Carolyn N. Baker

Helicobacter cinaedi-associated bacteremia and cellulitis in immunocompromised patients.

Although initially associated with gastroenteritis in homosexual men [1-4], Helicobacter cinaedi was also isolated from asymptomatic [1, 3, 4] and bacteremic [5-7] homosexual men. These organisms are also associated with illness outside the homosexual population; Vandamme and colleagues [8] described three bacteremic patients and two children with fecal isolates. A retrospective epidemiologic study was done to define the clinical spectrum of illness and epidemiologic risk factors associated with H. cinaedi infection in the United States. We also looked at laboratory methods used to recover H. cinaedi. Patients were identified from H. cinaedi isolates received at the Centers for Disease Control and Prevention (CDC) between January 1982 and August 1990. Case Report A 32-year-old man developed red-copper-colored blotches on his left ankle 6 weeks before admission; these spread to his right ankle, up the legs, to the arms, chest, and face. At the time of onset, the patient reported fever but no gastrointestinal symptoms. He was given cephalexin, 500 mg four times a day, for sinusitis; he noted that the rash worsened. Three weeks before he was hospitalized, the patient received oral ciprofloxacin for 2 weeks; the rash resolved. The rash reappeared, and the patient presented with chills and fever (a temperature of 39.4 C), nausea, arthralgias, and the maculopapular skin eruption. At admission, blood cultures were done, and he was treated empirically with cefotaxime and tobramycin. His leukocyte count at admission was 7.8 109/L, with a differential of 73 segmented neutrophils, 18 lymphocytes, and 8 monocytes. Platelets were noted as adequate. His medical history included seropositivity to human immunodeficiency virus (HIV) and transient immune thrombocytopenia (platelet count, 35 109/L); a platelet count of 192 109/L was noted 4 months before admission. The patient stated that the rash first appeared approximately 24 hours after using a whirlpool spa. He did not recall eating raw dairy products, eggs, seafood, or other meats. The patient reported recreational exposure to sea and lake water but did not recall drinking untreated surface water. He traveled within the United States and Europe and reported having homosexual contact in the month before onset of illness. After positive blood cultures were identified, the patient was given empiric ciprofloxacin, 250 mg twice a day for 14 days. The cellulitis cleared, and the patient was discharged. The cellulitis recurred 11 weeks later; the patient was rehospitalized and treated with cefotaxime and ciprofloxacin. Two blood cultures obtained at the time of the second admission again yielded H. cinaedi. The patients leukocyte count was now 6.8 109/L. The rash again cleared. The patient reported three additional recurrences. After zidovudine therapy was initiated, no further recurrence of cellulitis was noted. Results Patients with H. cinaedi infection ranged in age from 24 to 84 years (mean, 44 years); 83% were men. Patients resided in 14 different states (1, Arizona; 1, Colorado; 6, California; 1, Georgia; 1, Illinois; 1, Kansas; 1, Michigan; 2, Missouri; 2, Nebraska; 1, New Mexico; 2, Ohio; 1, Tennessee; 3, Texas; and 1, Wisconsin). Isolation of the organism occurred from 1982 to 1990 (2 in 1982, 2 in 1984, 3 in 1985, 2 in 1986, 3 in 1987, 5 in 1988, 2 in 1989, and 4 in 1990) without seasonal clustering. No one died of this infection. Appendix Table 2 shows the clinical features of 21 patients (information on 5 patients was provided after a review of medical records by the local health department). Most patients had a sudden onset of fever (range, 37.8 to 40.0 C; mean, 38.9 C). Nine bacteremic patients (41%) had both fever and a distinctive cellulitis that was described as atypical, appearing red-brown or copper without noticeable warmth. Underlying immunosuppressive illness was reported for 14 of 21 patients; other underlying conditions, previously associated with systemic Campylobacter infections, were reported infrequently. Appendix Table 1. Characteristics of Patients with Helicobacter cinaedi Infection Information regarding potential exposures in the 4 weeks before onset was available for 15 patients. The most frequent exposures of interest were contact with or consumption of untreated surface water (three patients) and contact with animals (nine patients). Four patients reported out-of-state travel in the 4 weeks before onset: one to Mexico, one to Europe, one to Hawaii, and one to Colorado on a camping trip. All blood isolates of H. cinaedi were recovered after detection by an automated blood culture instrument; 21 of 22 isolates were recovered from the aerobic bottle; 1 isolate was also detected in the anaerobic bottle, and 1 isolate was detected solely in the anaerobic bottle. Most isolates were detected after 5 or more days of incubation by slightly elevated growth indexes (generally between 40 and 80; mean, 57). In general, organisms were not seen on initial Gram staining of the blood culture material but were detected by dark-field or acridine orange staining. Only 9 (41%) of 22 blood isolates were recovered by the primary hospital laboratory; all other isolates were cultured by reference laboratories. In contrast to Campylobacter jejuni, H. cinaedi is not susceptible to erythromycin in vitro (Table 1). In general, tetracyclines and aminoglycosides seem most effective in vitro. Table 1. Antimicrobial Susceptibility of 22 Strains of Helicobacter cinaedi Associated with Human Clinical Illness* Discussion Our findings indicate that H. cinaedi is associated with a new syndrome, consisting of fever, bacteremia, and recurrent cellulitis. Most patients had signs of systemic infection, including leukocytosis, and were often thrombocytopenic. Although H. cinaedi isolates were recovered primarily from immunocompromised patients and from those with chronic alcoholism, we also documented infections in three nonimmunocompromised men and in women (both with and without HIV infection). Thus, the patient group affected by H. cinaedi is larger than originally thought. We did not find distinctive risk factors for acquisition of H. cinaedi by interviewing a subset of patients; however, our review may have been hampered by the time between illness and interview. Our data suggest that contact with animals or exposure to untreated surface water are possible sources of infection. Currently, H. cinaedi has been isolated only from humans and gerbils [9], but no patients reported having contact with gerbils. Many antimicrobial therapies were used to treat patients with H. cinaedi infection. From our series, it appears that treatment with a penicillin, tetracycline, or aminoglycoside may be more effective than treatment with cephalosporins, erythromycin, or ciprofloxacin. In addition, prolonged therapies (2 to 6 weeks) may be more effective than short-term therapies ( 10 days; data not shown). The apparent effectiveness of tetracycline or aminoglycosides agrees with in vitro antimicrobial susceptibility data. Although two reports suggest treating H. cinaedi with ciprofloxacin [10, 11], infection reappeared in two patients treated with this agent, and our in vitro data indicate that their isolates and two additional isolates were resistant (minimal inhibitory concentration > 8 g/mL). This finding suggests that ciprofloxacin should be used with caution. However, we were unable to obtain isolates before and after treatment, so we cannot determine whether resistance to ciprofloxacin developed as a result of therapy or existed before therapy was begun. Our susceptibility data agree with previously published data [12], with one exception: Fifty percent of our strains were resistant to cephalothin. Laboratory diagnosis of H. cinaedi infection is unlikely using blood culture procedures that rely on visual detection because it grows slowly and the growth is difficult to see; all blood isolates were recovered using an automated system. We therefore suggest examining blood cultures that develop slightly elevated growth indexes in an automated system using acridine orange staining, Giemsa staining, or dark-field examination before discarding a specimen as negative. In general, specialized culture techniques and prolonged incubation (7 days) must be used to isolate these organisms: Growth is enhanced by the presence of hydrogen gas in a microaerobic atmosphere and incubation on rich, nonselective media (blood or chocolate agar) at 37 C. Techniques that would probably isolate H. cinaedi from stool specimens include filtration onto nonselective media or inoculation of appropriate selective media and incubation at 37 C in a hydrogen-containing atmosphere for 3 to 4 days. A retrospective review of patients with H. cinaedi infection suggests a syndrome of recurrent febrile bacteremia, which may be accompanied by cellulitis in immunocompromised patients. Helicobacter cinaedi infection should be considered in an immunocompromised or thrombocytopenic patient with fever and cellulitis. Specific antimicrobial therapy may be needed to prevent recurrence. The slow growth and fastidious culture requirements of this organism indicate that it may be currently under-recognized.

Infection caused by Francisella philomiragia (formerly Yersinia philomiragia). A newly recognized human pathogen

We evaluated the clinical characteristics of patients with Francisella philomiragia (formerly Yersinia philomiragia) isolated from normally sterile sites. Isolates from 14 patients were received by the Centers for Disease Control between 1975 and 1987: 9 were from blood; 2 from lung biopsies; and 1 each from pleural, peritoneal, and cerebrospinal fluid. Underlying problems included chronic granulomatous disease in 5 patients, near-drowning in 5, and a myeloproliferative disease in 2. All 13 patients for whom records were available had a febrile syndrome compatible with bacterial infection. Pneumonia and fever-bacteremia were the commonest clinical syndromes reported. In 7 cases, F. philomiragia was the only sterile-site isolate, and the clinical syndrome did not resolve without appropriate antibiotics. Familiarity with this organism is important because of its ability to cause serious disease in chronic granulomatous disease and near-drowning patients. Further study may yield new insights into pathogenic and host defense mechanisms.

In Vitro Activity of Antimicrobial Agents on Legionnaires Disease Bacterium

Six isolates of Legionnaires disease bacteria were tested for their susceptibility to 22 antimicrobial agents. The most active agent was rifampin (minimal inhibitory concentration, ≤0.01 μg/ml). On the basis of minimal inhibitory concentration breakpoints that have been used to categorize susceptibility for most of these drugs, the organisms were susceptible to rifampin, cefoxitin, erythromycin, the aminoglycosides, minocycline and doxycycline, chloramphenicol, ampicillin, penicillin G, carbenicillin, colistin, and sulfamethoxazole-trimethoprim (19:1 ratio); sensitive to intermediate in susceptibility to tetracycline, methicillin, cefamandole, cephalothin, and clindamycin; and resistant to vancomycin. More clinical data must be obtained before an optimal therapeutic regimen can be recommended.

Synergism, killing kinetics, and antimicrobial susceptibility of group A and B streptococci.

The susceptibility of 110 group A and 179 group B streptococci to 25 antimicrobics was tested by broth microdilution and agar disk diffusion tests. Representative strains were used in killing kinetics, penicillin-gentamicin synergy, and minimal bactericidal concentration tests. Group A streptococci were more susceptible than group B streptococci to 17 of the 25 antimicrobics tested. Group A and B streptococci were killed at the same rate if the amount of penicillin used was equivalent to their respective penicillin minimal inhibitory concentrations. Synergism was demonstrated for both group A and B streptococci when penicillin was used at concentrations equal to each respective minimal inhibitory concentration and subinhibitory concentration of gentamicin. This synergy could be demonstrated best using minimal bactericidal concentrations obtained by culturing 3- and 6-h cultures from the microdilution checkerboard tests rather than from 24-h subcultures. A greater synergistic effect was achieved by adding penicillin first and then adding gentamicin rather than in the reverse order, or simultaneously.

In vitro antimicrobial activity of cefoperazone, cefotaxime, moxalactam (LY127935), azlocillin, mezlocillin, and other beta-lactam antibiotics against Neisseria gonorrhoeae and Haemophilus influenzae, including beta-lactamase-producing strains.

Minimum inhibitory concentrations and agar disk diffusion tests were determined on clinical isolates of beta-lactamase-positive and beta-lactamase-negative Neisseria gonorrhoeae and Haemophilus influenzae with the newer beta-lactam antibiotics, cefoperazone, cefotaxime, moxalactam (LY127935), azlocillin, mezlocillin, and piperacillin, and with seven older beta-lactam antibiotics. All the drugs were active against beta-lactamase-negative strains of N. gonorrhoeae and H. influenzae. The drug most active against beta-lactamase-positive N. gonorrhoeae was cefotaxime, followed closely by cefoperazone, moxalactam, piperacillin, and mezlocillin. The drugs most active against beta-lactamase-positive strains of H. influenzae were cefotaxime, moxalactam, cefoperazone, and cefamandole.

Effect of calcium and magnesium ions on the susceptibility of Pseudomonas species to tetracycline, gentamicin polymyxin B, and carbenicillin.

The effect of calcium and magnesium on the susceptibility of 13 species of Pseudomonas to tetracycline, gentamicin, polymyxin B, and carbenicillin was measured. The majority of the minimum inhibitory concentrations (MICs) of these antibiotics was increased if these cations were added to the test media. The increases in MICs caused by calcium or magnesium were similar, but the combination of both ions generally caused a greater change than either alone. Although the MIC of polymyxin B was most affected by calcium and magnesium, its interpretive susceptibilities (i.e., whether susceptible or resistant) were least changed. Susceptibility tests on Pseudomonas species probably should be done with Muller-Hinton broth supplemented with physiological concentrations of calcium and magnesium to better approximate the in vivo activity of these antibiotics. When the susceptibility tests were performed with Mueller-Hinton agar, the MICs were slightly less than those obtained with Mueller-Hinton broth supplemented with both cations but greater than those obtained with Mueller-Hinton broth supplemented with individual cations.

Antibiotic Susceptibility of Streptococcus bovis and Other Group D Streptococci Causing Endocarditis

Seventy-four strains of Streptococcus bovis and 35 strains of enterococci (Streptococcus faecalis and its varieties, Streptococcus faecium and Streptococcus durans), most of which were isolated from patients with endocarditis, were tested for their susceptibility to penicillin, ampicillin, erythromycin, cephalothin, vancomycin, methicillin, tetracycline, chloramphenicol, kanamycin, streptomycin, and gentamicin. Minimal inhibitory concentrations (MIC) and minimal bactericidal concentrations (MBC) were determined by a microtiter broth dilution technique. All of these organisms are group D streptococci, but the S. bovis strains are not enterococci. On the basis of both MIC and MBC, the S. bovis strains were much more susceptibile in general to antibiotics then were the enterococcal strains. For the S. bovis strains, the lowest MICs were obtained with penicillin, ampicillin, and erythromycin, and the lowest MBCs with penicillin and ampicillin. Although these antibiotics were also the most active against the enterococci, the MICs and MBCs were much higher than obtained with the S. bovis strains. Gentamicin was the most active aminoglycoside. On the basis of in vitro susceptibility results, the S. bovis strains resemble the viridans streptococci rather than enterococci.

Effect of Temperature on the In Vitro Susceptibility of Staphylococcus aureus to Penicillinase-Resistant Penicillins

Heteroresistant (methicillin-resistant) and nonheteroresistant strains of Staphylococcus aureus were tested for their susceptibility to penicillinase-resistant penicillins at incubation temperatures of 37, 35, and 30 C. Susceptibilities were determined by agar dilution and by the standard Kirby-Bauer agar diffusion tests. Minimal inhibitory concentrations were higher at 35 and 30 C than at 37 C. Heteroresistance could be detected with the Kirby-Bauer test if the incubation temperature was 30 or 35 C instead of 37 C, when tests were performed against methicillin, oxacillin, or nafcillin, because the resistant organisms grew up to the disks even though the susceptible organisms were inhibited. At 37 C, the resistance was detectable with some strains but not with others. When cloxacillin disks were used, the temperature effect was not seen. The incubation temperature did not affect results with nonheteroresistant strains. Therefore, it is recommended that all Kirby-Bauer tests be incubated at a temperature of 35 C to insure detection of methicillin-resistant S. aureus strains. Detection of these strains is of increasing importance because the incidence of infections with these organisms is increasing, particularly in hospitalized patients. Images

The E-Test and Campylobacter jejuni

The E-Test is a recently introduced method for performing antimicrobial susceptibility tests. We compared the E-Test to the broth microdilution test and to the standard agar dilution test by using five antimicrobial agents tested against 55 clinical isolates of Campylobacter jejuni from 11 locations in USA (group 1). Later, we selected 30 strains (group 2), which were more resistant than the original survey isolates. Erythromycin, tetracycline, and ciprofloxacin were tested on both groups of organisms. When the three test methods were compared with each other at +/- 1 log2 dilution, the E-test gave the best overall agreement, with 85% of all strains being within acceptable limits. Category interpretation of erythromycin (drug of choice) results was a problem using current NCCLS guideline breakpoints. For the E-Test and the agar dilution method, 82% of the strains were in the intermediate category; but with the broth microdilution method, only 16.4% of the isolates were interpreted as intermediate. If the susceptible category breakpoint was raised to less than or equal to 2 micrograms/ml, then only 3% of the C. jejuni isolates would be interpreted as intermediate by any of the three methods. Our preference for antimicrobial susceptibility testing of C. jejuni is either E-Test or agar dilution at 42 degrees C for 16 hr.

In vitro susceptibilities of aerotolerant Campylobacter isolates to 22 antimicrobial agents.

We evaluated the in vitro activities of 22 antimicrobial agents against 78 human and animal isolates belonging to two aerotolerant Campylobacter species, C. cryaerophila and C. butzleri, using a broth microdilution technique. An additional 10 antimicrobial agents were included at concentrations found in selective Campylobacter media. Strains of C. cryaerophila belonged to two DNA hybridization groups: DNA hybridization group 1A, which includes the type strain of C. cryaerophila, and DNA hybridization group 1B. The aminoglycosides, fluoroquinolones, and one tetracycline (minocycline) demonstrated the most activity against all DNA hybridization groups (C. cryaerophila DNA groups 1A and 1B and C. butzleri). Most isolates were resistant to cephalosporin antibiotics, with the exception of cefotaxime, and were variably susceptible to trimethoprim-sulfamethoxazole. C. cryaerophila DNA hybridization group 1A isolates were generally susceptible to the tetracyclines, chloramphenicol, nalidixic acid, azithromycin, erythromycin, and roxithromycin and moderately susceptible to clindamycin, trimethoprim-sulfamethoxazole, ampicillin, and ampicillin-sulbactam. The MICs of tetracyclines were higher for C. butzleri and C. cryaerophila DNA hybridization group 1B isolates than for C. cryaerophila DNA hybridization group 1A isolates, but most strains were still susceptible to doxycycline and tetracycline; all isolates were susceptible to minocycline. C. butzleri and C. cryaerophila DNA hybridization group 1B isolates were generally resistant to the macrolide antibiotics (including erythromycin), chloramphenicol, clindamycin, nalidixic acid, ampicillin, and trimethoprim-sulfamethoxazole. Differences in antimicrobial susceptibility between aerotolerant Campylobacter species and more common Campylobacter species, e.g., C. jejuni, suggest that different treatment strategies may be necessary. Strains of all three DNA hybridization groups of aerotolerant Campylobacter isolates were susceptible to colistin, polymyxin B, and rifampin at concentrations commonly used in selective media. These results suggest that primary isolation methods for Campylobacter species may need to be modified to include aerotolerant Campylobacter strains.