Impact de l’épidémie de COVID-19 sur la couverture vaccinale antigrippale du personnel hospitalier

Introduction

La couverture vaccinale (CV) antigrippale des soignants hospitaliers en France est faible et très inférieure aux objectifs de l’OMS (≥ 75 %). Afin de réduire le potentiel impact cumulé d’une épidémie de grippe concomitante de celle de COVID-19, la HAS a réaffirmé la nécessité d’augmenter la CV antigrippale auprès des professionnels de santé. Nous avons cherché à évaluer l’impact de l’épidémie de COVID-19 sur la CV antigrippale du personnel hospitalier pour la saison 2020-2021.

Matériels et méthodes

Nous avons réalisé un questionnaire informatique diffusé dans six centres hospitaliers du 12 janvier au 28 février 2021. La diffusion s’est faite via la messagerie électronique des salariés de l’hôpital et des étudiants des 2^e et 3^e cycles de médecine ainsi que par une affiche contenant un QR-code renvoyant au questionnaire en ligne et disposé dans certains services.

Résultats

Parmi les 1930 réponses analysées, 74,6 % étaient celles de femmes (n = 1440) et la moyenne d’âge était de 40 ans. Il y avait 1492 professionnels de santé (77,3 %) : 457 médecins, 205 internes, 63 sages-femmes (SF), 314 infirmiers, 106 cadres, 89 aides-soignants (AS), 81 pharmaciens ou préparateurs en pharmacie et 177 personnes exerçant une autre profession paramédicale. Il y avait 148 étudiants (7,7%) et 290 personnes exerçant une profession non médicale (15,0 %). La CV antigrippale du personnel hospitalier répondant était de 65,1% (n = 1257) contre 41,3% (n = 798) l’année précédente soit une augmentation de 57,5% de la CV. Les hommes étaient plus vaccinés (74,9 %) que les femmes (61,8 %). Les personnes de 50 ans et plus étaient vaccinées à 72,6 % (n = 373) contre 62,4% (n = 884) pour les moins de 50 ans. La CV des professionnels de santé était de 68,1% (n = 1016), contre 44,6 % l’année passée (n = 666). Les médecins et internes étaient vaccinés respectivement à 81,8 % (n = 374) et 80,0 % (n = 164), les SF à 60,3 % (n = 38), les infirmiers à 55,1 % (n = 173), les AS à 43,8 % (n = 39) et les cadres à 76,4 % (n = 81). Les pharmaciens et préparateurs en pharmacie étaient vaccinés à 66,7% (n = 54), les étudiants à 64,9 % (n = 96), le personnel exerçant une autre profession paramédicale à 52,5 % (n = 93) et ceux exerçant une profession non médicale à 50,0 % (n = 145). Les trois principales motivations à la vaccination antigrippale étaient de se protéger (90,1 % [n = 1133]), de protéger ses proches (88,7 % [n = 1115]) et de protéger les patients (86,7 % [n = 1090]). Parmi les 535 personnes vaccinées cette année mais non vaccinées l’année dernière, 58,9% (n = 315) ont estimé que l’épidémie de COVID-19 les avait incités à se faire vacciner.

Conclusion

Nous constatons une forte augmentation de la CV antigrippale quels que soient la classe d’âge, le genre et la profession. Les médecins sont les professionnels qui se vaccinent le plus, atteignant même l’objectif de CV établit par l’OMS. Il semble que l’épidémie de COVID-19 et les mesures d’incitation vaccinale antigrippale associées aient contribué à cette augmentation.

[Experimental studies of long-term effect of a detergent disinfecting for surface on a strain of Escherichia coli]

We offer three complementary, original methods and reproducibles to study the antibacterial and long-term effect of a detergent disinfecting for surfaces commercialized lately in France. Long-term activity noticed-effect is compared with that of other products. We first study the curves of growth of a strain of Escherichia coli put in presence with the surface of the wells of a microplate beforehand and for several days (from D-10 to D0), coated with disinfecting detergents. Another method consisted on surfaces firstly treated from D-10 to D0 by the one or the other product to be tested, which are artificially contaminated in a standardized manner by a velvet footprint with a suspension of E. coli. The surviving microbes are counted after transfer on a Rodac plate. Finally, doorhandles are cleaned and disinfected with the product. The natural bacterial recolonization doorhandles is studied by daily Rodac plate within a week. These studies allow to prove that Bacoban introduces a bactericidal activity on E. coli with an long-term effect for at least 10 days. The most competitive products have a bacteriostatic effect during nine to 10 days, but bactericidal effect only during two days. This bactericidal long-term effect may be particularly interesting in hospital hygiene for the biocleaning of the most manipulated surfaces and should restrict the role of bacterial reservoir of certain surfaces participating in care or near of the patients.

[Methods for microbiological control of textiles]

Our laboratory is requested more and more by the establishments of health and the industrial laundries for the microbiological realization of control on the textile articles after completion. We checked the effectiveness of the techniques of the bacteriol prints or rodac and the bacterial extraction after maceration for the realization of these controls. The output of extraction of the bacteriol prints applied to woven material samples sterilized and then artificially contaminated by a titrated Staphylococcal suspension is lower than 1%. The technique recommended and largely used for the study in particular of the contamination of the blouses of doctor in the establishments of health thus does not appear to be relevant. We propose for the quality control of the linen a technique of maceration then extraction by the ultra sounds whose output is evaluated to 62% which requires to sacrifice the controled textile article. The choice of the bacteriological techniques as controls ultimate of a procedure must be carried out carefully to meet the needs for quality. Conclusions, when with the effectiveness of a process, deduced from results obtained by a bad method could be wrongfully reassuring.

Étude de l'efficacité d'un produit détergent désinfectant pour sols et surfaces sur les souches bactériennes isolées à partir de l'environnement hospitalier

We studied the sensitivity of the hospital environmental bacterial strains to Surfanios, which is a detergent and disinfectant product for surfaces. This product is used in our establishment since nearly 10 years. This work which relates to 425 bacterial strains proposes to study the possible evolution of the resistance of the bacteria under the pressure of a product biocide used since many years without the change of active ingredient as recommended in pharmaceutical and agroalimentary industry. We developed a micromethod to study the sensitivity of many bacterial strains simultaneously into a 96 wells microplaque. All the Staphylococcus aureus strains (N = 20) and Staphylococcus with coagulase negative (N = 308) as 78 Acinetobacter sp. strains remain very sensitive to Surfanios according to our study. Target dilution, which is the last dilution not allowing the bacterial growth, is much lower than the manufacturer recommended use dilution. For the Pseudomonas aeruginosa strains tested, target dilution is equal or higher than the dilution of use. Rather than to propose the rotation or the alternation of the products, we recommend the use of Surfanios for the bionettoyage of dry surfaces which might be contaminated by Staphylococcus sp. or Acinetobacter sp. and the use of another product or Surfanios at a higher concentration, active on Pseudomonas sp. to disinfect wet surfaces which are possible reservoirs for the opportunist bacteria of the hydrous flora.

[Factors associated with early invasive strategy in patients with acute coronary syndrome. A multicenter study]

OBJECTIVES

To identify the factors associated with early cardiac catheterization in patients with a non ST-segment elevation acute coronary syndrome.

METHODS

We analyzed data collected by retrospective chart review for 208 patients presenting at seven French hospitals with an acute coronary syndrome (chest pain at rest within 24 h prior to presentation with positive cardiac markers and/or electrocardiographic changes) between January and March 2005.

RESULTS

Eighty-seven patients (42%) were first admitted to hospitals with cardiac catheterization facilities. One hundred ten patients (53%, 95% confidence interval [95% CI], 46-60) underwent early cardiac catheterization less than 48 h following presentation. In addition to presentation at hospitals with catheterization facilities, factors independently associated with early catheterization included positive cardiac markers in patients first admitted to hospitals without catheterization facilities (adjusted odds ratio [aOR] 34.5, 95% CI, 4.4-268.0) and diabetes mellitus (aOR, 0.4, 95%CI, 0.2-0.9). With the exception of positive cardiac markers, no risk factors comprising the TIMI risk score were associated with increased odds of early cardiac catheterization. During the index hospital stay, six patients (3%) died, seven patients (3%) had pulmonary edema, three patients (1%) had major or minor bleeding, and none had ST segment elevation myocardial infarction.

CONCLUSION

Despite the dissemination of international guidelines, the use of early cardiac catheterization remains related to initial presentation at hospitals with catheterization facilities rather than risk assessment in patients with a non ST-segment elevation acute coronary syndrome.

[Bacteriological sampling of surfaces: importance of the step of enrichment and the choice of the culture media]

This study tested the efficiency of four different procedures for isolating bacteria found on hospital surfaces. The techniques studied use both rich and poor media with or without enrichment in nutritive broth. The sampling of surfaces in hospital care departments was carried out using a dampened sterile flue brush. Bacteria samples were then placed on TCSA agar plates (method 1) and blood agar plates (GS) (method 2) before immersion in a nutritive broth for enrichment. The following day, the broth was used to produce two new media: TCSA (method 3) and GS (method 4). For each sample, we established the global amount of different bacterial species isolated by all 4 methods combined. These values were then used as a reference to evaluate the efficiency of each technique. 360 smears were carried out, and a total of 718 bacterial strains were isolated. Methods 1 and 2 (without enrichment) permitted the isolation of 10.86 and 13.37% respectively of the total number of strains. Methods 3 and 4, with preliminary enrichment, made it possible to isolate 69.08% of bacterial strains on TCSA medium and 90.53% on GS medium. The combination of the enrichment stage and an enriched culture medium lead to an excellent output that highlights and identifies bacteria isolated from samples taken from hospital surfaces.

Epidemiological study of invasive pulmonary aspergillosis in a haematology unit by molecular typing of environmental and patient isolates of Aspergillus fumigatus

In order to determine the possible relationship between environmental contamination by Aspergillus fumigatus and occurrence of invasive aspergillosis, a one-year prospective study was carried out in the haematology ward of Hautepierre Hospital, Strasbourg, France. During the study period, 21 environmental isolates and 26 clinical isolates of A. fumigatus were collected. Each was genotyped using a random amplification of polymorphic DNA (RAPD) technique. Thirty-four distinct profiles were identified by RAPD analysis, indicating the great genetic diversity of A. fumigatus isolated from infected patients and from the environment. For two patients, RAPD analysis demonstrated concurrent infection by at least two different strains. In two cases, a genetic similarity was noted between isolates obtained from a patient and from the environment.

Effect of peracetic acid and aldehyde disinfectants on biofilm

The effects of two aldehyde (Cidex, Endosporine) and four peracetic acid (PAA) (Nu Cidex, Anioxyde 1000, Hydraseptic, Peralkan) disinfectants on an Escherichia coli biofilm model were studied. The biofilm was prepared in glass tubes, and evaluated indirectly using a colourimetric method. The ability of the disinfectants to fix or remove the biofilm from tubes was determined by their detergent activity (DA). The two aldehyde derivatives and two of the PAA (Nu Cidex, Anioxyde 1000) agents fixed the biofilm. However, the effects of Hydraseptic and Peralkan were equivalent to the control (sterile water). Regardless of their disinfectant activity, PAA agents display different DAs that could be used to select the weakest biofilm-fixing agents. Users should be concerned about the efficiency of the cleaning stage of medical devices, and when choosing a PAA product, non-fixing ability should be considered in addition to antimicrobial activity.

Effectiveness of detergent–disinfecting agents on Escherichia coli 54127 biofilm

Detergent-disinfecting agents (dD) are used daily for cleaning reused medical devices. We have devised a simple method to test dD detergent activity (DA) using an E. coli 54127 biofilm prepared in haemolysis glass tubes, which are cleaned with test dD, according to supplier's recommendations. Crystal violet 0.05% is used to colour the residual biofilm after dD (or tap water control) application. The biofilm quantification was made indirectly by measuring the absorbance of crystal violet at 585 nm. A measure of the detergent effectiveness called DA was calculated as the percentage reduction of colour from a tap water control. Fifteen products including enzymatic and non-enzymatic dDs were evaluated. Most enzymatic dDs gave a high DA, as did some non-enzymatic products. Thus, the view that enzymatic dDs are more effective than non-enzymatic dDs, put forward by some manufacturers, should be regarded with caution. The DA determination should help infection control teams choose, within the wide range of products available on the market, the most effective dD based on both its detergent and disinfecting activity.

Staphylococcus aureus isolated in cases of impetigo produces both epidermolysin A or B and LukE-LukD in 78% of 131 retrospective and prospective cases

Clinical symptoms of impetigo and staphylococcal scalded skin syndrome may not only be expressed as the splitting of cell layers within the epidermis but are often accompanied by some localized inflammation. Toxin patterns of Staphylococcus aureus isolates originating from patients with impetigo and also from those with other primary and secondary skin infections in a retrospective isolate collection in France and a prospective isolate collection in French Guiana revealed a significant association (75% of the cases studied) of impetigo with production of at least one of the epidermolysins A and B and the bicomponent leucotoxin LukE-LukD (P < 0.001). However, most of the isolates were able to produce one of the nonubiquitous enterotoxins. Pulsed-field gel electrophoresis (PFGE) of genomic DNA hydrolyzed with SmaI showed a polymorphism of the two groups of isolates despite the fact that endemic clones were suspected in French Guiana and France. The combination of toxin patterns with PFGE fingerprinting may provide further discrimination among isolates defined in a given cluster or a given pulsotype and account for a specific virulence. The new association of toxins with a clinical syndrome may reveal principles of the pathological process.

[What are the indications in France for vaccination against Japanese encephalitis?]

Japanese encephalitis is a mosquito-borne viral disease occurring in rural and rice-growing areas of Asia, where mosquitoes proliferate, transmitting the Flavivirus from viremic animals, mostly pigs, to humans. Japanese encephalitis has recently spread to previously non-affected regions, leading to serious outbreaks among non-immune populations. Although it has a high proportion of unsymptomatic infection, clinical encephalitis is usually severe, resulting in a very high mortality rate, and neurologic sequellae are common among survivors. Vaccines are used in several Asian countries. One of these vaccines is now available to French travellers, but only in international vaccination centres with an authorization from the French drug agency (Agence française de sécurité sanitaire des produits de santé). The aim of this paper is to clarify the recommendations for immunisation in each country of the affected regions. The area can be divided into three epidemiological zones, with tropical, subtropical and temperate characteristics. For the first two, vaccination is recommended before a long stay in a rural area, especially during the rainy season; in temperate climates, outbreaks occur in summer and autumn. However, local variations such as intensive rice-growing or development of pig breeding may interfere with these patterns. Long-term visitors should consult a local physician and prevention of mosquito bites is always recommended.

Analysis with a combination of macrorestriction endonucleases reveals a high degree of polymorphism among Bordetella pertussis isolates in eastern France

From 1990 to 1996, routine screening for whooping cough identified 399 patients with a calmodulin-dependent adenylate cyclase-positive test result and yielded 69 Bordetella pertussis isolates. None of the patients were fully vaccinated, and most were less than 6 months old. Analysis of total DNA by pulsed-field gel electrophoresis (PFGE) after XbaI, SpeI, or DraI macrorestriction yielded 19, 15, and 5 different patterns, respectively, whereas ribotyping failed to demonstrate any strain polymorphism. Discrimination among the isolates was improved by combining the PFGE profiles. Some patterns were more frequent, but the corresponding patients were not clearly epidemiologically related. The patterns for two strains obtained during a 3-month period from patients who were neighbors differed by the length of a single DNA fragment. These data strongly suggest that one type of isolate is widely spread throughout the world and is carried by individuals other than patients who develop a true illness.

[Pore-forming leukotoxins from Staphylococcus aureus: variability of the target cells and 2 pharmacological processes]

The staphylococcal bi-component leukotoxins constitute a family included in the super-family of the beta-sheet-structured pore-forming toxins. They may be produced by Staphylococcus aureus and by Staphylococcus intermedius and their target cells vary according to the molecules. The mode of action proceeds by the sequential binding of the class S proteins, then by that of the class F proteins at the surface of the membranes. Then, the activation of cellular calcium-channels precedes the pore formation which seems to be sensitive to several monovalent cations. The cell response is inflammatory and includes the neosynthesis as well as the secretion of leukotriene B4, interleukin -8, histamine. The injection of leukotoxins to rabbits generates cell chemotaxis , vasodilatation, and tissue necrosis. The association of the production of leukotoxins with clinical syndromes concerns several aspects of the pathology of S. aureus, and confers to these leukotoxins an important role of virulence factors.

A predicted beta-sheet from class S components of staphylococcal gamma-hemolysin is essential for the secondary interaction of the class F component

Site-directed mutagenesis was performed on genes encoding HlgA and HlgC, two of the three proteins expressed from the staphylococcal y-hemolysin locus, which originate two pore-forming toxins (HlgA + HlgB, HlgC + HlgB). As related proteins, HlgA and HlgC were found to bind first to cell membranes. Amino acid substitutions concerned residues that would predictably disrupt a 13 amino acid conserved beta-sheet of the Chou and Fasman secondary structure prediction. The mutation of a threonin into an aspartic acid residue from HlgA (T28D) and from HlgC (T30D) that would break this predicted N-terminal structure lowered dramatically the biological activities on purely lipidic vesicles, erythrocytes and polymorphonuclear cells. The change in secondary structure was confirmed by Fourier Transformed Infrared spectroscopy. The binding of mutated and native proteins at the same kind of sites onto polymorphonuclear cells was evidenced with flow cytometry and fluorescein-labelled anti-class S antibodies or wild type HlgA or HlgC. However, the subsequent binding of fluorescein-labelled HlgB to membrane-bound mutated HlgA or HlgC complexes was inhibited. In conclusion, the first binding of class S components is essential for the subsequent binding of class F components, and a predicted beta-sheet seems to be at least one of the functional domains involved.

Antral and fundic D-cell numbers in Helicobacter pylori infection

OBJECTIVES

Helicobacter pylori infection is associated with an exaggeration of gastrin release following meals or bombesin stimulation attributed to a defect of somatostatin secretion of antral D-cells. Nevertheless, these modifications of gastric physiology do not explain the increase of gastric acid secretion which is only observed in duodenal ulcer patients. The inhibitory effect of somatostatin secretion of fundic D-cells on parietal cells is well known. The aim of our prospective study was to compare the number of fundic D-cells and likewise the number of antral G-cells and D-cells between patients with duodenal ulcer and healthy subjects with and without H. pylori infection.

METHODS

The numbers of D-cells and G-cells were compared between 19 infected patients with duodenal ulcer and 20 healthy subjects, 10 with and 10 without H. pylori infection. Fundic mucosal biopsy specimens were examined using immunohistochemical techniques specific for the presence of somatostatin, antral mucosal biopsy specimens for the presence of gastrin and somatostatin.

RESULTS

The number of G-cells was significantly lower (P = 0.0012) in duodenal ulcer patients by comparison with infected subjects and controls. The number of antral D-cells was significantly less (P < 0.0001) in duodenal ulcer patients (mean of 10 random fields = 0.45 +/- 0.04) than in either asymptomatic infected patients (0.65 +/- 0.07) or uninfected controls (0.88 +/- 0.10). The number of fundic D-cells was significantly lower (P < 0.0001) in duodenal ulcer patients (mean = 0.20 +/- 0.03) than in either asymptomatic infected subjects (0.29 +/- 0.05) or controls (0.73 +/- 0.09); here the difference between the two groups of infected subjects was not significant. Multivariate analysis showed that the presence of H. pylori infection of the fundic mucosa did not influence the number of fundic D-cells.

CONCLUSION

Changes in the number of fundic and antral D-cells induced by H. pylori infection did not explain abnormalities of gastric acid secretion usually observed in duodenal ulcer patients; it is suggested that pre-existing abnormalities in the regulation of parietal cell or increase of parietal cell mass are involved.

Flow cytometric determination of endocytosis of viable labelled Legionella pneumophila by Acanthamoeba palestinensis

Endocytosis of fluorescently labelled cells of Legionella pneumophila (L. pneumophila) by free-living Acanthamoeba palestinensis (A. palestinensis) has been studied using flow cytometry. L. pneumophila cells were labelled with CM-DiI, a lipophilic fluorescent probe under conditions that did not modify viability. Coculturing the bacteria with amoebae was accompanied by rapid endocytosis; after 5 min, 90% of the amoebae had internalized bacteria. This percentage remained unchanged during further coculture, but the number of bacteria ingested per amoeba increased. Moreover, the number of ingested bacteria was found to be dependent on the size of the amoeba. The validity of the internalization analyzed by flow cytometry was confirmed by observation using epifluorescence and phase contrast microscopy. CM-DiI labelling associated with flow cytometry provides a very valuable technique for the determination of bacteria endocytosis by free-living amoeba.

[Role of hygiene and bacteriological laboratories in the management of an epidemic of Enterobacter aerogenes multiresistant to antibiotics]

We describe a multiresistant Enterobacter aerogenes outbreak in an intensive care-unit. An epidemiology study based on phenotypic characters (species diagnosis and antibiotype) was completed by a genotypic study (pulsed field electrophoresis) to confirm bacterial clonality. The hygiene laboratory proposed numerous preventive measures to limit bacterial dispersion. We describe the role of bacteriologists, hygienists and medical staff to stop the bacterial dispersion.

[Isolation of Helicobacter pylori: necessity of control of transport conditions]

The aim of the study was the influence of transport conditions of antrum biopsies on the diagnostis of Helicobacter pylori infection by mean of bacteriological methods. We compare bacteriological to anatomopathological methods of Helicobacter pylori infection during two periods which differed by the transport conditions for antrum biopsies. During the first period (P1), 57 specimens were carried to the laboratory at room temperature and physiological serum immersion was inconstant. During the second period (P2), 56 specimens were all correctly immerged into 5 ml of physiological serum, in a 15 mm diameter tube which was vertically maintained in ice. Anatomopathological methods were considered as the reference method for the diagnostic of Helicobacter pylori infection. The sensibility of bacteriological culture was increased from 59% (P1) to 84% (P2) (p < 0.05) when specificity was unchanged. Furthermore sensibility of bacteriological direct examination was increased from 41% (P1) to 61% (P2). Complete biopsy immersion and ice transport of samples appear as necessary conditions for the optimal diagnostic of Helicobacter infections by mean of bacteriological methods.

Application of flow cytometry in toxinology: pathophysiology of human polymorphonuclear leukocytes damaged by a pore-forming toxin from Staphylococcus aureus

The pore-forming activity of leukocidin (PVL) secreted by Staphylococcus aureus has been investigated on human white cells by flow cytometry techniques. This two-component toxin induced morphological modifications of neutrophils and monocytes as detected by forward light scattering measurements, but was inactive on lymphocytes. These modifications were the consequence of pore formation through the cell membrane leading to its permeabilization. In the absence of calcium, PVL formed pores large enough to allow ethidium ions to penetrate the cells and become fluorescent by intercalating nucleic acids. In the presence of calcium, the pores were too small for ethidium entry but allowed an influx of calcium as shown by the increase in fluorescence of Fluo-3 loaded in the cells. This increase in intracellular calcium concentration induced the activation of neutrophils by PVL as shown by the liberation of their granule content measured by a decrease in side light scattering. Furthermore, ethidium fluorescence was used to discriminate the cells sensitive to PVL, and the analysis of differentiated HL-60 cells and cells obtained from a case of chronic myeloid leukemia led to the conclusion that myeloid cells become sensitive to PVL during differentiation to the metamyelocyte stage.

Pore formation by a two-component leukocidin from Staphylococcus aureus within the membrane of human polymorphonuclear leukocytes

The effects of the Staphylococcus aureus leukocidin (PVL), a two-component non-hemolytic toxin, were investigated on the membrane permeability of human polymorphonuclear leukocytes (PMNs). In the absence of extracellular Ca2+, the fluorescence of ethidium bromide added to the extracellular medium increased after PVL application in a concentration-dependent manner and no variations in the free intracellular [Ca2+] of Fura2-loaded PMNs were detected. In the presence of extracellular Ca2+, the fluorescence of ethidium was not modified but the free intracellular [Ca2+] of PMNs increased after application of PVL in a concentration-dependent manner. The time lag observed before an increase in the ethidium fluorescence was longer than the time lag observed before a Fura2 fluorescence increase. Simultaneous recordings of the two probes fluorescence variations have shown the protective effect of Ca2+ and Zn2+ and the closing of the pore by 50 mM Ca2+ or 2 mM Zn2+. Moreover, the effect of Ca2+ could be reversed by the addition of EGTA. In the presence of 1 mM extracellular Ca2+ or 0.8 mM extracellular Zn2+, the pore induced by PVL had an ionic size allowing Ca2+, Mn2+, Zn2+ and Mg2+ fluxes. The addition of antibodies against either component of PVL inhibits the permeabilization provoked by the toxin even after it was initiated. It is concluded that leukocidin from S. aureus is a pore-forming toxin which, under physiological conditions ([Ca2+] = 1 to 1.5 mM), provokes the formation of an ion-sized pore inducing an increase in the free intracellular Ca2+ which may activate PMN functions.

Detection of Legionella spp. in bronchoalveolar lavage fluids by DNA amplification

By using Taq polymerase, DNA amplification of a specific fragment of the macrophage infectivity potentiator (mip) gene from Legionella pneumophila was used to detect Legionella spp. in bronchoalveolar lavage (BAL) fluid specimens. We were able to detect DNAs from all 30 L. pneumophila strains tested (serogroups 1 to 14), L. micdadei, and L. bozemanii serogroup 1. DNA from bacteria of other species tested and DNA from human leukocytes were not amplified by this procedure. After optimization of the conditions for DNA extraction from BAL fluid, a 2-ml sample of BAL fluid seeded with 25 CFU/ml tested positive after DNA amplification. A total of 68 frozen BAL fluid specimens sent to the laboratory because of suspected legionellosis were tested in a retrospective study. The eight culture-positive samples were all positive after specific DNA amplification. Among 60 culture-negative samples, 7 were positive after amplification. Of these seven samples, four were from patients who had presented a typical clinical history of legionellosis; the samples had antibody titer increases of 2 dilutions. For the three remaining samples, serological diagnosis of legionellosis in the patients from whom the samples were obtained could not be documented, and although the causative agent of these pulmonary infections was not determined, the clinical features of the patients were in accordance with legionellosis.

Doppler-free continuous-wave phase-conjugate spectrum of SF6 by resonant degenerate four-wave mixing at 10.6 microm

A phase-conjugate signal has been obtained in SF(6) with a peak reflectivity of 1.2 x 10(-3) by using a cw CO(2) laser operating on the P(16) line. The degenerate four-wave mixing spectrum exhibits a Doppler-free structure with 2-MHz resolution. When the reflectivity spectrum is compared with the saturated-absorption spectrum, matching peaks in the reflectivity spectrum are found over an 80-MHz bandwidth.