A.M. Yinnon

Susceptibility trends in bacteraemias: analyses of 7544 patient-unique bacteraemic episodes spanning 11 years (1990-2000).

The aim of the present study was to design more accurate tools for the selection of appropriate antimicrobial therapy for hospitalized patients with suspected sepsis. We created a large database comprising data on all patient-unique blood cultures obtained over an 11 year period (1 January, 1990 through 31 December, 2000). Improved statistical tools were applied to assess the trends in in vitro activity of individual antibiotic agents against various bacteria over time, and to calculate susceptibility rates of subsets of organisms. During the 11 year study period, 173571 blood cultures were obtained, of which 17703 (10.2%) were positive, with 7544 patient-unique blood cultures (4.3%). The mean annual number of positive, patient-unique cultures was 686 (standard deviation=79). The 10 most frequently isolated organisms were: Escherichia coli (1494), Staphylococcus aureus (1240), Klebsiella pneumoniae (779), Enterococcus spp. (631), Pseudomonas aeruginosa (488), Streptococcus pneumoniae (447), Enterobacter spp. (338), Acinetobacter spp. (298), Proteus mirabilis (260) and Candida spp. (254). No significant change was detected in the annual rates (means, standard deviations) per 1000 admissions of these organisms: the highest was E. coli (5.5, 1), the lowest was Candida (1, 0.3). Forty percent of organisms (N=2943) were obtained from patients in the emergency department (ED), 23% (1744) in medical departments, 15% (1134) in paediatric units, 13% (998) on surgical wards and 9% (709) in intensive care units (ICUs). Trend statistical analysis revealed a significant decrease in susceptibility in ED Enterobacteriaceae to eight of 15 (53%) tested antimicrobials, with a mean annual decrease of 1.6%+/-0.6%, in the ICU isolates, a significant decrease was detected in only five (33%) of the tested antimicrobials, with a mean annual decrease of 2.5%+/-1.3%. The difference in susceptibility between ED and ICU isolates was significant for all antimicrobials (P<0.001). A significant decrease in the susceptibility of E coli to nine of 15 drugs (60%) was detected, ranging from 0.7% to 2.7% annually. In K. pneumoniae a significant decrease in susceptibility of K. pneumoniae was detected with only two agents. Pseudomonas spp. isolates remained highly sensitive to all traditional anti-pseudomonal agents, without significant decay in sensitivity rates over time. Susceptibility of S. aureus to methicillin decreased significantly for several subsets of patients (P<0.001). Marked differences in susceptibility rates between the departments were detected. Trend statistical analyses, when appropriately applied to multi-year databases of microbial susceptibilities, may yield susceptibility tables that are significantly more accurate than traditional semi-annual or annual tables.

Clinical characteristics of patients with psoas abscess due to non-typhi Salmonella

Infections due to Salmonella spp. are common and their incidence appears to be increasing in many countries [1, 2]. Non-typhoidal Salmonella infections are usually associated with contaminated food products [3]. Salmonellosis may present in five forms: asymptomatic chronic carrier state, gastroenteritis, enteric fever, bacteremia and extraintestinal localized complications, of which endovascular infection is one of the most serious [4, 5, 6]. Psoas abscess has been reported only very rarely. Between 1990 and 2000, 7,544 patients were diagnosed in our hospital with bacteremia. Of these patients, 120 (1.6%) had Salmonella bacteremia [7]. Eight of these patients (7%) had Salmonella typhi, and of the 112 patients with non-typhi Salmonella bacteremia, 68 (61%) were children and 44 (39%) were adults. None of the children nor any of the eight adults younger than 50 years old were diagnosed with psoas abscess. However, of the 36 adults older than 50 years who had non-typhi Salmonella bacteremia, two patients (5.5%) had a psoas abscess. It is not unlikely that bacteremia in these patients was secondary to the psoas abscess, which may have formed weeks or months earlier after primary bacteremia or direct extension from an adjacent site. The association of Salmonella bacteremia and localized symptoms led to the conduction of appropriate tests and the eventual diagnosis of psoas abscess. Patient No. 1, a 75-year-old woman with an 18-month history of idiopathic thrombocytopenic purpura (ITP) was seen in March 2000 for relapse of ITP. She had been previously treated with steroids, which were tapered and discontinued 3 months earlier. Treatment with steroids was resumed and intravenous gammaglobulin was added. Several days later she complained of a sudden onset of severe pain in her left hip, accompanied by a low-grade fever (37.5–37.8 C). A bone scan was suggestive of avascular necrosis of the neck of the left femur. A radiogram of the joint was negative. Two blood cultures and a urine culture grew Salmonella enteritidis. She was started on ampicillin 8 g/day in four divided doses. A computerized tomographic (CT) scan of the abdomen revealed multiple abscesses in the left iliopsoas muscle. Oral ciprofloxacin, 750 mg twice daily, was added. A drain was inserted into the left iliac fossa and pus was drained, from which Salmonella enteritidis was isolated. After prolonged percutaneous drainage and antibiotic treatment, cultures of the drained material became negative, and the patient made a complete recovery. Patient No. 2, a 74-year-old woman, was admitted to hospital in May 2000 with a 2-month history of rightsided groin pain radiating to the right hip and upper thigh without trauma, and a temperature of 38.8 C that had started the day before. An orthopedic surgeon had examined her a month previously and had ascribed her symptoms to discopathy. A bone scan, performed 1 month prior to her admission, was reported as demonstrating an increased uptake in the spine and right hip joint, which was ascribed to arthritic changes. Her past medical history included myasthenia gravis for which she had undergone Y. Schlesinger · A. M. Yinnon ()) · D. Raveh Infectious Disease Unit, Shaare Zedek Medical Center, P.O. Box 3235, 91031 Jerusalem, Israel e-mail: Yinnon@SZMC.org.il Tel.: +972-2-6555076 Fax: +972-2-6555076

Direct fluconazole susceptibility testing of positive Candida blood cultures by flow cytometry.

The standard methods for yeast susceptibility testing require 24–48 h of incubation. As there has been an increase in incidence of non‐albicans Candida species, the clinician is very often wary of initiating therapy with fluconazole until a final susceptibility report is generated, especially when treating very sick patients. A rapid reliable susceptibility testing method would enable the clinician to prescribe fluconazole, thus avoiding more toxic or expensive therapy. To determine the feasibility of direct susceptibility testing of Candida species to fluconazole by a rapid flow cytometric method, 50 Candida strains were seeded into blood culture bottles and were tested for susceptibility to fluconazole directly from the bottles after their being flagged as positive by the blood culture instrument. Minimal inhibitory concentration (MIC) determined by fluorescent flow cytometry (FACS) showed excellent agreement to that determined by macrodilution. Following the seeding experiments, 30 true patient specimens were tested directly from positive blood cultures, and MIC determined by both methods showed excellent agreement. Antifungal susceptibility testing by FACS directly from positive blood culture bottles is a reliable, rapid method for susceptibility testing of Candida to fluconazole. The method allows same‐day results, does not require subculture to agar media, and can greatly assist in the selection of appropriate antifungal therapy.

Use of time-trend analysis in the design of empirical antimicrobial treatment of urinary tract infection.

Selection of empirical treatment of hospitalized patients with urinary tract infection (UTI) is usually based on the results of urine culture as obtained from the local microbiology laboratory. In order to improve the precision and reliability of traditional methods, we analyzed temporal changes in the results of urine culture and antibiograms and stratified the results by inpatient department and the presence/absence of an indwelling catheter. The database consisted of urine cultures obtained during the first 3 months of each year over a 10-year period between 1991 and 2000. Only urine samples that grew a single organism at a concentration of >105 cfu were included in the analysis. Trend statistical tools, readily available but thus far not used for microbiological analyses, were applied to assess the decay in activity of individual antibiotic agents over time and to calculate susceptibility rates of organisms in subsets of urine samples. Organisms, antimicrobial susceptibility rates and the degree of decay in antimicrobial susceptibility rates varied significantly according to the location of the patient in the hospital and the presence of an indwelling catheter. Stratified trend analysis is a useful tool that can be helpful in designing and adapting clinical guidelines for the selection of appropriate empirical antibiotic treatment for the individual patient with urinary tract infection.

Q fever endocarditis; not always expected

Q fever endocarditis is a chronic disease with protean manifestations. The clinical and serological manifestations of nine patients diagnosed as having Q fever endocarditis during a 19-year period are reviewed. Four patients (44%) required valve replacement due to congestive heart failure. Three of these four patients were diagnosed as having Q fever endocarditis only after elective valve surgery, by histopathological examination of the valve and subsequent serological tests. Prior to surgery they were afebrile and had no other symptom or sign indicative of endocarditis. The antibiotic treatment and the decreasing titres of Q fever antibodies of all nine patients during several years of follow-up are summarized. Careful assessment of heart valves for histopathological evidence of inflammation is suggested, even after elective replacement. If found, clinical and laboratory evaluation should include determination of anti-Coxiella burnetti antibodies.

Intrauterine device as source of pneumococcal intra-abdominal infection and small-bowel obstruction

Pneumococcal peritonitis in adults is a rare disease, occurring mainly in patients with liver cirrhosis or nephrotic syndrome [1, 2]. Although pneumococcus is not considered part of the normal flora of the female genital tract, it has been a cause of infection in the female genital tract and of peritonitis, especially in young women [2–5]. We report a case of pneumococcal peritonitis presenting as a small-bowel obstruction in a young woman with an intrauterine contraceptive device (IUD). A 38-year-old previously healthy woman was admitted to the emergency room with diffuse abdominal pain, vomiting and diarrhea, which began 3 days prior to admission. On physical examination she had a pulse rate of 130 beats per minute, blood pressure of 120/80 mmHg, and a fever of 37.3°C. Her abdomen was slightly distended and soft with diffuse tenderness, but no peritoneal signs were evident. Laboratory results were normal except for leukocytosis (21×10 l), a creatinine level of 177 μmol/l, and a blood urea nitrogen level of 13.2 mmol/l. The initial diagnosis made in the emergency room was acute gastroenteritis, and the patient was treated with intravenous fluids. Twenty hours later (or 4 days after the onset of symptoms), the diarrhea ceased, but the patient remained toxic, with crampy abdominal pain and vomiting. Her abdomen became much more distended and tender. A gastric catheter was inserted, and a large volume of feculent fluid was drained. A diagnosis of small-bowel obstruction was made based on the findings of an abdominal radiograph and subsequent computed tomography scan of the abdomen. During surgery, some serous fluid in the abdomen and extremely distended loops of small-bowel covered with a thick yellowish exudate were observed. The terminal ileum was fixed in the pouch of Douglas with adhesion to the pelvic peritoneum. Following release and extraction of purulent fluid, a slightly edematous uterus and fallopian tubes were observed along with normal ovaries. After complete extraction of abdominal fluid and free particles of exudate, the laparotomy wound was closed. The IUD was removed immediately after the operation, and abdominal fluid, exudates and the IUD were sent for culture. Intravenous administration of ampicillin, gentamicin and metronidazole, which had been started prior to surgery, was continued. The following day, culture of abdominal fluid, exudates and the IUD all yielded growth of Streptococcus pneumoniae. In view of the severity of the infection and the possibility of polymicrobial infection, treatment was changed to intravenous amoxicillin-clavulanate alone, followed by oral amoxicillin-clavulanate for 1 week. The patient had an uneventful postoperative period and was discharged from the hospital on postoperative day 7. Three months following surgery, she remained well. Peritonitis can be classified as primary or secondary, based upon how the causative organism gained access to the peritoneal cavity; i.e., without loss of bowel wall integrity (primary) or through loss of bowel mucosal wall integrity (secondary) [1]. Primary peritonitis is usually caused by gram-negative bacilli reaching the peritoneal cavity either by a process of translocation from the bowel or, occasionally, by hematogenous spread from a distant infectious site. Secondary peritonitis is usually characterized by polymicrobial infection reflecting the nature of normal intestinal flora. B. Rudensky (*) Department of Clinical Microbiology, Shaare Zedek Medical Center, Faculty of Health Sciences, Ben Gurion University of the Negev, P.O. Box 3235 Jerusalem, 91031, Israel e-mail: rudensky@szmc.org.il Tel.: +972-2-6555123 Fax: +972-2-6555857