Journal: Approach to Common Bacterial Infections: Community acquired pneumonia

Community acquired pneumonia (CAP) -different in children & adults.

2 main challenges in diagnosis of CAP:

defn of CAP-young children-viral & bacterial infections .

Identification of pathogen-unnecessary antibiotic use.

Challenge for general pediatrician –recognize lower respiratory tract illness-treat with antibiotics if bacterial pneumonia suspected.

WHO cough or difficult breathingFast breathing 2month-1yr : >50 br/min

1 yr-5yr : >40 br/min

BTS Persistent or repetitive fever >38.5C with chest recession & increased respiratory rate.

IDSA Signs & symptoms of pneumonia in previously healthy child caused by infection that has been acquired outside hospital.

First clinical issue- diagnose CAP & determine which pathogen responsible.

Streptococcus pneumoniae & Haemophilusinfluenza type b (Hib) –fatal pneumonia in children.

Hib & pneumococcal vaccine-decline in Hib

Atypical organisms –mycoplasmapneumoniae, chlamydia pneumoniae-one third of cases.

Viral pathogens accounts for clinical pneumonia- children < 1yr: 77 %

>2 yr:59 %

Influenza A virus, RSV, para influenza virus 1,2,3.

Study by Singleton & colleagues recovered respiratory virus from 90 % of Alaskan children younger than 3yrs-hospitalized with respiratory infections.

Case control study of 865 children –RSV,PIV, hMPV & Influenza virus –common in hospitalized cases than control children.

Rhino virus –associated with bronchiolitis, asthma & wheezing.

HMPV –isolated from nasopharyngeal & throat specimens of hospitalized children with CAP.

Human Boca virus

WU & KI polyoma viruses

SARS –associated corona virus

Dominguez & colleagues detected corona virus RNAs -5% pediatric respiratory specimens.

Presented with vomiting or diarrhoea & 8% with meningoencephalitis or seizures.

Fungal pathogens-Histoplasma, Blastomyces, Cryptococcus-pneumonia in immunocompromised.

AGE TESTS

BIRTH-20 DAYS

Group B Streptococci Blood culture-progressive symptoms & clinically deteriorate.

Gram negative Enteric Bacteria

Listeria Monocytogenes

21-90 DAYS

Chlamydia trachomatis NP culture or NP PCR

RSV, PIV3 NP swab for PCR, DFA staining, immunofluorescence

Streptococcus pneumoniae Blood culture

Bordetella pertussis Blood culture, immunofluorescence

Staphylococcus aureus Blood & pleural fluid culture

AGE TESTS

4 MONTHS-4 YR

RSV, Para influenza virus, Influenza virus, Adeno virus, Rhino virus

NP swab for PCR or immunofluorescence, viral culture, DFA staining

Streptococcus pneumoniae Blood culture, Urinary antigen, Pneumolysin based PCR of blood

Haemophilus Influenza Blood & Pleural fluid culture

Mycoplasma Pneumoniae Quadrupling of acute & convalescent serology, IgMantibody in serum, throat or NP swab PCR

Mycobacterium tuberculosis Sputum culture , Gastric aspirate, Positive Tuberculin skin test

AGE TESTS

5 YR-15 YRS

Mycoplasma pneumoniae Quadrupling of acute & convalescent serology, IgM antibody in serum, Throat or NP swab PCR.

Chlamydia pneumoniae Quadrupling, NP culture or NP PCR

Streptococcus pneumoniae Blood culture, Urinary antigen, Pneumolysin based PCR

•Influenza A or B, Adeno virus NP swab for PCR orimmunofluorescence, viral culture, DFA staining

Haemophilus influenza Blood & Pleural fluid culture

Mycobacterium tuberculosis Sputum or gastric aspirate, positive tuberculin skin test, Interferon gamma release assay.

Streptococcus pneumoniae

Staphylococcus aureus

Group A Streptococcus

Haemophilus influenza type b

Mycoplasma pneumoniae

Adeno virus

Viruses-Varicella zoster virus, Corona virus, Entero viruses (Coxsackie virus, Echo virus), Cytomegalo virus, Epstein Barr virus, Mumps virus, Herpes simplex virus, Boca virus, Polyoma virus, Measles virus, Hanta virus.

Chlamydia psittaci Coxiella burnetii

Bacteria-streptococcus pyogenes, klebsiellapneumoniae, E.coli, Legionella, Neisseriameningitidis, Brucella, Leptospira.

Fungi-Coccidioides immitis, Histoplasmacapsulatum, Blastomyces dermatitidis.

PATIENT HISTORY

Symptoms of pneumonia-fever, chills, cough

-can overlap with bacterial sepsis or severe anaemia.

Signs-crackles, egophony-more specific

Chest radiography-gold standard for confirmation of pneumonia.

FACTORS AGENTS

HOST FACTOR

SICKLE CELL DISEASE STREPTOCOCCUS PNEUMONIAE

HIV & CD4 + LYMPHOCYTE COUNT<200

STREPTOCOCCUS PNEUMONIAE, HAEMOPHILUS INFLUENZA, CRYPTOCOCCUS NEOFORMANS, MYCOBACTERIUM TUBERCULOSIS

STRUCTURAL LUNG DISEASE( BRONCHIECTASIS)

PSEUDOMONAS AEROGINOSA

FACTORS AGENTS

TRAVEL

SOUTH EAST ASIA BULKHOLDERIA PSEUDOMALLEI, MYCOBACTERIUM TUBERCULOSIS

CHINA, TAIWAN, TORONTO, CANADA, MIDDLE EAST

CORONA VIRUS-SARS

TUBERCULOSIS ENDEMIC AREAS MYCOBACTERIUM TUBERCULOSIS

DESERT REGIONS OF SOUTH WESTERN UNITED STATES, CENTRAL & SOUTH AMERICA

COCCIDIODES IMMITIS

OHIO, ST LAWRENCE RIVER VALLEYS

HISTOPLASMA CAPSULATUM

PERU SPOROTHRIX SCHENCKII

FACTOR AGENTS

ENVIORNMENTAL FACTORS

PNEUMONIA OUTBREAK IN A HOMLESS SHELTER

STREPTOCOCCUS PNEUMONIA, MYCOBACTERIUM TUBERCULOSIS

LAWN MOWING –SOUTH CENTRAL & WESTERN STATES, MATHAS VINEYARD

FRANCISELLA TULARENSIS

EXPOSURE TO CATS, SHEEPS, GOATS, CATTLE-WESTERN STATES

COXIELLA BURNETII

SLEEEPING IN A ROSE GARDEN-BALES OF HAY

SPOROTHRIX SCHENCKII

EXPOSURE TO WIND STORM COCCIDIODES IMMITIS, COXIELLA BURNETII

EXPOSURE TO BATS, EXCAVATION HISTOPLASMA CAPSULATUM

ENVIORNMENTAL FACTORS

CAMPING, CUTTING DOWN TREES-MISSISSIPPI RIVER, OHIO RIVER VALLEY

BLASTOMYCES DERMATITIDIS

EXPOSURE TO MOUSE DROPPINGS-FOUR CORNERS & YOSEMITE NATIONAL PARK

HANTA VIRUS

IMMUNOSUPRESSED & EXPOSURE TO HOT TUB- GROSERY STORE MIST MACHINE , RECENT STAY IN HOTEL OR VISIT TO HOSPITAL WITH LEGIONELLACEAE CONTAMINATED DRINKING WATER

LEGIONELLA PNEUMOPHILIA

Cevey –Macherel & colleagues –more than fifth of patients diagnosed with CAP had completely normal breath sounds on admission & ausultation was ruled to be poorly sensitive & specific in diagnosing WHO guideline defined pneumonia.

In another study which defined pneumonia as presence of crepitations, wheeze, bronchial breathing, CXR abnormalities –repiratory rate <40 breaths/min seen in 55% children older than 35 months with diagnosis of pneumonia.

Canadian guidelines –oxygenation as good indicator of severity of disease.

Oxygen saturation recomm. by IDSA as guide for referral of care.

Pneumococcal pneumonia-history of fever, breathlessness, signs of tachypnea, indrawing, toxic appearance.

Mycoplasma pneumonia-cough, chest pain, wheezing, arthralgia, headache. Symptoms more worse than signs.

Mycoplasma pneumonia-common in children aged 5yrs or younger –slow progression, sore throat, low grade fever & cough .

Many children with CAP have mixed bacterial & viral infections.

INDICATIONS OF SEVERE PEDIATRIC CAP

1.Temperature >38.5 C

2. Respiratory rate: infants >70 breaths/min.

older children >50 breaths/min.

3.Moderate to severe recession.

4.Nasal flaring

5.Cyanosis

6.Grunting respiration.

7.Infants-intermittent apnea & not feeding

8. Tachycardia

9.Signs of dehydration.

10.Capillary refill time 2 seconds or more.

CRITERIA FOR HOSPITAL ADMISSION OF A CHILD WITH CAP1.Hypoxemia with O2 less than 90%

2.Infants younger than 3-6 months.3.Suspected or documented CAP caused by pathogen with increased virulence-MRSA

4.Unable to be followed up

TRANSFER TO INTENSIVE CARE

1.Oxygen saturation >92%

2.Severe respiratory distress

3.Sustained tachycardia, inadequate blood pressure

4.Exhaustion

5.Apnea

6.Slow breathing

7.Altered mental status

Neither IDSA nor BTS recommends CXR for confirmation of suspected CAP.

Prospective study in Switzerland enrolling 99 patients found only 79 % had radiographic consolidation with poor correlation b/w radiographic findings & dimnished breath sounds.

Study in U.K by Clark & colleagues showed that lobar CXR changes were not associated with severity.

Study from Brazil –upper lobe involvement was shown to have 84% specificity in predicting severity in children aged 1yr or younger.

IDSA guidelines support postero anterior( PA )

& lateral CXR –patients with hypoxemia or respiratory distress & who have failed an initial course of antibiotic.

BTS guidelines donot recommend a lateral CXR should be performed routinely.

Frontal CXR-100 % sensitive & specific for lobar consolidation but would under diagnose non lobar infiltrates.

Follow up CXRs indicated if child do not improve clinically & with progressive symptoms & clinical deterioration after 48-72hrs of antibiotic therapy.

Most bacterial pneumonia present with lobar infiltrate.

Interstitial infiltrates found in bacterial, viral & atypical pneumonia.

Mycoplasma pneumoniae –have diffuse infiltrate radiologically out of propotion with clinical findings.

Lobar consolidation, atelectasis, nodular infiltration & hilar adenopathy.

Mycoplasma pneumoniae-IgM ELISA testing in serum or plasma

PCR testing –nasal,throat or sputum specimens.

PCR testing detects more mycoplasmainfections than IgM ELISA.

Streptococcus pneumoniae : round infiltrates

Common causes for Round pneumonia :

Streptococcus pneumoniaeKlebsiella pneumoniaeHaemophilus influenzaCoxiella burnetiiMycobacterium tuberculosisFungal infections, Hydatid cyst, Lung abscess

Microbiological recovery sample from infected region of lung-gold standard

Tests: Blood culture, urinary antigen, Pneumolysin based PCR of blood, pleural fluid & secretions.

Any child with suspected CAP –no indications for any general investigations.

Hospitalized child with CAP-testing for potential pathogens & acute phase reactants-WBC, CRP, ESR, Procalcitonin helpful.

Study by Don & colleagues -101 children , showed increase of 4 serum nonspecific inflammatory markers (WBC,CRP,ESR,PCT) was associated with radiological evidence of CAP.

Study by Lahti & colleagues –children 6 months & older showed inhalation of 5% hypertonic saline for 5-10 min –provided good quality sputum sample -90% microbiological yield.

New molecular diagnostic tests available-Rapid antigen detection for respiratory virus.

Age-best predictor of pediatric pneumonia Guidelines for treatment categorized by age &

suspected pathogens.

BTS guidelines recommend children with clinical diagnosis of pneumonia-antibiotics-bacterial & viral pneumonia cannot be differentiated.

IDSA –no antibiotics-viral pathogens-most CAP in preschool aged children.

Streptococcus pneumoniae-most prominent bacterial pathogen –all age groups.

Amoxicillin-first line therapy for all healthy immunized pts.

IDSA guidelines-Amoxicillin 90 mg/kg/day in 2 divided doses.

Atypical bacterial pathogens-Mycoplasmapneumonia-school aged children & older pts.

Macrolide therapy recomm.

Atypical pneumonia : Azithromycin 10 mg/kg on day 1 followed by 5mg/kg daily on days 2-5.

Children aged 5yr or older with presumed bacterial CAP –donot have clinical, laboratory, radiographic evidence to distinguish bacterialfrom atypical CAP-IDSA recommends macrolide can be added to beta lactumantibiotic.

Treatment courses-10 days of beta lactamantibiotics & 5 days for Azithromycin-studied.

Prolonged courses for MRSA.

Canadian guidelines recomm. switching from parenteral to oral therapy after 2-4 days, if child is afebrile without complications.

IDSA & BTS- no recomm. & no randomized controlled studies.

Apart from influenza , no data for antiviral therapy against viruses assoc. pediatric CAP.

Adamantanes & neuraminidase inhibitors –effective against influenza A.

Neuraminidase inhibitors for influenza B.

Genetic variation in influenza strains from year to year –resistant to either class of anti viral agents.

Anti microbial resistant Streptococcus pneumoniae.

Penicillin resistant Pneumococcal isolates.Pneumococcal conjugate vaccine PCV 7 –5 serotypes -89 % penicillin resistant pneumococcal isolates.

IDSA recomm. limiting antibiotic exposure & using antibiotic with narrow spectrum & shortest duration.

Fluoroquinolones (FQ) avoided –children younger than 18 yrs- arthropathy.

Alternative therapy –serious infectious diseases.

Bradley & colleagues -738 children from 6 months to 16 yrs with CAP –levofloxacin & comparator drug. Similar cure rate

Musculoskeletal S.E-arthralgia, myalgia. Emerging drug resistance-FQ effective

alternate therapy.

Children with CAP on adequate therapy should clinically improve within 48-72 hrs.

No improvement-complications pleural effusions, empyema, necrotising pneumonia, septicemia & (staphylococcal aureus -osteomyelitis or septic arthritis ), hemolytic uremic syndrome.

Children with severe pneumonia, empyema & lung abscess –followed up untill complete resolution clinically & on CXR.

Vaccines-crucial role in prevention of pneumonia.

Pertussis cause pneumonia in 5 % & 11.8 % in younger than 6 months.

Pneumonia complicating measles: 27 %-77 % bacterial superinfection.

Influenza vacccines prevent 87% of influenza assoc. pneumonia –pneumococcal & MRSA superinfection.

13 valent Pnemococcal vaccine (PCV13)-additional serotypes assoc. with empyema & necrotizing pneumonia.

High risk infants-RSV specific monoclonal antibody decrease risk of pneumonia & hospitalization.

Diagnosis of CAP –not through microbiological isolation but from clinical symptoms & signs –supported by radiography & serum laboratory tests.

Causative pathogens challenging to isolate & age is the best predictor of cause.

Substantial propotion of CAP-mixed bacterial & viral pneumonia

IDSA guidelines in children >5 yrs or 5yrs or more –Amoxicillin 90 mg/kg/day orally in 2 divided doses –presumed bacterial pneumonia.

Azithromycin 10 mg/kg on day 1 & 5mg/kg on days 2-5-presumed Atypical pneumonia.

Macrolide can be added to beta lactumantibiotic –difficult to distinguish b/w bacterial & atypical CAP.

CAP is changing both in cause & management

More molecular diagnostic techniques are under trial.

1. Two bacteria predom. responsible for fatal pneumonia in children ?

2.Defn. of CAP according to WHO, BTS, IDSA ?

3.Microbial agents causing CAP in birth-20 days ?

4.Common differential diagnosis for round pneumonia ?

5.Treatment for CAP according to IDSA guidelines with dosage ?

6.DFA testing used for which micro organism