[Adherence of Acinetobacter baumannii to rat tracheal tissue]

BACKGROUND

Acinetobacter baumannii is an important nosocomial pathogen whose virulence factors have not been fully elucidated.

AIM

To study the adherence and hemagglutinating capacity of several biotypes of Acinetobacter baumannii.

MATERIAL AND METHODS

Thirty nine strains of Acinetobacter baumannii isolated from hospitalized patients were studied. The adherence of these strains to small pieces of rat tracheal tissue was studied. Additionally, their ability to hemagglutinate human erythrocytes and the effect of D-mannose and D-galactose on the adherence and hemagglutinating capacity was assessed. Transmission electron microscopy of strains was performed looking for the presence of fimbriae.

RESULTS

All strains exhibited adherence to tissues. All strains had also D-mannose and D-galactose resistant hemagglutinating ability. Fimbriae were found in Acinetobacter baumannii and E coil cells.

CONCLUSIONS

Adherence of Acinetobacter baumannii to rat tracheal tissue, apparently not related to the presence of fimbriae, may be a virulence mechanism of this bacterium.

Association of thin basement membrane nephropathy with hypercalciuria, hyperuricosuria and nephrolithiasis

BACKGROUND

Familial persistent microhematuria with normal renal function is the most common presentation of thin basement membrane nephropathy (TBMN). Gross hematuria episodes and loin pain attacks are other manifestations of the disease. On the other hand, it has been shown that hypercalciuria (HC) and hyperuricosuria (HU) can produce both gross or microscopic non-glomerular hematuria, in addition to their role in renal stone formation.

METHODS

We studied the prevalence of HC, HU and nephrolithiasis in a group of 27 biopsy-proven TBMN as well as in 19 non-biopsied first-degree relatives with persistent microhematuria and 25 first-degree relatives without microhematuria. A group of 27 patients with IgA nephropathy (IgAN) and persistent microhematuria, and another group of 20 healthy subjects without known renal diseases were selected as control groups.

RESULTS

Ten (37%) patients with TBMN and 8 (42%) relatives with microhematuria showed HC and/or HU at presentation; relatives without microhematuria, IgAN patients and normal controls showed a significantly lower prevalence of HC and HU. The prevalence of previous nephrolithiasis among TBMN patients (25%) was significantly higher than in IgAN patients (3%; P < 0.05). Family history of nephrolithiasis was recorded in 14 (51%) of the 27 TBMN families, in contrast with 2 of 27 (7%) with IgAN and 1 of 20 (5%) in normal controls (P < 0.05). The prevalence of nephrolithiasis, gross hematuria bouts and loin pain episodes among TBMN patients and microhematuric relatives showing HC and/or HU at presentation (44%, 44% and 27%, respectively) were significantly higher than those of TBMN patients and microhematuric relatives with normal calcium and uric acid urinary excretions (10%, 7% and 3%, respectively; P < 0.05). At the end of follow-up (8.8+/-4.1 years in TBMN patients and 9.1+/-4.2 years in relatives with microhematuria), all the cases maintained normal renal function.

CONCLUSIONS

We found a high prevalence of HC, HU, and nephrolithiasis among TBMN patients and relatives with microhematuria. Our study also shows a significant relationship between the presence of HC and/or HU and the prevalence of nephrolithiasis, gross hematuria bouts and loin pain episodes.

[Surface characteristics and antimicrobial sensitivity of clinical strains of Acinetobacter spp]

BACKGROUND

The treatment of nosocomial infections caused by Acinetobacter baumannii has been hindered by the easiness of this species to acquire antimicrobial resistance.

AIM

To study surface hydrophobicity, the presence of capsule and antimicrobial susceptibility of nosocomial Acinetobacter spp strains.

MATERIAL AND METHODS

Ninety four Acinetobacter spp strains isolated from a public hospital of Santiago, between July 1995 and April 1996, were studied.

RESULTS

Compared to Acinetobacter genospecies 3 isolates, A baumannii isolates exhibited greater antimicrobial resistance, was uniformly susceptible to imipenem and highly resistant to other antimicrobials of clinical use. Most strains of biotypes 8 and 9 were hydrophilic and encapsulated, whereas those of infrequent biotypes and of Acinetobacter genospecies 3 were, with few exceptions, hydrophobic and not encapsulated.

CONCLUSIONS

Capsule production might confer a greater virulence to Acinetobacter baumannii biotypes 8 and 9, and explain their higher prevalence in the studied hospital.

[Placental histopathology in premature rupture of membranes. Its relationship with microbiological findings, maternal, and neonatal outcome]

BACKGROUND

There is a close relationship between premature membrane rupture, bacterial infections and premature labor.

AIM

To study placental histological changes in patients with preterm membrane rupture. To establish a relationship between pathological findings, amniotic fluid and lower genital tract microbiological studies, maternal and neonatal outcome.

PATIENTS AND METHODS

Patients with premature membrane rupture of membranes between 24 and 34 weeks of gestation participated in this study. On admission, patients had no evidence of clinical chorioamnionitis, labor or fetal distress. Microbiological studies of the amniotic fluid and cervicovaginal secretions were performed and the placenta was sent for pathological study.

RESULTS

Seventy one placentas were available for the study. The main pathological findings were acute chorioamnionitis in 58%, trophoblastic proliferation in 38%, funisitis in 37%, villitis in 16%, fetal vascular lesions in 14% and no findings in 17%. Microbial invasion of amniotic cavity was present in 89% of acute chorioamnionitis. Sixty one percent of trophoblastic proliferation and all fetal vascular lesions were associated with negative amniotic and cervical cultures. Newborns with acute funisitis had a higher frequency of neonatal death (29%), severe asphyxia (42%) and neonatal infections (29%).

CONCLUSIONS

Acute chorioamnionitis is the most frequent finding in patients with preterm membrane rupture and microbial invasion of amniotic cavity. In the absence of intra amniotic infection, proliferation of the trophoblast and the presence of fetal vascular lesions predominate. Acute funisitis is strongly associated with adverse fetal outcome.

Prevalence and genotypes of GB virus C/hepatitis G virus (GBV-C/HGV) and hepatitis C virus among patients infected with human immunodeficiency virus: evidence of GBV-C/HGV sexual transmission

The development of new antiretroviral agents may improve survival of HIV-infected individuals, and therefore chronic viral hepatitis may become more relevant in these patients. The presence of GBV-C/HGV and hepatitis C virus (HCV) RNA were investigated by reverse transcriptase-nested polymerase chain reaction in plasma from 168 Spanish HIV-infected patients belonging to four different risk groups: intravenous drug users (IVDUs), hemophiliacs, homosexuals, and heterosexuals. GBV-C/HGV-RNA and HCV-RNA were detected in 18% and 43% of the patients, respectively. The prevalence of current infection with these viruses was notably high, 19% for GBV-C/HGV and 69% for HCV, among individuals with parenteral risk of infection (intravenous drug abusers and hemophiliacs), but sexual transmission with GBV-C/HGV was also suggested because 16.5% of patients with sexual risk, either homosexual or heterosexual, had GBV-C/HGV-RNA in plasma. Although investigation of GBV-C/HGV-RNA possibly underestimates the actual prevalence of infection with GBV-C/HGV, the above data suggest that sexual contact may play a relevant role in the spread of this virus. Phylogenetic analysis showed no evidence for clustering of NS3 sequences into different genotypes or subtypes of GBV-C/HGV.

Familial mediterranean fever and acute myocardial infarction secondary to coronary vasculitis

AIMS

We report a case study to elucidate the pathogenesis of polyarteritis nodosa (PAN) type vasculitis, a rare complication of familial mediterranean fever (FMF).

METHODS AND RESULTS

A woman with amyloidosis complicating FMF underwent a cadaveric renal transplantation and 5 years later suffered an acute myocardial infarction secondary to an isolated coronary vasculitis.

CONCLUSIONS

The histopathological findings of the vasculitis were not in keeping with PAN. We postulated that the pathogenesis of vasculitis in FMF is different from that of the classic PAN and might be similar to the mechanism of the serosal inflammation.

Evolution subverting essentiality: dispensability of the cell attachment Arg-Gly-Asp motif in multiply passaged foot-and-mouth disease virus

Aphthoviruses use a conserved Arg-Gly-Asp triplet for attachment to host cells and this motif is believed to be essential for virus viability. Here we report that this triplet-which is also a widespread motif involved in cell-to-cell adhesion-can become dispensable upon short-term evolution of the virus harboring it. Foot-and-mouth disease virus (FMDV), which was multiply passaged in cell culture, showed an altered repertoire of antigenic variants resistant to a neutralizing monoclonal antibody. The altered repertoire includes variants with substitutions at the Arg-Gly-Asp motif. Mutants lacking this sequence replicated normally in cell culture and were indistinguishable from the parental virus. Studies with individual FMDV clones indicate that amino acid replacements on the capsid surface located around the loop harboring the Arg-Gly-Asp triplet may mediate in the dispensability of this motif. The results show that FMDV quasispecies evolving in a constant biological environment have the capability of rendering totally dispensable a receptor recognition motif previously invariant, and to ensure an alternative pathway for normal viral replication. Thus, variability of highly conserved motifs, even those that viruses have adapted from functional cellular motifs, can contribute to phenotypic flexibility of RNA viruses in nature.

Differential restrictions on antigenic variation among antigenic sites of foot-and-mouth disease virus in the absence of antibody selection

Clonal populations of foot-and-mouth disease virus have been serially passaged in cell culture to analyse variation in the absence of immune selection at different antigenic sites of the virus. Mutant frequencies at the RNA regions encoding two independent antigenic sites (sites C and D) were more than twentyfold lower than for antigenic site A (the G-H loop of VP1). Correspondingly, fixation of amino acid substitutions was very restricted in sites C and D. In spite of such a restriction, neutralization assays using fractionated anti-virus polyclonal antibodies has provided direct evidence of significant antigenic variation in the absence of immune selection at sites unrelated to site A. It is proposed that the degree of tolerance to acceptance of amino acid replacements may modulate the variation at different antigenic epitopes of the same virus.

Relationship between viral genotype and viral load in patients with chronic hepatitis C

To determine the distribution of hepatitis C virus (HCV) genotypes and to related genotype to viral load, genotyping and quantification of viral RNA were carried out in 35 patients with chronic hepatitis C. Subtype 1a was most prevalent (43%), followed by subtypes 1b (23%) and 3a (14%). Mean viral load (log HCV-RNA copies/ml) for subtypes 1b, 1a and 3a was 7.1 +/- 1, 5.6 +/- 1.1 and 4.1 +/- 2.4, respectively. The presence of immunoglobulin M was related to the duration of hepatitis and genotype 1 to a more severe hepatic injury and higher viral load. Differences observed in viral load for a single HCV subtype justify the need to quantify HCV-RNA prior to establishing antiviral therapy.

Synthesis of Enantiopure syn-beta-Amino Alcohols. A Simple Case of Chelation-Controlled Additions of Diethylzinc to alpha-(Dibenzylamino) Aldehydes

Enantiomerically pure syn-2-amino alcohols 6 are prepared by addition of diethylzinc to chiral alpha-(dibenzylamino) aldehydes 4. The addition is highly stereoselective, leading to syn-2-(dibenzylamino) alcohols 5 with excellent diastereomeric excesses (76-98%). Debenzylation of 5 by hydrogenolysis on Pearlman's catalyst yields quantitatively the amino alcohols 6.

Evaluation of CHROMagar Candida medium for the isolation and presumptive identification of species of Candida of clinical importance

CHROMagar candida is a new differential culture medium that allows the isolation and presumptive identification of species of yeast of clinical importance. We tested 618 strains of yeast, including 128 direct isolates from clinical specimens. After two days of incubation at 37 degrees C, 339 of 341 Candida albicans, 98 of 99 Candida glabrata, all the Candida tropicalis, and all the Candida krusei were identified correctly. The sensitivity and specificity in these cases were both superior to 99%. Easy to prepare, with low cost, CHROMagar Candida proves to be a useful medium for the identification of species of yeast that are isolated with greater frequency in clinical material and for the identification of mixed cultures.

[Tuberculin reactivity in the elderly. Comparison of PPD-RT23 and PPD-CT68]

BACKGROUND

Tuberculin reactivity varies on the basis of the PPD lot and the population studied.

AIMS

To compare tuberculin reactivity in the elderly following successive applications of PPD from 2 different lots.

POPULATION

Elderly nursing-home residents, from the province of Guadalajara, Spain.

METHODS

The elderly were randomly selected and administered with a first Mantoux intradermoreaction of 2 UT of PPD-RT23 or 2 UT of PPD-CT68. The study was performed in a scaled basis, eliminating the reactors (transversal induration > or = 5 mm at 72 h). The non reactors were restudied with a second and third test in alternative arms at a 7-day interval with the same lot and initial dosis of PPD. At one year the scaled study was repeated with 2 UT of PPD-CT68.

RESULTS

Eight hundred and thirty elderly persons (79 +/- 9 years) were studied, with 410 receiving PPD-RT23 and 420 receiving PPD-CT68. No differences were observed in the percentage of initial reactors (31% vs 29%; p = 0.26) or in the booster reactors (23% vs 20%; p = 0.16). The PPD-RT23 was found to trigger more intensive reactions than the PPD-CT68 leading to a greater frequency of indurations > 14 mm. After one year, the percentage of stable reactions was similar in both groups (50.5% vs 49.5%; NS).

CONCLUSIONS

1) In elderly nursing-home residents 2 UT of PPD-RT23 and 2 UT of PPD-CT68 showed similar results in regard to the number of reactors and the frequency of booster reactions. 2) The proportion of intense reactions was greater with 2 UT of PPD-RT23 than with 2 UT of PPD-CT68. 3) The stability of the reactions at one year was independent of the lot used in the first phase.

Reverse transcriptase and substrate dependence of the RNA hypermutagenesis reaction

G-->A hypermutation is a remarkable phenomenon resulting from retroviral reverse transcription in the presence of highly biased dNTP concentrations. Of the three reverse transcriptases (RTases) available, those of human immunodeficiency virus type 1 (HIV-1), avian myeloblastosis virus (AMV) and Moloney murine leukemia virus (MoMLV), the HIV-1 enzyme showed the greatest sensitivity to biased [dCTP]/[dTTP] ratios. The HIV-1 RTase was able to discriminate between dUTP, dITP and the four DNA precursors and was insensitive to pH. There was little preference for nucleotide contexts. A few exceptionally modified sequences were found presumably resulting from G-->A hypermutation and multiple strand transfer. This particular predilection of the HIV-1 and, by extrapolation, the lentiviral RTases towards G-->A hypermutation suggests that the phenomenon may have contributed to the remarkably elevated A content of these retroviral genomes.

Pharmacokinetics and residues of enrofloxacin in chickens

The pharmacokinetic properties of enrofloxacin were determined in broiler chickens after single IV and orally administered doses of 10 mg/kg of body weight. After IV and oral administrations, the plasma concentration-time graph was characteristic of a two-compartment open model. The elimination half-life and the mean +/- SEM residence time of enrofloxacin for plasma were 10.29 +/- 0.45 and 9.65 +/- 0.48 hours, respectively, after IV administration and 14.23 +/- 0.46 and 15.30 +/- 0.53 hours, respectively, after oral administration. After single oral administration, enrofloxacin was absorbed slowly, with time to reach maximal plasma concentration of 1.64 +/- 0.04 hours. Maximal plasma concentration was 2.44 +/- 0.06 micrograms/ml. Oral bioavailability was found to be 64.0 +/- 0.2%. Statistically significant differences between the 2 routes of administration were found for the pharmacokinetic variables--half-lives of the distribution and elimination phase and apparent volume of distribution and volume of distribution at steady state. In chickens, enrofloxacin was extensively metabolized into ciprofloxacin. Residues of enrofloxacin and the major metabolite ciprofloxacin in fat, kidney, liver, lungs, muscles, and skin were measured in chickens that received an orally administered dose of 10 mg/kg once daily for 4 days. The results indicate that enrofloxacin and ciprofloxacin residues were cleared slowly. Mean muscle, liver, and kidney concentrations of the metabolite ciprofloxacin ranging between 0.020 and 0.075 micrograms/g persisted on day 12 in chickens after dosing. However, at the time of slaughter (12 days), enrofloxacin residues were only detected in liver and mean +/- SEM concentration was 0.025 +/- 0.003 micrograms/g.

[Postoperative infection and anesthesia: analysis of various risk factors]

OBJECTIVES

To study the possible relation between anesthetic techniques and other perioperative circumstances and factors and the presentation of infections after surgery.

PATIENTS AND METHODS

We studied 22 patients who suffered infections after surgery and 54 who did not, analyzing the anesthetic technique used as well as other data on age, sex, concomitant disease, toxic habits, practice of invasive procedures, duration and nature of the surgical procedure and the use of antibiotic prophylaxis. Multivariate analysis (logistical regression) was performed in order to identify independent risk factors.

RESULTS

None of the anesthetic techniques studied was associated with greater frequency of postoperative infection. Infected patients were significantly older than uninfected patients (75 +/- 9 years versus 61 +/- 18 years). Likewise the number of infections was higher among ASA III and IV (n = 20) patients than among ASA I and II (n = 2). The duration of surgery for infected patients was 4.15 +/- 2.12 hours whereas it was 2.87 +/- 1.86 hours (p < 0.001) for uninfected patients. Placement of a urinary catheter, repeated surgery, diabetes and blood transfusion all signified greater risk of infection, as did prophylaxis with second and third generation cephalosporins (OR = 12.5; 95% CI = 1.8-85.6) or tobramycin (OR = 66.4; 95% CI = 3.5-1,270).

CONCLUSION

The risk of postoperative infection increases with age and poor physical status of patients (ASA III and IV), with diabetes, repeated surgery, transfusion of blood products and prophylaxis with third generation cephalosporins and tobramycin.

[Characterization of a multiresistant strain of Vibrio cholerae O1, isolated from a case of cholera in Chile]

This report characterizes a multiresistant Vibrio Cholerae O1 strain, isolated from a patient with cholera, and investigates the mechanism of resistance. The analyzed strain was resistant to tetracycline, chloramphenicol and trimethoprim-sulfamethoxazole. The resistance was mediated by a 101 megadalton plasmid that was transferred to the resultant of a conjugation assay between the multiresistant V. Cholerae strain and E. coli C-600 used as receptor strain, that acquired the triple resistance of the parental strain. The resistant V. cholerae strain had a Ogawa serotype, El Tor biotype and toxigenic capacity, demonstrated by ELISA and latex agglutination techniques. The biochemical features of the strain were identical to those of susceptible strains, except for the resistance to 10 and 150 ug o 129 vibriostatic factor. The emergence of plasmid mediated resistance to drugs of choice in the treatment of cholera must alert Chilean and Latin American health authorities, considering the cholera will continue affecting the region.

Purification and characterization of eukaryotic polypeptide chain initiation factor 4F from Drosophila melanogaster embryos

The eukaryotic polypeptide chain initiation factor 4F (eIF-4F), purified by m7GTP-Sepharose chromatography from whole extracts of Drosophila melanogaster embryos, consists of two subunits, the previously identified eIF-4E (35 kDa) (Maroto, F. G., and Sierra, J. M. (1989) Mol. Cell. Biol. 9, 2181-2190) and another of 200 kDa. Both subunits cosedimented through a sucrose density gradient containing 0.5 M KCl. In contrast to rabbit reticulocyte eIF-4F, we did not find any RNA-dependent ATPase associated with the Drosophila factor. As shown previously for eIF-4E, the p200 subunit was also required for the translation of endogenous mRNAs in cell-free systems from Drosophila embryos. Only the eIF-4E subunit was able to cross-link to the m7G cap structure. However, an efficient cross-linking of the p200 subunit to an uncapped mRNA was observed. Both subunits were phosphorylated in vitro by protein kinase C from rat brain. As an extension of our previous results (Zapata, J. M., Maroto, F. G., and Sierra, J. M. (1991) J. Biol. Chem. 266, 16007-16014) we found that the translation of the heat shock mRNAs was independent of both of the eIF-4F subunits.