Microtiter assay for detecting Campylobacter spp. and Helicobacter pylori with surface gangliosides which bind cholera toxin

Campylobacter jejuni with Gm1 ganglioside in the core of its lipopolysaccharide has been associated with Guillain-Barré syndrome. Since this epitope may be of considerable pathophysiologic importance and since this ganglioside binds cholera toxin, a rapid screening assay to detect bacteria that bind cholera toxin as an indication of Gm1 on their surfaces was developed. In the assay, bacterial lawns were grown on agar plates, harvested with phosphate-buffered saline, boiled, and incubated with a standard concentration of cholera B subunit. Preparations from strains with Gm1 were observed to inhibit the binding of cholera B subunit to Gm1 in a microtiter enzyme-linked immunosorbent assay. By using this assay with two groups of strains, 37 positive strains were detected among the 197 tested. Species with positive isolates included C. jejuni, Campylobacter coli, and Helicobacter pylori. The assay is capable of testing large numbers of isolates and should prove useful in future clinical and epidemiological studies of bacteria with this epitope.

Detection of Toxoplasma gondii tachyzoites and bradyzoites in blood, urine, and brains of infected mice

Different techniques for identifying Toxoplasma gondii were compared. PCR was used to amplify part of the major surface antigen P30 gene of T. gondii. Amplified-DNA detection with the DNA enzyme immunoassay (PCR-DEIA) was more sensitive than ethidium bromide staining after agarose gel electrophoresis and as sensitive as nested PCR. PCR-DEIA, using common enzyme-linked immunosorbent assay (ELISA) methods, avoids agarose gel electrophoresis for the identification of amplified products. T. gondii can also be detected with equal sensitivity in infected fibroblasts, but only after at least 8 days of cell culture. PCR-DEIA is thus recommended because of its sensitivity and convenience for detecting early parasitemia in the surveillance of toxoplasmosis among pregnant women and immunocompromised hosts. The courses of infection in mice infected with two strains of T. gondii were compared. Tachyzoites of the virulent strain T. gondii RH, killing the host in 4 days, were identified in urine specimens and blood samples of mice 24 to 94 h after inoculation but not in brains, but no antibodies were detected. After intraperitoneal inoculation with cysts of the low-level virulence Beverley strain of T. gondii, parasites were identified in blood samples 4 days later and up to 17 days (but not in urine specimens) and in the brain from day 6 through day 525. By ELISA, high antibody titers were found from day 11 to day 525, with parasitemia preceding the appearance of antibodies. The usefulness of PCR-DEIA tests in conjunction with the search for circulating antibodies for the early diagnosis of toxoplasmosis in humans is discussed.

Molecular characterization of Vibrio cholerae O139 isolates from Asia

In 1992, a serologically novel clone of Vibrio cholerae, designated O139, caused large epidemics of diarrhea in India and Bangladesh. To determine the extent of the spread of V. cholerae O139 worldwide, 484 V. cholerae non-O1 strains isolated from different patients with diarrhea in Thailand, Indonesia, the Philippines, and Peru in 1993 were tested for agglutination in O139 antisera. One hundred fifty-one of these 484 isolates were examined for genes encoding cholera toxin, zonula occlulans toxin, the repetitive sequence 1, and the toxin coregulated pilin A (the V. cholerae virulence gene complex). Thirty-three percent (122 of 364) of V. cholerae non-O1 strains isolated from different patients with diarrhea in Thailand agglutinated in O139 antisera. Ninety-eight percent (120 of 122) of V. cholerae O139 contained the V. cholerae virulence gene complex. None of the 104 V. cholerae non-O1 strains isolated from patients with diarrhea in Indonesia or the 14 strains from patients with diarrhea in the Philippines were serotype O139. Four different ribotypes were found in V. cholerae O139 isolated in Asia. Twenty-three (47%) of 49 Thai O139 strains examined were of different ribotypes than isolates from India and Bangladesh; V. cholerae strains that were not O1 or O139 that were isolated from flies and water in Thailand 11 years previously in 1981 contained the same V. cholerae virulence gene complex found in V. cholerae O1 and O139. This suggests that other unidentified virulence determinants are involved in V. cholerae O139 pathogenesis.

Fractionation and characterization of two forms of peroxidase from Oryza sativa

Peroxidase (E.C. 1.11.1.7., hydrogen donor oxidoreductase) is widely distributed and has been isolated from many higher plants (1). The wide distribution of the enzyme suggests that it could be of great biological importance. However the role that it plays in metabolism is not clear due to the large number of reactions it catalyzes and the considerable number of isozymic species (2). In tomato plants, Evans and Aldridge (3) separated out six isoperoxidases and in a later paper Evans reported 12 isoperoxidases from tomato shoots (4). A homogeneous tomato fruit peroxidase isozyme was obtained by Jen et al. (5) using hydrophobic chromatography. Isozymes were not detected in Euphorbia characias peroxidase (6), in Ipomoea batatas peroxidase (7) and in Hordeum vulgare peroxidase (8). The simultaneous presence of Cu (II) amine oxidase and peroxidase in cell walls suggests that the peroxide generated on oxidation of the amines could be utilized by the peroxidase (6,8,9). In the graminea Oryza sativa, widely distributed, an FAD amine oxidase is present that oxidizes diamines (10). In this plant we also found two isoperoxidases called perox I and II. Only perox I was purified to homogeneity and its enzymatic, physical and chemical properties have been studied.

Campylobacter diarrhea in Alexandria, Egypt

The role of Campylobacter as a cause of bacterial diarrhea in young children in Alexandria, Egypt was investigated. Stools or rectal swabs were collected from 880 children (mean age 9.8 months) presenting to a hospital with the primary complaint of diarrhea and from 1,079 well children (mean age 8.8 months) attending a vaccination clinic. Isolation of Campylobacter was significantly (p<0.0002) more frequent from cases (17.2%) than from controls (6.4%). Campylobacter was isolated from children presenting with diarrhea more frequently than Salmonella (3% isolation rate), Shigella (2% isolation rate), or other bacterial pathogens (1% isolatoin rate). Isolation of Campylobacter was significantly more frequent during the rainy season (p<0.0012). These results implicate Campylobacter as a major bacterial cause of diarrhea for which young children are brought for medical attention in Alexandria, Egypt.

Oral challenge with Aeromonas in protein-malnourished mice

The lack of an animal model for Aeromonas-associated diarrhoea has hindered progress toward understanding the pathogenesis of this potentially important enteric infection. Protein-malnourished mice were challenged orally with Aeromonas strains to determine if diminished levels of resistance would allow the induction of a diarrhoeal response. The 15 Aeromonas spp. faecal isolates used for challenge included 7 A. caviae, 4 A. hydrophila, 1 A. sobria bv. sobria, and 1 A. sobria bv. veronii from patients with diarrhoea, and 2 A. caviae from healthy volunteers. All had at least 1 known virulence marker, with the exception of 1 strain. Mice on the protein deficient diet had lost an average of 23% of their initial body weight at the time of challenge. Although mice consumed 10(8) cfu per day for a minimum of 4 days, none became ill due to Aeromonas spp. ingestion. Aeromonas spp. were isolated from 75% of faecal cultures obtained 7 days after initial challenge, indicating bowel colonization had occurred.

Persistent, recurring diarrhea in a colony of orangutans (Pongo pygmaeus) caused by multiple strains of Campylobacter spp

A colony of 10 orangutans (Pongo pygmaeus) experienced persistent, recurring diarrhea caused by multiple infections with Campylobacter jejuni and C. coli. Infections appeared to have occurred through several mechanisms, including fecal-oral transmission between orangutans, and possibly transmission by houseflies contaminated with the organisms from nearby chicken feces. Among the 14 fecal and environmental C. jejuni isolates, 4 different antibiotic susceptibility profiles were detected; there were also 4 different profiles among the 8 isolates of C. coli. In 5 orangutans, there were back-to-back infections by different strains of C. jejuni, suggesting that a single C. jejuni infection may not confer protective immunity against heterologous strains circulating in the same vicinity. Transmission was effectively interrupted by environmental modifications and a 7-day course of oral erythromycin.

[Arthroplasty of the knee using total condylar prosthesis. Long term results (10 to 17 years) and survival analysis]

INTRODUCTION

This study refers to the first 76 Total Condylar knee prostheses that were implanted in 66 patients, with a minimum follow-up of 10 years.

MATERIALS AND METHODS

There were 54 women and 12 men with an average age of 65 years (range 45-81). The diagnosis was osteoarthrosis in 63 knees and rheumatoid arthritis in 13. We were able to review 54 prostheses with an average follow-up of 13 years (10-17) using the rating system of the Hospital for Special Surgery and the Survivorship analysis.

RESULTS

The results were excellent and good in 72.5 per cent knees and fair and poor in 22 per cent, 3 knees (5.5 per cent) had been revised for deep infection in 2 cases and for aseptic loosening in 1. Pain at rest was absent or mild in all but one patient; walking pain was absent in 32 knees (63 per cent), mild in 12 (23 per cent), moderate in 5 (10 per cent) and severe in 2 (4 per cent). Average range of motion was 89 degrees, ranging from 40 degrees to 120 degrees. A flexion contracture greater 5 degrees was seen in 8 knees (16 per cent). Instability in the frontal plane tested in full extension was more than 5 degrees in 10 patients (19.5 per cent). A significant deterioration of the results occurred in the last 4-5 years, since in 1988 excellent and good results were still 82 per cent. A loss of postoperative alignment of 5 degrees or more was observed in 11 knees: aseptic loosening was identified in 2 of these cases and deformation of the tibial component was seen in 1 knee. In the remaining 8 knees we observed increased lateral instability, compared to the postoperative evaluation. In this group of 8 knees we measured in the AP view the thickness of the tibial component on the lateral and medial side. We found polyethylene wear on the medial side in 4 cases. Ten of the 11 knees with loss of alignment had an early postoperative femoro-tibial axis less than 5 degrees. We observed radiolucent lines in 18 patellar and 27 tibial components. A width greater than 2 mm, correlated to an extension to 5 or more zones, was seen in 3 tibial components with aseptic loosening. Survivorship analysis using aseptic loosening, mechanical failure of the polyethylene and deep infections as end point gave a cumulative success rate at 10 years of 92 per cent% with 95 per cent confidence interval ranging from 85.1 to 98.

DISCUSSION

Our study reports a lower percentage of excellent and good results if compared to other series of Total Condylar prosthesis with a comparable follow-up. A significant deterioration of the results occurred in the last years, but this was often not related to the knee itself but to poor general conditions in some patients. In this series there is a relevant number of knees with a post-operative alignment that today we don't consider correct and all the aseptic loosenings occurred in knees with a tibial component positioned in varus.

CONCLUSION

Survivorship analysis gave a cumulative success rate comparable with those reported in other studies and confirmed the durability and longevity of this model of prosthesis.

Modified CAMP test for biogrouping Vibrio cholerae O1 strains and distinguishing them from strains of V. cholerae non-O1

A modified CAMP test was used to identify 973 Vibrio cholerae isolates by phenotype. Eltor and non-O1 strains were CAMP positive; classical strains were CAMP negative. Sausage-shaped zones of hemolysis of eltor strains were easily distinguished from narrower bands of non-O1 isolates. For O1 isolates, there was 100% agreement between the CAMP test and inhibition by polymyxin B.

Safety, immunogenicity, and transmissibility of single-dose live oral cholera vaccine strain CVD 103-HgR in 24- to 59-month-old Indonesian children

Recombinant A-B+ Vibrio cholerae O1 strain CVD 103-HgR is a safe, highly immunogenic, single-dose live oral vaccine in adults in industrialized countries. Safety, excretion, immunogenicity, vaccine transmissibility, and environmental introduction of CVD 103-HgR were investigated among 24- to 59-month-old children in Jakarta. In 81 households, 1 child was randomly allocated a single dose of vaccine (5 x 10(9) cfu) and another, placebo. Additionally, 139 unpaired children were randomly allocated vaccine or placebo. During 9 days of follow-up, diarrhea or vomiting did not occur more often among vaccines than controls. Vaccine was minimally excreted and was isolated from no controls and from 1 (0.6%) of 177 unvaccinated family contacts. A 4-fold or higher rise in serum vibriocidal antibody was observed in 75% of vaccines (10-fold rise in geometric mean titer over baseline). Of 135 paired placebo recipients or household contacts, 5 had vibriocidal seroconversions. Moore swabs placed in sewers and latrines near 97 households failed to detect vaccine. These observations pave the way for a large-scale field trial of efficacy.

Enterotoxigenic Escherichia coli and other causes of infectious pediatric diarrheas in Jakarta, Indonesia

A hospital stool survey of Indonesian children less than 5 years of age determined the prevalence of diarrhea caused by enterotoxigenic Escherichia coli (ETEC) and other bacterial enteropathogens, compared to non-diarrheic control patients. ETEC were the second most frequent cause of diarrhea, isolated from 16 of 194 (8.2%) of patient's stools compared to 2 of 97 (2.1%) of control stools. The highest prevalence was in infants 12 to 23 months of age (17.9%).

Use of vaginal tampons in sewer surveys for non-O1. Vibrio cholerae

Vaginal tampons were shown to be a practical alternative to conventional Moore swabs for isolating Vibrio cholerae from sewage. Associated laboratory investigations demonstrated improved isolation of V. cholerae by using 12- or 18-h enrichments in alkaline peptone water, in comparison with 6-h enrichments, when cultures were incubated at ambient temperatures.

Detection of immunoglobulin A in urine specimens from children with Campylobacter-associated diarrhea by a chemiluminescent indicator-based western immunoblot assay

A Western blot (immunoblot) assay was used to detect Campylobacter-specific immunoglobulin A in urine. Acute-phase urine samples from six children with Campylobacter diarrhea had titers ranging from 2 to 8. The highest titer was detected 4 days postonset. Campylobacter-specific immunoglobulin A was undetectable in the paired convalescent-phase specimens and urine samples from three control children.

[Comparison of Gunther, Filcard and LGM definitive caval filters. Our experience]

The authors report their experience with 30 caval filters placed throughout 3 years, and compare it with the data from the literature. In 8 patients (26.5%) Gunther filters were used, in 16 cases (53.5%) Filcard filters (4 DF-01 and 12 DF-04) and finally the last 6 patients (20%) were treated with LGM filters. In 18 cases (60%) the filters were positioned through right common femoral vein, whereas in the remaining 12 patients (40%) they were placed through the right internal jugular vein. Early complications were 1 mispositioning (3.3%) with a LGM filter, 2 incomplete opening (6.6%) of Filcard DF-01 filters, 3 significant tiltings (10%) with Filcard DF-04 filters. One patient (3.3%) died one week after the placement of a Gunther filter. The radiologic follow-up, which included controls with conventional radiology, US, cavography, MR and CT revealed no later complications. All the filters exhibited both advantages and disadvantages. Although all the filters commonly in use are effective to prevent pulmonary embolism, further experience is necessary to find out the "ideal" filter.

Campylobacter-associated diarrhoea in Egyptian infants: epidemiology and clinical manifestations of disease and high frequency of concomitant infections

A diarrhoeal disease survey in Alexandria, Egypt determined the prevalence, seasonality, and household risk factors for Campylobacter-associated diarrhoea in young children. The study population was 880 children (mean age = 9.8 months) presenting with diarrhoea at one of two hospitals. A control group consisted of 1,079 healthy children (mean age = 8.8 months) attending two nearby vaccination clinics. The overall isolation frequencies for Campylobacter spp. were 16.8% for cases and 6.4% for the comparison group (p = 1 x 10(-8)). Other enteropathogens detected in diarrhoeal stools were: rotavirus (28.6%), Giardia lamblia trophozoites (21.3%), enterotoxigenic Escherichia coli (8.7%), Entamoeba histolytica (3.9%), Salmonella spp. (2.7%), and Shigella spp. (1.8%). There were few or no isolates of Aeromonas spp., Vibrio spp., Yersinia spp., or Plesiomonas spp. Comparisons among cases showed that Campylobacter spp. isolations were more prevalent during the rainy season (p = 0.001) and positively associated with keeping fowl in the home (p = 0.003) or having an outdoor source of drinking water (p = 0.029). Among Campylobacter-positive diarrhoeal patients, 69.0% had faecal leukocytes present and 16.3% had bloody stools. Patients with Campylobacter-positive diarrhoeal stools were frequently co-infected with rotavirus (28.6%) or G. lamblia (24.5%).

[Outbreak of paratyphoid fever among Peruvian naval personnel]

A retrospective epidemiological study was conducted in connection with an outbreak of paratyphoid fever at a Peruvian naval installation in Callao. The study sought to determine the magnitude of the outbreak, the source of infection, the attack rates, the persistence of bacilli excretion, and the clinical picture of the disease. The source of Salmonella paratyphi B infection had been a meal of chicken and rice served to around 400 members of the naval police. Over a period of three weeks, 21 persons were hospitalized and 52 received outpatient treatment at the naval hospital. In addition, through a questionnaire it was revealed that 86 unreported cases of diarrhea related to the outbreak had occurred. The most common clinical manifestations were fever, headache, weakness, anorexia, abdominal pain, and diarrhea. The general attack rate was 39.8%. In a follow-up survey carried out 37 days after exposure, fecal cultures indicated that 8.5% of the persons affected continued to excrete the microorganism. The high rates of attack and transmission of S. paratyphi B in this outbreak point up the considerable pathogenicity and virulence of some strains of the microorganism and their impact on public health. It is suggested that preventive measures be taken at naval and other similar installations, including the education of workers who handle and prepare food, in order to ensure proper hygiene.

The etiology of diarrhea among American adults living in Peru

During 1984-1989, 655 diarrheic and 287 nondiarrheic stool specimens from adult U.S. citizens living in Lima, Peru were tested for presence of bacterial enteropathogens. Frequencies of isolation among diarrheic specimens were: Shigella 9.8%; Campylobacter 6.1%; enterotoxigenic Escherichia coli (ETEC) 6.0%; Plesiomonas 2.0%; Salmonella 1.4%; and Vibrio 0.6%. Isolates recovered from non-diarrheic stools were: Shigella 4.5%; Campylobacter 2.1%; Salmonella 1.0%; ETEC 0.7%; Plesiomonas 0.7%; and Vibrio 0.3%. Aeromonas, an unproven cause of diarrhea, was isolated from 9.2% of cases and 3.5% of controls. Disease occurrence was strongly associated with isolation of Shigella, ETEC, Campylobacter, or Aeromonas (p less than or equal to 0.01). During the 6-year period of study, shifts in the dominant phenotypes of Shigella and Campylobacter occurred which may have important implications for vaccine development and intervention strategies.

The etiology of childhood diarrhea in northern coastal Peru: the 1989 Fuerzas Unidas Humanitarian Civic Action--a model for international and interservice cooperation, community service, and scientific opportunity

As a humanitarian civic action project, American and Peruvian military medical personnel established a temporary clinic in Dos Palos, Peru. Fecal specimens from 20 diarrheic children and 10 non-diarrheic controls were tested for common agents of diarrhea. Enteropathogens detected in diarrheic stools were enterotoxigenic Escherichia coli (ETEC; 30%), Aeromonas (20%), enteropathogenic E. coli (15%), and Campylobacter (15%). Isolates from control specimens were Aeromonas (10%) and Campylobacter (10%). ETEC-associated diarrhea was more common in this study (30%) than in three similar populations studied in Lima (2-16%). The results suggest that the northern coastal area of Peru is a relatively high-risk area for diarrhea caused by ETEC.

High frequency of coinfecting enteropathogens in Aeromonas-associated diarrhea of hospitalized Peruvian infants

Rectal swabs from 391 infants less than 18 months of age who were hospitalized with acute diarrhea and from 138 similarly aged healthy infants were examined for the etiologic agents of diarrhea. Aeromonas spp. were recovered from 205 of 391 (52.4%) diarrheic patients, whereas they were recovered from 12 of 138 (8.7%) controls (P less than 10(-11). Among the 205 Aeromonas-positive diarrheic patients, 118 (57.6%) were found to be coinfected with other common enteropathogens. Of the 164 Aeromonas-positive initial diarrheic specimens, 82 (50.0%) had one or more other enteropathogens present; 30 patients were coinfected with rotavirus, 20 with enterotoxigenic Escherichia coli, 16 with Campylobacter spp., 14 with Shigella spp., 13 with enteropathogenic E. coli, 4 with Vibrio spp., 1 with Salmonella spp., and 1 with Plesiomonas spp. of Aeromonas strains from cases compared with that from controls supports an etiologic role for this organism. However, frequent concomitant infections with other well-recognized enteropathogens and a lack of disease correlation with common Aeromonas phenotypes suggest that only a subset of Aeromonas strains may be diarrhea causing and that such strains may be common to several of the existing species.

Diarrhea and intestinal invasiveness of Aeromonas strains in the removable intestinal tie rabbit model

Twelve Aeromonas strains were tested for virulence by using the removable intestinal tie adult rabbit diarrhea model. Mortality was 50% or greater for 7 of 12 strains; 23 of 37 rabbits that died developed diarrhea before death, and 11 of 27 surviving rabbits developed diarrhea. Aeromonas bacteremia was detected in 36 of 37 (97%) animals that died, but only in 2 of 27 (7%) survivors. Death, diarrhea, and bacteremia were all strongly strain dependent. Gastrointestinal lesions varied from moderate focal enteritis to severe multifocal necrosis and hemorrhage of the ileal mucosa, often accompanied by hepatic and splenic lesions. Intestinal colonization assays performed after infection indicated that the ileum was the most heavily colonized portion of the gut and the probable site of invasion. The application of the removable intestinal tie adult rabbit diarrhea model for intestinal challenge with Aeromonas strains has shown that some isolates are capable of invading the mucosa of rabbits, causing diarrhea and bacteremia. These data suggest that such strains may be important in causing human invasive diarrhea.

Risk of hepatitis B infection among Egyptians infected with Schistosoma mansoni

Three hundred twenty-four individuals in a farming village located in the Nile Delta of Egypt were serially tested for hepatitis markers and Schistosoma mansoni to determine whether there is an increased risk of hepatitis B in persons infected with schistosomiasis. One-half of the subjects had stools positive for S. mansoni. Thirty-seven percent of the individuals had been infected with hepatitis B, and 3% were chronic HBsAg carriers. No statistical association was found between S. mansoni infection and hepatitis B infection, including chronic hepatitis B. Although there was no evidence of an association between these 2 pathogens, larger nonhospital based studies are needed to resolve this question.

Evaluation of febrile patients in Port Sudan, Sudan: isolation of dengue virus

One hundred consecutive patients admitted to the Port Sudan Hospital with a temperature greater than or equal to 100 degrees F were evaluated. Enteric fever was diagnosed in 19 patients and malaria in 13. Virologic studies identified 21 cases of dengue infection. One dengue 1 and 17 dengue 2 infections were diagnosed by viral isolation. Three untyped dengue infections were identified serologically. The clinical presentation and course of patients infected with dengue virus were most consistent with classic dengue fever. There was no evidence of hemorrhagic phenomena or shock in any of the dengue-infected patients. Both dengue 1 and 2 must be considered causes of acute fever in East Africa.

In vivo protection of penicillin-susceptible Bacteroides melaninogenicus from penicillin by facultative bacteria which produce beta-lactamase

We investigated the possibility that beta-lactamase producing strains of Klebsiella pneumoniae and Staphylococcus aureus can protect organisms of the Bacteroides melaninogenicus group from penicillin. A mixed infection was induced in mice in the form of a subcutaneous abscess involving a penicillin-susceptible encapsulated B. melaninogenicus, and a beta-lactamase producing strain of either K. pneumoniae or S. aureus. The infected animals were treated for 7 days with single or combined antimicrobial therapy. The single agents used were penicillin, clavulanic acid, metronidazole, and gentamicin. The antimicrobial combinations were penicillin and clavulanic acid, penicillin and gentamicin, and metronidazole and gentamicin. Administration of a single agent was effective in treating abscesses caused by susceptible organisms. The only effective therapy for mixed infections was by combination therapy of penicillin and clavulanic acid or metronidazole and gentamicin. This study supports the hypothesis that beta-lactamase producing facultative bacteria may shield their anaerobic counterparts from penicillin therapy, thereby contributing to the persistence of the infection.

In-vivo protection of group A beta-haemolytic streptococci from penicillin by beta-lactamase-producing Bacteroides species

The incidence of persistent group A beta-haemolytic streptococci in tonsils, despite penicillin therapy, has increased in recent years. beta-Lactamase-producing organisms have previously been recovered from 74% of patients with persisting group A streptococci. We investigated the possibility that beta-lactamase-producing strains of Bacteroides spp. can protect streptococci from penicillin. A mixed infection was induced in mice in the form of a subcutaneous abscess involving a penicillin-susceptible group A streptococcus, and a beta-lactamase-producing strain of either Bact. melaninogenicus or Bact. fragilis. The infected animals were treated for seven days with parenteral penicillin, penicillin and clavulanic acid or clindamycin. Penicillin treatment prevented the formation of abscesses in animals inoculated with group A streptococci alone, but not in those inoculated with group A streptococci and Bacteroides spp. We attributed this resistance to penicillin therapy, and the subsequent formation of abscesses in mice, to protection of the streptococci from penicillin by beta-lactamase-producing strains of Bacteroides spp. Effective therapy for mixed infections was achieved when clavulanic acid, a beta-lactamase inhibitor, was administered with penicillin. A similar effect was noted with clindamycin, which is active against both group A streptococci and Bacteroides spp.

An analysis of the relationship of host factors to clinical falciparum malaria by multiple regression techniques

Clinical records of 58 infections with the Vietnam Smith strain of Plasmodium falciparum in human volunteers were studied in order to 1) characterize the clinical course of infections; 2) investigate the effects of race, weight, age, method of induction, and previous malaria experience on the course of infection using methods of multiple regression; and 3) establish whether differences in drug-treatment groups may have influenced the current study results. We found that blacks tolerated infection better than whites, that heterologous as well as homologous strain immunity persists after infection and that these results could not be attributed to differences in treatment. The clinical course of infections with the Vietnam Smith strain of P. falciparum is described.