Influence of tetracycline exposure on tetracycline resistance and the carriage of tetracycline resistance genes within commensal Escherichia coli populations

AIMS

To assess the influence of incremental tetracycline exposure on the genetic basis of tetracycline resistance within faecal Escherichia coli.

METHODS AND RESULTS

Through the adoption of a novel combination of multiple breakpoint selection, phenotypic characterization and the application of a polymerase chain reaction based gene identification system it proved possible to monitor the influence of antibiotic exposure on resistance gene possession. Using tetracycline as a case study a clear hierarchy was revealed between tet genes, strongly influenced by host antimicrobial exposure history.

CONCLUSIONS

The antimicrobial exposure regime under which an animal is produced affects both the identity and magnitude of resistance gene possession of a selected bacterial population within its enteric microflora. Among the ramifications associated with such resistance gene selection is the degree of resistance conferred and the carriage of linked resistance determinants. This selection is applied by exposure to antibiotic concentrations well below recognized minimum inhibitory tetracycline concentration breakpoints widely adopted to characterize bacterial 'susceptibility'.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study confirms the ability of minimal antibiotic exposure to select for the continued persistence of resistance genes within the enteric microflora. It is clearly demonstrated that different antimicrobial regimes select for different resistance genes, the implications of which are discussed.

Methane oxidation and its coupled electron-sink reactions in ruminal fluid

AIMS

This study was conducted to investigate the occurrence of methane oxidation in the rumen, and to identify the electron-sink reaction coupled to the oxidation if it occurred.

METHODS AND RESULTS

Mixed ruminal microbes taken from sheep were incubated with 13CH4. Oxidation of methane, estimated from the flux of 13C to CO2 and microbial cells, occurred, but represented only 0.2-0.5% of the methane produced. Methane oxidation was suppressed by the presence of oxygen, and was also inhibited by 2-bromoethane-sulphonate, and molybdate, but not by tungstate.

CONCLUSION, SIGNIFICANCE AND IMPACT OF THE STUDY

Methane could be oxidized anaerobically in the rumen by reverse methanogenesis in consort with sulphate reduction.

Quality of health services and early postpartum discharge: results from a sample of non-English-speaking women

Few studies have explored the knowledge, perceptions and satisfaction of ethnic women in relation to early obstetric discharge. The aim of this study was to form a profile of Vietnamese mothers who opt for early postpartum discharge, and to identify factors associated with those decisions. Focus group discussions, in-depth interviews and survey questionnaires were utilized to collect information from a sample of 160 mothers. Sixty mothers (38%) opted for early discharge (< 48 h). Factors strongly associated with early discharge were poor comprehension of English (OR=6.58, 95% CI=1.81, 24.02), very low level of education (OR=3.10, 95% CI=1.55, 6.20) and first time mother (OR=2.70, 95% CI=1.15, 4.27). The in-depth interviews identified further factors driving early discharge, including fear and anxiety when having to approach staff for assistance, and perceptions of disempowerment within culturally unfamiliar hospital surroundings. The findings in this study ought to alert administrators and clinicians to possible negative drivers for the choice of early postpartum discharge by Vietnamese mothers.

The Medical Emergency Team: 12 month analysis of reasons for activation, immediate outcome and not-for-resuscitation orders

OBJECTIVE

To describe the reasons for, and immediate outcome following Medical Emergency Team (MET) activation.

METHODS

Retrospective analysis of MET calls in 1998.

RESULTS

There were 713 MET calls to 559 in-patients. Of the 559 patients 252 (45%) were admitted to ICU and 49 (6.9%) died during the MET response. The three commonest criteria for calling the MET were a fall in GCS>2 (n=155); a systolic blood pressure<90 mmHg (n=142) and a respiratory rate>35 (n=109). Cardiac arrests accounted for 61 calls and had an immediate mortality of 59%. The most common MET criterion associated with admission to ICU was a respiratory rate >35. Of patients who received MET calls based only on the 'worried' criterion 16% were admitted to ICU. The MET felt that a not-for-resuscitation order would have been appropriate in 130 cases (23%). NFR orders were documented during 27 of the MET calls.

CONCLUSIONS

The MET system provides objective and subjective criteria by which medical and nursing staff can identify patients who become acutely unwell. A high proportion of these patients will require admission to Intensive Care. The MET system also provides the opportunity to identify patients for whom an NFR order should be considered.

A framework for monitoring maternal and infant health status

The Mother and Infant Network (MINET) Program was established in South Western Sydney Area Health Service(SWSAHS) in 1997. MINET developed and implemented an integrated clinical data network as a key strategy tosupport and inform a Continuum of Care comprising hospital and community based services. There are good datasources within the MINET program. Its scope spans care for mothers and children, which begins with the firstantenatal attendance and ends at school entry.This paper has three interrelated aims: to describe the development of the MINET program; to demonstrate thebenefits of a sustainable Information Culture which can assist an Area Health Services in adopting a health outcomesbased approach to service delivery; and to describe how MINET has the capacity to support Health Services Research.

Acute hospital medical staffing during the night shift

There has been little or no attempt to define the need for 24-hour medical cover, nor its appropriateness in acute hospitals, despite the great cost implications and the question of the quality of that care. This study examined the medical activity during the 'night shift' in an acute hospital. There were an average of 2.59 calls per night, most from the emergency department (247/475) and general wards (108/475). Many calls were related to active resuscitation (88/475) and immediate treatment (83/475). Over 40% (81/286) of patients had to be transferred to a higher level of care, such as an intensive care unit within the hospital. By collecting data on the demands of health care during what amounts to over a third of the hospital's time, it was established that a high level of medical care was required. Appropriate levels of staffing, using junior doctors trained in acute medicine, was able to be provided to match need as determined by these data, and extra staff at higher costs were avoided.

Intra-abdominal hypertension is an independent cause of postoperative renal impairment

HYPOTHESIS

Intra-abdominal hypertension exerts an effect on renal function independent of other confounding variables.

DESIGN

A prospective study of all patients admitted to an intensive care unit following abdominal surgery was undertaken between September 1, 1994, and July 31, 1997, in a single university hospital.

MAIN OUTCOME MEASURES

Intra-abdominal pressure (IAP) was measured every 8 hours (normal IAP, 0-17 mm Hg); 18 mm Hg or higher was considered increased. Forward stepwise logistic regression determined whether intra-abdominal hypertension is an independent cause of renal impairment.

RESULTS

A total of 263 patients (174 after emergency surgery), whose mean +/- SD age was 61.0 +/- 18.7 years and Acute Physiology and Chronic Health Evaluation II score was 14.6 +/- 7.7, were studied. Intra-abdominal pressure was increased in 107 (40.7%) of the 263 patients. Renal impairment occurred in 35 (32.7%) of the 107 patients with intra-abdominal hypertension and in 22 (14.1%) of the 156 with a normal IAP (odds ratio, 1.62-5.42). Using the Wald maximizing model, renal impairment was independently associated with 4 antecedent factors: hypotension (P= .09), sepsis (P = .006), age older than 60 years (P = .03), and increased IAP (P = .004).

CONCLUSIONS

To our knowledge, for the first time in a large clinical study, IAP has been shown to be an independent cause of renal impairment, and it ranks in importance after hypotension, sepsis, and age older than 60 years. Surgeons need to be aware of the importance of intra-abdominal hypertension in patients postoperatively.

Temporary abdominal closure: a prospective evaluation of its effects on renal and respiratory physiology

This study prospectively analyzed outcomes in 49 consecutive patients undergoing temporary abdominal closure (TAC) between 1993 and 1996 at a single university hospital. There were 37 males and 12 females, mean age was 57 years (range, 25-79 years), mean Acute Physiology and Chronic Health Evaluation score was 27 (+7.8 SD), and mean Simplified Acute Physiology II score was 53.0 (+/-15.4). The reason for TAC was decompression in 22 patients, inability to close the abdomen in 10 patients, to facilitate reexploration for sepsis in 8 patients, and multifactorial in 9 patients. After TAC, there was a significant reduction in intra-abdominal pressure from 24.2+/-9.3 to 14.1+/-5.5 mm Hg and improvement in lung dynamic compliance from 24.1+/-7.9 to 27.6+/-9.4 mL/cm H2O (p < 0.05). Although 10 patients experienced brisk diuresis, there was no significant improvement in renal function; in fact, serum creatinine increased. The median length of stay was 35 days (range, 1-232 days). The mean number of abdominal operations after mesh insertion was 2.6+/-2.4. There were 21 deaths, for a standardized mortality rate of 0.80. Although it achieved significant reductions in abdominal pressures and improved lung dynamic compliance, TAC did not result in improved renal function or patient oxygenation.

Psychiatric morbidity following motor vehicle accidents: a review of methodological issues

Motor vehicle accidents (MVAs), even those of a nonserious nature, appear to increase the risk of severe psychiatric morbidity in survivors. The present review examines the evidence indicating the levels of psychiatric morbidity in MVA survivors. Although no consistent profile has emerged, the most commonly reported symptoms are depression, anxiety, irritability, driving phobia, anger, sleep disturbances, and headache, with rates of posttraumatic stress disorder (PTSD) across studies of 0% to 100%. Variability in the type and severity of psychiatric outcomes may be due, in part, to methodological inadequacies in many studies, particularly the use of biased population samples, inclusion of subjects exposed to varied types of accidents, an absence of a clear definition of PTSD, a reliance on clinical judgment rather than the use of objective psychometric measures, the failure to include ratings of injury severity, and the absence of assessments for past exposure to traumatic events or preexisting posttraumatic reactions. The most important concern relates to the use of nonrepresentative samples, usually patients referred for medicolegal assessment in whom issues of compensation are of central importance. Gender and age differences distinguish the compensation group from the general population of MVA survivors, who therefore may also differ in the vulnerability to posttraumatic morbidity. It is argued that more systematic research on unselected subject samples is critical to establish epidemiological data on the true nature and extent of psychiatric morbidity following MVAs.

Quality of life outcomes after intensive care. Comparison with a community group

OBJECTIVE

Compare the health related quality of life of intensive care patients with a community sample.

DESIGN

Self-completed questionnaire posted to a consecutive sample of 238 patients 16 months after discharge from an intensive care unit (ICU) and to a random community sample (n = 242).

SETTING

The Liverpool Hospital is the main referral and teaching hospital in a community of 620,000 people. It has a ten-bed general ICU.

PATIENTS AND PARTICIPANTS

All patients admitted to the ICU over 8 months with a length of stay > or = 24 h and a sample drawn from the community telephone directory.

MEASUREMENTS AND MAIN RESULTS

The self completed questionnaire contained physical and psychosocial health and quality of life (QOL) scales. Analysis of variance indicated that ICU patients were more physically ill and anxiously depressed than the community sample. Sixty-three per cent of patients had not attained full health, were functionally impaired and had a poorer QOL than those patients who had returned to full health and the community. Psychosocial health (apart from anxious depression) was related to the level of perceived physical health rather than to whether or not they had been admitted to the ICU. Those subjects not in full health had poorer interpersonal relationships, less positive attitudes about life, more anxious depression and more suicidal depression.

CONCLUSIONS

ICU patients following discharge have worse perceived health and more anxiety than others in the community. Sixty-three per cent of patients had a poorer QOL and functional health than those who returned to full health and those in the community.

Intraabdominal pressure and gastric intramucosal pH: is there an association?

This study evaluated the potential association between increased intraabdominal pressure (IAP) and abnormally low gastric intramucosal pH (pHi) (</= 7.32) in postoperative patients and assessed its effect on patient outcome. Altogether 73 patients undergoing major abdominal surgery over a 9-month period were studied prospectively. All underwent gastric tonometry and intravesical IAP measurements three time daily. An IAP of >/= 20 mmHg and a pHi of </= 7.32 were considered abnormal. The development of the following complications were also documented: hypotension [mean aortic pressure (MAP) < 80 mmHg], abdominal sepsis, renal impairment, and death. The median APACHE II score was 16 (range 5-34). Twenty-two patients had upper gastrointestinal (GI) surgery, 27 lower GI surgery, and 24 aortic surgery; 44 of these patients underwent emergency surgery. Abnormal pHi (</= 7.32) occurred in 36 patients while on the intensive care unit. Compared to patients with normal pHi, abnormal pHi patients were 11.3 times (3.2-43.5) [odds ratio +/- 95% CI] more likely to have an increased IAP. Abnormal pHi was significantly associated with hypotension (chi2 = 6.8;p = 0.009), sepsis (chi2 = 3.7;p = 0.06), renal impairment (chi2 = 28.3;p = 0. 0000001), relaparotomy (chi2 = 4.1;p = 0.04), and death (chi2 = 9. 7;p = 0.002). This study demonstrated a significant clinical association between increased IAP and abnormal pHi. An abnormally low pHi was associated with poor outcome.