Traçologie: la trace, vecteur fondamental de la police scientifique

Les développements technologiques et la spécialisation des laboratoires de police scientifique et de science forensique éloignent de plus en plus les spécialistes de leur objet d'étude: la trace comme vestige, avec toutes les difficultés associées à son caractère unique, non contrôlé qui lui donnent la dimension d'une recherche historique plus qu'expérimentale. Pour paraphraser Kirk (Kirk 1963), la discipline qui touche à l'exploitation des traces fait appel à une pléthore de moyens techniques, mais manque cruellement de recherches et de développements fondamentaux. Cela se reflète d'ailleurs dans l'absence de rigueur quant au vocabulaire utilisé et une confusion dans la nomenclature, par exemple entre l'empreinte (référent) et la trace, l'échantillon (statistiquement sélectionné) et le spécimen, l'analyse, qui n'est pas que chimique, la contamination et la pollution. Ce manque de rigueur traverse la littérature scientifique et cet essai vise à clarifier la terminologie et à proposer un emploi sémantique strict du vocabulaire et des notions de base qui touchent aux fondements de la discipline.

Characteristics and determinants of outcome of hospital-acquired bloodstream infections in intensive care units: the EUROBACT International Cohort Study.

PURPOSE: The recent increase in drug-resistant micro-organisms complicates the management of hospital-acquired bloodstream infections (HA-BSIs). We investigated the epidemiology of HA-BSI and evaluated the impact of drug resistance on outcomes of critically ill patients, controlling for patient characteristics and infection management. METHODS: A prospective, multicentre non-representative cohort study was conducted in 162 intensive care units (ICUs) in 24 countries. RESULTS: We included 1,156 patients [mean ± standard deviation (SD) age, 59.5 ± 17.7 years; 65 % males; mean ± SD Simplified Acute Physiology Score (SAPS) II score, 50 ± 17] with HA-BSIs, of which 76 % were ICU-acquired. Median time to diagnosis was 14 [interquartile range (IQR), 7-26] days after hospital admission. Polymicrobial infections accounted for 12 % of cases. Among monomicrobial infections, 58.3 % were gram-negative, 32.8 % gram-positive, 7.8 % fungal and 1.2 % due to strict anaerobes. Overall, 629 (47.8 %) isolates were multidrug-resistant (MDR), including 270 (20.5 %) extensively resistant (XDR), and 5 (0.4 %) pan-drug-resistant (PDR). Micro-organism distribution and MDR occurrence varied significantly (p < 0.001) by country. The 28-day all-cause fatality rate was 36 %. In the multivariable model including micro-organism, patient and centre variables, independent predictors of 28-day mortality included MDR isolate [odds ratio (OR), 1.49; 95 % confidence interval (95 %CI), 1.07-2.06], uncontrolled infection source (OR, 5.86; 95 %CI, 2.5-13.9) and timing to adequate treatment (before day 6 since blood culture collection versus never, OR, 0.38; 95 %CI, 0.23-0.63; since day 6 versus never, OR, 0.20; 95 %CI, 0.08-0.47). CONCLUSIONS: MDR and XDR bacteria (especially gram-negative) are common in HA-BSIs in critically ill patients and are associated with increased 28-day mortality. Intensified efforts to prevent HA-BSIs and to optimize their management through adequate source control and antibiotic therapy are needed to improve outcomes.

Epidemiology of uveitis in children over a 10-year period.

OBJECTIVES: The aim of the present study is to investigate the demographics, aetiologies, complications, treatments and visual outcomes in paediatric uveitis patients in the French-speaking part of Switzerland. METHODS: Chart review of all patients diagnosed with uveitis before the age of 16 years, presenting to two tertiary referral centres (uveitis and paediatric rheumatology clinics) in Lausanne, Switzerland, between 2000 and 2009. RESULTS: Seventy-nine children (37 girls) were identified, 62 living in Switzerland, 15 in Europe and 2 in North Africa. Median age at first symptoms was 9.0 years (range 1.5-15.8 years), with a median follow-up time of 1.8 years (0-8 years). Both eyes were involved in 51 patients (64.6%). The course was acute in 30.4%, chronic in 60.8% and recurrent in 8.9%. Anterior uveitis occurred in 39.2%, intermediate in 32.9%, posterior in 22.8% and panuveitis in 5.1%. The three main diagnoses were idiopathic uveitis (34.2%), JIA-related uveitis (22.8%) and toxoplasmic retinochoroiditis (15.2%). During the last follow-up visit, the visual acuity (VA) was ≥8/10 in 72% of all eyes with a measurable VA. Cataract (8%), ocular hypertension/glaucoma (8%) and macular fibrosis (4%) were the three most common severe complications. Systemic steroids were given to 56% and biological agents to 24% of patients with inflammatory uveitis. CONCLUSIONS: Uveitis in children can be a devastating disease. A strict classification of aetiologies and a tight collaboration between paediatric rheumatologists and ophthalmologists are important to ensure early control of ocular inflammation and improve long-term visual prognosis.

Complex organization of CTF/NF-I, C/EBP, and HNF3 binding sites within the promoter of the liver-specific vitellogenin gene.

Vitellogenin genes are expressed specifically in the liver of female oviparous vertebrates under the strict control of estrogen. To explain this tissue-specific expression, we performed a detailed analysis of the Xenopus laevis vitellogenin gene B1 promoter by DNase I footprinting and gel mobility-shift assays. We characterized five binding sites for the ubiquitous factor CTF/NF-I. Two of these sites are close to the TATA-box, whereas the others are located on both sides of the estrogen responsive unit formed by two imperfect estrogen response elements. Moreover two liver-enriched factors, C/EBP and HNF3, were found to interact with multiple closely spaced proximal promoter elements in the first 100 base pairs upstream of the TATA-box. To confirm the physiological significance of this in vitro analysis, in vivo DNase I footprinting experiments were carried out using the ligation-mediated polymerase chain reaction technique. The various cis-elements characterized in vitro as binding sites for known transcription factors and more particularly for liver-enriched transcription factors are efficiently recognized in vivo as well, suggesting that they play an important role in the control of the liver-specific vitellogenin gene B1 expression.

Abortion trends 1990-1999 in a Swiss region and determinants of abortion recurrence.

OBJECTIVE: To assess age- and nationality-specific trends in abortion rates over the last decade, and to describe women's characteristics, identifying risk factors for repeated abortion. METHODS: From 1990-1999, the Health Department of Canton Vaud (Switzerland) received 13'857 abortion requests from residents aged 14-49. Population data were obtained to compute rates. RESULTS: Both the number of abortions (1400 annually) as well as their rate (8.9 per thousand women [95% confidence interval (CI) 7.3-10.5]) were stable over the decade in question. The rate of abortion for foreign women, especially from ex-Yugoslavia and Africa, was twice that for Swiss women. Half of the requests came from single women, 43% had a low education level, and half were childless. The main reason for requesting termination of pregnancy was psychosocial (93%). The mean gestational age was 7.7 weeks (SD +/- 2.3), but 96% of requests were submitted before 12 weeks. Sixty-three percent of women reported that they had used no contraception, 36% the condom and 17% the pill. Among requests, the adjusted risk of repeated abortion (22% of abortion candidates) was greater among divorced/separated/widowed women (odds ratio [OR] 1.9 [95% CI 1.5-2.4]), unemployed women (OR 1.8 [95% CI 1.5-2.1]), and those who had not attended university (OR 1.6 [95% CI 1.1-2.2]). CONCLUSIONS: Although Swiss law only permitted abortion under strict conditions, this procedure was widely available in Vaud, which nevertheless has one of the lowest rates worldwide. Efforts must be intensified to ensure universal access to family planning services, especially for foreign women and adolescents. Professionals should also target "repeaters" to provide personalised counselling.

Chirurgie [Trends in surgery]

More than the number of real novelties, trends and preliminary results characterise the annual development in surgery. The wealth and diversity of topics to be covered require arbitrary choices, therefore not necessarily complete. The constant development of choledocolithiasis management, dominated by minimal invasive technology, treatments of unusual nature of two frequent proctological conditions, fistulae and haemorrhoids, the increasing importance of metabolic bariatric surgery, as well as the strict rules of effective melanoma treatment, represent as many directions in which the operating procedure, although unseen, continue to gain quality and security.

Histone deacetylase inhibitors impair antibacterial defenses of macrophages

Les déacetylases d'histones (HDACs) déacétylent non seulement les histones, ce qui a généralement pour effet d'augmenter la transcription et l'expression génique, mais également d'autres protéines comme par exemple des protéines de choc thermique (HSP90), la tubuline alpha, certains récepteurs aux stéroïdes ainsi que de nombreux facteurs de transcription (NF-kB p65, Sp1, etc.). Ainsi les HDACs participent au contrôle de nombreux processus cellulaires. Les inhibiteurs des HDACs (ou HDACi), de part leur capacité à induire la différenciation cellulaire et l'apoptose, sont parmi les anti-cancéreux les plus prometteurs en cours de développement pour dans le traitement des néoplasies solides et hématologiques. Récemment, l'activité anti-inflammatoire et immuno- modulatrice des HDACi a été mise en évidence et exploitée avec succès pour le traitement de pathologies auto-immunes dans des modèles précliniques. L'effet des HDACi sur la réponse immunitaire innée restant largement inconnu, nous avons entrepris la première étude d'envergure dans ce domaine. Dans un premier article, nous démontrons que les HDACi inhibent l'expression de nombreux gènes (récepteurs aux produits microbiens, cytokines, chimiokines, molécules d'adhésion et co-stimulatrices, facteurs de croissance, etc.) impliqués dans les défenses anti¬infectieuses in vitro. En accord avec ces données, les HDACi augmentent la mortalité d'animaux infectés dans des modèles de pneumonie et de candidose bénignes. De manière congruente, les HDACi protègent les animaux de mortalité induite par choc toxique et septique en inhibant la réponse inflammatoire exubérante qui caractérise ces pathologies (Roger T. et al., Blood 2011). Afin de caractériser plus en détails l'influence des HDACi sur la réponse immunitaire innée, nous avons également analysé l'impact de deux HDACi, l'acide valproïque (VPA) et la trichostatin A (TSA), sur les principaux mécanismes de défenses antimicrobiennes des macrophages. Dans un second article (Mombelli et al., Journal of Infectious Diseases 2011), nous rapportons que la VPA et la TSA diminuent la capacité des macrophages à phagocyter et à détruire les bactéries Gram-positives Staphylococcus aureus et Gram-négatives Escherichia coli. En accord avec ces données, les HDACi inhibent l'expression de molécules impliquées dans la phagocytose comme les récepteurs éboueurs (Msr 1 et CD14) et de type lectine (Dectin 1), ainsi que les récepteurs aux opsonines (intégrines). Par ailleurs, les HDACi interfèrent avec l'expression de différentes sous unités de la NADPH oxydase (gp91p"ox, p22 phox, p47 phox, p40 phox, p67 phox et Rac2) et de l'oxyde nitrique (NO) synthétase inductible (iNOS), qui sont responsables de la production de dérivés oxygénés (ROS) et nitrogénés (NO) essentiels à la destruction des microorganismes dans le phagolysosome. En résumé, cette étude décrit des mécanismes par lesquels les HDACi diminuent la capacité d'ingérer et de détruire les bactéries, et ainsi augmentent la susceptibilité aux infections. Globalement, nos données indiquent que les HDACi sont de puissants anti¬inflammatoires qui pourraient favoriser la survenue d'infections chez les patients cancéreux traités avec ces drogues, comme semble par ailleurs le suggérer des études cliniques rapportées dans la littérature. Nous proposons un suivi clinique infectieux strict chez les patients traités avec ces agents.

Résistance aux antibiotiques chez les pneumocoques [Pneumococcal antibiotic resistance].

In 1875, 7 years prior to the description of the Koch bacillus, Klebs visualized the first Streptococcus pneumoniae in a pleural fluid. Since then, this organism has played a determinant role in biomedical science. From a biological point of view, it was largely implicated in the development of passive and active immunization by serotherapy and vaccination, respectively. Genetic transformation was also first observed in S. pneumoniae, leading to the discovery of DNA. From a clinical point of view, S. pneumoniae is still today a prime cause of otitis media in children and of pneumonia in all age groups, as well as a predominant cause of meningitis and bacteremia. In adults, bacteremia is still entailed with a mortality of over 25%. Although S. pneumoniae remained very sensitive to penicillin for many years, penicillin-resistance has emerged and increased dramatically over the last 15 years. During this period of time, the frequency of penicillin-resistant isolates has increased from &lt; or = 1% to frequencies varying from 20 to 60% in geographic areas as diverse as South Africa, Spain, France, Hungary, Iceland, Alaska, and numerous regions of the United States and South America. In Switzerland, the current frequency of penicillin-resistant pneumococci ranges between 5 and &gt; or = 10%. The increase in penicillin-resistant pneumococci correlates with the intensive use of beta-lactam antibiotics. The mechanism of resistance is not due to bacterial production of penicillinase, but to an alteration of the bacterial target of penicillin, the so-called penicillin-binding proteins. Resistance is subdivided into (i) inter mediate level resistance (minimal inhibitory concentration [MIC] of penicillin of 0.1-1 mg/L) and (ii) high level resistance (MCI &gt; or = 2 mg/L). The clinical significance of intermediate resistance remains poorly defined. On the other hand, highly resistant strains were responsible for numerous therapeutical failures, especially in cases of meningitis. Antibiotics recommended against penicillin-resistant pneumococci include cefotaxime, ceftriaxone, imipenem and in some instances vancomycin. However, penicillin-resistant pneumococci tend to present cross-resistances to all the antibotics of the beta-lactam family and could even become resistant to the last resort drugs mentioned above. Thus, in conclusion, the explosion of resistance to penicillin in pneumococci is a ubiquitous phenomenon which must be fought against by (i) a strict utilization of antibiotics, (ii) the practice of microbiological sampling of infected foci before treatment, (iii) the systematic surveillance of resistance profiles of pneumococci against antibiotics and (iv) the adequate vaccination of populations at risk.

Antibiotic susceptibility of Estrella lausannensis, a potential emerging pathogen.

Estrella lausannensis is a new Chlamydia-related bacterium, belonging to the Criblamydiaceae family. As suggested by its species name, this bacterium harbors a peculiar star shape. E. lausannensis is able to infect a wide range of amoebal, fish and mammalian cell lines. Moreover, seroprevalence of 2.9% was reported in children and in women with tubal pathology, showing that humans are commonly exposed to this recently discovered strict intracellular bacteria considered as a potential pathogen. Antibiotic susceptibility was determined using two approaches: qPCR and cellular mortality assay. Antibiotics classically used against intracellular bacteria were tested, including β-lactams, fluoroquinolones, cyclines and macrolides. We showed that E. lausannensis is resistant to β-lactams and fluoroquinolones, and sensitive to cyclines. Interestingly, E. lausannensis is slightly resistant to azithromycin with a MIC of 2 μg/ml, which is 10 fold higher compared to Waddlia chondrophila and Parachlamydia acanthamoebae MIC's. A single A2059C mutation in 23S rRNA gene could be responsible for this unexpected resistance.

Introducing a new MRI classification of lumbar spinal stenosis based on cross-sectional morphology of the dural sac : 37

Introduction: Measures of the degree of lumbar spinal stenosis (LSS) such as antero-posterior diameter of the canal, and dural sac cross sectional area vary, and do not correlate with symptoms or results of surgery. We created a grading system, comprised of seven categories, based on the morphology of the dural sac and its contents as seen on T2 axial images. The categories take into account the ratio of rootlet/ CSF content. Grade A indicates no significant compression, grade D is equivalent to a total myelograhic block. We compared this classification with commonly used criteria of severity of stenosis. Methods: Fifty T2 axial MRI images taken at disc level from 27 symptomatic LSS patients undergoing decompressive surgery were classified twice by two radiologists and three spinal surgeons working at different institutions and countries. Dural sac cross-sectional surface area and AP diameter of the canal were measured both at disc and pedicle level from DICOM images using OsiriX software. Intraand inter-observer reliability were assessed using Cohen's, Fleiss' kappa statistics, and t test. Results: For the morphological grading the average intra-and inter observer kappas were 0.76 and 0.69+, respectively, for physicians working in the study originating country. Combining all observers the kappa values were 0.57 ± 0.19. and 0.44 ± 0.19, respectively. AP diameter and dural sac cross-sectional area measurements showed no statistically significant differences between observers. No correlation between morphological grading and AP diameter or dural sac crosssectional areawas observed in 13 (26%) and 8 cases (16%), respectively. Discussion: The proposed morphological grading relies on the identification of the dural sac and CSF better seen on full MRI series. This was not available to the external observers, which might explain the lower overall kappa values. Since no specific measurement tools are needed the grading suits everyday clinical practice and favours communication of degree of stenosis between practising physicians. The absence of a strict correlation with the dural sac surface suggests that measuring the surface alone might be insufficient in defining LSS as it is essentially a mismatch between the spinal canal and its contents. This grading is now adopted in our unit and further studies concentrating on relation between morphology, clinical symptoms and surgical results are underway.

Propranolol in infantile haemangioma: simplifying pretreatment monitoring.

BACKGROUND: Infantile haemangiomas (IHs) are very common vascular tumours. Propranolol is at present the first-line treatment for problematic and complicated haemangioma. In accordance with a Swiss protocol, children are monitored for 2 days at the start of the treatment to detect possible side effects of this drug. Our study advocates a simplification of the pretreatment monitoring process. METHODS: All children with a problematic and complicated haemangioma treated with propranolol between September 2009 and September 2012 were included in the study. All patients were hospitalised under constant nurse supervision for 48 hours at the start of the treatment and subjected to cardiac and blood measurements. The dosage of propranolol was 1 mg/kg/day on the first day and 2 mg/kg/day from the second day. Demographic data, clinical features, treatment outcome and complications were analysed. RESULTS: Twenty-nine infants were included in our study. Of these, 86.2% responded immediately to the treatment. There were no severe adverse reactions. Six patients presented transient side effects such as bradycardia, hypotension after the first dose and hypoglycaemia later. No side effects occurred after the second dose. Treatment was never interrupted. CONCLUSION: Propranolol (a β-blocker) is a safe treatment for problematic IH. Side effects may occur after the first dose. A strict 48 hour monitoring in hospital is expensive and may be unnecessary as long as the contraindications for the drug are respected.

Towards robust network based complex systems : from evolutionary cellular automata to biological models

Abstract Sitting between your past and your future doesn't mean you are in the present. Dakota Skye Complex systems science is an interdisciplinary field grouping under the same umbrella dynamical phenomena from social, natural or mathematical sciences. The emergence of a higher order organization or behavior, transcending that expected of the linear addition of the parts, is a key factor shared by all these systems. Most complex systems can be modeled as networks that represent the interactions amongst the system's components. In addition to the actual nature of the part's interactions, the intrinsic topological structure of underlying network is believed to play a crucial role in the remarkable emergent behaviors exhibited by the systems. Moreover, the topology is also a key a factor to explain the extraordinary flexibility and resilience to perturbations when applied to transmission and diffusion phenomena. In this work, we study the effect of different network structures on the performance and on the fault tolerance of systems in two different contexts. In the first part, we study cellular automata, which are a simple paradigm for distributed computation. Cellular automata are made of basic Boolean computational units, the cells; relying on simple rules and information from- the surrounding cells to perform a global task. The limited visibility of the cells can be modeled as a network, where interactions amongst cells are governed by an underlying structure, usually a regular one. In order to increase the performance of cellular automata, we chose to change its topology. We applied computational principles inspired by Darwinian evolution, called evolutionary algorithms, to alter the system's topological structure starting from either a regular or a random one. The outcome is remarkable, as the resulting topologies find themselves sharing properties of both regular and random network, and display similitudes Watts-Strogtz's small-world network found in social systems. Moreover, the performance and tolerance to probabilistic faults of our small-world like cellular automata surpasses that of regular ones. In the second part, we use the context of biological genetic regulatory networks and, in particular, Kauffman's random Boolean networks model. In some ways, this model is close to cellular automata, although is not expected to perform any task. Instead, it simulates the time-evolution of genetic regulation within living organisms under strict conditions. The original model, though very attractive by it's simplicity, suffered from important shortcomings unveiled by the recent advances in genetics and biology. We propose to use these new discoveries to improve the original model. Firstly, we have used artificial topologies believed to be closer to that of gene regulatory networks. We have also studied actual biological organisms, and used parts of their genetic regulatory networks in our models. Secondly, we have addressed the improbable full synchronicity of the event taking place on. Boolean networks and proposed a more biologically plausible cascading scheme. Finally, we tackled the actual Boolean functions of the model, i.e. the specifics of how genes activate according to the activity of upstream genes, and presented a new update function that takes into account the actual promoting and repressing effects of one gene on another. Our improved models demonstrate the expected, biologically sound, behavior of previous GRN model, yet with superior resistance to perturbations. We believe they are one step closer to the biological reality.

The hematology laboratory in blood doping (bd): 2014 update on the athlete biological passport (APB)

Introduction: Blood doping (BD) is the use of Erythropoietic Stimulating Agents (ESAs) and/or transfusion to increase aerobic performance in athletes. Direct toxicologic techniques are insufficient to unmask sophisticated doping protocols. The Hematological module of the ABP (World Anti-Doping Agency), associates decision support technology and expert assessment to indirectly detect BD hematological effects. Methods: The ABP module is based on blood parameters, under strict pre-analytical and analytical rules for collection, storage and transport at 2-12°C, internal and external QC. Accuracy, reproducibility and interlaboratory harmonization fulfill forensic standard. Blood samples are collected in competition and out-ofcompetition. Primary parameters for longitudinal monitoring are: - hemoglobin (HGB); - reticulocyte percentage (RET); - OFF score, indicator of suppressed erythropoiesis, calculated as [HGB(g/L) * 60-√RET%]. Statistical calculation predicts individual expected limits by probabilistic inference. Secondary parameters are RBC, HCT, MCHC-MCH-MCV-RDW-IFR. ABP profiles flagged as atypical are review by experts in hematology, pharmacology, sports medicine or physiology, and classified as: - normal - suspect (to target) - likely due to BD - likely due to pathology. Results: Thousands of athletes worldwide are currently monitored. Since 2010, at least 35 athletes have been sanctioned and others are prosecuted on the sole basis of abnormal ABP, with a 240% increase of positivity to direct tests for ESA, thanks to improved targeting of suspicious athletes (WADA data). Specific doping scenarios have been identified by the Experts (Table and Figure). Figure. Typical HGB and RET profiles in two highly suspicious athletes. A. Sample 2: simultaneous increases in HGB and RET (likely ESA stimulation) in a male. B. Samples 3, 6 and 7: "OFF" picture, with high HGB and low RET in a female. Sample 10: normal HGB and increased RET (ESA or blood withdrawal). Conclusions: ABP is a powerful tool for indirect doping detection, based on the recognition of specific, unphysiological changes triggered by blood doping. The effect of factors of heterogeneity, such as sex and altitude, must also be considered. Schumacher YO, et al. Drug Test Anal 2012, 4:846-853. Sottas PE, et al. Clin Chem 2011, 57:969-976.

Compensation for environmental damages under international law

ABSTRACT The purpose of this research is to clarify the contribution of international dispute adjudication mechanisms in regard to environmental protection. Most specifically, the study aims to identify and develop the criterion adopted by the international judge in relation to the compensation for environmental damages. In this perspective, the study identifies some gaps between international responsibility and environmental protection interests. The premise sustained all along the study is that compensation is determinant to conciliate environmental prerogatives with mechanisms of international adjudication, in particular the system of international responsibility. Supported by the analysis of treaties, international decisions and secondary sources, the thesis defends the idea that some elements of international law allow the adjudicator to adapt the compensation to attend certain environmental interests, creating a new approach which was entitled 'fair compensation'. The antithesis of this approach is the idea that compensation in international law is limited exclusively to the strict reparation of the material losses incurred by the victim. As a synthesis, the study defends the specificity of environmental damages in relation to other kind of damages that are subject to compensation under international law. The measure upon which compensation for environmental damages could be classified as a specific type of damage under international law remains to be determined. The main conclusion of the study is that the existing standard of compensation defined by the theory and practice of international law is impossible to be strictly respected in cases involving environmental damages. This limitation is mainly due to the complexity of the notion of environment, which is constantly conflicting with the anthropologic view of legal theory. The study supports the idea that the establishment of a 'fair compensation' which takes into account the political, legal and technical context of the environmental damage, is the best possible approach to conciliate internationally responsibility and environmental interests. This could be implemented by the observance of certain elements by the international judge/arbitrator through a case-by-case analysis.

Parachlamydia acanthamoebae, an emerging agent of pneumonia.

Parachlamydia acanthamoebae is a Chlamydia-like organism that easily grows within Acanthamoeba spp. Thus, it probably uses these widespread free-living amoebae as a replicative niche, a cosmopolite aquatic reservoir and a vector. A potential role of P. acanthamoebae as an agent of lower respiratory tract infection was initially suggested by its isolation within an Acanthamoeba sp. recovered from the water of a humidifier during the investigation of an outbreak of fever. Additional serological and molecular-based investigations further supported its pathogenic role, mainly in bronchiolitis, bronchitis, aspiration pneumonia and community-acquired pneumonia. P. acanthamoebae was shown to survive and replicate within human macrophages, lung fibroblasts and pneumocytes. Moreover, this strict intracellular bacterium also causes severe pneumonia in experimentally infected mice, thus fulfilling the third and fourth Koch criteria for a pathogenic role. Consequently, new tools have been developed for the diagnosis of parachlamydial infections. It will be important to routinely search for this emerging agent of pneumonia, as P. acanthamoebae is apparently resistant to quinolones, which are antibiotics often used for the empirical treatment of atypical pneumonia. Other Chlamydia-related bacteria, including Protochlamydia naegleriophila, Simkania negevensis and Waddlia chondrophila, might also cause lung infections. Moreover, several additional novel chlamydiae, e.g. Criblamydia sequanensis and Rhabdochlamydia crassificans, have been discovered and are now being investigated for their human pathogenicity.