Massive Scrotal Hematoma due to Ruptured Anastomotic Pseudoaneurysm in a Patient with Aortobifemoral Bypass Surgery: CTA Evaluation

A 74-year-old male patient was presented with scrotal swelling and a pulsatile mass of the left femoro-inguinal region. His medical history included hypertension, coronary artery disease, respiratory failure, and an aortobifemoral bypass surgery performed 7 years ago. Ultrasound evaluation revealed a massive scrotal hematoma. Computed tomography angiography (CTA) was conducted, confirming the aortobifemoral graft existence and revealing bilateral anastomotic pseudoaneurysms with the left one being ruptured, resulting in extension of the hematoma to the left femoro-inguinal region and the scrotum. An emergency surgery was performed, where proximal control of the left limb of the synthetic graft as well as distal control of the iliac vessels were accomplished. After the control of the hemorrhage, an iliofemoral bypass with a Polytetrafluoroethylene (PTFE) 6 mm synthetic graft was placed. Unfortunately, the patient passed away during the first postoperative day due to myocardial infarction.

A diversity of Antibiotic-resistant Staphylococcus spp. in a Public Transportation System

OBJECTIVES

Our goal was to determine the diversity and abundance of Staphylococcus bacteria on different components of a public transportation system in a mid-sized US city (Portland, Oregon) and to examine the level of drug resistance in these bacteria.

METHODS

We collected 70 samples from 2 cm × 4 cm sections from seven different areas on buses and trains in Portland, USA, taking 10 samples from each area. We isolated a subset of 14 suspected Staphylococcus spp. colonies based on phenotype, and constructed a phylogeny from16S rRNA sequences to assist in identification. We used the Kirbye-Bauer disk diffusion method to determine resistance levels to six common antibiotics.

RESULTS

We found a range of pathogenic Staphylococcus species. The mean bacterial colony counts were 97.1 on bus and train floors, 80.1 in cloth seats, 9.5 on handrails, 8.6 on seats and armrests at bus stops, 3.8 on the underside of seats, 2.2 on windows, and 1.8 on vinyl seats per 8 cm(2) sample area. These differences were significant (p < 0.001). Of the 14 isolates sequenced, 11 were staphylococci, and of these, five were resistant to penicillin and ampicillin, while only two displayed intermediate resistance to bacitracin. All 11 isolates were sensitive to trimethoprim-sulfamethoxazole, vancomycin, and tetracycline.

CONCLUSIONS

We found six different strains of Staphylococcus, and while there were varying levels of drug resistance, we did not find extensive levels of multidrug-resistant bacteria, and no S. aureus was found. We found floors and cloth seats to be areas on buses and trains that showed particularly high levels of bacteria.

Surgical site and vascular infections: treatment and prophylaxis

Vascular infections typically include those of surgical sites, prosthetic grafts, and vascular ulcers, including some diabetic foot ulcers. Each of these infections represents a serious health concern, particularly among individuals with comorbid conditions who are at an increased risk of morbidity and mortality. Surgical site infections occur primarily as a result of contamination by skin organisms during surgery, whereas prosthetic graft infections result typically from a progressive wound infection. Diabetic foot ulcers and infections are especially complicated and difficult to treat. They occur in individuals with systemic illness that has compromising effects on the nervous, vascular, musculoskeletal, and immunologic systems. Vascular infections, like those elsewhere in the body, reflect an imbalance between the host and bacteria. Efforts to limit or prevent the likelihood of patients developing these infections centre on reducing the bacterial inoculum by means of asepsis and antisepsis. As well as size of the bacterial inoculum, the bacterial properties of pathogenicity and resulting virulence are also significant. The most frequent pathogenic bacteria encountered in surgical patients are Gram-positive cocci (e.g. Staphylococcus aureus and streptococci). Strains with multiple antibiotic resistance (e.g. meticillin resistant S. aureus [MRSA], S. epidermidis, and vancomycin-resistant enterococci [VRE]) can cause significant surgical site infection problems. Local resistance patterns and surveillance efforts are essential to ensure appropriate empiric antibiotic selection for prophylaxis or treatment.

Antimicrobial chemotherapy in the control of surgical infectious complications

In spite of the progress in surgical technique and antibiotic prophylaxis, postoperative infection still accounts for both the commonest surgical complication and one of the most frequent nosocomial infections, also causing an increase in duration and costs of hospital stay. The choice of treatment for post-surgical infections requires an understanding of the usual infecting flora, available antimicrobial agents, and susceptibility patterns. The most common organisms in simple wound infection are gram-positive cocci and mainly Staphylococcus aureus. Staphylococcus epidermidis and S. aureus (quite often methicillin-resistant strains) are the organisms which predominate in the infectious complications following clean surgical procedures with implantation of vascular grafts or prosthetic devices. Mixed aerobic and anaerobic flora are mainly responsible for cases of intra-abdominal and intra-pelvic postoperative infections: the most common aerobes are Enterobacteriaceae (Escherichia coli, Proteus spp., and others) and enterococci, and among anaerobes Bacteroides fragilis group prevails. Adequate drainage and surgical control of the source of infection, when needed, and adjunctive effective antimicrobial therapy are important factors in successful treatment of postoperative infections. Semisynthetic penicillinase-resistant penicillins and glycopeptides (vancomycin and teicoplanin) are the drugs of choice for the treatment of infections caused by penicillin-resistant methicillin-sensitive, and methicillin-resistant, respectively, S. aureus and S. epidermidis. For the treatment of intra-abdominal and intra-pelvic infections, animal and human studies support the recommendation that treatment should be directed against both gram-negative enteric and anaerobic bacteria. Combinations of aminoglycosides with clindamycin or metronidazole have been widely used with great success; however adverse reactions such as nephrotoxicity and ototoxicity have been a problem in some patients. In recent years monotherapy with either a carbapenem (imipenem/cilastatin or meropenem) or a penicillin/beta-lactamase inhibitor combination has been proposed. Among these combination antimicrobials, piperacillin combined with tazobactam is a very well designed formulation. Indeed, piperacillin is active against a broad range of gram-negative and gram-positive pathogens, and tazobactam is a potent beta-lactamase inhibitor which acts on a variety of clinically important plasmid and chromosomal beta-lactamases. This combination seems particularly attractive for the treatment of mixed polymicrobial anaerobic-aerobic infections such as intra-abdominal and intra-pelvic postoperative infections.

Ruthenium red and the bacterial glycocalyx

Ruthenium red, a promising cationic reagent for electron microscopy (EM), has long been an important tool in histology. The reagent was initially used by botanists as a semispecific stain for pectic substances, but it has gradually been embraced by investigators in microbiology and the animal sciences as a stain for anionic glycosylated polymeric substances. Luft developed a reliable method and demonstrated that ruthenium red was a useful reagent for visualizing ultrastructural detail. Many investigators, using modifications of Luft's approach, have identified numerous applications for this important reagent. Ruthenium red has been used to show the ultrastructural detail of bacterial glycocalyces. Strong, sharp and consistent observations of this ultrastructural component of the bacterial cell have given a better understanding its fibrous anionic matrix. Any variations in staining owing to artifactual alteration of the fine delicate ultrastructural features have been overcome by incorporation of diamine lysine into ruthenium red methods, thus providing flexible processing times under less than ideal laboratory sampling conditions. Ruthenium red has broad utility in the biological sciences, and in combination with lysine, it is an excellent EM stain for enhanced visualization of bacterial glycocalyx from culture or from clinical specimens.

Dental infection in vascular surgical patients

Seventy patients, 18 women and 52 men of mean age 68 (range 52-81) years, with vascular disease were studied using the Community Periodontal Index of Treatment Needs (CPITN). Twenty-six were edentulous and 44 dentate; 32 dentate patients were wearing partial dentures. All had occlusive peripheral arterial disease (ankle:brachial pressure index less than 0.9) or aortic aneurysm. No significant periodontal pathology was found in edentulous patients. Of the dentate patients, 28 were in the significant pathology range (CPITN 4) and 12 were in the moderate pathology group (CPITN 3); only four had no significant pathology (CPITN 0-2). As a proportion of prosthetic vascular graft infections may be due to dental sepsis, surgeons should consider referral for dental assessment before elective bypass grafting and patients should be warned about the importance of dental care after operation.

Surgical wound infection

Wound infections remain a major source of postoperative morbidity, accounting for about a quarter of the total number of nosocomial infections. Today, many of these infections are first recognized in the outpatient clinic or in the patient's home due to the large number of operations done in the outpatient setting. This leads to errors in establishing the true incidence of their occurrence but undoubtedly decreases the overall real cost and length of hospital stay. The pathogens implicated in the development of wound infections remain largely the human microorganisms from the exogenous environment and the endogenous organ microflora. Many perioperative factors have been identified that increase the incidence of the development of postoperative wound infection. Avoidance of these factors as well as the appropriate use of perioperative antibiotic prophylaxis has decreased the incidence of wound infection. During the last decade many studies have reported on the individual risk factors that favor the development of postoperative infectious complications in various surgical procedures. It is hoped that this knowledge may allow for prospective alterations in the preventative and therapeutic modalities in the high-risk patient in the studies designed in the 1990s. The use of effective infection surveillance both in the hospital and in the outpatient setting is mandatory in order to collect meaningful data. The use of computer technology will greatly facilitate the proper surveillance, analysis, and control of infections in the surgical patient.

Sequential analysis of staphylococcal colonization of body surfaces of patients undergoing vascular surgery

Slime-producing coagulase-negative staphylococci are pathogens in vascular surgery by virtue of their ability to adhere to and persist on prosthetic graft material. Inguinal and abdominal skin sites were cultured in 41 patients upon hospitalization, and slime production and antimicrobial susceptibility were assessed in all recovered staphylococcal isolates. Twenty-one patients eventually underwent lower-extremity revascularization. In the operative population, cultures were also obtained on the day of surgery and fifth postoperative day. All 21 patients received perioperative cefazolin. Of 327 coagulase-negative staphylococci recovered, Staphylococcus epidermidis (47%), S. haemolyticus (21%), and S. hominis (10%) were the predominant isolates. Slime-producing coagulase-negative staphylococci were recovered from 17 of 21 patients at admission but only from 8 of 21 patients on day 5 postoperation (P less than 0.05). S. epidermidis isolates demonstrated increasing multiple resistance from admission to 5 days postoperation to methicillin, gentamicin, clindamycin, erythromycin, and trimethoprim-sulfamethoxazole (P less than 0.05). All coagulase-negative staphylococcal isolates were susceptible to ciprofloxacin and vancomycin. Slime-producing capability was not associated with increased methicillin resistance for the recovered isolates. The data demonstrate that patients enter the hospital colonized with slime-producing strains of coagulase-negative staphylococci and that during hospitalization the staphylococcal skin burden shifts from a predominately susceptible to a resistant microbial population, which may enhance the importance of slime production as a risk factor in lower-extremity revascularization.