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PubMed1991

Superoxide dismutases of pathogenic and non-pathogenic Streptococcus suis type 2 isolates.

Pathogenic and non-pathogenic isolates of Streptococcus suis type 2 were screened to determine whether differences in superoxide dismutase (SOD) synthesis could explain the observed differences in their pathogenicity and intracellular fate in macrophages. A single band of SOD activity of similar Rf value was visualised in PAGE gels in all isolates and inhibition studies suggested that the cofactor present was manganese. There was no correlation between specific SOD activity and virulence. It is unlikely, therefore, that SOD produced by S. suis type 2 mediates intracellular survival of pathogenic isolates in macrophages.

Animals↗
PubMed1987

In-vitro anti-microbial susceptibility of clinical isolates of pathogenic bacteria to ten antibiotics including phosphomycin.

The minimum inhibitory concentration (MIC) of ten antibiotics was determined for various bacterial pathogens isolated from clinical specimens in a Lagos hospital. The in-vitro activity of penicillin and tetracycline was not very impressive and a similarity was noticed in the resistance patterns of these two antibiotics, while the activity in vitro of the relatively more toxic aminoglycosides and chloramphenicol was high for Gram-negative rods. Ceftazidime demonstrated the highest activity in vitro against all pathogens studied. Cefoxitin, cefuroxime and phosphomycin demonstrated an impressive activity in vitro. Clindamycin was very active against strains of Staphylococcus aureus. beta-lactamase production amongst these strains was studied and the clinical significance of this and their MIC results are discussed.

Anti-Bacterial Agents↗
PubMed1982

Lack of adherence to epithelial cells by freshly isolated urinary pathogens.

Urinary pathogens isolated from twenty patients who had urinary tract infections (UTI) with or without symptoms were tested for adhesion to normal buccal and uroepithelial cells, and for their ability to agglutinate guinea pig and human erythrocytes. The tests were done on initial isolation and after repeated subculture in urine and nutrient broth. Of the fresh isolates all but one were non-fimbriate and all but one were non-adherent in each test system, but after subculture in broth fourteen of the twenty strains developed fimbriae and seventeen became adherent to buccal cells. Five strains remained non-adherent to uroepithelial cells despite repeated subculture, and there was no correlation between adhesion of the subcultured organisms and clinical severity of UTI. These observations suggest that adherence is not a virulence factor for bacteria once they have entered the urinary tract, and that previous claims for the existence of a correlation between the adherence properties of uropathogens and clinical severity of UTI are unfounded.

Acute Disease↗
PubMedDate not supplied

Factors associated with isolation of pathogenic bacteria from sputum of patients with acute bronchospasm.

Patients with obstructive airways disease (asthma and chronic obstructive airways disease) with an acute exacerbation of symptoms were studied. Those requiring hospitalization were chosen to study the pattern of respiratory pathogens isolated on a supervised sputum culture. Certain variables were studied in a case control design to determine an association with culture positivity.

Acute Disease↗
PubMedDate not supplied

In vitro and in vivo characterization of avian reoviruses. I. Pathogenicity and antigenic relatedness of several avian reovirus isolates.

Pathogenicity, pathogenesis, and antigenic relatedness of four avian reovirus isolates obtained from commercially reared broilers were investigated. Chickens of various ages were inoculated both orally and intratracheally with reovirus. Based on disease signs, mortality, weight depression, tissue lesions, invasiveness, and viral persistence in chickens inoculated at 1 day of age, the isolates were classified as being of low, intermediate, or high pathogenicity. The low-pathogenicity isolate (2177) did not cause mortality, weight depression, or clinical disease. The isolate of intermediate pathogenicity (2035) produced low mortality rates (8%), some weight reduction by 7 weeks postinoculation, and microscopic lesions in the intestine and gastrocnemius tendons. The pathogenic isolates, 2408 and 1733, caused severe clinical disease characterized by stunting, feathering abnormalities, mortality as high as 84%, and microscopic lesions in the liver, intestine, pancreas, and/or gastrocnemius tendon. Highly pathogenic isolates also persisted longer in tissues of infected birds and elicited a more prompt and prolonged antibody response. Birds inoculated at 1 day or 1 week of age were more susceptible to reovirus-induced disease than birds inoculated at 2 weeks, suggesting an age-associated resistance. All isolates produced mortality with equal frequency in embryos. The isolates characterized were found to be antigenically similar based on cross-neutralization and cross-protection studies.

Age Factors↗
PubMed2005

Antimicrobial activity of tigecycline tested against nosocomial bacterial pathogens from patients hospitalized in the intensive care unit.

The antimicrobial activity of tigecycline and selected antimicrobials was evaluated against bacterial pathogens isolated from patients hospitalized in intensive care units (ICUs) worldwide. A total of 9093 isolates were consecutively collected in >70 medical centers in North America (4157), South America (1830), Europe (3034), and the Asia-Australia (72) areas. The isolates were collected from the bloodstream (68.5%), respiratory tract (13.6%), skin/soft tissue (5.5%), and urinary tract (2.0%) infections in the 2000-2004 period, and susceptibility was tested by reference broth microdilution methods. The most frequently isolated pathogens were Staphylococcus aureus (32.1%), Enterococcus spp. (13.7%), coagulase-negative staphylococci (CoNS; 13.0%), Pseudomonas aeruginosa (8.4%), and Escherichia coli (7.9%). All Gram-positive pathogens (5665) were inhibited at < or =1 microg/mL of tigecycline. Resistance to oxacillin was detected in 43.5% of Staphylococcus aureus and in 85.0% of CoNS, and resistance to vancomycin was observed in 18.6% of enterococci. Tigecycline was very active against Enterobacteriaceae (1876 strains tested) with an MIC90 of < or =1 microg/mL, except for Serratia spp. (2 microg/mL). Extended-spectrum beta-lactamase (ESBL) phenotype was detected in 10% of E. coli and 31% of Klebsiella spp., whereas 28% of Enterobacter spp. were resistant to ceftazidime (AmpC enzyme production). These resistance phenotypes did not adversely affect tigecycline activity. Tigecycline and trimethoprim/sulfamethoxazole were the most active compounds against Stenotrophomonas maltophilia (MIC90, 2 and 1 microg/mL respectively). Tigecycline was also active against Acinetobacter spp. (MIC90, 1 microg/mL), but P. aeruginosa showed decreased susceptibility to tigecycline (MIC90, 16 microg/mL). In summary, isolates from ICU patients worldwide showed high rates of antimicrobial resistance. The most alarming problems detected were vancomycin resistance among enterococci, ESBL-mediated beta-lactam resistance and fluoroquinolone resistance among Enterobacteriaceae, and carbapenem resistance among P. aeruginosa and Acinetobacter spp. Tigecycline exhibited potent in vitro activity against most of clinically important pathogenic bacteria (except P. aeruginosa) isolated from ICU patients and may represent an excellent option for the treatment of infections in this clinical environment.

Anti-Bacterial Agents↗
PubMed2005

Relationship between antimicrobial susceptibility of clinical mastitis pathogens and treatment outcome in cows.

OBJECTIVE: To determine whether there was any association between results of in vitro antimicrobial susceptibility testing of pathogens isolated from cows with mild or moderate clinical mastitis and outcome of treatment. DESIGN: Observational study. ANIMALS: 133 cows with mild or moderate mastitis in a single quarter. PROCEDURE: Cows were treated by means of intramammary infusion of pirlimycin (50 mg) in the affected quarter once daily for 2 days; additional intramammary treatments with the same product were administered if the milk continued to appear abnormal. Duration of treatment and days until clinical cure were recorded. Bacterial isolates were tested for antimicrobial susceptibility by means of a broth micro-dilution technique. RESULTS: Environmental streptococci, coliforms, and coagulase-negative Staphylococcus spp were the most commonly isolated pathogens. Duration of treatment and days until clinical cure were not significantly different for cows from which pathogens that were susceptible or resistant to pirlimycin were isolated. Bacteriologic cure rates 14 and 21 days after treatment were not significantly different for cows with mastitis caused by susceptible or resistant bacteria. Similar results were found when data only from cows with mastitis caused by gram-positive isolates were analyzed. CONCLUSIONS AND CLINICAL RELEVANCE: In the present study, differences in clinical outcome for cows with mild or moderate mastitis that could be attributed to differences in results of in vitro susceptibility testing were not identified. The use of in vitro susceptibility testing to guide intramammary mastitis treatment cannot be recommended on the basis of results of this study.

Animals↗
PubMed1991

An epidemiologic and anatomic survey of odontogenic infections.

An 81-month review of patients with infections of odontogenic origin admitted to the oral and maxillofacial surgery service at a county hospital and teaching facility in northeast Ohio is presented. Age, sex, race, etiology, pathogens isolated, admission temperature, and admission white blood cell count were identified and related to the anatomic space(s) encountered. Multispace and single-space infections occurred with equal distribution. In both the multispace and single-space infections, the submandibular and buccal spaces were most frequently involved. Males were affected with single-space infections twice as often as females. An equal distribution among sexes was found in multispace infections. The most common age range for all infections was 25 to 30 years. alpha-Hemolytic streptococci, Bacteroides melaninogenicus, and beta-hemolytic streptococci were the most frequently isolated pathogens. Third molars were the prevalent cause in both multispace and single-space infections that required hospital admission.

Adolescent↗
PubMed2005

Microbiology of middle ear effusions from 292 patients undergoing tympanostomy tube placement for middle ear disease.

OBJECTIVE: Otitis media is one of the most commonly diagnosed childhood illnesses. Ideally, culture directed therapy for otitis media would be available, however, the common approach is to treat infections with antibiotics that cover the most common pathogens. The objective of this study is to describe the pathogens cultured from the middle ear effusions (MEE) of patients that underwent tympanostomy tube placement for middle ear disease, compare these results with previous studies, and assess for trends suggestive of changes in the microbiology of these patients. METHODS: Patients were invited to participate after the decision to place ventilation tubes had been made. A standard anterior-inferior myringotomy was made for placement of the ventilation tube. After myringotomy, patients had their ears suctioned and all effusions were collected for microbiologic analysis. RESULTS: A total of 292 patients were enrolled in the study, a total of 270 MEE samples were taken. Haemophilus influenzae and Moraxella catarrhalis were seen in 24 of 148 (16.2%) and 15 of 148 (10.1%), respectively. Neisseria meningitidis, Staphylococcus aureus and Corynebacterium species were each identified in 11 of the 148 pathogens isolated (7.4%). Streptococcus pneumoniae was identified in 6 of the 148 isolated pathogens (4.1%). CONCLUSION: Despite a high number of non-pathogenic bacteria, and a high number of culture negative effusions, we demonstrated pathogen rates consistent with other reports in the literature. Future directions include using more specific techniques such as PCR to better understand the microbiology of middle ear effusions.

Candida↗
PubMed1984

Role for dual individualization with cefmenoxime.

Cefmenoxime concentration/effect relationships were retrospectively explored for gram-negative bacteria isolated from 14 critical care patients treated for nosocomial pneumonia. The effects of cefmenoxime concentrations on in vitro growth kinetics of 21 isolated pathogens were studied using the Abbott MS-2 Research System, from which a dynamic response concentration was derived. Serum pharmacokinetic profiles were obtained in each patient. These data were used to calculate the in vivo total area under the curve over dynamic response concentration and the time that cefmenoxime concentrations exceeded the dynamic response concentration for each bacteria. The same determinations were made in 18 patients prospectively treated, except that dosage was optimized on the basis of previous mathematical relations to achieve bacterial eradication in four days. This method of dosage optimization is termed dual individualization. Serial cultures of infected tissues were evaluated to determine the number of days to the eradication of bacteria, and the pharmacokinetic and pharmacodynamic variables were used to describe the bacteriologic response of the original pathogen isolated in pretreatment culture. Bacterial eradication rates could be described from cefmenoxime pharmacokinetics in the patient and from the relation between concentration and bacterial inhibition. Patients who were prospectively treated using these retrospectively derived relationships had a predictable day of bacterial eradication. This, in turn, was associated with a shorter duration of treatment (p less than 0.05). The success of prospective dual individualization is encouraging and suggests that more precise optimization of antibiotic dosage can yield a predictable rate of bacterial eradication from the infection site.

Aged↗
PubMed2001

Unit differences in pathogen occurrence arising from the MYSTIC program European database (1997-2000).

The Meropenem Yearly Susceptibility Test Information Collection (MYSTIC) Program is a longitudinal global antimicrobial surveillance study that compares the activity of meropenem and comparator antimicrobial agents against pathogens isolated from intensive care, neutropenic or cystic fibrosis patients, and general wards. Data from the different European MYSTIC Program units (1997-2000) showed that the most prevalent isolates tested overall were methicillin-susceptible Staphylococcus aureus (MSSA; in accordance with study design methicillin-resistant S. aureus was not tested), Pseudomonas aeruginosa and Escherichia coli. In all the unit types, E. coli (approximately 20% having an extended spectrum beta-lactamase phenotype) and MSSA were highly susceptible to meropenem (97-99% susceptibility). Isolates of MSSA showed lower levels of susceptibility to ciprofloxacin (61-77% susceptibility) in both cystic fibrosis and neutropenia patients, and particularly high levels of resistance to ceftazidime (38% susceptibility) in cystic fibrosis units. Ciprofloxacin (54% susceptibility) and gentamicin (46% susceptibility) demonstrated low levels of activity against P. aeruginosa (frequently encountered in cystic fibrosis units). Meropenem and piperacillin/tazobactam were the most active agents against P. aeruginosa in all the unit types. Carbapenems and piperacillin/tazobactam have sustained > 90% susceptibility rates overall against the most frequently isolated pathogens. The analysis of specific units that house patients with a high-risk of contracting antimicrobial-resistant pathogens remains very important for the optimal selection of empiric regimens.

Burkholderia cepacia↗
PubMed1999

Pneumococcal macrolide resistance--myth or reality?

There is no doubt that owing to the prolific use of the macrolides and azithromycin over the past several years, resistance has developed and is increasing in incidence. I believe we should re-evaluate the use of these antibiotics for our patients and consider parameters other than the negative in-vitro results. Firstly, microbiology laboratories should return to the habit of providing the clinician with MIC values for pathogenic isolates rather than generic susceptibility reports ((S)usceptible, (I)ntermediate, (R)esistant) that are based on standard disc diffusion testing. Although agar dilution MIC testing is a bulky and labour intensive practice, it provides the best data when conducted in the appropriate environment. Secondly, and more importantly, these MIC values need to be compared with in-vivo antibiotic pharmacokinetics and pharmacodynamics. Although it is possible to compare MIC values directly with serum concentrations of beta-lactams and aminoglycosides, this is not a valid practice for azithromycin or the macrolides. MICs of azithromycin and the macrolides must be compared with the infection site and phagocytic cell concentrations to determine the utility, or lack thereof, of one of these agents. Whereas azithromycin cellular penetration allows maximal pharmacodynamics potentially even against moderately or highly resistant pneumococci, the macrolides do so less optimally. Although there are no reports of widespread clinical failures resulting from macrolide/azalide resistance in pneumococci, it is expected that such reports will appear once the isolates become consistently highly resistant. This is likely to affect the macrolides, erythromycin and clarithromycin, before the azalide, azithromycin owing to the differences in pharmacokinetics of these drugs. Until then, it will be important to determine the MICs of not just one macrolide, but of all macrolides and azalides for the isolates. This will allow the clinician to make a pharmacokinetically and pharmacodynamically sound choice. By choosing clinical MIC breakpoints of 4-8 mg/L for oral macrolides and < or = 32 mg/L for oral azithromycin, rather than the present standard breakpoints, the clinician can make a macrolide/azalide choice that will optimize the pharmacodynamics of the drug against the isolated pathogen and result in the best possible clinical outcome. Once data concerning the cellular penetration of intravenous formulations of these drugs becomes available, it will be possible to develop clinical breakpoints for these formulations as well. Only through utilizing good antibiotic prescribing practices and by using the drugs appropriately when they are used, can resistance trends be stemmed. In this way, not only does a clinician treat the patient more effectively, but they also extend the antibiotic's useful life.

Anti-Bacterial Agents↗
PubMed2001

Bacteremia in children: etiologic agents, focal sites, and risk factors.

A prospective study was carried out on 210 cases of children under 10 years of age with fever. Cases of gastroenteritis, respiratory tract infections, and suspected sepsis in children seen or admitted to the pediatric hospital were studied. Clinical and microbiological data were recorded in a questionnaire or obtained from patient medical records. Most of the children with septicemia (71.3 per cent) were less than 1 year old. Focal source of bacteremia was gastroenteritis (40.4 per cent), pneumonia or bronchopneumonia (20 per cent), meningitis (7.4 per cent), and urinary tract infections (7.4 per cent). The predominant pathogens isolated from blood or stool specimens were gram-positive bacteria (53.3 per cent), mainly Streptococcus pneumoniae and coagulase-negative Staphylococcus spp. The gram-negative bacteria (45.6 per cent) were mainly Escherichia coli, Klebsiella pneumoniae, Haemophilus influenzae, Neisseria meningitidis, and Yersinia spp. One case of Candida albicans (1.1 per cent) was reported. Pasteurella pneumotropica was reported in two cases for the first time. The mortality rate was 4 per cent, mostly from septicemia cases. Long duration of hospitalization (> 10 days) and parenteral feeding were identified as risk factors. Resistance of the isolated pathogens to several commonly used antibiotics was observed. Empirical treatment with antibiotics is recommended only in life-threatening cases.

Age Distribution↗
PubMed2002

Enteric pathogens, intestinal permeability and nitric oxide production in acute gastroenteritis.

BACKGROUND: Aboriginal children hospitalized with diarrheal disease in northern Australia have high rates of acidosis, hypokalemia and osmotic diarrhea, as well as abnormal small bowel permeability and elevated nitric oxide (NO) production. METHODS: In a study of 291 diarrheal admissions and 84 controls, we examined the relationship of diarrheal severity outcomes with specific enteric pathogens. NO production was measured by urine nitrate plus nitrite excretion on a low nitrate diet, small bowel permeability by the lactulose:rhamnose ratio on a timed blood specimen and stool pathogens by standard microbiologic investigations and PCR. RESULTS: The addition of diagnostic tests for diarrheagenic Escherichia coli to standard stool microbiologic testing increased the rate of specific diagnoses from 53% to 75%, but with multiple pathogens isolated from 34%. The most frequently isolated pathogens from diarrheal patients were enteroaggregative E. coli (28.9%), rotavirus (26.5%), enteropathogenic E. coli (17.2%), Salmonella spp. (10.7%), Cryptosporidium parvum (7.2%) and Strongyloides stercoralis (7.2%). High geometric mean permeability ratios (95% confidence intervals) occurred with rotavirus (19.6; 15.3 to 25.1), enteroaggregative E. coli (21.2; 15.3 to 29.3) and Cryptosporidium (23.0; 15.1 to 35.1) compared with 9.4 (6.8 to 13.1) for no pathogens. NO production was highest for Cryptosporidium (3.7; 2.3 to 6.1) compared with 0.6 (0.4 to 1.1) for no pathogens. Multiple regression analysis revealed significant associations (P < 0.001) for rotavirus with acidosis and osmotic diarrhea, for Strongyloides with wasting and hypokalemia and for Cryptospoidium with severe and prolonged diarrhea. CONCLUSIONS: Cryptosporidium, Strongyloides, rotavirus and enteroaggregative E. coli are important contributors to the severe manifestations of acute gastroenteritis in Australian Aboriginal children.

Animals↗
PubMed1998

Bacteriological comparison of cefixime in patients with noncomplicated urinary tract infection in Spain. Preliminary results.

Clinical failure rates and the overuse of oral antibiotics are particularly acute in the case of non-complicated urinary tract infections (UTIs). Recent preliminary results from a major microbiological study in Spain have indicated significantly increased levels of resistance and insensitivity of isolated pathogens to commonly used antibiotics. Escherichia coli was by far the commonest pathogen isolated. Susceptibility was lowest with amoxicillin plus clavulanic acid, at 65.9% (334 of 507 gram-negative strains isolated). On the other hand, excellent susceptibility was noted with cefixime, corresponding to an MIC of <==4 microg/ml, at 99.2% (504 of 507). The results raise questions about the choice of antibiotics currently used in general practice, and suggest that cefixime may be a better first-line empiric treatment for noncomplicated UTIs.

Amoxicillin↗
PubMed1992

Nosocomial infection and antibiotic utilization in geriatric patients: a pilot prospective surveillance program in skilled nursing facilities.

Prospective surveillance of nosocomial infection was conducted at seven skilled proprietary nursing facilities in Orange County, Calif., USA. The average incidence of facility-acquired infection was 5.2 infections/1,000 patient days. The most common source of infection was urinary tract (47%), followed by respiratory tract (26%) and skin (14%). The four most common pathogens isolated were Proteus spp. (20%), Escherichia coli (17%), Staphylococcus aureus (13%) and Pseudomonas spp. (11%). Trimethoprim-sulfamethoxazole (20%) was the most frequently used antibiotic among all prescriptions, followed by ampicillin (16%) and ciprofloxacin (14%). Among all residents surveyed, 33% received at least one course of antibiotics during the study. Of special significance was the fact that 4 (22%) of the 18 strains of Pseudomonas were gentamicin resistant as were 12 of 80 (15%) of the strains of Enterobacteriaceae. Furthermore, 9 of 29 (31%) strains of Pseudomonas tested were found resistant to norfloxacin as were 15 of 129 (12%) strains of enterobacteriaceae. Susceptibility patterns of the isolated pathogens were similar to those of the acute care hospital. This study indicates that infection continues to be a major problem in the skilled nursing facility and that antibiotic-resistant pathogens will be a challenge for the future.

Adolescent↗
PubMed1992

Collagenase activity in clinical isolates of Entamoeba histolytica maintained in xenic cultures.

Several isolates of pathogenic and non-pathogenic E. histolytica from xenic cultures were tested for their capacity to digest native type I collagen gels. The results demonstrate that the pathogenic isolate HM48:IMSS has a high collagenolytic activity. The non-pathogenic isolates, HM43:IMSS, HM44:IMSS and HM46:IMSS showed significantly lower collagenolytic activity. Six groups showing different degrees of collagenase activity or non-activity were separated from the non-pathogenic isolates by a Percoll gradient. The groups obtained from the pathogenic isolate HM48:IMSS always displayed enzymatic activity.

Animals↗
PubMed1989

Symptoms associated with diarrhoeal illness at San Lazaro Hospital, Manila in 1983 and 1984.

The clinical features associated with various agents of diarrhoeal disease were studied using 2,836 patients admitted to San Lazaro Hospital, Manila. Three general patient groups were considered including single pathogen isolations, "multiple pathogen" isolations, and "no pathogen" isolations. In general, symptoms of diarrhoeal illness were found to be non-specific. However, Shigella flexneri. Vibrio parahemolyticus, and rotavirus were significantly associated with a number of prominent symptoms and could sometimes be predictably diagnosed on clinical grounds, especially when age of the patient was considered. Clinical diagnosis cannot be considered an adequate substitute for laboratory methods; other enteric pathogens can sometimes present with the same symptoms. When appropriate laboratory testing is unavailable, as is often the case in developing countries, symptomatologic diagnosis may be of limited value for the organisms mentioned.

Acute Disease↗