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PubMed1996

Summary of the International Consensus Symposium on Advances in the Diagnosis, Treatment and Prophylaxis and Cytomegalovirus Infection.

CMV infection and CMV disease can be difficult to differentiate and the diagnosis is usually based on a compatible clinical picture and the results of a diagnostic test for CMV. The only exception to this rule is in HIV-infected patients where fundoscopy is sufficient to diagnose CMV retinitis. Of the current diagnostic tests, qualitative and quantitative PCR, branched DNA and Hybrid Capture, are the most promising. The pp65 antigenemia assay has the disadvantage of being more labor-intensive than the DNA based tests. Preliminary data show that a positive qualitative PCR in a HIV-infected patient has a predictive value for the development of CMV retinitis. However, of the patients positive by qualitative PCR, those with high viral loads in quantitative PCR were at the greatest risk of CMV disease. This might make it possible to identify with great certainty the patients who will go on to develop CMV retinitis, thereby decreasing the number of patients eligible for preemptive or prophylactic therapy and increasing the cost-benefit of this therapeutic measure. Quantitative test might also be useful in monitoring response to therapy, but randomized trials comparing the test are needed. Prophylactic antiviral agents should not be used in seronegative transplant recipients receiving organs from seronegative donors. In high-risk transplant recipients, ganciclovir should be used. CMV vaccines are useful for the protection of babies from CMV seronegative mothers against congenital CMV disease. It also may be useful in seronegative transplant recipients receiving a seropositive donor organ, although the benefit of chemo prophylaxis may surpass that of vaccine. HIV-infected patients with CMV retinitis who relapse under either ganciclovir or foscarnet benefit from subsequent combination therapy, rather than switching to the other drug. However, the cost is high in terms of quality of life. Intravitreal therapy for CMV retinitis is very efficacious, suggesting that drug delivery is a problem in systemic therapy. However, intravitreal therapy does not protect against the development of CMV retinitis in the contralateral eye or from CMV disease elsewhere. Therefore, systemic therapy should be added. CMV disease of the CNS should be diagnosed early and treated agressively, possible with combination therapy. A diagnosis of CMV disease should be based on a compatible clinical picture and the demonstration of CMV in CSF by DNA or antigen assays which are more sensitive than culture.

Animals↗
PubMed2001

Control of multiply resistant cocci: do international comparisons help?

Antibiotic resistance has become a worldwide problem. However, the reasons for the uneven geographic distribution of antibiotic-resistant microorganisms are not fully understood. For instance, there are striking differences in the epidemiology of multiresistant gram-positive cocci between the USA and Germany. According to recent reports, the prevalence of high-level penicillin-resistant pneumococci (PRP), meticillin-resistant Staphylococcus aureus (MRSA), and vancomycin-resistant enterococci (VRE) in clinically relevant isolates of hospitalised patients in the USA and Germany are: PRP, 14% versus less than 1%; MRSA, 36% versus 15%; and VRE, 15% versus 1%. These disparities may be explained by several determinants: (1) diagnostic practice and laboratory recognition (all three pathogens); (2) clonal differences and pathogen transmissibility (VRE); (3) antibiotic prescribing practices (all three pathogens); (4) population characteristics, including extensive daycare exposure in the USA (PRP); (5) cultural factors (all three pathogens); (6) factors related to the health-care and legal system (all three pathogens); and (7) infection-control practices (MRSA and VRE). Understanding these determinants is important for preventing further spread of multiresistant cocci within the USA. A rational approach to national surveillance is urgently needed in Germany to preserve the favourable situation and decrease MRSA transmission. Finally, we suggest that a macro-level perspective on antibiotic resistance can broaden the understanding of this worldwide calamity, and help prevent further dissemination of multiply resistant microorganisms.

Anti-Bacterial Agents↗
PubMed2000

Bactericidal action of high-power Nd:YAG laser light on Escherichia coli in saline suspension.

Infra-red light (1064 nm) from a high-power Nd:YAG laser caused more than 90% loss of viability of Escherichia coli during exposures that raised the temperature of PBS suspensions of the bacteria to 50 C in a thermocouple-equipped cuvette. In contrast, there was minimal loss of viability after heating the same suspensions to 50 degrees C in a water-bath, or in a PCR thermal cycler. The mechanism of laser killing at 50 degrees C was explored by differential scanning calorimetry, by laser treatment of transparent and turbid bacterial suspensions, and by optical absorbency studies of E. coli suspensions at 1064 nm. Taken together, the data suggested that the bactericidal action of Nd:YAG laser light at 50 degrees C was due partly to thermal heating and partly to an additional, as yet undefined, mechanism. Scanning electron microscopy revealed localized areas of surface damage on laser-exposed E. coli cells.

Colony Count, Microbial↗
PubMed1984

Production of a Biosurfactant from Torulopsis bombicola.

Two types of carbon sources-carbohydrate and vegetable oil-are necessary to obtain large yields of biosurfactant from Torulopsis bombicola ATCC 22214. Most of the surfactant is produced in the late exponential phase of growth. It is possible to grow the yeast on a single carbon source and then add the other type of substrate, after the exponential growth phase, and cause a burst of surfactant production. This product is a mixture of glycolipids. The maximum yield is 70 g liter, or 35% of the weight of the substrate used. An economic comparison demonstrated that this biosurfactant could be produced significantly more cheaply than any of the previously reported microbial surfactants.

Journal Article↗
PubMed1992

Antibiotic-resistant pneumococci in the United Kingdom.

Pneumococcal pneumonia and meningitis remain common infections with significant morbidity and mortality. For many years, penicillins or cephalosporins, erythromycin and chloramphenicol have been the mainstay of chemotherapy for these and other pneumococcal infections. Resistance to these antimicrobial agents has increased worldwide and resistant pneumococci are now isolated with increasing frequency in the United Kingdom. This article reviews the results of antimicrobial susceptibility and serotyping studies carried out over the last five years on UK isolates of Streptococcus pneumoniae referred to the Streptococcus and Antibiotic Reference Laboratories of the Division of Hospital Infection for serotyping or confirmation of antibiotic resistance. During this period there has been a marked increase in the referral of pneumococcal isolates resistant to one or more of the antimicrobials commonly used for treatment. The implications for antimicrobial therapy and vaccination policy are discussed.

Drug Resistance, Microbial↗
PubMed2006

Life's unity and flexibility: the ecological link.

The small size, ubiquity, metabolic versatility and flexibility, and genetic plasticity (horizontal transfer) of microbes allow them to tolerate and quickly adapt to unfavorable and/or changing environmental conditions. Prokaryotes are endowed with sophisticated cellular envelopes that contain molecules not found elsewhere in the biological world. Although prokaryotic cells lack the organelles that characterize their eukaryotic counterparts, their interiors are surprisingly complex. Prokaryotes sense their environment and respond as individual cells to specific environmental challenges; but prokaryotes also act cooperatively, displaying communal activities. In many microbial ecosystems, the functionally active unit is not a single species or population (clonal descendence of the same bacterium) but a consortium of two or more types of cells living in close symbiotic association. Only recently have we become aware that microbes are the basis for the functioning of the biosphere. Thus, we are at a unique time in the history of science, in which the interaction of technological advances and the exponential growth in our knowledge of the present microbial diversity will lead to significant advances not only in microbiology but also in biology and other sciences in general.

Adaptation, Physiological↗
PubMed1997

Drug resistance among Mycobacterium tuberculosis isolates in Lebanon.

OBJECTIVE: To determine the prevalence and patterns of drug resistance among Mycobacterium tuberculosis isolates recovered from tuberculosis (TB) cases in Lebanon. DESIGN: A total of 96 isolates were collected from the same number of TB cases between October 1994 and December 1995. These isolates were obtained from cases with newly diagnosed (81.3%) and previously treated (18.7%) cases of TB, and tested against isoniazid (INH), rifampicin (RIF), streptomycin (STM) and ethambutol (ETH), using the BACTEC-TB susceptibility procedure and system. RESULTS: The male to female ratio was 2:1 and the mean ages of males and females were almost similar, 34.1 and 32.7 years, respectively. Resistance to one or more drugs was found in 25 of 96 (26%) isolates. The overall percentages of single drug resistance against INH, RIF, STM and ETH were 23.9%, 12.5%, 7.3% and 3.1%, respectively. These percentages were higher, for all drugs, in isolates recovered from previously treated compared to new cases of TB: INH (50% vs 17.9%), RIF (33.3% vs 7.7%), STM (22.2% vs 3.8%) and ETH (11.1% vs 1.3%). Of the 25 resistant isolates, 11 were resistant to one drug only (10 to INH and 1 to STM), 10 were resistant to two drugs (7 to INH and RIF, 2 to INH and STM, 1 to STM and RIF), 2 were resistant to three drugs (1 to INH, RIF and ETH, 1 to INH, RIF and STM) and 2 were resistant to the four tested drugs. CONCLUSION: These data show that M. tuberculosis isolates in Lebanon have high rates of single and multidrug resistance, and speaks for the need to establish surveillance and monitoring programs in this country as part of the global effort to control TB.

Adult↗
PubMed1982

Nonspecific and cooperative binding of lectins to microorganisms.

Binding of lectins to microbial cell walls was investigated by fluorimetric titration and Scatchard plot. Data were correlated with agglutinability. Concanavalin A and lectins of wheat germ, soybean, pea, lentil, and peanut were tested against Escherichia coli. Micrococcus luteus, Lactobacillus plantarum, and Bacillus subtilis. In cases where binding occurred, it was either nonspecific or positively cooperative. Agglutination was observed only in those combinations of lectin and microorganism that showed positive cooperative binding, suggesting a definite relation between binding and agglutination. Lectins binding to the same carbohydrate did not necessarily bind to the same microorganism, confirming the complexity of the lectin-receptor bond.

Agglutination↗
PubMed1994

Receptors on phagocytic cells involved in microbial recognition.

There are two general concepts that we hope to have stressed concerning the recognition of microbes by phagocytic cells. The first is the concept of receptor redundancy and receptor cooperatively. Multiple receptors on leukocytes often participate in a given microbial recognition event. This concept can be illustrated by leishmania promastigotes that utilize both mannose receptors and Mac-1 to bind efficiently to macrophages. Likewise, macrophages use receptors for both IgG and complement to phagocytize encapsulated bacteria. This cooperativity between multiple receptors often changes the apparent affinity of the receptors for their ligand. Consequently the physiology of these receptors is altered. Fibronectin ligation, for example, results in the internalization of C3b-coated particles by the CR1. The second concept concerns the transduction of specific cellular signals following receptor ligation. Often, the receptor to which a microbe binds orchestrates many of the subsequent intracellular events during phagocytosis by transducing specific cellular signals. Some receptors, for example the mannose and Fc gamma-receptors, are particularly well suited to direct particles to phagolysosomes and trigger a respiratory burst, whereas other receptors, for example the CR1, may not. Indeed, from this perspective, one can view the immune response as being designed to target microbes preferentially to those receptors on phagocytic cells capable of making the appropriate cellular responses. In the case of leishmania, phagocytosis mediated by the Fc gamma receptors leads to parasite killing even by resident macrophages, while complement-mediated phagocytosis leads to parasite survival.

Amino Acid Sequence↗
PubMed1990

[Cooperation between the urologist and microbiologist in the diagnosis and treatment of sepsis. II. The most common microbial species and their sensitivity to antimicrobial drugs in sepsis at the Urologic Clinic of the Medical School Hospital].

The authors investigated the spectrum of aetiological agents and their sensitivity to antimicrobial substances in 52 patients with septicaemia at the Urological Clinic in Hradec Králové during 1984-1987. They found a predominating number of Gram-negative bacteria (82%). The most frequent agent producing sepsis was Klebsiella pneumoniae (19X), its source were in 52% the urinary pathways and 16% the cannula in the subclavian vein. In nine instances the aetiological agent was Escherichia coli and 5 times Proteus mirabilis. The above microorganisms are the most important pathogenic organisms of the urinary pathways. In all cases of bacteriaemia urosepsis was involved. The source of sepsis caused by Pseudomonas aeruginosa (7X) was in 43% the urinary tract, in particular in conjunction with instrumental procedures and in 14% a cannula in the subclavian vein. The most effective antimicrobial substance in Gram-negative bacteraemia in the investigated group was amicacin (100%); high sensitivity was recorded also in colistin. In Gram-positive bacteriaemia, where most frequently enterococci were isolated (6X), ampicillin and vancomycin were most effective.

Adult↗
PubMed1991

Draft results of a workshop to develop guidelines for studies involving microbial incidence or populations in the oral cavity.

The following five outlines are the results to date of the Workshop held in Rockville, Maryland, in January, 1990. The topics considered in these outlines are: (1) validation of immunological and/or nucleic acid identification probes, (2) cross-calibration of methods and/or laboratories for multi-laboratory cooperative studies, (3) choosing methods for identifying or describing microbial populations appropriate to the scientific question asked, (4) microbial ecology methods (e.g., population dynamics) for the oral cavity studies, and (5) epidemiological methods (e.g., incidence, risk factor analysis) for oral microbial studies. Each topic was considered by two independent groups of participants and later rationalized into one. These outlines are meant to be working outlines for evolution of a set of guidelines to advise on designing studies with microbial incidence and/or population components. We are publishing this preliminary version to elicit comment and criticism from people who did not attend the Workshop. (Attendance at the Workshop was necessarily limited by both space and funds). Some of the topic outlines have been condensed to save Journal space. The full document is available on request. The next stage will be an open forum to gather and discuss further amplification of the "Guidelines", planned for April 17, 1991, Acapulco, Mexico, in conjunction with the IADR/AADR Meeting. Written comments and requests for further information should be sent to the Workshop organizer (MIK) at the above address.(ABSTRACT TRUNCATED AT 250 WORDS)

DNA, Bacterial↗