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Biomedical subjects

S R Pattyn

Publications and source records attributed to S R Pattyn.

At least 19 recordsLinked to original sources

Monkeypoxvirus infections.

During and after the smallpox eradication campaign, human cases of monkeypox appeared in West and Central Africa, as isolated cases or as small epidemics. Since inter-human transmission has never or only very exceptionally been documented, monkeypox does not represent a serious threat to humans. The virus reservoir is among tree squirrels living in the tropical rain forests of Africa and humans are infected by hunting, killing and skinning these animals. However, the modernization of society lessens human contact with the virus reservoir. Since the eradication of smallpox, stocks of variola virus have been maintained; whether these stocks should now be destroyed is a political question, which is seriously compromised by mistrust between countries.

Animals↗

[To live happily, we live secretly. The knowledge of virus reservoirs is essential for the fight against infectious diseases].

The concept of virusreservoir is defined and illustrated. It corresponds to the site where the microorganisms survive "cachés et heureux". The definite control of infectious diseases consists, whenever possible, of the elimination of the responsible organisms from their reservoir. Frequently the virusreservoir was originally thought to be located in the proximity of man, but later investigations showed many reservoirs to be situated at much greater ecological distance. In many situations the phenomenon of latency plays an important role. This phenomenon is badly understood and a better understanding of its mechanisms could offer means to combat the microorganisms and the diseases they cause.

Animals↗

Comparison of two PCRs for detection of Mycobacterium ulcerans.

Two nested PCRs for the detection of Mycobacterium ulcerans were compared by using a collection of 65 clinical specimens. The first method amplifies the gene coding for 16S rRNA, and the second method amplifies a repetitive DNA sequence. The sensitivities of bacterioscopy, culture, 16S rRNA gene PCR, and repetitive-sequence PCR were 29, 34, 80, and 85%, respectively. Compared to the 16S rRNA gene PCR, the repetitive-sequence PCR was faster, easier to perform, and less expensive.

Bacteriological Techniques↗

[Yersinia pestis. Bacteriology].

The author discusses the evolution in the classification of the bacterium, responsible for plague: first a classification based on phenotypic characteristics, later based on genotypic characteristics, to finally arrive at an evolutionist classification. He treats the seven species of the genus Yersinia that can be distinguished by DNA hybridization. He examines the issue of sequencing and decoding the chromosome and mentions research regarding the phenomenon that the metabolism of the organisms modifies as a reaction to signals of their changing environment. Furthermore the author discusses the efforts to characterize the strains of Y. pestis (antiqua, medievalis and orientalis). Finally he comments on the discovery of a multiresistant strain, isolated in 1995 in Madagascar.

Bacteriological Techniques↗

[Infectious diseases, the veritable pandora's box].

The past few years, much attention has been given to the problems regarding new and emerging infectious diseases. Four groups may be considered: (1) new agents discovered among the causes of classical medical syndromes, these do not constitute new dangers but decrease the proportion of unknown causes within these syndromes; (2) increased importance of infectious agents resulting from modified ways of living or production procedures; (3) the really new agents, the spread of which is generally favoured by the same factors and (4) organisms with acquired resistance against antibiotics and pesticides. There is need for extended epidemiological surveillance, that can be improved in our country by better collaboration between different organisations. Most importantly epidemiological surveillance should be organized on an European level with the entire support of our regional and federal authorities.

Communicable Diseases↗

Evaluation of the Gen-Probe amplified Mycobacterium tuberculosis direct test for the routine diagnosis of pulmonary tuberculosis.

A total of 624 respiratory specimens from 543 patients (418 Belgian, 110 Rwandan, and 15 Colombian patients) were tested for the presence of Mycobacterium tuberculosis by the Mycobacterium Tuberculosis Direct Test (MTDT, Gen-Probe). Compared to culture, the MTDT on 497 samples of sputum or broncho-alveolar lavage from Belgium had a sensitivity, specificity and positive and negative predictive value of 86.4%, 96.0%, 50.0% and 99.3% respectively. The pooled results for Rwanda (112 specimens) and Colombia (15 specimens) were 97.8%, 65.7%, 88.2%, 92% respectively. After resolution of discrepant results by taking into account the clinical data, the results for the Belgian patients were 86.9%, 96.2%, 52.6%, 99.3% respectively, and for the Rwandan-Colombian patients 98.1%, 100%, 100% and 92% respectively. Results could be improved by testing more than one specimen from each patient and the inclusion of an internal control to detect inhibitors of the reaction. Culture remains necessary for drug susceptibility tests and the isolation and identification of non-tuberculous mycobacteria.

Belgium↗

Rapid and economical method for species identification of clinically significant coagulase-negative staphylococci.

Four methods for the species identification of coagulase-negative staphylococci in the medical microbiology laboratory were compared with 444 consecutive isolates. The methods included (i) the reference method based on growth tests, (ii) API ID 32 Staph (bioMérieux), (iii) Staph-Zym (Rosco), and (iv) a rapid 4-h method developed in our laboratory (UZA method). The last method is based on the detection within 4 h of enzymatic activity of heavy bacterial suspensions in three substrate solutions (nongrowth tests). For 16.5% of the isolates some supplementary growth tests read after 24 h had to be added to the enzyme data for satisfactory identification. The reference method failed to identify four isolates. Of the 440 isolates identified by the reference method, API ID 32 Staph, Staph-Zym, and the UZA method correctly identified 419 (95.2%), 429 (97.5%), and 430 (97.7%) and misidentified 8 (1.8%), 4 (0.9%), and 1 (0.2%), respectively. Staphylococcus epidermidis, S. haemolyticus, S. lugdunensis, S. schleiferi, and S. capitis were identified with an accuracy of 98 to 100% by all the systems tested. S. capitis subsp. ureolyticus was not recognized by the API ID 32 system because the biochemical profiles for it are not yet included in the corresponding database. Whereas API ID 32 identified all 13 S. warneri isolates, both Staph-Zym and the UZA method missed 2 of these. S. hominis was identified with the least accuracy by the API ID 32 system (26 of 39 isolates), whereas the UZA and Staph-Zym methods identified 36 of the isolates belonging to this species. The UZA method did not identify any of the S. cohnii, S. xylosus, S. lentus, and S. sciuri strains, since it included no discriminatory tests for these species, because they are extremely rarely found in humans. Of all 440 isolates tested, the UZA method failed to identify 9 and misidentified 1 other. Eighty-one percent of the isolates were identified within 4 h and 97.7% were identified after 24 h, at considerably less expense than by the API ID 32 Staph and Staph-Zym methods.

Bacterial Typing Techniques↗

Congenital pneumonia due to Mycoplasma pneumoniae.

A case of probable vertical transmission of Mycoplasma pneumoniae is presented. The presence of M pneumoniae was demonstrated by the polymerase chain reaction (PCR) in the nasopharyngeal aspirate of a newborn who developed pneumonia shortly after birth. This result was confirmed by performing a second PCR, amplifying another part of the genome of M pneumoniae. It is concluded that M pneumoniae can be added to the long list of pathogens known to cause congenital pneumonia.

Base Sequence↗

Classification of leprosy cases under field conditions in Bangladesh. I. Usefulness of skin-smear examinations.

In 2 non-governmental organization projects in Bangladesh 244 new leprosy patients were classified in the field according to clinical criteria. Skin smears were taken at 4 standardized sites and at the most active peripheral lesion, where a biopsy was also taken. Comparison of the clinical field classification with the results of the skin smears and biopsies gives a sensitivity of 92.1% for the clinical criteria, but a specificity of only 41.3%. The skin-smear results, on the other hand, have a sensitivity of 88.4% and a specificity of 98.1%. Thus, skin smears may contribute considerably to the operational classification of leprosy patients under field conditions. Quality control of the peripheral laboratory is essential. Appropriate site selection for the smear taking will also contribute to increased performance. Analysis of the skin-smear results suggests that the policy of taking smears at standardized sites should be abandoned in favour of the earlobes and active peripheral lesions.

Bacteriological Techniques↗

Classification of leprosy cases under field conditions in Bangladesh. II. Reliability of clinical criteria.

In 2 non-governmental organization projects 244 new leprosy patients in Bangladesh were classified in the field according to clinical criteria i.e. number of skin lesions and number of enlarged nerves. Comparison of these classification results with the results of skin smears and biopsies yielded a sensitivity (for detection of a MB case) of 92.1%, but the 'unconfirmed MB rate' amounted to 52.6%. In order to improve the reliability of the operational classification, several additional clinical criteria were investigated. It was found that neither the presence of anaesthesia in the skin lesions nor the presence of grade 2 disabilities or peripheral anaesthesia or voluntary muscle testing (VMT) impairment contributed to an improved classification. Counting the number of body areas showing signs of leprosy, which had proven very useful in other programmes, did not result in a more reliable classification in the 2 projects in Bangladesh. The presence of clinical signs of lepromatous leprosy, more specifically nodules or diffuse infiltration, could be a useful addition to the classification criteria. If the sensitivity must remain higher than 90%, the lowest 'unconfirmed MB rate' obtainable in Bangladesh, using clinical criteria only, is 46.4%, for a sensitivity of 91.0%. However, the inclusion of skin-smear results in the classification criteria could improve the sensitivity to 96.6% and lower the 'unconfirmed MB rate' to 40.3%. A reduction in MB overclassification will result in more efficient and more cost-effective leprosy control programmes.

Bacteriological Techniques↗

Positive inotropic effect of Streptococcus faecalis in isolated cardiac muscle.

Infective endocarditis is caused by bacterial colonization of the endocardium. Because endocardium modulates mechanical performance of subjacent myocardium, we studied acute effects of bacteria on isolated cardiac muscle and on the functional role of the endocardium. Bacteria, grown in broth at 37 degrees C, were added at increasing concentrations (10(2) to 10(6) bacteria/ml) to cat papillary muscles in Krebs-Ringer solution (1.25 mM Ca2+, 35 degrees C). The endocardial surface was damaged by exposing muscles to a stream of dry air for 30 s. Streptococcus (Enterococcus) faecalis induced significant increases in total peak isometric twitch tension (TT) and maximal velocity of unloaded shortening (Vmax) and significant decreases in time to TT (TtTT) and time to half isometric twitch tension decline (RT 1/2), both before and after removal of endocardial endothelium. This response could also be elicited with bacterial filtrate, after boiling the filtrate or after extracting the polysaccharides from it with KIO4. Increasing Ca2+ concentrations progressively reduced the response to the filtrate. Propranolol slightly, although not significantly, diminished the effects on TT and Vmax while abolishing the effects on TtTT and on RT 1/2. By contrast, Streptococcus bovis and Staphylococcus aureus did not affect TT or Vmax but induced a slight but significant decrease in TtTT at the highest concentration of bacteria. Accordingly, the filtrate of Strep. faecalis induces a positive inotropic effect. The active component is neither a protein nor a polysaccharide, and its effect may be partly beta-adrenoceptor mediated. Strep. bovis and Staph. aureus have negligible acute effects on contractility.

Adrenergic beta-Antagonists↗

A randomized clinical trial of two single-dose treatments for paucibacillary leprosy.

We compared 2 single-dose regimens for the treatment of paucibacillary leprosy in a randomized clinical trial in Zaïre. The regimens were: C2 (rifampicin 40 mg/kg and 1200 mg clofazimine once) and C4 (rifampicin 40 mg/kg, clofazimine 100 mg, DDS 100 mg and ethionamide 500 mg once). An analysis of the results of patients enrolled between May 1987 and December 1988, with a maximum follow-up of 4 years, is presented. A total of 622 patients were enrolled and 14 paucibacillary and 1 multibacillary relapses occurred. The overall paucibacillary relapse rate was 2.4 per 100 person years. This relapse rate was higher for older patients as well as for patients with 3 or more lesions. The probability of cure at 3 years is 0.816 for C2 and 0.823 for C4, the difference not being statistically significant. The probability of cure at 3 years with either regimen is higher for patients with 1 or 2 lesions (0.872) than for patients with 3 or more lesions (0.787), and it is higher for patients with a bacterial index of 0 (0.831) than for patients with a bacterial index of 1 (0.699). These results are compared to other studies. We also discuss the potential of single-dose treatment regimens for paucibacillary leprosy.

Adolescent↗

[Plague in Zaire].

Two endemic foci of plague have been discovered in Zaïre, the first in the Ituri in 1928, the other in North-Kivu in 1938. They are situated in the region of the great East-African Rift and are adjacent to the Ugandan focus, identified in 1877. A strict surveillance of these endemic foci makes it possible to state that, between 1928 and 1959, 632 cases of plague have been diagnosed in the Ituri, or 20 a year, and 190 in the N-Kivu, or 8 a year. Since then several flare ups have been notified. This situation is very remote from the "black death" concept. Yersinia pestis presents, besides its bipolar staining, many other characteristics such as the indispensable presence of iron to produce virulence, or the fermentation of glycerine and reduction of nitrates as parameters for the identification of 3 biovars, corresponding with a specific geographic distribution: antiqua, medievalis, orientalis or maritima. The antigenic structure has been discussed and also the role of plasmids. Plague is a disease of rats, a variegated gathering of rodents with different degrees of tolerance and sensitiveness to Y.pestis, living in a frail equilibrium. The multimammate houserat was in the Ituri the principal agent until the black rat Rattus rattus invaded the region and a new balance came into being. The frequent changes in taxonomy of Mastomys caused uncertainties. The transmission is due to fleas subject to a blocking of their ventriculum by Y.pestis. Fleas play an active part in the process. Man is only a casual intruder. The pathogenicity is related to its invasiveness and its intracellular localization in macrophages and other R.E. cells, in which Y.pestis can survive. The bubo is characteristic of the disease. In Zaïre a septicaemic tendency has been observed, with a possible involvement of the C.N.S. and of the lungs. The latter may produce among the surrounding relatives primary pneumonic plague. The clinical diagnosis ought to be confirmed by bacteriologic investigation of the puncture fluid of the bubo, the blood, and when necessary the C.S.F. or the sputum by culture and/or animal inoculation. The treatment became very efficient since the availability of sulfamides and later antibiotics: aminoglycosides, chloramphenicol, tetracyclines. A timely administration ensures practically recovery. As soon as Y.pestis was identified vaccination was put into practice and in the first place by killed germs (Haffkine's lymph) to day with formalized F1, for mass vaccination live attenuated strains were used: Tjiwidej (Otten), E.V. (Girard), K120 (Grasset).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

Detection of herpes simplex virus in the cerebrospinal fluid of patients with encephalitis using the polymerase chain reaction.

Herpes simplex encephalitis is a neurologic emergency demanding immediate institution of specific therapy in order to prevent mortality. Diagnosis, however, is a complex matter with controversy existing over the appropriateness of brain biopsy. We report the demonstration of herpes simplex virus DNA by means of the polymerase chain reaction (PRC) in the cerebrospinal fluid of 3 patients with herpes simplex encephalitis. One of the patients suffered from brain-stem encephalitis with high intensity signals in the pons on magnetic resonance imaging, the second reported case of this entity. The PCR for herpes simplex on a control series of cerebrospinal fluid of 20 patients with other central nervous system infections was negative. PCR of cerebrospinal fluid offers a sensitive, specific and rapid diagnosis of herpes simplex encephalitis, making brain biopsy unnecessary. Still, the importance of strict measures to prevent contamination cannot be stressed enough. It is possible that due to the high sensitivity of the PCR, herpes simplex may be found in other infectious syndromes of the central nervous system.

Adult↗

Comparative evaluation of the Rapid ID 32A kit system, miniaturized standard procedure and a rapid fermentation procedure for the identification of anaerobic bacteria.

The RAPID ID 32A and a rapid fermentation procedure were compared with a miniaturized standard procedure for the identification of 102 isolates of anaerobic bacteria belonging to 11 genera. The miniaturized standard procedure identified all 102 isolates at the genus level and 90 at the species level. The rapid fermentation procedure failed to identify 12 and 24 isolates at the genus and species levels respectively and is unsatisfactory. The RAPID ID 32A system misidentified 4 isolates (4%) at the genus level, 3 of which could have been avoided if the results of the Gram stain, the fundamental procedure in medical microbiology, had been taken into account. The system correctly identified 89 isolates at the species level. Since it does not produce species identifications within the genera Mobiluncus and Veillonella of which 7 and 2 isolates respectively were included in the study, the percentage of correct identifications at the species level is 96.7% (90/93). The RAPID ID 32A system is about 25 times more expensive than the miniaturized standard procedure if the investment for a gas chromatograph is not taken into account.

Bacteria, Anaerobic↗

Detection of Mycobacterium leprae by the polymerase chain reaction in nasal swabs of leprosy patients and their contacts.

Nose swabs from 4 paucibacillary (PB) and 8 multibacillary (MB) leprosy patients and their contacts were tested for the presence of Mycobacterium leprae by two polymerase chain reactions (PCR); 30% of the samples contained inhibitors for the PCR, 1 of 52 (1.9%) swabs and 13 of 164 (7.9%) swabs were positive for M. leprae among contacts of PB and MB patients, respectively. Since this difference is not significant, and some positives were found among contacts of MB patients treated and cured of their infection, it is concluded that the observed infections are community acquired.

DNA, Bacterial↗