International Validation of a Methicillin-Resistant Staphylococcus aureus Risk Assessment Tool for Skin and Soft Tissue Infections

INTRODUCTION

To promote judicious prescribing of methicillin-resistant Staphylococcus aureus (MRSA)-active therapy for skin and soft tissue infections (SSTI), we previously developed an MRSA risk assessment tool. The objective of this study was to validate this risk assessment tool internationally.

METHODS

A multicenter, prospective cohort study of adults with purulent SSTI was performed at seven international sites from July 2016 to March 2018. Patient MRSA risk scores were computed as follows: MRSA infection/colonization history (2 points); previous hospitalization, previous antibiotics, chronic kidney disease, intravenous drug use, human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS), diabetes with obesity (1 point each). Predictive performance of MRSA surveillance percentage, MRSA risk score, and estimated MRSA probability (surveillance percentage adjusted by risk score) were quantified using the area under the receiver operating characteristic curves (aROC) and compared. Performance characteristics of different risk score thresholds across varying baseline MRSA prevalence were examined.

RESULTS

Two hundred three patients were included. Common SSTI were wounds (28.6%), abscess (25.1%), and cellulitis with abscess (20.7%). Patients with higher risk scores were more likely to have MRSA (P < 0.001). The MRSA risk score aROC (95%CI) [0.748 (0.678-0.819)] was significantly greater than MRSA surveillance percentage [0.646 (0.569-0.722)] (P = 0.016). Estimated MRSA probability aROC [0.781 (0.716-0.845)] was significantly greater than surveillance percentage (P < 0.001) but not the risk score (P = 0.192). The estimated negative predictive value (NPV) of an MRSA score ≥ 1 (i.e., a score of 0) was greater than 90% when MRSA prevalence was 30% or less.

CONCLUSION

The MRSA risk score and estimated MRSA probability were significantly more predictive of MRSA compared with surveillance percentage. An MRSA risk score of zero had high predictive value and could help avoid unnecessary empiric MRSA coverage in low-acuity patients. Further study, including impact of such risk assessment tools on prescribing patterns and outcomes are required before implementation.

A multi-centre clinical evaluation of reactive oxygen topical wound gel in 114 wounds

OBJECTIVE

This article reports the outcomes of the use of Surgihoney RO (SHRO), topical wound dressing in a multi-centre, international setting. The aims were to explore the clinical effects of SHRO, including a reduction in bacterial load and biofilm and improvement in healing in a variety of challenging non-healing and clinically infected wounds.

METHOD

This was a non-comparative evaluation, where both acute and chronic wounds with established delayed healing were treated with the dressing. Clinicians prospectively recorded wound improvement or deterioration, level of wound exudate, presence of pain, and presence of slough and necrosis. Analysis of this data provided information on clinical performance of the dressing. Semi-quantitative culture to assess bacterial bioburden was performed where possible.

RESULTS

We recruited 104 patients, mean age 61 years old, with 114 wounds. The mean duration of wounds before treatment was 3.7 months and the mean duration of treatment was 25.7 days. During treatment 24 wounds (21%) healed and the remaining 90 (79%) wounds improved following application of the dressing. No deterioration in any wound was observed. A reduction in patient pain, level of wound exudate and in devitalised tissue were consistently reported. These positive improvements in wound progress were reflected in the wound cultures that showed a reduction in bacterial load in 39 out of the 40 swabs taken. There were two adverse events recorded: a stinging sensation following application of the dressing was experienced by 2 patients, and 2 elderly patients died of causes unrelated to the dressing or to the chronic wound. These patients' wounds and their response to SHRO have been included in the analysis.

CONCLUSION

SHRO was well tolerated and shows great promise as an effective potent topical antimicrobial in the healing of challenging wounds.

DECLARATION OF INTEREST

Matthew Dryden has become a shareholder in Matoke Holdings, the manufacturer of Surgihoney RO, since the completion of this study. Keith Cutting is a consultant to Matoke Holdings.

In vitro activity of an engineered honey, medical-grade honeys, and antimicrobial wound dressings against biofilm-producing clinical bacterial isolates

OBJECTIVE

Honey is recognised to be a good topical wound care agent owing to a broad-spectrum of antimicrobial activity combined with healing properties. Surgihoney RO (SH1) is a product based on honey that is engineered to produce enhanced reactive oxygen species (ROS) and has been reported to be highly antimicrobial. The objective was to investigate the ability of the engineered honey and its comparators to prevent biofilm formation in vitro.

METHOD

We tested the ability of three medical-grade honeys SH1, Activon manuka honey (MH) and Medihoney manuka honey (Med), alongside five antimicrobial dressings (AMDs) to prevent the formation of biofilms by 16 isolates. Honeys were serially double diluted from 1:3 down to 1:6144 and the lowest dilution achieving a statistically significant reduction in biomass of at least 50%, compared with untreated controls, was recorded.

RESULTS

Although all the honeys were antibacterial and were able to prevent the formation of biofilms, SH1 was the most potent, with efficacy at lower dilutions than the medical honeys for five isolates, and equivalent dilutions for a further six. Additionally, SH1 was superior in antibacterial potency to three commercially available AMDs that contain honey.

CONCLUSION

SH1 is effective at preventing bioflms from forming and is superior to medical honeys and AMDs in in vitro tests.

DECLARATION OF INTEREST

Surgihoney RO was provided free of charge for testing by Matoke Holdings, UK and the hospital pharmacy provided the other honeys and dressings. This paper presents independent research funded by the National Institute for Health Research (NIHR). The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health.

Procalcitonin levels predict infectious complications and response to treatment in patients undergoing cytoreductive surgery for peritoneal malignancy

BACKGROUND

Cytoreductive-surgery for peritoneal-malignancy (PM) involves extensive intra-abdominal surgery and a massive post-operative systemic-inflammatory-response (SIRS). It is often challenging to differentiate SIRS that are solely surgery-associated from those of post-operative infections. White-Cell-Counts (WCC) and C-Reactive-Protein (CRP) are routinely used as markers for infection, but are non-specific and their elevation is often delayed in PM cases. Other markers need to be evaluated to assist early identification/prediction of post-operative infections.

METHODOLOGY

Prospective evaluation of serum procalcitonin (PCT), CRP and WCC in 50 patients pre-operatively (Day0), and on post-operative days (POD) 1, 3 & 6, following cytoreductive-surgery with or without splenectomy.

RESULTS

Day0 PCT, CRP and WCC values were within normal limits, but increasing physiologically in post-operative period without infection, with noticeable higher PCT in splenectomized patients. In our cohort post-operative infections were diagnosed in 14 patients, often within 48 h. There was a trend for faster rise in serum PCT on POD1 compared to CRP and WCC, and faster PCT decline following appropriate therapy on POD3 and POD6 when infected cases were clinically resolving while WCC and CRP continued to rise, particularly in non-spelenectomised patients. The AUC on POD1 was significantly higher for PCT (0.689) vs. WCC (0.476) and CRP (0.477) (p = 0.04). Sensitivity, specificity, positive-predictive-value and negative-predictive-values for PCT ranged between (57%-100%), (22%-74%), (33%-47%) & (81%-100%), for CRP (28%-78%), (5.5%-86%), (18%-44.4%) & (40%-75.5%) and for WCC (14%-26.5%), (65.5-80.5%), (22%-25%), (67%-70%) respectively.

CONCLUSION

PCT, like WCC and CRP, needs to be interpreted with extreme cautions in the context of infections post-cytoreductive-surgery and should only be used in association with other clinical and investigational findings.

Pathophysiology and burden of infection in patients with diabetes mellitus and peripheral vascular disease: focus on skin and soft-tissue infections

Diabetes mellitus affects 284 million adults worldwide and is increasing in prevalence. Accelerated atherosclerosis in patients with diabetes mellitus contributes an increased risk of developing cardiovascular diseases including peripheral vascular disease (PVD). Immune dysfunction, diabetic neuropathy and poor circulation in patients with diabetes mellitus, especially those with PVD, place these patients at high risk for many types of typical and atypical infections. Complicated skin and soft-tissue infections (cSSTIs) are of particular concern because skin breakdown in patients with advanced diabetes mellitus and PVD provides a portal of entry for bacteria. Patients with diabetes mellitus are more likely to be hospitalized with cSSTIs and to experience related complications than patients without diabetes mellitus. Patients with PVD requiring lower extremity bypass are also at high risk of surgical site and graft infections. Methicillin-resistant Staphylococcus aureus (MRSA) is a frequent causative pathogen in cSSTIs, and may be a significant contributor to surgical site infections, especially in patients who are colonized with MRSA on hospital admission. Patients with cSSTIs and diabetes mellitus or PVD experience lower clinical success rates than patients without these comorbidities, and may also have a longer length of hospital stay and higher risk of adverse drug events. Clinicians should be vigilant in recognizing the potential for infection with multi-drug-resistant organisms, especially MRSA, in these populations and initiating therapy with appropriate antibiotics.

Fusobacterium species infections: clinical spectrum and outcomes at a district general hospital

PURPOSE

Fusobacterium species infections are rare. Recently, however, this potentially deadly pathogen has been attracting interest, and efforts are being made to characterise its epidemiology and clinical spectrum of disease. The aim of our study is to provide further evidence towards this cause, in what is, to date, the largest study of its kind from the UK.

METHOD

A 22-year, retrospective, descriptive study was performed at Royal Hampshire County Hospital. An electronic database was used to identify patients with microbiologically confirmed infection with Fusobacterium, and clinical records were examined to provide further information on the presentation, source, treatment and outcome.

RESULTS

Fusobacterium species infections were identified in 18 patients during the study period, which is an incidence of 0.76 cases/100,000/year. The overall death rate was 29 %. Half of these patients had Fusobacterium necrophorum infections and were a predominantly young, fit and uniquely male population who had excellent outcomes. Among the remaining patients with Fusobacterium species infections, 22 % had infection with F. varium and 11 % with F. nucleatum. These patients were an older cohort who tended to have co-morbidities and unsurprisingly worse outcomes. We identified a number of Fusobacterium bacteraemias likely to have resulted from pressure ulcers, a presentation that has been rarely reported. Interestingly, we also identified a case of neonatal F. nucleatum bacteraemia that was not associated with premature nor stillborn birth.

CONCLUSION

As work continues to depict the spectrum of disease caused by this enigmatic bacterium, it is hoped that improved clinical suspicion will result in better outcomes and management.

Measuring synovial fluid procalcitonin levels in distinguishing cases of septic arthritis, including prosthetic joints, from other causes of arthritis and aseptic loosening

OBJECTIVES

Differentiating septic arthritis from non-septic arthritis can be challenging as the clinical pictures are similar and an efficacious diagnostic test is not yet available. Our objectives in this study were to establish if procalcitonin (PCT) could be reproducibly measured from synovial fluid, if there is a difference in synovial procalcitonin values between patients with septic and non-septic arthritis, respectively, including those with implants and to determine cut-off levels that could be used as a practical tool in the management of these conditions.

METHODS

Using a standard serum assay, synovial fluid PCT levels were measured retrospectively in 26 septic and 50 non-septic predefined arthritis cases. The reproducibility of synovial PCT was also assessed at various concentrations.

RESULTS

Synovial PCT can be measured and is reproducible. In this cohort, statistically significant higher synovial PCT levels were found in cases of septic arthritis than in non-septic arthritis. Sensitivities, specificities and positive and negative predictive values varied at different cut-off levels.

CONCLUSION

The test could be added to other microbiological and biochemical tests and may be used to supplement other clinical, radiological and laboratory findings in the assessment of patients with acute painful joints. In our cohort, findings of very high synovial PCT levels supported an infection process, including in prosthesis-related infections. The high negative predictive value of low synovial PCT levels could exclude infection in both native and prosthetic joints. Larger prospective studies are needed to further validate these results and to examine the cost effectiveness of synovial PCT.

Efficacy and safety of IV/PO moxifloxacin and IV piperacillin/tazobactam followed by PO amoxicillin/clavulanic acid in the treatment of diabetic foot infections: results of the RELIEF study

OBJECTIVE

The aim was to compare the efficacy and safety of two antibiotic regimens in patients with diabetic foot infections (DFIs).

METHODS

Data of a subset of patients enrolled in the RELIEF trial with DFIs requiring surgery and antibiotics were evaluated retrospectively. DFI was diagnosed on the basis of the modified Wagner, University of Texas, and PEDIS classification systems. Patients were randomized to receive either intravenous/oral moxifloxacin (MXF, N = 110) 400 mg q.d. or intravenous piperacillin/tazobactam 4.0/0.5 g t.d.s. followed by oral amoxicillin/clavulanate 875/125 mg b.d. (PIP/TAZ-AMC, N = 96), for 7-21 days until the end of treatment (EOT). The primary endpoint was clinical cure rates in the per-protocol (PP) population at the test-of-cure visit (TOC, 14-28 days after EOT).

RESULTS

There were no significant differences between the demographic characteristics of PP patients in either treatment group. At TOC, MXF and PIP/TAZ-AMC had similar efficacy in both the PP and intent-to-treat (ITT) populations: MXF: 76.4 % versus PIP/TAZ-AMC: 78.1 %; 95 % confidence interval (CI) -14.5 %, 9.0 % in the PP population; MXF: 69.9 % versus PIP/TAZ-AMC: 69.1 %; 95 % CI -12.4 %, 12.1 % in the ITT population. The overall bacteriological success rates were similar in both treatment groups (MXF: 71.7 % versus PIP/TAZ-AMC: 71.8 %; 95 % CI -16.9 %, 10.7 %). A similar proportion of patients (ITT population) experienced any adverse events in both treatment groups (MXF: 30.9 % versus PIP/TAZ-AMC: 31.8 %, respectively). Death occurred in three MXF-treated patients and one PIP/TAZ-AMC-treated patient; these were unrelated to the study drugs.

CONCLUSION

Moxifloxacin has shown favorable safety and efficacy profiles in DFI patients and could be an alternative antibiotic therapy in the management of DFI.

CLINICAL TRIAL

NCT00402727.

Diagnosis and management of skin and soft-tissue infections (SSTI): a literature review and consensus statement on behalf of the Italian Society of Infectious Diseases and International Society of Chemotherapy

Skin and soft-tissue infections (SSTIs) are among the most common bacterial infections, posing considerable diagnostic and therapeutic challenges and resulting in significant morbidity and mortality among patients as well as increased healthcare costs. eight members of the SSTI working group of the Italian Society of infectious Diseases prepared a draft of the statements, grading the quality of each piece of evidence after a careful review of the current literature using MEDLINE database and their own clinical experience. Statements were graded for their strength and quality using a system based on the one adopted by the Infectious Diseases Society of America (IDSA). The manuscript was successively reviewed by seven members of the SSTI working group of the international Society of Chemotherapy, and ultimately re-formulated by all e xperts. the microbiological and clinical aspects together with diagnostic features were considered for uncomplicated and complicated SSTIs. Antimicrobial therapy was considered as well -both empirical and targeted to methicillin-resistant Staphylococcus aureus (MRSA) and/or other main pathogens.

Antimicrobial treatment of "complicated" intra-abdominal infections and the new IDSA guidelines ? a commentary and an alternative European approach according to clinical definitions

Recently, an update of the IDSA guidelines for the treatment of complicated intraabdominal infections has been published. No guideline can cater for all variations in ecology, antimicrobial resistance patterns, patient characteristics and presentation, health care and reimbursement systems in many different countries. In the short time the IDSA guidelines have been available, a number of practical clinical issues have been raised by physicians regarding interpretation of the guidelines. The main debatable issues of the new IDSA guidelines are described as follows: The authors of the IDSA guidelines present recommendations for the following subgroups of "complicated" IAI: community-acquired intra-abdominal infections of mild-to-moderate and high severity and health care-associated intra-abdominal infections (no general treatment recommendations, only information about antimicrobial therapy of specific resistant bacterial isolates). From a clinical point of view, "complicated" IAI are better differentiated into primary, secondary (community-acquired and postoperative) and tertiary peritonitis. Those are the clinical presentations of IAI as seen in the emergency room, the general ward and on ICU. Future antibiotic treatment studies of IAI would be more clinically relevant if they included patients in studies for the efficacy and safety of antibiotics for the treatment of the above mentioned forms of IAI, rather than conducting studies based on the vague term "complicated" intra-abdominal infections. - The new IDSA guidelines for the treatment of resistant bacteria fail to mention many of new available drugs, although clinical data for the treatment of "complicated IAI" with new substances exist. Furthermore, treatment recommendations for cIAI caused by VRE are not included. This group of diseases comprises enough patients (i.e. the entire group of postoperative and tertiary peritonitis, recurrent interventions in bile duct surgery or necrotizing pancreatitis) to provide specific recommendations for such antimicrobial treatment. - A panel of European colleagues from surgery, intensive care, clinical microbiology and infectious diseases has developed recommendations based on the above mentioned clinical entities with the aim of providing clear therapeutic recommendations for specific clinical diagnoses. An individual patient-centered approach for this very important group of diseases with a substantial morbidity and mortality is essential for optimal antimicrobial treatment.

Treatment of complicated skin and soft-tissue infections caused by resistant bacteria: value of linezolid, tigecycline, daptomycin and vancomycin

Antibiotic-resistant organisms causing both hospital- and community-acquired complicated skin and soft-tissue infections (cSSTI) are increasingly reported. A substantial medical and economical burden associated with MRSA colonisation or infection has been documented. The number of currently available appropriate antimicrobial agents is limited. Good quality randomised, controlled clinical trial data on antibiotic efficacy and safety is available for cSSTI caused by MRSA. Linezolid, tigecycline, daptomycin and vancomycin showed efficacy and safety in MRSA-caused cSSTI. None of these drugs showed significant superiority in terms of clinical cure and eradication rates.To date, linezolid offers by far the greatest number of patients included in controlled trials with a strong tendency of superiority over vancomycin in terms of eradication and clinical success.. - Tigecycline is an alternative in polymicrobial infections except by diabetic foot infections. Daptomycin might be a treatment option for cases of cSSTI with MRSA bacteremia. cSSTI caused by resistant Gram-negative bacteria are a matter of great concern. The development of new antibiotics in this area is an urgent priority to avoid the risk of a postantibiotic era with no antimicrobial treatment options. An individual approach for every single patient is mandatory to evaluate the optimal antimicrobial treatment regimen.

A European survey of antibiotic management of methicillin-resistant Staphylococcus aureus infection: current clinical opinion and practice

Although the epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) varies across Europe, healthcare-associated MRSA infections are common in many countries. Despite several national guidelines, the approach to treatment of MRSA infections varies across the continent, and there are multiple areas of management uncertainty for which there is little clinical evidence to guide practice. A faculty, convened to explore some of these areas, devised a survey that was used to compare the perspectives of infection specialists from across Europe on the management of MRSA infections with those of the faculty specialists. The survey instrument, a web-based questionnaire, was sent to 3840 registered delegates of the 19th European Congress of Clinical Microbiology and Infectious Diseases, held in April 2009. Of the 501 (13%) respondents to the survey, 84% were infection/microbiology specialists and 80% were from Europe. This article reports the survey results from European respondents, and shows a broad range of opinion and practice on a variety of issues pertaining to the management of minor and serious MRSA infections, such as pneumonia, bacteraemia, and skin and soft tissue infections. The issues include changing epidemiology, when and when not to treat, choice of treatment, and duration and route of treatment. The survey identified areas where practice can be improved and where further research is needed, and also identified areas of pan-European consensus of opinion that could be applied to European guidelines for the management of MRSA infection.

Universal maternal screening for neonatal group B streptococcal disease

Group B streptococcal infection is a leading cause of neonatal morbidity and mortality in the developed world. Data obtained in our region suggest that the incidence in the UK may be higher than previously reported, and together with the results of a pilot study indicate that preventive strategies based on maternal risk factors alone would prevent less than half the cases of neonatal disease.

Salmonella osteoarticular infection without predisposing factors

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Subcutaneous nodules with pseudomonas septicaemia in an immunocompetent patient

Pseudomonas septicaemia presenting with subcutaneous nodules, though rare, is well described in immunocompromized populations. It is, however, very uncommon in immunocompetent patients. We describe a case of a 42-year-old woman who presented with community-acquired. Pseudomonas aeruginosa septicaemia and subcutaneous nodules. No precipitating cause or immune dysfunction was found. She was successfully treated with appropriate antibiotics, respiratory and cardiovascular support in the Intensive Care Unit. The difficulty in eradicating the organism from the skin lesion and the need for investigating the immune function of septicaemia patients are discussed.

Cerebrospinal nematodiasis in a white-handed gibbon (Hylobates lar) due to Baylisascaris sp

An adult white-handed gibbon (Hylobates lar) at a zoo in eastern Kansas was euthanized after developing a head tremor, generalized motor incoordination, and partial paresis of the right arm that persisted over 2 yr. Magnetic resonance imaging early in the course of the disease demonstrated a localized left frontal lobe cerebritis. Larvae morphologically consistent with a Baylisascaris species were seen in tissue sections of the cerebrum and cerebellum. Epizootiologic investigation, which included qualitative fecal flotations, evaluation of soil samples for nematode eggs, and necropsy examination of livetrapped raccoons (Procyon lotor), indicated that Baylisascaris procyonis was most likely to have caused the cerebrospinal nematodiasis in this gibbon.

Spinal abscess of Haemophilus paraphrophilus. A case report

STUDY DESIGN

A case of paraspinal abscess formation from Haemophilus paraphrophilus is presented.

OBJECTIVES

To describe a case of paraspinal abscess formation from H. paraphrophilus, a fastidious commensal organism of the mouth and pharynx. A precise bacteriologic identification can be difficult; techniques for such identification are discussed.

SUMMARY OF BACKGROUND DATA

Spinal abscess caused by H. paraphrophilus is unusual and can be very difficult to diagnose.

METHODS

The etiology, clinical presentation, technical examinations, and treatment are reviewed.

RESULTS

Prolonged antibiotic treatment was curative, although surgery was considered.

CONCLUSIONS

Bacteriologic diagnoses in these rare infections are difficult. Antibiotic therapy was curative in the patient described.

Outbreak of cryptosporidiosis associated with a swimming pool in Andover

An outbreak of eight cases of cryptosporidiosis in Hampshire over a period of eight weeks in the summer of 1996 was linked to use of one swimming pool. Cryptosporidial oocysts were not isolated from samples of backwash, but the presence of enterobius ova indicated faecal contamination and a case control study including the first four primary cases suggested an association with immersion in the pool. Even in small outbreaks case control studies can provide useful supportive evidence as to the possible source of infection.

Prevalence of Bartonella henselae antibodies in pet cats throughout regions of North America

Cat exposure has been directly associated with the development of human Bartonella henselae infections, resulting in cat-scratch disease, bacillary angiomatosis, or bacteremia. The prevalence of serum antibody titers to B. henselae was determined for selected pet cats from 33 geographic locations throughout the United States and several areas in western Canada. Seroprevalences paralleled increasing climatic warmth (P < .02) and annual precipitation (P < .03). These warm, humid areas with the highest seroprevalence would also have the highest number of potential arthropod vectors. The southeastern United States, Hawaii, coastal California, the Pacific Northwest, and the south central plains had the highest average prevalences (54.6%, 47.4%, 40.0%, 34.3%, and 36.7%, respectively). Alaska, the Rocky Mountain-Great Plains region, and the Midwest had low average prevalences (5.0%, 3.7%, and 6.7%, respectively). Overall, 27.9% (175/628) of the cats tested were seropositive. The seroprevalence of B. henselae in cats varies throughout the United States and appears to be influenced by climate.

Clinic referral for oppositional defiant disorder: relative significance of attachment and behavioral variables

Attachment classifications have been found to distinguish clinic-referred, oppositional preschool boys from controls, but there has been no previous effort to examine the relative contribution of attachment when behaviors from a social learning perspective are also considered. The present study examined the contribution of attachment and behavioral variables to the prediction of clinic referral for oppositional defiant disorder in a sample of preschool boys. We hypothesized that the attachment measures would offer better discrimination of clinic and control group boys at this age. This hypothesis was confirmed when the attachment measures were compared with the parent-child behaviors most strongly associated with social learning conceptualizations of disruptive problems (maternal commands and criticism, and child noncompliance), but rejected in a more stringent test in which the attachment measures were compared with the behavioral variables distinguishing the groups in this particular sample.

Infection of vascular prostheses

Graft infection occurred in 11 of 322 patients (3.4%) who had insertion of a vascular prosthesis for peripheral vascular disease during a 4-year period. The groin was the most common site of infection and multiple resistant Staphylococcus aureus (MRSA) was the most common organism responsible. Six of 7 MRSA infections occurred following a procedure involving a previously placed graft and/or a groin incision. Prophylactic antibiotics effective against MRSA are recommended for patients having a revisional procedure, especially involving the groin.

Establishment of a vascular graft infection model in the sheep carotid artery

A study was performed to assess whether a model of vascular graft infection could be established in sheep carotid artery. Either a protein sealed Dacron or a polytetrafluoroethylene (PTFE) graft was used in 22 sheep while a control operation was performed on 4 animals. Staphylococcus aureus in concentrations of 10(2), 10(4), 10(6) or 10(8) colony-forming units (CFU) was inoculated into the wound before closure. No infection occurred with an inoculum of 10(2). The lowest concentration of organism producing infection was 10(4) for PTFE, 10(6) for Dacron and 10(8) for controls. Six of eleven Dacron grafts and seven of ten PTFE grafts became infected. The sheep carotid artery has proven a satisfactory model for studies of vascular graft infection.

Antibiotic resistance in enterococci at a teaching hospital

Antibiotic resistance in enterococci is becoming increasingly common throughout the world. Of particular therapeutic concern are strains which produce beta-lactamase, display high-level aminoglycoside resistance or show plasmid-mediated resistance to vancomycin. A prospective survey of 112 enterococcal isolates has been carried out to determine the extent of these resistance mechanisms in a Sydney teaching hospital. No beta-lactamase production was found. Eleven (9.8%) strains displayed high-level streptomycin resistance (MIC greater than 2048 mg/l), and 2 (1.8%) strains high-level gentamicin resistance (MIC greater than 2048 mg/l). No vancomycin resistance was observed. Enterococcal resistance is not as common at this hospital as in many centres in other countries. High-level aminoglycoside resistance may be missed on routine sensitivity testing. All enterococcal isolates from patients with serious infections should be screened for high-level aminoglycoside resistance.

Aeromonas septicemia: relationship of species and clinical features

Thirteen patients with Aeromonas species septicemia were seen at Westmead Hospital between 1983 and 1987. In 10 patients (77%) septicemia was caused by A. sobria, and in 3 (23%) by A. hydrophila, A. caviae was not isolated. Chronic underlying illness was present in 10 patients (77%), hematological malignancy being the most common (46%). The average age of the patients was 65.8 years. Seven patients (54%) presented with clinical sepsis, diarrhea and abdominal pain. The biliary tract, lung and soft tissue were other primary sites of infection. Nosocomial infection occurred in 5 patients (38%). Cross-infection was not seen. Contact with fresh water or fish was observed in only 2 patients (15%). The majority of cases occurred in the warmer months of the year. The overall mortality was 46%. All isolates of Aeromonas species were resistant to ampicillin 8 mg/L. Ten isolates were resistant to tobramycin 1 mg/L, and 3 to tobramycin 4 mg/L. In contrast, 3 isolates were resistant to gentamicin 1 mg/L, and none to 4 mg/L. The isolates showed a varied pattern of resistance to other antibiotics tested, but all were susceptible to piperacillin 64 mg/L, imipenem 4 mg/L, ciprofloxacin 1 mg/L, and amikacin 16 mg/L.

My student elective. Along the White Nile

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