Zell A. McGee

Tularemia: a 30-year experience with 88 cases.

Drawing upon our experience with 88 cases and a survey of the English literature, we reviewed the clinical, pathophysiological, and epidemiological aspects of tularemia. Tularemia can be thought of as two syndromes--ulceroglandular and typhoidal. This dichotomy simplifies earlier nomenclature and emphasizes the obscure typhoidal presentation. Clinical manifestations suggest that the two syndromes reflect differences in host response. In ulceroglandular tularemia the pathogen appears to be well contained by a vigorous inflammatory reaction. Pneumonia is less common and the patients prognosis is good. In typhoidal disease there are few localizing signs; pneumonia is more common; and the mortality without therapy is much higher, suggesting that the host response is somehow deficient. Francisella tularensis is an extremely virulent pathogen capable of initiating infection with as few as 10 organisms inoculated subcutaneously. During an incubation period of 3 to 6 days the host responds first with polymorphonuclear leukocytes and then macrophages. Granulocytes are unable to kill the pathogen without opsonizing antibody leaving cellular immunity to play the major role in host defense. One to 2 weeks after infection, a vigorous T-lymphocyte response can be detected in vitro with lymphocyte blast transformation assays and in vivo with an intradermal skin test, which, unfortunately, is not commercially available. Humoral immunity, often used as a diagnostic modality, appears 2 to 3 weeks into the illness. Cellular immunity is long-lasting, accounting for the common reoccurrence of localized disease upon repeated exposures to the pathogen. There are no symptoms that distinguish the ulceroglandular from the typhoidal syndrome. A pulse-temperature dissociation is seen in less than half of the patients. The location of ulcers and enlarged lymph nodes give a clue to the likely vector since lesions located on the upper extremities are more commonly associated with mammalian, and those of the head and neck and lower extremities with arthropod, vectors. Pharyngitis, pericarditis, and pneumonia can complicate both syndromes, although the latter is much more common in typhoidal disease. Hepatitis, usually of a mild degree, is common and occasionally erythema nodosum is seen. No specific laboratory tests characterize tularemia, and cultures of the pathogen are often difficult to obtain because of the special growth requirements of Francisella tularesis and the inability of many clinical laboratories to handle the dangerous pathogen.(ABSTRACT TRUNCATED AT 400 WORDS)

Local induction of tumor necrosis factor as a molecular mechanism of mucosal damage by gonococci

Tumor necrosis factor (TNF) is an endogenously produced cytokine that plays a critical role in mediating septic shock and multi-organ failure, but previous studies of the role TNF in disease have not examined its role in mucosal disease processes. In an experimental model of acute gonococcal salpingitis, gonococcal infection of human fallopian tube mucosa resulted in increased mucosal production of TNF. Recombinant human TNF-alpha damaged fallopian tube mucosa in a dose-response manner and produced epithelial damage with the same ultrastructural features as those observed in gonococcal infection. Blocking production of TNF during gonococcal infection diminished the extent of damage to fallopian tube mucosa. In addition to mediating systemic disease, such as septic shock, TNF is also produced locally, and can play a critical role in mediating mucosal disease processes, such as acute gonococcal salpingitis.

The induction of systemic and mucosal immune responses following the subcutaneous immunization of mature adult mice: characterization of the antibodies in mucosal secretions of animals immunized with antigen formulations containing a vitamin D3 adjuvant.

Systemic and mucosal immune responses were effectively induced following the subcutaneous administration of Haemophilus influenzae type b oligosaccharide conjugated to diphtheria toxoid vaccine in a formulation containing the active form of vitamin D3. IgA and IgG antibodies with specificity for both the protein and oligosaccharide components of the vaccine were detectable in mucosal secretions following immunization. The IgA and IgG mucosal antibodies were produced locally, and were functional as demonstrated by their diphtheria toxin neutralizing activity. Our data suggests that subcutaneous tissues can effectively serve as effective antigen presenting sites for both mucosal and systemic immune responses to antigens administered in combination with vitamin D3.

Gonococcal infection of human fallopian tube mucosa in organ culture: Relationship of mucosal tissue TNF-α concentration to sloughing of ciliated cells

BACKGROUND AND OBJECTIVES An experimental model consisting of gonococcal infection of human fallopian tube mucosa in organ culture has proven useful in studying the molecular pathogenesis of acute gonococcal salpingitis and postsalpingitis sequelae. Gonococcal infection of human fallopian tube mucosa in organ culture results in the sloughing of ciliated epithelial cells from the mucosa. This damage to the mucosa can be quantified on fallopian tube pieces by an assay of the percent of the periphery that has ciliary activity (PPCA) remaining at specific time points after infection. Although assay of the PPCA has been quite valuable, it is labor-intensive, somewhat subjective, and requires that the observers have training and experience. A more practical assay for genital mucosal damage is desirable for further investigations that employ the fallopian tube experimental model. Gonococcal infection of fallopian tube mucosa in organ culture also results in the production of easily quantified tumor necrosis factor-alpha (TNF-alpha) by the mucosa. Furthermore, treatment of the organ cultures with recombinant human TNF-alpha (rHuTNFalpha) alone also causes sloughing of ciliated cells from the mucosa. These findings strongly suggest that TNF-alpha is a mediator of the mucosal damage that attends gonococcal infection. GOALS OF THE STUDY To determine: (1) whether the PPCA values and the TNF-alpha concentrations in fallopian tube mucosal tissues correlate closely enough to allow prediction of the PPCA from a measurement of the mucosal tissue TNF-alpha concentration; and (2) whether the correlation of the TNF-alpha mucosal tissue concentration with the sloughing of ciliated cells (measured by the PPCA) supports the hypothesis that induction of TNF-alpha by gonococcal infection, with resultant sloughing of ciliated cells, is likely to be a major pathogenic mechanism of gonococcal salpingitis and might mediate postsalpingitis infertility and ectopic pregnancy. STUDY DESIGN A metaanalysis was performed on studies from three research groups (two laboratories in the United States and one in the United Kingdom, using identical techniques for quantifying the PPCA, TNF-alpha, or both. RESULTS There was a close and statistically significant correlation between the TNF-alpha mucosal tissue concentration and the proportion of ciliated cells lost from the mucosa as measured by the PPCA (r = 0.95, p < 0.001). Therefore, as the mucosal tissue concentration of endogenous TNF-alpha increased, the loss of ciliated cells from the epithelium increased proportionately. CONCLUSIONS During gonococcal infection of human fallopian tube mucosa in organ culture, the mucosal tissue concentration of TNF-alpha can be used to predict the PPCA, and therefore, the extent of mucosal damage. This finding should facilitate studies of the molecular pathogenesis of infectious diseases involving human genital mucosa. Further, the close correlation of mucosal TNF-alpha concentration with genital mucosal damage, evaluated by the PPCA, supports the hypothesis that induction of the proinflammatory cytokine, TNF-alpha, by gonococcal infection, with resultant inflammation and sloughing of ciliated cells, is an important pathogenic mechanism of gonococcal salpingitis and may mediate postsalpingitis infertility and ectopic pregnancy as well.

Evolution of antimicrobial resistance and nosocomial infection. Lessons from the Vanderbilt experience.

The development of antimicrobial resistance by bacteria has had profound effects of the clinical use of antibiotics, especially in hospital-acquired infections. In 1973, a large outbreak of nosocomial infections due to Serratia marcescens began at the Vanderbilt University medical complex, a major characteristic of which was high-level resistance to gentamicin and carbenicillin. Investigation of the outbreak and subsequent in vitro studies have shown that the evolution and epidemiology of this high-level resistance operated at three levels of organizations: (1) dissemination of individual strains, (2) dissemination of a plasmid among different strains and (3) movement of a discrete genetic element, or transposon, between plasmids. The investigations of this outbreak and other studies reviewed support the concept that resistant strains can evoke as a result of R-plasmid exchange within the hospital environment, providing an opportunity for control of this exchange can be interrupted.

The frequency of expression of pyelonephritis‐associated pili is under regulatory control

The Bscherfchia coli urinary tract Isolate C1212 contains two pyelonephritis‐associated pili (pap) DNA sequences designated here as pap‐17 and pap‐21. Each of these pap sequences encodes antigenically‐distinct pilin monomers, pllin‐17 and pilin‐21, respectively. Most individual strain C1212 cells isolated from a single bacterial colony expressed pilin‐21. Only a small fraction (5%) of strain C1212 cells expressed pilin‐17. Most of the latter population simultaneously expressed pilin‐21, but a low percentage of cells expressed pill composed of pilin‐17 alone. In contrast, almost every E. coli K‐12 cell containing multicopy pap‐17 expressed pilin‐17 at the ceil surface. These results Indicated that the regulation of pilin‐17 expression observed for strain C1212 was lost when pap‐17 was in the multicopy state. Transfer of pap‐17 to a single copy vector resulted in a pilin‐17 expression frequency lower than strain C1212 (1%). Using E. coli K‐12 containing single copy pap‐17, we found that the frequency of piiin‐17 expression increased about 15‐foid when pap‐21 was present in multiple copies in trans. Subcloning of pap‐21 showed that a 2.2 kilobase‐pair DNA sequence adjacent to, but not including, the pilin‐21 structural gene was sufficient for activation of pilin‐17 expression.

Symposium on nosocomial infections (part I)Evolution of antimicrobial resistance and nosocomial infection: Lessons from the vanderbilt experience☆

The development of antimicrobial resistance by bacteria has had profound effects of the clinical use of antibiotics, especially in hospital-acquired infections. In 1973, a large outbreak of nosocomial infections due to Serratia marcescens began at the Vanderbilt University medical complex, a major characteristic of which was high-level resistance to gentamicin and carbenicillin. Investigation of the outbreak and subsequent in vitro studies have shown that the evolution and epidemiology of this high-level resistance operated at three levels of organizations: (1) dissemination of individual strains, (2) dissemination of a plasmid among different strains and (3) movement of a discrete genetic element, or transposon, between plasmids. The investigations of this outbreak and other studies reviewed support the concept that resistant strains can evoke as a result of R-plasmid exchange within the hospital environment, providing an opportunity for control of this exchange can be interrupted.

Attachment of pathogenic Neisseria to human mucosal surfaces: Role in pathogenesis

Studies of the interaction betweenNeisseria gonorrhoeae and human fallopian tube mucosa in organ culture suggest that attachment of gonococci is important, not only to secure the organism in the host, but also to initiate the disease process. The steps observed in gonococcal infection of fallopian tube organ cultures are: 1) attachment of gonococci to microvilli of nonciliated cells; 2) release from gonococci of lipopolysaccharide and possibly other toxic moities to cause mucosa damage; 3) engulfment or phagocytosis of gonococci by nonciliated cells; 4) transport of phagocytic vacuoles containing gonococci to the base of the nonciliated cells; and 5) exocytosis of gonococci within phagocytic vacuoles into the subepithelial tissues.In vivo, these steps might result in extensive local disease (e. g. salpingitis) or in the invasion of blood vessels to cause disseminated disease. Preliminary studies of human nasopharyngeal tissue in organ culture infected withNeisseria meningitidis indicate that meningococci attach to microvilli of nonciliated cells and are phagocytized by these cells. Meningococci subsequently appear in subepithelial tissues, though the route they take is not yet certain. These observations suggest at least some of the ways in which attachment may play a role in disease caused byN. gonorrhoeae andN. meningitidis. Mechanisms to block this attachment may provide new approaches to the prevention of infections caused by the pathogenicNeisseria. Untersuchungen zur Wechselwirkung zwischenNeisseria gonorrhoeae und menschlicher Tubenschleimhaut in Organkultur lassen annehmen, daß das Anheften der Gonokokken den Erreger im Wirtsorganismus schützt und außerdem den Krankheitsprozeß in Gang setzt. In Organkulturen von Tubengewebe lassen sich folgende Schritte der Gonokokkeninfektion beobachten: 1) Die Gonokokken lagern sich an die Microvilli zilienfreier Zellen an; 2) Gonokokken setzen Lipopolysaccharide und möglicherweise auch andere toxische Verbindungen frei, die die Schleimhaut schädigen; 3) zilienfreie Zellen verschlingen oder phagozytieren Gonokokken; 4) phagozytäre Vakuolen mit Gonokokken werden an die Basis der zilienfreien Zellen transportiert; 5) Gonokokken in den phagozytären Vakuolen treten in das subepitheliale Gewebe aus.In vivo könnten diese Vorgänge zu einem ausgedehnten, lokalisierten Krankheitsprozeß (beispielsweise einer Salpingitis) führen oder zur Invasion in Blutgefäße mit disseminierter Erkrankung. Frühere Untersuchungen anN. meningitidis-infiziertem menschlichen Nasopharyngealgewebe zeigen, daß Meningokokken sich an Microvilli nichtzilientragender Zellen anheften und von diesen Zellen phagozytiert werden. Anschließend erscheinen Meningokokken im subepithelialen Gewebe; der Weg der Ausbreitung ist allerdings noch ungewiß. Aus diesen Beobachtungen lassen sich zumindest einige der Vorgänge ableiten, über die Adhäsion in der Pathogenese von Gonokokken- und Meningokokkenerkrankungen eine Rolle spielt. Mechanismen, die das Anheften der Bakterien verhindern, bieten möglicherweise neue Ansätze für die Prävention von Erkrankungen, die durch pathogene Neisserien verursacht werden.

Effect of human chorionic gonadotropin (hCG) on Neisseria gonorrhoeae invasion of and IgA secretion by human fallopian tube mucosa.

The possible effect of human chorionic gonadotropin (hCG) on the mucosal immune response and susceptibility of the fallopian tube mucosa to invasion by Neisseria gonorrhoeae (gonococci) was investigated in the fallopian tube organ culture (FTOC) model. Immunohistochemical and radioreceptor assay techniques showed specific high affinity binding of hCG in vitro to the apices of non-ciliated fallopian tube cells (Kd approximately 10(-9) M). Continuous exposure of the FTOC mucosa to hCG during infection with gonococci resulted in a marked increase (6- to 15-fold) in IgA secretion and significantly reduced gonococcal invasion (invasion score range 0.7 to 1.75) compared to infected control tissue which was not exposed to hCG (invasion score range 2.9 to 4.95, P less than or equal to 0.01). By contrast, exposure of the mucosa to hCG during the 24 h preceding gonococcal infection followed by the removal of hCG from the system at the time of infection resulted in enhanced gonococcal invasion (invasion score range 7.95 to 9.7, P less than 0.001). We conclude that hCG can modulate the mucosal immune response and susceptibility of fallopian tube epithelium to gonococcal invasion.

Gonococcal lipopolysaccharide: A toxin for human fallopian tube mucosa☆

Gonococci damaged the mucosa of human fallopian tubes in organ culture (FTOC), producing characteristic pathologic features. Filter-sterilized supernatant fluid from donor gonococcal-infected FTOC damaged recipient FTOC in a similar fashion. Gonococcal lipopolysaccharide (LPS) was detected in these toxic donor fluids in concentrations of 1.2 to 8.3 microgram/ml. Purified gonococcal LPS in concentrations as low as 0.015 microgram/ml produced damage equivalent to that caused by toxic donor fluid and was neutralized by polymyxin B. Such LPS-mediated damage to ciliated cells, if it occurs in gonococcal salpingitis, may impair mucociliary flow and predispose to ectopic pregnancy and recurrent ascending infection.