Postoperative enteritis caused by methicillin-resistant Staphylococcus aureus

Epidemiological Study on Case Definition of Methicillin-Resistant Staphylococcus aureus Enteritis

Background

Methicillin-resistant Staphylococcus aureus (MRSA) enteritis is a condition in which MRSA grows abnormally in the intestine after administration of antimicrobial agents, resulting in enteritis. Patients with MRSA detected in stool culture tests are often diagnosed with MSRA enteritis. However, uncertainty remains in the diagnostic criteria; therefore, we conducted epidemiological studies to define these cases.

Patients and Methods

Patients who tested positive for MRSA by stool culture using selective media 48 h after admission to Kochi Medical School Hospital between April 1, 2012, and December 31, 2022, and did not meet the exclusion criteria were included. We defined MRSA enteritis (Group A) as cases that were responsive to treatment with vancomycin hydrochloride powder, had a Bristol Stool Scale of ≥ 5, and a stool frequency of at least three times per day; all others were MRSA carriers (Group B). Multivariate analysis was performed to risk factors associated with MRSA enteritis.

Results

Groups A and B included 18 (25.4%) and 53 (74.6%) patients, respectively. Multivariate logistic regression analysis showed that a white blood cell count of > 10000/µL (odds ratio [OR], 5.50; 95% confidence interval [CI], 1.12-26.9), MRSA count of ≥ 2+ in stool cultures (OR, 8.91; 95% CI, 1.79-44.3), and meropenem administration within 1 month of stool specimen submission (OR, 7.47; 95% CI, 1.66-33.6) were risk factors of MRSA enteritis.

Conclusion

The case definitions reviewed for MRSA enteritis may be useful as diagnostic criteria.

A Case of Postoperative Methicillin-Resistant Staphylococcus aureus Enterocolitis in an 81-Year-Old Man and Review of the Literature

Patient: Male, 81-year-old

Final Diagnosis: Methicillin-resistant Staphylococcus aureus bacteremia • Methicillin-resistant Staphylococcus aureus enterocolitis

Symptoms: Diarrhea • sepsis

Medication: —

Clinical Procedure: Computed tomography • echocardiography • polymerase chain reaction • whipple procedure

Specialty: Gastroenterology and Hepatology • Infectious Diseases • Surgery

Resistin-like molecule beta, a colonic epithelial protein, exhibits antimicrobial activity against Staphylococcus aureus including methicillin-resistant strains

PURPOSE

Resistin-like molecule beta (RELMβ) is a small cysteine-rich protein secreted by colonic epithelial cells. RELMβ mRNA and protein expressions are dramatically induced by bacterial exposure in germ-free mice. We hypothesized that RELMβ has antimicrobial activity.

METHODS

The antimicrobial activity of RELMβ was screened by an agar spot test and confirmed by a liquid broth test. The amount of RELMβ in human stools was semi-quantified by Western blot analysis. The induction of RELMβ mRNA and protein expression by bacteria was measured by quantitative RT-PCR using LS174T cells. Electron microscopic immunohistochemistry was performed using polyclonal anti-RELMβ antibody.

RESULTS

RELMβ showed antimicrobial activity against S. aureus and all MRSAs examined in a dose- and pH-dependent fashion. Western blot study showed that the amount of RELMβ in healthy human stools was comparable to that exhibiting antimicrobial activity in vitro. Both RELMβ mRNA and protein expression were induced by heat-inactivated S. aureus, but not by E. coli in LS174T cells. Electron microscopic immunohistochemistry showed that RELMβ bound to the cell surface of S. aureus, followed by destruction of the bacterial cytoplasm.

CONCLUSIONS

RELMβ is a colonic antimicrobial protein and its antibacterial activity is species selective. Because RELMβ is abundant in healthy human stool, RELMβ may modulate gut flora.

A case report of postoperative VRSA enteritis: Effective management of rifampicin for vancomycin resistant Staphylococcus aureus enteritis after esophagectomy and colon reconstruction

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In this case report, this patient underwent esophagectomy, total resection of the gastric remnant, and colon reconstruction, and it is likely that methicillin-resistant Staphylococcus aureus (MRSA) from the upper airway system, which is not exposed to gastric acid, proliferated in the interposed colon and resulted in MRSA enteritis.

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Vancomycin-resistant Staphylococcus aureus (VRSA) arises from MRSA through the transfer of vancomycin resistant genes on the vanA operon to S. aureus.

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This case report describes the potential for rifampicin to be used as an effective treatment choice for postoperative VRSA enteritis.

Introduction

Vancomycin is one of the most widely used antibiotics for the treatment of serious infectious caused by methicillin-resistant Staphylococcus aureus (MRSA). However, reduced susceptibility of S. aureus to vancomycin has been observed in recent years. We report on a case of vancomycin resistant methicillin-resistant Staphylococcus aureus (VRSA) enteritis after colon reconstruction followed by esophagectomy and completion gastrectomy, with extended lymph node dissection for esophageal squamous cell carcinoma.

Presentation of case

A 66-year old male was referred to our hospital for esophageal carcinoma of clinical stage T3 N0 M0, Stage IIA. From the postoperative day 3, the patient reported heavy watery stools on more then 10 occasions and high fever, and was diagnosed with the methicillin-resistant Staphylococcus aureus (MRSA) enteritis. We administered vancomycin to treat the enteritis, although a subsequent stool culture indicated VRSA instead of MRSA. Rifampincin treatment was initiated and the patient’s symptoms improved.

Discussion

In this case report, this patient underwent esophagectomy, total resection of the gastric remnant, and colon reconstruction, and it is likely that methicillin-resistant Staphylococcus aureus (MRSA) from the upper airway system, which is not exposed to gastric acid, proliferated in the interposed colon and resulted in MRSA enteritis.

Conclusions

Rifampicin represents an effective treatment strategy for postoperative VRSA enteritis.

Colonic Perforation Caused by Methicillin-Resistant Staphylococcus aureus Enteritis After Total Gastrectomy: A Case Report

A 68-year-old man underwent total gastrectomy and splenectomy for adenocarcinoma and low anterior resection for carcinoma in tubulo-villous adenoma of the rectum. Broad-spectrum antibiotics were administered for postoperative pancreatic fistula. Methicillin-resistant Staphylococcus aureus enteritis occurred on the 50th postoperative day and cecal perforation followed. The patient underwent construction of cecostomy with peritoneal drainage, and vancomycin was administered orally and per cecostomy for 2 weeks. The patient recovered well and was discharged at 35 days after re-operation in good general condition.

Methicillin-resistant Staphylococcus aureus enterocolitis sequentially complicated with septic arthritis: a case report and review of the literature

BACKGROUND

Although most reports describing patients infected with methicillin-resistant Staphylococcus aureus enterocolitis have been published in Japan, this concept remains a matter of debate and diagnostic criteria have not yet been defined.

CASE PRESENTATION

The general status of a 74-year-old Japanese man referred to our hospital (day 1) with severe community-acquired pneumococcal pneumonia gradually improved with antibiotic therapy. Thereafter, up to 4 L/day of acute watery diarrhea that started on day 19 was refractory to metronidazole but responded immediately to oral vancomycin. Gram staining stool samples was positive for abundant fecal leukocytes from which dominant methicillin-resistant Staphylococcus aureus (10(4) CFU/mL) were isolated, suggesting methicillin-resistant Staphylococcus aureus enterocolitis. High fever with methicillin-resistant Staphylococcus aureus bacteremia was evident at day 30, and suppurative right hip arthritis developed around day 71. All methicillin-resistant Staphylococcus aureus strains isolated from stools, blood and aspirated synovial fluid separated in the same manner on pulsed-field gel electrophoresis, as well as two other strains isolated from sputum, belonged to the same clone as sequence type (ST) 764 (complex clonal 5), and carried SCCmec type II.

CONCLUSION

The clinical, microbiological and molecular biological findings of this patient indicated methicillin-resistant Staphylococcus aureus enterocolitis that led to septic methicillin-resistant Staphylococcus aureus arthritis.

Validation of the 3-day rule for stool bacterial tests in Japan

OBJECTIVE

Stool cultures are expensive and time consuming, and the positive rate of enteric pathogens in cases of nosocomial diarrhea is low. The 3-day rule, whereby clinicians order a Clostridium difficile (CD) toxin test rather than a stool culture for inpatients developing diarrhea >3 days after admission, has been well studied in Western countries. The present study sought to validate the 3-day rule in an acute care hospital setting in Japan.

METHODS

Stool bacterial and CD toxin test results for adult patients hospitalized in an acute care hospital in 2008 were retrospectively analyzed. Specimens collected after an initial positive test were excluded. The positive rate and cost-effectiveness of the tests were compared among three patient groups.

PATIENTS

The adult patients were divided into three groups for comparison: outpatients, patients hospitalized for ≤3 days and patients hospitalized for ≥4 days.

RESULTS

Over the 12-month period, 1,597 stool cultures were obtained from 992 patients, and 880 CD toxin tests were performed in 529 patients. In the outpatient, inpatient ≤3 days and inpatient ≥4 days groups, the rate of positive stool cultures was 14.2%, 3.6% and 1.3% and that of positive CD toxin tests was 1.9%, 7.1% and 8.5%, respectively. The medical costs required to obtain one positive result were 9,181, 36,075 and 103,600 JPY and 43,200, 11,333 and 9,410 JPY, respectively.

CONCLUSION

The 3-day rule was validated for the first time in a setting other than a Western country. Our results revealed that the "3-day rule" is also useful and cost-effective in Japan.

Nasal MRSA screening for surgical patients: predictive value for postoperative infections caused by MRSA

PURPOSE

Postoperative methicillin-resistant Staphylococcus aureus (MRSA) infections are occasionally fatal. We hypothesized that nasal MRSA screening might predict the risk of postoperative MRSA infections. The aim of the current study was to elucidate the relationship between the positivity of nasal MRSA screening and postoperative MRSA infections.

METHODS

Six hundred and fourteen surgical patients who were admitted to the intensive care unit and underwent nasal MRSA screening between April 2006 and March 2011 were divided into MRSA-positive and -negative groups. The incidence of postoperative MRSA infections in the MRSA-positive and MRSA-negative groups were compared, and various risk factors for MRSA infections were evaluated.

RESULTS

The incidence of postoperative MRSA infections, such as pneumonia and enteritis, in the MRSA-positive group was significantly higher than that in the MRSA-negative group (41.9 vs. 3.1 %). The significant independent risk factors for postoperative MRSA infections were a positive MRSA screening, an operation lasting more than 300 min and an emergency operation. A positive MRSA screening was the most statistically significant risk factor for postoperative MRSA pneumonia and enteritis, but was not a risk factor for MRSA surgical site infections.

CONCLUSION

Nasal MRSA screening can help to identify patients who have an increased risk of developing postoperative MRSA infections, and would enable physicians to take a prompt action if these complications occur.

Efficacy of two novel 2,2'-bifurans to inhibit methicillin-resistant Staphylococcus aureus infection in male mice in comparison to vancomycin

The therapeutic efficacy of two novel bifurans and vancomycin in an animal model of a methicillin-resistant Staphylococcus aureus (MRSA) infection was compared. Adult male CF-1 mice (25-35 g) were intraperitoneally injected with 200 μL/mouse containing 10(7) cell-forming units of MRSA. After 16 hours, animals were treated with 110 mg/kg of vancomycin, or 5 mg/kg of mononitrile bifuran (1A) or monocationic bifuran (1B) and killed after 8 hours. Treatment with bifurans did not cause any toxicity. Treatment of MRSA-infected animals with bifurans resulted in significant reductions in the viable bacterial count in blood, liver, kidney, and spleen. Colonies recovered from livers and kidneys of mice injected with 1A or 1B lost the initial resistance pattern and became susceptible to methicillin and ciprofloxacin. MRSA elevated the serum urea level and activities of alanine aminotransferase and γ-glutamyl transpeptidase. MRSA also elevated the hepatic level of malondialdehyde, and serum levels of tumor necrosis factor and interleukin-6. MRSA also reduced the glutathione content and activities of catalase and glutathione S-transferase in liver. Similar to vancomycin, bifurans ameliorated most of the previous effects. Compound 1B was superior to 1A, and sometimes both provided better antistaphylococcal agents than vancomycin against MRSA pathogenesis. The present findings along with our previous studies support further evaluation of the efficacy of these bifurans in clinical studies.

Outbreak of Neonatal Diarrhea in Farmed Mink Kits (Mustella vison) Associated With Enterotoxigenic Staphylococcus delphini

An outbreak of diarrhea on a large commercial mink farm affected 5,000 of 36,000 neonatal mink kits, with 2,000 dying within a 2-week period. Affected kits were severely dehydrated, and their furcoats and paws were covered with yellow- to green-tinged mucoid feces. On necropsy, the small intestines of examined animals were markedly distended by serous to mucoid fluid. Microscopically, there was prominent colonization of the intestinal villar epithelium by gram-positive bacterial cocci in the absence of inflammation and morphologic changes in villous enterocytes. The colonizing bacteria were phenotypically identified as belonging to the Staphylococcus intermedius group of bacteria. This was confirmed by nucleic acid sequence analysis of the 16S ribosomal RNA gene. Further nucleic acid sequencing of polymerase chain reaction (PCR) amplicons from the superoxide dismutase gene and the heat shock protein 60 gene differentiated the isolate as Staphylococcus delphini. Production of staphylococcal enterotoxins A and E was demonstrated with a commercial ELISA-based immunoassay. Sequencing of PCR amplicons confirmed the presence of the enterotoxin E gene, but PCR amplification of the enterotoxin A, B, C, or D genes was not successful. Although direct causation was not confirmed in this study, the authors postulate that the observed hypersecretory diarrhea in these mink kits was the result of colonization of the small intestine by S delphini and subsequent production of enterotoxin.

Changes in the agr locus affect enteritis caused by methicillin-resistant Staphylococcus aureus

We studied the characteristics of methicillin (meticillin)-resistant Staphylococcus aureus (MRSA) strains that caused enteritis. In a previous report, we demonstrated that both phenotypic and genotypic changes were associated with MRSA enteritis; and we hypothesized that the accessory gene regulator (agr), which is a global regulator of staphylococcal virulence and upregulates several exoproteins, is the key factor associated with the development of MRSA enteritis. In this study, we examined 12 MRSA isolates associated with enteritis from stool samples and 17 MRSA isolates not associated with enteritis that had the following characteristics: the strains associated with enteritis had the same genotype (genotype A), as detected by pulsed-field gel electrophoresis, or the strains were isolated from stools. The differences between strains that caused enteritis and those that did not cause enteritis strains were examined by quantitative reverse transcription-PCR to assess RNAII, agrA, RNAIII, and tst expression and by sequencing of the agr locus. The levels of expression of agrA, RNAIII, and tst were higher by the MRSA isolates associated with enteritis than by the MRSA isolates not associated with enteritis, whether or not they were of the same genotype. The levels of expression of RNAII by almost all the clinical isolates were similar. Sequencing of the agr locus showed that all MRSA isolates that caused enteritis have agr mutations, whereas the MRSA isolates that did not cause enteritis, with three exceptions, did not. Many of the isolates associated with enteritis had the same mutation, especially at the C-terminal end of agrA. These results suggest a trend in which mutations in the agr locus modify the expression of agrA and RNAIII and the production of toxin, all of which may increase the virulence and influence the occurrence of MRSA enteritis.

MRSA enteritis causing a high stoma output in the early postoperative phase after bowel surgery

INTRODUCTION

Nosocomial MRSA infection has become an important healthcare issue. We present 6 cases of MRSA enteritis, acquired following bowel surgery and ileostomy formation.

PATIENTS AND METHODS

The data set was obtained from the experience of one consultant surgeon over 6 years in one medical centre. The clinical features and course of six patients that developed MRSA enteritis postoperatively were obtained through review of case notes and laboratory data.

RESULTS

Four male and two female patients (age range, 22-80 years) developed a clinical syndrome postoperatively requiring treatment within the high dependency unit. Three developed respiratory distress syndrome, and one died from multi-organ failure. Exploratory laparotomy carried out in three patients was negative. All patients were MRSA-negative on admission but had swabs positive for MRSA from ileostomy site postoperatively. All of the three patients who had ileostomy effluent cultured for MRSA had positive results.

DISCUSSION

Fever, abdominal pain, distension and high stoma output in the early postoperative period following bowel surgery should alert the clinician to the possibility of MRSA enteritis. Patients require aggressive resuscitation and culture of ileostomy effluent for MRSA. Exploratory laparotomy has no obvious benefits. As MRSA enteritis has the potential to be a lethally effective disseminator of MRSA, such clinical features should prompt early instigation of appropriate infection control practices.

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.

Molecular epidemiology of enteritis-causing methicillin-resistant Staphylococcus aureus

In the early 1990s, severe enteritis caused by methicillin-resistant Staphylococcus aureus (MRSA enteritis) was prevalent in Japan, but the incidence has since decreased. We compared the genotypes and phenotypes of 12 isolates that caused MRSA enteritis (enteritis isolates), detected between 1990 and 1993, with 186 non-enteritis isolates detected between 1998 and 2002. Organisms were investigated using pulsed-field gel electrophoresis (PFGE), coagulase typing and reverse passive latex agglutination to detect production of staphylococcal enterotoxins (SE) and toxic shock syndrome toxin-1 (TSST-1); and polymerase chain reaction (PCR) for detection of the structural genes entA, entB, entC, entD and tst, which encode proteins SE-A, SE-B, SE-C, SE-D and TSST-1, respectively. The 12 enteritis isolates were classified into four types and four subtypes. Only seven of the 186 non-enteritis isolates had PFGE patterns indistinguishable from the enteritis isolates. Eight of the 12 enteritis isolates had entA, entC and tst, and produced high levels of SE-A and TSST-1, but not SE-C. Of the 186 non-enteritis isolates, 157 produced SE-C and TSST-1, but not SE-A. The seven non-enteritis isolates with a PFGE pattern indistinguishable from the enteritis isolates did not produce SE-A, and showed relatively low levels of TSST-1 production. These isolates may have continued to inhabit our ward since the earlier outbreak, but acquired a different phenotype. In conclusion, the disappearance of MRSA enteritis may have resulted from the decreased incidence of enteritis-causing clones and phenotypical changes.

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.

Diarrhées associées aux antibiotiques chez le sujet âgé

PURPOSE

Most of the antibiotic-associated diarrhea (AAD) cases result from a transient disturbance in the function of the normal intestinal flora and are spontaneously solved when discontinuing the antibacterial therapy. However, a mild diarrhea lasting several days may induce a dehydration or worsen a denutrition in frail elderly people.

CURRENT KNOWLEDGE AND KEY POINTS

The incidence of AAD varies between 5 and 25% depending on the concerned antibiotic. Only 10-20% of all AAD cases are caused by infection, especially with Clostridium difficile, for which advanced age is a major risk factor. The first biological exam to perform when severe AAD or in frail people is the detection of C. difficile toxins, especially in elderly patient treated with beta-lactam antibiotics. Nevertheless, other infectious organisms causing AAD may be considered, as Staphylococcus aureus when predominant in stool cultures from patients treated with fluoroquinolones or as Klebsiella oxytoca when isolated in bloody diarrhea from patients treated with ampicillin. Elevated fecal counts of Candida spp. found in patients treated with antibiotics is rather the consequence of therapy than the cause of AAD. The prevention of AAD is based on a rational antibiotic use to avoid endogenous selection of C. difficile and on the improvement of the hygiene measures to limit the exogenous transmission of the bacteria or related spores by spoiled hands.

FUTURE PROSPECTS

Simultaneous prescription of non-pathogenic living organisms, capable of re-establishing the equilibrium of the intestinal flora, should be better described, especially in elderly people, because of its important economic impact.

A mouse model for postoperative fatal enteritis due to Staphylococcus infection

BACKGROUND

Postoperative infection of intestine with methicillin-resistant Staphylococcus aureus (MRSA) is fatal in some cases. The object of this study was to establish a mouse model for the infection, providing a useful tool for investigating mechanisms in the progression of infection.

METHODS

Mice were pretreated with cyclophosphamide, injected orally or directly into jejunum with MRSA prepared from a postoperative patient, and then given 5 daily doses of antibiotics. Forty-eight hours after the injection, bacterial translocation and serum endotoxin levels were examined. Macrophage depletion was carried out by the administration of liposome-encapsulated dichloromethylene diphosphate (Cl(2)MDP), 4 days before MRSA injection.

RESULTS

Injection into the jejunum but not oral administration of MRSA induced enteritis with diarrhea and resulted in death in most cyclophosphamide-treated mice. Translocation of MRSA in mesenteric lymph nodes and liver was observed, concomitantly with E. coli infection. Endotoxin-resistant C3H/HeJ mice infected with MRSA survived longer than endotoxin-sensitive C3H/He mice, but also died within a week after MRSA injection. Selective depletion of macrophages induced infection in mice that were not pretreated with cyclophosphamide.

CONCLUSION

We established a mouse model for the fatal MRSA infection which induced enteritis with diarrhea, that will be a useful tool for investigating the mechanisms for sometimes fatal MRSA infection of the intestine in postoperative patients. The presence of E. coli or endotoxin seemed to play a major role in the mortality of mice in the early days of MRSA-induced enteritis, but other factors, probably from MRSA, in the later days. Phagocytes were quite important for protection against the MRSA infection.

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.

New methods of control against postoperative methicillin-resistant Staphylococcus aureus infection

The incidence of postoperative infections caused by methicillin-resistant Staphylococcus aureus (MRSA) in Japan has been increasing dramatically. In March 1990, we assigned special doctors in infection control (infection control doctor, ICD), and defined comprehensive controls against MRSA infection. A total of 3536 cases of digestive tract surgery performed at our department were studied during the period between September 1987 and August 1997. We changed the use of antibiotics to prevent postoperative infection. Cefazolin (CEZ) was employed for surgery of the upper digestive tract, including esophagus, stomach, duodenum, and gallbladder. Cefotiam (CTM) was employed for surgery of the lower digestive tract, liver, and pancreas. In esophageal resection, the tracheal tube was extracted during the early postoperative period, and for cervical esophagogastroanastomosis, the autosuture was changed to layer-to-layer anastomosis. We have achieved successful control of postoperative MRSA infection, the incidence having decreased to 0.3% (9/2703). In conclusion, our methods of control against postoperative MRSA infection implies that comprehensive measures of prevention, including the reviewed specification and usage of antibiotics and operation management, have been well implemented. This value is the lowest and the first of any domestic hospital or institute in Japan, suggesting a continued and significant decrease.

Changes in intestinal flora after administration of panipenem/betamipron or sulbactam/cefoperazone for treatment of postoperative infections in gastrectomy patients

To determine the effect of antibiotics used for the treatment of postoperative infections on the normal intestinal flora in patients who have undergone gastroenterological surgery, we performed a prospective randomized study in patients who had undergone distal gastrectomy. Cefazoline was administered up to postoperative day 3 for prophylaxis. For the treatment of postoperative infections, either panipenem/betamipron (PAPM/BP; n = 5) or sulbactam/cefoperazone (SBT/CPZ; n = 5) was adminstered to ten patients with signs of postoperative infections. Feces were examined for bacteria before and 4 and 7 days after the commencement of administration of these therapeutic antibiotics. The anaerobic bacterial count decreased significantly in four of five patients treated with SBT/CPZ, from 1010.2+/-0.36/g before treatment to 105.22+/-3.51/g. In the PAPM/BP-treated group, the anaerobic bacterial count did not change after antibiotic therapy. We also investigated the major genera of colonic anaerobes, and found that the numbers of bifidobacteria were maintained during PAPM/BP administration. However, in the SBT/CPZ group, the number of bifidobacteria decreased to below the detection limit in four of five patients. Little change was observed in the aerobic bacterial count in either group. However, Enterobacteriaceae were replaced by enterococcus or candida in all patients from the SBT/CPZ group and in one of five patients from the PAPM/BP group. Physicians should be alert for the possible clinical consequences of changes in intestinal microflora after antibiotic treatment of postoperative infections.