It has been known for almost a decade and a half that in trypanosomes all

Polymerase chain reaction (PCR)-based detection of New World Leishmania from different types of clinical specimens has been further streamlined for field use by simplifying sample preparation and modifying published protocols. A multiplex PCR reaction was developed that allows simultaneous detection of the Leishmania genus and identification of the L. braziliensis complex. For typing isolates in culture, we found that simply boiling diluted cultured strains was sufficient preparation for the PCR. We have demonstrated that Leishmania parasites can be reliably detected from boiled dermal scrapings, instead of the more invasive skin biopsies often used as PCR specimens. The PCR of dermal scrapings yielded a sensitivity of 100% and a specificity of 100%, as compared with microscopic examination. In a study population, PCR was more sensitive than classic diagnostic techniques. The PCR detection of Leishmania in biopsies and peripheral blood mononuclear cells (PBMCs) was investigated. Diluting crude extracts of skin biopsies was sufficient to eliminate sample inhibition yet maintain required sensitivity. Leishmania braziliensis was also detected by PCR in PBMCs of individuals with active cutaneous leishmaniasis. The simplifications described here significantly improve the feasibility of using the PCR in endemic countries as the primary method for detection and preliminary characterization of Leishmania in clinical specimens of cutaneous leishmaniasis.

A simplified polymerase chain reaction (PCR)-based assay was used for detection and typing of Leishmania parasites in clinical specimens from patients suspected of cutaneous leishmaniasis. Using cultures as the reference standard, our PCR detection method was more sensitive (92%) than classical diagnostic techniques, including microscopy (42% sensitivity), histologic staining (33%), and IgG enzyme-linked immunosorbent (20%). The PCR assay was also 100% specific. Parasites in both lesion biopsies and isolates cultured from lesion aspirates were identified as Leishmania braziliensis by PCR. In this study, we have demonstrated the suitability of simplified PCR assays for the simultaneous diagnosis and typing of parasites causing cutaneous leishmaniasis in a developing country where leishmaniasis is endemic.

Norepinephrine is a stress hormone that enhances bacterial growth. We examined the effects of a small inoculum on the norepinephrine-induced growth of species previously reported to be unaffected by norepinephrine. The results indicated that a reduced inoculum density is essential for observing norepinephrineinduced effects. Additional studies using serum-free media suggested that transferrin plays a role in norepinephrine-induced growth.Determining the direct effect of catecholamines on the in vitro growth response of bacteria is one interdisciplinary approach that has been utilized to increase our understanding of the role that stress hormones play in the establishment and progression of infection in a host (21). Although a great deal of evidence suggests that stress-induced neurohormones play a critical role in the outcome of infections (1,3,4,5,7,21,31), the mechanisms by which these hormones act in the host remain unclear. Studies with human and animal models have indicated that increased levels of stress hormones, including norepinephrine (NE), as well as other catecholamines, alter the immune response and physiology of the host (2). High circulatory levels of these hormones are detected in individuals exposed to a variety of physically and/or mentally stressful situations, including trauma, space flight, and sepsis (13,29,31,32). The increases not only may alter the immune function but also may contribute to host morbidity and increased risk of infection (1,7,34). In the current study we reexamined the in vitro growth responses of a variety of bacterial species that were previously tested and reported not to be enhanced by the addition of NE (6,8).The conditions employed in this study include a minimally nutritive low-iron medium previously shown to maintain bacteriostasis (21), a low initial inoculum density of bacteria (10 CFU/ml) in order to capture the lag phase of the bacterial growth curve typically observed in a bacteriostatic medium (21,26), and a concentration of NE (0.0001 M) (14, 15, 26) which corresponds to target tissue levels and not mere plasma spillover (16,18,20). These rigorous conditions better represent in vivo milieus and also allow more suitable evaluation of a growth enhancement effect without the camouflage of rapid bacterial growth encountered when rich medium and large inocula are employed.Using a lower initial inoculum density (approximately 10 CFU/ml), each species tested exhibited NE-induced enhancement of in vitro growth compared to nontreated controls. Cultures of Klebsiella pneumoniae, Pseudomonas aeruginosa, Enterobacter cloacae, Shigella sonnei, and Staphylococcus aureus grown in the presence of NE had shortened lag times and exhibited significant increases in bacterial counts (CFU/ml) at 18 and 24 h (Fig. 1) compared to the control. Moreover, for all of the gram-negative pathogens there were other times when there were significant increases in growth (Fig. 1A to D). S. aureus growth was only moderately affected by NE treatment, and there were significant differences in g...

It has been reported that spaceflight conditions alter the immune system and resistance to infection [Belay T, Aviles H, Vance M, Fountain K, and Sonnenfeld G. J Allergy Clin Immunol 170: 262-268, 2002; Hankins WR and Ziegelschmid JF. In: Biomedical Results of Apollo. Washington, DC: NASA, 1975, p. 43-81. (NASA Spec. Rep. SP-368)]. Ground-based models, including the hindlimb-unloading model, have become important tools for increasing understanding of how spaceflight conditions can influence physiology. The objective of the present study was to determine the effect of hindlimb unloading on the susceptibility of mice to Pseudomonas aeruginosa infection. Hindlimb-unloaded and control mice were subcutaneously infected with 1 LD50 of P. aeruginosa. Survival, bacterial organ load, and antibody and corticosterone levels were compared among the groups. Hindlimb unloading had detrimental effects for infected mice. Animals in the hindlimb-unloaded group, compared with controls, 1). showed significantly increased mortality and reduced time to death, 2). had increased levels of corticosterone, and 3). were much less able to clear bacteria from the organs. These results suggest that hindlimb unloading may induce the production of corticosterone, which may play a critical role in the modulation of the immune system leading to increased susceptibility to P. aeruginosa infection.