Gram-positive anaerobic cocci.

Gram-positive anaerobic cocci (GPAC) are a heterogeneous group of organisms defined by their morphological appearance and their inability to grow in the presence of oxygen; most clinical isolates are identified to species in the genus Peptostreptococcus. GPAC are part of the normal flora of all mucocutaneous surfaces and are often isolated from infections such as deep organ abscesses, obstetric and gynecological sepsis, and intraoral infections. They have been little studied for several reasons, which include an inadequate classification, difficulties with laboratory identification, and the mixed nature of the infections from which they are usually isolated. Nucleic acid studies indicate that the classification is in need of radical revision at the genus level. Several species of Peptostreptococcus have recently been described, but others still await formal recognition. Identification has been based on carbohydrate fermentation tests, but most GPAC are asaccharolytic and use the products of protein degradation for their metabolism; the introduction of commercially available preformed enzyme kits affords a physiologically more appropriate method of identification, which is simple and relatively rapid and can be used in routine diagnostic laboratories. Recent reports have documented the isolation in pure culture of several species, notably Peptostreptococcus magnus, from serious infections. Studies of P. magnus have elucidated several virulence factors which correlate with the site of infection, and reveal some similarities to Staphylococcus aureus. P. micros is a strongly proteolytic species; it is increasingly recognized as an important pathogen in intraoral infections, particularly periodontitis, and mixed anaerobic deep-organ abscesses. Comparison of antibiotic susceptibility patterns reveals major differences between species. Penicillins are the antibiotics of choice, although some strains of P. anaerobius show broad-spectrum beta-lactam resistance.

Peptostreptococcus vaginalis or Peptostreptococcus prevotii? Identification and clinical importance of a new species of Peptostreptococcus.

Peptostreptococcus vaginalis is a recently described species of Gram-positive anaerobic coccus. We report one case in which P. vaginalis was isolated in pure culture from an abscess on the upper arm, and summarise nine further cases where it was isolated in mixed culture from other superficial sites, particularly infected leg ulcers. We suggest that clinical strains of P. vaginalis have probably been described in the past as Peptostreptococcus prevotii, a species which has frequently been reported from clinical surveys of anaerobic infections; their relative importance and appropriate treatment are discussed. Preformed enzyme profiles provide a simple method of identification accessible to routine diagnostic laboratories; when clinically significant isolates of GPAC are isolated in pure growth, they should be identified to the species level by use of preformed enzyme kits.

Do blood cultures need continuous monitoring so that clinical action can be taken outside normal working hours?

Many automated blood culture reading systems monitor bacterial growth 24 hours a day but it is unclear if reacting to prompts indicating bacterial growth outside normal laboratory hours is of clinical benefit. An analysis of 50 blood cultures from 43 patients which had organisms seen on Gram films and had triggered positive out-of-hours showed that examination of the Gram film altered management of seven patients and the results of culture or sensitivity testing altered that of a further four. However, after review, it was felt the clinical outcome would not have been influenced by earlier intervention in any of these patients. We therefore consider that an out-of-hours service for dealing with positive blood cultures is not justified in our hospital. This conclusion may not apply universally, especially in hospitals where potential pathogens show less predictable antimicrobial sensitivity patterns.

A numerical taxonomic study of the gram-positive anaerobic cocci.

Clinical (101) and collection (26) strains of gram-positive anaerobic cocci were examined in conventional tests and pyrolysis mass spectrometry (PMS). Numerical classifications based upon conventional test reaction patterns (CTRPs) and PMS showed 27 and 22 clusters, respectively. Cross-tabulation of cluster membership in the two classifications showed excellent correlation, with the combined classifications showing clear groups corresponding to the currently recognised species Peptostreptococcus anaerobius, P. heliotrinreducens, P. hydrogenalis, P. indolicus, P. lactolyticus, P. magnus, P. micros and Peptococcus niger. Strains of P. prevotii and P. tetradius clustered together in a heterogeneous group of saccharolytic organisms. However, strains previously identified as P. asaccharolyticus were divided into three distinct groups in PMS, two of which differed only in indole-associated pyrolysis products. A further four groups and several single-member clusters were distinct from these species. PMS data supported the validity of identification by pre-formed enzyme profiles and confirmed that Hare group III is synonymous with P. hydrogenalis, Hare group IV with P. magnus, and the "ADH group" with P. vaginalis. There is clearly a need for a taxonomic revision of the genus Peptostreptococcus, which probably encompasses several generic groups.

Antibiotic availability and multiresistant coliforms in a rural Ugandan hospital.

Twenty-seven strains of coliforms (Enterobacteriaceae) isolated at Kisiizi Hospital, Uganda, were tested for their sensitivity to antibiotics. Sixteen of the 18 patient strains were identified as Escherichia coli, but biochemical analysis, serotyping, plasmid profile and antibiogram showed them to be heterogeneous. Resistance was very common to the antibiotics available in the community (ampicillin, chloramphenicol, tetracycline and trimethoprim), but was much less frequent for the agents used only in the hospital (gentamicin, ciprofloxacin and nitrofurantoin). A correlation was noted between the presence of large plasmids (150 kb or larger) and resistance to amoxicillin in patient strains of E. coli. The nine strains of coliform from the water supply were more heterogeneous and less resistant. The availability of antibiotics in the community seems linked to the development of multiresistant coliforms, which in a Ugandan context are very difficult to treat, and even more difficult to prevent.

The clinical importance of gram-positive anaerobic cocci isolated at St Bartholomew's Hospital, London, in 1987.

The clinical importance of the gram-positive anaerobic cocci (GPAC) isolated in 1987 at St Bartholomew's Hospital, London, is assessed. Of about 800 anaerobic isolates, 209 (27%) were GPAC, of which 67 (32%) were from abscesses and 22 (11%) were in pure growth. Four species comprised 77% of the 168 isolates available for study: Peptostreptococcus magnus (55 isolates, 33%), P. micros (23, 14%), P. asaccharolyticus (24, 14%) P. asaccharolyticus (24, 14%) and P. anaerobius (27, 16%). Different species were associated with different sites, from P. magnus (usually skin-associated sites; normally cultured with aerobes, infrequently with other anaerobes), P. asaccharolyticus (distributed widely) and P. anaerobius (usually genitourinary and gastrointestinal; always below the diaphragm) to P. micros (always deep sites with other anaerobes). P. magnus was isolated from 15 abscesses and was obtained in pure culture from 11 specimens, six of them abscesses developing from infected sebaceous cysts. P. micros was usually isolated from soft tissue abscesses, never from the skin, and with a characteristic mixed flora consisting of "Streptococcus milleri" and anaerobic gram-negative rods. P. heliotrinreducens was a rare isolate from similar specimens. P. asaccharolyticus was cultured from a wide variety of sites, typically mixed with both aerobes and anaerobes, and frequently from abscesses. Most isolates of P. anaerobius came from gastrointestinal or female genitourinary specimens, never from above the diaphragm and rarely from the skin; cultures were usually heavily mixed. Isolates of P. vaginalis and the "bGAL" group made up 11% of str ains and were usally cultured from superficial sites, P. vaginalis often from post-operative wound infections with Staphylococcus aureus.(ABSTRACT TRUNCATED AT 250 WORDS)

Audit of antibiotic policy and wound infection in neck surgery.

Neck surgery on 100 consecutive patients in a unit with an established antibiotic policy was studied. An infection rate of 3% was recorded, comparing well with previously published studies. There were no major sequelae in the infected cases. A policy of no perioperative antibiotics for 'clean' surgery for benign disease, cefuroxime for 'clean' surgery for malignant disease and cefuroxime plus metronidazole for 'clean contaminated' surgery is vindicated.

The laboratory identification of gram-positive anaerobic cocci.

A collection of 256 clinical strains and 40 reference strains of gram-positive anaerobic cocci (GPAC) was studied, to characterise the recognised species more fully and to define groups of strains which might correspond to previously undescribed species. The methods used were: gas-liquid chromatography (GLC) for the detection of volatile fatty acids (VFAs); determination of the pre-formed enzyme profile with a commercially available kit, ATB 32A; microscopic appearance; colonial morphology; and antibiotic sensitivity tests. Strains were placed in one of five VFA groups according to their GLC profile; 96% of strains were further assigned to 12 groups by their enzyme profile. There was less than 99% agreement between the two methods. Of 111 clinical strains in the VFA-negative group, 110 gave one of three distinct enzyme profiles corresponding to Peptostreptococcus magnus, P. micros and P. heliotrinreducens. The assignment of strains to groups based on their microscopic appearance and colonial morphology agreed well with groupings according to enzyme profile. Identification of butyrate-producing GPAC was unsatisfactory because it relied heavily on the enzyme profile; testing for indole production was of limited discriminative value. Most strains of P. asaccharolyticus and P. indolicus were very similar in enzyme profile, microscopic appearance and colonial morphology, but a sub-group of P. asaccharolyticus could be distinguished. A further indole-positive group corresponding to Hare group III was also noted. Strains of P. prevotii and P. tetradius were very similar, but easily distinguished from other butyrate-producing GPAC. However, 45% of the butyrate-producing cocci could not be assigned to recognised species; most of these were assigned to one of two new groups, the ADH group and the bGAL group, by their enzyme profile, microscopic appearance and smell. Four strains that produced a terminal VFA peak of isovaleric acid formed a new group designated 'ivoricus'. Reliable features for the identification of P. anaerobius were GLC (all GPAC that produced isocaproic acid were identified as P. anaerobius), enzyme profile and sensitivity to SPS. Two clinical strains that produced caproci acid were identified as Hare group VIII; they were distinguished from Peptococcus niger by their enzyme profile and colonial morphology. A phenotypic classification based on GLC and enzyme profile is presented, with a method for the identification of most strains of GPAC within 48 h of primary isolation.

Effect of ceftazidime and gentamicin on the oropharyngeal and faecal flora of patients with haematological malignancies.

Thirty-four patients with haematological malignancies were studied to investigate the effect of empirical broad-spectrum antibiotic therapy (ceftazidime and gentamicin) on the gastro-intestinal flora. Twenty-five patients with acute myeloid leukaemia or post-autologous bone-marrow transplantation were given framycetin, nystatin and colistin (Fracon), and two patients with non-Hodgkin's Lymphoma were on co-trimoxazole, as long-term gut prophylaxis. Semi-quantitative microbiology was carried out on oropharyngeal swabs and quantitative microbiology on faecal specimens. The oropharyngeal flora consisted mainly of streptococci, coagulase-negative staphylococci and coryneforms, and was little affected by ceftazidime/gentamicin. A strain of Enterobacter cloacae resistant to ceftazidime and gentamicin colonized one patient, who later developed septicaemia. The faecal flora of patients on Fracon was dominated by enterococci; the few enterobacteria present were eliminated by ceftazidime/gentamicin. The anaerobic flora was absent in 15% of patients; in the remainder, it consisted mainly of Bacteroides spp., and was little affected by ceftazidime/gentamicin. The faecal flora of patients not on Fracon always contained anaerobes, and some strains of enterobacteria persisted throughout antibiotic treatment. None of the patients was colonized by Clostridium difficile or Pseudomonas aeruginosa. Broad-spectrum therapy with ceftazidime and gentamicin appeared to have little effect on the gastro-intestinal flora, except to encourage the overgrowth of enterococci and reduce the numbers of enterobacteria.

Microbiological study of bladder tumors, their histology and infective complications.

The microbiology of bladder tumors and the infective complications of transurethral resection (TURBT) were studied prospectively in 51 patients. Patients taking antimicrobials were excluded. Those with significant preoperative bacteriuria were included in the study when results of the preoperative urine specimen were unavailable at the time of operation. Infected tumors were found in 18 percent of males and 75 percent of females. A wide range of bacteria, including anaerobes, was isolated; when streptococci or coliforms were cultured from the tumor, they were always found in significant numbers in the preoperative urine specimen. Perioperative bacteremia and postoperative complications requiring parenteral antibiotics were more common in females and in patients with significant preoperative bacteriuria. No correlation was found between tumor infection and histologic grade or stage of tumor. Patients with sterile preoperative urine and positive bacterial cultures from tumors were no more likely to have postoperative urinary tract infections than those with negative tumor cultures.

Preformed enzyme profiles of reference strains of gram-positive anaerobic cocci.

The preformed (constitutive) enzyme profiles of 30 type strains and reference strains of gram-positive anaerobic cocci were determined with two commercial systems, RapID ANA and a prototype system from API. Both systems identified Peptostreptococcus anaerobius, Ps. asaccharolyticus, Ps. indolicus, Ps. magnus and Ps. micros accurately, except for one strain of Ps. magnus misidentified as Ps. micros by the RapID ANA system. The indole-negative, butyrate-producing cocci (classified at present as Ps. prevotii and Ps. tetradius) produced several different, unique patterns with the prototype API system, but the results with RapID ANA were often misleading. Eight strains of Hare group cocci produced previously described profiles. Four strains of streptococci produced profiles easily distinguished from those of the gram-positive anaerobic cocci. We conclude that most gram-positive anaerobic cocci can be identified rapidly and reliably to the species level by their preformed enzyme profiles, providing that their underlying classification is sound. Problems were encountered with the butyrate-producing cocci, which appear to be a more heterogeneous group of organisms than is currently acknowledged; further taxonomic studies on these organisms are required.

Identification of gram-positive anaerobic cocci by use of systems for detecting pre-formed enzymes.

Two systems for detecting pre-formed enzymes, RapID ANA and a prototype system from API, were compared in a blind study for their ability to identify 69 gram-positive anaerobic cocci isolated from clinical specimens. Both systems were able to identify Peptostreptococcus anaerobius, Ps. asaccharolyticus and Ps. micros accurately without the need for further tests. The prototype API system identified all isolates of Ps. magnus correctly, but the RapId ANA system misidentified several isolates as Ps. micros. Numerous different enzyme patterns were found with the indole-negative, butyrate-producing cocci (Ps. prevotii and Ps. tetradius), suggesting that this group of organisms may be heterogeneous. We conclude that kits for detecting preformed enzymes are of considerable potential for the identification of gram-positive anaerobic cocci in clinical laboratories.

Oral ciprofloxacin as prophylaxis for optical urethrotomy.

It is known that urethral strictures predispose to bacteriuria. We studied a series of patients undergoing optical urethrotomy to see if antibiotic prophylaxis was justified. Twenty-three patients were randomised to receive either no prophylaxis or a short peri-operative course of oral ciprofloxacin. Two patients with sterile pre-operative urine and two patients with pre-operative bacteriuria given no prophylaxis had post-operative bacteriuria, whereas all patients given ciprofloxacin had sterile urine after operation. Antibiotic prophylaxis may be indicated in patients undergoing optical urethrotomy.

Oral ciprofloxacin as prophylaxis in transurethral resection of the prostate.

A new quinolone antibacterial, ciprofloxacin, was evaluated as oral prophylaxis for transurethral resection of the prostate in a randomised controlled trial. A 3-day course of perioperative ciprofloxacin 250 mg twice daily reduced the post-operative infection rate, the post-operative hospital stay and the frequency of infective complications. Ciprofloxacin was well tolerated and no significant haematological or biochemical side effects were detected.