Sulfur oxidation and reduction are coupled to nitrogen fixation in the roots of the salt marsh foundation plant Spartina alterniflora.

Heterotrophic activity, primarily driven by sulfate-reducing prokaryotes, has traditionally been linked to nitrogen fixation in the root zone of coastal marine plants, leaving the role of chemolithoautotrophy in this process unexplored. Here, we show that sulfur oxidation coupled to nitrogen fixation is a previously overlooked process providing nitrogen to coastal marine macrophytes. In this study, we recovered 239 metagenome-assembled genomes from a salt marsh dominated by the foundation plant Spartina alterniflora, including diazotrophic sulfate-reducing and sulfur-oxidizing bacteria. Abundant sulfur-oxidizing bacteria encode and highly express genes for carbon fixation (RuBisCO), nitrogen fixation (nifHDK) and sulfur oxidation (oxidative-dsrAB), especially in roots stressed by sulfidic and reduced sediment conditions. Stressed roots exhibited the highest rates of nitrogen fixation and expression level of sulfur oxidation and sulfate reduction genes. Close relatives of marine symbionts from the Candidatus Thiodiazotropha genus contributed ~30% and ~20% of all sulfur-oxidizing dsrA and nitrogen-fixing nifK transcripts in stressed roots, respectively. Based on these findings, we propose that the symbiosis between S. alterniflora and sulfur-oxidizing bacteria is key to ecosystem functioning of coastal salt marshes.

Excess cost associated with primary hip and knee joint arthroplasty surgical site infections: a driver to support investment in quality improvement strategies to reduce infection rates.

AIM: To determine the excess costs attributable to surgical site infections (SSI) following primary hip and knee joint arthroplasty at Auckland City Hospital. METHODS: A retrospective case-control study. Cases were patients who developed a SSI following primary hip (THA) and knee arthroplasty (TKA) surgery within 90 days of the procedure. Cases were matched 1:2 with controls; patients whose primary hip and knee arthroplasty procedures were not complicated by infection. Controls were matched for age, gender, date of surgery, type of surgery, and ASA category. The length of stay (LOS) and hospital costs for the initial admission and subsequent readmission for infection were calculated from the clinical costing system at Auckland District Health Board. RESULTS: Eleven cases were identified; 3 following TKA, 7 following THA, and 1 following hemiarthroplasty of the hip. Infections were classified as superficial, 1, joint space, 1, and deep incisional, 9. Five SSI were identified during the initial admission for joint arthroplasty and 6 patients were readmitted with an SSI. Compared to the control patients, SSIs were associated with an excess mean cost of $40,121 and an excess mean LOS of 42 days. CONCLUSIONS: There is a significant increase in LOS and cost associated with SSI following primary THA and TKA at Auckland City Hospital. In addition to the excess cost associated with SSI, there are also opportunity costs resulting from their impact on elective surgical waiting lists. This reinforces the significant positive economic impact a successful strategy to reduce SSIs associated with primary joint arthroplasty procedures will have.

Phosphorus limitation of coastal ecosystem processes.

Primary production in coastal wetlands is conventionally thought to be limited by nitrogen. Although the plant community in a pristine salt marsh was found to be limited primarily by nitrogen availability, the bacterial community in the soil was limited by phosphorus. Hence, in coastal wetlands, and possibly in many ecosystems, individual trophic groups may respond differently to nitrogen and phosphorus loading. Phosphorus limitation of the growth of nitrogen-transforming bacteria will affect carbon fixation, storage, and release mediated by plants, a result that has important implications for ecosystem management.

Use of electrosurgery and lasers in the presence of dental implants.

Use of electrosurgery or laser surgery in the presence of metallic implants has been implicated in generating heat-induced injury to peri-implant bone, with the subsequent loss of osseointegration. Studies involving lasers offer conflicting results, while in the case of the electrosurg, little research has been published supporting or refuting these claims. This study measured local heat effects created by use of a unipolar electrosurgical unit, a bipolar electrosurgical unit, and a neodymium:yttrium-aluminum-garnet (Nd:YAG) laser. Absolute temperature increase was measured during an in vitro uncovering surgical procedure performed with each unit. Analysis of variance for repeated measures was performed. Second, absolute temperature increase for each unit was compared with a theoretical clinical limit of a 10 degrees C increase. The findings suggest that use of the unipolar electrosurgical unit should be avoided, while judicious use of both the bipolar unit or the laser unit should produce temperature profiles well within clinical limits.

Clinical implications of identifying non-B subtypes of human immunodeficiency virus type 1 infection.

Although human immunodeficiency virus type 1 (HIV-1) infection in the United States has predominantly involved subtype B, increasing global travel is leading to wider dissemination of genetically heterogeneous subtypes. While physicians depend on HIV-1 viral load measurements to guide antiretroviral therapy, commonly used molecular assays may underestimate the viral load of patients with non-B subtypes. Nine patients with non-B subtypes of HIV-1 were identified by physicians who suspected a non-B subtype on the basis of a low or undetectable HIV-1 viral load, by the Amplicor HIV-1 Monitor test, version 1.0, in conjunction with either a declining CD4 cell count or history of travel outside the United States. Use of version 1.5 of the Amplicor HIV-1 Monitor test detected a median HIV-1 viral load that was 2.0 log(10) RNA copies/mL higher than was determined with version 1.0. Clinical management was altered in all cases after diagnosis of a non-B-subtype infection. These cases demonstrate that it is critical for physicians to suspect and diagnose non-B subtypes of HIV-1 so that an assay with reliable subtype performance can be used to guide antiretroviral therapy.

Reduction in human immunodeficiency virus patient hospitalizations and nontraumatic mortality after adoption of highly active antiretroviral therapy.

Highly active antiretroviral therapy (HAART) has been recommended for human immunodeficiency virus (HIV)-positive patients with a detectable viral load; it typically consists of two reverse transcriptase inhibitors combined with a protease inhibitor. In 1996, Madigan Army Medical Center began offering HAART to HIV-positive patients with a detectable viral load. We retrospectively reviewed the records of our HIV patients before and after the initiation of HAART to determine the impact of HAART on hospitalizations, mortality, and outpatient pharmacy expenditures. Comparing 1997 with 1994 and 1995, we found a greater than 700% increase in the average expenditure on antiretroviral agents after institution of HAART. At the same time, we found a dramatic reduction in hospitalizations and nontraumatic mortality. Therefore, the increase in expenditures on antiretroviral agents may be offset by a reduction in hospitalizations and mortality.

Exercise dependence among competitive power lifters.

Scores on exercise dependence examined among a sample of 14 competitive power lifters showed higher exercise dependence among lifters than those previously reported for endurance athletes.

Intravenous streptomycin: a useful route of administration.

Streptomycin is an aminoglycoside antibiotic that is indicated for the treatment of tuberculous and nontuberculous infections. Intramuscular injection is the recommended route of administration. There are few reports on intravenous administration of streptomycin. We describe the use of intravenous streptomycin to treat endocarditis due to a strain of Enterococcus faecalis with high-level resistance to gentamicin. Physicians should consider the intravenous route as an alternate method of administering streptomycin.

Sarcoidosis and ELISA for Borrelia burgdorferi.

Lyme disease can be confirmed by detection of IgM and IgG antibodies against the causative pathogen Borrelia burgdorferi. Enzyme-linked immunosorbent assay (ELISA) can be confirmatory within weeks of symptom onset. Sarcoidosis has not previously been reported as one of the disease processes associated with a false-positive ELISA for Lyme disease. In our study, Lyme ELISA was obtained in 25 patients with various degrees of activity of sarcoidosis. ELISA was positive for Lyme disease in only one of these patients. Sarcoidosis may not be one of the diseases that commonly results in a false-positive Lyme ELISA.

Fungemia due to Torulopsis glabrata.

Torulopsis glabrata is a yeast ordinarily considered nonpathogenic. Systemic infection with this yeast occurs in patients who are debilitated, immunosuppressed, diabetic, or receiving multiple antibiotics. We have presented a case of fungemia due to T glabrata in a previously healthy person. The predisposing condition resulting in debility and predisposition to fungemia was major vascular surgery. Treatment with amphotericin B eradicated the fungemia.

Disseminated infection due to Mycobacterium chelonei.

We have presented a case of M chelonei subsp abscessus in an immunocompromised patient. The patient was given antimicrobial therapy, to which the organism appeared sensitive for 4 weeks, but he died because of other medical problems. Repeated negative blood cultures for mycobacteria after the initiation of therapy and a careful postmortem examination suggested that the antimicrobial therapy was effective.

Recurrence of neisserial meningococcemia due to deficiency of terminal complement component.

Recurrent infections with Neisseria meningitidis are attributed to deficiencies of terminal complement components. The serotype most commonly responsible for recurrent N meningitidis infections is serotype Y. We have reported a case of recurrent meningitis due to N meningitidis in a patient who was found to be deficient in the sixth component of complement. Complement deficiencies should be considered in any patient with recurrent infections caused by N meningitidis.

Homeless individuals and drug-resistant tuberculosis in south Texas.

Drug-resistant tuberculosis was found in 21 percent of homeless individuals in New York City between 1982 and 1987. To see if this relationship existed in south Texas, we evaluated all admissions to a Texas Health Department facility with culture-proven tuberculosis. Four hundred forty-three patients were admitted between September 1987 and October 1990. Twenty-six, (5.9 percent) of these patients were identified as homeless. Alcoholism, tobacco abuse, divorce, and unemployment were common demographic characteristics. Six male patients and one female patient (27 percent) had Mycobacterium tuberculosis resistant to one or more antituberculosis drugs. Five were Hispanic, one was white, and one was black. The six male patients had resistance to only one drug, either rifampin or ethambutol. The female patient had resistance to streptomycin, isoniazid, and rifampin. These findings illustrate that drug-resistant tuberculosis exists among homeless individuals in south Texas. As the number of homeless people increases, physicians need to recognize that pulmonary tuberculosis is a frequent infection in this population and that the causal mycobacteria may well be resistant to one or more antituberculosis agents.

Pulmonary tuberculosis in diabetics.

Pulmonary tuberculosis is found predominantly in the lung apices. In diabetics it has been suggested that tuberculosis tended to occur predominantly in the lower lobes. A retrospective chart review was performed of all patients with a diagnosis of diabetes and pulmonary tuberculosis admitted to a health care facility to determine the presenting chest roentgenographic location of tuberculosis. Multiple lobe involvement was the predominant chest roentgenographic finding in both diabetics and nondiabetics with pulmonary tuberculosis. Since tuberculosis and diabetes frequently coexist in the population at risk for tuberculosis, clinicians should suspect tuberculosis in the diabetic with an abnormality on chest roentgenogram. Aggressive diagnostic measures and specific chemotherapy should be given and monitored to treat pulmonary tuberculosis.