Bacteriologic analysis of infected dog and cat bites. Emergency Medicine Animal Bite Infection Study Group

BACKGROUND AND METHODS

To define better the bacteria responsible for infections of dog and cat bites, we conducted a prospective study at 18 emergency departments. To be eligible for enrollment, patients had to meet one of three major criteria for infection of a bite wound (fever, abscess, and lymphangitis) or four of five minor criteria (wound-associated erythema, tenderness at the wound site, swelling at the site, purulent drainage, and leukocytosis). Wound specimens were cultured for aerobic and anaerobic bacteria at a research microbiology laboratory and, in some cases, at local hospital laboratories.

RESULTS

The infected wounds of 50 patients with dog bites and 57 patients with cat bites yielded a median of 5 bacterial isolates per culture (range, 0 to 16) at the reference laboratory. Significantly more isolates grew at the reference laboratory than at the local laboratories (median, 1; range, 0 to 5; P<0.001). Aerobes and anaerobes were isolated from 56 percent of the wounds, aerobes alone from 36 percent, and anaerobes alone from 1 percent; 7 percent of cultures had no growth. Pasteurella species were the most frequent isolates from both dog bites (50 percent) and cat bites (75 percent). Pasteurella canis was the most common isolate of dog bites, and Past. multocida subspecies multocida and septica were the most common isolates of cat bites. Other common aerobes included streptococci, staphylococci, moraxella, and neisseria. Common anaerobes included fusobacterium, bacteroides, porphyromonas, and prevotella. Isolates not previously identified as human pathogens included Reimerella anatipestifer from two cat bites and Bacteroides tectum, Prevotella heparinolytica, and several porphyromonas species from dog and cat bites. Erysipelothrix rhusiopathiae was isolated from two cat bites. Patients were most often treated with a combination of a beta-lactam antibiotic and a beta-lactamase inhibitor, which, on the basis of the microbiologic findings, was appropriate therapy.

CONCLUSIONS

Infected dog and cat bites have a complex microbiologic mix that usually includes pasteurella species but may also include many other organisms not routinely identified by clinical microbiology laboratories and not previously recognized as bite-wound pathogens.

Activities of HMR 3004 (RU 64004) and HMR 3647 (RU 66647) compared to those of erythromycin, azithromycin, clarithromycin, roxithromycin, and eight other antimicrobial agents against unusual aerobic and anaerobic human and animal bite pathogens isolated from skin and soft tissue infections in humans

The activities of HMR 3004 and HMR 3647 and comparator agents, especially macrolides, were determined by the agar dilution method against 262 aerobic and 120 anaerobic strains isolated from skin and soft tissue infections associated with human and animal bite wounds. HMR 3004 and HMR 3647 were active against almost all aerobic and fastidious facultative isolates (MIC at which 90% of the isolates are inhibited [MIC90], < or = 0.5 and 1 microg/ml, respectively) and against all anaerobes [Bacteroides tectum, Porphyromonas macacae (salivosa), Prevotella heparinolytica, Porphyromonas sp., Prevotella sp., and peptostreptococci] at < or = 0.25 and < or = 0.5 microg/ml, respectively, except Fusobacterium nucleatum (HMR 3004, MIC90 = 16 microg/ml; HMR 3647, MIC90 = 8 microg/ml) and other Fusobacterium species (MIC90, 1 and 2 microg/ml, respectively). In general, HMR 3004 and HMR 3647 were more active than any of the macrolides tested. Azithromycin was more active than clarithromycin against all Pasteurella species, including Pasteurella multocida subsp. multocida, Eikenella corrodens, and Fusobacterium species, while clarithromycin was more active than azithromycin against Corynebacterium species, Weeksella zoohelcum, B. tectum, and P. heparinolytica.

Trovafloxacin compared with levofloxacin, ofloxacin, ciprofloxacin, azithromycin and clarithromycin against unusual aerobic and anaerobic human and animal bite-wound pathogens

The activity of trovafloxacin and five other oral agents against 250 aerobic and 137 anaerobic strains isolated from human and animal bite wounds was determined by an agar dilution method. Trovafloxacin was active against all aerobic and fastidious facultative isolates at < or = 0.5 mg/L and all anaerobes at < or = 2 mg/L (Bacteroides tectum, Porphyromonas salivosa and Prevotella heparinolytica, < or = 0.25 mg/L; Porphyromonas spp., < or = 0.5 mg/L; Prevotella spp. and peptostreptococci, < or = 2.0 mg/L), except Fusobacterium nucleatum and other fusobacteria (MIC90 < or = 4 mg/L). Levofloxacin was generally one to two dilutions more active than ofloxacin, while ciprofloxacin was active against aerobes (MIC < or = 1 mg/L) but less active against anaerobic strains (MIC90 < or = 16 mg/L).

Evaluation of the RapID CB Plus system for identification of Corynebacterium species and other gram-positive rods

Due to the difficulty of identifying Corynebacterium spp. with standard methods, we compared them with the RapID CB Plus system (Remel, Lenexa, Kans. [formerly Innovative Diagnostic Systems, Norcross, Ga.]), which consists of 4 carbohydrate and 14 preformed enzyme tests, for the identification of 98 clinical isolates of Corynebacterium sp., other coryneforms, Listeria monocytogenes, and 17 ATCC strains. Forty (95%) of 42 strains of Corynebacterium spp. were accurately identified to the species level by the RapID CB Plus system, and two additional strains of C. striatum were identified with one additional conventional test for lipid requirement. Twenty-seven (75%) of the 36 coryneform strains tested were identified correctly to the species level. However, three of four strains of Brevibacterium sp. and all seven of the L. monocytogenes strains were identified to the genus level only. Actinomyces strains had variable results, and the one strain of Arcanobacterium haemolyticum tested was not identified. Overall, the RapID CB Plus system compared favorably with the conventional methods, was easy to inoculate and interpret, and is promising as a new method for identification of gram-positive bacilli.

Growth characteristics and a novel method for identification (the WEE-TAB system) of Porphyromonas species isolated from infected dog and cat bite wounds in humans

Thirty-nine clinical isolates of Porphyromonas species recovered from infected cat and dog bite wounds in humans and eight American Type Culture Collection and National Collection of Type Cultures type strains were characterized by using the API ZYM system, the RapID ANA II system, and conventional biochemical methods. Growth characteristics on various agar media were compared. All strains grew on brucella blood agar supplemented with vitamin K1 and hemin and on brucella laked blood agar supplemented with vitamin K1 and hemin. In contrast, only 34% of strains grew on unsupplemented brucella blood agar, 62% grew on Columbia blood agar, and 70% grew on tryptic soy blood agar (the last three media did not contain vitamin K1 or hemin). The ability of the single-tube, triple-substrate WEE-TAB system to detect the preformed enzymes N-acetyl-beta-D-glucosaminidase, alpha-D-galactosidase, beta-D-galactosidase, alpha-fucosidase, trypsin-like activity, and chymotrypsin was evaluated. The WEE-TAB test results were easy to interpret; the WEE-TAB tests were more sensitive than the comparable tests with the API ZYM and RapID ANA II systems for the detection of alpha-D-galactosidase, beta-D-galactosidase, trypsin, and chymotrypsin, and the WEE-TAB tests accurately identified Porphyromonas species.

Comparative in vitro activities of trovafloxacin (CP-99,219) against 221 aerobic and 217 anaerobic bacteria isolated from patients with intra-abdominal infections

Four hundred thirty-eight bacteria cultured from specimens of patients with serious intra-abdominal infections were tested by agar dilution against trovafloxacin and other quinolones and antimicrobial agents. Trovafloxacin inhibited 435 strains (99.3%) at < or =2 microg/ml. All the quinolones had similar activities against Enterobacteriaceae and Pseudomonas sp., but trovafloxacin showed superior activities against streptococci, enterococci, and anaerobic organisms. Because of its excellent in vitro activities against diverse bacteria, trovafloxacin has potential use as a single agent for polymicrobial infections.

Evaluation of a novel specimen transport system (Venturi Transystem) for anaerobic bacteria

The Venturi Transystem (Copan Diagnostics, Corona, CA), with and without charcoal, is designed for transport of clinical specimens. It was evaluated for its ability to maintain the viability of pure cultures of selected anaerobic bacteria. Results indicated that the system supported survival of test strains within the time frame that most clinical specimens require to reach the clinical laboratory.

Use of polymerase chain reaction fingerprinting to compare clinical isolates of Bacteroides fragilis and Bacteroides thetaiotaomicron from Germany and the United States

Accurate identification of Bacteroides species is often problematic. Therefore, we used a polymerase chain reaction (PCR) fingerprinting technique with either a single nonspecific primer derived from tDNA intergenic spacer or a single primer that anneals to mini- and microsatellite DNA sequences to compare 34 clinical isolates of B. fragilis and 21 clinical isolates of B. thetaiotaomicron from Southern California with 32 clinical isolates of B. fragilis and 10 isolates of B. thetaiotaomicron from Germany. All German B. fragilis isolates (32 of 32) formed one PCR fingerprint group that matched the PCR profile of the B, fragilis reference strain ATCC (American Type Culture Collection) 25285, representative of DNA homology group I. In contrast, the isolates from Southern California formed two PCR fingerprint groups. Although most of these strains (29 of 34) also matched B. fragilis ATCC 25285, some strains (4 of 34) matched the DNA homology group II reference strain VPI (Virginia Polytechnic Institute) 2393. One of the 34 strains showed a unique profile. German B. thetaiotaomicron strains (10 of 10) formed one PCR fingerprint group, matching the reference strain B. thetaiotaomicron ATCC 29742, whereas the B. thetaiotaomicron isolates from Southern California showed heterogenous profiles.

Bilophila wadsworthia clinical isolates compared by polymerase chain reaction fingerprinting

Bilophila wadsworthia isolates recovered from a right-ear cholesteatoma and brain abscess of the same patient were analyzed by means of polymerase chain reaction (PCR) fingerprinting with single primers (T3B and M13 core) to ascertain if they originated from the same clone. Their PCR fingerprint profiles were compared with those of three additional B. wadsworthia clinical isolates and the type strain (ATCC 49260). The two isolates from the same patient produced PCR fingerprint profiles identical to each other, regardless of which primer was used. All isolates' PCR fingerprint profiles, with use of either the T3B or M13 core primer, shared some major and minor bands. However, differences in additional major and minor bands distinguished each of the additional isolates, suggesting that there are different subgroups of B. wadsworthia.

In vitro activity of Bay 12-8039, a new 8-methoxyquinolone, compared to the activities of 11 other oral antimicrobial agents against 390 aerobic and anaerobic bacteria isolated from human and animal bite wound skin and soft tissue infections in humans

The in vitro activity of Bay 12-8039, a new oral 8-methoxyquinolone, was compared to the activities of 11 other oral antimicrobial agents (ciprofloxacin, levofloxacin, ofloxacin, sparfloxacin, azithromycin, clarithromycin, amoxicillin clavulanate, penicillin, cefuroxime, cefpodoxime, and doxycycline) against 250 aerobic and 140 anaerobic bacteria recently isolated from animal and human bite wound infections. Bay 12-8039 was active against all aerobic isolates, both gram-positive and gram-negative isolates, at < or = 1.0 microg/ml (MICs at which 90% of isolates are inhibited [MIC90s < or = 0.25 microg/ml) and was active against most anaerobes at < or = 0.5 microg/ml; the exceptions were Fusobacterium nucleatum and other Fusobacterium species (MIC90s, > or = 4.0 microg/ml) and one strain of Prevotella loeschii (MICs, 2.0 microg/ml). In comparison, the other quinolones tested had similar in vitro activities against the aerobic strains but were less active against the anaerobes, including peptostreptococci, Porphyromonas species, and Prevotella species. The fusobacteria were relatively resistant to all the antimicrobial agents tested except penicillin G (one penicillinase-producing strain of F. nucleatum was found) and amoxicillin clavulanate.

Comparative in vitro activities of DU-6859a, levofloxacin, ofloxacin, sparfloxacin, and ciprofloxacin against 387 aerobic and anaerobic bite wound isolates

The activities of DU-6859a, levofloxacin, ofloxacin, sparfloxacin, and ciprofloxacin against bite wound isolates were determined by the agar dilution method. DU-6859a was the most active compound (MICs, < or = 0.125 microg/ml) against all Pasteurella species, Staphylococcus aureus, and streptococci; anaerobes were susceptible to < or = 0.5 microg/ml, except fusobacteria, which were susceptible to < or = 2 microg/ml. Against aerobes, levofloxacin was more active than ofloxacin (MIC at which 90% of isolates are inhibited [MIC90], < or = 1.0 microg/ml for both) and sparfloxacin and ciprofloxacin were also active (MIC90s, < or = 0.25 and < 1 microg/ml, respectively).

Characterization of saccharolytic Bacteroides and Prevotella isolates from infected dog and cat bite wounds in humans

Saccharolytic, nonpigmented, anaerobic gram-negative rods isolated from infected dog and cat bite wounds in humans have been poorly characterized, and most are not included in the databases of kits used for anaerobic identification; thus, they are problematic for clinical laboratories to identify. Fifty strains isolated from such wounds were characterized with commercial kits for preformed-enzyme detection, carbohydrate fermentation, and other biochemical tests. PCR fingerprinting was performed on these strains to further characterize subgroups within these species. Bacteroides tectum is a frequent isolate in bite wounds and resembles Prevotella bivia in colony morphology and saccharolytic activity, except that it grows in 20% bile and hydrolyzes esculin. Profile numbers generated by various kits associate B. tectum with P. bivia, Prevotella oralis group, or Prevotella melaninogenica. PCR fingerprinting identified at least four subgroups and confirmed the heterogeneous nature of this species. Prevotella heparinolytica was also frequently isolated from these bite wounds. It produces indole and generates a profile number in preformed-enzyme kits that is usually associated with Bacteroides uniformis. However, it is bile sensitive and quite distinct from the Bacteroides fragilis group of anaerobes. The PCR fingerprint profiles generated by strains of P. heparinolytica were very similar to that of the type strain and to each other. Prevotella zoogleoformans, occasionally isolated from dog and cat bite wounds in humans, resembles P. heparinolytica except for a negative indole test. Clinical laboratories should be aware of the characteristics of these animal species when identifying isolates from animal bite wounds in humans.

Frequency of isolation of Porphyromonas species from infected dog and cat bite wounds in humans and their characterization by biochemical tests and arbitrarily primed-polymerase chain reaction fingerprinting

We isolated 40 strains of Porphyromonas (formerly Bacteroides) species from 29 of 102 cat and dog bite wounds in humans. P. salivosa, P. gingivalis, and P. canoris were the most frequent isolates. A comparison of the RapID ANA II system (Innovative Diagnostic Systems, Norcross, GA), An-IDENT panels (bioMérieux, St. Louis), and API ZYM strips (bioMérieux) showed that the latter kit best characterized these isolates because it included tests for trypsin and chymotrypsin activity; however, the tests for glycosidase activity in this kit were less sensitive than were those in the other kits. None of the biochemical systems was able to identify all species. Arbitrarily primed-polymerase chain reaction fingerprinting with a nonspecific single primer, T3B, yielded distinct profiles for type strains and for the clinical isolates, suggesting that some of the isolates represented previously undescribed species. Growth of these species took > or = 5 days; therefore, laboratories should incubate anaerobic plates from bite wound cultures for > or = 7 days to assure isolation of these common pathogens.

Characterization of indole-negative Bacteroides fragilis group species with use of polymerase chain reaction fingerprinting and resistance profiles

Biochemical tests alone do not adequately differentiate the various Bacteroides species, groups, and antimicrobial-resistant variants. Consequently, we used a polymerase chain reaction (PCR) fingerprinting technique, with either a single nonspecific primer derived from the t-DNA intergenic spacer region (T3B) or a single primer that anneals to minisatellite DNA sequences (M13 core), to identify and characterize 58 clinical isolates of Bacteroides fragilis group species (B. fragilis, B. distasonis, and B. caccae). In addition to species- and subspecies-specific differences, 4 strains of B. fragilis, 1 of B. distasonis, and 3 of B. caccae that showed increased resistance to imipenem, ampicillin, and ampicillin/sulbactam also produced unique PCR fingerprint profiles. Analysis by the clinical source of isolation (i.e. blood or intraabdominal, skin, or soft-tissue infection) indicated that no particular PCR fingerprint type was associated with greater pathogenicity of any individual clinical source. The PCR fingerprinting technique proves to be a useful tool for species identification and taxonomic studies, as well as for epidemiological studies of Bacteroides species.

Comparison of Etest to broth microdilution method for testing Streptococcus pneumoniae susceptibility to levofloxacin and three macrolides

When the Etest was compared to broth microdilution for susceptibility testing of Streptococcus pneumoniae, levofloxacin, erythromycin, and penicillin results correlated for both methods; azithromycin and clarithromycin showed discrepancies of > or = 2 dilutions for 95.8% and 31.5% of the isolates, respectively. Levofloxacin was active against 141 of 142 isolates (< or = 2.0 micrograms/ml), making it a potentially useful new fluoroquinolone.

Comparative in-vitro activity of cefoperazone/sulbactam and 11 other agents against multidrug resistant Bacteroides fragilis group species

The activity of cefoperazone/sulbactam was compared with eleven other antimicrobial agents against 91 strains of the Bacteroides fragilis group known to be resistant to clindamycin and/or beta-lactam agents. Sulbactam alone possessed moderate activity against most strains and improved the activity of cefoperazone and ampicillin. Bacteroides distasonis strains were more resistant than other species. There was no correlation between resistance of an isolate to either clindamycin or cefoxitin with resistance to cefoperazone/sulbactam.

Diabetic foot infections. Bacteriology and activity of 10 oral antimicrobial agents against bacteria isolated from consecutive cases

OBJECTIVE

To study the relative frequency of bacterial isolates cultured from community-acquired foot infections and assess their comparative in vitro susceptibility to sparfloxacin, levofloxacin, and eight other commonly used oral antimicrobial agents.

RESEARCH DESIGN AND METHODS

This is a prospective study in which the infected wounds of 25 consecutive diabetic patients seen by one of the authors were cultured as they entered the hospital. Isolates were stored and tested for susceptibility to 10 oral antimicrobial agents using the agar dilution method.

RESULTS

Staphylococcus aurcus was the most common isolate (76% of patients), including methicillin-resistant S. aurcus (MRSA) in 5 of 25 (20%) patient wounds. Streptococci, enterococci, Enterobacteriaceae, and anaerobes were also present in > or = 40% of patient wounds. Sparfloxacin and levofloxacin were the most active agents tested with activity against > or = 88% of isolates. Isolates resistant to sparfloxacin and levofloxacin included MRSA, enterococci, and some anaerobes. When analyzed by prior exposure to antibiotics, patients who had previously received oral antibiotics were more likely to have MRSA, enterococci, and Pseudomonas aeruginosa isolated and less likely to have Enterobacteriaceae and anaerobes isolated from their wounds.

CONCLUSIONS

MRSA and enterococci are now a common cause of diabetic foot infections, and the increased prevalence may be due to antimicrobial use. These wounds may require use of combined antimicrobial therapy for initial outpatient management. The new fluoroquinolones, sparfloxacin and levofloxacin, were the most active oral agents tested.

Identification and antimicrobial resistance patterns of clinical isolates of Clostridium clostridioforme, Clostridium innocuum, and Clostridium ramosum compared with those of clinical isolates of Clostridium perfringens

Clostridium ramosum, C. innocuum, and C. clostridioforme are frequently isolated from clinical specimens including blood. Because of Gram stain variability, a lack of spores, and atypical colonial morphology, identification of these species is often difficult. Three anaerobe identification kits were evaluated for their abilities to identify these species. For comparison, 11 strains of C. perfringens were evaluated in parallel. By using profile numbers and codebooks, the correct genus and species were identified, as follows: with the RapID ANA II kit, 100% (20 of 20) of C. ramosum isolates, 24% (5 of 21) of C. innocuum isolates, and 50% (10 of 20) of C. clostridioforme isolates; with the AnIDent kit, 60% (12 of 20) of C. ramosum isolates, 28% (6 of 21) of C. innocuum isolates, and 90% (18 of 20) of C. clostridioforme isolates; with the ATB32A kit, 70% (14 of 20) of C. ramosum isolates, 0% (0 of 21) of C. innocuum isolates, and 40% (8 of 20) of C. clostridioforme isolates. Profile numbers that overlapped several species were obtained as follows: with the RapID ANA II kit, 0% of C. ramosum isolates, 76% of C. innocuum isolates, and 40% of C. clostridioforme isolates; with the AnIDent kit 40% of C. ramosum isolates, 62% of C. innocuum isolates, and 5% of C. clostridioforme isolates; with the ATB32A kit, 15% of C. ramosum isolates, 52% of C. innocuum isolates, and 25% of C. clostridioforme isolates. One strain of C. innocuum was misidentified by the AnIDent kit, and the remainder yielded profile numbers that were not listed in the codebooks. The MICs of 11 antimicrobial agents including penicillin G, metronidazole, clindamycin, cefoxitin, cefotetan, imipenem, meropenem, amoxicillin-clavulanate, ampicillin-sulbactam, piperacillin-tazobactam, and vancomycin were determined by the agar dilution method. All C. perfringens strains were susceptible to all antimicrobial agents tested. Various levels of resistance to cefoxitin, cefotetan, and penicillin G were noted with C. ramosum, C. clostridioforme, and C. innocuum. In addition, resistance to clindamycin was noted with C. ramosum (5%) and C. innocuum (10%). Most strains of C. innocuum were only moderately susceptible to vancomycin (MIC at which 90% of strains are inhibited, 4 micrograms/ml).

Survival of anaerobic bacteria in various thioglycolate and chopped meat broth formulations

Three commercially available formulations of thioglycolate broth and of chopped meat broth were evaluated for their abilities to maintain the viabilities of 32 strains of anaerobic bacteria during a period of 8 weeks. While thioglycolate broth supported the initial (48-h) growth of all strains tested, approximately half of the strains died off within 4 weeks. Chopped meat broths maintained the viabilities of almost all cultures during the test period.

Simian bites and bacterial infection

Three patients with simian bites and resultant infection are described. The bacteriology of the wounds was diverse and included alpha-hemolytic streptococci and other streptococci in all wounds, enterococci, Staphylococcus epidermidis, and Enterobacteriaceae. A literature review revealed brief mentions of 132 cases of simian bites in some of which Bacteroides species, Fusobacterium species, and Eikenella corrodens were isolated. Infection, despite antimicrobial therapy, and complications, such as osteomyelitis and flexion contractures, occurred frequently.

Activity of ampicillin/sulbactam, ticarcillin/clavulanate, clarithromycin, and eleven other antimicrobial agents against anaerobic bacteria isolated from infections in children

The activity of 14 antimicrobial agents against 253 clinical isolates of anaerobic bacteria from pediatric infections was assessed by the agar dilution method. Fifty-eight percent of the isolates were from intraabdominal sites. The drugs tested were ampicillin/sulbactam, ticarcillin/clavulanate, ampicillin, sulbactam, piperacillin, cefoxitin, cefotaxime, cefoperazone/sulbactam, clarithromycin, azithromycin, erythromycin, clindamycin, metronidazole, and chloramphenicol. Ticarcillin/clavulanate was active against all isolates. Clarithromycin was the most active macrolide; combination of this agent with its 14-hydroxy metabolite did not result in synergy. Sixty-two percent of Bacteroides fragilis group isolates, 13% of B. fragilis isolates, and 22% of peptostreptococcal isolates were resistant to clindamycin at a concentration of 4 micrograms/mL. The distribution of these strains in clinical specimens and the patterns of antimicrobial susceptibility documented were different from the findings for isolates from adults in the Los Angeles area.

Comparative in vitro activities of azithromycin, Bay y 3118, levofloxacin, sparfloxacin, and 11 other oral antimicrobial agents against 194 aerobic and anaerobic bite wound isolates

The activities of sparfloxacin, levofloxacin, Bay y 3118, azithromycin, cefprozil, loracarbef, and nine other oral antimicrobial agents against 194 aerobic and anaerobic clinical bite wound isolates were determined by the agar dilution method. Sparfloxacin, levofloxacin, and Bay y 3118 were active against all aerobic isolates (MICs at which 90% of the isolates are inhibited [MIC90], < or = 1.0 microgram/ml for sparfloxacin and levofloxacin and 0.1 microgram/ml for Bay y 3118) and many anaerobic isolates, with the exception of the fusobacteria. Azithromycin was more active than erythromycin by 1 to 2 dilutions against many aerobes, including Pasteurella multocida and Eikenella corrodens, and by 2 to 4 dilutions against anaerobic isolates. Cefprozil was more active (MIC90, < or = 1 microgram/ml) than loracarbef (MIC90, < or = 4 micrograms/ml) against aerobic gram-positive isolates, but both had poor activity (MIC90, > or = 16 micrograms/ml) against peptostreptococci. Both cefprozil and loracarbef had MIC90s of < or = 0.5 micrograms/ml against P. multocida.

Fatal sepsis due to a beta-lactamase-producing strain of Fusobacterium nucleatum subspecies polymorphum

A patient with Waldenström's macroglobulinemia was treated empirically with imipenem for sepsis related to oropharyngeal infection and responded within 24 hours. When blood cultures yielded Streptococcus agalactiae, the regimen was changed to ampicillin and gentamicin. The patient's condition rapidly deteriorated, and she died 3 days later. After her death, a strain of Fusobacterium nucleatum subspecies polymorphum producing beta-lactamase (PEN-Y; group 2a) was isolated from blood cultures. A literature review revealed increasingly frequent isolation of beta-lactamase-producing strains of F. nucleatum. Thus strains of F. nucleatum isolated from blood and other specimens from patients with serious infections should be tested for beta-lactamase production.