Biomedical subjects
Publications and source records attributed to Z Samra.
A preterm infant, with posterior urethral valves had a mycetoma of the renal pelvis caused by Fusarium species. Prolonged treatment with amphotericin B alone or with flucytosine failed. Combined surgical drainage and medical therapy resulted in full resolution.
OBJECTIVES: Infection with Helicobacter pylori, particularly with strains positive for CagA protein, increases the risk of gastric adenocarcinoma. Few studies have explored the possible association between H. pylori infection and colorectal cancer. This study evaluated whether the seroprevalence of CagA in H. pylori-infected patients affected risk for colorectal cancer independently of H. pylori status. METHODS: In this study, we tested serum IgG antibodies against H. pylori (ELISA) and CagA protein (Western blot assay) in 67 patients with colorectal adenocarcinoma, 36 with gastric adenocarcinoma, 47 with other malignancies (cancer controls), and 45 hospitalized for transesophageal echocardiography (TEE controls). Colonic cancer and gastric cancer patients with H. pylori infection were compared to each control group and to the pooled controls using simple and adjusted analyses. RESULTS: H. pylori infection was noted in 50 colon cancer patients, 31 gastric cancer patients, 31 cancer controls, and 32 TEE controls. In all, 41 (82%), 29 (94%), 11 (35%), and 13 (41%), respectively, of these H. pylori-positive sera expressed CagA reactivity (p < 0.001 for all pairwise comparisons between cases and controls). In the adjusted analysis, infection with H. pylori CagA+ compared to H. pylori CagA- was associated with increased risk for colorectal adenocarcinoma (odds ratio = 10.6; 95% CI = 2.7-41.3; p = 0.001) and gastric adenocarcinoma (odds ratio = 88.1; 95% CI = 6.3-1229.2; p = 0.001). CONCLUSIONS: Among patients infected with H. pylori, CagA+ seropositivity is associated with increased risk for both gastric and colonic cancer. This finding should stimulate additional research into the role of cagA+ H. pylori infection in the development of colorectal cancer.
A new broth-based nonradioactive culture system, MB-Redox (Heipha Diagnostika Biotest, Germany), was compared with the liquid radiometric Bactec 460 TB system and the solid Lowenstein-Jensen (L-J) medium for recovery rate and time to detection of mycobacteria. Of the 605 clinical specimens studied, 100 grew acid-fast bacilli (AFB). The isolation rate for all AFB was 84% for Bactec, 69% for MB-Redox, and 48% for L-J. Eighteen percent of the 100 isolates grew only in Bactec, 10% only in MB-Redox, and 5% only in L-J. The average times to detection of the 100 isolates were 13.2, 17.8, and 28.3 days, respectively, and the mean growth times for the 34 AFB detected by all three media were 13.7, 15.2, and 26.8 days, respectively. Mycobacterium tuberculosis was isolated from 15 clinical samples, with detection times of 16.8 days for Bactec, 18.3 for MB-Redox, and 22.8 days for L-J medium; 10 of these isolates grew in all media, with detection times of 14.2, 16.4, and 18.7 days, respectively. Seven were also positive on direct smear, with detection times of 12.4, 13.7, and 17.7 days. Two of the Mycobacterium tuberculosis isolates were recovered only in Bactec and another one only in L-J medium. Mycobacterium haemophilum grew only in the liquid systems, which provided the special growth factors this bacterium requires. Only the combination of all three systems yielded optimal recovery. MB-Redox gave reliable results, offering the advantages of ready-to-use tubes in which the antibiotic supplement is already incorporated and easy and immediate reading of the results. Since this system does not contain any radioactive substance, results can be confirmed with acid-fast staining and conventional and molecular tests.
In order to enhance current knowledge of nosocomial and community-acquired bacteraemic pneumonia in a single tertiary hospital in Israel, a 7-year study was conducted. Using a computerised database, all patients who had bacteraemic pneumonia from March 1988 to August 1995 were studied. During the study period, pneumonia was the source of bacteraemia in 319 of 4,548 (7%) episodes, occurring in 295 patients; 211 (66%) episodes were community-acquired and 108 (34%) were nosocomial. The microoroganisms isolated most frequently from patients with community-acquired bacteraemic pneumonia were Streptococcus pneumoniae (46%), Staphylococcus aureus (10%) and Haemophilus influenzae (8%); while Pseudomonas spp. (17%), Klebsiella spp. (11%) and Staphylococcus aureus (10%) were isolated most often from the patients with nosocomial bacteraemic pneumonia. The median age of patients was 68 years (range, 0.003-100). The overall mortality was 34%. No significant difference was found between the mortality rates of patients with community-acquired (31%) and nosocomial (40%) bacteraemic pneumonia (P=0.1). Multivariate analysis showed that hypothermia, respiratory failure, impaired consciousness, tracheal intubation, Staphylococcus aureus aetiology, septic shock, inappropriate empiric antibiotic treatment and age significantly increased mortality.
Nocardia farcinica is an emerging pathogen in immunocompromised hosts, accounting for 20% of Nocardia isolates in the USA and 13-44% of isolates in Europe. The case of a 72-year-old lymphoma patient with a laryngeal abscess caused by Nocardia farcinica is presented. The initial clinical manifestation was unilateral vocal cord paralysis, which improved following surgical drainage of the abscess and therapy with imipenem. The English-language literature on human Nocardia farcinica infection is reviewed.
A study of the characterization of the phenotypic patterns of Staphylococcus aureus strains isolated from bovine subclinical mastitis in Israeli dairy herds and their correlation with the severity of the disease was undertaken. A total of 400 chronically S. aureus-infected Israeli-Holstein cows, from 15 dairy herds were included in this study. Based on the results of the biochemical reactions, of the anti-biogram and phage typing, one major type of S. aureus was determined in each herd, its prevalence being between 54 and 100% of the total isolates from that same herd. The majority of the isolates were found to be non-haemolytic (62.7%). The most common phage type was 3/A,3/C,55,71, which was predominant in five herds. In two herds none of the isolates (24) were typable by this set of phages. All isolates were susceptible to methicillin, erythromycin, cephalotin, norfloxacin, trimethoprin-sulphamethoxazole and novobiocin. Most isolates were resistant to penicillin (96.6%) and 52% to oxytetracyclin. Differences in protein patterns between 50 and 36 kDa were found by one-dimensional sodium dodecyl sulphate-polyacrylamide gel electrophoresis. No correlation between any combination of the phenotypic characteristics was found when correlation was done with milk yield and somatic cell count, corresponding to the 6 months before sampling. Otherwise, a positive correlation was found between type of haemolysis and the N-acetyl-beta-glucosaminidase (NAGase) values. In milk from quarters infected with the-non-haemolytic strains, the level of NAGase was significantly lower (P < 0.05) than that from quarters infected with the haemolytic strains (69.7 and 105.9, respectively). However, the level of NAGase activity in the milk of the quarters infected with the non-haemolytic strains was significantly higher (P < 0.05) when compared to the milk of quarters infected with coagulase-negative staphylococci (43.5).
A sharp transition between community-type and hospital-type pathogens at the second or third day of hospital stay is often assumed. This study aimed to test whether such a threshold phenomenon exists for bloodstream infections and to examine the relationship between the proportion of infections caused by hospital-type pathogens and length of stay in the hospital. Blood stream infections were studied in a referral and a university hospital in west Denmark, and a university hospital in central Israel during three study periods (1994-1996, 1992-1995, 1989-1995 in the three hospitals respectively). No threshold effect at 2-3 days stay in the hospital could be demonstrated. However the percentage of Pseudomonas aeruginosa bloodstream infections increased constantly in the three hospitals from 1%, 1% and 7% during the first 2 days to 7%, 4%, and 14% during the third week of hospital stay (P<0.01 for all three comparisons-chi(2)for linear trends). For Candida sp. the increase was from 0%, 2%, 1% during the first 2 days to 3%, 4%, and 9% during the third week, P<0.05. Methicillin-resistant Staphylococcus aureus in Israel increased from 26% of the total number of S. aureus during the first 2 days to 69% during the third week, P<0.0001. For penicillin-resistant S. aureus in Denmark, the percentages were 84% and 100%, P<0.05.The percentage of infections caused by hospital-type pathogens increased almost linearly during the first 3 weeks of hospital stay, with no threshold effect. This trend should be taken into account when prescribing empirical therapy for nosocomial infections.
Pre-existing renal insufficiency serves as a common risk factor in the development of acute renal failure. Acute renal failure is a common finding in patients with bacteremia and is associated with poor prognosis. A total of 2722 consecutive patients 18 years old or older, fulfilling strike criteria of bacteremia or fungemia were prospectively evaluated to establish the prognostic importance of pre-existing renal insufficiency in bacteremic patients. They were classified according to serum creatinine levels upon admission into three groups. 915 patients had normal creatinine levels (< or = 1.0 mg/dL), 1528 had mild to moderate renal failure (creatinine 1.1-3 mg/dL) and 279 patients had severe renal failure upon admission (creatinine > 3.0 mg/dL). Mild to severe renal failure upon admission was associated with old age, male gender, diabetes mellitus, ischemic heat disease, hypertension and congestive heart failure. The serum albumin in patients with severe renal failure was significantly low, with a mean of 2-9 mg/dL. Urinary tract infections were more prevalent in patients with mild to severe renal failure, while intravenous line infections, bacterial endocarditis and soft and skin tissue infections were more common in patients with normal renal function. In the 279 patients with severe renal failure the mortality rate was significantly higher (50%) compared to patents with mild to moderate renal failure and patients with normal renal function (21% and 26% respectively, p = 0.0001). Multiple regression analysis revealed that pre-existing serum creatinine > 3 mg/dL was significantly associated with death attributable to bacteremia (OR = 1.7, 95% CI 1.0-2.7). In conclusion, adult bacteremic patients with pre-existing serum creatinine above 3 mg/dL upon admission are at increased risk of mortality due to bacteremia than patients with normal or mild to moderate renal failure.
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In a retrospective study, 80 episodes of nontyphoid salmonella (NTS) bacteremia in children were compared with 55 episodes in adults over a 10-year period. The study disclosed major differences in the predisposition, clinical presentation, and outcome as well as the microbiology of NTS bacteremia in relation to age. Adults were more likely than children to have predisposing diseases (95% vs. 15%, respectively; P < .0001) and to receive prior medications (95% vs. 23%, respectively; P < .0001), particularly immunosuppressive agents (58% vs. 5%, respectively; P < .0001). In most adults (67%), NTS infection presented as a primary bacteremia and was associated with a high incidence of extraintestinal organ involvement (34%) and a high mortality rate (33%). In children, NTS bacteremia was usually secondary to gastroenteritis (75%) and caused no fatalities. Although group D Salmonella (78%) and the serovar Salmonella enteritidis were the predominant isolates from adults, the emergence of infections due to group C Salmonella (46%) and the serovar Salmonella virchow in children was noted.
Acid-fast bacilli from pediatric patients with lymphadenopathy were detected in the BACTEC radiometric system and in MB Redox broth, but not on Löwenstein Jensen medium. PCR amplification identified the isolates as Mycobacterium haemophilum, which has special nutrition requirements (iron supplements) for growth. Suitable culture medium ensures optimal recovery of this microorganism, avoiding underdiagnosis.
Two patients with rapidly progressive necrotizing fasciitis of a lower extremity due to Staphylococcus aureus as a single pathogen are described. In both patients the portal of entry was attributed to needle puncture (intra-articular injection and intravenous catheter, respectively), followed by bacteremia. Necrotizing fasciitis occurred in a site remote from the needle puncture, suggesting metastatic infection. One patient developed toxic shock syndrome and the other a sunburn-like rash and erythematous mucosae with strawberry tongue. One patient died, and the other required above-knee amputation due to secondary infectious complications. Staphylococcus aureus may mimic the presentation of invasive group A streptococcal infections. A history of needle puncture should alert the physician to the possibility of Staphylococcus aureus infection.
OBJECTIVES: To test whether empirical antibiotic treatment that matches the in vitro susceptibility of the pathogen (appropriate treatment) improves survival in patients with bloodstream infections; and to measure the improvement. DESIGN: Observational, prospective cohort study. SETTING: University hospital in Israel. SUBJECTS: All patients with bloodstream infections detected during 1988-94. INTERVENTIONS: None. MAIN OUTCOME MEASURES: In-hospital fatality rate and length of hospitalization. RESULTS: Out of 2158 patients given appropriate empirical antibiotic treatment, 436 (20%) died, compared with 432 of 1255 patients (34%) given inappropriate treatment (P = 0.0001). The median durations of hospital stay for patients who survived were 9 days for patients given appropriate treatment and 11 days for patients given inappropriate treatment. For patients who died, the median durations were 5 and 4 days, respectively (P < 0.05), for both comparisons. In a stratified analysis, fatality was higher in patients given inappropriate treatment than in those given appropriate treatment in all strata but two: patients with infections caused by streptococci other than Streptococcus gr. A and Streptoccocus pneumoniae (odds ratio (OR) of 1.0, 95% confidence interval (95% CI) 0.4-2.5); and hypothermic patients (OR = 0.9, 95% CI = 0.3-2.4). Even in patients with septic shock, inappropriate empirical treatment was associated with higher fatality rate (OR = 1.6, 95% CI = 1.0-2.7). The highest benefit associated with appropriate treatment was observed in paediatric patients (OR = 5.1, 95% CI = 2.4-10.7); intra-abdominal infections (OR = 3.8, 95% CI = 2.0-7.1); infections of the skin and soft tissues (OR = 3.1, 95% CI = 1.8-5.6); and infections caused by Klebsiella pneumoniae (OR = 3.0, 95% CI = 1.7-5.1) and S. pneumoniae (OR = 2.6, 95% C = 1.1-5.9). On a multivariable logistic regression analysis, the contribution of inappropriate empirical treatment to fatality was independent of other risk factors (multivariable adjusted OR = 1.6, 95% CI = 1.3-1.9). CONCLUSION: Appropriate empirical antibiotic treatment was associated with a significant reduction in fatality in patients with bloodstream infection.
CHROMagar Orientation, a new chromogenic medium, was evaluated for the detection and differentiation of gram-positive and gram-negative pathogenic microorganisms in 900 urine samples from hospitalized patients. Performance characteristics of the medium were evaluated in comparison to those of 5% sheep blood and MacConkey agars by direct inoculation of the urine samples on the three media. Four gram-negative and two gram-positive strains as well as one yeast control strain from the American Type Culture Collection were used to ensure quality control. CHROMagar Orientation succeeded in detecting all the urine pathogens that were detected by the reference media, including gram-negative bacilli, staphylococci, streptococci, and yeasts. Colony color and morphology on CHROMagar Orientation accurately differentiated Escherichia coli, Proteus mirabilis, Proteus vulgaris, Pseudomonas aeruginosa, and Acinetobacter spp. Owing to the similarity in the pigmentation produced by Klebsiella, Enterobacter, and Citrobacter isolates, the medium failed to distinguish among them; however, these isolates were easily recognized as coliforms because of their metallic blue coloration. Staphylococci were clearly perceptible: S. aureus and S. epidermidis grow in regular-size colonies that range from opaque white to yellowish, and S. saprophyticus produces opaque pink colonies. All streptococcus strains, including those from groups B and C, were detected. They grow as undifferentiated flat dry diffused colonies, and additional tests were required for identification. Enterococci were easily discriminated by their strong turquoise pigmentation and their typical growth on the agar's surface. Yeast grow in typical creamy wet convex colonies. The accuracy of antibiotic susceptibility determinations according to standard methods was also tested by picking isolates directly from CHROMagar Orientation. The results showed excellent correlation with those obtained with microorganisms picked from reference media. Owing to the ease in differentiating mixed flora on CHROMagar Orientation, antimicrobic susceptibility tests were performed directly from primary isolates in all cases without the need for subcultures.
The most common cause of cellulitis is streptococci. Coagulase-negative staphylococci and gram-negative bacteria, such as Serratia spp., Proteus spp., and other Enterobacteriaceae may produce cellulitis in the immunocompromised patient. We report a case of Citrobacter diversus-induced cellulitis, resembling streptococcal infection, in a patient with multiple myeloma.
In order to determine the epidemiology, microbiology, and outcome of bacteraemia originating in the urinary tract in hospitalised patients, a prospective study was conducted in a large general hospital in Israel. Data from all patients with bacteraemia were collected prospectively, and a subgroup of patients with bacteraemia secondary to urinary tract infection was analysed. There were 702 episodes of bacteraemia secondary to urinary tract infection during a five-year period (33.9% of all episodes of bacteraemia). The mean age of the patients was 76 years, and the male:female ratio was 0.9:1.0. The most common pathogens were Escherichia coli (52%), Klebsiella spp. (14%), and Proteus spp. (9%). Pseudomonas spp. were isolated from 8% of all patients, from 19% of those who had received antibiotics, and from 15% of males. Enterococcus spp. were isolated from 4% of males but from no females. Five percent of the episodes were polymicrobial, and 16% of the infections were hospital acquired. On logistic multivariate regression analysis, predictors of mortality were: hospitalisation in a medical department, hospital-acquired infection, inappropriate empiric antibiotic treatment, presence of decubitus ulcer(s), respiratory or renal failure, and elevated urea and decreased albumin levels.
The aim of the present study was to test whether the combination of a beta-lactam drug plus an aminoglycoside has advantage over monotherapy for severe gram-negative infections. Of 2,124 patients with gram-negative bacteremia surveyed prospectively, 670 were given inappropriate empirical antibiotic treatment and the mortality rate in this group was 34%, whereas the mortality rate was 18% for 1,454 patients given appropriate empirical antibiotic treatment (P = 0.0001). The mortality rates for patients given appropriate empirical antibiotic treatment were 17% for 789 patients given a single beta-lactam drug, 19% for 327 patients given combination treatment, 24% for 249 patients given a single aminoglycoside, and 29% for 89 patients given other antibiotics (P = 0.0001). When patients were stratified according to risk factors for mortality other than antibiotic treatment, combination therapy showed no advantage over treatment with a single beta-lactam drug except for neutropenic patients (odds ratio [OR] for mortality, 0.5; 95% confidence interval [95% CI], 0.2 to 1.3) and patients with Pseudomonas aeruginosa bacteremia (OR, 0.7; 95% CI, 0.3 to 1.8). On multivariable logistic regression analysis including all risk factors for mortality, combination therapy had no advantage over therapy with a single beta-lactam drug. The mortality rate for patients treated with a single appropriate aminoglycoside was higher than that for patients given a beta-lactam drug in all strata except for patients with urinary tract infections. When the results of blood cultures were known, 1,878 patients were available for follow-up. Of these, 816 patients were given a single beta-lactam drug, 442 were given combination treatment, and 193 were given a single aminoglycoside. The mortality rates were 13, 15, and 23%, respectively (P = 0.0001). Both on stratified and on multivariable logistic regression analyses, combination treatment showed a benefit over treatment with a single beta-lactam drug only for neutropenic patients (OR, 0.2; 95% CI, 0.05 to 0.7). In summary, combination treatment showed no advantage over treatment with an appropriate beta-lactam drug in nonneutropenic patients with gram-negative bacteremia.
BACKGROUND: It has been established that lack of circumcision increases the risk of urinary tract infection in infants. During the first six months, the presence of foreskin is associated with a greater quantity and a higher concentration of uropathogens in the periurethral area. Very little is known about this association in older males. OBJECTIVE: To compare the periurethral bacteriology of uncircumcised healthy males of more than one year of age. METHODS: The periurethral area of 125 uncircumcised and 46 circumcised healthy males (mean age, 26.5 and 28.3 years, respectively) was swabbed and cultured for facultative and anaerobic bacteria, genital mycoplasmas and Chlamydia trachomatis. RESULTS: Facultative Gram positive cocci predominated in both groups (62% and 80%, respectively). Pure culture of facultative Gram negative rods was more common in uncircumcised males (17% v 4% in circumcised males, p = 0.01). Streptococci, strict anaerobes and genital mycoplasmas were found almost exclusively in uncircumcised males of more than 15 years of age. No case of C trachomatis was identified. CONCLUSIONS: The higher prevalence of potential uropathogens in the subpreputial space is in accordance with a previous finding of increased risk of urinary tract infection in uncircumcised young men. Our results also support the role of the prepuce as a reservoir for sexually transmitted organisms.