Authors:Manja Boehm, Daniel Simson, Ulrike Escher, Anna-Maria Schmidt, Stefan Bereswill, Nicole Tegtmeyer, Steffen Backert, and Markus M. Heimesaat
Campylobacter jejuni is a major food-borne zoonotic pathogen, responsible for a large proportion of bacterial gastroenteritis cases, as well as Guillian-Barré and Miller-Fisher syndromes. During infection, tissue damage is mainly caused by bacteria invading epithelial cells and traversing the intestinal barrier. C. jejuni is able to enter the lamina propria and the bloodstream and may move into other organs, such as spleen, liver, or mesenteric lymph nodes. However, the involved molecular mechanisms are not fully understood. C. jejuni can transmigrate effectively across polarized intestinal epithelial cells mainly by the paracellular route using the serine protease high-temperature requirement A (HtrA). However, it appears that HtrA has a dual function, as it also acts as a chaperone, interacting with denatured or misfolded periplasmic proteins under stress conditions. Here, we review recent progress on the role of HtrA in C. jejuni pathogenesis. HtrA can be transported into the extracellular space and cleaves cell-to-cell junction factors, such as E-cadherin and probably others, disrupting the epithelial barrier and enabling paracellular transmigration of the bacteria. The secretion of HtrA is a newly discovered strategy also utilized by other pathogens. Thus, secreted HtrA proteases represent highly attractive targets for anti-bacterial treatment and may provide a suitable candidate for vaccine development.
Authors:Markus Krohn, Thomas Wanek, Marie-Claude Menet, Andreas Noack, Xavier Declèves, Oliver Langer, Wolfgang Löscher, and Jens Pahnke
ATP-binding cassette (ABC) transporters are of major importance for the restricted access of toxins and drugs to the human body. At the body's barrier tissues like the blood–brain barrier, these transporters are highly represented. Especially, ABCB1 (P-glycoprotein) has been a priority target of pharmaceutical research, for instance, to aid chemotherapy of cancers, therapy resistant epilepsy, and lately even neurodegenerative diseases. To improve translational research, the humanization of mouse genes has become a popular tool although, like recently seen for Abcb1, not all approaches were successful. Here, we report the characterization of another unsuccessful commercially available ABCB1 humanized mouse strain. In vivo assessment of transporter activity using positron emission tomography imaging revealed a severe reduction of ABCB1 function in the brain of these mice. Analyses of brain mRNA and protein expression showed that the murine Abcb1a gene is still expressed in homozygous humanized animals while expression of the human gene is minimal. Promoter region analyses underpinned that the introduced human gene might dysregulate normal expression and provided insights into the regulation of both transcription and translation of Abcb1a. We conclude that insertion of the human coding DNA sequence (CDS) into exon 3 instead of exon 2 most probably represents a more promising strategy for Abcb1a humanization.
The fever-inducing effect of lipopolysaccharides (LPS) is well known, and human blood is extremely responsive to this pyrogen. Recently, the safety of LPS-containing food supplements and probiotic drugs as immune-stimulants has been questioned, although these products are orally taken and do not reach the bloodstream undigested. The concerns are understandable, as endotoxaemia is a pathological condition, but the oral uptake of probiotic products containing LPS or Gram-negative bacteria does not pose a health risk, based on the available scientific evidence, as is reviewed here. The available methods developed to detect LPS and other pyrogens are mostly used for quality control of parentally applied therapeuticals. Their outcome varies considerably when applied to food supplements, as demonstrated in a simple comparative experiment. Products containing different Escherichia coli strains can result in vastly different results on their LPS content, depending on the method of testing. This is an inherent complication to pyrogen testing, which hampers the communication that the LPS content of food supplements is not a safety concern.
Authors:Kouassi N’Guessan, Timothée Ouassa, Anna S. Dean, Riccardo Alagna, Guy Damien Adagra, Valeri Ibode, Daniela M. Cirillo, and Jacquemin Kouakou
Setting: Tuberculosis (TB) drug resistance survey was conducted in 2016–2017 to estimate the burden of drug-resistant TB in Côte d'Ivoire.
Design: A cross-sectional cluster-based survey was conducted. All eligible smear positive patients were interviewed using a structured questionnaire to collect clinical and sociodemographic information and tested by the Xpert Mycobacterium tuberculosis/rifampicin (MTB/RIF) assay. If resistant to rifampicin, solid and liquid cultures were performed. Phenotypic drug susceptibility testing (DST) was conducted in liquid medium for rifampicin, isoniazid, ethambutol, streptomycin, ofloxacin, and amikacin.
Results: Of the 1105 sputum smear positive patients enrolled, 995 new and 100 previously treated patients were positive for Mycobacterium tuberculosis complex by Xpert. Proportion of patients with rifampicin resistance was 4.6% (95% CI: 2.4–6.7) and 22% (95% CI: 13.7–30.3), respectively, for new and previously treated patients. Second-line DST results were available for most rifampicin-resistant patients. None were resistant to amikacin, only two were ofloxacin-resistant. Apart from the antecedent of previously treatment for TB, no other risk factors for rifampicin resistance were detected.
Conclusion: Prevalence of rifampicin resistance among TB patients in Côte d'Ivoire is higher than that in other countries in the region. Surveillance of drug resistance, through an expanded GeneXpert network, and programmatic management of drug-resistant TB (PMDT) must be strengthened in Côte d'Ivoire.
Authors:Anabel Cruz-Romero, Cosme Alvarado-Esquivel, Dora Romero-Salas, Ángel Osvaldo Alvarado-Félix, Sokani Sánchez-Montes, Jesús Hernández-Tinoco, and Luis Francisco Sánchez-Anguiano
Purpose: This study aimed to determine the seroprevalence and correlates of Leptospira IgG antibodies in backyard pigs in the northern Mexican state of Durango. We performed a cross-sectional study of 305 backyard pigs. Anti-Leptospira IgG antibodies were detected using microscopic agglutination assay (MAT) with a panel of 12 Leptospira antigens.
Results: Overall, antibodies against Leptospira (any of the 12 Leptospira serovars examined) were found in 186 (61.0%) of the 305 pigs studied. Seropositive pigs were found on 80 (70.2%) of the 114 properties surveyed. The predominant serovar was Leptospira interrogans Pomona (n = 55); followed by Leptospira noguchii Lousiana and Leptospira santarosai Tarassovi (n = 53 each); L. interrogans Bataviae (n = 47); Leptospira biflexa Semaranga and L. interrogans Hebdomadis (n = 36 each); L. interrogans Pyrogenes (n = 30); L. interrogans Djasiman (n = 20); Leptospira borgpetersenii Ballum (n = 11); L. noguchii Panama and L. interrogans Canicola (n = 5 each); and L. borgpetersenii Mini (n = 2). Logistic regression showed that seropositivity was associated with low (<1000 m above sea level) altitude (odds ratio [OR] = 3.24; 95% confidence interval [CI]: 2.01–5.20; P < 0.001).
Conclusions: This is the first report of Leptospira exposure in backyard pigs in Mexico and of an association between Leptospira exposure in pigs and altitude. Backyard pigs represent a high-risk group for Leptospira exposure.
Urinary Tract Infection (UTI) is a worldwide phenomenon in modern times, in which the dependency on antibiotics for its treatment is increasing. The current study was conducted in order to find alternatives to antibiotics by investigating some commercial fruits for their antimicrobial activity. The fruits in this study included green apple (Malus domestica), papaya (Carica papaya), lemon (Citrus limon), and strawberry (Fragaria ananassa), which were used to prepare methanolic and ethanolic extracts through Soxhlet extraction technique. The extracts were used against bacteria that cause UTI, and five different strains were selected: E. coli (ATCC: 15922), E. coli (ATCC: 25922), Pseudomonas aeruginosa (ATCC: 27853), Enterococcus faecalis (ATCC: 29212), and Klebsiella pneumoniae. Antimicrobial tests of the extracts were conducted by following the agar well diffusion method, where ciprofloxacin was used as a positive control, and autoclaved distilled water was used as a negative control. Among the fruits, apple and papaya extracts did not show any zone of inhibition against any of the tested bacteria. However, both lemon and strawberry extracts showed inhibition zone against all of the mentioned bacteria. The ethanolic extracts of lemon and strawberry were more potent than their methanolic extracts. Lemon ethanolic extract showed the highest zone of inhibition against Pseudomonas aeruginosa (ATCC: 27853) (18.34 ± 0.58) and lowest one against Klebsiella pneumoniae (16.00 ± 1.00). Strawberry ethanolic extracts showed the highest zone of inhibition against Pseudomonas aeruginosa (ATCC: 27853) (16.33 ± 0.58) and the lowest one against Klebsiella pneumoniae (13.33 ± 0.58). As antibiotic resistance is paving the way for multi-drug resistant bacteria, the results of lemon and strawberry can be considered to be used as an antimicrobial agent in treating urinary tract infections.
Authors:Ulrike Escher, Eliezer Giladi, Ildikò R. Dunay, Stefan Bereswill, Illana Gozes, and Markus M. Heimesaat
The octapeptide NAP is well known for its neuroprotective properties. We here investigated whether NAP treatment could alleviate pro-inflammatory immune responses during experimental subacute ileitis. To address this, mice with a human gut microbiota were perorally infected with one cyst of Toxoplasma gondii (day 0) and subjected to intraperitoneal synthetic NAP treatment from day 1 until day 8 postinfection (p.i.). Whereas placebo (PLC) control animals displayed subacute ileitis at day 9 p.i., NAP-treated mice exhibited less pronounced pro-inflammatory immune responses as indicated by lower numbers of intestinal mucosal T and B lymphocytes and lower interferon (IFN)-γ concentrations in mesenteric lymph nodes. The NAP-induced anti-inflammatory effects were not restricted to the intestinal tract but could also be observed in extra-intestinal including systemic compartments, given that pro-inflammatory cytokines were lower in liver, kidney, and lung following NAP as compared to PLC application, whereas at day 9 p.i., colonic and serum interleukin (IL)-10 concentrations were higher in the former as compared to the latter. Remarkably, probiotic commensal bifidobacterial loads were higher in the ileal lumen of NAP as compared to PLC-treated mice with ileitis. Our findings thus further support that NAP might be regarded as future treatment option directed against intestinal inflammation.
In community ecology, randomization tests with problem specific test statistics (e.g., nestedness, functional diversity, etc.) are often applied. Researchers in such studies may want not only to detect the significant departure from randomness, but also to measure the effect size (i.e., the magnitude of this departure). Measuring the effect size is necessary, for instance, when the roles of different assembly forces (e.g., environmental filtering, competition) are compared among sites. The standard method is to calculate standardized effect size (SES), i.e., to compute the departure from the mean of random communities divided by their standard deviations. Standardized effect size is a useful measure if the test statistic (e.g., nestedness index, phylogenetic or functional diversity) in the random communities follows a symmetric distribution. In this paper, I would like to call attention to the fact that SES may give us misleading information if the distribution is asymmetric (skewed). For symmetric distribution median and mean values are equal (i.e., SES = 0 indicates p = 0.5). However, this condition does not hold for skewed distributions. For symmetric distributions departure from the mean shows the extremity of the value, regardless of the sign of departure, while in asymmetric distributions the same deviation can be highly probable and extremely improbable, depending on its sign. To avoid these problems, I recommend checking symmetry of null-distribution before calculating the SES value. If the distribution is skewed, I recommend either log-transformation of the test statistic, or using probit-transformed p-value as effect size measure.
Authors:Andreas Hahn, Rebecca Hinz, Thomas Meyer, Ulrike Loderstädt, Ottmar Herchenröder, Christian G. Meyer, Norbert Georg Schwarz, and Hagen Frickmann
Introduction: German sex workers have illegally established a prevention strategy, which consists of testing potential sexual partners with human immunodeficiency virus (HIV)-specific rapid diagnostic tests (RDTs) prior to engaging in unprotected sexual intercourse eventually performed in case of a negative test result. Based on a recently established modeling approach, the effectiveness of this strategy regarding the risk of HIV exposure was compared with protection provided by condom use.
Methods: Based on a literature search, the following assumptions were used for the calculations: an averaged 80% exposure risk reduction with a condom used during sexual intercourse, usage of a well-characterized 4th-generation HIV RDT, and a 10 day post-infection period without any measurable viral load in peripheral blood followed by a seroconversion period of about 3 weeks with 12.3% test sensitivity (antigen-specific) and only afterwards 97.3% (antibody-specific) test sensitivity.
Results: In most constellations, the HIV exposure risk in case of RDT-based prevention was lower than with condom use.
Conclusions: The RDT-based HIV exposure prevention as established by sex workers is effective in most situations. A notable weakness of the strategy is the RDTs' poor sensitivity in spite of a high transmission risk during the seroconversion stage.