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PubMed2005

Immunohistochemical identification of Campylobacter fetus in natural cases of bovine and ovine abortions.

An immunohistochemistry (IHC) procedure for the detection of Campylobacter fetus antigens using an avidin-biotin complex technique was performed on formalin fixed bovine and ovine fetal tissues from 26 natural cases of Campylobacter spp. abortion (four ovine and 22 bovine). The species of Campylobacter isolated included C. fetus ssp. venerealis from 13 bovine fetuses, C. fetus ssp. fetus from two ovine and one bovine fetus, Campylobacter jejuni from seven bovine fetuses, Campylobacter lari from two ovine fetuses and an unspeciated Campylobacter species in one bovine fetus. Histologic lesions identified in the aborted fetuses included placentitis, serositis, pneumonia, gastroenteritis, hepatitis and encephalitis. Campylobacter fetus antigens were identified by IHC in 13 of 13 bovine fetuses from which C. fetus ssp. venerealis was isolated and in two of two ovine fetuses from which C. fetus ssp. fetus was isolated. The IHC stains were negative in tissues from seven bovine fetuses from which C. jejuni was isolated, one bovine fetus infected with C. fetus ssp. fetus, one bovine fetus infected with the unspeciated Campylobacter and two ovine fetuses infected with C. lari. In positive cases, the IHC stain most frequently identified bacteria in the lung and gastrointestinal tract. The C. fetus IHC procedure performed on formalin fixed tissues is a practical tool for the diagnosis of natural cases of ovine and bovine abortion caused by C. fetus.

Abortion, Veterinary↗
PubMed2006

Identification of Campylobacter fetus subspecies by phenotypic differentiation and PCR.

The species Campylobacter fetus is divided into the subspecies C. fetus subsp. venerealis and C. fetus subsp. fetus, which differ in their epidemiologies and clinical importance. The differences between these subspecies make accurate distinction between the two essential. First, the value of seven key tests for the traditional differentiation of C. fetus was investigated. Afterwards, the results of the phenotypic differentiation and PCR were compared to address the question of the reliability of this PCR assay. Altogether, 103 C. fetus isolates were investigated, including the type strains of C. fetus subsp. fetus and C. fetus subsp. venerealis. Depending on the result of the glycine tolerance test, the isolates could be separated into 81 C. fetus subsp. venerealis isolates (glycine intolerant) and 22 C. fetus subsp. fetus isolates (glycine tolerant). For all C. fetus subsp. venerealis strains tested, the results of the selenite reduction assay and sensitivity to metronidazole and cefoperazone completely agreed with the results of the glycine tolerance test (correspondence, 100%). Seventy-three C. fetus subsp. venerealis isolates did not grow at 42 degrees C (correspondence, 90.1%), but eight isolates showed a faintly discernible, flat, dark gray growth. For 22 C. fetus subsp. fetus isolates, the results of additional phenotypic tests only partly agreed with the results of the glycine tolerance test. For C. fetus subsp. fetus the results of the glycine tolerance test showed a relatively good correspondence with those of the selenite reduction assay (correspondence, 81.8%), assays for cefoperazone resistance (correspondence, 86.4%), and assays for growth at 42 degrees C (correspondence, 81.8%). The results of the glycine tolerance test and PCR completely agreed for the 103 C. fetus isolates tested. We conclude that at present the traditional phenotypic characterization of C. fetus subspecies under strongly defined conditions remains indispensable, but this PCR assay constitutes a valuable adjunctive technique for the confirmation of phenotypic results.

Animals↗
PubMed1990

Serogroups of Campylobacter fetus and Campylobacter jejuni isolated in cases of ovine abortion.

Of 38 aborted ovine fetuses from 23 sheep flocks 29 C. fetus subsp. fetus and 22 C. jejuni were isolated and examined biochemically and serologically for heat-stable antigens. Serologic examinations were carried out by passive haemagglutination test. In case of C. fetus subsp. fetus strains alkaline antigen extraction was used. Antisera to two serogroups of C. fetus and to Penner serotype reference strains 1 to 60 were produced in rabbits. Abortion was caused in 18 (78.3%) flocks by C. fetus subsp. fetus and in 5 (21.7%) flocks by C. jejuni. Six C. fetus subsp. fetus strains grew well at both 43 and 25 degrees C. With one exception all C. fetus subsp. fetus were resistant, whereas all 29 C. fetus subsp. venerealis strains were sensitive to 30 micrograms/ml cefoxitin and cefamandole. These two cephalosporins can be used to differentiate the two subspecies of C. fetus. Passive haemagglutination test using alkaline antigen extraction is a proper method for the examination of heat-stable antigens of both C. fetus subspecies. Out of 24 C. fetus subsp. fetus strains 13 belonged to serogroup A(01), and 11 to serogroup B(02). C. jejuni strains examined belonged to Penner serogroup 1 (6 strains), to serogroup 5 (4 strains) and to serogroup 8 (4 strains).

Abortion, Veterinary↗
PubMed2005

Clonal nature of Campylobacter fetus as defined by multilocus sequence typing.

Campylobacter fetus can be divided into the subspecies C. fetus subsp. fetus and C. fetus subsp. venerealis. C. fetus subsp. fetus causes sporadic infections in humans and abortion in cattle and sheep and has been isolated from a variety of sites in different hosts. C. fetus subsp. venerealis is host restricted, being isolated mainly from the genital tracts of cattle, and is the causative agent of bovine genital campylobacteriosis. Despite differences in niche preference, microbiological subspecies differentiation has proven difficult. Different typing methods divided C. fetus isolates into different subgroups, depending on the methods used. The relative value of these methods can be assessed by the evolutionary relationship of isolates belonging to the genus; therefore, we developed a multilocus sequence typing (MLST) scheme for C. fetus. This scheme was applied to 140 C. fetus isolates previously typed by amplified fragment length polymorphism (AFLP) analysis. A total of 14 different sequence types (STs) were identified, and these exhibited low levels of inter-ST genetic diversity, with only 22 variable sites in 3,312 nucleotides. These MLST data indicate that C. fetus is genetically homogeneous compared to the homogeneity of other Campylobacter species. The two C. fetus subspecies were extremely closely related genetically, but ST-4 was associated only with C. fetus subsp. venerealis, which represents a "bovine" clone. The C. fetus subsp. fetus isolates studied were more diverse in terms of their STs, and the STs correlated with epidemiological relationships. Congruence was observed among C. fetus subspecies, sap type, and ST; therefore, MLST confirms that mammalian C. fetus is genetically stable, probably as result of the introduction of a single ancestral clone into a mammalian niche.

Alleles↗
PubMed1987

Pathogenicity of a skin isolate of porcine parvovirus in swine fetuses.

The pathogenic properties of a skin isolate of porcine parvovirus (PPV), designated Kresse isolate, were compared with NADL-8 isolate, a prototype isolate of PPV, by in utero inoculation of mid-term and late-term gestation swine fetuses. Fetuses from pregnant sows of mid-gestation were inoculated with either NADL-8 or Kresse virus. Both isolates were highly pathogenic to mid-gestation fetuses. In contrast, dramatic differences in pathogenicity between these 2 isolates were observed in fetuses inoculated late in gestation. Such fetuses from each of 4 sows were inoculated with NADL-8 or Kresse virus isolate and sacrificed at 10, 18, 21, or 23 days postinoculation (PI). NADL-8-inoculated fetuses were grossly normal. The pathogenic effects of Kresse isolate were evident by gross pathology in fetuses collected at 18, 21, and 23 days PI, but not at 10 days PI. Hemagglutination (HA) and fluorescent antibody (FA) methods were used to identify virus in various tissues of late-gestation fetuses collected at 10 and 21 days PI. At 10 days PI, HA antigens were detected only in livers of NADL-8-inoculated fetuses, but in all tissues examined of Kresse-inoculated fetuses, including the brain. PPV specific fluorescence was demonstrated in tissues of fetuses inoculated with NADL-8 and Kresse virus. The major difference was that virus antigen was found in the brains of fetuses inoculated with Kresse virus, but not in NADL-8 infected fetuses. At 21 days PI, HA antigen was not detected in any of the tissues of fetuses inoculated with NADL-8 virus, with PPV specific fluorescence by FA being found only in the kidney. However, fetuses inoculated with Kresse virus displayed HA antigen in liver and PPV-specific fluorescence in all tissues tested including the brain. Both isolates induced similar antibody responses, 1:128 to 1:256 at 10 days and 1:512 to 1:1024 at 21 days PI. In addition, immunoglobulin G (IgG) deposits were demonstrated in kidneys and skin of fetuses inoculated with Kresse virus and IgM in brain, but not in tissues from fetuses inoculated with NADL-8 virus.

Animals↗
PubMed1997

The iliac angle as a sonographic marker for Down syndrome in second-trimester fetuses.

OBJECTIVE: To determine whether measurements of the iliac wing angle on sonograms of the second-trimester fetus can be used to detect fetuses at increased risk for Down syndrome. METHODS: All second-trimester Down syndrome fetuses karyotyped by amniocentesis over 5 years for whom adequate views of the iliac bones were available were reviewed retrospectively. The control group consisted of consecutive, normal second-trimester fetuses undergoing karyotyping during the same period. The angles between the iliac bones of the fetal pelves were measured on transverse sonograms, and the two groups were compared. A separate prospective evaluation of the ideal level for measurement of the iliac angle was made in two fetuses, one with and one without Down syndrome. RESULTS: We evaluated 38 Down syndrome and 46 control fetuses. The mean iliac-angle measurements differed significantly for the Down syndrome fetuses as compared with normal control fetuses: 78.8 degrees +/- standard deviation (SD) 18.5 and 66.9 degrees +/- SD 13.9, respectively. An iliac angle of at least 90 degrees was measured in 14 (36.8%) Down syndrome fetuses and in two (4.3%) control fetuses, also a significant difference. In a prospective pilot evaluation of two fetuses, we measured the largest iliac angle at the most cephalad level of the iliac bones, and the smallest angle was measured at the most caudad level. The iliac angle measurements for the fetus with Down syndrome ranged from 55 degrees to 100 degrees; for the normal fetus, the range was 52 degrees to 80 degrees. CONCLUSION: Although there is considerable overlap, the average iliac angle for fetuses with Down syndrome is significantly larger than that of normal fetuses. The angle measurement varies widely in any given fetus and is dependent on the level of the image. A prospective study is needed to evaluate the best level of angle measurement for the detection of fetuses with Down syndrome.

Adult↗
PubMed2002

Cardiac ventricular performance in the appropriate- for-gestational age and small-for-gestational age fetus: relation to regional cardiac non-uniformity and peripheral resistance.

OBJECTIVE: To investigate the relationship between parameters of diastolic function, loading conditions and remodeling of the left ventricle in the appropriate-for-gestational age and small-for-gestational age fetus. METHODS: Two-dimensional echocardiographic left ventricular images were digitized in 24 appropriate-for-gestational age and 14 small-for-gestational age fetuses. The maximal short axis and long axis were measured. The left ventricular contour was divided into 12 segments. The changes in whole left ventricular cavity area were calculated for ventricular global area change assessment. The coefficient of variation for segmental fractional area change was calculated for the evaluation of left ventricular regional wall motion non-uniformity. RESULTS: Mean left ventricular long axis/short axis ratio in the small-for-gestational age fetus (1.11 +/- 0.08) was smaller (P < 0.01) than in the appropriate-for-gestational age fetus (1.75 +/- 0.26). Mean fractional area change in the small-for-gestational age fetus was larger (P < 0.01) than in the appropriate-for-gestational age fetus (37.8 +/- 17.6% vs. 21.1 +/- 9.9%). Mean left ventricular global area change in the small-for-gestational age fetus was smaller (P < 0.05) than in the appropriate-for-gestational age fetus (53.2 +/- 7.4% vs. 61.5 +/- 10.3%). Mean ventricular isovolumic relaxation time in the appropriate-for-gestational age fetus was shorter (P = 0.03) than in the small-for-gestational age fetus (37 +/- 6 ms vs. 57 +/- 9 ms). Mean transmitral E-wave/A-wave ratio in the small-for-gestational age fetus was smaller (P < 0.01) than in the appropriate-for-gestational age fetus (0.69 +/- 0.08 vs. 0.80 +/- 0.08). A negative correlation (P < 0.05) was demonstrated between: (i) fractional area change and global area change in both small-for-gestational age (r = -0.62) and appropriate-for-gestational age fetuses (r = -0.58); (ii) umbilical artery systolic/diastolic ratio and transmitral E-wave/A-wave ratio in both appropriate-for-gestational age (r =-0.58) and small-for-gestational age (r = -0.60) fetuses. A positive correlation existed between fractional area change and isovolumic relaxation time in the small-for-gestational age fetus (r = +0.72; P < 0.01). CONCLUSIONS: The changes in ventricular shape, wall motion, spatial non-uniformity and diastolic function in the small-for-gestational age fetus could be considered as adaptive changes, known as ventricular remodeling. It is proposed that the leading cause of ventricular remodeling in the small-for-gestational age fetus is chronic pressure overload due to increased placental vascular resistance.

Female↗
PubMed1987

Differentiation of adipose tissue and muscle in hypophysectomized pig fetuses.

In the present study, fetuses were hypophysectomized (hypox) in utero on d 72 to 74 of gestation with an electrical cauterizing needle. One to six successfully hypox fetuses were removed on d 110 of gestation from each of five gilts. Subcutaneous adipose tissue samples and semitendinosus muscles were obtained from the hypox fetuses and an equal number of control fetuses. Body weights of control fetuses (n = 15; mean +/- SE, 1,195 +/- 33 g) were similar to weights of hypox fetuses (n = 15; 1,179 +/- 67 g). Fat cell size in the middle subcutaneous layer of adipose tissue was increased in hypox fetuses (P less than .01) compared with control fetuses. The number of obvious fat cell clusters (outer layer) in lipid stained sections was reduced (P less than .01) by 50% in hypox fetuses. Histochemical reactions for glucose-6-phosphate dehydrogenase, esterase and lipoprotein lipase (LPL) activities in middle layer cell clusters were considerably enhanced in sections from hypox fetuses compared with sections from controls. Quantitative analysis of percent light transmittance (Zeiss photometer) through LPL-stained cell clusters indicated an increase (P less than .001) in LPL staining in sections from hypox fetuses when compared with sections from control fetuses. Transverse muscle sections (cryostat) from hypox fetuses failed to show normal patterns (as seen in control muscles) of reactions for acid ATPase, malate dehydrogenase (NAD-dependent), NADH-TR and alpha-glycerol phosphate dehydrogenase (without NAD). The number of muscle fibers that were stained for these enzymes was greatly reduced in hypox fetuses compared with control fetuses. The number of lipid positive fibers was also reduced in hypox fetuses compared with control fetuses.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗
PubMed1984

The effects of pancreatectomy on the sheep fetus in utero.

The effects of the removal of the fetal pancreas on the fetal metabolite concentrations and body weight have been investigated in chronically catheterized sheep fetuses during the last third of gestation. Between 390 and 1175 mg of pancreatic tissue was removed under halothane anaesthesia from sixteen fetuses between 113 and 121 d of gestation (term = 147 +/- 2d). In six fetuses from which 928 +/- 58 mg of pancreas had been removed the insulin level (3.4 +/- 0.3 micro micron/ml, n = 6) was below or equal to the limit of sensitivity of the assay. As only very small pieces of pancreas, if any, could be found in these fetuses at delivery, removal of the pancreas was regarded as complete in these animals. Pancreatectomy was incomplete in five fetuses from which 659 +/- 62 mg of pancreas had been removed. Insulin was detected in the plasma of these fetuses although the mean concentration (9.1 +/- 0.7 micro micron./ml, n = 5) significantly less than that in sham-operated animals (P less than 0.01). Small fragments of pancreas (0-26 mg) containing endocrine cells were found in these fetuses at delivery. Fetuses from which less than 50% of the pancreas had been removed had plasma insulin and metabolite concentrations similar to those of the sham-operated fetuses. Significant amounts of histologically normal pancreas were found in these fetuses at delivery. The plasma concentrations of glucose, fructose and alpha-amino nitrogen were significantly greater in the incompletely and completely pancreatectomized fetuses than in the sham-operated animals (P less than 0.01). In addition, the completely pancreatectomized animals also had higher plasma levels of lactate and free fatty acids than the sham-operated fetuses (P less than 0.01). There were no significant differences in the urea concentrations between sham-operated and pancreatectomized fetuses, but the fetal to maternal concentration difference in arterial plasma urea was greatest in the completely pancreatectomized fetuses (P less than 0.05). The hypoinsulinaemic fetuses were significantly smaller in birth weight than the sham-operated animals (P less than 0.02). The results show that removal of about 70% of the fetal pancreas will produce hypoinsulinaemia in the fetus and confirm that the pancreas is essential for normal growth and development in utero.

Animals↗
PubMed2005

Genetic divergence of Campylobacter fetus strains of mammal and reptile origins.

Campylobacter fetus is a gram-negative bacterial pathogen of both humans and animals. Two subspecies have been identified, Campylobacter fetus subsp. fetus and Campylobacter fetus subsp. venerealis, and there are two serotypes, A and B. To further investigate the genetic diversity among C. fetus strains of different origins, subspecies, and serotypes, we performed multiple genetic analyses by utilizing random amplification of polymorphic DNA (RAPD), pulsed-field gel electrophoresis (PFGE), and DNA-DNA hybridization. All 10 primers used for the RAPD analyses can distinguish C. fetus strains of reptile and mammal origin, five can differentiate between C. fetus subsp. fetus and C. fetus subsp. venerealis strains, and four showed differences between type A and type B isolates from mammals. PFGE with SmaI and SalI digestion showed varied genome patterns among different C. fetus strains, but for mammalian C. fetus isolates, genome size was well conserved (mean, 1.52 +/- 0.06 Mb for SmaI and 1.52 +/- 0.05 Mb for SalI). DNA-DNA hybridization demonstrated substantial genomic-homology differences between strains of mammal and reptile origin. In total, these data suggest that C. fetus subsp fetus strains of reptile and mammal origin have genetic divergence more extensive than that between the two subspecies and that between the type A and type B strains. Combining these studies with sequence data, we conclude that there has been substantial genetic divergence between Campylobacter fetus of reptile and mammal origin. Diagnostic tools have been developed to differentiate among C. fetus isolates for taxonomic and epidemiologic uses.

Animals↗
PubMedDate not supplied

[Abnormal twin pregnancy--early resorption of a single fetus in a twin pregnancy pregnancy].

INTRODUCTION: Twin pregnancy presents a condition of development of two fetuses in the uterus and can be monozygotic (single ovum) and dizygotic (two ova). In case of fertilization and segmentation of one ovum monozygotic twins are produced, while in case of fertilization of two ova, which can originate from one or two Graff follicles, dizygotic twins are developed. The ratio of twin and single pregnancies is 1:89 (according to Hellin's law) (1). The incidence of twin and other multiple pregnancies is influenced by: race of parents, age and parity of mother, use of clomid and gonadotrophin to stimulate ovulation, discontinued use of contraceptive pills and certain seasons (exposure to sunlight) (1). Due to occurrence of numerous complications twin pregnancy and parturition are considered to be highly risky. This is supported by clinical data on more frequent spontaneous abortions--especially in monozygotic pregnancies, hypertension in pregnancy, hemorrhage of various etiologies, anemias, early rupture of amniotic membranes, hydramnios, premature deliveries, etc. Nowadays diagnosis of both twin and other multiple pregnancies in the early stage is required, in order to establish normal or pathological development of such pregnancies. As early as 6 gestation week in twin pregnancies it is possible to sonographically visualize two gestation sacs in the uterus, while in 7-8 gestation weeks it is possible to see two embryos with evidence of fetal heart rate. In early pregnancy a differentially-diagnosed uterus may be clinically enlarged due to: hydratidaform mole, uterine mioma or ovarian cyst. In later gestation confirmation of twin pregnancy is possible by clinical and sonographic examination and biochemical analyses (elevated values of HPL and -fetoprotein) and less frequently, by x-ray. Repeated sonographic examinations can reveal the following anomalies of twin pregnancies: one normal pregnancy with one sac containing no embryo, one sac containing no embryo and one sac with a dead fetus, fetuses without vitality in both gestation sacs, two ultrasound echoes from which only one normal fetus and one dead mummified fetus (fetus papiraceus) result within the uterus. One gestation sac may be resorbed during pregnancy, while the undamaged fetus continues to develop normally in the uterus. In certain cases the loss of one fetus is not accompanied by any clinical symptoms, and in others this can be accompanied by light hemorrhage. An initial twin pregnancy after the loss of one twin may end by a birth of one healthy infant. CASE REPORT: A patient aged 35 years, came for gynecological examination due to missed menstruation. Ananmesis showed that she had a nascent uterine myoma which was removed by myomectomy six months earlier, had one parturition four years earlier, and no abortions. The last menstrual period was on February 12, 1991. Clinical examination showed a somewhat larger uterus than would be normal for amenorrhea of 9-gestation week. By sonographic examination two regular gestation sacs were found in the uterus with fetal echoes present as well as heart rate in both fetuses (Figure 1). Embryo measurements were as follows: Fetus 1-CRL-22.5 mm, NEG-8 + 4, heart rate present. Fetus 2-CRL-23.6 mm, NEG-9, heart rate present (Figure 2). The patient was cautiously informed that two fetuses are visible in the uterus and that this is a sign of twin pregnancy, but for certain diagnosis a control examination was scheduled two weeks later. The sonographic examination after 14 days later showed discord in fetal growth (Figure 3). Embryo measurement in 11-gestation week rendered the following parameters: Fetus 1-CRL-22.8 mm, NEG 8 + 6, no heart rate registered (Figure 4), while the second fetus continued to develop and had the following characteristics: Fetus 2-CRL-50.5 mm, NEG 11 + 4, heart rate and fetal movement registered (Figure 5). During entire pregnancy the patient suffered no pain or any kind of hemorrhage. She took no drugs. (ABST

Adult↗
PubMed2005

Nonlinear analyses of heart rate variability in normal and growth-restricted fetuses.

BACKGROUND: Many studies on the physiology of the cardiovascular system reported that nonlinear chaotic dynamics may govern the generation of the heart rate signal. OBJECTIVE: To examine whether the heart rate dynamics of an intrauterine growth restricted (IUGR) fetus is different from a healthy normal fetus by nonlinear methods of time series analysis. DESIGN OF THE STUDY: One hundred nineteen fetal heart rate (FHR) recordings from healthy normal fetuses, and 69 recordings from IUGR fetuses were analyzed. Nonlinear analyses included attractor reconstruction, calculation of the largest Lyapunov exponents using the Wolf algorithm, and estimation of correlation dimension. The largest Lyapunov exponents from normal fetuses were checked by means of surrogate-data test. RESULTS: Abnormal FHR patterns of IUGR fetuses such as decreased variability and repetitive late decelerations presented a remarkably different structure in the reconstructed attractor. Surrogate data suggest that the FHR of healthy normal fetuses has unique nonlinear characteristics. The largest Lyapunov exponents were positive for all of 119 healthy normal fetuses, indicating that the FHR control system is sensitive to initial conditions. The values of IUGR fetuses were significantly lower than those of normal subjects. In normal fetuses, significant changes of correlation dimension according to gestational age were observed. In IUGR fetuses, however, such changes were not found. CONCLUSIONS: The heart rate dynamics of IUGR fetuses is less chaotic than that of normal fetuses. Decreased system complexity suggested by correlation dimension may limit the IUGR fetuses' ability to maintain cardiovascular integrity, and therefore, to adapt to the variety of internal and external cardiovascular stresses.

Female↗
PubMed2002

Campylobacter fetus adheres to and enters INT 407 cells.

Campylobacter fetus is a Gram-negative bacterial pathogen of humans and ungulates and is normally transmitted via ingestion of contaminated food or water with infection resulting in mild to severe enteritis. However, despite clinical evidence that C. fetus infection often involves transient bacteremic states from which systemic infection may develop and the frequent isolation of C. fetus from extra-intestinal sites, this organism displays very poor invasiveness in in vitro models of infection. In this study, immunofluorescence microscopy and gentamicin protection assays were used to investigate the ability of six clinical isolates and one reference strain of C. fetus to adhere to and invade the human intestinal epithelial cell line, INT 407. During an initial 4-h infection period, all C. fetus strains were detected intracellularly using both techniques, though adherence and internalization levels were very low when determined from gentamicin protection assays. Microscopy results indicated that during a 4-h infection period, four of the five clinical strains tested were adherent to 41.3-87.3% of INT 407 cells observed and that 25.2-34.6% of INT 407 cells contained intracellular C. fetus. The C. fetus reference strain displayed the lowest levels of adherence and internalization. A modified infection assay revealed that C. fetus adherence did not necessarily culminate in internalization. Despite the large percentage of INT 407 cells with adherent bacteria, the percentage of INT 407 cells with intracellular bacteria remained unchanged when incubation was extended from 4 h to 20 h. However, microscopy of INT 407 cells 24 h postinfection (p.i.) revealed that infected host cells contained clusters of densely packed C. fetus cells. Gentamicin protection assays revealed that intracellular C. fetus cells were not only viable 24 h p.i. but also that C. fetus had increased in number approximately three- to fourfold between 4 and 24 h p.i., indicative of intracellular replication. Investigation of the role of the host cell cytoskeleton revealed that pretreatment of host cells with cytochalasin D, colchicine, vinblastine, taxol, or dimethyl sulfoxide (DMSO) did not impact upon C. fetus adherence or internalization of INT 407 cells. Microscopy indicated neither rearrangement nor colocalization of either microtubules or microfilaments in INT 407 cells in response to C. fetus adherence or internalization. Together, these data indicate that clinical isolates of C. fetus are capable of adhering, entering, and surviving within the nonphagocytic epithelial cell line, INT 407.

Bacterial Adhesion↗