Variations in expression of carbon isotope fractionation of chlorinated ethenes during biologically enhanced PCE dissolution close to a source zone.

The stable carbon isotope values of tetrachloroethene (PCE) and its degradation products were monitored during studies of biologically enhanced dissolution of PCE dense nonaqueous phase liquid (DNAPL) to determine the effect of PCE dissolution on observed isotope values. The degradation of PCE was monitored in a 2-dimensional model aquifer and in a pilot test cell (PTC) at Dover Air Force Base, both with emplaced PCE DNAPL sources. Within the plume down gradient from the source, the isotopic fractionation of dissolved PCE and its degradation products were consistent with those observed in biodegradation laboratory studies. However, close to the source zone significant shifts in the isotope values of dissolved PCE were not observed in either the model aquifer or PTC due to the constant input of newly dissolved, non fractionated PCE, and the small isotopic fractionation associated with PCE reductive dechlorination by the mixed microbial culture used. Therefore the identification of reductive dechlorination in the presence of PCE DNAPL was based upon the appearance of daughter products and the isotope values of those daughter products. An isotope model was developed to simulate isotope values of PCE during the dissolution and degradation of PCE adjacent to a DNAPL source zone. With the exception of very high degradation rate constants (>1/day) stable carbon isotope values of PCE estimated by the model remained within error of the isotope value of the PCE DNAPL, consistent with measured isotope values in the model aquifer and in the PTC.

Pre-exposure anti-Campylobacter jejuni immunoglobulin a levels associated with reduced risk of Campylobacter diarrhea in adults traveling to Thailand.

Diarrhea history questionnaires were administered to 369 U.S. military volunteers before and after deployment to Thailand. Additionally, blood samples obtained from a subset of 221 volunteers 1-3 weeks previously and 3-4 weeks after their deployment were tested by enzyme-linked immunosorbent assay for immunoglobulin A to Campylobacter jejuni. Stool samples from personnel (including volunteers) contracting diarrhea in Thailand were cultured for enteric pathogens. Overall, 35.2% (130 of 369) of questionnaire respondents reported one or more diarrhea episodes during their trip. Volunteers with pretravel anti-C. jejuni reciprocal titers < or = 450 were 1.6 times as likely to have had diarrhea during their stay in Thailand compared with those with pretravel titers > 450 (39.7% versus 25.3%; P = 0.05). The symptomatic seroconversion, or attributable Campylobacter diarrhea attack rate, for the 1-month exercise was 12.7% (28 of 221). The symptomatic seroconversion rate in nonimmune (titer < or = 450) volunteers was 17.1%, whereas that in immune volunteers was only 4.0% (P = 0.002). Campylobacter jejuni or C. coli were recovered from 32.9% (56 of 170) of stool samples cultured and were the most commonly identified enteropathogens. Campylobacter diarrhea was associated with elevated temperatures, fecal red cells, and fecal white blood cells. The results of this study show that Campylobacter continues to represent a significant health threat to Western travelers to Thailand, but many of these travelers have preexisting Campylobacter immunity that protects them from clinically significant Campylobacter enteritis.

Posttreatment follow-up of Helicobacter pylori infection using a stool antigen immunoassay.

The Helicobacter pylori stool antigen enzyme immunoassay (HpSA) was evaluated during posttreatment follow-up of patients in a country with a very high prevalence of H. pylori infection. From among 273 dyspeptic individuals (18 to 55 years) initially recruited from a shantytown in Lima, Peru, 238 participants who met the inclusion criteria and were suspected to be H. pylori positive based on (14)C urea breath test (UBT) results underwent endoscopy. Participants with endoscopy-proven infections received standard eradication therapy and were monitored by UBT and HpSA at 1 month following treatment and at 3-month intervals for 9 months posttreatment. A second endoscopy was performed if UBT results showed evidence of treatment failure or H. pylori recurrence. Biopsy results were considered the "gold standard" in all analyses. Among patients who underwent endoscopy, HpSA had a pretreatment sensitivity of 93%. Two-hundred thirty patients completed the treatment regimen, of whom 201 (93%) were considered to have had successful treatment outcomes based on a negative follow-up UBT. Thirty-two patients with UBT-defined treatment failures or H. pylori recurrences at any point during the 9-month follow-up underwent a second endoscopy. In the posttreatment setting, HpSA had an overall sensitivity of 73% and a specificity of 67%. Agreement between UBT and HpSA diminished throughout the follow-up. Among 14 participants in whom HpSA remained positive at 1 month following treatment despite UBT evidence of treatment success, 12 (86%) became HpSA negative within 3 months posttreatment. Although this study confirmed the validity of the HpSA in the initial assessment of dyspeptic patients, the test demonstrated a reduced overall accuracy in the detection of treatment failures and H. pylori recurrences during 9 months of posttreatment follow-up. Furthermore, in some patients it may take up to 3 months after successful eradication for antigen shedding to diminish to levels within the negative HpSA range.

Enhanced in situ bioremediation of BTEX-contaminated groundwater by combined injection of nitrate and sulfate.

Enhancement of in situ anaerobic biodegradation of BTEX compounds was demonstrated at a petroleum-contaminated aquifer in Seal Beach, CA. Specifically, combined injection of nitrate and sulfate into the contaminated aquifer was used to accelerate BTEX removal as compared to remediation by natural attenuation. An array of multi-level sampling wells was used to monitor the evolution of the in situ spatial distributions of the electron acceptors and the BTEX compounds. Nitrate was utilized preferentially over sulfate and was completely consumed within a horizontal distance of 4-6 m from the injection well; sulfate reduction occurred in the region outside the denitrifying zone. By combining injection of both nitrate and sulfate, the total electron acceptor capacity was enhanced without violating practical considerations that limit the amount of nitrate or sulfate that can be added individually. Degradation of total xylene appears linked to sulfate utilization, indicating another advantage of combined injection versus injection of nitrate alone. Benzene degradation also appears to have been stimulated by the nitrate and sulfate injection close to the injection well but only toward the end of the 15-month demonstration. The results are consistent with the hypothesis that benzene can be biodegraded anaerobically after other preferentially degraded hydrocarbons have been removed.

In vitro antibiotic susceptibility of Neisseria gonorrhoeae in Jakarta, Indonesia.

Antibiotic susceptibilities were determined for 122 Neisseria gonorrheae isolates obtained from 400 sex workers in Jakarta, Indonesia, and susceptibilities to ciprofloxacin, cefuroxime, cefoxitin, cefotaxime, ceftriaxone, chloramphenicol, and spectinomycin were found. All isolates were resistant to tetracycline. A number of the isolates demonstrated decreased susceptibilities to erythromycin (MIC >/= 1.0 microg/ml), thiamphenicol (MIC >/= 1.0 microg/ml), kanamycin (MIC >/= 16.0 microg/ml), penicillin (MIC >/= 2.0 microg/ml), gentamicin (MIC >/= 16.0 microg/ml), and norfloxacin (MIC = 0.5 microg/ml). These data showed that certain antibiotics previously used in the treatment of gonorrhea are no longer effective.

Cholera in Indonesia in 1993-1999.

Cholera-specific surveillance in Indonesia was initiated to identify the introduction of the newly recognized Vibrio cholerae non-O1, O139 serotype. Findings from seven years (1993-1999) of surveillance efforts also yielded regional profiles of the importance of cholera in both epidemic and sporadic diarrheal disease occurrence throughout the archipelago. A two-fold surveillance strategy was pursued involving 1) outbreak investigations, and 2) hospital-based case recognition. Rectal swabs were transported to Jakarta for culture and isolates were characterized by serotypic identification. Outbreak findings showed that V. cholerae O1, Ogawa serotype, was the predominant etiology in all 17 instances of investigated epidemic transmission. Monitoring of eight hospitals representing seven provinces provided 6,882 specimens, of which 9% were culture positive for V. cholerae: 589 (9%) for O1 and 20 (< 1%) for non-O1 strains. Proportional representation of V. cholerae O1 among cases of sporadic diarrheal illness was variable, ranging from 13% in Jakarta to < 1% in Batam. Overall, 98% of V. cholerae O1 cases were the Ogawa serotype. There was no instance of non-O1, O139 serotype introduction in either epidemic or sporadic disease form. Anti-microbial drug susceptibility was consistently demonstrated, both temporally and spatially, except against colistin. Evidence is provided that epidemic and sporadic cholera occurrence in western Indonesia is associated with periods of low rainfall. Conversely, in the more eastern portion of the country, heavy rainfall may have contributed to epidemic cholera transmission.

Enhanced anaerobic bioremediation of groundwater contaminated by fuel hydrocarbons at Seal Beach, California.

Enhanced anaerobic biodegradation of groundwater contaminated by fuel hydrocarbons has been evaluated at a field experiment conducted at the Naval Weapons Station, Seal Beach, California. This experiment included the establishment of three different remediation zones in situ: one zone was augmented with sulfate, one was augmented with sulfate and nitrate, and the third was unaugmented. This enables a comparison of hydrocarbon biodegradation under sulfate-reducing, sequential denitrifying/sulfate-reducing, and methanogenic conditions, respectively. In general, the results from the field experiment are: (1) Certain fuel hydrocarbons were removed preferentially over others, but the order of preference is dependent upon the geochemical conditions; and (2) In the zones that were augmented with sulfate and/or nitrate, the added electron acceptors were consumed quickly, indicating that enhancement via electron acceptor injection accelerates the biodegradation process. More specifically, in the sulfate-reducing zone, sulfate was utilized with an apparent first-order rate coefficient of approximately 0.1 day(-1). In the combined denitrifying/sulfate-reducing zone, nitrate was utilized preferentially over sulfate, with an apparent first-order rate coefficient of 0.1-0.6 day(-1). However, the data suggest that slow sulfate utilization does occur in the presence of nitrate, i.e., the two processes are not strictly sequential. With regard to the aromatic BTEX hydrocarbons, toluene was preferentially removed under intrinsic conditions; biodegradation of benzene was slow if it occurred at all; augmentation with sulfate preferentially stimulated biodegradation of o-xylene; and ethylbenzene appeared recalcitrant under sulfate-reducing conditions but readily degradable under denitrifying conditions.

Expanded safety and immunogenicity of a bivalent, oral, attenuated cholera vaccine, CVD 103-HgR plus CVD 111, in United States military personnel stationed in Panama.

To provide optimum protection against classical and El Tor biotypes of Vibrio cholerae O1, a single-dose, oral cholera vaccine was developed by combining two live, attenuated vaccine strains, CVD 103-HgR (classical, Inaba) and CVD 111 (El Tor, Ogawa). The vaccines were formulated in a double-chamber sachet; one chamber contained lyophilized bacteria, and the other contained buffer. A total of 170 partially-immune American soldiers stationed in Panama received one of the following five formulations: (a) CVD 103-HgR at 10(8) CFU plus CVD 111 at 10(7) CFU, (b) CVD 103-HgR at 10(8) CFU plus CVD 111 at 10(6) CFU, (c) CVD 103-HgR alone at 10(8) CFU, (d) CVD 111 alone at 10(7) CFU, or (e) inactivated Escherichia coli placebo. Among those who received CVD 111 at the high or low dose either alone or in combination with CVD 103-HgR, 8 of 103 had diarrhea, defined as three or more liquid stools. None of the 32 volunteers who received CVD 103-HgR alone or the 35 placebo recipients had diarrhea. CVD 111 was detected in the stools of 46% of the 103 volunteers who received it. About 65% of all persons who received CVD 103-HgR either alone or in combination had a fourfold rise in Inaba vibriocidal titers. The postvaccination geometric mean titers were comparable among groups, ranging from 450 to 550. Ogawa vibriocidal titers were about twice as high in persons who received CVD 111 as in those who received CVD 103-HgR alone (600 versus 300). The addition of CVD 111 improved the overall seroconversion rate and doubled the serum Ogawa vibriocidal titers, suggesting that the combination of an El Tor and a classical cholera strain is desirable. While CVD 111 was previously found to be well tolerated in semiimmune Peruvians, the adverse effects observed in this study indicate that this strain requires further attenuation before it can be safely used in nonimmune populations.

Norwalk-like virus and bacterial pathogens associated with cases of gastroenteritis onboard a US Navy ship.

Acute gastroenteritis is a potential cause of substantial morbidity in U.S. military personnel during deployment. This study investigated the microbial causes of diarrhea in U.S. troops on exercises in Southeast Asia aboard the U.S.S. Germantown from March through May 1996. A total of 49 (7%) patients with diarrhea reported to sick call during a 3-month deployment involving 721 personnel. Diarrheal samples from 49 patients were subjected to bacterial and parasitologic examination, but sufficient samples from only 47 of 49 were available for analysis of the presence of Norwalk-like virus (NLV). Of the 49 diarrhea cases, 10 (20.4%) appeared to be due to bacterial etiology alone, 10 (20.4%) due to bacteria and the prototype Taunton agent (TNA), 11 (22.4%) due to TNA only, and 4 (8.0%) due to parasites. Norwalk-like virus RNA was present in 21 (45%) of 47 stool samples from the diarrhea cases, 10 with bacterial etiologies and 11 without bacterial or parasitic etiologies. No pathogen was detected in 14 (29%) of the cases. Four of the controls showed the presence of parasitic organisms. Of the 11 cases in which enterotoxigenic Escherichia coli was isolated, 8 were positive for colonization factor antigen (CFA/IV), and 3 were CFA-negative. The bacterial pathogens tested were all susceptible to gentamicin, and furadantin, but were resistant to ceftriaxone and norfloxacin, including 75% of the Campylobacter spp. These data support the view that the major cause of diarrhea for troops deployed in this geographic area is most likely NLVs.

Enterotoxigenic Escherichia coli diarrhea among young children in Jakarta, Indonesia.

The incidence of diarrhea and enterotoxigenic Escherichia coli (ETEC) infection was evaluated in children six months to five years of age from an urban community in Jakarta, Indonesia. From January through May 1994, 408 children were monitored in their homes for diarrheal disease. Thirty-six percent (148 of 408) of the study children had at least one episode of diarrhea during the study period. Twenty-nine (19.6%) of the 148 children with diarrhea had ETEC isolated from a rectal swab sample at least once during the surveillance period; five children had ETEC isolated from two distinct episodes of diarrhea, giving a total of 34 episodes of ETEC positive diarrhea in the study group. Ten of 34 episodes were associated with heat-labile toxin, 15 of 34 with heat-stable toxin, and seven of 34 with both toxins. The mean age of children with diarrhea (1.7 years), whether ETEC positive or negative, was significantly lower than those who did not have diarrhea (2.4 years) during the study period; 82% of the children with ETEC were less than two years of age. This study demonstrates a high incidence of ETEC diarrhea among young children in Jakarta, and suggests this site would be suitable for ETEC vaccine efficacy trials.

PIP: During a 4-month period in 1994, 408 children 6 months to 5 years of age (mean, 2.4 years) from a densely populated slum section (Kapuk) of West Jakarta, Indonesia, were monitored in their homes for diarrheal disease. Many homes in this community lack running water or toilet facilities. Overall, 148 (36%) of these children had at least one diarrhea episode during the study period. 29 children (19.6%) with diarrhea had enterotoxigenic Escherichia coli (ETEC) isolated from a rectal swab sample at least once during the surveillance period and five children had ETEC isolated from two distinct diarrhea episodes, for a total of 34 episodes of ETEC-positive diarrhea. 10 of the 34 episodes were associated with heat-labile toxin, 15 with heat-stable toxin, and 7 with both toxins. Annualized rates of diarrhea and ETEC infections were estimated at 2.2 and 0.3 per child, respectively. The rate of children with diarrhea declined steadily with increasing age: 52% at 6-11 months, 48% at 12-23 months, 28% at 24-35 months, 30% at 36-47 months, and 12% at 48-60 months. 82% of children with ETEC were under 2 years of age. The high incidence of ETEC diarrhea recorded in this study suggests the feasibility of ETEC vaccine efficacy trials in this population.

Coli surface antigens associated with enterotoxigenic Escherichia coli strains isolated from persons with traveler's diarrhea in Asia.

Enterotoxigenic Escherichia coli (ETEC) strains were isolated from travelers or military personnel who developed diarrhea after visiting Nepal or who were deployed to Thailand, Indonesia, or the Philippines. ETEC isolates were examined for colonization factor antigen (CFA). CFAs were identified on 59% (40 of 68) of the isolates examined. The lack of a detectable CFA on 41% (28 of 68) of the isolates is of concern for the development of an effective ETEC vaccine.

Distribution of colonization factor antigens among enterotoxigenic Escherichia coli strains isolated from patients with diarrhea in Nepal, Indonesia, Peru, and Thailand.

Samples (1,318) of enterotoxigenic Escherichia coli (ETEC) isolated in 1994-1995 from children with diarrhea from Nepal, Indonesia, Peru, and Thailand were examined for colonization factor antigen (CFA) and coli surface (CS) antigens. Fifty-five percent of 361 heat-labile and heat-stable (LT-ST), 14% of 620 LT-only, and 48% of 337 ST-only ETEC had CFA/CS antigens. LT-ST ETEC strains were predominantly in the CFA II group, and ST only strains were in the CFA IV group. Additional studies are needed to identify ETEC strains that do not have CFA/CS antigens.

Short report: impact of traveler's diarrhea on United States troops deployed to Thailand.

Among a United States military unit of 170 personnel deployed to Utapao, Thailand for a three-week training exercise, 40% experienced diarrheal disease, and 12% sought medical treatment for diarrhea. Most illness clustered within the first two weeks of arrival and individuals were ill an average of 3.6 days. Fifty-five percent of cases lost two days of work and 15% required treatment with intravenous fluids. Bacterial pathogens were recovered from 38% of 16 stools submitted, with Campylobacter jejuni the most common. Four (12.5%) of 32 persons who voluntarily submitted paired sera exhibited a four-fold increase in IgG antibody titer to C. jejuni. Traveler's diarrhea continues to be an important problem with a serious potential to impact the mission readiness of even small military units deployed overseas.

Enterotoxigenic Escherichia coli diarrhea in children less than five years of age in central Java.

A community-based prospective study was performed from December 1993 through March 31, 1994 in Indonesia in children less than five years of age. Enterotoxigenic Escherichia coli (ETEC) was identified in diarrheic stool by colony hybridization assay, using toxin probes, and this bacterium was isolated from 19% of 340 episodes of diarrhea. Sixty-one percent of ETEC produced heat-labile toxin (LT) only, 325 LT and heat-stable toxin (ST), and 75 ST only. The age-specific incidence rates of diarrhea among children 0-1 and 2-3 years of age were 77% and 61%, respectively, during the study period; ETEC was isolated from 26% of children 0-1 years of age versus 53% for children 2-3 years of age. As many as seven episodes of diarrhea were repeatedly experienced by a single child during the four-month study period; however, only two children had more than one episode of known ETEC-associated diarrheal disease during the period of observation.

Epidemiology of enterotoxigenic Escherichia coli-associated diarrheal disease occurring on board U.S. Navy ships visiting Asian ports.

Diarrhea represents a major health threat to U.S. military forces overseas, especially in developing countries. For military units, this illness can adversely affect combat readiness. USNAMRU-2 investigators joined several U.S. Navy ships to assess the epidemiology of diarrhea illness as a result of port visits to Asia. The primary goals were to enumerate episodes of diarrhea associated with port visits, identify epidemiologic factors leading to illness, and characterize the etiologic agents. Enterotoxigenic Escherichia coli (ETEC) was the most common organism isolated from patients presenting with diarrhea and represented 22% of diarrhea cases. Vomiting and abdominal pain differentiated ETEC from other causes of diarrhea.

Simple differentiation of Vibrio cholerae O139 from V. cholerae O1 and non-O1, non-O139 by modified CAMP test.

Strong positive CAMP reactions were demonstrated by 121 Vibrio cholerae O139 and 504 El Tor isolates, and weak positive CAMP reactions were shown by 235 non-O1, non O139 isolates when these isolates were tested by a modified CAMP technique. Thirty-five classical biotype V. cholerae O1 isolates included in the tests were all CAMP negative.

Inhibition of Growth and Aflatoxin Production of Aspergilli in Medium Containing Phosphates.

Mycelial growth and mycotoxin production of Aspergillus flavus and A. parasiticus were studied in Sabouraud dextrose agar containing pure or blended pyro-, poly- or meta-phosphates during 9 d of incubation at 30°C. Pure tetrasodium pyrophosphate (TSPP) and sodium polyphosphate, glassy (SPG, formerly hexametaphosphate), as well as a commercial phosphate blend and three combinations all containing various proportions of sodium acid pyrophosphate (SAPP), TSPP and SPG were tested. Inhibition of growth of aspergilli was observed in media containing 2.0% TSPP and 1.0 and 2.0% SPG and 2.0% of the commercial phosphate blend. Lower concentrations of single or blended phosphates allowed only limited, atypical mycelial growth. Sporulation was totally inhibited by 2.0% concentrations of single or blended phosphates, and so was production of aflatoxins B1 and G1. TSPP or SPG at 1.0% reduced (P<0.05) aflatoxin production from parts per million (controls) to parts per billion.

Inhibition of Mold Growth and Mycotoxin Production in High-Moisture Corn Treated with Phosphates.

Mold growth and mycotoxin production were studied in high-moisture (20%) corn treated with tetrasodium pyrophosphate (TSPP); acid and alkaline sodium polyphosphate, glassy (SPG), also known as sodium hexametaphosphate; sodium tripolyphosphate (STPP); and tricalcium phosphate. Six mold cultures belonging to the genera Aspergillus , Fusarium , and Penicillium were tested in corn varieties highly resistant or highly susceptible to mold infection in the field, and in a mixture of five other varieties of corn. The acidic SPG, as well as TSPP and STPP totally prevented or reduced mold growth when added in powder form to corn at 1.0% or 2.0% (w/w), regardless of corn variety and high moisture content. Phosphates afforded protection in whole and damaged kernels. Similar results were obtained with 2.0% acidic SPG and TSPP when added in spray form. Whenever mold growth occurred, treatment of corn with 1.0% or 2.0% (w/w) TSPP and acidic or alkaline SPG inhibited (P<0.01) aflatoxin production by aspergilli.