could be transferred by invitro mating experiments to sensitive recipient strains of Escherichia coli and S. typhimurium. Further transfer of these resistances could be consumated between different strains of E. coli. A survey of other salmonella strains isolated from patients in this hospital without thermal burns did not reveal this pattern of resistance. Also, strains of S. typhimurium, isolated elsewhere and showing simultaneous resistance to both ampicillin and chloramphenicol, were not resistant to AgNO3 in vitro. The very real danger of this strain of S. typhimurium in burn units stems from its resistance to the two most effective antibiotics (ampicillin and chloramphenicol) available for systemic therapy; and this threat may be compounded through the selection effected by the widespread topical use of AgNO3 solutions and sulphonamide preparations on burned surfaces.

Adult↗
PubMed1975

Clinical, microbiologic and therapeutic aspects of purulent pericarditis.

Twenty-six patients with purulent pericarditis were seen at the Massachusetts General Hospital between 1960 and 1974. The diagnosis was made in 18 of them during life, but only 6 survived, with an over-all mortality rate of 77 per cent. In eight patients, purulent pericarditis developed in the early postoperative period after thoracic surgery. In seven, purulent pericarditis was the result of contiguous spread of infection from a pleural, mediastinal or pulmonary focus in nonsurgical patients. In five patients, it was the result of direct spread to the pericardium from an intracardiac infection. In the remaining six patients, purulent pericarditis developed as the result of a systemic bactermia. Immunosuppressive therapy, extensive thermal burns, lymphoproliferative disease and other systemic processes affecting host resistance were present in at least half the patients. Staphylococcus aureus was the etiologic agent in the largest number of patients (8 of 26 in this report). However, in contrast to previous studies, in a significant number of the patients (five), purulent pericarditis was the result of fungal infection (in three patients subjected to thoracic surgery and in two immunosuppressed patients). This report confirms that purulent pericarditis is an acute disease with a fulminant course. The diagnosis is easily missed since classic signs of pericarditis (including chest pain, friction rub and diagnostic electrocardiographic abnormalities) may be absent. The echocardiogram shows considerable promise in allowing earlier diagnosis of the pericardial effusion which accompanies purulent pericarditis. Optimal therapy consists of prolonged antibiotic therapy and aggressive drainage of the pericardium. In this series, there were 6 survivors among the 11 patients (55 per cent) who received appropriate therapy.

Acute Disease↗
PubMed1975

Evaluation of human oral organisms and pathogenic Streptococcus for production of IgA protease.

IgA protease is a proteolytic enzyme found in whole human saliva and in dental plaque that cleaves both secretory and myeloma IgA of human origin to yield intact Fabalpha and Fcalpha fragments. To determine which bacteria are capable of producing this enzyme, we have examined a variety of strains normally found in the human oral cavity and a number of streptococci of known Lancefield group serotype. Streptococci of groups A, B, C, D, F, G, H, M, and N, Streptococcus mutans, Streptococcus sanguis, Streptococcus mitior, Streptococcus salivarius, Streptococcus faecalis, Veillonella, Lactobacillus, Actinomyces, Propionibacterium, Bacteroides, and Fusobacterium were grown in liquid medium, and fluids were examined for IgA protease activity. Only S. sanguis and clinically isolated group H streptococci elaborated IgA protease under the culture conditions used. Negative strains could not be stimulated to produce the enzyme when cultured in the presence of secretory IgA. Among the natural oral bacteria, capacity to produce IgA protease is restricted to certain species of Streptococcus, notably those of the group H serotype. Since secretory immunity is mediated by the IgA class of antibody, the presence of this enzyme at mucosal surfaces could modify the secretory immune function.

Actinomyces↗
PubMed1975

Susceptibility of various serogroups of streptococci to clindamycin and lincomycin.

The minimal inhibitory concentration of lincomycin and clindamycin for a large number of strains from multiple serogroups of streptococci was determined. The median minimal inhibitory concentration for streptococci from groups A, B, C, F, G, H, L, and M and nongroupable organisms ranged from 0.02 to 0.39 mug of lincomycin per ml and from </=0.01 to 0.09 mug of clindamycin per ml. Among the group D strains, Streptococcus faecium and Streptococcus faecalis were resistant to lincomycin and clindamycin, whereas Streptococcus bovis and four American strains of Streptococcus durans resembled nongroup D isolates in their susceptibility to these agents. Occasional strains of nongroup D streptococci were highly resistant to lincomycin and clindamycin.

Clindamycin↗
PubMed1975

Studies of cephalothin: aminoglycoside synergism against enterococci.

Combinations of cephalothin and aminoglycoside antibiotics are not currently used in the therapy of serious enterococcal infections, because clinical trials of these combinations have been unsuccessful. Studies of 28 enterococci isolated from patients with enterococcal bacteremia suggested three possible mechanisms for this in vivo antibiotic failure: (i) a relatively high level of resistance to cephalothin among all enterococci and especially those characterized as Streptococcus faecium, (ii) a significant incidence of high-level resistance to the aminoglycosides among certain strains of enterococci, and (iii) a failure of synergism to occur when cephalothin concentrations fall below the minimal inhibitory concentration of the enterococcus, as occurs during the in vivo metabolism and excretion of this antibiotic when given in standard doses for endocarditis.

Aminoglycosides↗
PubMed1975

Identification of streptococci: serogrouping by immunofluorescence.

This paper deals with the fluorescent antibody (FA) method for identifying six commonly occuring and two rare groups of streptococci by using commercially prepared (Difco) conjugates. We have shown that group-specific FA produced frequent cross-reactions with heterologous groups of organisms. These reactions varied with different strains of the same serogroup. Nonetheless, there was distinct overall patterns in the intensity and appearance of the homologous and heterologous reactions. When monitored by the precipitin test with Rantz and Randall extracts, these patterns led to the correct identification of 90 to 100% of specimens of serogroup A, B, C, and G streptococci. Many members of groups D and F also showed distinctive reaction patterns. However, there was a significant number of strains of both groups D and F that either failed to strain or stained poorly with the homologous conjugate. As a result, the identification of these serogroups by FA was less reliable.

Cross Reactions↗
PubMed1975

Identification of streptococci: use of lysozyme and Streptomyces albus filtrate in the preparation of extracts for Lancefield grouping.

A combination of lysozyme and Streptomyces albus filtrate has been shown effective in extracting group-specific antigen for all commonly occurring serologically groupable streptococci. A prospective comparison of this method with that of Rantz and Randall (1955) for grouping 761 clinical isolates has confirmed its accuracy, which in our hands exceeded that of the latter more complicated method of serogrouping. Its rapidity and simplicity and the relatively low cost of the reagents involved make it practical for routine use in clinical bacteriology laboratories.

Cell-Free System↗
PubMed1975

Tuberculin and histoplasmin sensitivity in six solomon islands populations.

Skin testing with antigens from Histoplasma capsulatum, Mycobacterium tuberculosis (PPD-S), and atypical mycobacteria (PPD-B, PPD-G, PPD-Y, and PPD-platy) was carried out among six population groups in the Solomon Islands between 1968 and 1972. There was no positive reaction to histoplasmin among any of the groups, suggesting that histoplasmosis is not endemic in the Solomon Islands. There were significant numbers of tuberculin reactors among each group. Largest mean reactions to PPD-S were present among the Lau and Ulawa, in whom reactions to PPD-S were larger than those to any other antigen tested. Thus significant infection with M. tuberculosis appears to occur in these populations. This was corroborated by radiologic survey. Among the Lau, large reactions to PPD-G and PPD-Y were also elicited, raising the possibility of multiple infection. Among the Aita, Baegu, Nagovisi, and Ontong Java, PPD-G elicited the largest reactions. PPD-G produced the second largest reactions among the Lau and Ulawa. PPD-S elicited the largest or second largest reaction among 4 of the 6 groups. A notable exception was the Aita, in whom PPD-S elicited the smallest mean reaction. The Aita also had the lowest prevalence of radiologic findings consistent with tuberculosis. These observations suggest that M. tuberculosis has been introduced into the Solomon Islands from outside sources, a hypothesis which may explain the variability in prevalence of tuberculosis-like disease demonstrated by chest film among the six groups. Genetic differences may also play a role in this variability. The study also demonstrated a high prevalence of "baseline" sensitivity to the atypical mycobacteria among the Solomon Islanders. This sensitivity may confer some immunity to infection with M; tuberculosis, but this protection is far from complete.

Adolescent↗
PubMed1974

Susceptibility of clinical isolates of bacteria to cefoxitin and cephalothin.

The susceptibility of 4,929 unselected clinical isolates of bacteria to cefoxitin and cephalothin was determined by the single-disk method, using a computer-associated electronic zone analyzer to obtain, record, and process measurements of sizes of zones of inhibition. Both cefoxitin and cephalothin were effective against most gram-positive strains, including Staphylococcus aureus, S. epidermidis, micrococci, and all streptococci except enterococci. The three strains of Listeria monocytogenes tested were susceptible to cephalothin but resistant to cefoxitin. There was little difference between the cefoxitin and cephalothin susceptibility of Salmonellae, Citrobacter sp., Enterobacter sp., Proteus mirabilis, and Pseudomonas sp. Cefoxitin was more effective then cephalothin against Escherichia coli, Klebsiella sp., Serratia sp., indole-positive Proteus sp., Providence sp., Flavobacter sp., Herellea vaginicola, and Mima polymorpha. Cefoxitin also appeared to exhibit enhanced activity, as compared with cephalothin, against Bacteroides sp. Thus cefoxitin appears to have a very broad antibacterial spectrum which is greater than that of cephalothin, especially against gram-negative strains.

Anti-Bacterial Agents↗