Sepsis And Concomitant Tb

Sepsis can occur as a coinfection with TB. An inadequate clinical response after treatment of sepsis, e.g. pneumonia, may be due to the presence of concomitant HIV-related TB.

3.10

DISTINGUISHING OTHER HIV-RELATED PULMONARY DISEASES FROM PULMONARY TB

This is a common, and often difficult, diagnostic problem. Several diseases in HIV-positive individuals may present in a similar way, with cough, fever, sometimes chest signs, and CXR shadowing. Pneumonia is the most frequent and important differential diagnosis. Pneumonia can also occur as a coinfection with TB. In each case, a careful clinical assessment is needed. Send sputum samples for AFBs if the patient has had cough for 3 weeks or more.

Acute bacterial pneumonia

This is common in HIV-positive patients. The shorter history usually differentiates pneumonia from PTB. The most common pathogen is Streptococcus pneumoniae. Regardless of HIV status, acute bacterial pneumonia usually responds well to standard treatment with penicillin, cotrimoxazole or ampicillin.

If a patient with presumed pneumonia fails to respond to a full course of standard antibiotics, consider other pathogens, e.g. M. tuberculosis.

Kaposi sarcoma (KS)

The clinical recognition of KS is straightforward when there are typical lesions on the skin and mucous membranes.The diagnosis of pulmonary or pleural KS is more difficult.The patient usually presents with cough, fever, haemoptysis and dyspnoea, and usually has KS lesions elsewhere. CXR shows a diffuse nodular infiltrate (with infiltrates spreading out from the hilar regions) or pleural effusion. The pleural fluid is usually blood-stained. Cytology may provide the diagnosis. It can be difficult to rule out concurrent PTB.

Pneumocystis carinii pneumonia (PCP)

Adult PCP is less commonly seen in patients with AIDS in sub-Saharan Africa than in developed countries.The patient usually presents with dry cough and progressive dyspnoea.The table below shows the clinical and CXR features that help to distinguish PCP from PTB.

Clinical and CXR features of PCP and TB

Typical of PCP

Typical of TB

Typical of PCP

Typical of TB

symptoms

dry cough

productive cough

sputum mucoid (if any)

purulent sputum

dyspnoea

pleuritic chest pain

haemoptysis

signs

may be normal

signs of consolidation

fine inspiratory crackles

signs of pleural effusion

CXR

bilateral diffuse

lobar consolidation

interstitial shadowing

cavitation

may be normal

pleural effusion

intrathoracic

lymphadenopathy

The definitive diagnosis of PCP rests on finding the cysts in induced sputum, broncho-alveolar lavage or biopsy specimens. These investigations are often not possible in district hospitals. The diagnosis therefore depends on the clinical and CXR features, exclusion of TB and response to a trial of high-dose cotrimoxazole, combined with corticosteroids if there is severe dyspnoea.

Other conditions

Other uncommon conditions are cryptococcosis and nocardiosis.They may present in a similar way to TB. The diagnosis of pulmonary cryptococcosis rests on finding the fungal spores in sputum smears. Nocardiosis may be particularly difficult to differentiate from TB. The CXR often shows upper lobe, cavitary infiltrates.The organism may also be weakly positive on acid-fast staining.Associated soft-tissue and brain abscesses raise clinical suspicion. The diagnosis rests on finding beaded and branching Gram-positive rods on sputum smear. In South-East Asia, penicilliosis (due to a fungus called Penicillium marneffei) and melioidosis can present in a similar way to PTB and may be HIV-related.The same is true for common fungal infections (paracoccidioidomycosis and histoplasmosis) in the Americas.

I I SUGGESTIONS FOR FURTHER READING I I

Crofton J, Horne N, Miller F. Clinical tuberculosis, second edition. London, MacMillan Press Limited, 1999.

Harries AD, Maher D, Nunn P An approach to the problems of diagnosing and treating adult smear-negative pulmonary tuberculosis in high-HIV-prevalence settings in sub-Saharan Africa. Bulletin of the World Health Organization, 1998, 76: 651-662.

International Union Against Tubertculosis and Lung Disease. Technical guide. Sputum examination for tuberculosis by direct microscopy in low-income countries. Fifth edition. Paris, 2000.

Toman K. Tuberculosis. Case finding and chemotherapy. Geneva, WHO, 1979.

World Health Organization. Tuberculosis handbook. Geneva, 1998, (WHO/TB/98.253).

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