Co-exposure risks of pesticides residues and bacterial contamination in fresh fruits and vegetables under smallholder horticultural production systems in Tanzania.

This study was carried out to investigate the risks of simultaneous exposure to pesticide residues and bacteria contaminants in locally produced fresh vegetables and vegetables in Tanzania. A total of 613 samples were analyzed for pesticide residues, out of which 250 were also analyzed for bacterial contamination. Overall, 47.5% had pesticide residues, 74.2% exceeded Maximum Residue Levels (MRLs). Organophosphorus (95.2%), organochlorines (24.0%), pyrethroids (17.3%), and carbamates (9.2%) residues dominated. MRL values were mostly exceeded in tomatoes, onions, watermelons, cucumbers, Chinese cabbage, and sweet paper. Tetramethrin (0.0329-1.3733 mg/kg), pirimiphos-methyl (0.0003-1.4093 mg/kg), permethrin (0.0009-2.4537 mg/kg), endosulfan (beta) (0.0008-2.3416 mg/kg), carbaryl (0.0215-1.5068 mg/kg), profenofos (0.0176-2.1377 mg/kg), chlorpyrifos (0.0004-1.2549 mg/kg) and dieldrin (0.0011-0.5271 mg/kg) exceeded MRLs. The prevalence of bacteria contamination was high (63.2%). Enterobacter (55.6%) Pseudomonas aeruginosa (32.4%), E. coli (28.2%), Citrobacter (26.8%), Klebsiella oxytoca (14.8%), and Salmonella (7.7%) were isolated. Furthermore, 46.4% tested positive for both pesticide residues and bacterial contaminants. Vegetables from farms (60.7%) contained more dual contaminants than market-based vegetables (41.8%). This may have resulted from excessive pesticide use and unhygienic handling of fresh fruits and vegetables at production level. Binary logistic regression showed that fresh fruits and vegetables with pesticide residues were 2.231 times more likely to have bacteria contaminants (OR: 2.231; 95% CI: 0.501, 8.802). The contamination levels of pesticide residues and bacterial contaminants could be perceived as a serious problem as most fresh fruits and vegetables recorded values of pesticide residues far above the MRLs with pathogenic bacteria isolated in higher proportions. MRLs was higher in most vegetables consumed raw or semi-cooked such as watermelons, carrots, cucumber, tomatoes, onion and sweet paper. There is an urgent need to develop pesticide monitoring and surveillance systems at farmer level, educating farmers and promoting the use of greener pesticides to mitigate the health effects of pesticides and bacterial contaminants.

Infecção de trato urinário inferior por Citrobacter sp em cadela com hipoadrenocorticismo / Citrobacter sp lower urinary tract infection in a bitch with hypoadrenocorticism

Citrobacter sp. é um microrganismo frequentemente encontrado em vagina de cadelas, mas corresponde a menos de 3% do total de microrganismos isolados em urocultura. O hipoadrenocorticismo (HA) é uma doença endócrina incomum e que leva a poliúria e hipostenúria. O objetivo deste trabalho é relatar o caso de uma fêmea da espécie canina, da raça Teckel, 11 anos, atendida com queixa de urina de odor alterado há vários dias, além de vômito, diarreia e inapetência há três dias, e poliúria e polidipsia há 2 meses, com histórico de tratamento anterior com mitotano para hiperadrenocorticismo. O diagnóstico foi de ITU por Citrobactersp., além de HA iatrogênico. Como destaques nos exames, relação sódio:potássio de 22,6 foi observada, sugestiva de HA, que foi confirmado por teste de estimulação com ACTH, além de urina inicialmente hipostenúrica (densidade 1,006), o que pode ser atribuído ao washout medular renal devido à hiponatremia causada pelo hipoadrenocorticismo. O tratamento foi feito com amoxicilina associada a ácido clavulânico por 20 dias, além da terapia específica para HA com prednisona e fludrocortisona, que foi continuado. A paciente recuperou-se bem, a densidade urinária aumentou após início do tratamento para HA e não houve recidiva da ITU em período de acompanhamento de 8 meses. Acredita-se que a baixa densidade urinária causada pelo HA tenha sido fator essencial para a ocorrência da ITU por Citrobacter.

Citrobacter sp. is a normal constituent of bitches' vagina, but it is related to less than 3% of total isolated microorganism in uroculture. Hypoadrenocorticism (HA) is an endocrine disease uncommonly diagnosed that leads to polyuria and hypostenuria. The aim of this work is report the case of a Teckel bitch, 11 years old, attended with complaint of altered urinary smell for several days, besides vomiting, diarrhea and inappetence for three days, and polyuria and polydispsia for two months, with previous mitotane treatment for hyperadrenocorticism. The diagnosis was Citrobacter UTI, besides iatrogenic HA. The most important exam results include sodium:potassium ratio of 22.6, suggestive of HA, that was confirmed by ACTH stimulation test. Besides, hypostenuria (urinary specific gravity ­ USG - of 1.006) was noted, attributed to renal medular washout due to hyponatremia seen in HA. Therapy comprised amoxicillin associated with clavulanic acid for 20 days, in addition to specific therapy for AH with prednisone and fludrocortisone. The patient recovery well, USG increased after the beginning of the treatment for HA and there was no UTI reinfection for a 8 month period. It is believed that low USG due to HA was essential for the occurrence of Citrobacter UTI.

Infecção de trato urinário inferior por Citrobacter sp em cadela com hipoadrenocorticismo / Citrobacter sp lower urinary tract infection in a bitch with hypoadrenocorticism

Citrobacter sp. é um microrganismo frequentemente encontrado em vagina de cadelas, mas corresponde a menos de 3% do total de microrganismos isolados em urocultura. O hipoadrenocorticismo (HA) é uma doença endócrina incomum e que leva a poliúria e hipostenúria. O objetivo deste trabalho é relatar o caso de uma fêmea da espécie canina, da raça Teckel, 11 anos, atendida com queixa de urina de odor alterado há vários dias, além de vômito, diarreia e inapetência há três dias, e poliúria e polidipsia há 2 meses, com histórico de tratamento anterior com mitotano para hiperadrenocorticismo. O diagnóstico foi de ITU por Citrobacter sp., além de HA iatrogênico. Como destaques nos exames, relação sódio:potássio de 22,6 foi observada, sugestiva de HA, que foi confirmado por teste de estimulação com ACTH, além de urina inicialmente hipostenúrica (densidade 1,006), o que pode ser atribuído ao washout medular renal devido à hiponatremia causada pelo hipoadrenocorticismo. O tratamento foi feito com amoxicilina associada a ácido clavulânico por 20 dias, além da terapia específica para HA com prednisona e fludrocortisona, que foi continuado. A paciente recuperou-se bem, a densidade urinária aumentou após início do tratamento para HA e não houve recidiva da ITU em período de acompanhamento de 8 meses. Acredita-se que a baixa densidade urinária causada pelo HA tenha sido fator essencial para a oco

Citrobacter sp. is a normal constituent of bitches’ vagina, but it is related to less than 3% of total isolated microorganism in uroculture. Hypoadrenocorticism (HA) is an endocrine disease uncommonly diagnosed that leads to polyuria and hypostenuria. The aim of this work is report the case of a Teckel bitch, 11 years old, attended with complaint of altered urinary smell for several days, besides vomiting, diarrhea and inappetence for three days, and polyuria and polydispsia for two months, with previous mitotane treatment for hyperadrenocorticism. The diagnosis was Citrobacter UTI, besides iatrogenic HA. The most important exam results include sodium:potassium ratio of 22.6, suggestive of HA, that was confirmed by ACTH stimulation test. Besides, hypostenuria (urinary specific gravity – USG - of 1.006) was noted, attributed to renal medular washout due to hyponatremia seen in HA. Therapy comprised amoxicillin associated with clavulanic acid for 20 days, in addition to specific therapy for AH with prednisone and fludrocortisone. The patient recovery well, USG increased after the beginning of the treatment for HA and there was no UTI reinfection for a 8 month period. It is believed that low USG due to HA was essential for the occurrence of Citrobacter UTI.

Antibiotic Resistance, Virulence Factors, Phenotyping, and Genotyping of Non-Escherichia coli Enterobacterales from the Gut Microbiota of Healthy Subjects.

Non-Escherichia coli Enterobacterales (NECE) can colonize the human gut and may present virulence determinants and phenotypes that represent severe heath concerns. Most information is available for virulent NECE strains, isolated from patients with an ongoing infection, while the commensal NECE population of healthy subjects is understudied. In this study, 32 NECE strains were isolated from the feces of 20 healthy adults. 16S rRNA gene sequencing and mass spectrometry attributed the isolates to Klebsiella pneumoniae, Klebsiella oxytoca, Enterobacter cloacae, Enterobacter aerogenes, Enterobacter kobei, Citrobacter freundii, Citrobacter amalonaticus, Cronobacter sp., and Hafnia alvei, Morganella morganii, and Serratia liquefaciens. Multiplex PCR revealed that K. pneumoniae harbored virulence genes for adhesins (mrkD, ycfM, and kpn) and enterobactin (entB) and, in one case, also for yersiniabactin (ybtS, irp1, irp2, and fyuA). Virulence genes were less numerous in the other NECE species. Biofilm formation was spread across all the species, while curli and cellulose were mainly produced by Citrobacter and Enterobacter. Among the most common antibiotics, amoxicillin-clavulanic acid was the sole against which resistance was observed, only Klebsiella strains being susceptible. The NECE inhabiting the intestine of healthy subjects have traits that may pose a health threat, taking into account the possibility of horizontal gene transfer.

Resistance Trends and Epidemiology of Citrobacter-Enterobacter-Serratia in Urinary Tract Infections of Inpatients and Outpatients (RECESUTI): A 10-Year Survey.

Background and objectives: Urinary tract infections (UTIs) are the third most common infections in humans, representing a significant factor of morbidity, both among outpatients and inpatients. The pathogenic role of Citrobacter, Enterobacter, and Serratia species (CES bacteria) has been described in UTIs. CES bacteria present a therapeutic challenge due to the various intrinsic and acquired resistance mechanisms they possess. Materials and Methods: The aim of this study was to assess and compare the resistance trends and epidemiology of CES pathogens in UTIs (RECESUTI) in inpatients and outpatients during a 10-year study period. To evaluate the resistance trends of isolated strains, several antibiotics were chosen as indicator drugs based on local utilization data. 578 CES isolates were obtained from inpatients and 554 from outpatients, representing 2.57 ± 0.41% of all positive urine samples for outpatients and 3.02 ± 0.40% for inpatients. E. cloacae was the most prevalent species. Results: The ratio of resistant strains to most of the indicator drugs was higher in the inpatient group and lower in the second half of the study period. ESBL-producing isolates were detected in 0-9.75% from outpatient and 0-29.09% from inpatient samples. Conclusions: Resistance developments of CES bacteria, coupled with their intrinsic non-susceptibility to several antibiotics, severely limits the number of therapeutic alternatives, especially for outpatients.

Molecular characterization and antimicrobial resistance profile of atypical Citrobacter gillenii and Citrobacter sp. isolated from diseased rainbow trout (Oncorhynchus mykiss).

AIM: Over the last decade, Citrobacter species have been responsible for infections in fish and many species and also new Citrobacter species have been identified. In this study, molecular identifications and the phenotypic and genotypic antimicrobial-resistance characteristics of atypical and typical Citrobacter species were determined. MATERIALS AND METHODS: Seven Citrobacter isolates were investigated from rainbow trout of different lengths with signs of disease. Biochemical characteristics were determined using conventional tests and rapid test kits; moreover, molecular identifications were conducted with 16S rRNA and the gyrB housekeeping gene region. The sequencing results obtained from the gyrB gene region were deposited in the GenBank database and compared with isolates from different countries that were registered in the database. Resistances to florfenicol, sulfonamides, and tetracycline antimicrobials were determined using the broth micro dilution method, and molecular resistance genes against these antimicrobials were identified. All detected resistance genes were confirmed by sequence analyses. RESULTS: It was determined that three of the Citrobacter species with biochemical characteristics were atypical and showed oxidase-positive reactions. All the Citrobacter species were identified as Citrobacter sp. using the 16S rRNA gene; three isolates were identified as Citrobacter gillenii and four as Citrobacter sp. based on gyrB gene sequence analysis. Some isolates were found in the same group as other countries' isolates in the GenBank database, while isolates with high identities were found in different genogroups. All isolates were found to be phenotypically resistant to sulfamethoxazole and susceptible to tetracycline; these isolates' resistance genes included sulI, tetA, tetB, and tetD.

A cost-saving strategy for processing isolated uropathogens in community-acquired urinary tract infections.

Outpatient urine samples are among the most commonly processed in a microbiology laboratory, which involves a high economic burden. The aim of this study was compare cost and efficiency to process uropathogens between MicroScan system (2010-2011) versus a chromogenic medium and the disk diffusion method (2013-2014). In the first period, a total 9918 bacterial populations were isolated from urine samples. Annual estimated costs during 2010 and 2011 for processing were EUR 53,818 and EUR 57,306, respectively (EUR 111,124 total). In the second period, a total 11,728 bacterial isolates were processed, with annual estimated costs of EUR 21,078 and EUR 23,248, respectively (EUR 44,326 total). We included the cost for a laboratory technician (252h worked per year), estimated at EUR 2500 per year. The mean estimated savings were EUR 66,797 (60%).The identification by chromogenic media and antibiotic susceptibility patterns by disk diffusion method was similar to MicroScan in both study periods. Only some isolated Citrobacter spp., Enterobacter spp., Morganella morganii, and Providencia spp. were misidentified. The strategy reported here did not affect the quality of the results and yielded substantial cost savings.

Epithelial Histone Deacetylase 3 Instructs Intestinal Immunity by Coordinating Local Lymphocyte Activation.

Mucosal tissues are constantly in direct contact with diverse beneficial and pathogenic microbes, highlighting the need for orchestrating complex microbial signals to sustain effective host defense. Here, we show an essential role for intestinal epithelial cell expression of histone deacetylase 3 (HDAC3) in responding to pathogenic microbes and activating protective innate immunity. Mice lacking HDAC3 in intestinal epithelial cells were more susceptible to Citrobacter rodentium when under tonic stimulation by the commensal microbiota. This impaired host defense reflected significantly decreased IFNγ production by intraepithelial CD8+ T cells early during infection. Further, HDAC3 was necessary for infection-induced epithelial expression of the IFNγ-inducing factor IL-18, and administration of IL-18 restored IFNγ activity to resident CD8+ T cells and reduced infection. Thus, HDAC3 mediates communication between intestinal epithelial cells and resident lymphocytes, revealing that epithelial priming by an epigenetic modifier may direct mucosal regulation of host defense against pathogenic microbes.

Citrobacter braakii Bacteremia: Case Report and Review of the Literature.

Bacteremia is frequently caused by gram-positive organisms such as Staphylococcus aureus or ß hemolytic streptococci. While there is adequate information for the diagnosis and management of these common bacteria, less information is available to address bacteremia that is caused by uncommon bacteria such as Citrobacter. Citrobacter species are gram-negative bacilli that have been noted to cause infections in immune compromised patients. The re-speciation of Citrobacter by its varied genetic composition has produced 11 distinct species. While C. braakii is part of the genome species 6 of the previous Citrobacter freundii complex, there is a lack of definitive research on the subject of Citrobacter bacteremia caused by lesser- known species. We report an unusual case of Citrobacter braakii bacteremia in a patient with multiple comorbidities that presented to the hospital with cellulitis and pleural effusion. Blood cultures grew Citrobacter braakii. Despite good response to antibiotic treatment, the patient's infection proved to be persistent and he succumbed to the cirrhosis of the liver and subsequent renal failure. Multiple and fatal underlying disease processes seem to worsen the likelihood of recovery from unusual infections. We believe our case report can add to the limited data available for C. braakii.

Selective and cytokine-dependent regulation of hepatic transporters and bile acid homeostasis during infectious colitis in mice.

Various disease models have been shown to alter hepatic drug-metabolizing enzyme (DME) and transporter expression and to induce cholestasis through altered enzyme and transporter expression. Previously, we detailed the regulation of hepatic DMEs during infectious colitis caused by Citrobacter rodentium infection. We hypothesized that this infection would also modulate hepatic drug transporter expression and key genes of bile acid (BA) synthesis and transport. Mice lacking Toll-like receptor 4 (TLR4), interleukin-6 (IL-6), or interferon-gamma (IFNγ) and appropriate wild-type animals were orally infected with C. rodentium and sacrificed 7 days later. In two wild-type strains, drug transporter mRNA expression was significantly decreased by infection for Slc22a4, Slco1a1, Slco1a4, Slco2b1, and Abcc6, whereas the downregulation of Abcc2, Abcc3, and Abcc4 were strain-dependent. In contrast, mRNA expressions of Slco3a1 and Abcb1b were increased in a strain-dependent manner. Expression of Abcb11, Slc10a1, the two major hepatic BA transporters, and Cyp7a1, the rate-limiting enzyme of BA synthesis, was also significantly decreased in infected animals. None of the above effects were caused by bacterial lipopolysaccharide, since they still occurred in the absence of functional TLR4. The downregulation of Slc22a4 and Cyp7a1 was absent in IFNγ-null mice, and the downregulation of Slco1a1 was abrogated in IL-6-null mice, indicating in vivo roles for these cytokines in transporter regulation. These data indicate that C. rodentium infection modulates hepatic drug processing through alteration of transporter expression as well as DMEs. Furthermore, this infection downregulates important genes of BA synthesis and transport and may increase the risk for cholestasis.

Citrobacter peritoneal dialysis peritonitis: rare occurrence with poor outcomes.

INTRODUCTION: Non-Pseudomonas gram-negative bacteria are responsible for an increasing proportion of cases of peritoneal dialysis (PD)-related peritonitis. The role of Citrobacter species in the etiology of PD-related peritonitis is often underestimated. In the present study, we aimed to describe the clinical features, laboratory findings, and short- and long-term outcomes in PD-related peritonitis caused by Citrobacter. METHODS: A retrospective review of all episodes of PD-related peritonitis caused by Citrobacter from a single center between 1990 and 2010 was performed. Clinical features, microbiological data, and outcomes of these episodes were analyzed. RESULTS: Citrobacter species was responsible for 11 PD-related episodes (1.8% of all peritonitis episodes) in 8 patients. Citrobacter freundii was the most common etiologic species (73%), and mixed growth was found in the other 3 episodes (27%). Approximately half (46%) of the episodes were associated with constipation and/or diarrhea. Of the Citrobacter isolates from all episodes, 54% were resistant to cefazolin, and only 18% were susceptible to cefmetazole. All isolates were susceptible to ceftazidime, cefepime, carbapenem, and aminoglycosides. More than half of the patients (54%) were hospitalized for index peritonitis, and 27% of the episodes involved a change in antibiotic medication. One patient had relapsing peritonitis caused by C. koseri (9%). The mortality rate of PD-related peritonitis caused by Citrobacter was 18%, and 89% of surviving patients developed technique failure requiring a modality switch after an average of 12 months of follow-up (range 1.2-31.2 months). CONCLUSION: PD-related peritonitis caused by Citrobacter is associated with poor outcomes, including high rates of antibiotic resistance, a high mortality rate, and a high rate of technique failure among survivors during the follow-up period.

[Effect of heavy metal salts on the growth and pathogenicity factors of opportunistic bacteria].

The paper presents experimental data on the effect of different concentrations of the salts of cadmium, copper, and zinc on the adaptive potentialities of the most common opportunistic microflora in the Volga-Caspian region. The findings suggest that natural microorganisms (Aeromonas and Citrobacter) show a high metal resistance that seems to be associated with steadily increased background levels of these metals in the waters of the Volga-Caspian basin.

[Persistense of mono- and associated cultures of conditionally pathogenic enterobacteria].

The comparative study of adhesive, hemolytic, DNA-ase, lecithinase, antilysozymic, anticomplementary activities of mono- and associated cultures of 57 Enterobacter spp., 61 Citrobacter spp. and 55 Serratia spp. strains, isolated from patients with pyoinflammatory, intestinal and urological diseases is carried out. Different variations of cocultivated bacteria including Enterobacter and Citrobacter, Enterobacter and Serratia, Citrobacter and Serratia are used. It was shown, that cocultivated Enterobacter, Citrobacter and Serratia bacteria increased the persistent properties of mixt cultures.

Identification and characterization of NleA, a non-LEE-encoded type III translocated virulence factor of enterohaemorrhagic Escherichia coli O157:H7.

Enterohaemorrhagic Escherichia coli (EHEC) O157:H7 uses a specialized protein translocation apparatus, the type III secretion system (TTSS), to deliver bacterial effector proteins into host cells. These effectors interfere with host cytoskeletal pathways and signalling cascades to facilitate bacterial survival and replication and promote disease. The genes encoding the TTSS and all known type III secreted effectors in EHEC are localized in a single pathogenicity island on the bacterial chromosome known as the locus for enterocyte effacement (LEE). In this study, we performed a proteomic analysis of proteins secreted by the LEE-encoded TTSS of EHEC. In addition to known LEE-encoded type III secreted proteins, such as EspA, EspB and Tir, a novel protein, NleA (non-LEE-encoded effector A), was identified. NleA is encoded in a prophage-associated pathogenicity island within the EHEC genome, distinct from the LEE. The LEE-encoded TTSS directs translocation of NleA into host cells, where it localizes to the Golgi apparatus. In a panel of strains examined by Southern blot and database analyses, nleA was found to be present in all other LEE-containing pathogens examined, including enteropathogenic E. coli and Citrobacter rodentium, and was absent from non-pathogenic strains of E. coli and non-LEE-containing pathogens. NleA was determined to play a key role in virulence of C. rodentium in a mouse infection model.

Yersiniabactin and other siderophores produced by clinical isolates of Enterobacter spp. and Citrobacter spp.

We analyzed the ability of extraintestinal strains of Enterobacter spp. and Citrobacter spp. to employ different siderophore-mediated strategies of iron acquisition. All strains produced iron-chelating compounds. Cross-feeding assays indicated that most isolates of both Enterobacter spp. and Citrobacter spp. excreted catecholate siderophore enterobactin, less produced aerobactin, and single strains excreted hydroxamates different from aerobactin. Besides, we analyzed if the strains had the ability to produce the siderophore yersiniabactin coded by the Yersinia high-pathogenicity island (HPI). The presence of HPI genes was observed in single isolates of three species: E. cloaceae, E. aerogenes and C. koseri. A detailed polymerase chain reaction analysis revealed differences in the genetic organization of the HPIs; however, in a cross-feeding test we proved that yersiniabactin was produced and the island was functional.

Citrobacter rodentium translocated intimin receptor (Tir) is an essential virulence factor needed for actin condensation, intestinal colonization and colonic hyperplasia in mice.

Citrobacter rodentium infection of mice serves as a relevant small animal model to study enterohaemorrhagic Escherichia coli (EHEC) and enteropathogenic E. coli (EPEC) infections in man. Enteropathogenic E. coli and EHEC translocate Tir into the host cytoplasmic membrane, where it serves as the receptor for the bacterial adhesin intimin and plays a central role in actin condensation beneath the adherent bacterium. In this report, we examined the function of C. rodentium Tir both in vitro and in vivo. Similar to EPEC, C. rodentium Tir is tyrosine phosphorylated and is essential for actin condensation. Citrobacter Tir and EPEC Tir are functionally interchangeable and both require tyrosine phosphorylation to mediate actin rearrangements. In contrast, Citrobacter Tir supports actin nucleation in EHEC independent of tyrosine phosphorylation, while EHEC Tir cannot replace Citrobacter Tir for this function. This indicates that C. rodentium and EPEC use an actin nucleating mechanism different from EHEC. We also found that Tir is expressed and translocated into mouse enterocytes in vivo by C. rodentium during infections. This represents the first direct demonstration of a type III effector translocated in vivo into a natural host by any pathogen. In addition, we showed that Tir, but not its tyrosine phosphorylation, is essential for C. rodentium to colonize the large bowel and induce attaching/effacing (A/E) lesions and colonic hyperplasia in mice, and that both EPEC Tir and EHEC Tir can substitute for Citrobacter Tir for these activities in vivo. These results thus demonstrate that Tir is an essential virulence factor in this infection model. The data also show that the function of Tir tyrosine phosphorylation and its subsequent actin nucleating activity are not essential for C. rodentium colonization of the mouse gut nor for inducing A/E lesions and colonic hyperplasia, thereby uncoupling colonization and disease from actin condensation for this A/E pathogen.

Low-virulence Citrobacter species encode resistance to multiple antimicrobials.

Citrobacter spp. are gram-negative commensal bacteria that infrequently cause serious nosocomial infections in compromised hosts. They are often resistant to cephalosporins due to overexpression of their chromosomal beta-lactamase. During a recent study of multidrug-resistant Enterobacteriaceae (MDRE) in solid-organ transplant patients, we found that almost half of patients colonized with MDRE carried one or more cefpodoxime-resistant Citrobacter freundii, Citrobacter braakii, or Citrobacter amalonaticus strains. Pulsed-field gel electrophoresis showed that 36 unique strains of Citrobacter were present among 32 patients. Genetic and phenotypic analysis of the resistance mechanisms of these bacteria showed that the extended-spectrum beta-lactamase (ESBL) SHV-5 or SHV-12 was encoded by 8 strains (26%) and expressed by 7 strains (19%). A number of strains were resistant to other drug classes, including aminoglycosides (28%), trimethoprim-sulfamethoxazole (31%), and fluoroquinolones (8%). PCR and DNA analysis of these multiresistant strains revealed the presence of class I integrons, including the first integrons reported for C. braakii and C. amalonaticus. The integrons encoded aminoglycoside resistance, trimethoprim resistance, or both. Despite the prevalence of MDR Citrobacter spp. in our solid-organ transplant patients, only a single infection with a colonizing strain was recorded over 18 months. Low-virulence Citrobacter spp., which can persist in the host for long periods, could influence pathogen evolution by accumulation of genes encoding resistance to multiple antimicrobial classes.

Long-Term outcome of neonatal Citrobacter koseri (diversus) meningitis treated with imipenem/meropenem and surgical drainage.

Neonatal Citrobacter koseri (diversus) meningitis is often complicated by the formation of brain abscesses and has a poor neurological outcome with seizures, mental retardation and paresis as sequelae in 50% of the cases. As there is emerging resistance to ampicillin, gentamicin and third-generation cephalosporins, we attempted to treat this infection with carbapenems. Carbapenems in combination with cefotaxime and surgical drainage may play an important role in treating C. koseri meningitis.

Secretion of cytokines by uroepithelial cells stimulated by Escherichia coli and Citrobacter spp.

Urinary tract epithelial cells (T 24/83) are able to express interleukin (IL)-6, IL-8, platelet-derived growth factor (PDGF) and tumour necrosis factor-alpha, but not IL-1 beta, IL-2, IL-4 and IL-10 in response to an infection with uropathogenic bacteria. The process of cytokine secretion is time dependent, with a significant increase in the cytokine activity after 60 min. The expression of virulence factors of the bacteria does not seem to play a role. The interaction between bacterial products (e.g. lipopolysaccharide) and/or bacterial adhesion mediated by adhesins and specific receptor molecules of cell surfaces may be responsible for the activity of mediator protein expression in the epithelial cells. The release of PDGF and IL-8 was found to be higher when due to Escherichia coli HB 101 (rough form) than that caused by other bacterial strains. Citrobacter CB 3009 provoked the highest level of IL-6. The PDGF level correlated significantly with IL-6 and IL-8 values (P<0.001). There was a significant correlation between the time-dependent release of IL-6 and IL-8 (P<0.05). In epithelial cytokine response to bacterial infection, the reaction of the epithelial cells may modify themselves (e.g. internalization of bacteria) and the immuno-regulatory processes that are caused by infection and responsible for parenchymal injury.