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PubMed2002

Comparative phenotypic, molecular, and virulence characterization of Vibrio parahaemolyticus O3:K6 isolates.

Historically, Vibrio parahaemolyticus infections have been characterized by sporadic cases caused by multiple, diverse serotypes. However, since 1996, V. parahaemolyticus serotype O3:K6 strains have been associated with several large-scale outbreaks of illness, suggesting the emergence of a "new" group of organisms with enhanced virulence. We have applied three different molecular subtyping techniques to identify an appropriate method for differentiating O3:K6 isolates from other serotypes. Pulsed-field gel electrophoresis (PFGE) following NotI digestion differentiated seven closely related subtypes among O3:K6 and related strains, which were distinct from PFGE patterns for non-O3:K6 isolates. Ribotyping and tdh sequencing were less discriminatory than PFGE, but further confirmed close genetic relationships among recent O3:K6 isolates. In vitro adherence and cytotoxicity studies with human epithelial cells showed that O3:K6 isolates exhibited statistically higher levels of adherence and cytotoxicity to host cells than non-O3:K6 isolates. Epithelial cell cytotoxicity patterns were determined with a lactate dehydrogenase release assay. At 3 h postinfection, high relative cytotoxicities (>50% maximum lactate dehydrogenase activity) were found among a greater proportion of recently isolated O3:K6 and closely related strains (75%) than among the non-O3:K6 isolates (23%). A statistically significant relationship between adherence and cytotoxicity suggests that the pathogenic potential of some isolates may be associated with increased adherence to epithelial cells. Our findings suggest that enhanced adherence and cytotoxicity may contribute to the apparent unique pathogenic potential of V. parahaemolyticus O3:K6 strains.

Bacterial Adhesion↗
PubMed1977

Experience with a microscopic screening program for sputum specimens.

Microscopic examination of almost 2,000 sputum specimens was performed over a 3 1/2-month period. The specimens were categorized into 6 groups based on numbers of leukocytes (PMN's) and squamous epithelial cells (SEC's) observed at low magnification (X 100). Bacteriologic evaluation of specimens consisted of identification and antimicrobial susceptibility tests of potential pathogens when growth was equal or predominant to the growth of oropharyngeal flora. Specimens containing greater than 25 PMN's and less than 25 SEC's had potential pathogens identified in 51% of the samples. Specimen containing greater than 25 SEC's and any number of PMN's showed a rate on only 19%. Specimens containing less than 25 PMN's and SEC's had a rate of 13%. Since initiating the screening program in which sputum specimens containing greater than 25 SEC's were unacceptable for culture, the per cent of acceptable specimens received by the laboratory nearly doubled.

Bacteria↗
PubMed1989

Xanthomonas maltophilia: an emerging nosocomial pathogen.

Xanthomonas maltophilia is a potentially pathogenic organism with a broad clinical spectrum. Nosocomial colonization and infection are the most common manifestations. The incidence of clinical isolation of X. maltophilia is on the rise, possibly in part because of the selective pressure from the new antimicrobial agents to which it is resistant. The organism is usually resistant to commonly used antimicrobial agents, including most cephalosporins, aztreonam, antipseudomonal penicillins, imipenem, and the quinolones.

Bacterial Infections↗
PubMed2001

Pathogenic determinants of the mucosally transmissible CXCR4-specific SHIV(SF33A2) map to env region.

Infection of rhesus macaques with chimeric simian-human immunodeficiency viruses (SHIV) is an established method to study AIDS pathogenesis and is increasingly used to assess the efficacy of vaccine and antiviral candidates. For these reasons, a detailed understanding of those molecular determinants, which confer pathogenic potential to SHIV viruses, should assist in both rational experimental design and interpretation of results. In this report, we describe the development and in vivo characterization of a pathogenic molecular clone, SHIVSF33A2, which contains an envelope sequence derived from the CXCR4-dependent isolate, HIV-1SF33. Proviral DNA, amplified from a rhesus macaque infected with the pathogenic isolate SHIVSF33A, was substituted into the corresponding region of the parental, nonpathogenic SHIVSF33 genome creating the molecular clone SHIVSF33A2. Coreceptor specificity of SHIVSF33A2 was determined to be CXCR4 specific. Naive rhesus macaques were productively infected after a single exposure to cell-free SHIVSF33A2 by either the intravenous (IV) or intravaginal (IVAG) routes. Animals infected with SHIVSF33A2 suffered a severe loss of peripheral CD4+ T cells and high acute plasma viremia with development of simian AIDS 9 months after inoculation. Sequence analysis identified 25 discreet amino acid changes within the V1-V5 regions of the envelope protein when compared with the nonpathogenic parental virus. These data indicate that domains within the HIV-1 envelope protein are sufficient to define pathogenic potential in the context of the SIVmac239 genome.

Amino Acid Sequence↗
PubMed2006

Detection of Escherichia coli O157:H7, Salmonella spp., Staphylococcus aureus and Listeria monocytogenes in kimchi by multiplex polymerase chain reaction (mPCR).

We developed an mPCR assay for the simultaneous detection, in one tube, of Escherichia coli O157:H7, Salmonella spp., Staphylococcus aureus and Listeria monocytogenes using species-specific primers. The mPCR employed the E. coli O157:H7 specific primer Stx2A, Salmonella spp. specific primer Its, S. aureus specific primer Cap8A-B and L. monocytogenes specific primer Hly. Amplification with these primers produced products of 553, 312, 405 and 210 bp, respectively. All PCR products were easily detected by agarose gel electrophoresis, and the sequences of the specific amplicons assessed. Potential pathogenic bacteria, in laboratory-prepared and four commercially available kimchi products, were using this mPCR assay, and the amplicons cloned and sequenced. The results correlated exactly with sequences derived for amplicons obtained during preliminry tests with known organisms. The sensitivity of the assay was determined for the purified pathogen DNAs from four strains. The mPCR detected pathogen DNA at concentrations ranging from approximately 0.45 to 0.05 pM/microl. Thus, this mPCR assay may allow for the rapid, reliable and cost-effective identification of four potentially pathogens present in the mixed bacterial communities of commercially available kimchi.

DNA Primers↗
PubMed1988

Clinical significance of aerobic bacterial flora of the uterus, vagina, vestibule, and clitoral fossa of clinically normal mares.

Swab specimens for bacterial culture were obtained from the uterus, vagina, vestibule, and clitoral fossa of 48 mares that had normal reproductive tracts, no history of reproductive problems, and no inflammation on evaluation of endometrial biopsy. The mares were predominantly Thoroughbred and Standardbred. Swab specimens of the vagina were obtained through a sterile speculum; swab specimens of the uterus were obtained by use of a double-guarded, occluded culture instrument. Fifteen (31%) of the uterine swab specimens and 20 (42%) of the vaginal swab specimens yielded growth on aerobic culture; however, only 2 (4%) of the uterine swab specimens and 4 (8%) of the vaginal swab specimens yielded growth of more than 10 colonies. In contrast, 21 (44%) of the vestibular swab specimens and 45 (94%) of the clitoral fossa swab specimens had moderate (greater than 10 colonies in 1 quadrant) to heavy (colonies in 2 or 3 quadrants) growth of organisms on culture. Of organisms considered to be potential pathogens, Streptococcus zooepidemicus and Escherichia coli were found on bacteriologic culture of several clitoral fossa swab specimens and of some vestibular swab specimens. We did not isolate any potential pathogens from uterine or vaginal swab specimens. It appears that 1 to 10 colonies of nonpathogenic organisms could be recovered from the uterus in a substantial number of clinically normal mares even when double-guarded swabbing techniques are used, and we suggest that prebreeding culture requirements be modified to reflect this. Also, our findings indicate that the vulvovaginal fold, rather than the cervix, might be the major barrier to ascending bacterial contamination of the reproductive tract.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1982

[Longitudinal studies into alterations of vaginal flora during pregnancy on the basis of modern perinatal medicine (author's transl)].

Assessment of the uterine cervix score is a valuable method for early diagnosis of imminent premature birth, particularly in the context of high-risk pregnancy. Cervical insufficiency was recorded from 14 per cent of a high-risk group of patients. Longitudinal studies covered 110 probands with high-risk pregnancy and repeated vaginal examinations and 45 pregnant women with no vaginal examinations. No significant difference was found to exist between the two groups regarding percentual occurrence of potentially pathogenic aerobic germs, up to the 38th week of pregnancy. Highly significant decline in germ incidence was longitudinally recordable from both groups during the period of amnioscopy. Exposure to potentially pathogenic germs was not aggravated by repeated vaginal checks during pregnancy. Additional conclusions are drawn for practice.

Amniotic Fluid↗
PubMed2004

Infection control in cystic fibrosis.

Over the past 20 years there has been a greater interest in infection control in cystic fibrosis (CF) as patient-to-patient transmission of pathogens has been increasingly demonstrated in this unique patient population. The CF Foundation sponsored a consensus conference to craft recommendations for infection control practices for CF care providers. This review provides a summary of the literature addressing infection control in CF. Burkholderia cepacia complex, Pseudomonas aeruginosa, and Staphylococcus aureus have all been shown to spread between patients with CF. Standard precautions, transmission-based precautions including contact and droplet precautions, appropriate hand hygiene for health care workers, patients, and their families, and care of respiratory tract equipment to prevent the transmission of infectious agents serve as the foundations of infection control and prevent the acquisition of potential pathogens by patients with CF. The respiratory secretions of all CF patients potentially harbor clinically and epidemiologically important microorganisms, even if they have not yet been detected in cultures from the respiratory tract. CF patients should be educated to contain their secretions and maintain a distance of >3 ft from other CF patients to avoid the transmission of potential pathogens, even if culture results are unavailable or negative. To prevent the acquisition of pathogens from respiratory therapy equipment used in health care settings as well as in the home, such equipment should be cleaned and disinfected. It will be critical to measure the dissemination, implementation, and potential impact of these guidelines to monitor changes in practice and reduction in infections.

Cystic Fibrosis↗
PubMed2004

Computer keyboard and mouse as a reservoir of pathogens in an intensive care unit.

OBJECTIVE: User interfaces of patient data management systems (PDMS) in intensive care units (ICU), like computer keyboard and mouse, may serve as reservoirs for the transmission of microorganisms. Pathogens may be transferred via the hands of personnel to the patient causing nosocomial infections. The purpose of this study was to examine the microbial contamination of computer user interfaces with potentially pathogenic microorganisms, compared with other fomites in a surgical intensive care unit of a tertiary teaching hospital. METHODS: Sterile swab samples were received from patient's bedside computer keyboard and mouse, and three other sites (infusion pumps, ventilator, ward round trolley) in the patient's room in a 14 bed surgical intensive care unit at a university hospital. At the central ward samples from keyboard and mouse of the physician's workstation, and control buttons of the ward's intercom and telephone receiver were obtained. Quantitative and qualitative bacteriological sampling occurred during two periods of three months each on eight nonconsecutive days. RESULTS: In all 14 patients' rooms we collected a total of 1118 samples: 222 samples from keyboards and mice, 214 from infusion pumps and 174 from the ward's trolley. From the central ward 16 samples per formites were obtained (computer keyboard and mouse at the physician's workstation and the ward's intercom and telephone receiver). Microbacterial analysis from samples in patients' rooms yielded 26 contaminated samples from keyboard and mouse (5.9%) compared with 18 positive results from other fomites within patients' rooms (3.0%; p < 0.02). At the physician's computer terminal two samples obtained from the mouse (6.3%) showed positive microbial testing whereas the ward's intercom and telephone receiver were not contaminated (p = 0.15). CONCLUSIONS: The colonization rate for computer keyboard and mouse of a PDMS with potentially pathogenic microorganisms is greater than that of other user interfaces in a surgical ICU. These fomites may be additional reservoirs for the transmision of microorganisms and become vectors for cross-transmission of nosocomial infections in the ICU setting.

Bacteria↗
PubMed2006

Blastocystis ratti induces contact-independent apoptosis, F-actin rearrangement, and barrier function disruption in IEC-6 cells.

Blastocystis is an enteric protozoan purportedly associated with numerous clinical cases of diarrhea, flatulence, vomiting, and other gastrointestinal symptoms. Despite new knowledge of Blastocystis cell biology, genetic diversity, and epidemiology, its pathogenic potential remains controversial. Numerous clinical and epidemiological studies either implicate or exonerate the parasite as a cause of intestinal disease. Therefore, the aim of this study was to investigate the pathogenic potential of Blastocystis by studying the interactions of Blastocystis ratti WR1, an isolate of zoonotic potential, with a nontransformed rat intestinal epithelial cell line, IEC-6. Here, we report that B. ratti WR1 induces apoptosis in IEC-6 cells in a contact-independent manner. Furthermore, we found that B. ratti WR1 rearranges F-actin distribution, decreases transepithelial resistance, and increases epithelial permeability in IEC-6 cell monolayers. In addition, we found that the effects of B. ratti on transepithelial electrical resistance and epithelial permeability were significantly abrogated by treatment with metronidazole, an antiprotozoal drug. Our results suggest for the first time that Blastocystis-induced apoptosis in host cells and altered epithelial barrier function might play an important role in the pathogenesis of Blastocystis infections and that metronidazole has therapeutic potential in alleviating symptoms associated with Blastocystis.

Actins↗
PubMed1982

Intestinal parasites in asymptomatic adult Southeast Asian immigrants.

All previous studies of intestinal parasites in Southeast Asian refugees have included immigrants with and without symptoms. In order to determine the prevalence of intestinal parasites in asymptomatic Southeast Asians, 226 adult refugees were studied who had no symptoms or signs suggestive of intestinal parasitism and who submitted one to three stools for examination. Fifty-four percent of these asymptomatic adults were infected with one or more potential pathogens, 22 percent with Ascaris, 20 percent with hookworm, 11 percent with Opisthorchis sp, 7 percent with Trichuris, 5 percent with Strongyloides, 5 percent with Giardia, and 2 percent with Entamoeba histolytica. Laotians and Cambodians, persons who stayed in Thai refugees camps, and patients with anemia or eosinophilia were more likely than other refugees to harbor pathogenic parasites. Nonetheless, refugees without these characteristics were often infected, and no single characteristic excluded any refugee from a high probability of being parasitized. There is a high prevalence of potentially pathogenic parasites in asymptomatic adult Southeast Asians, similar to that reported in refugees unselected for the presence or absence of symptoms.

Adult↗
PubMed2000

Pathogenic organisms associated with artificial fingernails worn by healthcare workers.

OBJECTIVE: To determine differences in the identity and quantity of microbial flora from healthcare workers (HCWs) wearing artificial nails compared with control HCWs with native nails. DESIGN: Two separate studies were undertaken. In study 1, 12 HCWs who did not normally wear artificial nails wore polished artificial nails on their nondominant hand for 15 days. Identity and quantity of microflora were compared between the artificial nails and the polished native nails of the other hand. In study 2, the microbial flora of the nails of 30 HCWs who wore permanent acrylic artificial nails were compared with that of control HCWs who had native nails. In both studies, nail surfaces were swabbed and subungual debris was collected to obtain material for culture. Staphylococcus aureus, gram-negative bacilli, enterococci, and yeasts were considered to be potential pathogens. All organisms were identified and quantified. RESULTS: In study 1, potential pathogens were isolated from more samples obtained from artificial nails than native nails (92% vs. 62%; P<.001). Colonization of artificial nails increased over time; by day 15, 71% of cultures yielded a pathogen compared with 21% on day 1 (P=.004). A significantly greater quantity of organisms (expressed as mean log10 colony-forming units +/- standard deviation) was isolated from the subungual area than the nail surface; this was noted for both artificial (5.0+/-1.4 vs. 4.1+/-1.0; P<.001) and native nails (4.9+/-1.3 vs. 3.7+/-0.8; P<.001). More organisms were found on the surface of artificial nails than native nails (P=.008), but there were no differences noted in the quantities of organisms isolated from the subungual areas. In study 2, HCWs wearing artificial nails were more likely to have a pathogen isolated than controls (87% vs. 43%; P=.001). More HCWs with artificial nails had gram-negative bacilli (47% vs. 17%; P=.03) and yeasts (50% vs. 13%; P=.006) than control HCWs. However, the quantities of organisms isolated from HCWs wearing artificial nails and controls did not differ. CONCLUSIONS: Artificial fingernails were more likely to harbor pathogens, especially gram-negative bacilli and yeasts, than native nails. The longer artificial nails were worn, the more likely that a pathogen was isolated. Current recommendations restricting artificial fingernails in certain healthcare settings appear justified.

Adult↗
PubMed1981

Eikenella corrodens empyema in children.

Eikenella corrodens is a slow-growing, Gram-negative, facultative, anaerobic organism that is normally found among oropharyngeal flora. Its isolation as a pathogen is increasingly being reported. Although well documented in the literature on adults, few cases of E corrodens infection have been reported in children. We describe two children with E corrodens pneumonia and empyema. In one, infection was mixed, but in the other the organism was isolated in pure culture. Both patients recovered after therapy with a combination of an antibiotic active in vitro against the organism, and surgical drainage. The diagnosis, bacteriology, and evidence for potential pathogenicity of the organism are reviewed; E corrodens should be considered as a potential pathogen, especially in predisposed patients.

Adolescent↗
PubMed1980

Studies on cross-contamination in the dental clinic.

The purpose of this study was to determine the amount of cross-contamination of potential pathogens currently occurring in the dental hygiene clinic at the Ohio State University. Results of this investigation show that there is a significant amount of cross-contamination in the clinic. Potentially pathogenic organisms were transferred from the patients' mouths to the fingers of the dental hygiene students, and then to the switches on the dental chair unit and to the handles of the sink. Use of 5% iodophor in 70% isopropyl alcohol was effective in sterilizing certain fomes in the dental operatory.

Asepsis↗
PubMed1996

Severe exacerbations of COPD patients: the role of pulmonary infections.

Infection is usually considered the main cause of acute exacerbation in chronic obstructive pulmonary disease (COPD). However, uncertainty persists concerning the exact role of bacterial and viral infection in this setting because of the confusing and conflicting data on the role of tracheobronchial microflora and the usefulness of antibiotics in treating this disease. Most COPD patients have evidence of lower respiratory tract chronic bacterial colonization during remission periods as well as during acute exacerbations. This is evidenced by using microbiological analysis of secretions, which reflect all the respiratory tract (sputum), the lower respiratory tract (transtracheal aspiration), or the distal respiratory tract (protected specimen brush). Potentially pathogenic organisms can be recovered from the respiratory tract secretions of virtually all patients with COPD at some time during the course of their disease. Absence of difference in isolation of potentially pathogenic organisms between remission periods and acute exacerbations suggests that bacterial infection is probably not the predominant cause of acute exacerbations in COPD. In contrast, data indicate that the association between viral infections and acute exacerbations is clearer than that with bacteria, affecting probably more than 20% of cases. The role of antibiotic therapy in acute exacerbations of COPD remains controversial. (1) Clearly, antibiotic therapy is urgently required in COPD patients with pneumonia. (2) Review of the conflicting results of studies evaluating the role of antibiotic therapy for preventing acute exacerbations suggests that there is no clear-cut rationale for prophylactic treatment of infection for all patients with COPD; it seems, however, that such treatment may be of some use in highly selected patients, such as those with many exacerbations in the winter. (3) Similarly, data are conflicting concerning the curative use of antibiotic therapy, with some studies suggesting acceleration of recovery, prevention of acute deterioration, and longer period of freedom from recurrent exacerbations; conversely many patients recover from exacerbations without resorting to an antibiotic. Unfortunately, no clear data identify patients who could benefit from antibiotic treatment, probably justifying most clinicians' choice to treat acute exacerbations as infectious events.

Acute Disease↗
PubMed1992

Conjunctival flora in extended wear of rigid gas permeable contact lenses.

A longitudinal study was performed to examine the effect of rigid gas permeable (RGP) contact lenses (Boston Equalens II and Quantum II) on the conjunctival flora of 45 young healthy subjects. Microbial flora were determined before delivery of lenses. Subjects wore lenses on an extended wear basis, removing them every 7 days for cleaning and disinfection. Cultures were repeated after 2 months of lens wear and the microbial flora were found to be significantly altered compared to the prelens wear results (0.05 greater than p greater than 0.02). Changes to conjunctival flora included an increase in the number of eyes from which potentially pathogenic microorganisms were isolated, an increase in the number of eyes that were culture-negative, and a decrease in the number of eyes harboring only normal conjunctival flora. The increase in potentially pathogenic flora was not specific for Gram-negative bacteria, which are most often associated with infectious keratitis during contact lens wear.

Adolescent↗
PubMed2000

Dynamics of nasopharyngitis in children.

PURPOSE: Our goal was to characterize the dynamics and bacterial interaction of the aerobic and anaerobic flora of nasal discharge of children at different stages of uncomplicated nasopharyngitis. METHODS AND PATIENTS: Serial semiquantitative nasopharyngeal (NP) and quantitative nasal discharge (ND) cultures were taken every 3 to 5 days from 20 children in whom purulent discharge eventually developed (group 1), and a single culture was obtained from a group of 20 who had only clear discharge (group 2). RESULTS: Aerobic and anaerobic bacteria were isolated from all NP cultures. Bacterial growth was present in 8 (40%) NDs of group 2. Only 7 (35%) of the clear NDs of group 1 showed bacterial growth; the number increased to 14 (70%) at the mucoid stage and 20 (100%) at the purulent stage. It declined to 6 (30%) at the final clear stage. The number of species and total number of organisms increased in the NDs of group 1. Group 1 patients had higher recovery rates of Streptococcus pneumoniae and Haemophilus influenzae in their NP cultures than group 2 patients (P < 0.05). During the purulent stage, Peptostreptococcus species were isolated in 15 (75%), Fusobacterium species in 10 (50%), Prevotella species in 9 (45%), H influenzae in 8 (40%), S pneumoniae in 6 (30%), and beta-hemolytic streptococci in 5 (25%) of group 1 NDs. This was higher than their recovery in the clear stages of both groups and the mucoid stage of group 1. A total of 8 organisms capable of interfering with the growth of potential pathogens were isolated from the NPs of group 1, as compared with 35 from group 2 (P < 0.001). CONCLUSIONS: The development of purulent nasopharyngitis is associated with the pre-existing presence of potential pathogens and the absence of interfering organisms.

Antibiosis↗
PubMed1977

Energy deprivation in man--methodological problems and possibilities.

Various approaches to the study of physiological and behavioural effects of energy deprivation are presented and discussed. An experimental, total energy deprivation in 20 healthy human volunteers during an 11-day period, preceded and followed by 4-day control periods, is described. Potentially pathogenic reactions which occurred in spite of precautions are analysed. It is concluded that the present controlled real-life model with acute total energy deprivation serves the purpose of studying hypotheses concerning potentially pathogenic mechanisms occurring in deprivational situations under conditions of natural and man-made catastrophes.

Adult↗