Diagnostic utility of postmortem blood cultures

The autopsy is receiving renewed emphasis as a tool for quality assurance in clinical medicine. Postmortem blood cultures frequently are taken during the autopsy but are costly and of unclear diagnostic utility. To assess whether postmortem blood cultures contribute any useful information not already known from antemortem blood cultures, we compared positive postmortem blood cultures taken in 111 autopsies with the results of antemortem blood cultures. Of these, 60 (54%) of 111 had positive postmortem blood cultures despite a cause of death not related to an infectious cause. Of the 111 patients, 54 (49%) had antemortem blood cultures drawn in the 7 days before death, of which 34 (63%) of 54 were negative and 20 (37%) of 54 were positive. Of the 20 patients with true antemortem bacteremia/fungemia, seven (35%) had postmortem blood cultures that yielded the same organism, 10 (50%) yielded multiple organisms that were considered to be contaminants, and three (15%) yielded different organisms. These latter three cultures yielded microorganisms that were related to the patients' illness but did not provide additional information not already known from antemortem blood cultures or the patients' clinical or autopsy findings. Of the 91 patients who had no, negative, or contaminated antemortem blood cultures, 69 (76%) had postmortem blood cultures that yielded contaminants and 22 (24%) yielded microorganisms that were indeterminate as a cause of sepsis and, therefore, did not yield new or useful information. In summary, results of postmortem blood cultures rarely, if ever, provide information that is not already known, can be interpreted, provide new insights into pathophysiology, or detect errors in therapy.

Rationale for selective use of anaerobic blood cultures

Because of the declining frequency of anaerobic bacteremia, routinely using half the collected blood volume for anaerobic culture has been challenged. There is no data indicating whether more clinically relevant isolates would be recovered if all or most of the given blood sample were cultured aerobically. In this two-part study, we reviewed cases of anaerobic bacteremia to determine what proportion occurred in situations when anaerobes would be expected and then estimated the yield of different culture approaches by reanalyzing the data from a large prospective clinical blood culture study. The records of 61 patients who had an anaerobic isolate (excluding Propionibacterium species) recovered only from an anaerobic bottle were examined to define clinical settings in which such isolates occur. Fifty-six (92%) patients had clinically important isolates, and the source of infection was obvious at the time of culture in 47 of the 56 (84%). Of 56 patients, 36 (64%) had abdominal signs and symptoms, including 12 with recent abdominal surgery. Of nine patients without an obvious source of infection, six were on high-dose steroids. Relative yields were compared for (i) one aerobic bottle and one anaerobic bottle (5 ml to each) for all blood cultures, (ii) two aerobic bottles (5 ml to each), or (iii) two aerobic bottles plus an extra anaerobic bottle (only for clinically suspected anaerobic sepsis) (5 ml to each). The third approach had the highest yield (475 isolates), because the routine use of two aerobic bottles recovered more Candida spp., members of the family Enterobacteriaceae, and nonfermenters than did the first approach (448 isolates) (P < 0.02), and clinically directed culturing for anaerobes would recover anaerobes missed with the second approach (458 isolates). Our data suggest that the use of two aerobic bottles with selective culturing for anaerobes could increase the number of clinically relevant isolates by at least 6% compared with the current practice of inoculating an aerobic bottle and an anaerobic bottle with equal volumes of blood.

Field studies on the epidemiology of Venezuelan hemorrhagic fever: implication of the cotton rat Sigmodon alstoni as the probable rodent reservoir

During February 1992, field studies on the epidemiology of Venezuelan hemorrhagic fever (VHF) were carried out in a rural area of Portuguesa State in central Venezuela. The objective of this work was to determine the prevalence of infection with Guanarito virus, the etiologic agent of VHF, among wild rodents and humans living within an endemic focus of the disease. A total of 234 rodents, representing nine different species, were collected and their spleens were cultured for virus. Thirty-one Guanarito virus isolates were made from two rodent species: 19 from 40 Sigmodon alstoni and 12 from 106 Zygodontomys brevicauda. Guanarito virus antibody rates among these two species were 5.1% and 15.0%, respectively. Nine of the 12 Z. brevicauda that yielded virus from their spleens also had Guanarito virus antibodies in their sera. In contrast, none of the 19 Guanarito virus-positive S. alstoni had antibodies to the virus. These data suggest that S. alstoni usually develops a persistent nonimmunizing infection with Guanarito virus, while Z. brevicauda develops an immunizing infection. Based on knowledge of the behavior of other human pathogenic arenaviruses, these results imply that S. alstoni is the principal rodent reservoir of Guanarito virus in nature. To determine the prevalence of Guanarito virus infection among humans in the same region, 195 people living near one of the rodent collecting sites were bled and their sera were tested for antibodies to the virus. Five individuals (2.6%) had Guanarito virus antibodies; all were adults, and two had been diagnosed previously as having VHF.(ABSTRACT TRUNCATED AT 250 WORDS)

Association of ticks (Acari: Ixodoidea) with rodent burrows in northern Senegal

Four species of ticks were retrieved from burrows of 64 multimammate rats, Mastomys erythroleucus (Temminck), 55-gerbils, Taterillus gracilis (Thomas) or T. pygargus (Cuvier), 13 Nile rats, Arvicanthis niloticus (DeMarest), and five Geoffroy's ground squirrels, Xerus erythropus (Geoffroy) from May 1987 through August 1988 at two study sites in northern Senegal. Ornithodoros sonrai Sautet & Witkowski were recovered from 95% (74/78) of burrows near Bandia and 6% (4/66) of burrows near Yonofere. Eight Hyalomma truncatum Koch, four Rhipicephalus guilhoni Morel & Vassiliades, and one R. sulcatus Neumann were recovered from 144 rodent burrows (nine tick-positive burrows) from both locations. No seasonal trend of tick abundance or activity was noted, nor was any pattern of burrow preference by ticks detected. Rodent burrows in either location appeared to be little used by ixodid ticks.

Fecal leukocytes in stool specimens submitted for Clostridium difficile toxin assay

To determine their diagnostic utility, fecal leukocytes were sought by methylene blue stain in 502 consecutive stool specimens submitted for Clostridium difficile toxin assay. In addition, the stability of fecal leukocytes was assessed by daily examination of 23 stool specimens stored at 4 degrees C and room temperature. The sensitivity, specificity, and positive and negative predictive values of fecal leukocytes in predicting C. difficile toxin assay results were 28%, 92%, 27%, and 93%, respectively. At 4 degrees C, fecal leukocytes retained morphology for a minimum of 3 days. Leukocytes survived as long in stool specimens containing either C. difficile toxin or an enteric pathogen as they did in stool specimens with neither finding. We conclude that testing stool specimens for fecal leukocytes is not useful for predicting the presence of C. difficile toxin, because 72% of stool specimens positive for C. difficile toxin are negative for fecal leukocytes despite their stability.

Controlled comparison of the BACTEC high-blood-volume fungal medium, BACTEC Plus 26 aerobic blood culture bottle, and 10-milliliter isolator blood culture system for detection of fungemia and bacteremia

The BACTEC high-blood-volume fungal medium (HBV-FM) (Becton Dickinson Diagnostic Instrument Systems, Sparks, Md.) was compared with the Isolator (IS) tube and the BACTEC Plus 26 (BP26) blood culture bottle for the ability to recover fungi from the blood of adult patients suspected of having fungemia. A total of 6,836 blood culture sets that fulfilled criteria for inclusion in the study were received. Three separate comparisons were performed: 4,907 HBV-FM versus IS, 4,886 BP26 versus HBV-FM, and 4,949 BP26 versus IS. For the HBV-FM versus IS comparison, 218 isolates were recovered: 125 (57.3%) were bacteria and 93 (42.7%) were fungi. HBV-FM was comparable to IS for recovery of yeasts, but IS was superior for recovery of Histoplasma capsulatum (25 versus 0 isolates recovered [P < 0.001]). Growth of Torulopsis glabrata was detected earlier (P < 0.05) in HBV-FM bottles. For the BP26 versus HBV-FM comparison, 229 isolates were recovered: 161 (70.3%) were bacteria, and 68 (29.7%) were fungi. HBV-FM was superior for recovery of T. glabrata (P < 0.025) and all fungi combined (P < 0.025). There were no statistically significant differences in the speed of detection of microbial growth. For the BP26 versus IS comparison, 251 isolates were recovered: 165 (65.7%) were bacteria, and 86 (34.2%) were fungi. IS was superior for recovery of H. capsulatum (P < 0.001), T. glabrata (P < 0.05), and fungi other than H. capsulatum (P < 0.025). BP26 was superior for recovery of all bacteria combined (P < 0.001) and viridans group streptococci (P < 0.01). Growth of T. glabrata (P < 0.05) was detected earlier in IS tubes. Growth of Staphylococcus aureus (P < 0.01), viridans group streptococci (P < 0.01), Pseudomonas aeruginosa (P < 0.05), and all microorganisms combined (P < 0.05) was detected earlier in BP26 bottles. For yeast, 57 of 59 (96.6%), 79 of 80 (98.7%), and 64 of 67(95.5%) were recovered from BP26 bottles, HBV-FM bottles, and IS tubes, respectively, by day 14; for H. capsulatum, 14 of 36 (38%) isolates were recovered from IS tubes by day 14. Mean times of recovery were similar for BACTEC bottles and IS. We conclude that (i) for recovery of fungi from blood cultures, HBV-FM is equivalent to IS (with the exception of H. capsulatum); (ii) for recovery of bacteria, BP26 is superior to IS; (iii) BP26 bottles are inferior to both HBV-FM bottles and IS tubes for recovery of T. glabrata; and (iv) HBV-FM bottles must be paired with another blood culture bottle or system to optimize detection of bacteremia.

Experimental vector incompetence of a soft tick, Ornithodoros sonrai (Acari: Argasidae), for Crimean-Congo hemorrhagic fever virus

Adults and nymphs of a soft tick, Ornithodoros sonrai Sautet & Witkowski, were allowed to feed on suckling mice that had been experimentally infected with Crimean-Congo hemorrhagic fever (CCHF) virus (IbAr 10200 strain). The mean viral titer of mouse blood at the time of tick feeding was 10(3.2) plaque-forming units (PFU) per ml. Samples of ticks were assayed on 12 occasions between days 0 and 31 after the viremic blood meal. Mean CCHF viral titers were 10(2.1) PFU per tick immediately after the viremic meal but declined to 10(1.2) PFU per tick after 2 d, and no virus was detected beyond 8 d. The percentage of ticks with detectable virus was 92% (22/24) immediately after the viremic meal, but then declined to 20% (2/10) after 4 d and to 0% (0/44) after 11 or more days. Ticks were allowed to feed on sets of three naive suckling mice on days 0, 2, 5, 8, 11, 14, 21, and 28 after the viremic blood meal, but CCHF viral transmission did not occur. Similarly, no transovarial transmission of virus from CCHF virus-exposed O. sonrai to their progeny was observed. These results strongly indicate that O. sonrai is not a vector of CCHF virus.

Temperature- and humidity-dependent longevity of unfed adult Hyalomma truncatum (Acari: Ixodidae)

The survival of unfed adult Hyalomma truncatum Koch held under different regimes of constant temperature (5, 17, 24, and 30 degrees C) and relative humidity (10, 50, and 80%) was monitored during > 1 yr. Longevity of this medically important African tick was shortest at the highest temperature and lowest relative humidity (100% dead at week 25). Conversely, H. truncatum lived longest at lower temperatures and higher relative humidity (< 100% dead at week 64). The combined effects of temperature and humidity, measured as vapor pressure deficit, were strongly related to survival of these ticks. The survival of males and females was similar and was independent of the weight of ticks. These findings have implications for the maintenance and study of laboratory colonies of H. truncatum and for the development of tick control strategies to reduce vectorial capacity.

Dispersal of the sand fly Lutzomyia longipalpis (Diptera: Psychodidae) at an endemic focus of visceral leishmaniasis in Colombia

Mark-release-recapture studies were carried out during 1990-1991 in El Callejón, Colombia, an endemic focus of American visceral leishmaniasis, to study the longevity, dispersal, and flight range of the principal vector, Lutzomyia longipalpis Lutz & Neiva. Several groups of wild-caught (n = 1,539) and laboratory-reared F1 (n = 2,208) sand flies were marked with fluorescent dusts and released. Recaptures at daytime resting sites, on animal bait, and in CDC light traps were made for 20 d following each release. From 2 to 9% of L. longipalpis were recaptured, a rate which differed between the sexes (7.7% male, 1.5% female). Overall, 49% of the L. longipalpis were recaptured between 0 and 50 m, 48% within 100 and 300 m, and nearly 3% at > or = 0.5 km from the release site. Sex differences in recapture site, distance flown, and direction were observed. Our results indicate that the dispersal behavior of peridomestic populations of L. longipalpis compares more closely with that of Old World sand fly species from similar habitats than to the sylvan Neotropical phlebotomines.

Intestinal parasites and HIV infection in Tanzanian children with chronic diarrhea

OBJECTIVE

To determine whether specific intestinal parasites are associated with HIV infection in Tanzanian children with chronic diarrhea.

DESIGN

A prospective, cross-sectional study.

SETTING

Muhimbili University College of Health Sciences, Dar es Salaam, Tanzania.

SUBJECTS

All children aged 15 months to 5 years admitted with chronic diarrhea, and age-matched controls.

METHODS

Standardized history, physical examination, HIV serology, and stool parasitology were evaluated for all subjects. We compared three groups: HIV-infected and non-HIV-infected children with chronic diarrhea and controls without diarrhea.

MAIN OUTCOME MEASURES

Fecal parasites and nutritional status.

RESULTS

Chronic diarrhea accounted for one-quarter of all cases of diarrheal disease in the defined age range, and children with chronic diarrhea were severely malnourished. Forty per cent of subjects with chronic diarrhea were HIV-seropositive. Although intestinal parasites were detected in approximately 50% of all three groups, diarrheagenic parasites were detected in up to 40% of children with chronic diarrhea. Blastocystis hominis was detected only in HIV-infected patients.

CONCLUSIONS

HIV infection was common in children with chronic diarrhea, and parasitic agents of diarrhea may be important in children with chronic diarrhea both with and without HIV infection in this setting. B. hominis was more frequent in HIV-infected children. The immunocompromising effects of severe malnutrition may have diminished the difference between HIV-infected and non-HIV-infected children.

Reduced abundance of immature Ixodes dammini (Acari: Ixodidae) following incremental removal of deer

The abundance of immature Ixodes dammini Spielman, Clifford, Piesman & Corwin was monitored for 9 yr (1983-1991) before and during the controlled, limited hunting of white-tailed deer, Odocoileus virginianus (Zimmerman), at a coastal Massachusetts site. Deer abundance was reduced from an estimated 350 during 1985 to approximately 60 during 1991. Although annual fluctuations were large, mean larval I. dammini abundance declined from 20.8 per white-footed mouse, Peromyscus leucopus (Rafinesque), during 1983-1986 before deer reduction to 10.3 per mouse following deer reduction (1987-1991). Similarly, mean nymphal I. dammini abundance declined from 2.7 per mouse before intervention to 1.6 per mouse after intervention. Immature I. dammini population fluctuations were not associated with those of P. leucopus. The total population of larvae infesting P. leucopus declined from 3,596 ticks before intervention to 1,535 ticks after intervention. Concurrently, the total nymphal population declined from 417 ticks before intervention to 187 ticks after intervention. The number of feeding adult female I. dammini on deer increased as deer density decreased.

Recovery of clinically important microorganisms from the BacT/Alert blood culture system does not require testing for seven days

Recently, we published a comparison of the BacT/Alert blood culture system with the BACTEC 660/730 nonradiometric blood culture system using blood inocula of 5 ml per bottle. By reanalyzing data collected during that study, we found that, for true-positive isolates causing bacteremia or fungemia, 363 (97.6%) of 376 and 341 (97.7%) of 349 isolates were recovered by the end of day 5 of testing, and 364 (97.9%) of 376 and 343 (98.3%) of 349 isolates were recovered by the end of day 6 of testing for aerobic and anaerobic bottles, respectively. Most isolates recovered on days 6 (24 of 27) and 7 (20 of 25) of testing were either contaminants or indeterminate as a cause of sepsis. When used as recommended by the manufacturer, only six (1.3%) of 464 clinically important isolates recovered on test days 6-7 would have gone undetected had testing been limited to 5 days and four (0.9%) of 464 had testing been limited to 6 days. We conclude that BacT/Alert bottles can be tested for as few as 5 days and then discarded with minimal loss of true-positive isolates and maximal reduction of contaminants.

Application of rejection criteria for stool ovum and parasite examinations

We retrospectively determined the yield of 2,015 stool ovum and parasite (O&P) examinations performed over an 11-month period. Two aspects were evaluated: the yield of positive results from multiple specimens per patient versus the result of a single examination, and the yield of positive results from stools submitted after 3 days of hospitalization. There were 131 (6.7%) positive O&P examinations from 75 patients: for 35 patients the single examination was positive; for 18, two of two examinations were positive; and for 15, three of three examinations were positive. The remaining seven patients had at least one negative examination in a series, but pathogenic intestinal parasites were detected in only three of these patients. Seventeen patients with positive O&P examinations were inpatients: seven of nine patients examined for O&P within 3 days of admission had stool specimens that contained recognized pathogens, in contrast to only two of eight patients examined after 3 days of hospitalization. After reviewing the data and informing hospital clinics, wards, and physicians, we instituted the following policy for screening stool specimens submitted for O&P examination. Only one O&P examination was performed for each outpatient visit and for inpatients hospitalized for 3 days or less, and examinations were not performed on stools submitted after 3 days of hospitalization unless the clinician arranged for the examination on the basis of clinical need. Over the 6-month follow-up period, 29.9% of O&P requests were rejected, 22% for patients in hospital for longer than 3 days and 7.9% for multiple O&P requests. Of 265 initially rejected specimens, 22 (8.3%) were examined after the referring physician contacted the laboratory. None of these specimens was positive. We conclude that eliminating O&P examinations of patients hospitalized for more than 3 days and initially performing only one examination per patient significantly reduces the number of examinations performed and reduces laboratory charges without adversely affecting patient care.

Vegetation structure influences the burden of immature Ixodes dammini on its main host, Peromyscus leucopus

To determine whether the relative abundance of immature Ixodes dammini (the vector of Lyme disease and human babesiosis) is related to habitat structure, we examined tick burdens on their main host, the white-footed mouse (Peromyscus leucopus), in 4 structurally diverse sites on Great Island, Massachusetts, USA. Vegetation structure at each site was quantified with respect to 25 habitat variables. Principal components analysis was used to reduce this set of habitat variables to seven new and orthogonal variables. Immature tick abundance varied widely among grids. Regression analysis of tick burdens on the habitat principal components showed that larval burdens were related strongly to the density of woody vegetation and negatively to herbaceous vegetation. Nymphal burdens were related negatively to herbaceous vegetation, but the relationship was not as strong as in the case of larvae. An experimental reduction in the abundance of white-tailed deer (Odocoileus virginianus), the main host of adult ticks, substantially reduced tick burdens and altered their relationships to habitat structure. Nymphal burdens were unrelated to habitat structure following deer removal. Manipulating habitat structure may have utility as a control strategy against this important vector.

Controlled comparison of the BacT/Alert and BACTEC 660/730 nonradiometric blood culture systems

In a collaborative study at three university hospitals, the recovery of microorganisms and the speed of detection of microbial growth by the BacT/Alert (Organon Teknika Corporation, Durham, N.C.) and BACTEC 660/730 (Becton-Dickinson Diagnostic Instrument Systems, Sparks, Md.) nonradiometric blood culture systems were compared. A total of 5,918 comparisons were made between BacT/Alert aerobic and BACTEC NR 6A bottles and 5,992 comparisons were made between BacT/Alert anaerobic and BACTEC NR 7A bottles. Each bottle was inoculated with 5 ml of blood. The overall recoveries of microorganisms from the two aerobic bottles were comparable; members of the family Enterobacteriaceae were recovered more often from BacT/Alert aerobic bottles alone (P less than 0.001). The overall recoveries of microorganisms from the anaerobic bottles were not significantly different. Growth of Staphylococcus aureus (P less than 0.001), coagulase-negative staphylococci (P less than 0.01), streptococci (P less than 0.001), Escherichia coli (P less than 0.01), other members of the family Enterobacteriaceae (P less than 0.02), and Pseudomonas aeruginosa (P less than 0.05) was detected earlier in BacT/Alert aerobic bottles. Growth of S. aureus (P less than 0.001), coagulase-negative staphylococci (P less than 0.05), enterococci (P less than 0.01), Streptococcus pneumoniae (P less than 0.02), viridans group streptococci (P less than 0.05), E. coli (P less than 0.001), Klebsiella pneumoniae (P less than 0.01), and other members of the family Enterobacteriaceae (P less than 0.001) was detected earlier in BacT/Alert anaerobic bottles. In a system-versus-system comparison, more gram-positive cocci were recovered from the BACTEC system alone (P < 0.05), and more members or the family Enterobacteriaceae were recovered from the BacT/Alert system alone (P < 0.001). As a system, the BacT/Alert system detected growth of S. aureus (P < 0.001), coagulase-negative staphylococci (P < 0.01), streptococci (P < 0.001), E. coli (P < 0.001), other members of the familyEnterobacteriaceae (P < 0.001), and P. aeruginosa (P < 0.05) earlier than the BACTEC system did. Significantly fewer (40 versus 1,183) false-positive results occurred with the BacT/Alert system. We conclude that the BacT/Alert and BACTEC 660/730 nonradiometric systems are comparable for recovering clinically significant microorganisms form adult patients with bacteremia or fungemia, but that the BacT/Alert system detects microbial growth earlier than the BACTEC system does, with significantly fewer false-positive results.

Controlled evaluation of BACTEC PLUS 27 and Roche Septi-Chek anaerobic blood culture bottles

Becton Dickinson Diagnostic Instrument Systems (Sparks, Md.) recently introduced BACTEC high-volume aerobic and anaerobic bottles that accept up to 10 ml of blood for use on their nonradiometric blood culture instruments. Both bottles contain 25 ml of tryptic soy broth, 0.05% sodium polyanetholesulfonate, and mixed resins. We compared the anaerobic bottle, designated BACTEC PLUS 27 (BP27), with the Roche Septi-Chek (RSC) Columbia broth anaerobic bottle in a collaborative evaluation at three university hospitals. A total of 5,152 adequately filled blood cultures were obtained from adult patients with suspected bacteremia or fungemia. Staphylococcus aureus was recovered significantly more often (P less than 0.03) from BP27 bottles alone; there were no other significant differences in yield. When microorganisms were recovered from both anaerobic bottles, growth was detected earlier in BP27 than it was in RSC (P less than 0.001), especially for S. aureus (P less than 0.001) and Staphylococcus epidermidis (P less than 0.02). We conclude that the yield from BP27 bottles is equivalent to or better (S. aureus) than that from RSC anaerobic bottles with Columbia broth and that speed of detection is superior with BP27 bottles.

Sexual and transovarian transmission of Crimean-Congo haemorrhagic fever virus in Hyalomma truncatum ticks

Male Hyalomma truncatum ticks were inoculated with Crimean-Congo haemorrhagic fever (CCHF) virus, hypostomectomized and then allowed to mate with uninfected females feeding on a naive rabbit. After mating, CCHF virus was reisolated from 2 out of 3 males tested and from 4 of 6 mated, engorged females (titre greater than or equal to 2.2 log LD50/ml). Vertical transmission was then demonstrated by virus reisolation from a portion of 2 of the 6 batches of eggs laid by the positive females. From these 2 positive egg batches, 6 larvae pools were tested with successful virus reisolation from one. Attempts to reisolate CCHF virus from 15 nymph pools of this positive batch of larvae were unsuccessful. Virus reisolation from gonopore-closed female H. truncatum which cofed with preinfected males demonstrated transmission in the absence of copulation. Rabbits that served as bloodmeal sources seroconverted after infestation by infected male ticks. However, CCHF virus was not reisolated from 3 gonopore-closed, engorged females, nor from their eggs, after feeding with hypostomectomized preinfected males. Transmission of CCHF virus during mating or cofeeding of adult H. truncatum, and subsequent transovarial transmission, appear to represent additional mechanisms of infection in the tick population, and may contribute to the maintenance of transmission in nature.

Gastrointestinal cryptococcosis

Cryptococcal infection of the gastrointestinal (GI) tract is rarely reported, either in disseminated disease or as an isolated finding. We report a case of gastric cryptococcal infection diagnosed by endoscopic biopsy as the initial presentation of the acquired immunodeficiency syndrome (AIDS), and an additional seven cases found by reviewing 23 other autopsy cases of disseminated or pulmonary cryptococcal infection. The patient with gastric cryptococcosis was a 38-year-old man who presented with symptoms of gastroesophageal reflux including odynophagia. Upper GI endoscopy showed Candida esophagitis and gastric nodules. Biopsy of the nodules revealed cryptococcal infection and granulomatous inflammation of the fundic mucosa and submucosa. The patient died 3 weeks later despite anti-fungal therapy. Autopsy revealed widespread cryptococcal infection involving the cecum but not the stomach, suggesting that the gastric lesions resolved with therapy. The sites of infection in the seven other cases were esophagus (three), stomach (one), terminal ileum (one), colon (three), gallbladder (one), and in a focus of Kaposi's sarcoma in the wall of the small bowel (one). Esophageal candidiasis was also present in two of the cases of esophageal cryptococcal infection. Predisposing factors were AIDS (3), hematologic malignancy (3), and corticosteroid therapy (1). In summary, we report a case of gastric cryptococcosis and conclude that cryptococcal infection involves the GI tract more commonly than has been previously reported, with 8/24 (33%) cases positive in our autopsy series. Of clinical significance is the observation that GI cryptococcal infection may be the initial presentation of disseminated disease in the immunocompromised patient, and cryptococcal infection of the esophagus may be found in the setting of esophageal candidiasis.

Crimean-Congo haemorrhagic fever virus replication in adult Hyalomma truncatum and Amblyomma variegatum ticks

The kinetics of the replication of the Crimean-Congo haemorrhagic fever virus (CCHFV) was studied in intra-anally inoculated adult Hyalomma truncatum and Amblyomma variegatum ticks. The virus was re-isolated by suckling mouse inoculation and revealed by antigen capture with ground ticks and indirect immunofluorescence of haemolymph. The virus was detected in ticks in the first hours post-inoculation (p.i.) and its replication was observed from 36 h p.i. onwards. Virus titre reached a maximum within 3-5 days then decreased slowly to a level of at 2 log LD50/ml for several months until the end of observations. Several specific, non-identified factors seem to favour CCHFV replication in H. truncatum. Long-term virus persistence seems to occur in CCHFV-infected adult ticks.

Risk factors for Crimean-Congo hemorrhagic fever in rural northern Senegal

The extent of infection among 722 residents of an enzootic focus of Crimean-Congo hemorrhagic fever (CCHF) virus in rural northern Senegal and putative modes of transmission were studied by a cross-sectional seroprevalence survey done from February through May 1989. Anti-CCHF virus IgG was found in 13.1% of 283 persons who completed a standard questionnaire and provided blood samples. Seropositivity rates were similar between sexes and increased significantly with age among nomadic persons. Behavior patterns providing exposure to multifactorial risk factors were gender-based. Male risk factors, primarily associated with herding activities, included sleeping outside during seasonal migrations (also a risk factor for nomadic women), bite by a tick (adult male Hyalomma truncatum), tick bite during the cool dry season, and contact with sick animals. Human infection of CCHF occurred more frequently or with less mortality in the region studied than has been found elsewhere in Africa; however, the rate of seroconversion-associated illness is undetermined. Hyalomma ticks appear to be the primary transmission mode.

Transmission of Crimean-Congo haemorrhagic fever virus from experimentally infected sheep to Hyalomma truncatum ticks

Crimean-Congo haemorrhagic fever (CCHF) virus was inoculated into West African sheep that were simultaneously infested with adult Hyalomma truncatum ticks. Certain sheep developed a viraemia and antibodies, indicating virus infection and replication; however, the length and magnitude of the viraemia and serological responses corresponded to the animals' immunological status. Tick attachment and feeding was not influenced by sheep infection. CCHF virus infection was acquired by 11-33% of female and 0-60% of male ticks. Infection in the ticks did not influence their feeding success, as judged by weight at drop-off, and the weight of eggs produced by infected and non-infected ticks was similar. Transovarial transmission of CCHF virus was demonstrated in 2 of 12 (17%) egg batches from infected female ticks, but in none of 19 egg batches from ticks that tested negative for CCHF virus. Our results suggest that under certain ecological conditions, sheep may serve to amplify CCHF virus in nature through horizontal transmission and that the maintenance cycle also may be influenced by transovarial transmission to the next generation of ticks.

Controlled evaluation of BACTEC Plus 26 and Roche Septi-Chek aerobic blood culture bottles

Blood culture bottles that accept up to 10 ml of blood have recently been introduced for the BACTEC nonradiometric blood culture system. The new formulation, designated BACTEC Plus, contains 25 ml of tryptic soy broth, 0.05% sodium polyanetholesulfonate, and mixed resins. In a collaborative study conducted at three university hospitals, we evaluated the BACTEC Plus 26 (BP26) aerobic bottle and the Roche Septi-Chek aerobic bottle with its agar slide paddle in 5,293 paired blood cultures. Significantly more microorganisms (P less than 0.001), especially Staphylococcus aureus (P less than 0.001), Staphylococcus epidermidis (P less than 0.01), enterococci (P less than 0.005), and members of the family Enterobacteriaceae (P less than 0.005), were detected by the BP26 bottle. When both bottles detected growth, BP26 did so earlier (P less than 0.001). In particular, S. epidermidis (P less than 0.001), streptococci (P less than 0.005), enterococci (P less than 0.05), and members of the family Enterobacteriaceae (P less than 0.001) were detected earlier by the BP26 bottle. We conclude that the BP26 bottle provides a yield and speed of detection of microorganisms superior to those of the Roche Septi-Chek aerobic blood culture bottle.

Issues in cerebrospinal fluid management. CSF Venereal Disease Research Laboratory testing

Three policies for decreasing unnecessary cerebrospinal fluid (CSF) management Venereal Disease Research Laboratory (VDRL) tests were compared. The first policy attempted to educate physicians about the use of serologic tests for diagnosing neurosyphilis but allowed the CSF VDRL to be performed either as a screening test or as a retrospective test. The second policy required that the CSF VDRL be performed as a retrospective test without regard to the patient's serologic status. The third policy required that a patient be seropositive by either rapid plasma reagin (RPR) or fluorescent treponemal antibody absorbance (FTA-ABS) before a CSF VDRL could be performed. Before these policies were instituted, VDRL testing was performed on 18.2% of all CSF samples. The optional and required retrospective policies decreased the CSF VDRL rate to 13.0% and 8.5%, respectively, but the percentages of seropositive patients for whom these procedures were performed were only 7.3% and 12.9%. The third policy decreased the CSF VDRL test rate to 1.8% (P less than 0.001) with seropositivity improving to 90%. To assure serologic tests are obtained in the evaluation of neurosyphilis, requirement for seropositivity must be implemented with the use of retrospective CSF VDRL testing.

Increased abundance, size, and longevity of food-deprived mosquito populations exposed to a fungal larvicide

To determine whether the quantity of food available to mosquitoes in their aquatic environment limits the effectiveness of microbial pathogens as biological control agents, experimentally well-nourished and malnourished larval Aedes aegypti (Linn.) were exposed to graded inocula of the entomopathogenic fungus, Metarhizium anisopliae. First instar larvae were provided access either to 3 or to 5 mg of food, and lots from each food regimen were inoculated with 20, 40, 60, or 80 micrograms of fungal spores/ml water. Application of the fungus to well-nourished larvae reduced the proportion developing to the adult stage, and increased the size of those adults that developed; their survival was not affected. In the case of malnourished larvae, such applications appeared not to effect the proportion of larvae that matured, and, paradoxically, increased the size and longevity of these resulting adults. By destroying a portion of the larvae, the pathogen apparently reduced competition among malnourished larvae, thereby enhancing their survival, as well as the size of the resulting adults. Thus, biocontrol agents may fail when used as larvicides against such nutrient-deprived mosquitoes as frequently occur in nature.