Angiotomografía de la arteria cística en preoperatorio y comorbilidad en colecistectomía laparoscópica por colelitiasis / Angiotomography of the cystic artery in preoperative and comorbidity in laparoscopic cholecystectomy for cholelithiasis

La colecistectomía laparoscópica es el tratamiento de elección de la colelitiasis; sin embargo, se acompaña de comorbilidades y no está exenta de complicaciones mayores que pueden ser letales; la identificación del trígono cistohepático con disección y ligadura de la arteria cística son pasos obligatorios de la cirugía; la identificación de las variaciones de la arteria cística y los conductos biliares pueden minimizar las eventuales complicaciones. Al protocolo preoperatorio se implementó una angiotomografía con Tomógrafo Siemens Somatón Sensation ® de 64 cortes para identificar la arteria cística en pacientes con colelitiasis de la Unidad de Cirugía General del Hospital de Especialidades Teodoro Maldonado Carbo IESS de Guayaquil. Se escogieron 60 pacientes femeninos en forma aleatoria (edades 19-70 años, promedio 44,25 años) y la muestra se dividió en dos grupos de 30; al grupo estudio se aplicó angiotomografía hasta un mes antes de la cirugía y al grupo control se le aplicó el protocolo convencional. Se evaluó morbilidades relacionadas con: hemorragia operatoria por lesión de la arteria cística y en el posoperatorio: infección de herida operatoria, íleo y drenaje. La angiotomografía permitió identificar la arteria cística en el preoperatorio y contribuyó a disminuir comorbilidades que acompañan a la colecistectomía laparoscópica.

Laparoscopic cholecystectomy is the treatment of cholelithiasis of choice; however, it is accompanied by comorbidities and is not exempt from major complications that can be lethal; the identification of the cystohepatic trigone with dissection and ligation of the cystic artery are mandatory steps of surgery; the identification of the variations of the cystic artery and the bile ducts can minimize the possible complications. The preoperative protocol was implemented with an angiotomography with Siemens Somatón Sensation ® 64-slice Tomograph to identify the cystic artery in patients with cholelithiasis of the General Surgery Unit of the Teodoro Maldonado Carbo IESS Specialty Hospital of Guayaquil. 60 female patients were chosen at random (ages 19 -70 years, average 44.25 years) and the sample was divided into two groups of 30; Angiotomography was applied to the study group up to one month before surgery and the conventional protocol was applied to the control group. Morbidities related to: operative haemorrhage due to cystic artery and postoperative injury: operative wound infection, ileus and drainage were evaluated. Angiotomography allowed to identify the cystic artery in the preoperative period and contributed to decrease comorbidities that accompany laparoscopic cholecystectomy.

Anxiety can significantly explain bolus perception in the context of hypotensive esophageal motility: Results of a large multicenter study in asymptomatic individuals.

BACKGROUND: Previous studies have not been able to correlate manometry findings with bolus perception. The aim of this study was to evaluate correlation of different variables, including traditional manometric variables (at diagnostic and extreme thresholds), esophageal shortening, bolus transit, automated impedance manometry (AIM) metrics and mood with bolus passage perception in a large cohort of asymptomatic individuals. METHODS: High resolution manometry (HRM) was performed in healthy individuals from nine centers. Perception was evaluated using a 5-point Likert scale. Anxiety was evaluated using Hospitalized Anxiety and Depression scale (HAD). Subgroup analysis was also performed classifying studies into normal, hypotensive, vigorous, and obstructive patterns. KEY RESULTS: One hundred fifteen studies were analyzed (69 using HRM and 46 using high resolution impedance manometry (HRIM); 3.5% swallows in 9.6% of volunteers were perceived. There was no correlation of any of the traditional HRM variables, esophageal shortening, AIM metrics nor bolus transit with perception scores. There was no HRM variable showing difference in perception when comparing normal vs extreme values (percentile 1 or 99). Anxiety but not depression was correlated with perception. Among hypotensive pattern, anxiety was a strong predictor of variance in perception (R2 up to .70). CONCLUSION AND INFERENCES: Bolus perception is less common than abnormal motility among healthy individuals. Neither esophageal motor function nor bolus dynamics evaluated with several techniques seems to explain differences in bolus perception. Different mechanisms seem to be relevant in different manometric patterns. Anxiety is a significant predictor of bolus perception in the context of hypotensive motility.

The Chicago Classification 3.0 Results in More Normal Findings and Fewer Hypotensive Findings With No Difference in Other Diagnoses.

OBJECTIVES: High-resolution manometry (HRM) is the preferred method for the evaluation of motility disorders. Recently, an update of the diagnostic criteria (Chicago 3.0) has been published. The aim of this study was to compare the performance criteria of Chicago version 2.0 (CC2.0) vs. 3.0 (CC3.0) in a cohort of healthy volunteers and symptomatic patients. METHODS: HRM studies of asymptomatic and symptomatic individuals from several centers of Spain and Latin America were analyzed using both CC2.0 and CC3.0. The final diagnosis was grouped into hierarchical categories: obstruction (achalasia and gastro-esophageal junction obstruction), major disorders (distal esophageal spasm, absent peristalsis, and jackhammer), minor disorders (failed frequent peristalsis, weak peristalsis with small or large defects, ineffective esophageal motility, fragmented peristalsis, rapid contractile with normal latency and hypertensive peristalsis) and normal. The results were compared using McNemar's and Kappa tests. RESULTS: HRM was analyzed in 107 healthy volunteers (53.3% female; 18-69 years) and 400 symptomatic patients (58.5% female; 18-90 years). In healthy volunteers, using CC2.0 and CC3.0, obstructive disorders were diagnosed in 7.5% and 5.6%, respectively, major disorders in 1% and 2.8%, respectively, minor disorders in 25.2% and 15%, respectively, and normal in 66.4% and 76.6%, respectively. In symptomatic individuals, using CC2.0 and CC3.0, obstructive disorders were diagnosed in 11% and 11.3%, respectively, major disorders in 14% and 14%, respectively, minor disorders in 33.3% and 24.5%, respectively, and normal in 41.8% and 50.3%, respectively. In both groups of individuals, only an increase in normal and a decrease in minor findings using CC3.0 were statistically significant using McNemar's test. DISCUSSIONS: CC3.0 increases the number of normal studies when compared with CC2.0, essentially at the expense of fewer minor disorders, with no significant differences in major or obstructive disorders. As the relevance of minor disorders is questionable, our data suggest that CC3.0 increases the relevance of abnormal results.

Normal values of esophageal pressure responses to a rapid drink challenge test in healthy subjects: results of a multicenter study.

BACKGROUND: Multiple water swallow is increasingly used as a complementary challenge test in patients undergoing high-resolution manometry (HRM). Our aim was to establish the range of normal pressure responses during the rapid drink challenge test in a large population of healthy subjects. METHODS: Pressure responses to a rapid drink challenge test (100 or 200 mL of water) were prospectively analyzed in 105 healthy subjects studied in nine different hospitals from different countries. Esophageal motility was assessed in all subjects by solid-state HRM. In 18 subjects, bolus transit was analyzed using concomitant intraluminal impedance monitoring. KEY RESULTS: A virtually complete inhibition of pressure activity was observed during multiple swallow: Esophageal body pressure was above 20 mm Hg during 1 (0-8) % and above 30 mm Hg during 1 (0-5) % of the swallow period, and the pressure gradient across the esophagogastric junction was low (-1 (-7 to 4) mm Hg). At the end of multiple swallow, a postswallow contraction was evidenced in only 50% of subjects, whereas the remaining 50% had non-transmitted contractions. Bolus clearance was completed after 7 (1-30) s after the last swallow, as evidenced by multichannel intraluminal impedance. CONCLUSIONS & INFERENCES: The range of normal pressure responses to a rapid drink challenge test in health has been established in a large multicenter study. Main responses are a virtually complete inhibition of esophageal pressures with a low-pressure gradient across esophagogastric junction. This data would allow the correct differentiation between normal and disease when using this test.

In vitro digestibility, crystallinity, rheological, thermal, particle size and morphological characteristics of pinole, a traditional energy food obtained from toasted ground maize.

Flour obtained from toasted ground maize grains is widely consumed by different ethnic groups of Northern Mexico and Southwest USA as an energy source. In this work the in vitro digestibility, crystallinity, rheological, thermal, particle size distribution and morphological characteristics of toasted ground white and blue maize flours were studied. X-ray diffraction studies showed that the crystallinity content was reduced, but that the hydrolysis rate and the in vitro digestibility of starch were greatly improved by the toasting process. The relative amount of rapidly digestible starch showed an important increase at the expense of resistant starch content reduction. The thermal properties of white maize starch increased slightly, but those of the blue maize starch decreased slightly after toasting. Aqueous dispersions formed with 10% (w/w) flour were heated at 90°C for 5min to induce starch gelling, in order to resemble thin porridges. The dispersed gels exhibited higher elastic modulus (G') than loss modulus (G'') in the linear viscoelastic region, with blue maize dispersions displaying higher moduli magnitudes. At higher shear strain amplitudes, G' decreased but G'' first increased and then decreased (overshoot phenomenon). The effects of toasting on the structure and functionality of maize starch are explained on the basis of limited gelatinization of the granules. The results in this work provide insights for understanding the extensive use of pinole by impoverished ethnic groups, and more recently by high performance ultra-runners and athletes, as an energy food.

Acid hydrolysis of native corn starch: morphology, crystallinity, rheological and thermal properties.

The acid hydrolysis of native corn starch at 35 °C was monitored during 15 days. After this time, the residual solids were about 37.0 ± 3.0%. First-order kinetics described the hydrolysis data, giving a constant rate of kH = 0.18 ± 0.012 days(-1). Amylose content presented a sharp decrement of about 85% and X-ray diffraction results indicated a gradual increase in crystallinity during the first 3 days. SEM micrographs showed that hydrolysis disrupted granule morphology from an initial regular shape to increasingly irregular shapes. Fractal analysis of SEM images revealed an increase in surface roughness. Fast changes in the thermal effects were caused by molecular rearrangements after fast hydrolysis of amylose in the amorphous regions in the first day. Steady shear rate and oscillatory tests showed a sharp decrease of the apparent viscosity and an increase of the damping factor (tan(δ)) caused by amylose degradation.

In vitro digestibility, physicochemical, thermal and rheological properties of banana starches.

Banana starches (BS) were isolated from Enano, Morado, Valery and Macho cultivars. The BS possessed B-type crystallinity and an amylose content varying from 19.32 to 26.35%. Granules had an oval morphology with different major-to-minor axis ratios, exhibiting both mono- and bi-modal distributions and mean particle sizes varying from 32.5 to 45 µm. BS displayed zeta-potential values ranging between -32.25 and -17.32 mV, and formed gels of incipient to moderate stability. The enthalpy of gelatinization of BS affected the crystalline order stability within the granules. In-vitro digestibility tests showed fractions as high as 68% of resistant starch. Rheological oscillatory tests at 1 Hz showed that BS dispersions (7.0%, w/w) exhibited Type III behaviour, attributed to the formation of a continuous phase complex three-dimensional amylose gel reinforced by swollen starch granules acting as fillers. Amylose content and granules morphology were the main factors influencing the BS properties.

Prevalence of healthcare device-associated infection using point prevalence surveys of antimicrobial prescribing and existing electronic data.

This study extended a previously described method for the prevalence of healthcare-associated infection, based on point prevalence surveys of antimicrobial prescribing and electronic data, to estimate the prevalence of device-associated infections. In June 2009, the six-month point prevalence survey of antimicrobial prescribing was carried out in accordance with the European Surveillance of Antimicrobial Consumption Protocol. For patients receiving antimicrobials the presence of devices was recorded. A census on device use was carried out concurrently in the relevant hospitals. We selected patients receiving antimicrobials, started >48h after admission and who had a device, or who were without a device but were receiving antimicrobials for the treatment of bloodstream infection, urinary tract infection, or pneumonia. From existing positive microbiological and radiology reports, these patients were assessed for the presence of device-associated infection according to specified definitions. Of 1354 patients surveyed, 253 (19%) were receiving antimicrobial for treatment; of these, 189 also had devices and 172 (only 13% of all patients surveyed) needed individual assessment for the presence of device-associated infection. It took about 5min per patient to check electronic microbiology and/or radiology reports. Twenty-three patients met the criteria for device-associated infection. The prevalence of catheter-associated urinary tract infection, central-line-associated bloodstream infection, local vascular access infection, and ventilator-associated pneumonia was 3.9%, 3.1%, 3.8% and 11.6%, respectively. This is a simple method, which can be adopted in other hospitals, to estimate the prevalence of device-associated infection using pre-existing data.

Use of anti-infective serial prevalence studies to identify and monitor hospital-acquired infection.

We developed the 'Pragmatic Proxy Protocol' (PPP) to estimate the prevalence of hospital-acquired infection (HAI) by integrating our existing pharmacy serial point prevalence studies of anti-infective prescribing practices with electronic data on microbiological and radiographic markers of infection. Our method was evaluated against the standard Hospital Infection Society/Infection Control Nurses Association Protocol (HIP). In the non-surgical patients, PPP has a sensitivity of 1.00 [confidence interval (CI): 0.70-1.00] and specificity of 0.97 (CI: 0.93-0.99). PPP suggests that for non-surgical patients, the prevalence of HAI using HIP could be underestimated by 42%. PPP takes about two-thirds of the time of HIP (75 vs 106 h) and is at least one-third cheaper. It could easily be adapted to advances in electronic reporting and, with the development of Anti-infective Care Bundles, would increase its sensitivity for the detection of HAI in surgical patients. PPP could be used to increase the frequency of routine HAI surveillance to determine the overall burden of infection and assess the efficacy of intervention strategies in a timely manner allowing rapid, direct feedback and engagement with clinicians.

A case definition for national and international neonatal bloodstream infection surveillance.

OBJECTIVE: Neonatal bloodstream infection (BSI) is a major contributor to mortality, health service costs, and the population burden of lifelong neurodisability. BSI surveillance, an essential component of infection control, requires an unambiguous standardised case definition as variability would invalidate any comparative analyses. In neonates a high proportion of blood cultures yield a mixed growth or skin commensals, principally coagulase-negative staphylococci (CoNS). As this might represent either genuine BSI or contamination, clinical correlates are necessary, but this adds to the difficulty of agreeing an objective, standardised case definition. DESIGN: Utilising data from 26 UK neonatal units, the population prevalence of 12 predefined clinical signs of infection captured daily for 28 days was evaluated. The sensitivity, specificity, odds ratio and positive predictive value of each sign and sequential numbers of grouped signs were determined to develop a predictive model for a positive blood culture. Sandwich estimates of the standard errors of the logistic regression coefficients were used to take account of the correlations between these repeated measures. The model was tested in an independent data set. RESULTS: > or =3 clinical signs had the best predictive accuracy for a positive blood culture (76.2% specificity; 61.5%, 46.9% and 78.2% sensitivity for all positive cultures, cultures yielding CoNS, or a recognised pathogen, respectively). CONCLUSION: This study suggests that a simple case definition for national and international neonatal BSI surveillance is provided by a blood culture yielding a recognised pathogen in pure culture, or a mixed growth or skin commensal plus > or =3 predefined clinical signs.

Risk factors and recommendations for rate stratification for surveillance of neonatal healthcare-associated bloodstream infection.

Neonates are among the most vulnerable patient groups for healthcare-associated infection with multiple endogenous and exogenous risks. Interpretation of neonatal bloodstream infection (BSI) rates requires stratification for case-mix. We assessed 1367 consecutive admissions to a single neonatal unit over a 34-month period. Four intrinsic and seven extrinsic risks were evaluated using Poisson regression analyses both individually and in combination. Nine of the 11 evaluated risk factors were significantly associated with BSI on univariate analyses. The only significant independent risks were parenteral nutrition, whether administered centrally or peripherally [incidence rate ratio (IRR): 14.2; 95% confidence interval (CI): 8.8-22.9; P<0.001], and gestational age <26 weeks (IRR: 2.5; 95% CI: 1.7-3.8; P<0.001). The rate of BSI per 1000 patient-days was 40 times higher in infants with both of these than in infants with neither. If validated in other settings, stratification of neonatal BSI rate by two unambiguous risk factors, parenteral nutrition and birth gestational age <26 weeks, offers a simple method to make meaningful intra- and inter-hospital comparisons.

Infection of the surgical site after arthroplasty of the hip.

We wished to estimate the incidence of surgical-site infection (SSI) after total hip replacement (THR) and hemiarthroplasty and its strength of association with major risk factors. The SSI surveillance service prospectively gathered clinical, operative and infection data on inpatients from 102 hospitals in England during a four-year period. The overall incidence of SSI was 2.23% for 16,291 THRs, 4.97% for 5769 hemiarthroplasty procedures, 3.68% for 2550 revision THRs and 7.6% for 198 revision hemiarthroplasties. Staphylococcus aureus was identified in 50% of SSIs; 59% of these isolates were methicillin-resistant (MRSA). In the single variable analysis of THRs, age, female gender, American Society of Anesthesiologists (ASA) score, body mass index, trauma, duration of operation and pre-operative stay were significantly associated with the risk of SSI (p < 0.05). For hemiarthroplasty, the ASA score and age were significant factors. In revision THRs male gender, ASA score, trauma, wound class, duration of operation and pre-operative stay were significant risk factors. The median time to detection of SSI was eight days for superficial incisional, 11 days for deep incisional and 11 days for joint/bone infections. For each procedure the mean length of stay doubled for patients with SSI. The multivariate analysis identified age group, trauma, duration of operation and ASA score as significant, independent risk factors for SSI. There was significant interhospital variation in the rates of SSI. MRSA was the most common pathogen to cause SSI in hip arthroplasty, especially in patients undergoing hemiarthroplasty, but coagulase-negative Staph. aureus may be more important in deep infections involving the joint.

Adverse impact of surgical site infections in English hospitals.

Between October 1997 and June 2001, 140 English hospitals participating in the surveillance of surgical site infection (SSI) with the Nosocomial Infection National Surveillance Service (NINSS) reported 2832 SSIs following 67 410 surgical procedures in nine defined categories of surgery. Limb amputation had the highest incidence of SSI with 14.3 SSIs per 100 operations. For all categories of surgery, except knee prosthesis (P=0.128), there was a linear increase in the incidence of SSI when the American National Nosocomial Infections Surveillance risk index increased. Superficial incisional SSI was more common than deep incisional and organ/space SSI, and accounted for more than half of all SSIs for all categories of surgery. The postoperative length of stay (LOS) was longer for patients with SSI, and when adjusted for other factors influencing LOS, the extra LOS due to SSI ranged from 3.3 days for abdominal hysterectomy to 21.0 days for limb amputation, and was at least nine days for the other categories. The additional cost attributable to SSI ranged from pound959 for abdominal hysterectomy to pound6103 for limb amputation. Deep incisional and organ/space SSI combined incurred a greater extra LOS and cost than superficial incisional SSI for all categories of surgery, except limb amputation. The crude mortality rate was higher for patients with SSI for all categories of surgery but, after controlling for confounding, only patients with SSI following hip prosthesis had a mortality rate that was significantly higher than those without SSI [odds ratio (OR)=1.8, P=0.002]. However, the adjusted mortality rate for patients with deep incisional and organ/space SSI compared with those without SSI was significantly higher for vascular surgery (OR=6.8, P<0.001), hip prosthesis (OR=2.5, P=0.005) and large bowel surgery (OR=1.8, P=0.04). This study shows that the adverse impact of SSI differs greatly for different categories of surgery, and highlights the importance of measuring the impact for defined categories rather than for all SSIs and all surgical procedures.

Device-related sources of bacteraemia in English hospitals--opportunities for the prevention of hospital-acquired bacteraemia.

Between 1997 and 2001, 17 teaching and 56 non-teaching acute English hospitals conducted hospital-wide surveillance of hospital-acquired bacteraemia (HAB) using a standard protocol drawn up by the Nosocomial Infection National Surveillance Scheme (NINSS). The sources of organisms, the incidence of device-related HAB, and the distribution of HABs from individual device-related sources by specialty and type of hospital were determined for 6,956 HABs in order to identify where resources should best be targeted to reduce these infections. The overall incidence of HAB was higher in teaching than in non-teaching hospitals: 5.39 and 2.83 HABs per 1,000 patients at risk, respectively (P<0.001). Device-related sources were responsible for 52.4 and 43.2% of all HABs in teaching and non-teaching hospitals, respectively (P<0.001), and central lines were the commonest source, causing 38.3% of HABs in teaching versus 22.3% in non-teaching hospitals (P<0.001). In teaching hospitals, general intensive care units (ICUs), haematology, special care baby units (SCBUs), nephrology, and oncology accounted for only 6.1% of the population surveyed, but had the highest incidence of HAB, and contributed 47.8% of 2091 HABs and 56.9% of 1,095 device-related bacteraemias. Of 623 device-related bacteraemias in these high-risk specialties, 554 (88.9%) were from central lines. Thus, in teaching hospitals, resources should be targeted primarily at the prevention of central line-related bacteraemia in these five high-risk specialties, and the surveillance should include data on central line use. In non-teaching hospitals, nearly two thirds (63.3%) of 4,865 HABs and 60.7% of 2,103 device-related bacteraemias were from a few specialties with a low incidence of bacteraemia, but large numbers of patients, namely general medicine, general surgery, geriatric medicine and urology. These specialties accounted for 50.5% of the population surveyed. Central lines were the most common source of bacteraemia in general medicine and surgery, and together accounted for 23.3% of all device-related bacteraemias. However, in geriatric medicine and urology, central line sources were infrequent, accounting for only 1.7% of all device-related bacteraemias. On the other hand, bacteraemia from catheter-associated UTI were common in all these four specialties accounting for 20.9% of all device-related bacteraemias. Thus, in non-teaching hospitals, resources should be targeted primarily at these low-risk specialties and surveillance should include, at least, bacteraemia from central lines and from catheter-associated UTI. Further benefit can be obtained by including central line-related bacteraemias from general ICU and haematology patients, as they contributed 17.0% of all device-related bacteraemias in non-teaching hospitals.

A user evaluation of the Nosocomial Infection National Surveillance System: surgical site infection module.

The Nosocomial Infection National Surveillance Scheme (NINSS) enables hospitals in England to undertake surveillance of healthcare associated infection, compare their results with national aggregated data, and use the information to improve patient care. A surgical site infection (SSI) module was introduced in 1997, and participation has increased steadily since its inception. This survey was undertaken to assess the views of users on the current service, and how the module should be developed to best meet their needs and resources. Survey forms were sent to infection control teams (ICTs) at the 113 hospitals that had participated at any time during the first three years of the programme. The response rate was 90% (102). The views of users were generally very positive and indicated considerable support for the approach to this type of surveillance. The ability to compare hospital infection rates with national data, the availability of standardized surveillance methods, and centralized data analysis and report production were key reasons for participation for over 80% of users. Most did not wish to see any major changes made to the protocol, although more than a third of users suggested additional data items. Overall, users were satisfied with both the content and timescale for receipt of feedback reports, and 77% disseminated them to at least three groups of clinicians and managers. The majority of ICTs (89%) gave the results directly to the surgeons. For some users (29%) it was too early to assess the value of the surveillance. Of the remainder, although results provided evidence of good performance for some, 46% identified high rates of SSI in one or more groups of surgical patients. In about two-thirds of these hospitals, a review or change in clinical practice was initiated as a result. Three main areas for development were identified: an extended range of surgical procedures, post-discharge surveillance and improved local data collection and analysis systems. Users said they would also like training in handling and interpreting surveillance data. These needs should be addressed in order to ensure the continuing success of national surveillance.

Surveillance of hospital-acquired infection in England, Germany, and The Netherlands: will international comparison of rates be possible?

Three national surveillance systems for nosocomial infection have been developed independently and implemented successfully in England, Germany, and The Netherlands. All three are based on the American National Nosocomial Infections Surveillance System and have adopted a surveillance strategy that is targeted at specific infections or groups of patients for limited time periods. Case-finding methods, the minimum data set, and analysis of data are similar and could be standardized easily. Resolution of the differences in the definitions of infection, the study population, and follow-up should make possible the international comparison of infection rates. Such comparisons may identify differences in healthcare practices between countries and suggest areas for improvement.

Risk factors for developing clinical infection with methicillin-resistant Staphylococcus aureus (MRSA) amongst hospital patients initially only colonized with MRSA.

In hospital outbreaks of methicillin-resistant Staphylococcus aureus (MRSA) many patients are initially colonized without infection. The reasons why some progress to infection while others do not are not known. A cohort of 479 hospital patients, initially only colonized with MRSA, was followed prospectively for the development of MRSA infection. Risk factors for progression to infection were assessed using Cox proportional hazards survival analysis. Fifty-three patients (11.1%) developed 68 MRSA infections. Intensive care setting, administration of three or more antibiotics, ulcers, surgical wounds, nasogastric or endotracheal tubes, drains, and urinary or intravenous catheterization were all associated with increased rates of MRSA infection. Multivariate analysis showed that intensive care patients, compared with medical patients, had a higher rate of developing MRSA infection within the first four days of admission, with a hazard ratio of 26.9 (95% CI 5.7-126). Surgical wounds, pressure ulcers and intravenous catheterization were also independent risk factors, with hazard ratios (and 95% CI) of 2.9 (1.3-6.3); 3.0 (1.6-5.7) and 4.7 (1.4-15.6), respectively. These findings suggest that, during an MRSA outbreak, clinical infection would be reduced if surgical and intensive care patients received priority for the prevention of initial colonization with MRSA. Prevention of pressure ulcers, and strict aseptic care of intravenous catheters and surgical wounds would also reduce the development of MRSA infection. Since early treatment with vancomycin is known to reduce the mortality, patients colonized with MRSA who also have one or more of these risk factors may warrant empirical vancomycin therapy at the earliest suggestion of infection.

Prospective study of infection, colonization and carriage of methicillin-resistant Staphylococcus aureus in an outbreak affecting 990 patients.

In the three years between November 1989 and October 1992, an outbreak of methicillin-resistant Staphylococcus aureus (MRSA) affected 990 patients at a university hospital. The distribution of patients with carriage, colonization or infection was investigated prospectively. Nosocomial acquisition was confirmed in at least 928 patients, 525 of whom were identified from clinical specimens as being infected (n = 418) or colonized (n = 107) by MRSA. An additional 403 patients were identified from screening specimens, of whom 58 subsequently became infected and 18 colonized. Screening of the nose, throat and perineum detected 98% of all carriers. Of the 580 infections in 476 patients, surgical wound, urinary tract and skin infections accounted for 58% of the infections. Of the 476 infected patients, death was attributable to MRSA infection in 13%. Colonization with MRSA was found in 127 patients and 42% of 165 colonized sites were the skin. Auto-infection from nasal carriage or cross-infection, probably via staff hands, seemed to be the most common mode of acquisition of MRSA infections.