Evidence of cross-contamination of waste workers and transmission of antimicrobial resistance genes by coagulase-negative Staphylococcus isolated from dental solid waste: an intriguing study.

The aim of this study was to phenotypically and genotypically identify coagulase-negative Staphylococcus (CoNS) recovered from the nostrils of waste workers and from dental waste; 135 strains were recovered and S. epidermidis was the prevailing species. Genetic similarity (100%) was observed between the two S. epidermidis isolated from different employees on the same shift and 85% similarity between the S. epidermidis recovered from an employee's nostril and from waste. The mecA gene was found in 20 CoNS, and 20% were also found to possess the vanA gene. The blaZ gene was detected in 46.7%, and the icaA (34.8%), B and C genes (11.8% each). Our findings emphasized the biological risk to which waste workers are exposed and unprecedently confirms that it was possible to recover genetically identical bacterial species from waste and from workers' nostrils. It is important to highlight that this risk is raised by the detection of relevant antimicrobial resistance genes. The results also suggest that effective measures to correctly manage waste and promote the rational use of antimicrobials should be adopted.

Rapid detection of the New Delhi metallo-b-lactamase 1 (NDM-1) gene by loop-mediated isothermal amplification (LAMP).

BACKGROUND: New Delhi Metallo-b-lactamase (NDM-1) is an enzyme emerging around the world conferring resistance to a wide range of ß-lactams agents and whose early detection is extremely important. We proposed to standardize the detection of the blaNDM-1 gene using the LOOP-mediated isothermal amplification technique (LAMP). METHODS: In all, 14 Gram-negative bacterial strains isolated from patients presenting pneumonia associated with mechanical ventilation were used for the blaNDM-1 standardization by LAMP. Klebsiella pneumoniae ATCC BAA-2473 and two clinical strains were used as a positive control. All results were compared to the reaction in polymerase chain reaction (PCR), considered gold standard for this detection. RESULTS: There was an excellent correlation between the two techniques employed, since all measured clinical strains were negative in both employed tests and two clinical, and a reference strains were positive. CONCLUSIONS: The lamp technique seems to be an excellent option for the rapid detection of blaNDM-1. The amplification time is much shorter than other molecular techniques, the PCR machine is not necessary, it is easy of implementation and costs is low.

Knowledge, behaviour and microbial load of workers handling dental solid waste in a public health service in Brazil.

Healthcare wastes are those generated inside healthcare services, including dental clinics. Workers coming into close proximity to hazardous healthcare waste are potentially at risk. In an attempt to assess the knowledge and attitudes of workers dealing with infectious waste, a questionnaire was administered. The biological risk was investigated by evaluating the microbial load and screening some clinically relevant micro-organisms in the nasal mucosa, hands and coats of these workers. The results showed that 66.6% of the study population had incomplete primary education. Only two workers have had their blood tested to confirm anti-HBs levels. Microbial load evaluation on hand surfaces of morning workers showed statistically significant lower microbial loads after the workday when compared with the beginning of the work period. It is important to highlight that some clinically relevant bacteria, such as Pseudomonas aeruginosa and Klebsiella pneumoniae were isolated from worker's hands. This study revealed the need for more training programmes regarding awareness of safe waste disposal protocols and also the necessity of discussing vaccination and its implications. Data regarding microbial loads of the worker's hands, mostly at the beginning of the workday when handwashing is recommended worldwide, emphasise that hygiene measures should receive more attention during training exercises.

Phenotypic and molecular detection of the bla KPC gene in clinical isolates from inpatients at hospitals in São Luis, MA, Brazil.

BACKGROUND: Bacteria that produce Klebsiella pneumoniae carbapenemases (KPCs) are resistant to broad-spectrum ß-lactam antibiotics. The objective of this study was to phenotypically and genotypically characterize the antibiotic susceptibility to carbapenems of 297 isolates recovered from clinical samples obtained from inpatients at 16 hospitals in São Luis (Maranhão, Brazil). METHODS: The study was conducted using phenotypic tests and molecular methods, including polymerase chain reaction (PCR), sequencing and enterobacterial repetitive intergenic consensus (ERIC)-PCR. The nonparametric chi-square test of independence was used to evaluate the associations between the bacterial bla KPC gene and the modified Hodge test, and the chi-square adherence test was used to assess the frequency of carbapenemases and their association with the bla KPC gene. RESULTS: The most frequently isolated species were Acinetobacter baumannii (n = 128; 43.0%), K. pneumoniae (n = 75; 25.2%), and Pseudomonas aeruginosa (n = 42; 14.1%). Susceptibility assays showed that polymixin B was active against 89.3% of the bacterial isolates. The Acinetobacter spp. and K. pneumoniae strains were susceptible to amikacin and tigecycline, and Pseudomonas spp. were sensitive to gentamicin and amikacin. Among the 297 isolates, 100 (33.7%) were positive for the bla KPC gene, including non-fermentative bacteria (A. baumannii) and Enterobacteriaceae species. Among the isolates positive for the bla KPC gene, K. pneumoniae isolates had the highest positivity rate of 60.0%. The bla KPC gene variants detected included KPC-2, which was found in all isolates belonging to species of the Enterobacteriaceae family. KPC-2 and KPC-3 were observed in A. baumannii isolates. Importantly, the bla KPC gene was also detected in three Raoultella isolates and one isolate of the Pantoea genus. ERIC-PCR patterns showed a high level of genetic diversity among the bacterial isolates; it was capable of distinguishing 34 clones among 100 strains that were positive for bla KPC and were circulating in 11 of the surveyed hospitals. CONCLUSIONS: The high frequency of the bla KPC gene and the high degree of clonal diversity among microorganisms isolated from patients from different hospitals in São Luis suggest the need to improve the quality of health care to reduce the incidence of infections and the emergence of carbapenem resistance in these bacteria as well as other Gram-negative pathogens.

Isolation and identification of Candida species in patients with orogastric cancer: susceptibility to antifungal drugs, attributes of virulence in vitro and immune response phenotype.

BACKGROUND: Because of the inherent immunosuppression of cancer patients opportunistic infections by Candida spp, occur frequently. This study aimed to identify Candida species in the oral mucosa of 59 patients with orogastric cancer (OGC) and to analyze the immunological phenotype of these patients. METHODS: The yeasts were identified by MALDI-TOF mass spectrometry (MS). For all isolates, we performed phospholipases and proteinases assays, in vitro adherence to buccal epithelial cells (BEC), minimum inhibitory concentration of antifungal drugs and determined the cytokine profile by Cytometric Bead Array flow citometry assay. RESULTS: C. albicans was the most prevalent species in OGC patients (51.6 %) and control group (66.7 %). Candida spp. strains isolated from OGC patients exhibited better adherence to BEC (p = 0.05) than did the control group. Phospholipases production by Candida strains from OGC patients was lower (51.6 %) than in the control group (61.9 %). Proteinases were detected in 41.9 % and 4.8 % of the yeasts from OGC patients and control group, respectively. Significant differences were found in the serum of OGC patients compared to the control group for IL-2, IL-10, TNF-α, IFN-γ and IL-17. CONCLUSIONS: The results of this work suggest increased virulence of yeasts isolated from OGC patients and, that this may interfere with the immune phenotype.

Solid Lipid Nanoparticles Loaded with Retinoic Acid and Lauric Acid as an Alternative for Topical Treatment of Acne Vulgaris.

Topical therapy is the first choice for the treatment of mild to moderate acne and all-trans retinoic acid is one of the most used drugs. The combination of retinoids and antimicrobials is an innovative approach for acne therapy. Recently, lauric acid, a saturated fatty acid, has shown strong antimicrobial activity against Propionibacterium acnes. However, topical application of retinoic acid is followed by high incidence of side-effects, including erythema and irritation. Solid lipid nanoparticles represent an alternative to overcome these side-effects. This work aims to develop solid lipid nanoparticles loaded with retinoic acid and lauric acid and evaluate their antibacterial activity. The influence of lipophilic stearylamine on the characteristics of solid lipid nanoparticles was investigated. Solid lipid nanoparticles were characterized for size, zeta potential, encapsulation efficiency, differential scanning calorimetry and X-ray diffraction. The in vitro inhibitory activity of retinoic acid-lauric acid-loaded solid lipid nanoparticles was evaluated against Propionibacterium acnes, Staphylococcus aureus and Staphylococcus epidermidis. High encapsulation efficiency was obtained at initial time (94 ± 7% and 100 ± 4% for retinoic acid and lauric acid, respectively) and it was demonstrated that lauric acid-loaded-solid lipid nanoparticles provided the incorporation of retinoic acid. However, the presence of stearylamine is necessary to ensure stability of encapsulation. Moreover, retinoic acid-lauric acid-loaded solid lipid nanoparticles showed growth inhibitory activity against Staphylococcus epidermidis, Propionibacterium acnes and Staphylococcus aureus, representing an interesting alternative for the topical therapy of acne vulgaris.

Phenotypic and genotypic diversity of multidrug-resistant Pseudomonas aeruginosa Isolates from bloodstream infections recovered in the Hospitals of Belo Horizonte, Brazil.

BACKGROUND: Pseudomonas aeruginosa commonly causes nosocomial bloodstream infections and the emergence of a variety of ß-lactamases (BLs) is worrying. In 5 hospitals in Belo Horizonte, Brazil, the presence of phenotypes encoding BL genes was established and the genetic diversity of the P. aeruginosa strains recovered from bloodstream infections was analyzed. MATERIALS AND METHODS: The isolates were investigated using a disk diffusion (DD) method and the Etest, for encoding metallo-ß-lactamases (MBLs), oxacillinases and cephalosporinases. Genes and genetic diversity were evaluated by random amplified polymorphic DNA (RAPD) genotyping and enterobacterial repetitive intergenic consensus (ERIC)-PCR. RESULTS: Twelve strains (30%) were positive for MBLs by Etest and DD, 15 were cephalosporinase-positive and 87.5% were positive for blaSPM-1 and blaVIM-1. Twenty-three strains (57.5%) were grouped into profile A, 32.5% into profile B and 10% into profile C by RAPD genotyping. ERIC-PCR revealed a varying degree of similarity between strains, ranging from 45 to 100%. CONCLUSIONS: The results suggest distinct clonal populations in the 5 hospitals studied, indicating a potentially problematic epidemiological situation in Belo Horizonte, Brazil.

Proteomic changes in Bacteroides fragilis exposed to subinhibitory concentration of piperacillin/tazobactam.

Bacteroides fragilis is the anaerobe most frequently isolated from clinical specimens and piperacillin/tazobactam is among the drugs that can be used to treat polymicrobial infections in which this bacteria is often involved. During antibiotic therapy, inhibitory concentrations of antibiotics are always followed by subinhibitory concentrations which can generate phenotypic changes in bacteria. So, in this study we aimed to evaluate changes in the proteomic profile of B. fragilis grown in a sub-MIC of PTZ, using 2-D electrophoresis followed by matrix-assisted laser desorption/ionization time-of-flight/time of-flight. Analysis of the 2-DE gels showed 18 spots with significantly different volume percentages between experimental conditions and 12 were successfully identified by MS/MS. Two proteins with decreased abundance in sub-MIC condition were involved in the glycolysis (glyceraldehyde-3-phosphate dehydrogenase and triose phosphate isomerase), others two involved in amino acid metabolism (Oxoacyl-(acyl-carrier protein) synthase II and dihydrodipicolinate reductase), and finally, one protein involved in fatty acid metabolism (UDP-N-acetylglucosamine acyltransferase). Among the proteins with increased abundance, we founded three ATP synthase (alpha, beta, and alpha type V), which could be involved in antibiotic bacterial resistance by efflux pump, one protein involved in glycolysis (enolase), and one involved in protein degradation (aminoacyl-histidine dipeptidase). In conclusion, our data show overall changes in the proteome of B. fragilis conducted by sub-MIC of PTZ, whose consequences on bacterial physiology deserve further investigation.

Impact of the contamination time by Escherichia coli on biofilm formation in surgical instruments.

OBJECTIVES: to evaluate the microbial load and adherence of Escherichia coli in different areas of the surgical instrument surface exposed to experimental contamination over time. METHODS: experimental study in which fragments of crile forceps (serrated, rod and rack) were contaminated by immersion in Tryptic Soy Broth, containing 106 CFU/mL of E. coli, for 1, 2, 4, 6, 8, 12 and 24 hours. Microbial load and bacterial adherence were evaluated using microbiological culture and scanning electron microscopy, respectively. RESULTS: there was an increase in the microbial load on the surgical instrument, proportional to the contamination interval, ranging from 102 after 1 hour to 105 CFU/cm2 in 24 hours. The presence of exopolysaccharide was detected after two hours of contamination. CONCLUSIONS: microbial load and adhesion of E. coli increased over time, reaching 105 CFU/cm2 after 24 hours of contamination, starting biofilm formation after two hours.

Effectiveness of manual versus automated cleaning on Staphylococcus epidermidis biofilm removal from the surface of surgical instruments.

BACKGROUND: Biofilm removal is a challenge during surgical instrument processing. We analyzed the time required for Staphylococcus epidermidis to form biofilms on surgical instruments, and how cleaning methods removed them. METHODS: Different areas (ratchet, shank, and jaw) of straight crile forceps were contaminated by soaking in Tryptic Soy Broth containing 106 colony forming units (CFU)/mL of S epidermidis for 1, 2, 4, 6, 8, and 12 hours. S epidermidis adhesion and removal, after manual or automated ultrasonic cleaning, was evaluated by microbiological culture and scanning electron microscopy. RESULTS: Microbial load increased with time (101-102 CFU/cm2 after 1 hour; 104 CFU/cm2 after 12 hours). Exopolysaccharide was detected after 2 hours and gradually increased thereafter. Bacterial load was reduced by 1-2 log10 after manual cleaning and 1-3 log10 after automated cleaning, but biofilms were not completely eliminated. In general, bacterial load was lower in shank fragments. This difference was significant at 6 hours. CONCLUSIONS: Rapid adhesion of S epidermidis and exopolysaccharide formation was observed on surgical instruments. Automated cleaning was more effective than manual cleaning, but neither method removed biofilms completely. The precleaning conditions and the forceps design are critical factors in processing quality.

Exploring the Potential of CRISPR-Cas9 Under Challenging Conditions: Facing High-Copy Plasmids and Counteracting Beta-Lactam Resistance in Clinical Strains of Enterobacteriaceae.

The antimicrobial resistance (AMR) crisis urgently requires countermeasures for reducing the dissemination of plasmid-borne resistance genes. Of particular concern are opportunistic pathogens of Enterobacteriaceae. One innovative approach is the CRISPR-Cas9 system which has recently been used for plasmid curing in defined strains of Escherichia coli. Here we exploited this system further under challenging conditions: by targeting the bla TEM- 1 AMR gene located on a high-copy plasmid (i.e., 100-300 copies/cell) and by directly tackling bla TEM- 1-positive clinical isolates. Upon CRISPR-Cas9 insertion into a model strain of E. coli harboring bla TEM- 1 on the plasmid pSB1A2, the plasmid number and, accordingly, the bla TEM- 1 gene expression decreased but did not become extinct in a subpopulation of CRISPR-Cas9 treated bacteria. Sequence alterations in bla TEM- 1 were observed, likely resulting in a dysfunction of the gene product. As a consequence, a full reversal to an antibiotic sensitive phenotype was achieved, despite plasmid maintenance. In a clinical isolate of E. coli, plasmid clearance and simultaneous re-sensitization to five beta-lactams was possible. Reusability of antibiotics could be confirmed by rescuing larvae of Galleria mellonella infected with CRISPR-Cas9-treated E. coli, as opposed to infection with the unmodified clinical isolate. The drug sensitivity levels could also be increased in a clinical isolate of Enterobacter hormaechei and to a lesser extent in Klebsiella variicola, both of which harbored additional resistance genes affecting beta-lactams. The data show that targeting drug resistance genes is encouraging even when facing high-copy plasmids. In clinical isolates, the simultaneous interference with multiple genes mediating overlapping drug resistance might be the clue for successful phenotype reversal.

Composition analysis of dental solid waste in Brazil.

When developing proper waste management strategies, it is essential to characterize the volume and composition of solid waste. The aim of this work was to evaluate the composition of dental waste produced by three dental health services in Belo Horizonte, Minas Gerais State, Brazil. Two universities, one public and one private, and one public dental health service were selected. Waste collection took place from March to November 2007. During this period, three samples were collected from each dental health service. The total amount of dental waste produced in one day of dental work was manually separated into three categories: infectious and potentially infectious waste, accounting for 24.3% of the total waste; non-infectious waste, accounting for 48.1%; and domestic-type waste, accounting for 27.6% (percentages are for mean weights of solid waste). Our results showed that most of the waste considered as biomedical may be misclassified, consequently making the infectious waste amount appear much larger. In addition, our results suggest that the best waste minimization method is recycling, and they help to define an appropriate waste management system in all three of the dental health services involved in this study.

Investigating cross-contamination by yeast strains from dental solid waste to waste-handling workers by DNA sequencing.

Trying to widen the discussion on the risks associated with dental waste, this study proposed to investigate and genetically compare yeast isolates recovered from dental solid waste and waste workers. Three samples were collected from workers' hands, nasal mucosa, and professional clothing (days 0, 30, and 180), and two from dental waste (days 0 and 180). Slide culture, microscopy, antifungal drug susceptibility, intersimple sequence repeat analysis, and amplification and sequencing of internal transcribed spacer regions were performed. Yeast strains were recovered from all waste workers' sites, including professional clothes, and from waste. Antifungal susceptibility testing demonstrated that some yeast recovered from employees and waste exhibited nonsusceptible profiles. The dendrogram demonstrated the presence of three major clusters based on similarity matrix and UPGMA grouping method. Two branches displayed 100% similarity: three strains of Candida guilliermondii isolated from different employees, working in opposite work shifts, and from diverse sites grouped in one part of branch 1 and cluster 3 that included two samples of Candida albicans recovered from waste and the hand of one waste worker. The results suggested the possibility of cross-contamination from dental waste to waste workers and reinforce the need of training programs focused on better waste management routines.

Impact of the contamination time by Escherichia coli on biofilm formation in surgical instruments / Impacto del tiempo de contaminación por Escherichia coli en la formación de biofilm en instrumentos quirúrgicos / Impacto do tempo de contaminação por Escherichia coli na formação de biofilme em instrumentos cirúrgicos

ABSTRACT Objectives: to evaluate the microbial load and adherence of Escherichia coli in different areas of the surgical instrument surface exposed to experimental contamination over time. Methods: experimental study in which fragments of crile forceps (serrated, rod and rack) were contaminated by immersion in Tryptic Soy Broth, containing 106 CFU/mL of E. coli, for 1, 2, 4, 6, 8, 12 and 24 hours. Microbial load and bacterial adherence were evaluated using microbiological culture and scanning electron microscopy, respectively. Results: there was an increase in the microbial load on the surgical instrument, proportional to the contamination interval, ranging from 102 after 1 hour to 105 CFU/cm2 in 24 hours. The presence of exopolysaccharide was detected after two hours of contamination. Conclusions: microbial load and adhesion of E. coli increased over time, reaching 105 CFU/cm2 after 24 hours of contamination, starting biofilm formation after two hours.

RESUMEN Objetivos: evaluar la carga microbiana y adherencia de Escherichia coli en diferentes áreas de la superficie de instrumento quirúrgico expuesto a la contaminación experimental a lo largo del tiempo. Métodos: estudio experimental en que fragmentos de tenacillas quirúrgicas (sierra, asta y cremallera), contaminados por inmersión en Tryptic Soy Broth, conteniendo 106 UFC/mL de E. coli, por 1, 2, 4, 6, 8, 12 y 24 horas. La carga microbiana y la adherencia bacteriana evaluadas con uso de cultivo y microscopia electrónica de barredura, respectivamente Resultados: verificó aumento de la carga microbiana en el instrumento quirúrgico, proporcional al intervalo de contaminación, variando de 102 tras 1 hora a 105 UFC/cm2 en 24 horas. La presencia de polisacárido detectada tras 2 horas de contaminación. Conclusiones: carga microbiana y adherencia de E. coli aumentaron a lo largo del tiempo, atingiendo 105 UFC/cm2 tras 24 horas de contaminación, iniciándose formación de biopelícula tras 2 horas.

RESUMO Objetivos: avaliar a carga microbiana e a aderência de Escherichia coli em diferentes áreas da superfície de instrumento cirúrgico exposto à contaminação experimental ao longo do tempo. Métodos: estudo experimental em que fragmentos de pinças crile (serrilha, haste e cremalheira) foram contaminados por imersão em Tryptic Soy Broth, contendo 106 UFC/mL de E. coli, por 1, 2, 4, 6, 8, 12 e 24 horas. A carga microbiana e a aderência bacteriana foram avaliadas com uso de cultura microbiológica e microscopia eletrônica de varredura, respectivamente. Resultados: verificou-se aumento da carga microbiana no instrumento cirúrgico, proporcional ao intervalo de contaminação, variando de 102 após 1 hora a 105 UFC/cm2 em 24 horas. A presença de exapolissacarídeo foi detectada após 2 horas de contaminação. Conclusões: carga microbiana e aderência de E. coli aumentaram ao longo do tempo, atingindo 105 UFC/cm2 após 24 horas de contaminação, iniciandose formação de biofilme após 2 horas.

Analysis of microbial load on surgical instruments after clinical use and following manual and automated cleaning.

BACKGROUND: We aimed to monitor the microbial load and identify the microorganisms recovered from surgical instruments after clinical use and following manual and automated cleaning. METHODS: This experimental study was carried out in the Laboratory of Oral Microbiology and Anaerobes at the Federal University of Minas Gerais in Brazil. Microbial samples were taken from 125 surgical instruments used in 25 types of gastrointestinal surgeries. RESULTS: The average microbial load was 93.1 CFU/100 mL after clinical use and 41 CFU/100 mL and 8.24 CFU/100 mL on instruments following 2 sequential steps of manual cleaning, respectively, and 75 CFU/100 mL and 16.1 CFU/100 mL on instruments after automated cleaning. Surgical wound classification significantly affected the microbial load recovered on instruments. Coagulase-negative Staphylococcus, Escherichia coli, Pseudomonas spp, Stenotrophomonas maltophilia, and Acinetobacter baumannii complex were recovered. CONCLUSIONS: The average microbial load observed after the cleaning steps decreased, and the decrease in microbial load was more pronounced using the manual method compared with that observed using the automated method.

Antimicrobial susceptibility of microorganisms recovered from intraabdominal infections at Belo Horizonte, Brazil.

We evaluated antimicrobial susceptibility patterns of microorganisms isolated from intraabdominal infection of Brazilian patients, by agar dilution, agar diffusion, and E test. Among the strictly anaerobes, 57.7% were resistant to penicillin, 28.2% to clindamycin, and 9.9% to metronidazole. The majority of Escherichia coli and Staphylococcus were sensitive and resistant to almost all drugs, respectively. Half of Candida samples were resistant to itraconazole. Our data reinforce the importance of this kind of study to support rational antimicrobial therapy.

Count, identification and antimicrobial susceptibility of bacteria recovered from dental solid waste in Brazil.

In Brazil, few studies on microbial content of dental solid waste and its antibiotic susceptibility are available. An effort has been made through this study to evaluate the hazardous status of dental solid waste, keeping in mind its possible role in cross-infection chain. Six samples of solid waste were collected at different times and seasons from three dental health services. The microbial content was evaluated in different culture media and atmospheric conditions, and the isolates were submitted to antibiotic susceptibility testing. A total of 766 bacterial strains were isolated and identified during the study period. Gram-positive cocci were the most frequent morphotype isolated (48.0%), followed by Gram-negative rods (46.2%), Gram-positive rods (5.0%), Gram-negative-cocci (0.4%), and Gram-positive coccobacillus (0.1%). Only two anaerobic bacteria were isolated (0.3%). The most frequently isolated species was Staphylococcus epidermidis (29.9%), followed by Stenotrophomonas maltophilia (8.2%), and Enterococcus faecalis (6.7%). High resistance rate to ampicillin was observed among Gram-negative rods (59.4%) and Gram-positive cocci (44.4%). For Gram-negative rods, high resistance was also noted to aztreonam (47.7%), cefotaxime (47.4%), ceftriaxone and cefazolin (43.7%), and ticarcillin-clavulanic acid (38.2%). Against Gram-positive cocci penicillin exhibit a higher resistance rate (45.0%), followed by ampicillin, erythromycin (27.2%), and tetracycline (22.0%). The present study demonstrated that several pathogenic bacteria are present in dental solid waste and can survive after 48 h from the waste generation time and harbor resistance profiles against several clinical recommended antibiotics.

Alteration in the endogenous intestinal flora of Swiss Webster mice by experimental Angiostrongylus costaricensis infection.

The association between worm infections and bacterial diseases has only recently been emphasized. This study examined the effect of experimental Angiostrongylus costaricensis infection on endogenous intestinal flora of Swiss Webster mice. Eight mice aging six weeks were selected for this experiment. Four were infected with A. costaricensis and the other four were used as controls. Twenty eight days after the worm infection, all mice in both groups were sacrificed and samples of the contents of the ileum and colon were obtained and cultured for aerobic and anaerobic bacteria. In the mice infected with A. costaricensis there was a significant increase in the number of bacteria of the endogenous intestinal flora, accompanied by a decrease in the number of Peptostreptococcus spp. This alteration in the intestinal flora of mice infected by the nematode may help to understand some bacterial infections described in humans.

Alteration in the endogenous intestinal flora of swiss webster mice by experimental Angiostrongylus costaricensis infection

The association between worm infections and bacterial diseases has only recently been emphasized. This study examined the effect of experimental Angiostrongylus costaricensis infection on endogenous intestinal flora of Swiss Webster mice. Eight mice aging six weeks were selected for this experiment. Four were infected with A. costaricensis and the other four were used as controls. Twenty eight days after the worm infection, all mice in both groups were sacrificed and samples of the contents of the ileum and colon were obtained and cultured for aerobic and anaerobic bacteria. In the mice infected with A. costaricensis there was a significant increase in the number of bacteria of the endogenous intestinal flora, accompanied by a decrease in the number of Peptostreptococcus spp. This alteration in the intestinal flora of mice infected by the nematode may help to understand some bacterial infections described in humans.