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PubMed2001

Development of a monoclonal sandwich ELISA for the detection of animal and human Escherichia coli O157 strains.

AIMS: Production of a monoclonal antibody (MAb) to Escherichia coli O157 to develop a rapid test using a sandwich ELISA (sELISA) format. METHODS AND RESULTS: A MAb (7A6) was developed to the long-chain lipopolysaccharide of E. coli O157. A sELISA developed with the MAb reacted with 28 bovine and seven human enterohaemorrhagic E. coli (EHEC) O157 strains and also with two enterotoxigenic E. coli O157 strains. Cross-reaction to a rabbit diarrhoeal E.coli O15, Citrobacter freundii, Salmonella urbana and Vibrio cholerae O1 Inaba was detected. CONCLUSION: A MAb-based sELISA to detect E. coli O157 was produced. Its application to field samples is required to fully determine its prospective use for the detection of EHEC O157, to evaluate the non-specific interference of the cross-reacting strains. SIGNIFICANCE AND IMPACT OF THE STUDY: The assay produced is not wholly specific to EHEC O157, but has the potential to be used as a rapid method for screening large numbers of samples for E. coli O157.

Animals↗

PubMed2004

Evaluation of novel beta-ribosidase substrates for the differentiation of Gram-negative bacteria.

AIMS: To synthesize novel substrates for the detection of beta-ribosidase and assess their potential for the differentiation of Gram-negative bacteria. METHODS AND RESULTS: Two novel chromogenic substrates, 3',4'-dihydroxyflavone-4'-beta-D-ribofuranoside (DHF-riboside) and 5-bromo-4-chloro-3-indolyl-beta-D-ribofuranoside (X-riboside) were evaluated along with a known fluorogenic substrate, 4-methylumbelliferyl-beta-D-ribofuranoside (4MU-riboside). A total of 543 Gram-negative bacilli were cultured on media containing either DHF-riboside or X-riboside. Hydrolysis of DHF-riboside or X-riboside resulted in the formation of clearly distinguishable black or blue-green colonies, respectively. Hydrolysis of 4MU-riboside was evaluated in a liquid medium in microtiter trays and yielded blue fluorescence on hydrolysis which was measured using fluorimetry. beta-Ribosidase activity was widespread with 75% of strains, including 85.6% of Enterobacteriaceae, showing activity with at least one substrate. Genera that demonstrated beta-ribosidase activity included Aeromonas, Citrobacter, Enterobacter, Escherichia, Hafnia, Klebsiella, Morganella, Providencia, Pseudomonas, Salmonella and Shigella. In contrast, strains of Proteus spp., Acinetobacter spp., Yersinia enterocolitica, Vibrio cholerae and Vibrio parahaemolyticus generally failed to demonstrate beta-ribosidase activity. CONCLUSIONS: The novel substrates DHF-riboside and X-riboside are effective for the detection of beta-ribosidase in agar-based media and may be useful for the differentiation and identification of Gram-negative bacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report describing the application and utility of chromogenic substrates for beta-ribosidase. These substrates could be applied in chromogenic media for differentiation of Gram-negative bacteria.

Bacterial Typing Techniques↗

PubMed1999

Quorum-sensing cross talk: isolation and chemical characterization of cyclic dipeptides from Pseudomonas aeruginosa and other gram-negative bacteria.

In cell-free Pseudomonas aeruginosa culture supernatants, we identified two compounds capable of activating an N-acylhomoserine lactone (AHL) biosensor. Mass spectrometry and NMR spectroscopy revealed that these compounds were not AHLs but the diketopiperazines (DKPs), cyclo(DeltaAla-L-Val) and cyclo(L-Pro-L-Tyr) respectively. These compounds were also found in cell-free supernatants from Proteus mirabilis, Citrobacter freundii and Enterobacter agglomerans [cyclo(DeltaAla-L-Val) only]. Although both DKPs were absent from Pseudomonas fluorescens and Pseudomonas alcaligenes, we isolated, from both pseudomonads, a third DKP, which was chemically characterized as cyclo(L-Phe-L-Pro). Dose-response curves using a LuxR-based AHL biosensor indicated that cyclo(DeltaAla-L-Val), cyclo(L-Pro-L-Tyr) and cyclo(L-Phe-L-Pro) activate the biosensor in a concentration-dependent manner, albeit at much higher concentrations than the natural activator N-(3-oxohexanoyl)-L-homoserine lactone (3-oxo-C6-HSL). Competition studies showed that cyclo(DeltaAla-L-Val), cyclo(L-Pro-L-Tyr) and cyclo(L-Phe-L-Pro) antagonize the 3-oxo-C6-HSL-mediated induction of bioluminescence, suggesting that these DKPs may compete for the same LuxR-binding site. Similarly, DKPs were found to be capable of activating or antagonizing other LuxR-based quorum-sensing systems, such as the N-butanoylhomoserine lactone-dependent swarming motility of Serratia liquefaciens. Although the physiological role of these DKPs has yet to be established, their activity suggests the existence of cross talk among bacterial signalling systems.

4-Butyrolactone↗

PubMed2003

A molecular phylogeny of enteric bacteria and implications for a bacterial species concept.

A molecular phylogeny for seven taxa of enteric bacteria (Citrobacter freundii, Enterobacter cloacae, Escherichia coli, Hafnia alvei, Klebsiella oxytoca, Klebsiella pneumoniae, and Serratia plymuthica) was made from multiple isolates per taxa taken from a collection of environmental enteric bacteria. Sequences from five housekeeping genes (gapA, groEL, gyrA, ompA, and pgi) and the 16S rRNA gene were used to infer individual gene trees and were concatenated to infer a composite molecular phylogeny for the species. The isolates from each taxa formed tight species clusters in the individual gene trees, suggesting the existence of 'genotypic' clusters that correspond to traditional species designations. These sequence data and the resulting gene trees and consensus tree provide the first data set with which to assess the utility of the recently proposed core genome hypothesis (CGH). The CGH provides a genetically based approach to applying the biological species concept to bacteria.

DNA, Bacterial↗

PubMed2002

Infectious complications in patients undergoing unrelated donor bone marrow transplantation: experience from a single institution.

OBJECTIVE: To analyze the incidence and characteristics of documented infections in patients with hematologic malignancies undergoing unrelated donor bone marrow transplantation (UD-BMT). METHODS: We studied the occurrence of infections in 22 patients with hematologic malignancies or severe aplastic anemia who underwent UD-BMT from April 1990 to December 2000. The median age was 26 years (range 13-46). Acyclovir-ganciclovir, co-trimoxazole, fluconazole-nystatin and ciprofloxacin were administered for anti-infectious prophylaxis. RESULTS: We registered 61 infectious episodes. During the early post-transplant period, there were eight clinically documented infections (CDIs), four cases of fever of unknown origin (FUO), seven cases of bacteremia, two cases of cytomegalovirus (CMV) antigenemia, and one case of CMV disease. In the intermediate period (days 30-100 after BMT), there were nine cases of CMV antigenemia, three bacterial infections, two fungal infections, one case of disseminated toxoplasmosis, and one case of FUO. In the late period (day 100 and later), we documented 13 viral infections, eight bacterial infections, one CDI, and one case of invasive aspergillosis. Infections contributed to death in 10 of 17 patients. Citrobacter bacteremia and sepsis of unknown origin were the main causes of infectious mortality in the early period. Infection was the main cause of death in six of seven patients in the late period. CONCLUSION: A high incidence of life-threatening infections and infection-related mortality was observed. A high rate of CMV infection in the early period, and death caused by multiresistant Gram-negative microorganisms in the late period, were the main findings in this series.

Adolescent↗

PubMed2000

Treatment of sanitary-important bacteria by bacteriocin substance V24 in cattle dung water.

Quantification of sanitary-important bacteria (e.g. Enterobacteriaceae), as well as indicators of environmental contamination, was assessed in samples of cattle dung from 25 cattle farms in 15 north-eastern Slovakia districts. The inhibitory effect of crude bacteriocin extract CBE V24 from Enterococcus faecalis V24 against Listeria monocytogenes Ohio and Yersinia enterocolitica YE85 was examined in cattle dung water with the aim of finding a new way of eliminating the health risk of the animal slurry. The following bacterial groups were quantified: Salmonella spp., Shigella-like spp. , Proteus spp., Enterobacter spp., Citrobacter spp., Pseudomonas spp. , Escherichia coli, Listeria spp., staphylococci, streptococci and enterococci (the average count ranged from 102 up to 104 cfu ml-1). Antagonistic effect of the crude bacteriocin from Enterococcus faecalis V24 in the range of 100-600 Arbitrary units per ml (AU ml-1) was shown against the following bacteria: Enterobacter cloacae, Ent. asburiae, Proteus spp., Salmonella spp., Acinetobacter lwoffi, L. monocytogenes as well as Y. enterocolitica YE85. During tests performed to study the inhibitory effect of the crude bacteriocin CBE V24 (concentration 800, 1600 AU ml-1) against L. monocytogenes Ohio and Y. enterocolitica YE85 in experimentally contaminated cattle dung, a reduction of 2.03 and 1.44 log cfu ml-1, respectively, was already noted after 1 h after crude bacteriocin CBE V24 addition.

Animals↗

PubMedDate not supplied

Kell blood group activity of gram-negative bacteria.

To understand better the relationships between blood-group antigens and bacterial constituents, examples of 23 gram-negative bacteria (representing the 10 genera Citrobacter, Edwardsiella, Enterobacter, Escherichia, Klebsiella, Proteus, Pseudomonas, Salmonella, Serratia, and Shigella) were tested for the presence of Kl-like antigens by hemagglutination-inhibition (HAI) assays against both IgG and IgM anti-Kl. Saline-suspended whole organisms, cell-free culture media, and disrupted organisms were used to test for such antigens in, on, and secreted by the microorganisms examined. Disrupted organisms of an isolate of Shigella sonnei nonspecifically inhibited IgG anti-Kl as well as IgG antibodies of the specificities Kpb, Fya, S, and c. However, only Escherichia coli 0125:B15, subtype 12808, had specific K1-like activity (no activity with other IgG [(k, Kpb, Jka, Fya, S, c] and IgM [A, B, M, P1] antibodies). Disrupted organisms inhibited IgM but not IgG anti-K1 in the HAI assay. A second subtype, E. coli 0125:B15, subtype 12809, exhibited no K1-like activity. These findings support the report of K1 activity in cell-free broth cultures of E. coli 0125:B15 (subtype unspecified). Thus, although not all E. coli 0125:B15 possesses K1-like activity, the finding of such activity in at least one E. coli subtype confirms the idea that bacterial components may play a role in the production of naturally occurring antibodies directed against non-ABO red cell antigens.

Blood Group Antigens↗

PubMed1990

Effects of room-temperature exposure on bacterial growth in stored red cells.

Experiments were performed to determine the effect of room-temperature (RT) exposure on the growth rates of selected bacteria by deliberate contamination of AS-1 packed red cell (RBC) units contained in PL146 plastic bags. Isolates of Staphylococcus aureus, S. epidermidis, Streptococcus faecalis, Pseudomonas aeruginosa, Citrobacter freundii, Enterobacter agglomerans, and Yersinia enterocolitica were inoculated into 3- to 5-day-old packed RBC units. The units were refrigerated at 4 to 6 degrees C for 14 days. On two occasions during this period, one-half of the units were removed from the refrigerator and held at 25 to 26 degrees C for 2 hours. Timed samples taken during the periods at RT revealed stable or decreasing bacterial counts in the majority of exposed units, and in no instance was a marked increase in bacterial growth observed. Samples taken after subsequent prolonged rerefrigeration showed no significant increase in bacterial counts as compared with those in control units that were refrigerated constantly. These results indicate that RT exposure of contaminated RBC units does not result in accelerated bacterial proliferation over a period of 2 hours and that it may, in fact, have a detrimental effect on bacterial growth.

Bacteria↗

PubMed1987

[Etiology of corneal ulcers with special reference to bacterial genesis].

The authors report on 134 patients (141 eyes) seen between May 1982 and December 1985 with corneal ulcers with or without hypopyon. Eight patients (11 eyes) had a facial palsy, 7 (7 eyes) a varicella zoster infection, 1 (2 eyes) a marginal ulcer ("furrow keratitis") associated with collagenosis, 29 (29 eyes) an ulcerative keratitis with endophthalmitis, 1 (2 eyes) a pemphigoid-associated ulcer and 90 (92 eyes) a herpetic infection. Pathogenic bacterial strains were isolated from 20 patients: 10 coagulase-positive Staphylococcus aureus (4 coinfections), 3 Pseudomonas aeruginosa (1 coinfection), 2 Proteus mirabilis (1 coinfection), 2 Escherichia coli and Enterobacter cloacae, Citrobacter freundii and beta-hemolyzing streptococci as well as enterococci in one case each, and non-hemolyzing streptococci and alpha-hemolyzing streptococci in two cases each as coinfections. A comparison of the range of bacterial strains of postoperative endophthalmitis and kerato-/conjunctivitis with bacterial corneal ulcers revealed a high percentage of gram-negative organisms in the latter. Laboratory work-up should include microscopy, agar plating and differentiation as well as antibiotic sensitivity testing and modern immunofluorescent direct techniques. Management includes bactericidal topical and systemic antibiotic regimens as well as surgical procedures if necessary, e.g., perforating tectonic and mini-keratoplasty, and conjunctival flapping followed by lamellar keratoplasty.

Anti-Bacterial Agents↗

PubMed2005

A genomic population genetics analysis of the pathogenic enterocyte effacement island in Escherichia coli: the search for the unit of selection.

Comparative genomic analysis is a powerful tool for understanding the history and organization of complete genomes. The mathematical tools of population genetics combined with genomic analysis provide a powerful approach to dissect heterogeneities in genome evolution. This study presents a hierarchical analysis of the enterocyte and effacement island (35 kb), which is found in the enteropathogenic and enterohemorrhagic strains in Escherichia coli and in Citrobacter rodentium. The locus of enterocyte and effacement in E. coli is considered to be a clonal unit inside a clonal organism and is expected to evolve as a single unit. This analysis examines the clonal assumption by determining genetic diversity, GC content, and the substitution rates at the different functional levels of (i) the complete pathogenic island, (ii) the five operons in which the island is organized, and (iii) for each of the individual 41 genes that comprise the locus. We find that there is a conserved region that is composed of genes that belong to the type III secretion system and that may be products of horizontal transfer. A more diverse region is composed of genes for secreted proteins and genes that we infer to be original components of the E. coli genome. This genetic mosaic seems to be differentially affected by selection and mutation. Our results suggest that recombination and selection may be breaking this structure so that different elements are, at best, weakly coupled in their evolution. These observations suggest that the units of selection are not the complete island, but rather, much smaller units that comprise the island.

Codon↗

PubMed2004

Intimin types alpha, beta, and gamma bind to nucleolin with equivalent affinity but lower avidity than to the translocated intimin receptor.

The outer membrane adhesins of enteropathogenic Escherichia coli, Citrobacter rodentium, and enterohemorrhagic E. coli (EHEC) O157:H7 that mediate attach and efface intestinal lesions are classified as intimin alpha, beta, and gamma, respectively. Each of these intimin types binds to its cognate, bacterially encoded receptor (called Tir for translocated intimin receptor) to promote tight adherence of the organism to the host-cell plasma membrane. We previously reported that gamma intimin of EHEC O157:H7 also bound to a eucaryotic receptor that we determined was nucleolin. The objective of this study was to investigate in vitro and in vivo the interactions of intimins alpha, beta, and gamma with nucleolin in the presence of Tir from EHEC O157:H7. Protein binding experiments demonstrated that intimin of types alpha, beta, and gamma bound nucleolin with similar affinity. Moreover, all three intimin types co-localized with regions of nucleolin expressed on the surface of HEp-2 cells. When intimin alpha, beta, or gamma bound to Tir in vitro, the intimin interaction with nucleolin was blocked. Both Tir and nucleolin accumulated beneath intimin-presenting bacteria that had attached to the surface of HEp-2 cells. Taken together, these findings suggest that nucleolin is involved in bacterial adherence promoted by all intimin types and that Tir and nucleolin compete for intimin during adherence.

Actins↗

PubMed2004

Targeting of enteropathogenic Escherichia coli EspF to host mitochondria is essential for bacterial pathogenesis: critical role of the 16th leucine residue in EspF.

The attachment of enteropathogenic Escherichia coli (EPEC) to host cells and the induction of attaching and effacing (A/E) lesions are prominent pathogenic features. EPEC infection also leads to host cell death and damage to the intestinal mucosa, which is partly dependent upon EspF, one of the effectors. In this study, we demonstrate that EspF is a mitochondrial import protein with a functional mitochondrial targeting signal (MTS), because EspF activity for importing into the mitochondria was abrogated by MTS deletion mutants. Substitution of the 16th leucine with glutamic acid (EspF(L16E)) completely abolished EspF activity. Infection of HeLa cells with wild type but not the espF mutant (DeltaespF) decreased mitochondrial membrane potential (DeltaPsi(m)), leading to cell death. The DeltaPsi(m) decrease and cell death were restored in cells infected with DeltaespF/pEspF but not DeltaespF/pEspF(L16E), suggesting that the 16th leucine in the MTS is a critical amino acid for EspF function. To demonstrate the impact of EspF in vivo, we exploited Citrobacter rodentium by infecting C3H/HeJ mice with DeltaespF(CR), DeltaespF(CR)/pEspF(CR), or DeltaespF(CR)/pEspF(L16E)(CR). These results indicate that EspF activity contributes to bacterial pathogenesis, as judged by murine lethality and intestinal histopathology, and promotion of bacterial colonization of the intestinal mucosa.

Amino Acid Sequence↗

PubMed2004

DNA based classification of food associated Enterobacteriaceae previously identified by Biolog GN Microplates.

Enterobacteriaceae are frequently isolated from food products and it is essential to have methods for correct identification for both food hygiene and epidemiology reasons. Phenotypic methods are not always sufficient and have to be supplemented by DNA based methods. In the present study, 70 strains of Enterobacteriaceae derived from milk, fish and meat that had previously been identified by Biolog GN Microplates were genomically classified together with 15 representative type strains of species of Enterobacteriaceae. The field strains were dominated by Hafnia alvei, Serratia liquefaciens and Rahnella aquatilis. All strains were subjected to temporal temperature gel electrophoresis (TTGE) analysis using amplicons encompassing the V3, V4 and V9 variable regions of the 16S rRNA gene. Selected strains were analysed by ribotyping and partial 16S rDNA sequencing. The type strains were differentiated into 10 different TTGE groups. Two of the groups contained two type strains. Enterobacter aerogenes and Klebsiella planticola were not distinguished due to their identical sequences and Yersinia ruckeri and Citrobacter freundii showed the same migration pattern. The 70 food strains could be differentiated into 14 TTGE groups where 33 strains (47.1%) could be assigned to TTGE groups including type or reference strains. Rahnella strains were dispersed into three TTGE groups of which one group corresponded to Rahnella genomospecies 1 and one to genomospecies 3. The grouping of Rahnella strains was supported by ribotyping and phylogenetic analysis. TTGE can be a useful additional tool for identification on the species level of food related Enterobacteriaceae.

Animals↗

PubMed2003

Bioactivity of secoiridoid glycosides from Centaurium erythraea.

As part of our on-going search for bioactive compounds from Scottish plants, two secoiridoid glycosides, swertiamarin and sweroside, have been isolated from the aerial parts of Centaurium erythraea Rafn (Family: Gentianaceae) by reversed-phase preparative HPLC coupled with a photo-diode-array detector. The structures of these compounds were elucidated unambiguously by UV, FABMS and extensive 1D and 2D NMR spectroscopic analyses and also by comparing experimental data with literature data. Antibacterial, free radical scavenging activities and general toxicity of these glycosides have been assessed. Both compounds inhibited the growth of Bacillus cereus, Bacillus subtilis, Citrobacter freundii and Escherichia coli. While swertiamarin was also active against Proteus mirabilis and Serratia marcescens, sweroside inhibited the growth of Staphylococcus epidermidis. Swertiamarin and sweroside exhibited significant general toxicity in brine shrimp lethality bioassay and the LD50 values were 8.0 microg/ml and 34 microg/ml, respectively, whereas that of the positive control podophyllotoxin, a well known cytotoxic lignan, was 2.79 microg/ml. Chemotaxonomic implications of these compounds in the family Gentianaceae have also been discussed briefly.

Animals↗

PubMed1994

Evaluation of direct disc diffusion susceptibility testing for bacteriuria using diluted urine against standard CDS method.

Consecutive urine specimens with > or = 10(9) organisms/L on microscopy were diluted 1:100 and direct disc diffusion susceptibility tests performed. Subsequently, the standard Calibrated Dichotomous Sensitivity (CDS) test was performed on all isolates. Urines with > 2 Isolates or where growth was < 10(8) colony forming units (CFU)/L were excluded. Only Gram negative organisms were considered. 361 urines were evaluated, 324 with one and 37 with 2 isolates, comprising 255 Escherichia coli, 49 klebsiella, 41 proteus, 29 either citrobacter, enterobacter, providencia, serratia or alcaligenes, and 14 Pseudomonas aeruginosa. There were 2272 organism/antimicrobial test comparisons. A concordance of 98.5% was obtained. The results are considered acceptable for routine clinical use.

Anti-Bacterial Agents↗

PubMed2000

Comparative effects of moxifloxacin and clarithromycin on the normal intestinal microflora.

Twelve healthy male subjects age range 24-40 y participated in the investigation. The trial was divided into 2 35-d periods. The 2 treatment regimens were: (i) 1 x 400 mg moxifloxacin tablet in the morning and 1 placebo tablet in the evening for 7 d; and (ii) 1 x 500 mg clarithromycin tablet in the morning and 1 x 500 mg clarithromycin tablet in the evening for 7 d. Each subject received firstly I treatment regimen and secondly the other treatment regimen. The wash-out period was 6 weeks between the two treatment regimens. Moxifloxacin caused significant decreases of enterococci and enterobacteria during the administration period while the numbers of staphylococci, streptococci, Bacillus and Candida were not affected. No impact on peptostreptococci, lactobacilli, Veillonella, Bacteroides or fusobacteria was observed, while bifidobacteria and clostridia decreased during moxifloxacin administration. The microflora was normalized after 35 d. Clarithromycin caused significant reduction of Escherichia coli while the numbers of enterococci, Enterobacter, Citrobacter, Klebsiella and Pseudomonas increased markedly. No significant changes in the numbers of staphylococci, streptococci, Bacillus and Candida were noticed. In the anaerobic microflora bifidobacteria, lactobacilli and clostridia were suppressed, while no changes in peptostreptococci, Veillonella, Bacteroides and fusobacteria were found. The microflora was normalized in all volunteers after 35 d.

Administration, Oral↗

PubMed2005

Changing bacterial isolates and antibiotic sensitivities of purulent dacryocystitis.

OBJECTIVE: To examine the current spectrum of bacterial isolates in cases of chronic dacryocystitis and dacryoabcess and to determine their antibiotic sensitivities. MATERIALS AND METHODS: We carried out a prospective study in which 39 patients who presented to the outpatient clinic with chronic purulent dacryocystitis or acute dacryoabscess had cultures taken. All patients were antibiotic-free for at least one week prior to culturing. RESULTS: The 39 positive cultures grew 41 bacterial isolates, as two patients grew two species of bacteria; 16 isolates (39%) were Gram-positive and 25 (61%) were Gram-negative. The most common isolates were Pseudomonas (22%), Staphylococcus aureus (13%), Enterobacter (10%), Citrobacter (10%), Streptococcus pneumoniae, E. coli, and Enterococcus (7%). Uncommon Gram-negative bacteria were also cultured: Alcaligenes in two cases (5%), and one case of Stenotrophomonas maltophilia (2.5%). No anaerobic bacteria were isolated. Gram-negative isolates were sensitive to ceftazidime in 95%, ciproxin in 86%, and cefuroxime in 50% of cases, with sensitivity of less than 30% to cephalexin and ampicillin in those tested. All Pseudomonas isolates (100%) were sensitive to ceftazidine, 86% were sensitive to ciprofloxacin, with only 20% being sensitive to ampicillin and 14% to cephalexin. Alcaligenes was resistant to all antibiotics tested with the exception of ceftazidine. CONCLUSION: This study demonstrates a significant change in bacterial flora and antibiotic treatment requirements of purulent dacryocystitis from previously published data. A higher incidence of Gram-negative organisms, particularly Pseudomonas, with resistance to commonly used antibiotics was found. The emergence of rarer highly resistant Gram-negative microorganisms may also indicate a trend in lacrimal sac infections. These findings suggest that the antibiotic treatment protocol before and after lacrimal surgery should be reconsidered in this subgroup of patients.

Adolescent↗

PubMed2005

Changing bacterial isolates and antibiotic sensitivities of purulent dacryocystitis.

PURPOSE: To examine the current spectrum of bacterial isolates in cases of chronic dacryocystitis and dacryoabcess and to determine their antibiotic sensitivities. MATERIALS AND METHODS: We carried out a prospective study in which 39 patients who presented to the outpatient clinic with chronic purulent dacryocystitis or acute dacryoabscess had cultures taken. All patients were antibiotic-free for at least one week prior to culturing. RESULTS: The 39 positive cultures grew 41 bacterial isolates, as two patients grew two species of bacteria. Sixteen isolates (39%) were Gram positive and 25 (61%) were Gram negative. The most common isolates were Pseudomonas (22%), Staphylococcus aureus (13%), Enterobacter (10%), Citrobacter (10%), Streptococcus pneumoniae, Escherichia coli, and Enterococcus (7%). Uncommon Gram-negative bacteria were also cultured: Alcaligenes in 2 cases (5%) and one case of Stenotrophomonas maltophilia (2.5%). No anaerobic bacteria were isolated. Gram-negative isolates were sensitive to ceftazidime in 95%, ciprofloxacin in 86% and cefuroxime in 50%, with a sensitivity of less than 30% to cefalexin and ampicillin in those tested. All Pseudomonas isolates (100%) were sensitive to ceftazidime, 86% were sensitive to ciprofloxacin, while only 20% were sensitive to ampicillin and 14% to cefalexin. Alcaligenes was resistant to all antibiotics tested with the exception of ceftazidime. CONCLUSION: This study demonstrates a significant change in bacterial flora and antibiotic treatment requirements of purulent dacryocystitis from previously published data. A higher incidence of Gram-negative organisms, particularly Pseudomonas, with resistance to commonly used antibiotics was found. The emergence of rarer, highly resistant, Gram-negative microorganisms may also indicate a trend in lacrimal sac infections. These findings suggest that the antibiotic treatment protocol before and after lacrimal surgery should be reconsidered in this subgroup of patients.

Adolescent↗