Penicillin-Binding Protein 5/6 Acting as a Decoy Target in Pseudomonas aeruginosa Identified by Whole-Cell Receptor Binding and Quantitative Systems Pharmacology

The β-lactam antibiotics have been successfully used for decades to combat susceptible Pseudomonas aeruginosa, which has a notoriously difficult to penetrate outer membrane (OM). However, there is a dearth of data on target site penetration and covalent binding of penicillin-binding proteins (PBP) for β-lactams and β-lactamase inhibitors in intact bacteria. We aimed to determine the time course of PBP binding in intact and lysed cells and estimate the target site penetration and PBP access for 15 compounds in P. aeruginosa PAO1. All β-lactams (at 2 × MIC) considerably bound PBPs 1 to 4 in lysed bacteria. However, PBP binding in intact bacteria was substantially attenuated for slow but not for rapid penetrating β-lactams. Imipenem yielded 1.5 ± 0.11 log10 killing at 1h compared to <0.5 log10 killing for all other drugs. Relative to imipenem, the rate of net influx and PBP access was ~ 2-fold slower for doripenem and meropenem, 7.6-fold for avibactam, 14-fold for ceftazidime, 45-fold for cefepime, 50-fold for sulbactam, 72-fold for ertapenem, ~ 249-fold for piperacillin and aztreonam, 358-fold for tazobactam, ~547-fold for carbenicillin and ticarcillin, and 1,019-fold for cefoxitin. At 2 × MIC, the extent of PBP5/6 binding was highly correlated (r2 = 0.96) with the rate of net influx and PBP access, suggesting that PBP5/6 acted as a decoy target that should be avoided by slowly penetrating, future β-lactams. This first comprehensive assessment of the time course of PBP binding in intact and lysed P. aeruginosa explained why only imipenem killed rapidly. The developed novel covalent binding assay in intact bacteria accounts for all expressed resistance mechanisms.

The morbidity spectrum seen by general practitioners in South Africa

Information was obtained from a survey of a representive sample of 8% of the medical practitioners in South Africa in 1985. Each practitioner recorded all reasons for contact, diagnoses, whether a contact was new or a repeat, and demographic details of the patients over a 1-week period. Tables are presented only for general practitioners for contact rates of 70 causes of morbidity (ICD abridged list) as well as a chronicity index for each condition (the ratio of repeat to new contacts for that condition). Acute respiratory infections and diseases of the genito-urinary system were the most common reasons for contact, while diabetes mellitus was the condition with the highest chronicity.

Urbanisation and women's health in Khayelitsha. Part II. Health status and use of health services

A study was conducted among women in Khayelitsha to determine the relationship between urbanisation, health status and use of health services; 722 households were visited, and 659 female respondents provided information on acute and chronic illness for the 3,229 individuals who were members of their households. In addition, they provided information concerning their reproductive health, AIDS awareness, knowledge of cervical smears and use and knowledge of health services. Acute illness was reported for 4.3% of the study population, the commonest complaints being diarrhoea, abdominal pain and upper respiratory infections; 4.4% reported chronic illness, the commonest complaints being hypertension and tuberculosis; 16.2% of women reported gynaecological illness; 86% had of heard of AIDS (although their knowledge of transmission and prevention was poor); and 45% had heard of cervical smears. Patterns of illness and knowledge and use of health services vary in the different areas of residence of Khayelitsha. This appears to be related to urbanisation, age, and environmental and socio-economic factors.

Urbanisation and women's health in Khayelitsha. Part I. Demographic and socio-economic profile

Demographic and socio-economic data and information on migration patterns and urban/rural links was collected from 722 households in the formal housing area and the serviced and the unserviced site areas of Khayelitsha; 659 women and 61 men were interviewed. Thirty-eight per cent of the population were aged under 15 years and 77% under 35 years. There was a predominance of females in the 5-35-year age group. There was a mean of 4.9 persons per household, and 93.5% of sites contained 1 dwelling. Of the 659 female respondents, 7% had received no formal education, 39% had primary school education, and 54% had secondary school education. Unemployment among women was 45%. Domestic service accounted for 66.2% of formal employment. Of all women 86% were unskilled, 71.9% had been born in a 'homeland', and 69.7% had migrated to an urban area before 1985. Ties to the rural areas were strong, particularly in the 'shack' areas. 'New arrivals' to an urban area were young, mostly unemployed, and lived in the worst environmental conditions. In the unserviced 'shack' areas, 47.5% of women had migrated to an urban area in the last 5 years. There are important target areas for a study of the health effects of urbanisation and for possible interventions. This study tends to confirm the 'quadruple' oppression of women in Khayelitsha, on the basis of race, social class and gender and as new arrivals in an urban environment.

The epidemiology of hypertension in family practice in Cape Town

A prevalence study of hypertension in 8 family practices in low socio-economic areas of Cape Town examined 1,046 patients over the age of 15 years. The crude prevalence rate of hypertension was 20.26%. There was no significant sex difference. Systolic pressure, diastolic pressure and hypertensive status increased with age and body mass index (BMI). There were complex relationships with regard to sex in that the female sex was predictive of hypertensive status after the age of 45 years unexplained by differences in BMI. After adjusting for age, BMI and sex differences, widowhood, poor education, obesity, a family history of hypertension or stroke and a past history of hypertension were significant predictors of hypertensive status. Smoking status, occupational social class or property ownership were not predictive. Fifty-one per cent of hypertensive subjects were treated. Of those receiving treatment, 30% were controlled resulting in a control prevalence of only 18%. Younger male subjects were better controlled by treatment. A strong need for improved diagnosis and treatment of hypertension in family practice exists in this region.

The relationship between the hardness of treated water and cardiovascular disease mortality in South African urban areas

A number of studies carried out in other countries have shown the existence of negative correlations between cardiovascular disease mortality and the hardness of water supplies. A study here showed negative correlation (P less than 0.10) between cardiovascular disease mortality for the South African urban white population and total water hardness (equivalent calcium carbonate mg/l). Negative correlations were also found to exist with the hardness-associated factors potassium (P less than 0.05), sulphate (P less than 0.05) and chloride (P less than 0.05) and manganese (P less than 0.10). The results are described in terms of existing studies and a number of local problems have been identified and discussed.

Birth defects surveillance. A pilot system in the Cape Peninsula

A pilot birth defects surveillance system was established in 1982 as part of an epidemiological baseline study pertaining to potential changes in water quality in the Cape Peninsula. The methodology used for reporting birth defects for two information systems, one hospital-based and the other population-based, utilizing statutory notifications of births, is described. Preliminary birth defect rates by cause are presented for a hospital-based system and are consistent with rates reported internationally. The system based on statutory notifications showed gross under-reporting.

Health aspects of the use of recycled water in Windhoek, SWA/Namibia, 1974-1983. Diarrhoeal diseases and the consumption of reclaimed water

The introduction of the use of reclaimed water in Windhoek, SWA/Namibia, prompted an epidemiological study to assess the health effects, if any, of its consumption. Analysis of more than 15,000 episodes of diarrhoeal disease during the period August 1976-March 1983 showed that their incidence in whites of similar socio-economic status was marginally lower in persons supplied with reclaimed water than those with water from conventional sources. Incidence rates were significantly higher in blacks and in coloureds, all of whom received conventional water only. Age-specific incidence rates in children of the various ethnic groups also showed differences characteristically associated with socio-economic stratification. It is concluded that the consumption of reclaimed water does not increase the risk of diarrhoeal diseases caused by waterborne infectious agents.

Morbidity patterns from general practice in Cape Town. A pilot study

A pilot survey of morbidity patterns reflected in general practice was undertaken by a panel of physicians in Cape Town during 1984-1985. Acute upper respiratory tract infections, bronchitis and bronchiolitis were the commonest reasons for contact. A definite pattern of contacts by day of week was noted. The age distribution of the contacts closely matched that of the suburb in which the practice was situated.

Variations in mortality of the coloured, white and Asian population groups in the RSA, 1978-1982. Part V. Hypertensive diseases

An analysis was undertaken of mortality from hypertensive disease in the RSA between 1978 and 1982 among whites, coloureds and Asians. The age-specific mortality rates for each group are presented and comparisons are also made between these groups based on age-standardised mortality rates. As with a similar study undertaken for the period 1969-1971, marked variations are seen between the various population groups. The rates for Asians exceeded those for coloureds substantially, and both these groups had far higher rates than whites. These results demonstrate an interesting variation when compared with mortality from ischaemic heart disease and recent prevalence studies of hypertension. The possibility that this variation is due to better control of hypertension in whites or is a result of a different ratio of risk factors in each group studied is considered.

Variations in mortality of the coloured, white and Asian population groups in the RSA, 1978-1982. Part VI. Ischaemic heart disease

An analysis of ischaemic heart disease (IHD) mortality for the period 1978-1982 showed markedly different rates for the Asian, white and coloured population groups in the RSA. Age-specific and age-standardised rates for Asians were in general considerably higher than those for whites, and did not show the marked decline with time observed in rates for whites. Although coloureds were seen to have considerably lower age-standardized rates than Asians or whites of the same sex, an increase in the age-standardised rates for coloured males over a 10-year period and a slight decrease among females suggested that rates for coloureds may be in the process of approaching those for the other groups. The observed decline in IHD rates among whites of both sexes suggests that preventable major risk factors may be coming under control, apparently to a greater extent in this group than among Asians or coloureds.

Variations in mortality of the coloured, white and Asian population groups in the RSA, 1978-1982. Part IV. Respiratory diseases

Respiratory diseases are major causes of death in South Africa. The reported mortality rates (MRs) for: (i) pneumonia and influenza; (ii) chronic obstructive lung disease and allied conditions; (iii) pulmonary tuberculosis; and (iv) carcinoma of the lung and bronchus over a 5-year period are examined in relation to age, sex, ethnic group and year. Such data have not previously been reported in South Africa. MRs for all respiratory diseases (except lung carcinoma) were substantially higher in coloureds than in whites or Asians. In each ethnic group and for each disease category, MRs for males were higher than for females, especially in those over the age of 24 years. For all, except lung carcinoma, MRs were highest at the extremes of life. Changes in respiratory disease MRs over the 5-year period were examined by calculating the age standardised MRs for each condition in each of the 5 years. There was a clear decline in the MR for pneumonia over this period in all groups. The MR for chronic obstructive pulmonary disease rose in all groups, except Asian females. Similarly, the MR for carcinoma increased in all groups, except white females. The MR for tuberculosis was highest in coloured males (10 times greater than in Asian males and 100 times greater than in white females). The pattern of respiratory disease MRs in white South Africans is very similar to that in the USA, whereas in coloureds MRs for infectious diseases remain high and are added to by the burden of cigarette smoking-related deaths.

Variations in mortality of the coloured, white and Asian population groups in the RSA, 1978-1982. Part II. Cerebrovascular disease

An analysis was undertaken of mortality from cerebrovascular disease in the RSA between 1978 and 1982 in whites, coloureds and Asians. This article details the age-specific mortality rates for each group and also comparisons between groups based on age-standardised mortality rates. Marked differences are seen between the various population groups, the rates for Asians and coloureds (particularly females) far exceeding that for whites. Comparison of these data with those published previously by Wyndham suggest that while mortality from this cause may be falling among whites and Asians, the rate is remaining relatively static in the coloured population.

Variations in mortality of the coloured, white and Asian population groups in the RSA, 1978-1982. Part I. All causes

Previous reports, based largely on the 1970 census and the 8th revision of the International Classification of Diseases, (ICD-8) have suggested that marked differences in mortality exist between population groups in the RSA. In this article the ICD-9 classification of causes of death and 1980 census are used to assess whether the trends have continued through to the present time. Total mortality data in the RSA for whites, coloureds and Asians for the 5-year period 1978-1982 are presented. The 1980 national census provided the denominator population data. Annual age- and sex-specific mortality rates were higher for coloureds than for whites or Asians, the differences being most marked in childhood. There appears to have been little change in total standardised mortality rates among whites over the 5-year period, while increases have occurred among coloureds of both sexes and among Asian males. Analysis of proportional mortality stresses the relatively large proportion of deaths accounted for by external causes and infections among coloureds and by cardiovascular diseases among whites and Asians. There is an urgent need for the health services to take note of these data in order to provide for the varied needs of the population.

Variations in mortality of the coloured white and Asian population groups in the RSA, 1978-1982. Part III. Rheumatic heart disease

An analysis was undertaken of mortality from rheumatic heart disease in the RSA between 1978 and 1982 in whites, coloureds and Asians. This article details the age-specific mortality rates (MRs) for each group and also comparisons between groups based on age-standardised MRs. The rates for Asians and coloureds markedly exceed those for whites, particularly in the lower age groups (under 45 years).

The prevalence of locomotor disability and handicap in the Cape Peninsula. Part I. The coloured population of Bishop Lavis

A door-to-door survey to identify the locomotor disabled was carried out on 33.35% of the so-called coloured population in a low socio-economic area of the Cape Peninsula (9112 people). The prevalence rate of locomotor disability was 11.2/1000. The main causes of disability were illness (44.1%) and trauma (41.2%); the former resulted mostly from cerebrovascular accidents (15.7%) and poliomyelitis (15.7%). Of the disabled persons 11.8% were 15 years of age or less, 57.8% between the ages of 16 and 59 years and 30.4% were more than 60 years. Of those in the working-age group 15% were employed. Few of the unemployed had hobbies or interests or had any contact with health or social services.

The prevalence of locomotor disability and handicap in the Cape Peninsula. Part II. The black population of Nyanga

A door-to-door survey to identify the locomotor-disabled was carried out on 8.5% of the population of a black residential area of the Cape Peninsula (2072 people). The prevalence rate of locomotor disability was 18.3/1000; causes of disability related to illness (36.8%), trauma (31.6%) and congenital factors (23.7%). The main illnesses described were cerebrovascular accidents (26.1%) and poliomyelitis (21.7%). Persons aged 15 years or less constituted 18,4% of the disabled, while 42.1% were aged 16-59 years and 39.5% 60 years or more. Although many of the disabled individuals identified could move about independently, the proportion bedridden was high (15.8%). At the time of the survey 13.3% of adults were working and 51.1% of children over 6 years old attended school. Eighty per cent had no contact with health services.

The prevalence of locomotor disability and handicap in the Cape Peninsula. Part III. The white population of Fish Hoek

A door-to-door survey to identify the locomotor-disabled was carried out on 24.2% of the population living in a white middle-class residential area of the Cape Peninsula (2391 people). This coastal resort is a popular place for retirement and has a large elderly population (23.3%). The prevalence rate of locomotor disability was 13/1000. Illness caused 74.2% of the disability, and in 34.5% of cases this was identified as arthritis. Most of the disabled were aged 60 years or more (77.4%), while 22.6% were 16-59 years old. Fifty per cent of those in the working-age group were employed; one-third competed in the open labour market and the rest were in sheltered employment. Few people were in contact with health, geriatric or social services.

Arthropod-borne virus zoonosis surveillance in the Cape Province: 1. Prospective serological investigations for virus activity in the Beaufort West and Middelburg Districts during 1981

In addition to the routine sero-epidemiological surveillance for arthropod-borne viral zoonoses in the Cape Province carried out by the Department of Medical Microbiology and State Health Department of Virology laboratory, we conducted a prospective serological investigation for virus activity during 1981 in two districts of the Province, namely the Beaufort West and Middelburg districts, which experienced heavy rainfall during the first two months of that year. The approach used was to obtain paired serum samples from identified domestic stock representative of several species from 2-5 months apart and to test them for haemagglutination inhibition antibodies to Rift Valley fever, Wesselsbron and Middelburg virus antigen preparations in order to ascertain, as an indication of viral activity, whether changes in antibody levels occurred between the collection dates. The results indicated that there was probable activity of Rift Valley fever virus and activity of Wesselsbron virus (or related flaviviruses) and Middelburg virus (or related alphaviruses) in the Karoo between the middle of February and the end of July 1981. Despite this activity and heavy rainfall registered at meteorological stations in both the Beaufort West and Middelburg districts as well as general reports of heavy rainfall and considerable mosquito activity over widespread areas of the Karoo, Eastern and S.W. Cape Province, there were no epizootics or epidemics of overt arthropod-borne zoonotic viral disease in the province during 1981.

Smoking habits of nurses

There is little debate as to the harmful effects of cigarette smoking on health. Most health workers advise their patients to cease the practice. The impact of the advice is however diluted if it is seen to be ignored by the professionals themselves. As nurses play an increasing role in all levels of health care a survey was undertaken to investigate the smoking habits of two groups of nurses - those operating within the community and those working in institutions.

Coping with chronic illness. Part II. Cerebrovascular accidents

A survey was undertaken to investigate the fate after discharge of 41 patients admitted to Groote Schuur Hospital, Cape Town, after a cerebrovascular accident. The period of hospitalization, functional capacity after discharge and support received from community-based support agencies were analysed. Major deficiencies in the long-term management of such patients are stressed.

Coping with chronic illness. Part I. Locomotor disability

A survey was undertaken to investigate the ability of 104 subjects with locomotor disability to cope in their homes. Factors which might affect coping, such as age, race, sex and type of disease, were assessed. Note was taken of support received from community-based organizations, ability to work and source of income. The majority of the subjects appeared to be isolated from health personnel after discharge from hospital and to be restricted to their homes. The deficits in the local health services which contributed to this situation are stressed.

Hepatic complications of antituberculosis therapy revisited

Since 1973, when the incidence and pattern of adverse reactions to antituberculosis therapy were described by Rossouw and Saunders, para-amino-salicylic acid, the major cause of drug-induced hepatitis, has been withdrawn from the regimen used in Cape Town and replaced with pyrazinamide (PZA). Our study in the same hospital indicates that although the substitution has resulted in a significant reduction in the incidence of all side-effects (4,1% v. 9%; P less than 0,001), the incidence of hepatitis is unchanged (0,3%). PZA is currently the major cause of hepatitis associated with antituberculosis therapy.