Hypoxia-inducible lipid droplet-associated protein (HILPDA) and cystathionine β-synthase (CBS) co-contribute to protecting intestinal epithelial cells from Staphylococcus aureus via regulating lipid droplets formation

Despite Staphylococcus aureus (S. aureus) being a highly studied zoontic bacterium, its enteropathogenicity remains elusive. Herein, our findings demonstrated that S. aureus infection led to the accumulation of lipid droplets (LDs) in intestinal epithelial cells, accompanied by marked elevation inflammatory response that ultimately decreases intracellular bacterial load. The aforestated phenomenon may be partly attributed to the up-regulation of hypoxia-inducible lipid droplet-associated protein (HILPDA) and the concomitant down-regulation of cystathionine β-synthase (CBS) protein. Moreover, S. aureus infection up-regulated the expression of HILPDA, thereby promoting LDs accumulation, and down-regulated that of CBS, consequently inhibiting microsomal triglyceride transfer protein (MTTP) expression. This process may suppress the transport of LDs to the extracellular environment, further contributing to the formation of intracellular LDs. In summary, the results of this study provide significant insights into the intricate mechanisms through which the host organism combats pathogens and maintains the balance of sulfur and lipid metabolism. These findings not only enhance our understanding of the host's defense mechanisms but also offer promising avenues for the development of novel strategies to combat intestinal infectious diseases.

A systematic review for pursuing the presence of antibiotic associated enterocolitis caused by methicillin resistant Staphylococcus aureus

BACKGROUND

Although it has received a degree of notoriety as a cause for antibiotic-associated enterocolitis (AAE), the role of methicillin resistant Staphylococcus aureus (MRSA) in the pathogenesis of this disease remains enigmatic despite a multitude of efforts, and previous studies have failed to conclude whether MRSA can cause AAE. Numerous cases of AAE caused by MRSA have been reported from Japan; however, due to the fact that these reports were written in the Japanese language and a good portion lacked scientific rigor, many of these reports went unnoticed.

METHODS

We conducted a systematic review of pertinent literatures to verify the existence of AAE caused by MRSA. We modified and applied methods in common use today and used a total of 9 criteria to prove the existence of AAE caused by Klebsiella oxytoca. MEDLINE/Pubmed, Excerpta Medica Database (EMBASE), the Cochrane Database of Systematic Reviews, and the Japan Medical Abstract Society database were searched for studies published prior to March 2013.

RESULTS

A total of 1,999 articles were retrieved for evaluation. Forty-five case reports/series and 9 basic studies were reviewed in detail. We successfully identified articles reporting AAE with pathological and microscopic findings supporting MRSA as the etiological agent. We also found comparative studies involving the use of healthy subjects, and studies detecting probable toxins. In addition, we found animal models in which enteritis was induced by introducing MRSA from patients. Although we were unable to identify a single study that encompasses all of the defined criteria, we were able to fulfill all 9 elements of the criteria by collectively analyzing multiple studies.

CONCLUSIONS

AAE caused by MRSA-although likely to be rarer than previous Japanese literatures have suggested-most likely does exist.

Antibiotic-associated diarrhea: a refresher on causes and possible prevention with probiotics--continuing education article

Antibiotic-associated diarrhea (AAD) describes any unexplained diarrhea associated with the use of an antibiotic. AAD also includes infection caused by Clostridium difficile, however this organism only accounts for a small percentage of diarrhea caused by antibiotics. AAD can be caused by multiple other organisms including C perfringens, S aureus, and Candida. Some antibiotics are more likely to cause non-C difficile AAD, such as erythromycin and the penicillin class. AAD develops through the loss of normal flora and reduced colonic bacterial carbohydrate metabolism during antibiotic administration. There is an increasing interest in the use of probiotics for the prevention of AAD. There are several meta-analyses that report a relative risk reduction of AAD with the use of probiotics during antibiotic administration. Interpretation of these studies has been challenging due to the heterogeneity and size of the patient populations, unclear probiotic regimen, and unclear safety profile. Since AAD can be a reason for a patient to become non-compliant or receive incomplete treatment, clinicians should monitor for this potential adverse effect caused by antibiotics.

Beneficial effects of a strain of Lactobacillus paracasei subsp. paracasei in Staphylococcus aureus-induced intestinal and colonic injury

OBJECTIVES

The aim of this study was to investigate the in vitro and in vivo anti-staphylococcal activity of a lactic acid bacterial strain and its effect on the intestinal histological damage caused by Staphylococcus aureus infection.

METHODS

Lactobacillus paracasei subsp. paracasei was isolated in our laboratory from breastfed newborn feces and identified phenotypically and genotypically. The strain was analyzed by spot-on-lawn and well diffusion assays for the production of bacteriocins against five antibiotic-resistant S. aureus strains isolated from the feces of hospitalized patients with antibiotic-associated diarrhea. The anti-staphylococcal activity of this strain was evaluated in fermented milk and in vivo using holoxenic rabbits.

RESULTS

The strain was able to produce a bacteriocin-like substance active against the staphylococcal strains. A reduction of 2 log in S. aureus cell numbers was registered in co-culture with L. paracasei in fermented milk. Administration of skimmed milk containing S. aureus (10(7) cells/ml) to healthy rabbits induced a persistent diarrheal state 5 days after the challenge. Dissection of the rabbits and consequent histological observations showed damage and an atrophy of the intestinal and colonic mucosae of the diarrheal rabbits; in contrast an arrest of the diarrhea concomitant with recovery of the intestinal villi and the colonic crypts was observed in the rabbits treated with L. paracasei-fermented milk. Furthermore, the diarrheal state persisted in spite of a decrease in the level of S. aureus cells in the feces of the rabbits receiving sterile milk; this was in contrast to the rabbits treated with L. paracasei-fermented milk, in which the decrease in the S. aureus fecal number was associated with the arrest of the diarrhea.

CONCLUSIONS

L. paracasei could act as a potential barrier to prevent S. aureus- associated injury and might exert its effect on the staphylococcal enterotoxins or their target.

Prevalence of Enterotoxin Producing Staphylococcus aureus in Stools of Patients with Nosocomial Diarrhea

BACKGROUND

Nosocomial diarrhea causes prolonged hospital stay leading to additional diagnostic and therapeutic procedures resulting in higher costs. A total of 20%-25% of antibiotic-associated diarrhea (AAD) cases are attributed to Clostridium difficile. Other microorganisms like Clostridium perfringens and Staphylococcus aureus are discussed to be associated with AAD.

PATIENTS AND METHODS

This study evaluated the prevalence of enterotoxigenic S. aureus in stool samples submitted to the laboratory with the diagnosis nosocomial diarrhea. A total of 2,727 stools from clinical patients were investigated for S. aureus and C. difficile. Samples were cultured for both bacteria and a C. difficile toxin A and B assay was performed from all stools. Isolated S. aureus were investigated for enterotoxin production and for resistance against methicillin. In addition, both assays were evaluated for determination of S. aureus enterotoxins directly in stool samples.

RESULTS

Out of 2,727 stools investigated, 198 grew S. aureus and 148 C. difficile. Toxins A/B from C. difficile were detected in 184 stools. A total of 114 S. aureus strains produced the following enterotoxins in vitro: A, 36; B, 20; C, 19; D, 68; E, 2. Both pathogens were found in 25 stools. Twenty-nine (14.6%) S. aureus strains were identified as methicillin-resistant. The two toxin assays evaluated in this study were not able to detect S. aureus enterotoxins directly in stools.

CONCLUSION

The role of enterotoxigenic S. aureus in the pathogenesis of nosocomial and AAD needs further consideration. It might be necessary to investigate stool samples from patients with AAD/nosocomial diarrhea for S. aureus on a routine basis.

Comparative analysis of prevalence, risk factors, and molecular epidemiology of antibiotic-associated diarrhea due to Clostridium difficile, Clostridium perfringens, and Staphylococcus aureus

We prospectively studied the comparative epidemiology and risk factors for Clostridium difficile, Clostridium perfringens, and Staphylococcus aureus antibiotic-associated diarrhea (AAD). Four thousand six hundred fifty-nine inpatient fecal specimens (11 months) were tested for C. difficile cytotoxin, C. perfringens enterotoxin, and S. aureus by Vero cell assay, enzyme-linked immunosorbent assay, and growth on fresh blood agar, respectively. Two distinct age-, sex-, and location-matched control patient groups were used for multivariate logistic regression risk factor analyses: symptomatic patients who were AAD pathogen negative and asymptomatic patients with histories of recent antimicrobial therapy. All AAD pathogen isolates were DNA fingerprinted. In AAD cases, the prevalences of C. difficile cytotoxin, C. perfringens enterotoxin, and S. aureus were 12.7%, 3.3%, and 0.2%, respectively (15.8% overall). Age of >70 years was a common risk factor. Other risk factors for infective AAD and C. difficile AAD included length of hospital stay and use of feeding tubes (length of stay odds ratios [OR], 1.017 and 1.012; feeding tube OR, 1.864 and 2.808). Female gender and use of antacids were significantly associated with increased risk of C. perfringens AAD (OR, 2.08 and 2.789, respectively), but unlike what was found for C. difficile AAD, specific antibiotic classes were not associated with increased risk. A limited number of genotypes caused the majority of C. difficile and C. perfringens AAD cases. Similar to what was found for C. difficile AAD, there was epidemiological evidence of C. perfringens AAD case clustering and reinfection due to different strains. C. difficile AAD was approximately 4 and 60 times more common than C. perfringens AAD and S. aureus AAD, respectively. Risk factors for these AAD pathogens differed, highlighting the need to define specific control measures. There is evidence of nosocomial transmission in cases of C. perfringens AAD.

Frequency and possible infection control implications of gastrointestinal colonization with methicillin-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of health care-associated infections. Multiple factors, including transmission from unrecognized reservoirs of MRSA, are responsible for failure to control the spread of MRSA. We conducted prospective surveillance to determine the frequency of gastrointestinal colonization with MRSA among patients and its possible impact on nosocomial transmission of MRSA. Stool specimens submitted for Clostridium difficile toxin A/B assays were routinely inoculated on colistin-naladixic acid agar plates, and S. aureus was identified by using standard methods. Methicillin resistance was confirmed by growth on oxacillin-salt screening agar. For patients whose stool yielded MRSA, information regarding any previous cultures positive for MRSA or other organisms that would require contact precautions was obtained from the laboratory's computer system. During a 1-year period, 151 (9.8%) of 1,543 patients who had one or more stool specimens screened had MRSA in their stool. Ninety-three (62%) of the 151 patients had no previous history of MRSA colonization or infection. Of these 93, 75 were inpatients. Sixty (80%) of the 75 inpatients with no previous history of MRSA were not under "contact precautions." The 60 patients would have spent an estimated total of 267 days without being placed under contact precautions if their positive stool cultures had not resulted in their being isolated. Placing patients under contact precautions based on their positive stool cultures prevented an estimated 35 episodes of MRSA transmission. We conclude that gastrointestinal colonization with MRSA may serve as an unrecognized reservoir from which transmission of MRSA may occur in health care facilities.

Postoperative methicillin-resistant Staphylococcus aureus enteritis following hysterectomy: a case report and review of the literature

Following a hysterectomy a 43-year-old woman developed colicky abdominal pain and profuse postoperative diarrhoea. Examination was unremarkable and initial investigations revealed a normal plain abdominal X-ray initially, but later there was some small bowel dilatation and evidence of raised inflammatory markers. No cause was identified at exploratory laparotomy 2 days post operation. Flexible sigmoidoscopy was normal. The patient was empirically treated with oral vancomycin for presumed Clostridium difficile diarrhoea, although subsequent stool cultures were negative for the usual intestinal pathogens and C. difficile toxin. The diarrhoea persisted for 9 days. By day 10 stool cultures had grown methicillin-resistant Staphylococcus aureus, establishing the diagnosis. To our knowledge this is the first report of methicillin-resistant S. aureus enteritis following hysterectomy.

Nosocomial antibiotic-associated diarrhea associated with enterotoxin-producing strains of methicillin-resistant Staphylococcus aureus

OBJECTIVES

The aim of this study is to present new evidence that enterotoxin-producing strains of methicillin-resistant Staphylococcus aureus may cause nosocomial antibiotic-associated diarrhea.

METHODS

We conducted a prospective study that utilized standard methods to exclude other bacterial, parasitic, and viral pathogens as causes of nosocomial diarrhea in patients with heavy growth of methicillin-resistant S. aureus in their stool. Staphylococcal enterotoxin assays were performed on S. aureus strains recovered from patients' stools and on stool specimens from affected patients. Retrospective cohort studies compared the severity of diarrhea in patients with methicillin-resistant S. aureus-associated diarrhea with that of patients whose stool did not contain the organism and with patients colonized or infected with enterotoxin-negative methicillin-resistant S. aureus strains.

RESULTS

During an 18-month period, 11 patients had nosocomial antibiotic-associated diarrhea associated with enterotoxin-producing strains of methicillin-resistant S. aureus. Other common bacterial, parasitic, and viral pathogens were excluded. S. aureus strains from the 11 patients produced staphylococcal enterotoxin A, A and B, or D. Eighty-nine percent of patients had the same enterotoxin(s) in stool specimens as produced by the strain recovered from their stool. Case patients had a greater number of days of diarrhea than patients without methicillin-resistant S. aureus in their stool (p < 0.001), or randomly selected patients colonized or infected with enterotoxin-negative methicillin-resistant S. aureus (p < 0.001).

CONCLUSIONS

Our findings provide evidence that enterotoxin-producing strains of methicillin-resistant S. aureus may cause nosocomial antibiotic-associated diarrhea. Greater recognition of this disease should result in more rapid and appropriate treatment of affected patients.

Prevalence and characteristics of bacteria and host factors in an outbreak situation of antibiotic-associated diarrhoea

Antibiotic-associated diarrhoea (AAD) represents a clinical entity leading to prolonged hospital stays and diagnostic and therapeutic procedures, and results in additional costs. The aim of the present study was to assess the prevalence and characteristics of different bacteria in stools of patients with AAD. The reliability of diagnostic procedures under routine conditions was evaluated. Host factors were also analysed. From June 2002 to April 2003 89 cases of diarrhoea were reported at a hospital unit for internal medicine. Clostridium difficile and Clostridium perfringens toxin enzyme-immunoassays (EIAs), and culture for C. difficile, C. perfringens and Staphylococcus aureus were performed on stool samples from all patients. Toxin production was determined in isolated S. aureus strains. In vitro susceptibility of S. aureus for oxacillin and of C. difficile for vancomycin, metronidazole, linezolid, fusidic acid and tetracycline was tested. Host factors, such as age, comorbidities, antibiotic exposure and contact with other patients, were evaluated. Twenty-six stools were positive for C. difficile toxins by an EIA technique, while C. difficile was cultured from 39. C. difficile was isolated from 21 stools that were EIA negative. Additionally, from 28 stools S. aureus and/or C. perfringens could be isolated. Nine samples contained only S. aureus and/or C. perfringens. Thirty-one stools were negative in all tests. All C. difficile isolates were susceptible to vancomycin and metronidazole. Age >60 years, and diseases of the vascular system, the heart, the kidneys and the lungs were identified as risk factors for acquiring C. difficile in this setting (P values < 0.05). Stool culture for C. difficile was shown to be more sensitive than toxin EIA in this study. Risk factors for the acquisition of C. difficile in outbreak situations seem to differ from risk factors in the normal hospital setting. The role of toxin-producing S. aureus in cases of AAD needs further investigation.

Clostridium difficile-associated diarrhea and colitis

Clostridium difficile is a spore-forming toxigenic bacterium that causes diarrhea and colitis, typically after the use of broad-spectrum antibiotics. The clinical presentation ranges from self-limited diarrhea to fulminant colitis and toxic megacolon. The incidence of this disease is increasing, resulting in major medical and economic consequences. Although most cases respond quickly to medical treatment, C difficile colitis may be serious, especially if diagnosis and treatment are delayed. Recurrent disease represents a particularly challenging problem. Prevention is best accomplished by limiting the use of broad-spectrum antibiotics and following good hygienic techniques and universal precautions to limit the transmission of bacteria. A high index of suspicion results in early diagnosis and treatment and potentially reduces the incidence of complications.

Establishment of orally-administered Lactobacillus gasseri SBT2055SR in the gastrointestinal tract of humans and its influence on intestinal microflora and metabolism

AIMS

To investigate the fate of a streptomycin-rifampicin-resistant variant of Lactobacillus gasseri SBT2055 (LG2055SR) and the influence of its oral administration on the composition and metabolism of the intestinal microflora.

METHODS AND RESULTS

Intestinal passage of LG2055SR was monitored by a combination of selection with antibiotics and identification by a randomly amplified polymorphic DNA (RAPD)-PCR METHOD: Composition of intestinal microflora was analysed by the method developed by Mitsuoka et al. (1965, 1974). Establishment of orally-administered LG2055SR in the human intestine was confirmed in this study. LG2055SR ingestion specifically lowered faecal populations of Staphylococcus and faecal contents of p-cresol.

CONCLUSION

LG2055SR and its parent strain, LG2055, are considered to be appropriate candidates for probiotics.

SIGNIFICANCE AND IMPACT OF THE STUDY

It is clarified that LG2055SR has the ability to establish in the human gastrointestinal tract and alters the composition and metabolism of the intestinal microflora and physical characteristics of faeces.

Predominant Staphylococcus aureus isolated from antibiotic-associated diarrhea is clinically relevant and produces enterotoxin A and the bicomponent toxin LukE-lukD

Staphylococcus aureus was isolated as the predominant or only isolate from cultures of stools of 60 patients over 2 years in a university hospital, leading to the collection of 114 isolates. Diarrhea was observed in 90% of the patients. Ninety-eight percent of the patients had received antibiotics in the month before the diarrhea. Ninety-two percent of the S. aureus isolates were methicillin resistant. S. aureus was encountered with antibiotic-associated diarrhea among 47 quite elderly patients affected or not affected by a gastrointestinal disease. Among the antimicrobial treatments, cessation of the previous therapy when possible or rapid application of oral vancomycin therapy was the most appropriate. Analysis of total DNA by pulsed-field gel electrophoresis revealed 27 different SmaI pulsotypes distributed in 15 clusters. The pulsotypes never differed for related isolates from a single patient, even if they originated from patients with bacteremia. S. aureus was not isolated as the predominant isolate in cultures of stools of 57 patients who received an antimicrobial treatment for more than 5 days without diarrhea. Occurence of production of both enterotoxin A and the bicomponent leucotoxin LukE-LukD by the S. aureus isolates was significantly different from that by random isolates. The results strongly suggest that when predominant in stool samples, S. aureus should be considered a possible etiologic agent for some cases of antibiotic-associated diarrhea.

Postoperative clostridium difficile gastroenteritis

Clostridium difficile gastroenteritis can be the cause of an enigmatic postoperative syndrome of high temperature and marked leukocytosis, out of proportion to the initially mild constitutional symptoms. Patients may suffer delayed onset of diarrhea, which will test positive for the C. difficile enterotoxin by latex agglutination. We report 5 cases of C. difficile gastroenteritis that occurred within a 2-year period. We believe that the combination of preoperative bowel preparation, and intraoperative and postoperative systemic antibiotics is the primary operant factor. All patients responded rapidly when oral antibiotics specific for C. difficile were instituted. The sequelae of C. difficile colitis can include toxic megacolon with perforation and peritonitis, increasing the importance of early recognition and appropriate treatment.

Microorganisms and diarrhea in enterally fed intensive care unit patients

Thirty-six intensive care unit patients, receiving aseptic or manually (routine) reconstituted enteral feeding formulas, were evaluated prospectively for the relationship of microbial involvement, gastric pH, and antimicrobial therapy to diarrhea. The routine protocol group had a significantly higher incidence of bacterial contamination than the aseptic protocol group (Fisher's exact test, p less than 0.05). There were no significant direct associations between isolate category (Gram-negative bacilli, Gram-positive cocci, Gram-negative cocci, yeast), gastric pH, or antimicrobials and diarrhea. However, two organisms (Group D Enterococci and yeast) were indirectly implicated in some cases of diarrhea.

Endemic methicillin-resistant Staphylococcus aureus in a special care baby unit: a 2 year review

During January 1987, methicillin-resistant Staphylococcus aureus (MRSA) was isolated for the first time from a baby admitted to the special care baby unit of a large metropolitan hospital. Over a 2 year period, of 1574 babies admitted to the unit, at least 573 (36.4%) became colonized with the organism. Only nine (1.6%) developed significant infectious morbidity and one baby died. Minor infections occurred in a further 35 (6.1%). The outbreak remained uncontrolled despite rigid infection control measures. Subsequent emphasis on hand washing, in-service education and provision of weekly review of the MRSA colonization rates have failed to eliminate the organism from the unit.

Clinical considerations in the diagnosis of antimicrobial agent-associated gastroenteritis

Most gastrointestinal infections secondary to the use of antimicrobial agents that have been documented are related to overgrowth of Clostridium difficile which produces a spectrum from severe pseudomembranous colitis to mild diarrhea or asymptomatic carriage. The most common inducers of pseudomembranous colitis or antimicrobial agent-associated diarrhea are ampicillin, clindamycin, and various cephalosporins, but almost all antimicrobials may cause this problem. Symptoms vary from watery to bloody diarrhea; the extent and severity of the diarrhea, fever, and abdominal cramps and the incidence of complications (such as toxic megacolon and perforation of the bowel) and of fatality are variable. Normal carriage of C. difficile in infants and asymptomatic carriage in adults who have received antimicrobial therapy make it impossible to rely on culture for diagnosis. The presence of cytotoxin or enterotoxin produced by C. difficile is much more reliable diagnostically, but there may be false-positives with this as well, particularly in infants. However, the combination of the appropriate clinical picture and background and presence of toxin usually permit accurate diagnosis. The definitive method of diagnosis, often not feasible to employ, is demonstration by colonoscopy or sigmoidoscopy of the pathognomonic yellow, elevated plaques on the colonic mucosa. Colonoscopy is preferred since the plaques may be restricted to the right colon, particularly in early cases. From the practical standpoint, the best diagnostic test is demonstration of C. difficile toxin.

Antibiotic-associated colitis due to Clostridium difficile: double-blind comparison of vancomycin with bacitracin

A randomized double-blind study was carried out in patients with unresolving antibiotic-associated colitis due to Clostridium difficile, to compare the effect of bacitracin (80,000 U/day) with vancomycin (500 mg/day) on the resolution of symptoms, clearance of organism, and prevention of relapse. Forty-two patients with colitis, 9 of whom had a pseudomembrane, were randomized, 21 patients to each treatment group. The two groups were comparable in age, disease severity, and antibiotic exposure. For a 50% reduction in stool frequency the mean times (+/- SE) were 4.1 +/- 0.4 days for bacitracin and 4.2 +/- 0.4 days for vancomycin. Sixteen patients (76%) had symptom resolution after 7 days of treatment with bacitracin, compared with 18 patients (86%) given vancomycin. Patients who failed to respond were crossed over (blind) to the alternative antibiotic, but tended to be refractory to the alternative medication as well. Vancomycin-treated patients had negative toxin (83% vs. 53%, p = 0.04) and negative stool cultures (81% vs. 52%, p = 0.02) more frequently than did those patients given bacitracin. Similar numbers of patients in each group had symptomatic relapse during 1 mo of follow-up, but most of them relapsed yet again after blinded crossover therapy. Although bacitracin was significantly less effective than vancomycin in clearing C. difficile from the stools, both were of similar value in the control of symptoms in a group of patients with predominantly nonpseudomembranous colitis. In view of its low cost, bacitracin is a reasonable first-line alternative to vancomycin in the treatment of antibiotic-associated colitis.