Risk factors for developing peritonitis caused by micro-organisms of enteral origin in peritoneal dialysis patients

OBJECTIVE

To investigate the risk factors associated with the development of peritonitis caused by enteral bacteria in peritoneal dialysis patients, including the prescription of gastric acid inhibitors as a potential risk factor.

DESIGN

Retrospective single-center study.

SETTING

Tertiary university hospital.

PATIENTS AND MAIN OUTCOME MEASURES

Fifty-five patients who entered into our continuous ambulatory peritoneal dialysis (CAPD) program during the last 6 years were included. Multiple logistic regression analysis was used to establish the best determinants over the development of at least one episode of enteric peritonitis. The predictive variables included in the model were: age, gender, diabetic versus nondiabetic, polycystic versus nonpolycystic kidney diseases, history of constipation, presence or absence of moderate/severe malnutrition, peritoneal transport characteristics, peritoneal protein losses, rate of exit-site infections, rate of total peritonitis, intestinal abnormalities, and treatment with inhibitors of gastric acid secretion.

RESULTS

The total number of peritonitis episodes during the studied period was 88, which clustered in 34 of 55 patients. Fourteen (16%) were caused by enteric micro-organisms in 10 patients: Escherichia coli (6), Klebsiella sp (2), Enterobacter sp (1), and Enterococcus sp (5). Nine of 10 patients who developed enteric peritonitis were on gastric acid inhibitors (3 patients on omeprazole and 6 patients on H2-antagonists), while 15 of 45 patients who did not develop enteric peritonitis were on gastric acid inhibitors (all of them on H2-blockers). There were temporal relationships between the start of gastric acid inhibitors and the development of enteric peritonitis in 6 of 9 patients who were on this medication. Four of 10 patients who developed enteric peritonitis had diverticulosis. Ten of 45 patients who did not develop enteric peritonitis had been diagnosed with diverticulosis of the colon or sigmoid prior to entry to CAPD. The unique patient who was not on gastric acid inhibitors and developed enteric peritonitis, had been diagnosed with chronic atrophic gastritis with achlorhydria. By multiple logistic regression analysis, the treatment with gastric acid inhibitors was the only independent variable that entered into the best predictive equation over the development of enteric peritonitis (log likelihood ratio = -26.077, odds ratio = 18; 95% CI odds ratio: 2 - 155).

CONCLUSION

Gastric acid inhibitors may increase the risk for developing enteric peritonitis in peritoneal dialysis patients.

Course and management of renal subcapsular abscess in a 63-year-old diabetic woman

Renal subcapsular abscess is a very rare disease that is defined by a suppurative process localized to a space between the renal capsule and the renal parenchyma. The course and management of subcapsular abscesses have received less attention than those of renal and perirenal abscesses. We describe a 63-year-old diabetic woman who presented with intermittent fever of 1 month's duration. She was initially treated for suspected acute pyelonephritis then referred to our hospital because of poor clinical response to cefazolin plus gentamicin. Computed tomography of the abdomen revealed a huge subcapsular abscess with displacement and compression of the left renal parenchyma. A percutaneous catheter was inserted and left in place for 8 days; a total of approximately 850 mL of pus was drained. Culture of the pus yielded Klebsiella pneumoniae and Enterobacter cloacae. A 2-week course of moxalactam was administered on the basis of the results of in vitro antibiotic susceptibility testing. The distorted renal parenchyma appeared normal at sonographic follow-up examination 3 weeks after hospitalization. The course and management of this rare entity are presented as a reminder to physicians that renal subcapsular abscess could manifest as fever of unknown origin in a diabetic patient. A high degree of clinical suspicion is required for early diagnosis and treatment in order to achieve a satisfactory outcome.

Case of chorioamnionitis in an immunocompetent woman caused by Morganella morganii

Morganella morganii is an opportunistic organism that leads to serious morbidity. It is an enteric organism commonly associated with immunocompromise and chronic urinary catheterization. We present a case of a healthy gravid individual who presented with chorioamnionitis and neonatal seizures associated with M. morganii. This organism, which causes severe morbidity, is fortunately rare in obstetrics and gynecology.

Enterobacter cloacae endophthalmitis: report of four cases

Members of the genus Enterobacter are commensal organisms of the gastrointestinal tract and are considered pathogenic only for patients with lowered resistance to infection (e.g., chronic infection, cancer, or diabetes mellitus) or those with impaired immunity (congenital, acquired, or impaired immunity secondary to therapy). We report on four cases of endophthalmitis caused by Enterobacter cloacae: two in patients with acute postoperative endophthalmitis, one in a patient with delayed bleb-related endophthalmitis, and one in a patient presenting with presumed posttraumatic endophthalmitis. Each patient presented with severe disease many days after the onset of ocular symptoms, and two patients had systemic risk factors accounting for a reduced resistance to infection. Endophthalmitis caused by gram-negative bacilli is characterized by acute onset, rapid progression, and poor final visual outcome. Each of these patients was treated by a standard protocol with intravitreal, systemic, and topical antibiotics and systemic steroids. Despite treatment, the final visual outcomes for three of these patients was no perception of light, and that for one patient remained perception of hand movements only. In common with endophthalmitis caused by other gram-negative organisms, intraocular infection secondary to Enterobacter cloacae infection is a devastating disease which, despite treatment, results in extensive ocular damage and severe visual loss. Since 1966, only four cases of endophthalmitis secondary to infection with members of this genus have been reported. This report presents four cases which occurred over a period of 14 months and, to the best of our knowledge, the first case of bleb-related endophthalmitis secondary to E. cloacae infection.

Citrobacter farmeri bacteremia in a child with short-bowel syndrome

A case of sepsis in a pediatric patient due to the newly described Citrobacter species C. farmeri is described. Factors predisposing this child to infection included short-bowel syndrome requiring total parenteral nutrition.

Use of antibiotic-impregnated polymethyl methacrylate in horses with open or infected fractures or joints: 19 cases (1987-1995)

OBJECTIVE

To evaluate the clinical efficacy of antibiotic-impregnated polymethyl methacrylate (PMMA) in horses with open or infected fractures or joints in which internal fixation or external coaptation devices were used.

DESIGN

Retrospective case series.

ANIMALS

19 horses in which antibiotic-impregnated PMMA was used as part of the treatment regimen.

PROCEDURES

Medical records of each horse were reviewed, and owners and trainers were contacted to provide additional information.

RESULTS

Musculoskeletal problems in these horses included 10 fractures of long bones, 2 comminuted phalangeal fractures, 5 joint injuries, and 2 chronically septic joints in which ankylosis was stimulated. Nine horses had open fractures, 8 had closed wounds and developed infection after internal fixation of fractures, and 2 had chronically septic joints. Bony union was achieved in 15 of 19 horses. Twelve horses were discharged from the hospital and survived long term. Gentamicin sulfate, tobramycin sulfate, amikacin sulfate, and cefazolin sodium were used in PMMA.

CLINICAL IMPLICATIONS

Use of antibiotic-impregnated PMMA provided high local concentrations of antibiotics and should be considered in the treatment of horses with open fractures and acute and chronic bone and joint infections.

[The clinical manifestation and drug sensitive tests of lower respiratory tract infection by enterobacter cloacae. The Pulmonary Infection and Fibrosis Group, Thoracic Society Shanghai Medical Association]

OBJECTIVE

To study the clinical characteristics of lowar respiratory tract infection caused by E. cloacae and to investigate the drug sensitivities of E. cloacae strains.

METHOD

(1) Analysing the clinical deta of 58 case with lowa respiratory tract infection of enterobacter cloacae defined by a putative standard, including ages, symptoms, signs, underlying diseases, sputum culture, X-ray findings and the prognosis. (2) Determining the drug sensitivities against the E. cloacae strains by K-B method.

RESULTS

(1) There were 46 males and 12 females, with the mean age 56 +/- 19% cases diagnosed, who had underlying diseases, most were COPD. 41% cases were mixed infections with other bacteria, most of which were P. aeruginosa and K. pneumoniae. The chief symptoms were fever (72%) and productive cough (87%). The chest X-ray revealed inflammatory infiltration in lower lobes of both sides. The mortality rate was 9%. (2) The antimicrobial tests in vitro showed that these strains were multiresistant to antibiotics, but imipenem, amikacin, tobramycin, ciprofloxacin, cefoaperazone were sensitive.

CONCLUSIONS

The lower respiratory tract infections caused by E. cloacae showed no specific clinical manifestations. However, the mortality was high. The diagnosis should be made according to bacteriologic examination combined with clinical and X-ray manifestations. Combining antibiotics therapy was recommanded according to antimicrobial sensitivity test.

Leclercia adecarboxylata infections: case report and review

Leclercia adecarboxylata has been rarely isolated from environmental and clinical specimens. On review of the world literature, we found two reports of L. adecarboxylata infection: one report described a patient with hepatic cirrhosis, and the other described a child dependent on total parenteral nutrition. L. adecarboxylata was isolated from five infected patients who were evaluated at our institution. Three patients had lower-extremity wound infections in which L. adecarboxylata was part of a mixed microbial growth. One patient had pneumonia due to multiple bacteria, including L. adecarboxylata, which were isolated from sputum. L. adecarboxylata was isolated from the blood of one patient with neutropenia and from the blood of the two patients reported in the literature. All patients except one had fever and leukocytosis. L. adecarboxylata isolates were susceptible to all the antimicrobials tested. L. adecarboxylata is most frequently isolated as part of a mixed microbial growth. Its role in these infections is not clear. However, the organism caused bacteremia in three patients.

Morganella morganii: a newly reported, rare cause of neonatal sepsis

This case report reviews the clinical course of an 11-day-old boy who developed late-onset neonatal sepsis secondary to a rare neonatal pathogen, Morganella morganii. This gram-negative enteric bacterium, within the Enterobacteriaceae family, has most commonly been a nosocomial pathogen in debilitated, postsurgical patients. Like many other Enterobacteriaceae, M. morganii has an inducible beta-lactamase and is resistant to multiple antibiotics. When caring for neonates with culture-proven M. morganii sepsis, the authors recommend administering both a third-generation cephalosporin and an aminoglycoside to ensure that both antibiotics are bactericidal and to reduce the induction of resistance.

Ceftibuten: an overview

Ceftibuten is an orally active third-generation cephalosporin that exhibits good microbiologic activity against many gram-negative and select gram-positive organisms. It is stable against plasmid-mediated beta-lactamases, including extended-spectrum beta-lactamases. Ceftibuten has been shown to be effective in the treatment of upper and lower respiratory tract infections and, although not approved indications, complicated and uncomplicated urinary tract infections in both adults and children. It is readily absorbed (75-90%) after oral administration, with peak serum levels of 17 microg/ml in healthy volunteers. Its half-life is 2.5 hours in healthy volunteers and is increased in elderly patients to approximately 3.2 hours. Elimination occurs primarily through the kidneys, requiring dosage adjustments to be made when creatinine clearance falls below 50 ml/minute. The drug's safety profile is favorable and similar to that of most other cephalosporins. Based on pharmacokinetic information and clinical trial data, ceftibuten can be dosed once/day for most infections. It is an alternative to other currently available antimicrobial agents in the treatment of indicated upper and lower respiratory tract infections.

The use of aztreonam as an alternate therapy for multi-resistant Pseudomonas aeruginosa

The emergence of multi-resistant Gram-negative bacteria has created a most alarming clinical situation. The armamentarium of antibiotics used against this group of organisms is rapidly being depleted. Our routine therapeutic approach to control and prevent these Gram-negative bacteria from gaining a foothold was the empirical use of an aminoglycoside combined with piperacillin. However, aminoglycoside resistance is now routine rather than unusual. We evaluated the role of the monobactam aztreonam in burn wound infections and compared it to the aminoglycosides amikacin and gentamicin as well as piperacillin for the Enterobacteriacae and Pseudomonas aeruginosa. A total of 1274 Gram-negative isolates including P. aeruginosa were evaluated for susceptibility to the above-mentioned antibiotics from January 1995 to August 1995 (Table I). Among the Enterobacteriacae, aztreonam was more effective than amikacin and piperacillin (58.4 per cent vs. 45.8 per cent, respectively). However, it still fluctuated among the Enterobacteriacae as did the aminoglycosides. One major significant finding was that while susceptibility to aztreonam was variable for the Enterobacteriacae, P. aeruginosa remained 90 per cent susceptible to aztreonam and 90 per cent susceptible to piperacillin, whereas it was 79 per cent resistant to the aminoglycosides. Consequently, when choosing an antimicrobial in a suspected P. aeruginosa burn wound infection, aztreonam and piperacillin should be considered as the first line of defense.

[Contribution to the treatment of acute bovine mastitis with cefquinome]

Cefquinome is the first 4th generation cephalosporin antibiotic developed for use in veterinary medicine. A European multicentre study established a high in vitro activity for this modern antimicrobial drug against a wide spectrum of bovine pathogens. Gram-positive and gram-negative mastitis agents were inactivated even at very low active ingredient concentrations, including Enterobacteriaceae which are often resistant to other drugs. The results of clinical trials using experimental E. coli mastitis as an example demonstrate the efficacy of cefquinome in vivo. Parenteral administration at a dose rate of 1 mg/kg body weight when compared with conventional therapy using a control drug with equally good in vitro activity, produced significantly better therapeutic results.

Enterobacter spp.: pathogens poised to flourish at the turn of the century

Knowledge of the genus Enterobacter and its role in human disease has expanded exponentially in recent years. The incidence of infection in the hospital and the community has increased. New clinical syndromes have been recognized. Enterobacter spp. have also been implicated as causes of other syndromes that traditionally have been associated almost exclusively with more easily treatable pathogens, such as group A streptococci and staphylococci. Rapid emergence of multiple-drug resistance has been documented in individual patients during therapy and in populations and environments with strong selective pressure from antimicrobial agents, especially the cephalosporins. Therapeutic options for patients infected with multiply resistant strains have become severely limited. Carbapenems or, alternatively, fluoroquinolones are the most predictively active options, although resistance to both classes has been observed on rare occasions. Enterobacter spp. appear well adapted for survival and even proliferation as the turn of the century approaches.

Cefepime and amikacin synergy against a cefotaxime-susceptible strain of Enterobacter cloacae in vitro and in vivo

We developed an experimental model of pneumonia to evaluate the efficacy of new antibiotic regimens against Enterobacter cloacae. Rats were infected by administering 8.5 log10 cfu E. cloacae intratracheally, and therapy was initiated 24 h later. At that time, animals' lungs showed bilateral pneumonia containing more than 7 log10 cfu/g of tissue. Because rats eliminate amikacin and cefepime much more rapidly than humans, renal impairment was induced in all animals to simulate the pharmacokinetic parameters in humans. Using this model, we compared the bactericidal activities of cefepime and amikacin alone or in combination against the same cefotaxime-susceptible E. cloacae strain. The MICs of cefepime and amikacin for this strain were 0.5 and 2 mg/L, respectively. In-vitro killing studies showed that antibiotic combinations were synergic only at intermediate concentrations. At peak concentrations, the combination was only as effective as amikacin alone. At trough concentrations, a non-significant trend towards the superiority of the combination over cefepime alone was found. In-vivo studies showed that each antibiotic alone failed to decrease bacterial counts in the lungs except at 6 h, whereas the combination of both antibiotics induced a significant decrease in the lung bacterial count 6, 12 and 24 h after the onset of therapy when compared with tissue bacterial numbers in untreated animals or animals treated with either antibiotic alone. In-vivo synergy between cefepime and amikacin was observed at the three time points studied. No resistant clones emerged during treatment with any of the antibiotic regimens studied.

Differential distributions in tissues and efficacies of aztreonam and ceftazidime and in vivo bacterial morphological changes following treatment

The differential tissue distributions of aztreonam and ceftazidime within fibrin clots infected with Pseudomonas aeruginosa, Enterobacter cloacae, and Serratia marcescens, their efficacies, and the in vivo bacterial morphological changes induced by these drugs were evaluated. Rabbits were given intravenously a single dose of 100 mg of either agents/kg of body weight. In the cores of the clots, the peak levels of both drugs were much lower than those observed in the peripheries and in serum. Aztreonam's half-lives within the peripheries and in the cores of the fibrin clots were up to six times higher than observed in serum, while ceftazidime's half-lives in clots were twice that observed in serum. This resulted in a much greater penetration ratio for aztreonam than for ceftazidime. Both drugs controlled the growth of P. aeruginosa in vivo, but E. cloacae and S. marcescens responded better to ceftazidime. Morphological changes were more abundant in the peripheries than in the cores of the clots. In the control group, P. aeruginosa's morphology in the cores was different than that in the peripheries of the clots. Against P. aeruginosa, aztreonam did induce morphological changes in the cores while ceftazidime did not. Electron microscopic studies revealed that morphological changes associated with aztreonam seemed different than those of ceftazidime. Along with elongation of bacteria, more bow tie and herniated bacteria were observed with aztreonam. Though both agents selectively affect PBP 3, as manifested by elongated bacteria, they induce in the peripheries of the clots thickening, breaks, and detachment in bacterial cell walls, alterations which are generally associated with antibiotics affecting PBP 1a and 1b.

Efficacy of cefepime in the treatment of infections due to multiply resistant Enterobacter species

Cefepime is a new cephalosporin with an enhanced antibacterial potency and spectrum. More rapid penetration into many gram-negative bacilli, targeting of multiple penicillin-binding proteins, and resistance to inactivation by many beta-lactamases account for its activity against organisms that have developed resistance to agents such as ceftazidime, cefotaxime, or ceftriaxone. This study identified 16 patients with 17 infections due to Enterobacter species organisms with reduced susceptibility or resistance to ceftazidime. Most isolates were multiply resistant to other beta-lactam drugs as well, but all were susceptible to cefepime. All 17 infections, which included pneumonia, urinary tract infection, intraabdominal infection, and bacteremia, responded clinically to intravenous cefepime. In particular, cefepime was successfully used in the management of cases of chronic infection that had responded poorly to repeated therapy with imipenem, aminoglycosides, or ciprofloxacin. Eradication of Enterobacter species organisms occurred at 15 (88.2%) of the 17 sites of infection. No emergence of resistance to cefepime was noted.