Estimates of African, European and Native American ancestry in Afro-Caribbean men on the island of Tobago

BACKGROUND/AIMS:The Tobago Afro-Caribbean population is a valuable resource for studying the genetics of diseases that show significant differences in prevalence between populations of African descent and populations of other ancestries. Empirical confirmation of low European and Native American admixture may help in clarifying the ethnic variation in risk for such diseases. We hypothesize that the degree of European and Native American admixture in the Tobago population is low.METHODS:Admixture was estimated in a random sample of 220 men, from a population-based prostate cancer screening survey of 3,082 Tobago males, aged 40 to 79 years. We used a set of six autosomal markers with large allele frequency differences between the major ethnic populations involved in the admixture process, Europeans, Native Americans and West Africans.RESULTS:The ancestral proportions of Tobago population are estimated as 94.0+/-1.2% African, 4.6+/-3.4% European and 1.4+/-3.6% Native American.CONCLUSIONS:We conclude that Tobago Afro-Caribbean men are predominantly of West African ancestry, with minimal European and Native American admixture. The Tobago population, thus, may carry a higher burden of high-risk alleles of African origin for certain diseases than the more admixed African-American population. Conversely, this population may benefit from a higher prevalence of protective alleles of African origin.

A cross-sectional study of isolates from sputum samples from bacterial pneumonia patients in Trinidad

We determined the frequency of Streptococcus pneumoniae, Haemophilus influenzae,Staphylococcus aureus, and Gram-negative enteric bacteria (GNEB) in pneumonia patients,determined the antibiograms of these pathogens, and investigated the relationship between pneumonia and selected risk factors. Sputum and demographic data were collected from 124pneumonia patients. Sputum was cultured for S. aureus, GNEB, H. influenzae and S. pneumoniae.The disc diffusion method was used to determine resistance to eight antimicrobial agents. Amongthe 124 sputum samples, eight (6.5%) were positive for S. aureus, 15 (12.1%) for GNEB, two(1.6%) for S. pneumoniae and one (0.8%) for H. influenzae. Hospitals, gender, ethnicity, comorbidities and symptoms did not significantly (p > 0.05; ö2) affect the prevalence of these bacteria.GNEB infection was most prevalent (47%) in patients over 70 years old. Gentamicin and levofloxacin were the most effective against these bacteria.

Clustering of cases of mycobacterium fortuitum infection investigated by molecular typing

Organisms of the mycobacterium fortuitum complex are recognised but uncommon causes of pulmonary disease, primary cutaneous disease and a wide spectrum of nosocomial infections. M fortuitum was isolated from 20 patients over a 15 month period, with a apparent clustering of isolates occurring from January to March 1994. The molecular epidemiology of this clustering eas investigated using an arbitrary primer polymerase chain reaction method (AP-PCR). 21 isolates were studied, which yielded 13 distinct profiles. Multiple isolates from a single patient yielded identical profiles. All of seven isolates recovered during the six week period from January to March 1994 shared a common profile which was distinct from all other isolates, suggesting that a single strain was isolated from specimens from all seven patients. The source of this cluster in uncertain. We can find no epidemilogical basis for an episode of cross-infection within the hospital environment, and it is assumed that contamination of the specimens during collection, transport or processing was responsible for the "pseudo-outbreak" of M fortuitum

Quality assurance in relation to mycobacterial sputum samples received and processed at the National Public Health Laboratory, Jamaica, 1st August 1997-31st January 1998, and the effects on patients' treatment

There has been a global increase in the incidence of mycobacterial cases since the advent of HIV and AIDS. This increase has not been seen in Jamaica. This study was done to determine the quality of samples received, at the National Public Health Laboratory, in terms of sputum/saliva and time submitted after collection, and to evaluate if this affected case treatment. Data was retrospectively extracted from bench records at the laboratory and analyzed. Cross checking of laboratory negative and positive cases was done using patients' records ar the National Chest Hospital, to validate laboratory results with clinical diagnosis. Evaluation of treatment of positive cases with respect to sensitivity results was done. Results showed that of the 925 sputum samples submitted 86.6 percent were true sputum samples, submitted mainly from the urban region. Sputum samples were five times more likely to yield positive TB culture results than saliva. There was no statistically significant difference in mycobacteria other than tuberculosis (MOTT)or contamination results between sputum and saliva. With respect to time of arrival, only 412 samples were analyzed due to lack of data. Of these, 56.1 percent of these arrival within one day. Positive TB cultures were no different among sputum (14.3 percent) and saliva (13.3 percent) sample with respect to time of arrival. Contamination rate was slightly higher in samples received >1 day (4.4 percent), to those received within one day (2.2 percent). The treatment of 22 TB positive cases evalusted, corresponded with the sensitivity results, but only one of the three MOTT cases corresponded. The quality of sputum samples received was generally good, and did not significantly affect culture results and patients' treatment. A further study however, needs to be done to evaluate quality assurance and quality control measures in the laboratory (AU)

Quality assurance in relation to mycobacterial sputum samples received and processed at the National Public Health laboratory, 1st August 1997 to 31st January, 1998 and the effect of patients' treatment

There has been a global increase in the incidence of mycobacterial cases since the advent of HIV and AIDS. This increase has not been seen in Jamaica. This study was done to determine the quality of sample received, at the National Public Laboratory, in terms of sputum/saliva and time submitted after collection, and to evaluate if this affected case treatment. Data was retrospectively extracted from bench records at the laboratory and analyzed. Cross checking of laboratory negative and positive cases was done using patients' record at the National Chest Hospital, to validate laboratory results with clinical diagnosis. Evaluation of treatment of positive cases with respect to sensitivity results was done. Results showed that of the 925 sputum submitted 86.6 percent were true sputum samples, submitted mainly from the urban region. Sputum samples were five times more likely to yield positive TB culture results than saliva. There was no statistically significant difference in mycobacteria other than tuberculosis (MOTT) or contamination results between sputum and saliva. With respect to time of arrival, only 412 samples were analyzed due to lack of data. Of these, 56.1 percent of these arrived within one day. Postive TB cultures were no different among sputum (14.3 percent) and saliva (13.3 percent) samples with respect to time of arrival. Contamination rate was slightly higher in samples received > 1 day (4.4 percent), to those received within one day (2.2 percent). The treatment of 22 TB positive cases evaluated, corresponded with the sensitivity results, but only one of the three MOTT cases corresponded. The quality of sputum samples received was generally good, and did not significantly affect culture results and patients' treatment. A further study however, needs to be done to evaluate quality control measures in the laboratory.(AU)

Aspiration in seriously ill patients: a study of amylase in bronchial secretions

Bronchial secretions from 21 patients with moderate to severe chest infections were obtained by transtracheal aspiration. Six seriously ill patients showed greatly increased levels of amylase activity in the bronchial secretions compared with those found in the 15 less ill patients. This amylase was almost certainly derived from oropharyngeal contents and its presence suggests that aspiration may be more common in comatose and semi-comatose patients than is generally appreciated. (Summary)

Insignificance of colonic bacteria in the sputum of patients in a new ICU

Over a 12-month period, 27 percent of patients in a new ICU grew bacterial pathogens from sputum or tracheal cultures. The commonest isolates were Pseudomonas aeruginosa and Klebsiella species. Endotracheal intubation, the length of time intubated, and antimicrobial therapy all predisposed to the isolation of organisms from sputum. No patient developed a gram-negative pneumonia, and there was no case of septicemia associated with a positive sputum culture. The presence of epithelial or pus cells in sputum was unrelated to the culture results. It was concluded that the growth of colonic bacteria from sputum or tracheal aspirates was of little prognostic or clinical significance. No significant common environmental site or cross-infection pathway was identified: sinks were contaminated by patients rather than vice versa. Most sputum isolates were probably endogenous in origin. (AU)

Cigarette smoking and irreversible airways obstruction in the West Indies

Two communities, one in Jamaica and one in Guyana, have been surveyed in order to investigate the relationships between cigarette smoking and respiratory symptoms, and lung function in the West Indies. Cigarette consumption was less than that reported in the United Kingdom, particularly among women. Smoking was associated with cough, phleghm, increases in total lung capacity and residual volume, and reductions in FEV percent, transfer coeffecient (Kco), and aveolar capillary blood volume (Vc). Vital capacity (VC) and the diffusion capacity of the alveolar membranes (Dm) were normal. After allowing for differences in age and tobacco consumption, less cough, phleghm and airways obstruction occurred in the West Indies than has been reported in the United Kingdom. Forty-seven patients in Jamaica with chronic obstructive lung disease were followed for three years. All except six female asthmatics were either current smokers or ex-smokers. Smoking in patients was associated with a similiar but more severe pattern of lung disease to that found in survey subjects with, in addition, reductions in VC, and Dm. In the non-smoking asthmatics Kco, Dm, and Vc were normal. The lung function of these 47 patients was similiar to that reported for UK patients even though both chronic bronchitis and hypercapnia were considerably less common in Jamaica. Emphysema was present in all six patients who died and came to necropsy. It is suggested that in the West Indies emphysema contributes more than bronchitis to airways obstruction in smokers. There was also evidence that subjects of African origin were less susceptible to the emphysema-producing effect of cigarettes than were other ethnic groups (AU)

Tracheobronchomegaly

Over fifty cases of tracheobronchomegaly reported in the literature are reviewed and two new cases are described. The radiological appearances of this rare condition are described and its concomitant occurrence with bronchiectasis is noted. The condition is thought to be due to faulty development of the connective tisssues of the tracheobronchial tree. However, a study of the age of presentation showed that the majority presented in the third or later decades which suggests that it is an acquired rather than a developmental anomaly. (AU)