Anaerobic Pleuropulmonary Infections

Anaerobic pleuropulmonary infections Clinical considerations Anaerobic infections are undoubtedly the most commonly overlooked of all bacterial infections. This is the case in pleuropulmonary infections, Sydney M. Finegold, M.D.* particularly when specimens for anaerobic culture John G. Bartlett, M.D.f usually are not obtained and standard micro- biologic techniques often are inadequate. The purpose of this paper is to discuss a few of the clinical problems associated with anaerobic pleuropulmonary infections, to mention techniques for collection of materials for proper culture of anaerobic pulmonary pathogens, and to consider briefly the spectrum of pulmonary dis- eases produced by anaerobes based on our recent experiences. Figure 1 is the posteroanterior chest roentgenogram of a 67-year-old man who had just been ad- mitted to the hospital with an extensive necrotizing pneumonia involving much of the left lung. There was apparently an empyema at the right base as well, but numerous attempts at recovering fluid from this area by thoracentesis were unsuc- cessful. Coughed sputum culture yielded Pseudo- monas aeruginosa in heavy growth. The house of- ficer questioned this laboratory report, since this • Department of Medicine, Wads- worth Veterans Hospital, and the patient had not been hospitalized previously, and University of California Medical it would be most unusual for someone to come Center, Los Angeles, California. into the hospital with an extensive necrotizing f Infectious Disease Section, Veter- pneumonia due to P. aeruginosa in the absence of ans Administration Hospital, Sepul- any severe underlying disease. Furthermore, the veda, California and the University of California Medical Center, Los patient had been chronically ill for 6 months and Angeles, California. had lost 27.3 kg before becoming acutely ill and 101 Downloaded from www.ccjm.org on September 26, 2021. For personal use only. All other uses require permission. 102 Cleveland Clinic Quarterly Vol. 42, No. 1 Fig. I. Chest roentgenogram showing necrotizing pneumonia involving left lung. seeking hospitalization. Again, this is oratory report, he undoubtedly would not the clinical picture of Pseudo- have died, inasmuch as anaerobes typi- monas pneumonia. In addition, this cally are resistant to aminoglycosides. patient was an alcoholic and thus This case is not an unusual one. might well have aspirated and was Among 70 patients with documented bringing up foul-smelling sputum, a anaerobic pulmonary infection, there sure indication that anaerobes must be were 23 instances of potential aerobic involved in the process. Accordingly, pathogens (Staphylococcus aureus, 7; a transtracheal aspiration was done to P. aeruginosa, 7; Diplococcus pneumo- bypass the indigenous flora of the niae, 9; Klebsiella-Enterobacter, 2; mouth and upper respiratory tract. Escherichia coli, 4; Haemophilus influ- This specimen yielded no P. aerugi- enzae, 3) recovered from expectorated nosa, but instead six different anaer- sputum, but not found on trans- obic organisms, all in high counts. tracheal aspiration or in material oth- Had the patient been treated with gen- erwise more directly collected. Figure tamicin on the basis of the original lab- 2 shows that there are significant Downloaded from www.ccjm.org on September 26, 2021. For personal use only. All other uses require permission. Spring 1975 Anaerobic pleuropulmonary infections 103 of author. Hoeprich PD: Etiologic diagnosis of lower respiratory tract infections. Calif Med 112: 1-8, 1970.) numbers of both aerobic and anaerobic bacteria in the mouth and upper respiratory passages, and further empha- sizes the necessity of bypassing such areas of normal flora in order to docu- ment accurately the nature of pulmonary infection. This is particularly true in the case of suspected anaerobic infection. Transtracheal aspiration1 is perhaps best performed through the cricothyroid membrane. Figure 3 shows a transtracheal aspiration being performed on a patient. The polyethylene tube has been inserted through the needle into the trachea. The needle has been withdrawn and the specimen is now being obtained by the use of Fig. 3. Photograph showing transtracheal as- suction and a Luken's trap. piration. A second important consideration for the clinician attempting to docu- such specimens will die after relatively ment the presence of anaerobes in pul- brief exposure to air, it is important monary infection is proper transport that the material be placed under an- of the specimen. Since anaerobes in aerobic conditions as soon as possible. Downloaded from www.ccjm.org on September 26, 2021. For personal use only. All other uses require permission. 104 Cleveland Clinic Quarterly Vol. 42, No. 1 type of infection. With the use of transtracheal aspiration, diagnosis was possible even in the absence of empyema and cases could be diagnosed earlier— before development of abscesses or empyema. Table 2 shows the predisposing conditions in the 100 cases. The two major predisposing factors were aspiration, usually related to altered consciousness, and periodontal disease. A Fig. 4. Photograph of gassed-out tube with detailed breakdown of the culture butyl rubber stopper. Figure 4 illustrates a tube which has been gassed out with oxygen-free gas m -0%—"— and stoppered with a butyl rubber stopper. The specimen is injected 1 through the stopper into the anaerobic WS———s — atmosphere and the tube is then capped. Another suitable and less ex- pensive transport technique is shown in Figure 5. Plastic disposable syringes Fig. 5. Photograph of syringes containing with tight-fitting plungers are suitable exudate, with rubber stoppers on needles to for transport purposes. All air is ex- preserve anaerobic conditions. pelled from the syringe and needle, and the needle is then capped with a Table I. Anaerobic pleuropulmonary rubber stopper as for arterial blood gas disease; types of infection measurements. With this transport setup, it is important that the speci- No. of cases men be received in the laboratory 1958- 1969- within 20 minutes. 1968 1972 We consider here the picture of an- Pulmonary abscess with- 6 20 aerobic pleuropulmonary infection as out empyema illustrated by the first 100 cases that Pulmonary abscess with 4 2 we have studied.2 In Table 1, these empyema Necrotizing pneumonitis 7 10 cases are listed in terms of the type of without empyema pulmonary involvement and in two Necrotizing pneumonitis 6 1 time periods. During the earlier time with empyema period, transtracheal aspiration was Empyema without abscess 20 8 seldom used and empyema fluid was Pneumonitis without em- 0 15 pyema or abscess the most common source of material Infected bronchogenic 1 0 for establishing this diagnosis. Thus, carcinoma cavity the cases documented between 1969 and 1972, when transtracheal aspiration was used commonly, more accu- Total 44 56 rately reflect the true picture of this Total with empyema 30 11 Downloaded from www.ccjm.org on September 26, 2021. For personal use only. All other uses require permission. Spring 1975 Anaerobic pleuropulmonary infections 105 Table 2. Anaerobic pleuropulmonary Bacteroides melaninogenicus) were disease; predisposing conditions particularly common. However, Bac- (100 cases) teroides fragilis was also present in 21% of cases. Figures 6 and 7 show the No. of cases microscopic morphology of F. nuclea- Aspiration tum and B. melaninogenicus, respec- Altered consciousness 63 tively. Anaerobic and microaerophilic Dysphagia 5 streptococci and cocci were also seen Intestinal obstruction 5 with some frequency in these infec- Preceding anaerobic infection tions. Anaerobic gram-positive bacilli Periodontitis 30 Intraabdominal 6 and Clostridia were less commonly en- Local underlying conditions countered. Potential aerobic pathogens Bland pulmonary infarction 9 were recovered from one third of these Bronchogenic carcinoma 7 cases. Despite the presence of these aer- Bronchiectasis 6 obic pathogens, quantitative aspects of Systemic underlying condition 13 None apparent 15 the bacteriology as well as distinctive clinical features indicated that these infections were anaerobic in origin. sources utilized in the diagnosis of Symptoms were commonly present 2 to these cases is noted in Table 3. Distinc- 4 weeks prior to therapy when abscess tive clinical features which suggested formation or empyema was part of the the possibility of anaerobic pulmonary clinical picture (Table 5). Cases with infection in these 100 cases were pul- only pneumonitis had a much shorter monary parenchymal necrosis (70 duration of symptoms prior to therapy cases), subacute or chronic presenta- and were undoubtedly treated before tion (57 cases), suspected aspiration (74 they had an opportunity to develop cases), and putrid discharge (53 cases). these complications. Note in Table 5, Only the putrid discharge is virtually also, that fever persists for some time specific, although one must keep in after therapy has been instituted, par- mind that odor may be imparted to ticularly in the case of empyema. In sputum from anaerobic processes such as gingivitis in the mouth. Parenchy- mal necrosis is not specific for anaero- Table 3. Anaerobic pleuropulmonary bic infection, but is commonly seen in disease; culture sources this condition. Subacute or chronic (100 cases) presentation of the illness, noted in al- No. of cases most two thirds of the cases, is unusual for bacterial pulmonary infections Pleural fluid 40 (7)* other than tuberculosis or mycotic

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