Plasmodium falciparum in Kenya: high prevalence of drug-resistance-associated polymorphisms in hospital admissions with severe malaria in an epidemic area.

During an epidemic of Plasmodium falciparum malaria in Chogoria, Kenya, P. falciparum DNA was collected from 24 cases of severe malaria admitted to hospital for parenteral quinine treatment. These patients had all failed first- (chloroquine) and second-line (sulfadoxine-pyrimethamine or amodiaquine) drug treatments. Twenty-two (92%) of the 24 patients sampled carried parasites with the (Asn)86(Tyr) point mutation in the pfmdr1 gene (chromosome 5), 20 (83%) had an (Asp)1246(Tyr) mutation and 18 (82%) had both of these mutations. These alleles are both reported to be associated with chloroquine-resistance. Polymorphisms in the cg2 gene (chromosome 7) are also associated with chloroquine resistance, and 18 (75%) of the 24 parasite samples each had the cg2 and pfmdr1 polymorphisms. These 18 samples also had the mutations associated with resistance to pyrimethamine and sulfadoxine: (Asn)51(Ile), (Cys)59(Arg) and (Ser)108(Asn) of gene dhfr (chromosome 4) and (Ala)437(Gly) and (Lys)540(Glu) of dhps (chromosome 8), respectively. Genotyping of the parasites from all 24 patients revealed extensive diversity in the sequences for the merozoite surface antigens (MSA-1 and MSA-2) and the glutamate-rich protein (GLURP) and indicated that each sample contained more than one parasite clone. Although samples from non-admitted malaria cases were not available, it appears that drug resistance may have played an important role in the development of severe malaria in this epidemic.

IgG antibody to pneumococcal capsular polysaccharide in human immunodeficiency virus-infected subjects: persistence of antibody in responders, revaccination in nonresponders, and relationship of immunoglobulin allotype to response.

Human immunodeficiency virus (HIV)-infected persons are less likely than are noninfected persons to respond to vaccination with pneumococcal polysaccharides (PPS). Among those who respond, however, similar IgG levels may be achieved. HIV-infected men immunized with pneumococcal vaccine were classified as high- or low-level responders (IgG > or = 1 microgram/mL for > or = 3 of 5 PPS [high] or for < or = 1 PPS [low]). One and 2 years after immunization, geometric mean IgG levels and the percentages of subjects with IgG levels > or = 1 microgram/mL were similar for HIV-infected and for healthy high-level responders (controls) for all PPS except for serotype 8. Among HIV-infected low-level responders, revaccination with a double dose of pneumococcal vaccine did not stimulate IgG responses. Responsiveness of HIV-infected white patients was significantly associated with the Km(1)- negative allotype. These findings support current general recommended guidelines for administering pneumococcal vaccine to HIV-infected persons. Nonresponders will not benefit from revaccination.

Evidence that bismuth salts reduce invasion of epithelial cells by enteroinvasive bacteria.

The effects of sublethal concentrations of bismuth salts on bacterial invasion of mammalian cells were investigated. Pepto-Bismol, bismuth subsalicylate, and bismuth oxychloride, produced by interacting bismuth subsalicylate and simulated gastric juice, in suspension at concentrations as low as 1.4 mM significantly interfered with the invasion of RPMI-4788 cells by two different strains of Yersinia enterocolitica. Invasion of the mammalian epithelial cells by other enteric bacteria was also reduced significantly by some of these bismuth salts. Commercially obtained bismuth oxychloride, bismuth sulfide, and sodium salicylate had no affect on invasion by Y. enterocolitica. Exposure of Y. enterocolitica 8081c to Pepto-Bismol for as brief a time as 5 min was sufficient to produce the inhibitory effect. Removal of bismuth bound to bacteria by sodium potassium tartrate did not reverse the inhibition. Electron-dense deposits are observed in Y. enterocolitica 8081c exposed to bismuth subsalicylate, suggesting that interference of invasion may result from bismuth permeation of the bacterial cell wall.

Deposition of bismuth by Yersinia enterocolitica.

Yersinia enterocolitica 8081c cultures in exponential growth were incubated for 1 h in 0.1% microcrystalline bismuth subsalicylate (BSS) suspensions. Scanning electron microscopy (SEM) revealed microcrystals directly bound to BSS-treated bacteria. Energy dispersive spectroscopy (EDS) X-ray microanalysis of the attached microcrystals confirmed that the crystals were the microcrystalline BSS. X-ray spectra positive for bismuth were also obtained by SEM-EDS X-ray microanalysis of whole bacteria, suggesting metal incorporation into the bacteria in regions absent of bound microcrystals. Transmission electron microscopy of thin sections of embedded preparations of BSS-treated exponential-growth-phase bacteria showed electron-dense deposits in the periphery of the bacteria. Y. enterocolitica cultures that were in stationary phase at the time of incubation with microcrystalline BSS showed no evidence of the electron-dense deposits and EDS spectra were negative for bismuth. Bacteria incubated in the absence of microcrystalline BSS also lacked electron-dense deposits. Scanning transmission electron microscopy used in conjunction with EDS X-ray microanalysis to view and analyze semi-thick sections (250-300 nm) of embedded preparations of BSS-treated bacteria in exponential growth confirmed that the electron-dense deposits at the periphery of the bacteria are the sites of bismuth depositions.

Pulmonary infections due to Legionella in immunocompromised patients.

At present, 11 different species of Legionella have been implicated in human disease. It has become apparent that disease caused by Legionella is acquired from a variety of environmental sources and that water is the factor that links many of them. Patients who are immunosuppressed, such as individuals receiving cancer chemotherapy or therapy designed to prevent organ rejection, are particularly susceptible to such environmental sources. It appears that intact cell-mediated immunity is more important in host defense than are adequate numbers of granulocytes or immunoglobulin concentrations. Diagnostic steps should be undertaken in all patients developing nosocomial pneumonia who present with a picture suspicious for this disorder. In the meantime, appropriate antimicrobial therapy with erythromycin and rifampin should be begun. If clusters of cases are detected in a hospital, immediate steps should be taken to attempt to isolate the organism from any aqueous environmental sources, and if found appropriate, steps taken. Awareness of the threat of legionnaires' disease must be maintained among clinicians and hospital epidemiologists because it is unlikely that the problem of nosocomial legionnaires' disease will disappear.

Lack of association between genital mycoplasmas and infertility.

We studied the relation between colonization with Mycoplasma hominis and Ureaplasma urealyticum, and the results of infertility studies in 205 women with involuntary infertility of at least one year's duration. Isolation of M. hominis (but not of U. urealyticum) was significantly (P = 0.002) more common in patients with a history of pelvic inflammatory disease. However, no relation could be shown between these genital mycoplasmas and any of the following: evidence of prior pelvic inflammatory disease as determined by hysterosalpingography and laparoscopy; cervical inflammation; numbers and motility of spermatozoa on postcoital test; pyosemia; quality of cervical mucus; whether the cause of infertility was related to male or female factors, both, or neither; and occurrence and outcome of subsequent pregnancy. Mycoplasmas were cultured from only 10 of 203 endometrial biopsy specimens (4.9 per cent), and in no instance was inflammation associated with this finding. Out studies do not support a role for genital mycoplasmas in the cause of infertility.

The kinetics of early inflammatory events during experimental pneumonia due to Legionella pneumophila in guinea pigs.

An animal model of Legionella pneumophila pneumonia was developed to study aerosol infection, pathogenesis, and pulmonary host defense mechanisms. Guinea pigs were exposed in an inhalation facility that limited the aerosol of L pneumophila to the snout. Bronchoalveolar lavage was used to sample airspace cells, secretions, and bacteria during developing infection in 79 exposed animals and 13 uninfected controls. An influx of polymorphonuclear neutrophils followed exponential bacterial growth during the initial three days of infection and coincided with limitation of the increase in bacteria recovered. A macrophage influx occurred at three to five days. Bacteria were eliminated from the lung by 11 days after exposure. Albumin in lavage fluid peaked at two days. Most viable L pneumophila organisms were associated with alveolar macrophages, whereas most of the bacteria associated with polymorphonuclear neutrophils were nonviable. Recruited, and possibly immune, defenses appear to be required for successful resolution of legionella pneumonia.

Activity of trimethoprim (TMP), sulphamethoxazole (SMX) and the combination against Bacteroides fragilis group isolates.

The in-vitro efficacy of trimethoprim/sulphamethoxazole (TMP/SMX) was tested against 59 isolates belonging to the Bacteroides fragilis group of bacteria and was shown to be dependent upon the inoculum size. With an inoculum of 3 X 10(5) colony forming units (cfu), 98% of these isolates were susceptible to the combination, whereas with a higher inoculum of 10(6) cfu, 88% were susceptible. None of the isolates were susceptible to less than 2 mg/l of TMP, whereas 57 (97%) were susceptible to SMX at the lower inoculum and 21 (36%) at the higher inoculum. These data indicate that TMP/SMX has moderate activity against organisms of the Bact. fragilis group when tested at an inoculum of 10(6) cfu.

Protein and antibody in lavage fluid of guinea pigs with Legionella pneumophila pneumonia.

Guinea pigs were infected in an inhalation facility that limited an aerosol of L. pneumophila to the snout, as previously reported in detail (Davis et al., 1982). Individual animals were sacrificed for study either immediately after exposure, at 16 hours, at days one through seven, or at 11 days. Bronchoalveolar lavage was carried out to obtain fluid to study the following: total protein, albumin and immunoglobulin G (IgG) concentrations, and the titer of antibody to L. pneumophila. Antibody also was measured in serum obtained at the time of sacrifice. Concentrations of total protein, albumin, and IgG in lavage fluids peaked 2 days after exposure and correlated with the appearance of maximal numbers of polymorphonuclear cells in the lungs. Presumably, this increased protein resulted from exudation of serum across the alveolar-capillary membrane, which loses its integrity secondary to pneumonia. However, the ratio of IgG/albumin was elevated in animals studied 11 days after exposure even though the concentration of albumin was normal by this time. One possible explanation for this observation is that IgG was being produced in the lung. Antibody in lavage fluid was detected 7, and 11 days post-exposure, and might be important in the recovery of guinea pigs from this infection.

Evidence of prior pelvic inflammatory disease and its relationship to Chlamydia trachomatis antibody and intrauterine contraceptive device use in infertile women.

A total of 204 infertile women attending the Infertility Clinic of the Medical Center Hospital of Vermont were studied for the possible role of Chlamydia trachomatis and intrauterine contraceptive device (IUCD) use as factors related to their infertility. All patients had had at least 1 year of involuntary infertility. All but one woman had negative cultures for C. trachomatis, but a highly significant correlation (p less than 0.001) was evident between evidence of prior pelvic inflammatory disease (PPID) as documented by hysterosalpingograms and/or laparoscopy and the prevalence of chlamydial antibody. Furthermore, a significant (p = 0.01) correlation could be shown between the prevalence of the antibodies and adnexal adhesions. IUCD use could also be shown between the prevalence of the antibodies and adnexal adhesions. IUCD use could also be shown to correlate significantly (p less than 0.001) with PPID, and a detailed statistical analysis indicated that the two factors, antibody to C. trachomatis and a history of IUCD use, were independently related to PPID. Only about one third of the patients with PPID could ever recall having had an illness consistent with PID. Subsequent to the infertility workup, 76 of these women became pregnant and there was a significant (p less than 0.001) correlation between the occurrence of ectopic pregnancy and antibody to C. trachomatis. A significant (p = 0.01) correlation was also noted between a history of IUCD use and subsequent ectopic pregnancy. From these data it appears that antecedent infection with C. trachomatis, as measured by antibody prevalence, and a history of IUCD use are important factors in infertility of tubal origin and are also related to ectopic pregnancy.

Lack of protection by pneumococcal vaccine after splenectomy in mice challenged with aerosolized pneumococci.

The efficacy of pneumococcal vaccine given after splenectomy lacks experimental validation. Adult CD-1 male mice that received type III pneumococcal capsular polysaccharide vaccine 1 microgram IP, 48 hours postsplenectomy and 7 days before challenge with aerosolized type III Streptococcus pneumoniae had a significantly higher mortality (96%) compared to immunized controls (64%) (p less than 0.002). The vaccine protected immunized sham-operated mice compared to unimmunized controls (p less than 0.015). Mice immunized 7 days before splenectomy were equally protected when compared to immunized sham-operated mice (p = NS). All deaths were secondary to culture-proven pneumococcal infection. These findings corroborate previous experimental and clinical studies demonstrating an impaired immunologic response and increased susceptibility to infection in asplenic individuals. Pneumococcal vaccines should be given before nonemergent splenectomy. Alternatives to splenectomy should be considered for patients with traumatized spleens where possible.

Legionnaires' pneumonia after intratracheal inoculation of guinea pigs and rats.

We have developed a model of legionnaires' pneumonia in guinea pigs and rats. A reproducible population of Legionella pneumophila was obtained in late exponential growth phase and inoculated into the trachea of young animals. Either immunologic or microbiologic evidence of infection was demonstrated in 27 or 28 guinea pigs and 19 of 20 rats that had been inoculated with 10(5) to 10(7) colony-forming units. An acute pneumonia that resembled human legionnaires' disease was produced in both species, and Legionella antigen was closely related to inflammation in the distal air spaces. A fatal illness was produced in guinea pigs, and pneumonia was more extensive than in rats. Extrapulmonary inflammatory lesions, particularly splenic necrosis, were more frequent in guinea pigs than in rats. Each rodent species has potential advantages for testing specific questions and both should be useful for future investigations.

Legionnaires' pneumonia after aerosol exposure in guinea pigs and rats.

We developed an animal model of Legionnaires' pneumonia to permit study of aerosol infection, pathogenesis, and pulmonary host defense mechanisms in this disease. Guinea pigs and rats were exposed in a nose-only inhalation facility for 30 min to an aerosol of Burlington serogroup 1 Legionella pneumophila. Lungs contained 10(3) to 10(4) L. pneumophila immediately after exposure. Both guinea pigs and rats developed pneumonia, with 100% infectivity by microbiologic, histologic, and serologic criteria. Guinea pigs demonstrated illness, fever, and 56% mortality; rats showed little illness and 11% mortality. In both species, diffuse patchy pneumonitis coalesced and consolidated as the disease progressed. Aerosol challenge with 3H-L. pneumophila showed exponential growth of the bacteria in the lungs of both species. Guinea pigs and rats can be infected by aerosol exposure to L. pneumophila to produce a disease that closely simulates human Legionnaires' pneumonia. Rapid initial intrapulmonary growth suggests that resident lung defense mechanisms are quite ineffective against L. pneumophila, and that recruited or immunospecific defenses may be more critical in the outcome of infection. The difference in severity of illness between guinea pigs and rats may be exploited for different experimental designs.

Activity of cefoperazone and two beta-lactamase inhibitors, sulbactam and clavulanic acid, against Bacteroides spp. correlated with beta-lactamase production.

A total of 102 isolates of Bacteroides spp. were studied for beta-lactamase production and susceptibility to cefoperazone alone or in combination with either of the beta-lactamase inhibitors sulbactam and clavulanic acid. The geometric mean minimal inhibitory concentration of cefoperazone alone was 31.5 micrograms/ml and when combined with 10 micrograms of sulbactam per ml or 2 micrograms of clavulanic acid per ml was reduced to 5.4 and 9.2 micrograms/ml, respectively. When bacterial suspensions were tested for beta-lactamase production with nitrocefin, 91 (89.2%) of these isolates produced the enzyme. The geometric mean minimal inhibitory concentrations of cefoperazone rose only slightly for isolates with low or intermediate enzyme activity but rose significantly for those with high activity. The addition of EDTA to cefoperazone significantly more frequently enhanced the activity of cefoperazone against beta-lactamase-negative as opposed to beta-lactamase-positive isolates. Furthermore, EDTA resulted in synergistic activity of the cefoperazone-sulbactam combination on beta-lactamase-positive isolates for which the combination had previously not shown a synergistic effect. This study demonstrates the relationship between beta-lactamase production and the resistance of Bacteroides spp. to cefoperazone and shows that inhibition of these enzymes can reverse this resistance.

Legionnaires' disease and fever of unknown origin.

In a patient with fever of unknown origin and granulomas of the liver extensive serological testing revealed a significant rise in antibodies only to Legionella pneumophila despite the fact that he never was shown to have pneumonia. Absorption studies yielded additional evidence that this immunological response was specific for L. pneumophila. Bacteremia and extrapulmonary involvement, including the liver, has been shown with L. pneumophila, but never without pneumonia. Furthermore, granulomas of the liver have not been described in connection with legionellosis. This patient is regarded as a case of fever of unknown origin related to L. pneumophila infection.

Vancomycin for treatment of bacterial meningitis.

Clinical experience with vancomycin for the treatment of bacterial meningitis has not been extensive. Presently available data indicate that when meningeal inflammation is present intravenously administered vancomycin penetrates into cerebrospinal fluid and therapeutically effective levels of drug therein are frequently attained. Treatment of meningitis with vancomycin has been effective in clinical situations that precluded the use of the commonly administered agents, i.e., in infections due to resistant strains or to unusual organisms, in patients allergic to penicillin, and in patients for whom therapy with a first-choice antibiotic has failed. When response to intravenously administered vancomycin was unsatisfactory, the addition of intrathecal therapy resulted in a favorable outcome in some patients. Combination therapy with agents that act synergistically with vancomycin has been beneficial. Vancomycin warrants serious consideration as a useful alternate antibiotic for the treatment of bacterial meningitis.