Stability of human methanogenic flora over 35 years and a review of insights obtained from breath methane measurements.

BACKGROUND & AIMS: Breath methane measurements reflect the in situ activity of the methanogenic colonic flora. Thirty-five years ago we found that 34% of healthy adult subjects were methane producers (breath methane level >1 ppm above atmospheric methane levels). The current study presents a new survey of breath methane levels designed to determine if the activity of the methanogenic flora has changed over the past 35 years. In addition, we review insights into the methanogenic flora that have resulted from breath methane measurements. METHODS: The end-alveolar breath methane concentrations of 212 healthy adults living in the Minneapolis area were determined via gas chromatography. The influence of sex, age, and bowel movement frequency on methane production was assessed. RESULTS: The findings that 36.4% of participants were methane producers, with a mean methane concentration in these producers of 16.6 ppm, are strikingly similar to the values of 33.6% and 15.2 ppm observed 35 years ago. Neither sex nor age showed a statistically significant relationship to methane production. There was a negative correlation between frequency of bowel movements and breath methane concentration in methane producers. CONCLUSIONS: The activity of the methanogenic flora of healthy adults remained remarkably stable over the past 35 years despite widespread antibiotic use and dietary changes. A literature review revealed that many associations have been shown between methane production and clinical states, but it remains to be determined if methanogens actively influence human physiology or are simply a marker of colonic function.     

Electrocardiographic findings in children with Lyme disease.

The incidence of cardiac involvement in Lyme disease (LD) has been estimated to be 4 to 10% in adults, with conduction and rhythm disturbances noted most frequently. To assess the frequency of electrocardiographic abnormalities in children with LD, we prospectively performed 12-lead electrocardiograms in 32 randomly selected children presenting with LD between May and September 1989. No patient had symptoms of cardiac involvement. Using defined diagnostic criteria, combining symptoms, signs, serology, and residence in or travel to an endemic area, 14 patients were classified as having definite LD and 10 were categorized as probable. The incidence of electrocardiographic abnormalities in the definite group was 29% (4/14), including two patients with 1 degree atrioventricular block, one with left axis deviation, and one with ventricular ectopy. Thirty percent (3/10) of the probable group had abnormal ECGs, including one with ST-T wave abnormalities, one with prominent sinus arrhythmia, sinus bradycardia, and wandering atrial pacemaker, and one with ectopic atrial bradycardia. No patient required cardiac therapy. The incidence of abnormal ECG findings in this group of children with either probable or definite LD was thus 29%, with 1 degree atrioventricular block noted most frequently. When the diagnosis of LD is highly suspected, an electrocardiogram may be a useful screening test for cardiac involvement.     

What is the prognostic value of myocardial perfusion imaging using rubidium-82 positron emission tomography?

OBJECTIVES: The objective was to determine the prognostic value of rubidium-82 (82Rb) positron emission tomography (PET) myocardial perfusion imaging (MPI). BACKGROUND: 82Rb PET MPI accurately diagnoses coronary artery disease (CAD). However, there are limited data evaluating its prognostic value. METHODS: Follow-up (3.1 +/- 0.9 years) was obtained in 367 patients who underwent dipyridamole 82Rb PET MPI. Patients were divided into groups based on their summed stress score (SSS): group I, normal (<4); group II, mild (4 to 7); and group III, moderate (8 to 11) to severe (> or =12). RESULTS: There were significant differences among patients in the 3 SSS groups for hard events (cardiac death and myocardial infarction [MI]) (p < 0.001) and total cardiac events (hard events, revascularization and hospitalization) (p < 0.001). The annual hard events rates were 0.4%, 2.3%, and 7.0% in the normal, mild, and moderate-severe groups, respectively. In adjusted survival models, 82Rb PET SSS was the strongest predictor of total cardiac events and a significant predictor of hard events. Among patients referred for PET after 99mTc single-photon emission computed tomography, the annual total event rate was higher with abnormal versus normal SSS on PET (15.2% vs. 1.3%, p < 0.001). In patients with obesity, the annual total event rate was 11.1% with an abnormal scan and 1.5% with a normal scan (p < 0.001). CONCLUSIONS: This study shows that 82Rb PET MPI has significant prognostic value for predicting cardiac events, including death and MI. It also seems to have prognostic value in patients whose diagnosis remains uncertain after single-photon emission computed tomography MPI and in obese patients. The prognostic value of PET MPI may improve the management of cardiac patients.     

Optimum management of the discharging ear.

Discharge from the ear can be the result of many disease processes. The ear may discharge blood, pus, cerebrospinal fluid (CSF) or wax. Keratosis obturans, stenosis of the external meatus and benign tumours of the external meatus all lead to wax build-up, which may cause recurrent attacks of otitis externa. Malignant tumours, such as basal cell carcinoma, squamous cell carcinoma and tumours of ceruminous gland origin may also present with discharge. Tumours should be excluded by submitting all material removed from the external canal for histological examination. Single or multiple abscesses (known as furuncles) may occur in the hair follicles in the skin of the external acoustic meatus (EAM). Compulsive scratching, hearing aids and foreign bodies placed in the ear predispose to otitis externa, which is also often associated with infection by Pseudomonas aeruginosa, Staphylococcus aureus and faecal organisms. Management may be with aluminium acetate 14%, topical antibiotic/steroid drops, a gauze wick soaked with icthammol 10% in glycerin or polymyxin B sulphate--neomycin sulphate--hydrocortisone acetate cream placed into the EAM and replaced every 24 to 48 hours, or systemic antibiotics according to severity. Malignant (necrotising) otitis externa causes progressive destruction of the temporal bone, and cranial nerve palsies (usually facial first). Treatment is limited debridement of infected bone, accompanied by intravenous aminoglycosides, and local antibiotic treatment and aural cleanout or oral ciprofloxacin. Middle ear conditions causing discharge include acute otitis media, infected grommets, traumatic perforations and chronic suppurative otitis media, as well as tumours of the ear canal skin and middle ear, radiation-induced otitis externa and osteoradionecrosis of the temporal bone, tuberculosis, Langerhans cell histiocytosis, spontaneous or post-traumatic CSF leaks, Wegeners granulomatosis and immune deficiency states. Topical application of aminoglycoside antibiotics to the middle ear of laboratory animals such as rats, guinea pigs and chinchillas causes sensorineural hearing loss, an effect rarely seen clinically in humans. If the external acoustic meatus and tympanic membrane are obscured by discharge cotton buds, microsuction equipment or syringing are used to remove it. It is often useful to initiate treatment (usually with topical drops, wicks or an oral antibiotic) with a provisional diagnosis. A full examination and adequate visualisation of the tympanic membrane must eventually be performed, if necessary under anaesthesia, or else serious progressive conditions may be neglected. The most useful initial investigation is a swab sent for bacteriological assessment; other investigations are usually indicated by clinical findings and the provisional diagnosis.     

Detection of mutations associated with isoniazid and rifampin resistance in Mycobacterium tuberculosis isolates from Samara Region, Russian Federation

High incidence rates of isoniazid-, rifampin-, and multiple-drug-resistant tuberculosis have been reported in countries of the former Soviet Union (FSU). Genotypic (unlike phenotypic) drug resistance assays do not require viable cultures but require accurate knowledge of both the target gene and the mutations associated with resistance. For these assays to be clinically useful, they must be able to detect the range of mutations seen in isolates from the population of tuberculosis patients to which they are applied. Two novel macroarrays were applied to detect mutations associated with rifampin (rpoB) and isoniazid (katG and inhA) resistance. In a sample of 233 isolates from patients in Samara, central Russia, 46.5% of isolates possessed mutations in both the rpoB and the katG (or inhA) genes. Combined results from the macroarrays demonstrated concordance in 95.4 and 90.4% of phenotypically defined rifampin- and isoniazid-resistant isolates, respectively. The contribution of different mutations to resistance was comparable to that reported previously for non-FSU countries, with 90% of rifampin-resistant isolates and 93% of isoniazid resistant isolates due to rpoB531 and katG315 mutations, respectively. The percentage of phenotypically resistant rifampin isolates with no mutations in the rpoB codons 509 to 536 was 4.2%, which was similar to previous reports. Novel macroarrays offer a rapid, accurate, and relatively cheap system for the identification of rifampin-, isoniazid-, and multiple-drug-resistant Mycobacterium tuberculosis isolates.     

Estimation of the rate of unrecognized cross-contamination with mycobacterium tuberculosis in London microbiology laboratories

Isolates from patients with confirmed tuberculosis from London were collected over 2.5 years between 1995 and 1997. Restriction fragment length polymorphism (RFLP) analysis was performed by the international standard technique as part of a multicenter epidemiological study. A total of 2,779 samples representing 2,500 individual patients from 56 laboratories were examined. Analysis of these samples revealed a laboratory cross-contamination rate of between 0.54%, when only presumed cases of cross-contamination were considered, and 0.93%, when presumed and possible cases were counted. Previous studies suggest an extremely wide range of laboratory cross-contamination rates of between 0.1 and 65%. These data indicate that laboratory cross-contamination has not been a common problem in routine practice in the London area, but in several incidents patients did receive full courses of therapy that were probably unnecessary.