Microbiology of infected pilonidal sinuses.

Aspirates of pus from infected pilonidal sinuses in 75 patients showed bacterial growth. Anaerobic bacteria only were recovered in 58 (77%) specimens, aerobic bacteria only in three (4%), and mixed aerobic and anaerobic bacteria in 14 (19%). Two hundred and nine isolates were recovered: 147 anaerobes (2.0 isolates a specimen) and 62 aerobes (0.8 a specimen). The predominant anaerobes were Bacteroides sp (81 isolates, including 29 Bacteroides fragilis group) and 51 anaerobic cocci. The predominant aerobes were Escherichia coli (n = 15), Proteus sp (n = 9), group D streptococcus (n = 7), and Pseudomonas sp (n = 7). This study highlights the polymicrobial nature and predominance of anaerobic bacteria in infected pilonidal sinuses.     

Microbiology of postthoractomy sternal wound infection.

Specimens from 74 patients with postthoractomy sternal wound infection were studied for aerobic and anaerobic bacteria. Bacterial growth was obtained in specimens from 65 patients (88%). Aerobic or facultative bacteria only were recovered in 50 specimens (77%), anaerobic bacteria only in 6 (9%), and mixed aerobic, facultative, and anaerobic bacteria in 9 (14%). Eighty-seven isolates were recovered (1.3 per specimen): 68 aerobic or facultative (1.0 per specimen) and 19 anaerobic (0.3 per specimen). The predominant aerobes were Staphylococcus epidermidis (28 isolates), Staphylococcus aureus (21 isolates), and members of the family Enterobacteriaceae (14 isolates). The predominant anaerobes were Peptostreptococcus spp. (10 isolates), Bacteroides spp. (4 isolates), and Clostridium spp. (3 isolates). Polymicrobial infection occurred in 18 instances (28%). A single organisms was recovered in 47 instances (72%); these included 20 isolates of S. epidermidis, 15 of S. aureus, 5 of Enterobacteriaceae, and 4 of anaerobes. These data highlight the previously unrecognized polymicrobial aerobic and anaerobic bacteriology in a percentage of patients with postthoractomy sternal wound infection.     

Aerobic and anaerobic microbiology in intra-abdominal infections associated with diverticulitis

The aerobic and anaerobic microbiology of intra-abdominal infections associated with diverticulitis was studied in 110 specimens from the peritoneal cavity after intestinal perforation and in 22 specimens from abdominal abscesses. Anaerobic bacteria only were isolated from 17 (15%) of the peritoneal specimens, aerobic bacteria only from 12 (11%) and mixed aerobic and anaerobic flora from 81 (74%). A total of 339 bacterial isolates was detected in peritoneal cultures (3.1 per specimen), comprising 155 aerobes (1.4 per specimen) and 184 anaerobes (1.7 per specimen). Anaerobic bacteria only were isolated in 4 (18%) abscesses, aerobes alone in one (5%) and mixed aerobic and anaerobic flora in 17 (77%). A total of 72 bacterial isolates (3.3 per specimen) was detected in abdominal abscesses - 35 aerobes (1.6 per specimen) and 37 aerobes (1.7 per specimen). The predominant aerobic and facultative bacteria in abdominal infections were Escherichia coli and Streptococcus spp. The most frequently isolated anaerobes were Bacteroides spp. (B. fragilis group), Peptostreptococcus, Clostridium and Fusobacterium spp.     

Presence of beta-lactamase-producing bacteria and beta-lactamase activity in abscesses

The presence of beta-lactamase-producing bacteria (BLPB) in abscesses was investigated in 109 abscesses. Single isolates were recovered in 23 (21%) instances and were predominantly Staphylococcus aureus. The other abscesses yielded growth of two or more aerobic and/or anaerobic organisms. Aerobic bacteria were recovered in 28 (26%) of the aspirates, anaerobic bacteria in 41 (38%), and mixed aerobic and anaerobic bacteria in 40 (36%). A total of 362 isolates (247 anaerobes and 115 aerobes) were recovered, accounting for 3.3 isolates per specimen (2.2 anaerobes and 1.1 aerobes). One hundred beta-lactamase-producing organisms were recovered in 88 (77%) specimens. These included all 28 isolates of Bacteroides fragilis, 18 of 30 Bacteroides melaninogenicus, 42 of 43 S. aureus, and 11 of 14 Escherichia coli. Beta-lactamase activity was detected in 40 (55%) of the purulent specimens when using the chromogenic cephalosporin nitrocefin method. These data demonstrate the presence of aerobic and anaerobic BLPB in abscesses.     

Anaerobes in pleuropulmonary infections

A total of 76 anaerobes and 122 aerobes were isolated from 100 patients with pleuropulmonary infections, e.g. empyema (64), pleural effusion (19) and lung abscess (13). In 14% of the patients, only anaerobes were recovered, while a mixture of aerobes and anaerobes was encountered in 58%. From all cases of lung abscess, anaerobic bacteria were isolated, alone (04) or along with aerobic bacteria (13). From empyema and pleural effusion cases, 65.6% and 68.4% anaerobes were recovered respectively. Amongst anaerobes, gram negative anaerobic bacilli predominated (Prevotella melaninogenicus 16, Fusobacterium spp. 10, Bacteroides spp. 9), followed by gram positive anaerobic cocci (Peptostreptococcus spp. 31). Coliform bacteria (45) and Pseudomonas aeruginosa (42) were the predominant aerobic isolates.     

Clinical and microbiological features of necrotizing fasciitis.

The microbiological and clinical characteristics of 83 patients with necrotizing fasciitis (NF) treated over a period of 17 years are presented. Bacterial growth was noted in 81 of 83 (98%) of specimens from patients with NF. Aerobic or facultative bacteria only were recovered in 8 (10%) specimens, anaerobic bacteria only were recovered in 18 (22%) specimens, and mixed-aerobic-anaerobic floras were recovered in 55 (68%) specimens. In total, there were 375 isolates, 105 aerobic or facultative bacteria and 270 anaerobic bacteria, for an average of 4.6 isolates per specimen. The recovery of certain bacteria from different anatomical locations correlated with their distribution in the normal flora adjacent to the infected site. Anaerobic bacteria outnumbered aerobic bacteria at all body sites, but the highest recovery rate of anaerobes was in the buttocks, trunk, neck, external genitalia, and inguinal areas. The predominant aerobes were Staphylococcus aureus (n = 14 isolates), Escherichia coli (n = 12), and group A streptococci (n = 8). The predominant anaerobes were Peptostreptococcus spp. (n = 101), Prevotella and Porphyromonas spp. (n = 40), Bacteroides fragilis group (n = 36), and Clostridium spp. (n = 23). Certain clinical findings correlated with some bacteria: edema with B. fragilis group, Clostridium spp., S. aureus, Prevotella spp. and group A streptococci; gas and crepitation in tissues with members of the family Enterobacteriaceae and Clostridium spp.; and foul odor with Bacteroides spp. Certain predisposing conditions correlated with some organisms: trauma with Clostridium spp.; diabetes with Bacteroides spp., members of the family Enterobacteriaceae, and S. aureus; and immunosuppression and malignancy with Pseudomonas spp. and members of the family Enterobacteriaceae.(ABSTRACT TRUNCATED AT 250 WORDS)     

The aerobic and anaerobic bacteriology of perirectal abscesses.

The microbiology of perirectal abscesses in 144 patients was studied. Aerobic or facultative bacteria only were isolated in 13 (9%) instances, anaerobic bacteria only were isolated in 27 (19%) instances, and mixed aerobic and anaerobic flora were isolated in 104 (72%) instances. A total of 325 anaerobic and 131 aerobic or facultative isolates were recovered (2.2 anaerobic isolates and 0.9 aerobic isolates per specimen). The predominant anaerobes were as follows: Bacteroides fragilis group (85 isolates), Peptostreptococcus spp. (72 isolates), Prevotella spp. (71 isolates), Fusobacterium spp. (21 isolates), Porphyromonas spp. (20 isolates), and Clostridium spp. (15 isolates). The predominant aerobic and facultative bacteria were as follows: Staphylococcus aureus (34 isolates), Streptococcus spp. (28 isolates), and Escherichia coli (19 isolates). These data illustrate the polymicrobial aerobic and anaerobic microbiology of perirectal abscesses.     

Use of the BacT/Alert Blood Culture System for Culture of Sterile Body Fluids Other than Blood

Studies have demonstrated that large-volume culture methods for sterile body fluids other than blood increase recovery compared to traditional plated-medium methods. BacT/Alert is a fully automated blood culture system for detecting bacteremia and fungemia. In this study, we compared culture in BacT/Alert standard aerobic and anaerobic bottles, BacT/Alert FAN aerobic and FAN anaerobic bottles, and culture on routine media for six specimen types, i.e., continuous ambulatory peritoneal dialysate (CAPD), peritoneal, amniotic, pericardial, synovial, and pleural fluids. Specimen volumes were divided equally among the three arms of the study. A total of 1,157 specimens were tested, with 227 significant isolates recovered from 193 specimens. Recovery by method was as follows: standard bottles, 186 of 227 (82%); FAN bottles, 217 of 227 (96%); and routine culture, 184 of 227 (81%). The FAN bottles recovered significantly more gram-positive cocci (P < 0.001), Staphylococcus aureus (P = 0.003), coagulase-negative staphylococci (P = 0.008), gram-negative bacilli (P < 0.001), Enterobacteriaceae (P = 0.005), and total organisms (P < 0.001) than the routine culture. There were no significant differences in recovery between the standard bottles and the routine culture. The FAN aerobic bottle recovered significantly more gram-positive cocci (P < 0.001), S. aureus isolates (P < 0.001), coagulase-negative staphyococci (P = 0.003), and total organisms (P < 0.001) than the standard aerobic bottle, while the FAN anaerobic bottle recovered significantly more gram-positive cocci (P < 0.001), S. aureus isolates (P < 0.001), Enterobacteriaceae (P = 0.03), and total organisms (P < 0.001) than the standard anaerobic bottle. For specific specimen types, significantly more isolates were recovered from the FAN bottles compared to the routine culture for synovial (P < 0.001) and CAPD (P = 0.004) fluids. Overall, the FAN bottles were superior in performance to both the standard bottles and the routine culture for detection of microorganisms from the types of sterile body fluids included in this study.     

Microbiology of retroperitoneal abscesses in children.

Samples of pus from 41 children with retroperitoneal abscess treated between 1974 and 1994 yielded a total of 125 organisms (3.0 isolates/specimen); 58 isolates were aerobic and facultative species (1.4/specimen) and 67 were anaerobic (1.6/specimen). Aerobic bacteria only were isolated from 7 (17%) abscesses, anaerobic bacteria only from 3 (7%) and mixed aerobic and anaerobic bacteria from 31 (76%); 34 (83%) infections were polymicrobial. The predominant aerobic and facultative isolates were Escherichia coli (19 isolates) and Staphylococcus aureus (6), and the predominant anaerobes were Peptostreptococcus spp. (18 isolates), Bacteroides spp. (22) and Prevotella spp. (5).     

Bacteriology of acute and chronic ethmoid sinusitis

Aspirates from 26 acutely and 17 chronically infected ethmoid sinuses were studied. Thirty-seven aerobes and 10 anaerobes were recovered from isolates from patients with acute sinusitis. Streptococcus pneumoniae and Haemophilus influenzae were predominant. Twenty-seven aerobes and 41 anaerobes were found in isolates from patients with chronic sinusitis. The predominant isolates were anaerobic gram-negative bacilli and Peptostreptococcus spp.     

Microbiology of secondary bacterial infection in scabies lesions.

Aerobic and anaerobic bacteria were grown from specimens obtained from 30 children with secondarily infected scabies lesions. Aerobic or facultative bacteria only were present in 14 (47%) patients, anaerobic bacteria only were present in 6 (20%) patients, and a mixed anaerobic-aerobic flora was present in 10 (33%) patients. Fifty isolates were recovered (1.7 per specimen); 27 were aerobic or facultative bacteria and 23 were strict anaerobes. The predominant aerobic and facultative bacteria were Staphylococcus aureus (nine isolates), group A streptococci (five isolates), and Pseudomonas aeruginosa (three isolates). The predominant anaerobes were Peptostreptococcus sp. (nine isolates) and pigmented Prevotella and Porphyromonas spp. (four isolates). Single bacterial isolates were recovered from nine (30%) patients; five of these were S. aureus. Sixteen organisms isolated from 12 (40%) patients produced the enzyme beta-lactamase. Organisms that resided in the mucous membranes close to or in contact with the lesions predominated in those infections. Enteric gram-negative rods were recovered in leg and trunk lesions. Group A streptococci and S. aureus predominated in finger and hand lesions. Bacteroides fragilis group and Clostridium sp. were isolated from leg lesions, and pigmented Prevotella sp. and Porphyromonas and Fusobacterium spp. were recovered from finger lesions. The polymicrobial etiology of secondarily infected scabies lesions in children and the association of bacterial flora with the anatomical sites of the lesions are demonstrated.     

Aerobic and anaerobic microbiology of suppurative sialadenitis

Aspirates of pus from acute suppurative sialadenitis were investigated for the presence of aerobic and anaerobic bacteria. A total of 47 specimens, 32 from parotid, 9 from submandibular and 6 from sublingual glands yielded bacterial growth. Fifty five isolates, 25 aerobic and 30 anaerobic, were isolated from parotid infection: anaerobic bacteria only were detected in 13 (41%) specimens, aerobic or facultative bacteria only in 11 (34%) and mixed aerobic and anaerobic bacteria in 8 (25%). Of a total of 17 isolates, 8 aerobic and 9 anaerobic, from submandibular gland infection: anaerobic bacteria only were detected in 3 (33%) specimens, aerobic or facultative bacteria only in 4 (44%) and mixed aerobic and anaerobic bacteria in 2 (22%). Ten isolates, 5 aerobic and 5 anaerobic, were from sublingual gland infection: anaerobic bacteria only were detected in 2 (33%) specimens, aerobic or facultative bacteria only in 2 (33%) and mixed aerobic and anaerobic bacteria in 2 (33%). The predominant aerobes were Staphylococcus aureus and Haemophilus influenzae while the predominant anaerobes were gram-negative bacilli (including pigmented Prevotella and Porphyromonas spp., and Fusobacterium spp.) and Peptostreptococcus spp. The study highlights the polymicrobial nature and importance of anaerobic bacteria in acute suppurative sialadenitis.     

Aerobic and anaerobic microbiology of biliary tract disease.

A retrospective analysis of the experiences of two military hospitals over 4 years in the recovery of organisms from biliary tract specimens was done. Bacterial growth was obtained in 123 bile specimens. Aerobic and facultative bacteria only were present in 59 specimens (48%), aerobic bacteria only were present in 4 specimens (3%), and mixed anaerobic and aerobic or facultative bacteria were present in 60 specimens (49%). Of 286 isolates recovered, 216 were aerobic or facultative (1.8 per specimen) and 70 were anaerobic (0.6 per specimen). The predominant bacteria were Escherichia coli (71 isolates), group D streptococci (42 isolates), Klebsiella sp. (29 isolates), Clostridium sp. (27 isolates), Bacteroides sp. (28 isolates), and Enterobacter sp. (16 isolates). Polymicrobial infections were present in 108 instances (88%). A higher recovery rate of anaerobes was present in patients with chronic infections than in those with acute infections and did not correlate with the presence of gallstones or use of antimicrobial prophylaxis.     

Comparison of two transport systems for recovery of aerobic and anaerobic bacteria from abscesses.

An evaluation of two commercially available swab transport systems, Port-A-Cul (PAC; BBL Microbiology Systems, Cockeysville, Md.) and Anaerobic Specimen Collector (ASC; Becton Dickinson Vacutainer Systems, Rutherford, N.J.), in the recovery of organisms from clinical specimens was done. Fifteen abscesses were drained, and swabs of their contents were placed in the transport systems until they were inoculated for detection of aerobic and anaerobic bacteria. The swabs were plated immediately after collection and after delays of 4, 24, 48, and 72 h. A total of 70 bacterial isolates, 47 anaerobes and 23 aerobes, were recovered from specimens inoculated immediately after collection. The survival of anaerobic bacteria was better in the PAC system than in the ASC system. This was evident as the length of delay in cultivation was extended. At 4 h, 46 anaerobic isolates were recovered in the PAC system, compared with 39 in the ASC system (P less than 0.1). At 24 h, 45 isolates were recovered in the PAC system and 26 isolates were recovered in ASC (P less than 0.001); at 48 h, 40 were recovered in PAC and 15 were recovered in ASC; and at 72 h, 32 were recovered in PAC and 6 were recovered in ASC. There were no differences between the systems in the recovery of aerobic bacteria. These data demonstrate the usefulness of the PAC system in the recovery of anaerobes and the need for quality control of all transport systems for anaerobic bacteria.     

Comparison of recovery of blood culture isolates from two BacT/ALERT FAN aerobic blood culture bottles with recovery from one FAN aerobic bottle and one FAN anaerobic bottle

Traditionally, a routine blood culture for adult patients consisted of paired aerobic and anaerobic bottles, but the routine use of an anaerobic blood culture bottle has been challenged in recent years. In this study, we compared the recovery of two FAN aerobic bottles with one FAN aerobic and one FAN anaerobic bottle. Each pair of bottles was collected by a separate collection procedure, and each bottle held a recommended 8- to 12-ml draw. A total of 704 clinically significant isolates were recovered from 8,620 sets (17,240 pairs), with 487 (69.2%) isolates recovered from one or both bottles in each pair of bottles, 86 isolates (12.2%) recovered only from the FAN aerobic-FAN aerobic pair, and 131 isolates (18.6%) recovered only from the FAN aerobic-FAN anaerobic pair. Significantly more total organisms (P = 0.002), gram-positive cocci (P = 0.03), Staphylococcus aureus (P = 0.05), Enterobacteriaceae other than Escherichia coli (P = 0.02), and anaerobes (P = 0.01) were recovered from the FAN aerobic-FAN anaerobic pair than from the FAN aerobic-FAN aerobic pair. A separate analysis was performed on the 618 isolates that were recovered from the FAN aerobic-FAN anaerobic pair to compare recovery by bottle type. Significantly more S. aureus (P = 0.005) and anaerobes (P < 0.001) were recovered from the FAN anaerobic bottle, while significantly more coagulase-negative staphylococci (P = 0.01), Streptococcus pneumoniae (P = 0.03), and other gram-negative bacilli (P = 0.004) were recovered from the FAN aerobic bottle. These results support the routine use of a FAN anaerobic bottle for use in the culture of blood with the BacT/ALERT system in our institution. These results also suggest that the decision of whether to routinely utilize an anaerobic blood culture bottle should be influenced by the overall recovery of bacteria and yeast, the recovery of specific types of bacteria or yeast, the medium type, and the blood culture system utilized by the laboratory.     

Aerobic and anaerobic bacteriology of purulent nasopharyngitis in children.

Cultures of aerobic and anaerobic bacteria were obtained from the inferior nasal meatus of 25 children with purulent nasopharyngitis and from 25 controls. Microorganisms were isolated from all specimens. A total of 98 isolates (3.9 per patient), 45 aerobes (1.8 per patient) and 53 anaerobes (2.1 per patient), were isolated in patients with purulent nasopharyngitis. Seventy-three isolates (2.9 per patient), 47 aerobes (1.9 per patient) and 26 anaerobes (1.0 per patient) were found in the controls. The organisms recovered in statistically significantly higher numbers in patients with nasopharyngitis were Streptococcus pneumoniae, Haemophilus sp., Peptostreptococcus spp., Fusobacterium spp., and Bacteroides spp. The organisms recovered in significantly higher numbers in controls were Staphylococcus aureus and Propionibacterium acnes. beta-Lactamase activity was detected in 19 isolates recovered from 15 individuals (9 patients and 6 controls). These findings demonstrate the aerobic-anaerobic polymicrobial flora associated with purulent nasopharyngitis. Further studies are indicated to evaluate the pathogenic role of these organisms in this condition.     

Cervical bacterial flora in infertile and pregnant women

The cervical bacterial flora in early pregnancy, labour, and infertility was assessed qualitatively. The cervix harboured several types of bacteria in both pregnant and infertile women. In the latter group, however, fewer species were found. The incidence of a mixed aerobic and anaerobic flora differed significantly between patient categories as did the frequency with which only aerobic isolates were obtained. There was also a significant difference between patient groups with regard to the incidence of anaerobic isolates. Among the anaerobic bacteria, peptostreptococci and bacteroides species were the dominating ones whereas coagulase-negative staphylococci were the most prevalent aerobic bacteria. Lactobacilli constituted 29–44% of the anaerobic bacteria found in the pregnant cervix and 52% of those found in the infertile cervix. The distribution of different aerobes as well as anaerobes was similar in pregnant and infertile patients.     

Bacteriological spectrum of cholecystitis and its antibiogram

Bile Cultures for aerobic and anaerobic bacteria were carried out on 125 samples from patients with chronic cholecystitis with cholelithiasis. Cultures grew 71(56.8%) aerobes and 17(13.6%) anaerobic microorganisms. Polymicrobial infection was seen in 7(16.2%) cases. E. coli (45.07%) and Klebsiella (25.35%) were predominant among the aerobes and Bacteroides fragilis (58.82%) was predominant among the anaerobes. Highest incidence of the disease was observed in the fourth decade of life and females predominated in this study.     

Bacteremia due to obligate anaerobes following large bowel surgery in a tertiary care hospital in South India

In view of the rising incidence of Anaerobic bacteremia(AB), the use of anaerobic blood culture bottles have been recommended in addition to the aerobic blood culture bottles. The need to perform antimicrobial susceptibility testing(AST) for anaerobes has become mandatory owing to increasing metronidazole resistance. The frequency of AB following large bowel surgery and the metronidazole susceptibility for members of the Bacteroides fragilis group were determined. The incidence of AB was found to be 16%. Seventeen obligate anaerobes were isolated in total, of which B. fragilis was the most common. Two of twelve isolates of B. fragilis were resistant to metronidazole.     

Bacteriology of diabetic foot ulcers.

Seventy five diabetic foot ulcers were cultured using optimal aerobic and anaerobic microbiologic techniques. There were a total of 223 isolates (162 aerobes and 61 anaerobes) representing an average of 2.97 bacterial species per specimen. Mixed organisms were the most common isolates. Staphylococcus aureus was the commonest isolate being recovered in 60% of cases. Anaerobic organisms were isolated in 46 patients (61.33%) and the most frequent anaerobe isolated was Bacteroides fragilis. The other organisms predominantly isolated were Proteus, Klebsiella, Pseudomonas, Peptoccus and Clostridia. Antibiogram showed discouraging pattern with commonly used antibiotics. Metronidazole and gentamicin were the most effective antimicrobial agents against anaerobic and aerobic organisms respectively. Appreciation of the causative organisms in diabetic foot and their antibiotic sensitivity is essential for institution of appropriate antibiotic therapy.