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Two isolates of Pseudomonas aeruginosa lacking characteristic indophenol oxidase were recovered from a sputum specimen. A discussion of the characteristic biochemical tests and antibiograms along with a possible explanation for this phenomenon is presented.
BACKGROUND: Infections are one of the main causes of morbidity and mortality in patients with systemic lupus erythematosus. OBJECTIVE: To analyse urinary tract infection (UTI) risk factors in lupus patients; the influence of these factors on disease activity, organ damage, and disease development; the type and prevalence of UTI; and the micro-organisms involved. METHOD: 86 control subjects and 81 lupus patients were studied prospectively over a 12 month period and examined on five occasions. Epidemiological data and information on urinary symptoms, disease activity (SLEDAI), and organ damage (SLICC/ACR) data were collected. Autoantibodies, complement levels, urine culture, and antibiogram were determined; urological studies were also carried out. SPPS 10.0 and STATA 6.0. were used for statistical analysis. RESULTS: The prevalence of UTI in lupus patients was 36%. Lupus influences the onset of UTI (p = 0.001), regardless of other variables. UTI risk factors in lupus patients were age (p = 0.002), previous cases of UTI (p = 0.0001), antinuclear antibodies (ANA) >1/80 IU/ml (p = 0.022), thrombocytopenia (p = 0.02), and admission to hospital due to UTI (p = 0.002). Leucopenia (p = 0.09) and the weekly administration of methotrexate (p = 0.06) had a bearing on the onset of UTI; disease development (p = 0.99), lupus activity (p = 0.32), and organ damage (p = 0.36) do not. The uropathogen most frequently isolated was E coli (60%). CONCLUSIONS: Lupus patients are likely to have UTI, usually manifesting in the lower tract. They are community acquired, basically caused by E coli, and favoured by age, previous UTI, admissions to hospital due to UTI, thrombopenia, ANA, leucopenia, and methotrexate treatments.
A Gram-negative bacillus isolated from the blood of a leukaemic patient with septicaemia was identified on the basis of common tests as Escherichia coli. However, the organism's antibiogram was atypical of E. coli and led to its re-examination and correct identification as Aeromonas hydrophila. A. hydrophila is sensitive to chloramphenicol and tetracycline, characteristics useful in differentiation from E. coli. A simple test differentiating this organism from the Enterobacteriaceae is the oxidase test. A. hydrophila is oxidase positive.
A comparison was made of the performance of a newly established anaerobic section of a clinical laboratory and the routine diagnostic section in terms of isolation and identification of anaerobic bacteria. Both sections attempted to isolate obligate anaerobes from the same clinical specimens which were not transported in anaerobic containers. Anaerobic and diagnostic sections isolated anaerobes from 35% and 6% respectively of clinical specimens. The use of antibiograms greatly improved the identification of anaerobic organisms.
More than 1750 clinical isolates of klebsiella were collected over a period of six years from two different hospitals and capsular typed by the fluorescent antibody technique. A correlation was made between type and site of isolation. Many types were found to be associated more frequently with one site, which suggested a predilection of some capsular types for certain sites of infection. The site may also be a factor contributing to the virulence of a particular type. A greater antibiotic resistance was often noted in types isolated from their predominant sites; however, antibiograms were not consistent for a type from a given site. The combination of site specificity, resistance, and another 'virulence factor' may all be involved in the determination of a pathogenic strain.
Rectal swabs from 122 patients and 497 environmental swabs from several wards were examined for the presence of Clostridium difficile in order to assess the role of the environment in the spread of this organism. Clostridium difficile was isolated from 6/27 (22.2%) oncology patients and from 8/163 (4.9%) environmental specimens obtained from the oncology unit. Items found positive for C difficile were those subjected to faecal contamination such as commode chairs, bed pans, dust pans, discard bins, the sluice and a disposable bed pan machine. Fourteen of 51 (27.4%) asymptomatic neonates yielded mostly toxigenic C difficile in their stools during their first week of life. Five of 156 (3.2%) specimens taken from inanimate objects in the environment of the neonatal units were positive for C difficile. The organism was also isolated from the hands of a nurse. Similar antibiogram patterns were demonstrated in the strains obtained from the patients and their environment indicating the possible occurrence of cross infection. These results indicate that environmental contamination is important in the spread of C difficile in hospitalised patients and the implementation of isolation procedures may limit that spread.
In an outbreak of diarrhoeal disease in an orthopaedic ward Clostridium difficile was isolated from all six patients with diarrhoea. Attempts were made to type these isolates by means of antibiogram, detection of pre-formed enzymes, analysis of surface proteins by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting, and plasmid profile analysis. This showed that a single strain (type E) indistinguishable by the four distinct methods of typing, was isolated from all six patients at some time during their episodes of diarrhoea. Relapse was caused by the acquisition of a new strain in two patients, and by re-emergence or reacquisition of the original strain in two patients. The immunochemical method was the most sensitive and discriminatory of the typing strategies adopted.
BACKGROUND: Resistance of Helicobacter pylori to the more frequently used antibiotics (metronidazole and clarithromycin) reduces eradication rates even with triple treatment. Determining the antibiogram profile of H pylori can take up to 14 days and delays appropriate treatment. AIMS: To determine the role of screening agar plates for more rapid in vitro susceptibility of H pylori to metronidazole, amoxicillin, and clarithromycin. METHODS: Routine gastric biopsy specimens from 507 dyspeptic patients were inoculated on to 10% lysed blood agar plates containing metronidazole (8 microg/ml), clarithromycin (2 microg/ml), or amoxicillin (0.5 microg/ml). The minimum inhibitory concentration (MIC) of the 90 isolates was determined using the E test. RESULTS: Metronidazole resistance was detected in 28 of 90 isolates by E test and nine of 98 by screening agar. The screening agar detected none of the four clarithromycin resistant isolates detected by the E test. CONCLUSIONS: The screening agar method is not sufficiently sensitive to be used alone.
BACKGROUND: Species confirmation of Neisseria gonorrhoeae is commonly performed with biochemical kits, rely on the activity of the enzyme prolyliminopeptidase (PIP). This enzyme has previously been considered to be almost universally present in N gonorrhoeae. However, increasing numbers of N gonorrhoeae isolates lacking PIP activity have been identified. OBJECTIVES: To investigate the possibility of a widespread transmission of one or several N gonorrhoeae PIP-negative strains among several countries worldwide. METHODS: PIP-negative N gonorrhoeae isolates cultured from 2001 to 2004 in Australia, New Zealand and Scotland were comprehensively characterised and compared with previous data from England and Denmark. All isolates were characterised by antibiotic susceptibility testing, serovar determination, pulsed-field gel electrophoresis (PFGE), opa-typing, sequencing of the entire porB gene and N gonorrhoeae multiantigen sequence typing (NG-MAST). RESULTS: Most (83%) of the viable Australian isolates, and all the New Zealand and Scottish isolates were assigned serovar IB-4, with similar antibiograms, nearly identical porB1b gene sequences, identical (ST210) or highly related (ST292, ST1259) NG-MAST STs, and indistinguishable or related PFGE fingerprints as well as opa-types. The isolates showed characteristics indistinguishable or highly related to the previously described English and Danish outbreak strain. CONCLUSIONS: A comprehensive characterisation indicates a widespread dissemination, mainly among men who have sex with men (MSM), of indistinguishable and highly related genotypes that have evolved from a single N gonorrhoeae PIP-negative serovar IB-4 strain among several countries worldwide. An increased awareness of PIP-negative N gonorrhoeae strains is crucial and changes in the diagnostic strategies may need to be considered.
OBJECTIVE: To evaluate the prevalence and epidemiology of penicillinase producing Neisseria gonorrhoeae (PPNG) and tetracycline resistant N gonorrhoeae (TRNG) in the period 1977-95 in the Netherlands. To compare auxotypes, serovars, and antibiograms of PPNG, non-PPNG, and TRNG. To identify determinants in patient characteristics for the epidemic spread of TRNG/PPNG. METHODS: With respect to the national gonococcal surveillance all PPNG isolates from 30 laboratories over the country in 1977-90 and all gonococcal isolates from five sentinel laboratories (during 1 month per quarter) in 1991-5 were collected. Isolates were auxotyped and serotyped, the susceptibility for various antibiotics was tested and plasmid contents were evaluated. Additional data on PPNG infected individuals were collected retrospectively during a microepidemic of TRNG/PPNG. Univariate and multivariate analyses were performed to identify risk factors for TRNG/PPNG infections. RESULTS: In 1995 an overall high prevalence of PPNG infection (27%) and TRNG among PPNG infection (24%) was found in the Netherlands. Importantly, PPNG were found to have higher MICs for ceftriaxone and ciprofloxacin than non-PPNG; clinically relevant resistance to these antibiotics (or related agents) may emerge first among these strains. The observed diversity of strains (123 auxo/serovar classes since 1988) indicates a continuous introduction of new strains into the community. The epidemic increase of TRNG/PPNG was mainly caused by A/S classes NR/1B-6, PRO/1A-3, and PRO/1A-6, suggesting a clonal spread of a few strains; the rapid spread was associated with transmission in high risk individuals (that is, prostitutes and their clients). CONCLUSION: The prevalence of PPNG in the Netherlands remains high and reduced sensitivity to other antimicrobials was detected among the PPNG strains. This underlines the necessity for a continuous national surveillance of resistance in gonococci including limited epidemiological information.
BACKGROUND: Screening methods for the detection of plasmid-mediated AmpC beta-lactamases are technically demanding. The purpose of this study was to assess screening methods for the detection of these enzymes in clinical isolates of Escherichia coli, Klebsiella pneumoniae and Proteus mirabilis. METHODS: Isolates were selected according to a resistance phenotype consistent with production of an AmpC-type beta-lactamase. Detection of acquired ampC genes was done with a multiplex ampC-PCR and sequencing. The phenotypic detection methods evaluated included visual examination of antibiogram plates to identify the presence of scattered colonies located near the edge of the inhibition halo of cefoxitin, cefotaxime, ceftazidime and aztreonam, and a double-disc synergy test using cloxacillin (500 mg) to inhibit AmpC enzymes. RESULTS: Seventy-seven isolates were selected from among 6,209 isolates recovered. Acquired ampC genes (blaCMY-2, blaDHA-1, blaCMY-4 and blaACC-1) were found in 19 (24.7%) of these isolates, including 14 E. coli, two K. pneumoniae and three P. mirabilis isolates. The differential trait for the presence of colonies in the inhibition halo was 100% sensitive and specific. Similar results were obtained for the cloxacillin test, except for the E. coli isolates in which specificity was 10.3%. CONCLUSION: The phenotypic trait described here can be considered useful for suspecting the presence of these enzymes. The cloxacillin test was only useful in isolates lacking a natural AmpC beta-lactamase.
The etiologic diagnosis of ventilator-associated pneumonia (VAP) should be considered as a microbiological emergency due to its impact on morbidity and mortality. Sampling of the lower respiratory tract (LRT) must be performed before starting or modifying antimicrobial therapy. Surveillance cultures in patients without criteria of VAP are not recommended. There is no evidence of any superiority of bronchoscopic over non-bronchoscopic sampling procedures, but quantitative bacterial cultures are essential to allow colonization to be differentiated from true infection of the LRT. Under these conditions, negative cultures practically rule out bacterial infection or, at least, identify patients who will not benefit from antibiotic therapy or who will require a very short course of treatment. Given that identification and antimicrobial susceptibility testing of microorganisms usually takes up to 3 or 4 days, rapid procedures that provide the clinician with useful information are essential. Rapid information, even if partial or less than perfect, is clearly better for the patient than a perfect but delayed report. Gram stain of LRT secretions is an immediate procedure that can guide management and it has a reasonable correlation with culture results. At present, new antibiogram procedures, performed on direct clinical samples, allow presumptive identification and information on susceptibility to commonly used antibiotics in less than 24 hours after sampling. The impact of using this procedure in clinical practice is currently under research.
Ninety-six clinical isolates of Stenotrophomonas maltophilia were examined with the agar dilution method for susceptibility to 19 antimicrobial drugs. Doxycycline, cotrimoxazole, timentin, ofloxacin, fosfomycin, and piperacillin + tazobactam, in that order, inhibited the majority of strains. All isolates were resistant to nitrofurantoin. Concurrent disk susceptibility (Bauer-Kirby method) testing, using currently valid NCCLS interpretative criteria for Pseudomonas aeruginosa, uncovered a significant incidence of very major (category I), major (category II), and minor (categories III and IV) discrepancies for aminoglycosides, cephalosporins, chloramphenicol, and piperacillin + tazobactam and ticarcillin + clavulanic acid. Therefore, new interpretative criteria indicative of intermediate (I) susceptibility of S. maltophilia to these various antibiotics were proposed. In addition, new intermediate susceptibility criteria were proposed for the two beta-lactam-beta-lactamase inhibitor combinations. It was recommended to exclude ciprofloxacin from test batteries against this microorganism due to the wide scatter of minimal inhibitory concentration values and diameters of inhibition zones; the same was true for polymyxin B. It is hoped that the proposed modified, species-specific criteria will improve the clinical utility of laboratory-generated disk antibiograms with respect to the inherently multiple antibiotic-resistant, opportunistic pathogen S. maltophilia.
Postoperative orchitis increases the morbidity and overall hospital stay after prostatectomy. A retrospective review of our initial series of 174 cases revealed an incidence of 6% which is similar to other studies. We reviewed our bacterial flora and antibiogram and subsequently started a prospective study combining peri-operative ceftriaxone and postoperative ciprofloxacin, which we compared to our previous series where we used perioperative ceftriaxone followed by postoperative gentamicin and ampicillin. There was an abolition of orchitis as a consequence and a significant reduction in the rate of wound infection. We conclude that a combination of ceftriaxone and ciprofloxacin is efficacious in reducing the rate of infective complications following prostatectomy. We recommend the use of these or similar drugs based on local microbial flora.
For over two decades, intraperitoneal administration of vancomycin and an aminoglycoside has been an accepted regimen for the empiric treatment of peritonitis in the peritoneal dialysis patient, until definite identification of the organism has been made. The recent emergence of vancomycin-resistant organisms has been of great concern in many centers. The current treatment recommendation therefore is to use cefazolin in place of vancomycin. We analyzed peritonitis data from January 1, 1996 to June 30, 1997, prior to switching over to cefazolin. Seventy-five percent (27 episodes) in 1997 as compared to 78% in 1996 were due to gram-positive organisms. Twenty-two percent (8 episodes) were due to gram- negative organisms in 1997, 21% in 1996, and 3% (1 episode) due to yeast in 1997, 3% in 1996. Staphylococcus epidermidis (SE) caused 33% of the gram-positive peritonitis episodes in 1997 as compared to 37% in 1996. Twenty-two percent of the gram-positive episodes were due to Staphylococcus aureus (SA) in 1997 and 46% in 1996. Enterococcal infections were 26% in 1997 and 1% in 1996. All of these were confined to only 1 patient. The antibiogram revealed 100% sensitivity of both SA and SE to vancomycin and 100% sensitivity of SA to cefazolin, but only 11% sensitivity of SE to cefazolin. The same patient population had a 48% sensitivity of SE to cefazolin in 1996, showing a sudden and substantial increase in resistance to SE. Even though SE is thought to be a less virulent organism, treating patients with a high probability of being infected by SE with an antibiotic showing 89% resistance is not warranted.
OBJECTIVES: To evaluate the efficacy and acute side effects of ciprofloxacin treatment in newborns who developed nosocomial Pseudomonas aeruginosa infection. METHODS: Intravenous ciprofloxacin treatment was given to 30 newborns who developed nosocomial P. aeruginosa infection as proven by culture antibiogram results. Initial doses of 10 mg/kg/day were given and increased up to 40 mg/kg/day according to clinical response, laboratory and culture results. During therapy, complete white blood cell counts, urinalysis, liver and renal function tests were performed weekly. All patients were examined daily during treatment for possible symptoms of joint toxicity such as erythema and swelling. The patients were evaluated by general physical examination, with special attention to joints, 1 week after discharge. RESULTS: Two of the patients (6.6%) died due to pseudomonas infection, but the bacteria were successfully eradicated in 28 patients (93.4%). Four patients died from other causes. No laboratory abnormality related to ciprofloxacin was observed during treatment. Swelling and hyperemia of the joints were not encountered during treatment and the 1-week period after discharge. Ciprofloxacin-resistant P. aeruginosa isolates were not grown during the study. CONCLUSION: Ciprofloxacin treatment is effective in life-threatening multi-drug-resistant P. aeruginosa infections.
A man was admitted with acute pyelonephritis due to Escherichia coli. Three days prior to the onset of his symptoms his wife presented with a 7-day history of cystitis due to E. coli. Before the wife developed her symptoms the couple were having vaginal intercourse every night, and this continued for the first 3 days of her symptoms. The organisms isolated from the urine of both patients were found to have the same biotype, an identical antibiogram, and the same serotype. The temporal sequence of events and the bacteriological findings strongly suggest the sexual transmission of this organism from the wife to her husband.
A clinical test was carried out on 83 children suffering from infectious diarrhoeal processes who were treated with fosfomycin with the oral and paranteral route. Coproculture was carried out in all the children before the beginning of treatment and in 51 of them it was repeated at the end of treatment. Antibiograms were made on the isolated germs and their MIC to fosfomycin studied. Tolerance and secondary effects of the medicament were also studied. The study was considered insufficient in 13 patients so that the evaluation was based on 70, making 4 failures and 60 clinical cures. Administration of fosfomycin causes the eradication of serotypeable E. coli and is followed by an increase in the number of Proteus sp. and Klebsiella/Enterobacter. The sensitivity of the faecal flora to fosfomycin has been very high, except for the strains of Proteus sp. and Klebsiella/Enterobacter. The accumulative percentage of the MIC to fosfomycin of all the strains isolated shows that more than 75% of them are inhibited at concentrations under 32 mug/ml. Tolerance was good and no secondary effects were observed except for the sporadic rise in the SGPT of the children.