An epidemiological profile of brucellosis in Tabuk Province, Saudi Arabia

All 137 brucellosis cases occurring in Tabuk Province, Saudi Arabia in 1997 were studied retrospectively. Brucella agglutination titre of > or = 1/80, or rising titre plus history of typical signs and symptoms were considered evidence of infection. The incidence rate was 34/100,000, mean age 33.8 +/- 13.9 years (range: 3-72 years) and male:female ratio 1.8:1. There were 63.5% of cases rurally resident, 58.4% kept animals at home or elsewhere, 27.0% worked with animals and/or on farms, and 88.3% reported a history of raw milk ingestion. The most common infecting agents were Brucella melitensis, B. abortus and B. suis. Splenomegaly and hepatomegaly were detected in 25.5% and 22.6% of cases respectively.

A case of prosthetic mitral valve endocarditis caused by Brucella abortus

Endocarditis is a rare but serious complication of brucellosis. We report here a case of Brucella abortus endocarditis occurring on a prosthetic mitral valve. The diagnosis was established by positive serology, the presence of vegetation on the mitral prosthesis and isolation of B. abortus from the blood and valve cultures. The patient was successfully treated with combined medical and surgical therapy.

Brucellosis transmitted by bone marrow transplantation

We report a unique case of brucellosis transmitted by BMT. An 8-year-old boy with the diagnosis of Fanconi's anemia received an allogeneic BMT from his HLA-identical sibling. Routine culture from the infused marrow suspension grew Brucella abortus on day +4 post BMT. Spiking fevers occurred on days +2 and +16. The first febrile episode responded to broad-spectrum antibiotic therapy. However, the second episode did not. B. abortus was isolated from blood cultures taken during the second febrile episode. The Brucella agglutination titer was negative. Antibiotic therapy with oral doxycycline and i.v. gentamycin was successful with no recurrence of infection during 13 months of follow-up. The donor's blood culture was also positive for B. abortus and Brucella antibodies were detectable at 1:320 titer when he presented with fever and hepatosplenomegaly on day +32. We emphasize the need to consider brucellosis in patients undergoing BMT. We suggest that donor and recipient be evaluated for brucellosis especially in countries where the incidence of this infection is relatively high.

Brucella abortus infection acquired in microbiology laboratories

We report an outbreak of laboratory-acquired Brucella abortus infection originating in the accidental breakage of a centrifuge tube. A total of 12 laboratory workers were infected (attack rate of 31%), with an incubation time ranging from 6 weeks to 5 months. Antibody titers were evaluated weekly in all personnel exposed, allowing the diagnosis of the infection in most cases before the onset of clinical symptoms, so that specific therapy could be administrated.

Outer membrane proteins Omp10, Omp16, and Omp19 of Brucella spp. are lipoproteins

The deduced sequences of the Omp10, Omp16, and Omp19 outer membrane proteins of Brucella spp. contain a potential bacterial lipoprotein processing sequence. After extraction with Triton X-114, these three proteins partitioned into the detergent phase. Processing of the three proteins is inhibited by globomycin, a specific inhibitor of lipoprotein signal peptidase. The three proteins were radioimmunoprecipitated from [(3)H]palmitic acid-labeled Brucella abortus lysates with monoclonal antibodies. These results demonstrate that Omp10, Omp16, and Omp19 are lipoproteins.

Increased serum levels of interferon-gamma and interleukin-12 during human brucellosis

Brucellosis is a zoonotic disease that often becomes chronic with a high rate of recurrence. To understand the cytokines induced during this infection we determined the levels of interleukin (IL)-1beta, IL-2, IL-4, IL-8, IL-12, tumor necrosis factor-of (TNF-alpha) and interferon-gamma (IFN-gamma) in serum of patients with brucellosis and compared with those without brucellosis and controls. Control sera were taken from healthy persons residing in an area that was not endemic for brucellosis. The levels of IL-1, IL-2, IL-4, and TNF-alpha were not detectable in all the sera from patients. There was no difference in the level of IL-8 in patients with brucellosis and those without this disease. However, IL-8 was significantly higher in these two groups of patients compared with the controls. Significantly higher levels of IL-12 and IFN-alpha were found in the serum of patients with brucellosis compared with patients without brucellosis and controls. These data indicate that there is induction of Thl type cytokines during human brucellosis.

A case of cervical Brucella spondylitis with paravertebral abscess and neurological deficits

Spondylitis is one of the more frequent osteoarticular complications of Brucella infection, but cervical spine involvement is rare. We report here a case of cervical Brucella spondylitis with paravertebral anterior epidural abscess which resulted in neurological deficits. The diagnosis is based on clinical history supported by Brucella serology, radiological findings and histological evidence.

Evaluation of a fluorescence-polarization assay for the diagnosis of bovine brucellosis in México

A homogeneous fluorescence-polarization assay (FPA) was used for the serological diagnosis of bovine brucellosis in México. The assay uses O-polysaccharide prepared from Brucella abortus lipoplysaccharide (20-30 kDa) conjugated with fluorescein isothiocyanate as a tracer. To measure the fluorescence polarization, a FPM-1 fluorescence-polarization analyzer was used with the procedure described by Nielsen et al. (1996b). A cut-off value of 90 millipolarization (mP) units was used for testing 560 bovine sera from different areas of México. (305 positive sera and 255 negative sera according to the complement fixation test; CFT.) Some were tested with the Rose Bengal plate (RB) test (n = 490) and some with the rivanol-agglutination (RIV) test (n = 190). Sensitivities were 98.3%, 99.3% and 99.0%, and specificities were 68.8%, 55.4% and 96.9%, respectively, for RB, RIV and FPA. The FPA gave a kappa coefficient of agreement with respect to CFT of 0.96, while RB and RIV (relative to the CFT) gave coefficients of 0.70 and 0.61, respectively. Finally, ROC analysis suggested a cut-off value which agreed with the one recommended in the test procedure. We concluded that FPA is a suitable test to be used instead of the CFT in Mexican conditions.

[Splenic abscess caused by Brucella abortus]

A 23 year-old man with prolonged fever caused by Brucella abortus is reported. The uncommon feature of this case was the presence of a spleen abscess identified by computer tomography of the abdomen. Patient evolution was favorable after treatment with antibiotics, with complete regression of the lesions.

Synergistic action of streptomycin with other antibiotics of intracellular Brucella abortus in vitro

Richardson, Marvis (Michigan State University, East Lansing) and Jane N. Holt. Synergistic action of streptomycin with other antibiotics on intracellular Brucella abortus in vitro. J. Bacteriol. 84:638-646. 1962.-It has been found that streptomycin acts synergistically with penicillin and tetracycline to inhibit the growth of Brucella abortus within bovine cells cultured in vitro. Extracellular penicillin at 10 to 50 mug/ml was essentially bacteriostatic for intracellular brucellae. A combination of 5 to 50 mug/ml of streptomycin, which alone did not prevent the multiplication of intracellular brucellae, and 50 mug/ml of penicillin was bactericidal. Tetracycline at 0.5 to 1.0 mug/ml, which permitted growth or was bacteriostatic for brucellae within tissue cells, proved markedly bactericidal when combined with 10 mug/ml of streptomycin. Within certain limits, the synergistic effect of streptomycin and tetracycline did not appear to be a function of concentration. When the addition of streptomycin was delayed until 24 hr after the addition of tetracycline, the antibiotics acted synergistically on intracellular brucellae. To achieve intracellular synergism, five to ten times the effective extracellular concentration of streptomycin was required. Penicillin and tetracycline acted at the same concentration on extracellular and intracellular brucellae. These results suggest that tissue cell systems may prove useful for study of multiple drug therapy to be used in vivo against intracellular bacteria.

Rupture of bacteria by explosive decompression

Foster, John W. (University of Georgia, Athens), Robert M. Cowan, and Ted A. Maag. Rupture of bacteria by explosive decompression. J. Bacteriol. 83:330-334. 1962.-A device is described for instantaneously rupturing bacteria and other cells in a closed system under controlled conditions by explosive decompression. With this device, 31 to 59% of Serratia marcescens, ranging up to 20 mg (dry wt) of cells per ml, were ruptured after nitrogen saturation at 1740 psi. Under similar conditions, 10 to 25% of Brucella abortus and Staphylococcus aureus were ruptured. Rupture of these organisms produced readily separable cell walls. Centrifugation in linear glycerol gradients was applied to further separate cell walls from debris. Mycoplasma gallinarum, Leptospira pomona, and Eimeria tenella (avian coccidia) oöcysts were also broken up by the decompression chamber. Pressure and duration of saturation of cells with gas affected rupture efficiency. Within the limits of this study, concentration of organisms and volume of suspensions did not have a definite effect.

Effect of meprobamate on the multiplication of Brucella abortus in monocytes

Peritoneal mononuclear phagocytes (monocytes) obtained from guinea pigs that had been treated with meprobamate do not support, in vitro, the intracellular growth of smooth Brucella abortus that is characteristic of monocytes from untreated animals. This modification of intracellular events appears to be due to an indirect action of the drug, since meprobamate does not produce any effects following direct exposure of monocytes or bacteria to the drug in vitro. Furthermore, the brucellacidal activity of serum from animals exposed to meprobamate is not increased. An interaction between monocytes and a component in the serum of animals exposed to meprobamate is required for the altered intracellular events.

Metabolic characterization of the genus Brucella. I. Statistical evaluation of the oxidative rates by which type I of each species can be identified

Meyer, Margaret E. (University of California, Davis), and H. S. Cameron. Metabolic characterization of the genus Brucella. I. Statistical evaluation of the oxidative rates by which type I of each species can be identified. J. Bacteriol. 82:387-395. 1961.-The oxidative uptake rates on 11 amino acid and seven carbohydrate substrates were determined for 75 strains of brucellae that had been identified by the conventional determinative methods as Brucella melitensis type I, Brucella abortus type I, or Brucella suis type I. By calculating the standard deviation of the oxidative rates, it was demonstrated that a metabolic pattern that is characteristic and definitive for each of the species was formed by their differential oxidative utilization of substrate groups, and that qualitative as well as quantitative metabolic differences exist among the Brucella species. B. melitensis oxidized l-alanine, l-asparagine, and l-glutamic acid, but not l-arginine, dl-citrulline, l-lysine, dl-ornithine, l-arabinose, d-galactose, d-ribose, or d-xylose. B. abortus differed qualitatively from B. melitensis in that it oxidized the carbohydrate substrates. B. suis differed quantitatively from both of these species in its consistently low oxidative rates of l-alanine, l-asparagine, and l-glutamic acid, and its high rates of utilization of the carbohydrate substrates. It differed qualitatively in that it oxidized the four amino acid substrates that are components of the urea cycle.

Metabolic characterization of the genus Brucella. II. Oxidative metabolic patterns of the described biotypes

Meyer, Margaret E. (University of California, Davis), and H. S. Cameron. Metabolic characterization of the genus Brucella. II. Oxidative metabolic patterns of the described biotypes. J. Bacteriol. 82:396-400. 1961.-The oxidative metabolism of the biotypes of Brucella abortus and Brucella suis was compared to that of typical strains of these species. It was found that the biotypes of B. abortus display a metabolic pattern identical to that of B. abortus type I, irrespective of their differences in susceptibility to the bacteriostatic action of basic fuchsin and thionin. It was also found that a characteristic feature which distinguishes all of the biotypes of B. suis from the other species was their ability to oxidize l-arginine, dl-citrulline, and dl-ornithine. The three biotypes of B. suis can be differentiated from each other by discrete differences in their utilization of l-lysine and l-glutamic acid. Data on the oxidative rates obtained on eight amino acid and four carbohydrate substrates by 47 strains of the described biotypes are presented in support of these conclusions.

Mouse running activity is lowered by Brucella abortus treatment: a potential model to study chronic fatigue

Chronic fatigue syndrome, which can occur after acute infection and last for years, is characterized by severe and persistent fatigue. Others have reported decreases in mouse running activity following infection and have suggested this may provide an animal model for studying chronic fatigue. Voluntary running is a highly motivated activity in mice, which will often run 5-7 mi/day in our laboratory. Following 2 weeks of acclimation to running wheels with food and water available ad lib, female BALB/c mice received 0.2-mL tail vein injections of killed Brucella abortus (BA) or saline vehicle. Subsequently the effects on voluntary running and grooming behavior were determined. Injection of BA caused an immediate large decrease in running and a lack of grooming. Vehicle injections produced no changes in behavior. After the first several days of reduced running behavior, levels of running and grooming slowly returned back to normal over the next 2-4 weeks, with substantial individual differences in the rate of recovery. The pattern of running during recovery was intriguing in that BA mice first ran at normal levels just after the lights went out, but they stopped after only 1-2 h. As recovery proceeded, they gradually increased the duration of the running bout during the night. Because this model uses voluntary exertion and the ability to run for longer periods of time characterizes recovery, the model may be a good one for studying the biologic underpinnings of chronic fatigue.

Poor perinatal outcome associated with maternal Brucella abortus infection

BACKGROUND

Reports suggest that perinatal infection with Brucella abortus does not cause poor obstetric outcomes, because of protective mechanisms in the human, not seen in animal species.

CASE

We report a case of maternal brucellosis resulting in preterm labor, chorioamnionitis, placental abruption, and delivery of a live-born infant at 25 weeks' gestational age. Both maternal blood cultures and amniotic fluid cultures were positive for B abortus species, and delivery occurred despite aggressive antibiotic and tocolytic therapy.

CONCLUSION

Maternal infection with B abortus during pregnancy can lead to significant perinatal morbidity, casting doubt on reports that human pregnancy is resistant to such infection.

Interleukin 2 promoter/enhancer controlled expression of a synthetic cecropin-class lytic peptide in transgenic mice and subsequent resistance to Brucella abortus

The addition of an antimicrobial that can be synthesized by the mammalian immune system at the point of challenge may enhance disease resistance. A possible group of agents are cecropins, broad-spectrum antimicrobial peptides, which have been described and characterized. They are relatively non-toxic to normal cells from multicellular organisms but are toxic to a wide range of bacteria, protozoa and fungi, as well as infected and abnormal cells. Twenty-six lines of transgenic mice were produced by pronuclear injection of DNA consisting of the 5'-flanking region from -593 to +110 of the mouse interleukin 2 (IL-2) gene, Shiva 1a (a synthetic cecropinclass lytic peptide), and the SV40 polyadenylation/splice signal. A reverse-transcription PCR assay determined that two lines of transgenic mice were produced whose spleen-derived lymphocytes could be induced to transcribe and mature mRNA for Shiva 1a by exposure to 3.25 mg ml-1 of Con A. Two lines were challenged with an inoculation of 5 x 10(4) Brucella abortus strain 2308. After four weeks, there were significantly fewer B. abortus organisms in the spleens of transgenic mice than in non-transgenic control mice of the same strain (p < 0.05). Since the controlling regions of the IL-2 enhancer and the amino acid sequence of the signal peptide are highly conserved among several species, it is likely that this recombinant gene will function in other mammals.

Relationship of conserved residues in the IMP binding site to substrate recognition and catalysis in Escherichia coli adenylosuccinate synthetase

Gln34, Gln224, Leu228, and Ser240 are conserved residues in the vicinity of bound IMP in the crystal structure of Escherichia coli adenylosuccinate synthetase. Directed mutations were carried out, and wild-type and mutant enzymes were purified to homogeneity. Circular dichroism spectroscopy indicated no difference in secondary structure between the mutants and the wild-type enzyme in the absence of substrates. Mutants L228A and S240A exhibited modest changes in their initial rate kinetics relative to the wild-type enzyme, suggesting that neither Leu228 nor Ser240 play essential roles in substrate binding or catalysis. The mutants Q224M and Q224E exhibited no significant change in KmGTP and KmASP and modest changes in KmIMP relative to the wild-type enzyme. However, kcat decreased 13-fold for the Q224M mutant and 10(4)-fold for the Q224E mutant relative to the wild-type enzyme. Furthermore, the Q224E mutant showed an optimum pH at 6.2, which is 1.5 pH units lower than that of the wild-type enzyme. Tryptophan emission fluorescence spectra of Q224M, Q224E, and wild-type proteins under denaturing conditions indicate comparable stabilities. Mutant Q34E exhibits a 60-fold decrease in kcat compared with that of the wild-type enzyme, which is attributed to the disruption of the Gln34 to Gln224 hydrogen bond observed in crystal structures. Presented here is a mechanism for the synthetase, whereby Gln224 works in concert with Asp13 to stabilize the 6-oxyanion of IMP.