Recent developments in the understanding of the pathogenesis and treatment of anaerobic infections (2)

Lemierre syndrome with thrombosis of sigmoid sinus following dental extraction: a case report

Lemierre syndrome is caused by an infection in the oropharyngeal region with subsequent thrombophlebitis in the internal jugular vein. The thrombus from the thrombophlebitis can invade other vital organs, such as liver, lungs, or joints, resulting in secondary infection, which further exacerbates the fatal prognosis of this syndrome. Lemierre syndrome, also called postanginal sepsis or necrobacillosis, was first reported by Dr. Lemierre in 1936. In his report, Lemierre mentioned that out of 20 patients who suffered from this syndrome, only two survived. He also stated that all of the 20 patients complained of infections in the palatine tonsils and developed sepsis and thrombophlebitis in the internal jugular vein. Once called a "forgotten disease," this syndrome showed a very high mortality rate until usage of antibiotics became prevalent. In this case report, the authors present a 71-year-old female patient who suffered from Lemierre syndrome with thrombosis extended to the right sigmoid sinus.

Factors associated with septic shock and mortality in generalized peritonitis: comparison between community-acquired and postoperative peritonitis

Introduction

The risk factors associated with poor outcome in generalized peritonitis are still debated. Our aim was to analyze clinical and bacteriological factors associated with the occurrence of shock and mortality in patients with secondary generalized peritonitis.

Methods

This was a prospective observational study involving 180 consecutive patients with secondary generalized peritonitis (community-acquired and postoperative) at a single center. We recorded peri-operative occurrence of septic shock and 30-day survival rate and analyzed their associations with patients characteristics (age, gender, SAPS II, liver cirrhosis, cancer, origin of peritonitis), and microbiological/mycological data (peritoneal fluid, blood cultures).

Results

Frequency of septic shock was 41% and overall mortality rate was 19% in our cohort. Patients with septic shock had a mortality rate of 35%, versus 8% for patients without shock. Septic shock occurrence and mortality rate were not different between community-acquired and postoperative peritonitis. Age over 65, two or more microorganisms, or anaerobes in peritoneal fluid culture were independent risk factors of shock. In the subgroup of peritonitis with septic shock, biliary origin was independently associated with increased mortality. In addition, intraperitoneal yeasts and Enterococci were associated with septic shock in community-acquired peritonitis. Yeasts in the peritoneal fluid of postoperative peritonitis were also an independent risk factor of death in patients with septic shock.

Conclusions

Unlike previous studies, we observed no difference in incidence of shock and prognosis between community-acquired and postoperative peritonitis. Our findings support the deleterious role of Enterococcus species and yeasts in peritoneal fluid, reinforcing the need for prospective trials evaluating systematic treatment against these microorganisms in patients with secondary peritonitis.

Prognostic factors and impact of antibiotherapy in 117 cases of anaerobic bacteraemia

Bacteraemia due to anaerobic bacteria occurs infrequently, making the systematic use of an anaerobic blood sample bottle in patients with sepsis controversial. We retrospectively reviewed the clinical and microbiological data from all cases of anaerobic bacteraemia in a teaching hospital over 2 years and determined the prognostic factors and antibiotic management. With the goal of evaluating the morbidity and mortality of bacteraemia due to anaerobic bacteria, a case-control study was also performed. One hundred eighty-four blood cultures from 125 patients grew at least one anaerobic bacterium, representing 0.5% of all and 7.0% of the positive blood cultures. One hundred seventeen patients were studied. In 24 cases, anaerobic blood cultures were associated with concomitant aerobic bacteria isolation. The most frequently isolated anaerobic species were Bacteroides sp. (n = 62), Clostridium sp. (n = 25), and Fusobacterium sp. (n = 12). The most frequent site of origin was the digestive tract (n = 61). In 51 cases, patients did not receive adequate empirical antianaerobic therapy. The mortality rate was 27%. Age [odds ratio (OR) 1.059; 95% confidence interval (CI) 1.021-1.100], cancer history (OR 3.21, 95% CI 1.126-9.156), and ineffective definitive antibiotherapy (OR 19.292, 95% CI 5.330-69.832) were independently associated with increased hospital mortality. The 72 patients that could be matched with patients without anaerobic bacteria according to their primary diagnosis had a longer hospitalisation and a trend toward increased mortality (P = 0.08). Anaerobic bacteraemia contributed significantly to the morbidity of the patients, and adequate empirical antibiotherapy may play an important role in the clinical outcomes.

Past administration of beta-lactam antibiotics and increase in the emergence of beta-lactamase-producing bacteria in patients with orofacial odontogenic infections

OBJECTIVE

The purpose of this study was to determine the current status of beta-lactamase-producing bacteria in orofacial odontogenic infections.

STUDY DESIGN

Microbiologic data regarding purulent exudate from 111 cases with orofacial odontogenic infections were analyzed in relation to the past administration of beta-lactams.

RESULTS

beta-lactamase-producing bacteria were isolated more frequently from the beta-lactam-administered group (38.5%) than from the beta-lactam-nonadministered group (10.9%; P <.005), and they were isolated more frequently as the duration of administration increased. The predominant bacteria isolated included Prevotella (the most frequent isolate), viridans streptococci, Peptostreptococcus, and Fusobacterium, and 7.1% of total isolates produced beta-lactamase. Penicillin and cefazolin worked well with beta-lactamase-nonproducing Prevotella but were remarkably affected by beta-lactamase-producing Prevotella. Cefmetazole, sulbactam/cefoperazone, and imipenem worked well against both types of Prevotella.

CONCLUSIONS

beta-lactams are still suitable for the first antimicrobial therapy in the treatment of these infections. However, because past beta-lactam administration increases the emergence of beta-lactamase-producing bacteria, beta-lactamase-stable antibiotics should be prescribed to patients with unresolved infections who have received beta-lactams.

[Clostridium perfringens meningitis with fatal outcome in a 3-week old infant]

BACKGROUND

Clostridium perfringens meningitis is a rare condition usually associated to skull injuries, surgery or gastro-intestinal disorders.

CASE REPORT

A 21 day-old infant was admitted for the sudden worsening of a neonatal post-hemorrhagic hydrocephalus. Eighteen hours after admission, she developed a septic status with acute meningitis. A CT scan revealed the presence of intracerebral gas suggesting the responsibility of an anaerobic bacterium. The infant died within 24 hours from multiorgan failure, hemodynamic disorders, acute anemia with red urines. Clostridium perfringens was isolated both from the blood and CSF.

CONCLUSIONS

The tissue alterations following meningeal hemorrhage may favor anaerobic growth. The presence of intracerebral gas is highly suggestive of the diagnosis. The prognosis is very poor.

Antibiotic susceptibility of clinical isolates of Prevotella bivia in Lagos, Nigeria

The susceptibility of 40 clinical isolates of Prevotella bivia to 11 anti-anaerobic agents was determined by disk diffusion and agar dilution methods in accordance with the NCCLS (1990) recommended guidelines. With the disk diffusion method all the P. bivia tested were susceptible to rifampicin, cefoxitin, chloramphenicol, clindamycin and metronidazole. Twelve (30%) isolates were resistant to cefotaxime and ceftriaxone while 2 (5%) each were resistant to tetracycline and erythromycin. Worthy of note, 39 (97.5%) and all 40 (100%) isolates were resistant to ampicillin and penicillin respectively. Determination of minimum inhibitory concentrations (MIC) showed that the first set of 5 antibiotics, except rifampicin, were shown to be as active against all the strains tested as with the disk diffusion sensitivity method: cefoxitin, chloramphenicol, clindamycin and metronidazole had MIC90 values ranging from 0.5-1 microgram/ml. The MIC90s of erythromycin and tetracycline were 4 micrograms/ml each while the range of MIC of cefotaxime and ceftriaxone was 0.5-32 micrograms/ml with a MIC90 of 8 micrograms/ml, well below their breakpoints, which is somewhat at variance with disk diffusion results. The clinical significance of this, however, is not clear, especially in the absence of controlled clinical trials. Ampicillin and penicillin MIC90 values were 64 micrograms/ml and 80 U/ml respectively which essentially confirmed the resistance observed by the disk method. All the P. bivia isolates were beta-lactamase producers, hence the resistance of these isolates to penicillin and ampicillin. It is conceivable that in infections with monoculture of P. bivia, agents like tetracycline, or erythromycin may still be a useful alternative for treatment.

Management of maxillofacial infections: a review of 50 cases

Maxillofacial infections often place the oral and maxillofacial surgeon in situations where timely decisions have to be made. These decisions can be life-saving. This study reviews 50 infections treated over a 3-year period. The results reveal rapid resolution of the infections by adhering to fundamental principles in their management: recognition of airway compromise, surgical intervention, and the administration of the appropriate antibiotic. A protocol for the management of maxillofacial infections is described.

Anaerobic bacteremia: a retrospective four-year analysis in general medicine and cancer patients

Anaerobic bacteremia was studied in 32 medical patients (mean age 72 years) in a four-year retrospective analysis. Malignancy was the most common underlying disease and probable portal of entry. The gastrointestinal tract was affected most often, followed by the respiratory and urinary tracts. Bacteremia occurred either following invasive (non surgical) procedures or spontaneously. The clinical course ranged from asymptomatic bacteremia, to mild febrile illness, to sepsis and septic shock (two, 12, 16 and two patients, respectively). The case fatality rate was 25%. The causative organisms were Clostridium and Bacteroides species. All organisms isolated were susceptible to chloramphenicol. Early diagnosis and prompt treatment may reduce mortality in cases of anaerobic sepsis.

Ampicillin and ampicillin-sulbactam dilution tests with mixed cultures of Bacteroides fragilis, Escherichia coli and Enterococcus

Bacterial interactions in mixed infections may compromise antimicrobial therapy. The in vitro bactericidal activity of ampicillin and ampicillin-sulbactam against aerobic/anaerobic mixed cultures of Bacteroides fragilis, Escherichia coli and Enterococcus spp. was studied by means of broth dilution tests. The MBC of ampicillin for Enterococcus faecalis 6 was 0.25 mg/l when tested singly; in association with B. fragilis 1, however, the MBC for E. faecalis 6 was 16 mg/l. When tested singly E. coli 9 and B. fragilis 1 were both killed by ampicillin at a concentration of 4 mg/l in combination with 1 mg/l sulbactam. When both strains were associated, the MBC for B. fragilis 1 rose to > 256 mg/l. Results obtained indicate that the behaviour of bacteria as determined in pure cultures is not necessarily identical with the antibiotic susceptibility present in mixed cultures. It was shown that, besides beta-lactamase production by involved bacteria, other factors contribute to the alteration of bacterial susceptibility in mixed cultures. Synergistic and antagonistic effects between associated organisms were observed. For example, it was found that two moderately sensitive bacterial strains were resistant in mixed culture.

Efficacy of sulbactam in an in vitro model of mixed aerobic/anaerobic infections

Bacterial interactions in mixed infections may interfere with antimicrobial therapy. The in-vitro efficacy of ampicillin alone, combination sulbactam/ampicillin, and metronidazole was studied. Strains of Bacteroides fragilis, Escherichia coli, and Enterococcus faecalis, alone and in association, were tested by means of a broth dilution method. Minimal bactericidal concentrations (MBC) of ampicillin for B. fragilis 74 in association with E. coli 68 were up to 16-fold higher than for B. fragilis 74 alone (256 compared to 16 mg/l), but only 2-fold higher for sulbactam (5 mg/l)/ampicillin (0.5 and 0.25 g/l). Association of B. fragilis 45 and E. faecalis 186 increased ampicillin MBC of E. faecalis 186 from 2 to 16 mg/l, but the combination sulbactam/ampicillin restored activity of ampicillin. In association with E. faecalis, metronidazole MBCs of B. fragilis increased up to 64-fold. Strains of E. faecalis and E. coli were able to destroy 10 mg/l metronidazole within 8 to 20 h. The present experiments demonstrated effectiveness of sulbactam/ampicillin to inhibit beta-lactamases of associated pathogens. Destruction of metronidazole by E. faecalis lends additional support to the use of the combination in aerobic/anaerobic infections including E. faecalis.

Disseminated intravascular coagulation in Fusobacterium necrophorum septicemia

A previously healthy 42-year-old man developed, after a neglected tonsillitis, a severe Fusobacterium necrophorum septicemia with disseminated intravascular coagulation. Peripheral, painful, cyanotic and gangrenous lesions appeared on toes, external ears and nose tip. The patient survived. Consumption coagulopathy associated with tonsillitis should suggest F. necrophorum infection. Growth of these bacteria in blood cultures is slow and confirmation of the infection may thus be delayed.